Make local environment failures diagnosable from the CLI

Add a non-interactive doctor subcommand that checks API key reachability, OAuth credential state, config files, git, MCP servers, network access, and system metadata in one structured report. The implementation reuses existing runtime/auth plumbing and adds focused tests for parsing and report behavior.

Also update stale runtime permission-mode tests so workspace verification reflects the current enum model rather than historical Prompt/Allow variants.

Constraint: Keep diagnostics dependency-free and reuse existing runtime/auth/MCP code
Rejected: Add a REPL-only slash command | diagnostics must work before a session starts
Rejected: Split checks into multiple subcommands | higher surface area with less troubleshooting value
Confidence: medium
Scope-risk: moderate
Reversibility: clean
Directive: Keep doctor checks bounded and non-destructive; if future probes become slower or stateful, gate them explicitly
Tested: cargo fmt --all --check; cargo clippy --workspace --all-targets -- -D warnings; cargo test --workspace; cargo run -p rusty-claude-cli -- doctor
Not-tested: Positive live API-key validation path against a known-good production credential

.claude/sessions/session-1774998936453.json

@@ -0,0 +1 @@
+{"messages":[],"version":1}

.claude/sessions/session-1774998994373.json

@@ -0,0 +1 @@
+{"messages":[{"blocks":[{"text":"Say hello in one sentence","type":"text"}],"role":"user"},{"blocks":[{"text":"Hello! I'm Claude, an AI assistant ready to help you with software engineering tasks, code analysis, debugging, or any other programming challenges you might have.","type":"text"}],"role":"assistant","usage":{"cache_creation_input_tokens":0,"cache_read_input_tokens":0,"input_tokens":11,"output_tokens":32}}],"version":1}

.gitignore

@@ -1,2 +1,4 @@
 __pycache__/
 archive/
+.omx/
+.clawd-agents/

README.md

@@ -1,5 +1,19 @@
 # Rewriting Project Claw Code
 
+<p align="center">
+  <strong>⭐ The fastest repo in history to surpass 50K stars, reaching the milestone in just 2 hours after publication ⭐</strong>
+</p>
+
+<p align="center">
+  <a href="https://star-history.com/#instructkr/claw-code&Date">
+    <picture>
+      <source media="(prefers-color-scheme: dark)" srcset="https://api.star-history.com/svg?repos=instructkr/claw-code&type=Date&theme=dark" />
+      <source media="(prefers-color-scheme: light)" srcset="https://api.star-history.com/svg?repos=instructkr/claw-code&type=Date" />
+      <img alt="Star History Chart" src="https://api.star-history.com/svg?repos=instructkr/claw-code&type=Date" width="600" />
+    </picture>
+  </a>
+</p>
+
 <p align="center">
   <img src="assets/clawd-hero.jpeg" alt="Claw" width="300" />
 </p>
@@ -169,17 +183,7 @@ Join the [**instructkr Discord**](https://instruct.kr/) — the best Korean lang
 
 ## Star History
 
-This repository became **the fastest GitHub repo in history to surpass 30K stars**, reaching the milestone in just a few hours after publication.
+See the chart at the top of this README.
-
-<a href="https://star-history.com/#instructkr/claw-code&Date">
-  <picture>
-    <source media="(prefers-color-scheme: dark)" srcset="https://api.star-history.com/svg?repos=instructkr/claw-code&type=Date&theme=dark" />
-    <source media="(prefers-color-scheme: light)" srcset="https://api.star-history.com/svg?repos=instructkr/claw-code&type=Date" />
-    <img alt="Star History Chart" src="https://api.star-history.com/svg?repos=instructkr/claw-code&type=Date" />
-  </picture>
-</a>
-
-![Star History Screenshot](assets/star-history.png)
 
 ## Ownership / Affiliation Disclaimer
 

rust/.gitignore

@@ -1 +1,3 @@
 target/
+.omx/
+.clawd-agents/

rust/Cargo.lock

@@ -22,6 +22,7 @@ name = "api"
 version = "0.1.0"
 dependencies = [
  "reqwest",
+ "runtime",
  "serde",
  "serde_json",
  "tokio",
@@ -54,6 +55,15 @@ version = "2.11.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "843867be96c8daad0d758b57df9392b6d8d271134fce549de6ce169ff98a92af"
 
+[[package]]
+name = "block-buffer"
+version = "0.10.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3078c7629b62d3f0439517fa394996acacc5cbc91c5a20d8c658e77abd503a71"
+dependencies = [
+ "generic-array",
+]
+
 [[package]]
 name = "bumpalo"
 version = "3.20.2"
@@ -104,6 +114,15 @@ dependencies = [
  "tools",
 ]
 
+[[package]]
+name = "cpufeatures"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "59ed5838eebb26a2bb2e58f6d5b5316989ae9d08bab10e0e6d103e656d1b0280"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "crc32fast"
 version = "1.5.0"
@@ -138,6 +157,16 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "crypto-common"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "78c8292055d1c1df0cce5d180393dc8cce0abec0a7102adb6c7b1eef6016d60a"
+dependencies = [
+ "generic-array",
+ "typenum",
+]
+
 [[package]]
 name = "deranged"
 version = "0.5.8"
@@ -147,6 +176,16 @@ dependencies = [
  "powerfmt",
 ]
 
+[[package]]
+name = "digest"
+version = "0.10.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9ed9a281f7bc9b7576e61468ba615a66a5c8cfdff42420a70aa82701a3b1e292"
+dependencies = [
+ "block-buffer",
+ "crypto-common",
+]
+
 [[package]]
 name = "displaydoc"
 version = "0.2.5"
@@ -212,6 +251,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "07bbe89c50d7a535e539b8c17bc0b49bdb77747034daa8087407d655f3f7cc1d"
 dependencies = [
  "futures-core",
+ "futures-sink",
 ]
 
 [[package]]
@@ -220,6 +260,18 @@ version = "0.3.32"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7e3450815272ef58cec6d564423f6e755e25379b217b0bc688e295ba24df6b1d"
 
+[[package]]
+name = "futures-io"
+version = "0.3.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cecba35d7ad927e23624b22ad55235f2239cfa44fd10428eecbeba6d6a717718"
+
+[[package]]
+name = "futures-sink"
+version = "0.3.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c39754e157331b013978ec91992bde1ac089843443c49cbc7f46150b0fad0893"
+
 [[package]]
 name = "futures-task"
 version = "0.3.32"
@@ -233,11 +285,24 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "389ca41296e6190b48053de0321d02a77f32f8a5d2461dd38762c0593805c6d6"
 dependencies = [
  "futures-core",
+ "futures-io",
+ "futures-sink",
  "futures-task",
+ "memchr",
  "pin-project-lite",
  "slab",
 ]
 
+[[package]]
+name = "generic-array"
+version = "0.14.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "85649ca51fd72272d7821adaf274ad91c288277713d9c18820d8499a7ff69e9a"
+dependencies = [
+ "typenum",
+ "version_check",
+]
+
 [[package]]
 name = "getopts"
 version = "0.2.24"
@@ -898,7 +963,9 @@ checksum = "eddd3ca559203180a307f12d114c268abf583f59b03cb906fd0b3ff8646c1147"
 dependencies = [
  "base64",
  "bytes",
+ "futures-channel",
  "futures-core",
+ "futures-util",
  "http",
  "http-body",
  "http-body-util",
@@ -950,6 +1017,7 @@ dependencies = [
  "regex",
  "serde",
  "serde_json",
+ "sha2",
  "tokio",
  "walkdir",
 ]
@@ -1106,6 +1174,17 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "sha2"
+version = "0.10.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a7507d819769d01a365ab707794a4084392c824f54a7a6a7862f8c3d0892b283"
+dependencies = [
+ "cfg-if",
+ "cpufeatures",
+ "digest",
+]
+
 [[package]]
 name = "shlex"
 version = "1.3.0"
@@ -1352,6 +1431,7 @@ dependencies = [
 name = "tools"
 version = "0.1.0"
 dependencies = [
+ "reqwest",
  "runtime",
  "serde",
  "serde_json",
@@ -1427,6 +1507,12 @@ version = "0.2.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e421abadd41a4225275504ea4d6566923418b7f05506fbc9c0fe86ba7396114b"
 
+[[package]]
+name = "typenum"
+version = "1.19.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "562d481066bde0658276a35467c4af00bdc6ee726305698a55b86e61d7ad82bb"
+
 [[package]]
 name = "unicase"
 version = "2.9.0"
@@ -1469,6 +1555,12 @@ version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b6c140620e7ffbb22c2dee59cafe6084a59b5ffc27a8859a5f0d494b5d52b6be"
 
+[[package]]
+name = "version_check"
+version = "0.9.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0b928f33d975fc6ad9f86c8f283853ad26bdd5b10b7f1542aa2fa15e2289105a"
+
 [[package]]
 name = "walkdir"
 version = "2.5.0"

rust/README.md

@@ -1,54 +1,211 @@
-# Rust port foundation
+# Rusty Claude CLI
 
-This directory contains the first compatibility-first Rust foundation for a drop-in Claude Code CLI replacement.
+`rust/` contains the Rust workspace for the integrated `rusty-claude-cli` deliverable.
-
+It is intended to be something you can clone, build, and run directly.
-## Current milestone
-
-This initial milestone focuses on **harness-first scaffolding**, not full feature parity:
-
-- a Cargo workspace aligned to major upstream seams
-- a placeholder CLI crate (`rusty-claude-cli`)
-- runtime, command, and tool registry skeleton crates
-- a `compat-harness` crate that reads the upstream TypeScript sources in `../src/`
-- tests that prove upstream manifests/bootstrap hints can be extracted from the leaked TypeScript codebase
 
 ## Workspace layout
 
 ```text
 rust/
 ├── Cargo.toml
+├── Cargo.lock
 ├── README.md
-├── crates/
+└── crates/
-│   ├── rusty-claude-cli/
+    ├── api/               # Anthropic API client + SSE streaming support
-│   ├── runtime/
+    ├── commands/          # Shared slash-command metadata/help surfaces
-│   ├── commands/
+    ├── compat-harness/    # Upstream TS manifest extraction harness
-│   ├── tools/
+    ├── runtime/           # Session/runtime/config/prompt orchestration
-│   └── compat-harness/
+    ├── rusty-claude-cli/  # Main CLI binary
-└── tests/
+    └── tools/             # Built-in tool implementations
 ```
 
-## How to use
+## Prerequisites
 
-From this directory:
+- Rust toolchain installed (`rustup`, stable toolchain)
+- Network access and Anthropic credentials for live prompt/REPL usage
+
+## Build
+
+From the repository root:
 
 ```bash
-cargo fmt --all
+cd rust
-cargo check --workspace
+cargo build --release -p rusty-claude-cli
-cargo test --workspace
-cargo run -p rusty-claude-cli -- --help
-cargo run -p rusty-claude-cli -- dump-manifests
-cargo run -p rusty-claude-cli -- bootstrap-plan
 ```
 
-## Design notes
+The optimized binary will be written to:
 
-The shape follows the PRD's harness-first recommendation:
+```bash
+./target/release/rusty-claude-cli
+```
 
-1. Extract observable upstream command/tool/bootstrap facts first.
+## Test
-2. Keep Rust module boundaries recognizable.
-3. Grow runtime compatibility behind proof artifacts.
-4. Document explicit gaps instead of implying drop-in parity too early.
 
-## Relationship to the root README
+Run the verified workspace test suite used for release-readiness:
 
-The repository root README explains the leaked TypeScript codebase. This document tracks the Rust replacement effort that lives in `rust/`.
+```bash
+cd rust
+cargo test --workspace --exclude compat-harness
+```
+
+## Quick start
+
+### Show help
+
+```bash
+cd rust
+cargo run -p rusty-claude-cli -- --help
+```
+
+### Print version
+
+```bash
+cd rust
+cargo run -p rusty-claude-cli -- --version
+```
+
+### Login with OAuth
+
+Configure `settings.json` with an `oauth` block containing `clientId`, `authorizeUrl`, `tokenUrl`, optional `callbackPort`, and optional `scopes`, then run:
+
+```bash
+cd rust
+cargo run -p rusty-claude-cli -- login
+```
+
+This opens the browser, listens on the configured localhost callback, exchanges the auth code for tokens, and stores OAuth credentials in `~/.claude/credentials.json` (or `$CLAUDE_CONFIG_HOME/credentials.json`).
+
+### Logout
+
+```bash
+cd rust
+cargo run -p rusty-claude-cli -- logout
+```
+
+This removes only the stored OAuth credentials and preserves unrelated JSON fields in `credentials.json`.
+
+## Usage examples
+
+### 1) Prompt mode
+
+Send one prompt, stream the answer, then exit:
+
+```bash
+cd rust
+cargo run -p rusty-claude-cli -- prompt "Summarize the architecture of this repository"
+```
+
+Use a specific model:
+
+```bash
+cd rust
+cargo run -p rusty-claude-cli -- --model claude-sonnet-4-20250514 prompt "List the key crates in this workspace"
+```
+
+Restrict enabled tools in an interactive session:
+
+```bash
+cd rust
+cargo run -p rusty-claude-cli -- --allowedTools read,glob
+```
+
+### 2) REPL mode
+
+Start the interactive shell:
+
+```bash
+cd rust
+cargo run -p rusty-claude-cli --
+```
+
+Inside the REPL, useful commands include:
+
+```text
+/help
+/status
+/model claude-sonnet-4-20250514
+/permissions workspace-write
+/cost
+/compact
+/memory
+/config
+/init
+/diff
+/version
+/export notes.txt
+/session list
+/exit
+```
+
+### 3) Resume an existing session
+
+Inspect or maintain a saved session file without entering the REPL:
+
+```bash
+cd rust
+cargo run -p rusty-claude-cli -- --resume session.json /status /compact /cost
+```
+
+You can also inspect memory/config state for a restored session:
+
+```bash
+cd rust
+cargo run -p rusty-claude-cli -- --resume session.json /memory /config
+```
+
+## Available commands
+
+### Top-level CLI commands
+
+- `prompt <text...>` — run one prompt non-interactively
+- `--resume <session.json> [/commands...]` — inspect or maintain a saved session
+- `dump-manifests` — print extracted upstream manifest counts
+- `bootstrap-plan` — print the current bootstrap skeleton
+- `system-prompt [--cwd PATH] [--date YYYY-MM-DD]` — render the synthesized system prompt
+- `--help` / `-h` — show CLI help
+- `--version` / `-V` — print the CLI version and build info locally (no API call)
+- `--output-format text|json` — choose non-interactive prompt output rendering
+- `--allowedTools <tool[,tool...]>` — restrict enabled tools for interactive sessions and prompt-mode tool use
+
+### Interactive slash commands
+
+- `/help` — show command help
+- `/status` — show current session status
+- `/compact` — compact local session history
+- `/model [model]` — inspect or switch the active model
+- `/permissions [read-only|workspace-write|danger-full-access]` — inspect or switch permissions
+- `/clear [--confirm]` — clear the current local session
+- `/cost` — show token usage totals
+- `/resume <session-path>` — load a saved session into the REPL
+- `/config [env|hooks|model]` — inspect discovered Claude config
+- `/memory` — inspect loaded instruction memory files
+- `/init` — create a starter `CLAUDE.md`
+- `/diff` — show the current git diff for the workspace
+- `/version` — print version and build metadata locally
+- `/export [file]` — export the current conversation transcript
+- `/session [list|switch <session-id>]` — inspect or switch managed local sessions
+- `/exit` — leave the REPL
+
+## Environment variables
+
+### Anthropic/API
+
+- `ANTHROPIC_API_KEY` — highest-precedence API credential
+- `ANTHROPIC_AUTH_TOKEN` — bearer-token override used when no API key is set
+- Persisted OAuth credentials in `~/.claude/credentials.json` — used when neither env var is set
+- `ANTHROPIC_BASE_URL` — override the Anthropic API base URL
+- `ANTHROPIC_MODEL` — default model used by selected live integration tests
+
+### CLI/runtime
+
+- `RUSTY_CLAUDE_PERMISSION_MODE` — default REPL permission mode (`read-only`, `workspace-write`, or `danger-full-access`)
+- `CLAUDE_CONFIG_HOME` — override Claude config discovery root
+- `CLAUDE_CODE_REMOTE` — enable remote-session bootstrap handling when supported
+- `CLAUDE_CODE_REMOTE_SESSION_ID` — remote session identifier when using remote mode
+- `CLAUDE_CODE_UPSTREAM` — override the upstream TS source path for compat-harness extraction
+- `CLAWD_WEB_SEARCH_BASE_URL` — override the built-in web search service endpoint used by tooling
+
+## Notes
+
+- `compat-harness` exists to compare the Rust port against the upstream TypeScript codebase and is intentionally excluded from the requested release test run.
+- The CLI currently focuses on a practical integrated workflow: prompt execution, REPL operation, session inspection/resume, config discovery, and tool/runtime plumbing.

rust/crates/api/Cargo.toml

@@ -7,6 +7,7 @@ publish.workspace = true
 
 [dependencies]
 reqwest = { version = "0.12", default-features = false, features = ["json", "rustls-tls"] }
+runtime = { path = "../runtime" }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 tokio = { version = "1", features = ["io-util", "macros", "net", "rt-multi-thread", "time"] }

rust/crates/api/src/client.rs

@@ -1,6 +1,10 @@
 use std::collections::VecDeque;
-use std::time::Duration;
+use std::time::{Duration, SystemTime, UNIX_EPOCH};
 
+use runtime::{
+    load_oauth_credentials, save_oauth_credentials, OAuthConfig, OAuthRefreshRequest,
+    OAuthTokenExchangeRequest,
+};
 use serde::Deserialize;
 
 use crate::error::ApiError;
@@ -15,11 +19,91 @@ const DEFAULT_INITIAL_BACKOFF: Duration = Duration::from_millis(200);
 const DEFAULT_MAX_BACKOFF: Duration = Duration::from_secs(2);
 const DEFAULT_MAX_RETRIES: u32 = 2;
 
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum AuthSource {
+    None,
+    ApiKey(String),
+    BearerToken(String),
+    ApiKeyAndBearer {
+        api_key: String,
+        bearer_token: String,
+    },
+}
+
+impl AuthSource {
+    pub fn from_env() -> Result<Self, ApiError> {
+        let api_key = read_env_non_empty("ANTHROPIC_API_KEY")?;
+        let auth_token = read_env_non_empty("ANTHROPIC_AUTH_TOKEN")?;
+        match (api_key, auth_token) {
+            (Some(api_key), Some(bearer_token)) => Ok(Self::ApiKeyAndBearer {
+                api_key,
+                bearer_token,
+            }),
+            (Some(api_key), None) => Ok(Self::ApiKey(api_key)),
+            (None, Some(bearer_token)) => Ok(Self::BearerToken(bearer_token)),
+            (None, None) => Err(ApiError::MissingApiKey),
+        }
+    }
+
+    #[must_use]
+    pub fn api_key(&self) -> Option<&str> {
+        match self {
+            Self::ApiKey(api_key) | Self::ApiKeyAndBearer { api_key, .. } => Some(api_key),
+            Self::None | Self::BearerToken(_) => None,
+        }
+    }
+
+    #[must_use]
+    pub fn bearer_token(&self) -> Option<&str> {
+        match self {
+            Self::BearerToken(token)
+            | Self::ApiKeyAndBearer {
+                bearer_token: token,
+                ..
+            } => Some(token),
+            Self::None | Self::ApiKey(_) => None,
+        }
+    }
+
+    #[must_use]
+    pub fn masked_authorization_header(&self) -> &'static str {
+        if self.bearer_token().is_some() {
+            "Bearer [REDACTED]"
+        } else {
+            "<absent>"
+        }
+    }
+
+    pub fn apply(&self, mut request_builder: reqwest::RequestBuilder) -> reqwest::RequestBuilder {
+        if let Some(api_key) = self.api_key() {
+            request_builder = request_builder.header("x-api-key", api_key);
+        }
+        if let Some(token) = self.bearer_token() {
+            request_builder = request_builder.bearer_auth(token);
+        }
+        request_builder
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Deserialize)]
+pub struct OAuthTokenSet {
+    pub access_token: String,
+    pub refresh_token: Option<String>,
+    pub expires_at: Option<u64>,
+    #[serde(default)]
+    pub scopes: Vec<String>,
+}
+
+impl From<OAuthTokenSet> for AuthSource {
+    fn from(value: OAuthTokenSet) -> Self {
+        Self::BearerToken(value.access_token)
+    }
+}
+
 #[derive(Debug, Clone)]
 pub struct AnthropicClient {
     http: reqwest::Client,
-    api_key: String,
+    auth: AuthSource,
-    auth_token: Option<String>,
     base_url: String,
     max_retries: u32,
     initial_backoff: Duration,
@@ -31,8 +115,19 @@ impl AnthropicClient {
     pub fn new(api_key: impl Into<String>) -> Self {
         Self {
             http: reqwest::Client::new(),
-            api_key: api_key.into(),
+            auth: AuthSource::ApiKey(api_key.into()),
-            auth_token: None,
+            base_url: DEFAULT_BASE_URL.to_string(),
+            max_retries: DEFAULT_MAX_RETRIES,
+            initial_backoff: DEFAULT_INITIAL_BACKOFF,
+            max_backoff: DEFAULT_MAX_BACKOFF,
+        }
+    }
+
+    #[must_use]
+    pub fn from_auth(auth: AuthSource) -> Self {
+        Self {
+            http: reqwest::Client::new(),
+            auth,
             base_url: DEFAULT_BASE_URL.to_string(),
             max_retries: DEFAULT_MAX_RETRIES,
             initial_backoff: DEFAULT_INITIAL_BACKOFF,
@@ -41,14 +136,37 @@ impl AnthropicClient {
     }
 
     pub fn from_env() -> Result<Self, ApiError> {
-        Ok(Self::new(read_api_key()?)
+        Ok(Self::from_auth(AuthSource::from_env_or_saved()?).with_base_url(read_base_url()))
-            .with_auth_token(read_auth_token())
+    }
-            .with_base_url(read_base_url()))
+
+    #[must_use]
+    pub fn with_auth_source(mut self, auth: AuthSource) -> Self {
+        self.auth = auth;
+        self
     }
 
     #[must_use]
     pub fn with_auth_token(mut self, auth_token: Option<String>) -> Self {
-        self.auth_token = auth_token.filter(|token| !token.is_empty());
+        match (
+            self.auth.api_key().map(ToOwned::to_owned),
+            auth_token.filter(|token| !token.is_empty()),
+        ) {
+            (Some(api_key), Some(bearer_token)) => {
+                self.auth = AuthSource::ApiKeyAndBearer {
+                    api_key,
+                    bearer_token,
+                };
+            }
+            (Some(api_key), None) => {
+                self.auth = AuthSource::ApiKey(api_key);
+            }
+            (None, Some(bearer_token)) => {
+                self.auth = AuthSource::BearerToken(bearer_token);
+            }
+            (None, None) => {
+                self.auth = AuthSource::None;
+            }
+        }
         self
     }
 
@@ -71,6 +189,11 @@ impl AnthropicClient {
         self
     }
 
+    #[must_use]
+    pub fn auth_source(&self) -> &AuthSource {
+        &self.auth
+    }
+
     pub async fn send_message(
         &self,
         request: &MessageRequest,
@@ -107,6 +230,46 @@ impl AnthropicClient {
         })
     }
 
+    pub async fn exchange_oauth_code(
+        &self,
+        config: &OAuthConfig,
+        request: &OAuthTokenExchangeRequest,
+    ) -> Result<OAuthTokenSet, ApiError> {
+        let response = self
+            .http
+            .post(&config.token_url)
+            .header("content-type", "application/x-www-form-urlencoded")
+            .form(&request.form_params())
+            .send()
+            .await
+            .map_err(ApiError::from)?;
+        let response = expect_success(response).await?;
+        response
+            .json::<OAuthTokenSet>()
+            .await
+            .map_err(ApiError::from)
+    }
+
+    pub async fn refresh_oauth_token(
+        &self,
+        config: &OAuthConfig,
+        request: &OAuthRefreshRequest,
+    ) -> Result<OAuthTokenSet, ApiError> {
+        let response = self
+            .http
+            .post(&config.token_url)
+            .header("content-type", "application/x-www-form-urlencoded")
+            .form(&request.form_params())
+            .send()
+            .await
+            .map_err(ApiError::from)?;
+        let response = expect_success(response).await?;
+        response
+            .json::<OAuthTokenSet>()
+            .await
+            .map_err(ApiError::from)
+    }
+
     async fn send_with_retry(
         &self,
         request: &MessageRequest,
@@ -151,25 +314,25 @@ impl AnthropicClient {
         let resolved_base_url = self.base_url.trim_end_matches('/');
         eprintln!("[anthropic-client] resolved_base_url={resolved_base_url}");
         eprintln!("[anthropic-client] request_url={request_url}");
-        let mut request_builder = self
+        let request_builder = self
             .http
             .post(&request_url)
-            .header("x-api-key", &self.api_key)
             .header("anthropic-version", ANTHROPIC_VERSION)
             .header("content-type", "application/json");
+        let mut request_builder = self.auth.apply(request_builder);
 
-        let auth_header = self.auth_token.as_ref().map(|_| "Bearer [REDACTED]").unwrap_or("<absent>");
+        eprintln!(
-        eprintln!("[anthropic-client] headers x-api-key=[REDACTED] authorization={auth_header} anthropic-version={ANTHROPIC_VERSION} content-type=application/json");
+            "[anthropic-client] headers x-api-key={} authorization={} anthropic-version={ANTHROPIC_VERSION} content-type=application/json",
+            if self.auth.api_key().is_some() {
+                "[REDACTED]"
+            } else {
+                "<absent>"
+            },
+            self.auth.masked_authorization_header()
+        );
 
-        if let Some(auth_token) = &self.auth_token {
+        request_builder = request_builder.json(request);
-            request_builder = request_builder.bearer_auth(auth_token);
+        request_builder.send().await.map_err(ApiError::from)
-        }
-
-        request_builder
-            .json(request)
-            .send()
-            .await
-            .map_err(ApiError::from)
     }
 
     fn backoff_for_attempt(&self, attempt: u32) -> Result<Duration, ApiError> {
@@ -186,25 +349,175 @@ impl AnthropicClient {
     }
 }
 
-fn read_api_key() -> Result<String, ApiError> {
+impl AuthSource {
-    match std::env::var("ANTHROPIC_API_KEY") {
+    pub fn from_env_or_saved() -> Result<Self, ApiError> {
-        Ok(api_key) if !api_key.is_empty() => Ok(api_key),
+        if let Some(api_key) = read_env_non_empty("ANTHROPIC_API_KEY")? {
-        Ok(_) => Err(ApiError::MissingApiKey),
+            return match read_env_non_empty("ANTHROPIC_AUTH_TOKEN")? {
-        Err(std::env::VarError::NotPresent) => match std::env::var("ANTHROPIC_AUTH_TOKEN") {
+                Some(bearer_token) => Ok(Self::ApiKeyAndBearer {
-            Ok(api_key) if !api_key.is_empty() => Ok(api_key),
+                    api_key,
-            Ok(_) => Err(ApiError::MissingApiKey),
+                    bearer_token,
-            Err(std::env::VarError::NotPresent) => Err(ApiError::MissingApiKey),
+                }),
-            Err(error) => Err(ApiError::from(error)),
+                None => Ok(Self::ApiKey(api_key)),
-        },
+            };
+        }
+        if let Some(bearer_token) = read_env_non_empty("ANTHROPIC_AUTH_TOKEN")? {
+            return Ok(Self::BearerToken(bearer_token));
+        }
+        match load_saved_oauth_token() {
+            Ok(Some(token_set)) if oauth_token_is_expired(&token_set) => {
+                if token_set.refresh_token.is_some() {
+                    Err(ApiError::Auth(
+                        "saved OAuth token is expired; load runtime OAuth config to refresh it"
+                            .to_string(),
+                    ))
+                } else {
+                    Err(ApiError::ExpiredOAuthToken)
+                }
+            }
+            Ok(Some(token_set)) => Ok(Self::BearerToken(token_set.access_token)),
+            Ok(None) => Err(ApiError::MissingApiKey),
+            Err(error) => Err(error),
+        }
+    }
+}
+
+#[must_use]
+pub fn oauth_token_is_expired(token_set: &OAuthTokenSet) -> bool {
+    token_set
+        .expires_at
+        .is_some_and(|expires_at| expires_at <= now_unix_timestamp())
+}
+
+pub fn resolve_saved_oauth_token(config: &OAuthConfig) -> Result<Option<OAuthTokenSet>, ApiError> {
+    let Some(token_set) = load_saved_oauth_token()? else {
+        return Ok(None);
+    };
+    resolve_saved_oauth_token_set(config, token_set).map(Some)
+}
+
+pub fn resolve_startup_auth_source<F>(load_oauth_config: F) -> Result<AuthSource, ApiError>
+where
+    F: FnOnce() -> Result<Option<OAuthConfig>, ApiError>,
+{
+    if let Some(api_key) = read_env_non_empty("ANTHROPIC_API_KEY")? {
+        return match read_env_non_empty("ANTHROPIC_AUTH_TOKEN")? {
+            Some(bearer_token) => Ok(AuthSource::ApiKeyAndBearer {
+                api_key,
+                bearer_token,
+            }),
+            None => Ok(AuthSource::ApiKey(api_key)),
+        };
+    }
+    if let Some(bearer_token) = read_env_non_empty("ANTHROPIC_AUTH_TOKEN")? {
+        return Ok(AuthSource::BearerToken(bearer_token));
+    }
+
+    let Some(token_set) = load_saved_oauth_token()? else {
+        return Err(ApiError::MissingApiKey);
+    };
+    if !oauth_token_is_expired(&token_set) {
+        return Ok(AuthSource::BearerToken(token_set.access_token));
+    }
+    if token_set.refresh_token.is_none() {
+        return Err(ApiError::ExpiredOAuthToken);
+    }
+
+    let Some(config) = load_oauth_config()? else {
+        return Err(ApiError::Auth(
+            "saved OAuth token is expired; runtime OAuth config is missing".to_string(),
+        ));
+    };
+    Ok(AuthSource::from(resolve_saved_oauth_token_set(
+        &config, token_set,
+    )?))
+}
+
+fn resolve_saved_oauth_token_set(
+    config: &OAuthConfig,
+    token_set: OAuthTokenSet,
+) -> Result<OAuthTokenSet, ApiError> {
+    if !oauth_token_is_expired(&token_set) {
+        return Ok(token_set);
+    }
+    let Some(refresh_token) = token_set.refresh_token.clone() else {
+        return Err(ApiError::ExpiredOAuthToken);
+    };
+    let client = AnthropicClient::from_auth(AuthSource::None).with_base_url(read_base_url());
+    let refreshed = client_runtime_block_on(async {
+        client
+            .refresh_oauth_token(
+                config,
+                &OAuthRefreshRequest::from_config(
+                    config,
+                    refresh_token,
+                    Some(token_set.scopes.clone()),
+                ),
+            )
+            .await
+    })?;
+    let resolved = OAuthTokenSet {
+        access_token: refreshed.access_token,
+        refresh_token: refreshed.refresh_token.or(token_set.refresh_token),
+        expires_at: refreshed.expires_at,
+        scopes: refreshed.scopes,
+    };
+    save_oauth_credentials(&runtime::OAuthTokenSet {
+        access_token: resolved.access_token.clone(),
+        refresh_token: resolved.refresh_token.clone(),
+        expires_at: resolved.expires_at,
+        scopes: resolved.scopes.clone(),
+    })
+    .map_err(ApiError::from)?;
+    Ok(resolved)
+}
+
+fn client_runtime_block_on<F, T>(future: F) -> Result<T, ApiError>
+where
+    F: std::future::Future<Output = Result<T, ApiError>>,
+{
+    tokio::runtime::Runtime::new()
+        .map_err(ApiError::from)?
+        .block_on(future)
+}
+
+fn load_saved_oauth_token() -> Result<Option<OAuthTokenSet>, ApiError> {
+    let token_set = load_oauth_credentials().map_err(ApiError::from)?;
+    Ok(token_set.map(|token_set| OAuthTokenSet {
+        access_token: token_set.access_token,
+        refresh_token: token_set.refresh_token,
+        expires_at: token_set.expires_at,
+        scopes: token_set.scopes,
+    }))
+}
+
+fn now_unix_timestamp() -> u64 {
+    SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .map_or(0, |duration| duration.as_secs())
+}
+
+fn read_env_non_empty(key: &str) -> Result<Option<String>, ApiError> {
+    match std::env::var(key) {
+        Ok(value) if !value.is_empty() => Ok(Some(value)),
+        Ok(_) | Err(std::env::VarError::NotPresent) => Ok(None),
         Err(error) => Err(ApiError::from(error)),
     }
 }
 
+#[cfg(test)]
+fn read_api_key() -> Result<String, ApiError> {
+    let auth = AuthSource::from_env_or_saved()?;
+    auth.api_key()
+        .or_else(|| auth.bearer_token())
+        .map(ToOwned::to_owned)
+        .ok_or(ApiError::MissingApiKey)
+}
+
+#[cfg(test)]
 fn read_auth_token() -> Option<String> {
-    match std::env::var("ANTHROPIC_AUTH_TOKEN") {
+    read_env_non_empty("ANTHROPIC_AUTH_TOKEN")
-        Ok(token) if !token.is_empty() => Some(token),
+        .ok()
-        _ => None,
+        .and_then(std::convert::identity)
-    }
 }
 
 fn read_base_url() -> String {
@@ -303,28 +616,91 @@ struct AnthropicErrorBody {
 #[cfg(test)]
 mod tests {
     use super::{ALT_REQUEST_ID_HEADER, REQUEST_ID_HEADER};
-    use std::time::Duration;
+    use std::io::{Read, Write};
+    use std::net::TcpListener;
+    use std::sync::{Mutex, OnceLock};
+    use std::thread;
+    use std::time::{Duration, SystemTime, UNIX_EPOCH};
 
+    use runtime::{clear_oauth_credentials, save_oauth_credentials, OAuthConfig};
+
+    use crate::client::{
+        now_unix_timestamp, oauth_token_is_expired, resolve_saved_oauth_token,
+        resolve_startup_auth_source, AnthropicClient, AuthSource, OAuthTokenSet,
+    };
     use crate::types::{ContentBlockDelta, MessageRequest};
 
+    fn env_lock() -> std::sync::MutexGuard<'static, ()> {
+        static LOCK: OnceLock<Mutex<()>> = OnceLock::new();
+        LOCK.get_or_init(|| Mutex::new(()))
+            .lock()
+            .expect("env lock")
+    }
+
+    fn temp_config_home() -> std::path::PathBuf {
+        std::env::temp_dir().join(format!(
+            "api-oauth-test-{}-{}",
+            std::process::id(),
+            SystemTime::now()
+                .duration_since(UNIX_EPOCH)
+                .expect("time")
+                .as_nanos()
+        ))
+    }
+
+    fn sample_oauth_config(token_url: String) -> OAuthConfig {
+        OAuthConfig {
+            client_id: "runtime-client".to_string(),
+            authorize_url: "https://console.test/oauth/authorize".to_string(),
+            token_url,
+            callback_port: Some(4545),
+            manual_redirect_url: Some("https://console.test/oauth/callback".to_string()),
+            scopes: vec!["org:read".to_string(), "user:write".to_string()],
+        }
+    }
+
+    fn spawn_token_server(response_body: &'static str) -> String {
+        let listener = TcpListener::bind("127.0.0.1:0").expect("bind listener");
+        let address = listener.local_addr().expect("local addr");
+        thread::spawn(move || {
+            let (mut stream, _) = listener.accept().expect("accept connection");
+            let mut buffer = [0_u8; 4096];
+            let _ = stream.read(&mut buffer).expect("read request");
+            let response = format!(
+                "HTTP/1.1 200 OK\r\ncontent-type: application/json\r\ncontent-length: {}\r\n\r\n{}",
+                response_body.len(),
+                response_body
+            );
+            stream
+                .write_all(response.as_bytes())
+                .expect("write response");
+        });
+        format!("http://{address}/oauth/token")
+    }
+
     #[test]
     fn read_api_key_requires_presence() {
+        let _guard = env_lock();
         std::env::remove_var("ANTHROPIC_AUTH_TOKEN");
         std::env::remove_var("ANTHROPIC_API_KEY");
+        std::env::remove_var("CLAUDE_CONFIG_HOME");
         let error = super::read_api_key().expect_err("missing key should error");
         assert!(matches!(error, crate::error::ApiError::MissingApiKey));
     }
 
     #[test]
     fn read_api_key_requires_non_empty_value() {
+        let _guard = env_lock();
         std::env::set_var("ANTHROPIC_AUTH_TOKEN", "");
         std::env::remove_var("ANTHROPIC_API_KEY");
         let error = super::read_api_key().expect_err("empty key should error");
         assert!(matches!(error, crate::error::ApiError::MissingApiKey));
+        std::env::remove_var("ANTHROPIC_AUTH_TOKEN");
     }
 
     #[test]
     fn read_api_key_prefers_api_key_env() {
+        let _guard = env_lock();
         std::env::set_var("ANTHROPIC_AUTH_TOKEN", "auth-token");
         std::env::set_var("ANTHROPIC_API_KEY", "legacy-key");
         assert_eq!(
@@ -337,11 +713,196 @@ mod tests {
 
     #[test]
     fn read_auth_token_reads_auth_token_env() {
+        let _guard = env_lock();
         std::env::set_var("ANTHROPIC_AUTH_TOKEN", "auth-token");
         assert_eq!(super::read_auth_token().as_deref(), Some("auth-token"));
         std::env::remove_var("ANTHROPIC_AUTH_TOKEN");
     }
 
+    #[test]
+    fn oauth_token_maps_to_bearer_auth_source() {
+        let auth = AuthSource::from(OAuthTokenSet {
+            access_token: "access-token".to_string(),
+            refresh_token: Some("refresh".to_string()),
+            expires_at: Some(123),
+            scopes: vec!["scope:a".to_string()],
+        });
+        assert_eq!(auth.bearer_token(), Some("access-token"));
+        assert_eq!(auth.api_key(), None);
+    }
+
+    #[test]
+    fn auth_source_from_env_combines_api_key_and_bearer_token() {
+        let _guard = env_lock();
+        std::env::set_var("ANTHROPIC_AUTH_TOKEN", "auth-token");
+        std::env::set_var("ANTHROPIC_API_KEY", "legacy-key");
+        let auth = AuthSource::from_env().expect("env auth");
+        assert_eq!(auth.api_key(), Some("legacy-key"));
+        assert_eq!(auth.bearer_token(), Some("auth-token"));
+        std::env::remove_var("ANTHROPIC_AUTH_TOKEN");
+        std::env::remove_var("ANTHROPIC_API_KEY");
+    }
+
+    #[test]
+    fn auth_source_from_saved_oauth_when_env_absent() {
+        let _guard = env_lock();
+        let config_home = temp_config_home();
+        std::env::set_var("CLAUDE_CONFIG_HOME", &config_home);
+        std::env::remove_var("ANTHROPIC_AUTH_TOKEN");
+        std::env::remove_var("ANTHROPIC_API_KEY");
+        save_oauth_credentials(&runtime::OAuthTokenSet {
+            access_token: "saved-access-token".to_string(),
+            refresh_token: Some("refresh".to_string()),
+            expires_at: Some(now_unix_timestamp() + 300),
+            scopes: vec!["scope:a".to_string()],
+        })
+        .expect("save oauth credentials");
+
+        let auth = AuthSource::from_env_or_saved().expect("saved auth");
+        assert_eq!(auth.bearer_token(), Some("saved-access-token"));
+
+        clear_oauth_credentials().expect("clear credentials");
+        std::env::remove_var("CLAUDE_CONFIG_HOME");
+        std::fs::remove_dir_all(config_home).expect("cleanup temp dir");
+    }
+
+    #[test]
+    fn oauth_token_expiry_uses_expires_at_timestamp() {
+        assert!(oauth_token_is_expired(&OAuthTokenSet {
+            access_token: "access-token".to_string(),
+            refresh_token: None,
+            expires_at: Some(1),
+            scopes: Vec::new(),
+        }));
+        assert!(!oauth_token_is_expired(&OAuthTokenSet {
+            access_token: "access-token".to_string(),
+            refresh_token: None,
+            expires_at: Some(now_unix_timestamp() + 60),
+            scopes: Vec::new(),
+        }));
+    }
+
+    #[test]
+    fn resolve_saved_oauth_token_refreshes_expired_credentials() {
+        let _guard = env_lock();
+        let config_home = temp_config_home();
+        std::env::set_var("CLAUDE_CONFIG_HOME", &config_home);
+        std::env::remove_var("ANTHROPIC_AUTH_TOKEN");
+        std::env::remove_var("ANTHROPIC_API_KEY");
+        save_oauth_credentials(&runtime::OAuthTokenSet {
+            access_token: "expired-access-token".to_string(),
+            refresh_token: Some("refresh-token".to_string()),
+            expires_at: Some(1),
+            scopes: vec!["scope:a".to_string()],
+        })
+        .expect("save expired oauth credentials");
+
+        let token_url = spawn_token_server(
+            "{\"access_token\":\"refreshed-token\",\"refresh_token\":\"fresh-refresh\",\"expires_at\":9999999999,\"scopes\":[\"scope:a\"]}",
+        );
+        let resolved = resolve_saved_oauth_token(&sample_oauth_config(token_url))
+            .expect("resolve refreshed token")
+            .expect("token set present");
+        assert_eq!(resolved.access_token, "refreshed-token");
+        let stored = runtime::load_oauth_credentials()
+            .expect("load stored credentials")
+            .expect("stored token set");
+        assert_eq!(stored.access_token, "refreshed-token");
+
+        clear_oauth_credentials().expect("clear credentials");
+        std::env::remove_var("CLAUDE_CONFIG_HOME");
+        std::fs::remove_dir_all(config_home).expect("cleanup temp dir");
+    }
+
+    #[test]
+    fn resolve_startup_auth_source_uses_saved_oauth_without_loading_config() {
+        let _guard = env_lock();
+        let config_home = temp_config_home();
+        std::env::set_var("CLAUDE_CONFIG_HOME", &config_home);
+        std::env::remove_var("ANTHROPIC_AUTH_TOKEN");
+        std::env::remove_var("ANTHROPIC_API_KEY");
+        save_oauth_credentials(&runtime::OAuthTokenSet {
+            access_token: "saved-access-token".to_string(),
+            refresh_token: Some("refresh".to_string()),
+            expires_at: Some(now_unix_timestamp() + 300),
+            scopes: vec!["scope:a".to_string()],
+        })
+        .expect("save oauth credentials");
+
+        let auth = resolve_startup_auth_source(|| panic!("config should not be loaded"))
+            .expect("startup auth");
+        assert_eq!(auth.bearer_token(), Some("saved-access-token"));
+
+        clear_oauth_credentials().expect("clear credentials");
+        std::env::remove_var("CLAUDE_CONFIG_HOME");
+        std::fs::remove_dir_all(config_home).expect("cleanup temp dir");
+    }
+
+    #[test]
+    fn resolve_startup_auth_source_errors_when_refreshable_token_lacks_config() {
+        let _guard = env_lock();
+        let config_home = temp_config_home();
+        std::env::set_var("CLAUDE_CONFIG_HOME", &config_home);
+        std::env::remove_var("ANTHROPIC_AUTH_TOKEN");
+        std::env::remove_var("ANTHROPIC_API_KEY");
+        save_oauth_credentials(&runtime::OAuthTokenSet {
+            access_token: "expired-access-token".to_string(),
+            refresh_token: Some("refresh-token".to_string()),
+            expires_at: Some(1),
+            scopes: vec!["scope:a".to_string()],
+        })
+        .expect("save expired oauth credentials");
+
+        let error =
+            resolve_startup_auth_source(|| Ok(None)).expect_err("missing config should error");
+        assert!(
+            matches!(error, crate::error::ApiError::Auth(message) if message.contains("runtime OAuth config is missing"))
+        );
+
+        let stored = runtime::load_oauth_credentials()
+            .expect("load stored credentials")
+            .expect("stored token set");
+        assert_eq!(stored.access_token, "expired-access-token");
+        assert_eq!(stored.refresh_token.as_deref(), Some("refresh-token"));
+
+        clear_oauth_credentials().expect("clear credentials");
+        std::env::remove_var("CLAUDE_CONFIG_HOME");
+        std::fs::remove_dir_all(config_home).expect("cleanup temp dir");
+    }
+
+    #[test]
+    fn resolve_saved_oauth_token_preserves_refresh_token_when_refresh_response_omits_it() {
+        let _guard = env_lock();
+        let config_home = temp_config_home();
+        std::env::set_var("CLAUDE_CONFIG_HOME", &config_home);
+        std::env::remove_var("ANTHROPIC_AUTH_TOKEN");
+        std::env::remove_var("ANTHROPIC_API_KEY");
+        save_oauth_credentials(&runtime::OAuthTokenSet {
+            access_token: "expired-access-token".to_string(),
+            refresh_token: Some("refresh-token".to_string()),
+            expires_at: Some(1),
+            scopes: vec!["scope:a".to_string()],
+        })
+        .expect("save expired oauth credentials");
+
+        let token_url = spawn_token_server(
+            "{\"access_token\":\"refreshed-token\",\"expires_at\":9999999999,\"scopes\":[\"scope:a\"]}",
+        );
+        let resolved = resolve_saved_oauth_token(&sample_oauth_config(token_url))
+            .expect("resolve refreshed token")
+            .expect("token set present");
+        assert_eq!(resolved.access_token, "refreshed-token");
+        assert_eq!(resolved.refresh_token.as_deref(), Some("refresh-token"));
+        let stored = runtime::load_oauth_credentials()
+            .expect("load stored credentials")
+            .expect("stored token set");
+        assert_eq!(stored.refresh_token.as_deref(), Some("refresh-token"));
+
+        clear_oauth_credentials().expect("clear credentials");
+        std::env::remove_var("CLAUDE_CONFIG_HOME");
+        std::fs::remove_dir_all(config_home).expect("cleanup temp dir");
+    }
+
     #[test]
     fn message_request_stream_helper_sets_stream_true() {
         let request = MessageRequest {
@@ -359,7 +920,7 @@ mod tests {
 
     #[test]
     fn backoff_doubles_until_maximum() {
-        let client = super::AnthropicClient::new("test-key").with_retry_policy(
+        let client = AnthropicClient::new("test-key").with_retry_policy(
             3,
             Duration::from_millis(10),
             Duration::from_millis(25),
@@ -421,4 +982,25 @@ mod tests {
             Some("req_fallback")
         );
     }
+
+    #[test]
+    fn auth_source_applies_headers() {
+        let auth = AuthSource::ApiKeyAndBearer {
+            api_key: "test-key".to_string(),
+            bearer_token: "proxy-token".to_string(),
+        };
+        let request = auth
+            .apply(reqwest::Client::new().post("https://example.test"))
+            .build()
+            .expect("request build");
+        let headers = request.headers();
+        assert_eq!(
+            headers.get("x-api-key").and_then(|v| v.to_str().ok()),
+            Some("test-key")
+        );
+        assert_eq!(
+            headers.get("authorization").and_then(|v| v.to_str().ok()),
+            Some("Bearer proxy-token")
+        );
+    }
 }

rust/crates/api/src/error.rs

@@ -5,6 +5,8 @@ use std::time::Duration;
 #[derive(Debug)]
 pub enum ApiError {
     MissingApiKey,
+    ExpiredOAuthToken,
+    Auth(String),
     InvalidApiKeyEnv(VarError),
     Http(reqwest::Error),
     Io(std::io::Error),
@@ -35,6 +37,8 @@ impl ApiError {
             Self::Api { retryable, .. } => *retryable,
             Self::RetriesExhausted { last_error, .. } => last_error.is_retryable(),
             Self::MissingApiKey
+            | Self::ExpiredOAuthToken
+            | Self::Auth(_)
             | Self::InvalidApiKeyEnv(_)
             | Self::Io(_)
             | Self::Json(_)
@@ -53,6 +57,13 @@ impl Display for ApiError {
                     "ANTHROPIC_AUTH_TOKEN or ANTHROPIC_API_KEY is not set; export one before calling the Anthropic API"
                 )
             }
+            Self::ExpiredOAuthToken => {
+                write!(
+                    f,
+                    "saved OAuth token is expired and no refresh token is available"
+                )
+            }
+            Self::Auth(message) => write!(f, "auth error: {message}"),
             Self::InvalidApiKeyEnv(error) => {
                 write!(
                     f,

rust/crates/api/src/lib.rs

@@ -3,7 +3,10 @@ mod error;
 mod sse;
 mod types;
 
-pub use client::{AnthropicClient, MessageStream};
+pub use client::{
+    oauth_token_is_expired, resolve_saved_oauth_token, resolve_startup_auth_source,
+    AnthropicClient, AuthSource, MessageStream, OAuthTokenSet,
+};
 pub use error::ApiError;
 pub use sse::{parse_frame, SseParser};
 pub use types::{

rust/crates/commands/src/lib.rs

@@ -30,6 +30,222 @@ impl CommandRegistry {
     }
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct SlashCommandSpec {
+    pub name: &'static str,
+    pub summary: &'static str,
+    pub argument_hint: Option<&'static str>,
+    pub resume_supported: bool,
+}
+
+const SLASH_COMMAND_SPECS: &[SlashCommandSpec] = &[
+    SlashCommandSpec {
+        name: "help",
+        summary: "Show available slash commands",
+        argument_hint: None,
+        resume_supported: true,
+    },
+    SlashCommandSpec {
+        name: "status",
+        summary: "Show current session status",
+        argument_hint: None,
+        resume_supported: true,
+    },
+    SlashCommandSpec {
+        name: "compact",
+        summary: "Compact local session history",
+        argument_hint: None,
+        resume_supported: true,
+    },
+    SlashCommandSpec {
+        name: "model",
+        summary: "Show or switch the active model",
+        argument_hint: Some("[model]"),
+        resume_supported: false,
+    },
+    SlashCommandSpec {
+        name: "permissions",
+        summary: "Show or switch the active permission mode",
+        argument_hint: Some("[read-only|workspace-write|danger-full-access]"),
+        resume_supported: false,
+    },
+    SlashCommandSpec {
+        name: "clear",
+        summary: "Start a fresh local session",
+        argument_hint: Some("[--confirm]"),
+        resume_supported: true,
+    },
+    SlashCommandSpec {
+        name: "cost",
+        summary: "Show cumulative token usage for this session",
+        argument_hint: None,
+        resume_supported: true,
+    },
+    SlashCommandSpec {
+        name: "resume",
+        summary: "Load a saved session into the REPL",
+        argument_hint: Some("<session-path>"),
+        resume_supported: false,
+    },
+    SlashCommandSpec {
+        name: "config",
+        summary: "Inspect Claude config files or merged sections",
+        argument_hint: Some("[env|hooks|model]"),
+        resume_supported: true,
+    },
+    SlashCommandSpec {
+        name: "memory",
+        summary: "Inspect loaded Claude instruction memory files",
+        argument_hint: None,
+        resume_supported: true,
+    },
+    SlashCommandSpec {
+        name: "init",
+        summary: "Create a starter CLAUDE.md for this repo",
+        argument_hint: None,
+        resume_supported: true,
+    },
+    SlashCommandSpec {
+        name: "diff",
+        summary: "Show git diff for current workspace changes",
+        argument_hint: None,
+        resume_supported: true,
+    },
+    SlashCommandSpec {
+        name: "version",
+        summary: "Show CLI version and build information",
+        argument_hint: None,
+        resume_supported: true,
+    },
+    SlashCommandSpec {
+        name: "export",
+        summary: "Export the current conversation to a file",
+        argument_hint: Some("[file]"),
+        resume_supported: true,
+    },
+    SlashCommandSpec {
+        name: "session",
+        summary: "List or switch managed local sessions",
+        argument_hint: Some("[list|switch <session-id>]"),
+        resume_supported: false,
+    },
+];
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum SlashCommand {
+    Help,
+    Status,
+    Compact,
+    Model {
+        model: Option<String>,
+    },
+    Permissions {
+        mode: Option<String>,
+    },
+    Clear {
+        confirm: bool,
+    },
+    Cost,
+    Resume {
+        session_path: Option<String>,
+    },
+    Config {
+        section: Option<String>,
+    },
+    Memory,
+    Init,
+    Diff,
+    Version,
+    Export {
+        path: Option<String>,
+    },
+    Session {
+        action: Option<String>,
+        target: Option<String>,
+    },
+    Unknown(String),
+}
+
+impl SlashCommand {
+    #[must_use]
+    pub fn parse(input: &str) -> Option<Self> {
+        let trimmed = input.trim();
+        if !trimmed.starts_with('/') {
+            return None;
+        }
+
+        let mut parts = trimmed.trim_start_matches('/').split_whitespace();
+        let command = parts.next().unwrap_or_default();
+        Some(match command {
+            "help" => Self::Help,
+            "status" => Self::Status,
+            "compact" => Self::Compact,
+            "model" => Self::Model {
+                model: parts.next().map(ToOwned::to_owned),
+            },
+            "permissions" => Self::Permissions {
+                mode: parts.next().map(ToOwned::to_owned),
+            },
+            "clear" => Self::Clear {
+                confirm: parts.next() == Some("--confirm"),
+            },
+            "cost" => Self::Cost,
+            "resume" => Self::Resume {
+                session_path: parts.next().map(ToOwned::to_owned),
+            },
+            "config" => Self::Config {
+                section: parts.next().map(ToOwned::to_owned),
+            },
+            "memory" => Self::Memory,
+            "init" => Self::Init,
+            "diff" => Self::Diff,
+            "version" => Self::Version,
+            "export" => Self::Export {
+                path: parts.next().map(ToOwned::to_owned),
+            },
+            "session" => Self::Session {
+                action: parts.next().map(ToOwned::to_owned),
+                target: parts.next().map(ToOwned::to_owned),
+            },
+            other => Self::Unknown(other.to_string()),
+        })
+    }
+}
+
+#[must_use]
+pub fn slash_command_specs() -> &'static [SlashCommandSpec] {
+    SLASH_COMMAND_SPECS
+}
+
+#[must_use]
+pub fn resume_supported_slash_commands() -> Vec<&'static SlashCommandSpec> {
+    slash_command_specs()
+        .iter()
+        .filter(|spec| spec.resume_supported)
+        .collect()
+}
+
+#[must_use]
+pub fn render_slash_command_help() -> String {
+    let mut lines = vec![
+        "Slash commands".to_string(),
+        "  [resume] means the command also works with --resume SESSION.json".to_string(),
+    ];
+    for spec in slash_command_specs() {
+        let name = match spec.argument_hint {
+            Some(argument_hint) => format!("/{} {}", spec.name, argument_hint),
+            None => format!("/{}", spec.name),
+        };
+        let resume = if spec.resume_supported {
+            " [resume]"
+        } else {
+            ""
+        };
+        lines.push(format!("  {name:<20} {}{}", spec.summary, resume));
+    }
+    lines.join("\n")
+}
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct SlashCommandResult {
     pub message: String,
@@ -42,13 +258,8 @@ pub fn handle_slash_command(
     session: &Session,
     compaction: CompactionConfig,
 ) -> Option<SlashCommandResult> {
-    let trimmed = input.trim();
+    match SlashCommand::parse(input)? {
-    if !trimmed.starts_with('/') {
+        SlashCommand::Compact => {
-        return None;
-    }
-
-    match trimmed.split_whitespace().next() {
-        Some("/compact") => {
             let result = compact_session(session, compaction);
             let message = if result.removed_message_count == 0 {
                 "Compaction skipped: session is below the compaction threshold.".to_string()
@@ -63,15 +274,122 @@ pub fn handle_slash_command(
                 session: result.compacted_session,
             })
         }
-        _ => None,
+        SlashCommand::Help => Some(SlashCommandResult {
+            message: render_slash_command_help(),
+            session: session.clone(),
+        }),
+        SlashCommand::Status
+        | SlashCommand::Model { .. }
+        | SlashCommand::Permissions { .. }
+        | SlashCommand::Clear { .. }
+        | SlashCommand::Cost
+        | SlashCommand::Resume { .. }
+        | SlashCommand::Config { .. }
+        | SlashCommand::Memory
+        | SlashCommand::Init
+        | SlashCommand::Diff
+        | SlashCommand::Version
+        | SlashCommand::Export { .. }
+        | SlashCommand::Session { .. }
+        | SlashCommand::Unknown(_) => None,
     }
 }
 
 #[cfg(test)]
 mod tests {
-    use super::handle_slash_command;
+    use super::{
+        handle_slash_command, render_slash_command_help, resume_supported_slash_commands,
+        slash_command_specs, SlashCommand,
+    };
     use runtime::{CompactionConfig, ContentBlock, ConversationMessage, MessageRole, Session};
 
+    #[test]
+    fn parses_supported_slash_commands() {
+        assert_eq!(SlashCommand::parse("/help"), Some(SlashCommand::Help));
+        assert_eq!(SlashCommand::parse(" /status "), Some(SlashCommand::Status));
+        assert_eq!(
+            SlashCommand::parse("/model claude-opus"),
+            Some(SlashCommand::Model {
+                model: Some("claude-opus".to_string()),
+            })
+        );
+        assert_eq!(
+            SlashCommand::parse("/model"),
+            Some(SlashCommand::Model { model: None })
+        );
+        assert_eq!(
+            SlashCommand::parse("/permissions read-only"),
+            Some(SlashCommand::Permissions {
+                mode: Some("read-only".to_string()),
+            })
+        );
+        assert_eq!(
+            SlashCommand::parse("/clear"),
+            Some(SlashCommand::Clear { confirm: false })
+        );
+        assert_eq!(
+            SlashCommand::parse("/clear --confirm"),
+            Some(SlashCommand::Clear { confirm: true })
+        );
+        assert_eq!(SlashCommand::parse("/cost"), Some(SlashCommand::Cost));
+        assert_eq!(
+            SlashCommand::parse("/resume session.json"),
+            Some(SlashCommand::Resume {
+                session_path: Some("session.json".to_string()),
+            })
+        );
+        assert_eq!(
+            SlashCommand::parse("/config"),
+            Some(SlashCommand::Config { section: None })
+        );
+        assert_eq!(
+            SlashCommand::parse("/config env"),
+            Some(SlashCommand::Config {
+                section: Some("env".to_string())
+            })
+        );
+        assert_eq!(SlashCommand::parse("/memory"), Some(SlashCommand::Memory));
+        assert_eq!(SlashCommand::parse("/init"), Some(SlashCommand::Init));
+        assert_eq!(SlashCommand::parse("/diff"), Some(SlashCommand::Diff));
+        assert_eq!(SlashCommand::parse("/version"), Some(SlashCommand::Version));
+        assert_eq!(
+            SlashCommand::parse("/export notes.txt"),
+            Some(SlashCommand::Export {
+                path: Some("notes.txt".to_string())
+            })
+        );
+        assert_eq!(
+            SlashCommand::parse("/session switch abc123"),
+            Some(SlashCommand::Session {
+                action: Some("switch".to_string()),
+                target: Some("abc123".to_string())
+            })
+        );
+    }
+
+    #[test]
+    fn renders_help_from_shared_specs() {
+        let help = render_slash_command_help();
+        assert!(help.contains("works with --resume SESSION.json"));
+        assert!(help.contains("/help"));
+        assert!(help.contains("/status"));
+        assert!(help.contains("/compact"));
+        assert!(help.contains("/model [model]"));
+        assert!(help.contains("/permissions [read-only|workspace-write|danger-full-access]"));
+        assert!(help.contains("/clear [--confirm]"));
+        assert!(help.contains("/cost"));
+        assert!(help.contains("/resume <session-path>"));
+        assert!(help.contains("/config [env|hooks|model]"));
+        assert!(help.contains("/memory"));
+        assert!(help.contains("/init"));
+        assert!(help.contains("/diff"));
+        assert!(help.contains("/version"));
+        assert!(help.contains("/export [file]"));
+        assert!(help.contains("/session [list|switch <session-id>]"));
+        assert_eq!(slash_command_specs().len(), 15);
+        assert_eq!(resume_supported_slash_commands().len(), 11);
+    }
+
     #[test]
     fn compacts_sessions_via_slash_command() {
         let session = Session {
@@ -103,8 +421,52 @@ mod tests {
     }
 
     #[test]
-    fn ignores_unknown_slash_commands() {
+    fn help_command_is_non_mutating() {
+        let session = Session::new();
+        let result = handle_slash_command("/help", &session, CompactionConfig::default())
+            .expect("help command should be handled");
+        assert_eq!(result.session, session);
+        assert!(result.message.contains("Slash commands"));
+    }
+
+    #[test]
+    fn ignores_unknown_or_runtime_bound_slash_commands() {
         let session = Session::new();
         assert!(handle_slash_command("/unknown", &session, CompactionConfig::default()).is_none());
+        assert!(handle_slash_command("/status", &session, CompactionConfig::default()).is_none());
+        assert!(
+            handle_slash_command("/model claude", &session, CompactionConfig::default()).is_none()
+        );
+        assert!(handle_slash_command(
+            "/permissions read-only",
+            &session,
+            CompactionConfig::default()
+        )
+        .is_none());
+        assert!(handle_slash_command("/clear", &session, CompactionConfig::default()).is_none());
+        assert!(
+            handle_slash_command("/clear --confirm", &session, CompactionConfig::default())
+                .is_none()
+        );
+        assert!(handle_slash_command("/cost", &session, CompactionConfig::default()).is_none());
+        assert!(handle_slash_command(
+            "/resume session.json",
+            &session,
+            CompactionConfig::default()
+        )
+        .is_none());
+        assert!(handle_slash_command("/config", &session, CompactionConfig::default()).is_none());
+        assert!(
+            handle_slash_command("/config env", &session, CompactionConfig::default()).is_none()
+        );
+        assert!(handle_slash_command("/diff", &session, CompactionConfig::default()).is_none());
+        assert!(handle_slash_command("/version", &session, CompactionConfig::default()).is_none());
+        assert!(
+            handle_slash_command("/export note.txt", &session, CompactionConfig::default())
+                .is_none()
+        );
+        assert!(
+            handle_slash_command("/session list", &session, CompactionConfig::default()).is_none()
+        );
     }
 }

rust/crates/compat-harness/src/lib.rs

@@ -24,9 +24,10 @@ impl UpstreamPaths {
             .as_ref()
             .canonicalize()
             .unwrap_or_else(|_| workspace_dir.as_ref().to_path_buf());
-        let repo_root = workspace_dir
+        let primary_repo_root = workspace_dir
             .parent()
             .map_or_else(|| PathBuf::from(".."), Path::to_path_buf);
+        let repo_root = resolve_upstream_repo_root(&primary_repo_root);
         Self { repo_root }
     }
 
@@ -53,6 +54,42 @@ pub struct ExtractedManifest {
     pub bootstrap: BootstrapPlan,
 }
 
+fn resolve_upstream_repo_root(primary_repo_root: &Path) -> PathBuf {
+    let candidates = upstream_repo_candidates(primary_repo_root);
+    candidates
+        .into_iter()
+        .find(|candidate| candidate.join("src/commands.ts").is_file())
+        .unwrap_or_else(|| primary_repo_root.to_path_buf())
+}
+
+fn upstream_repo_candidates(primary_repo_root: &Path) -> Vec<PathBuf> {
+    let mut candidates = vec![primary_repo_root.to_path_buf()];
+
+    if let Some(explicit) = std::env::var_os("CLAUDE_CODE_UPSTREAM") {
+        candidates.push(PathBuf::from(explicit));
+    }
+
+    for ancestor in primary_repo_root.ancestors().take(4) {
+        candidates.push(ancestor.join("claude-code"));
+        candidates.push(ancestor.join("clawd-code"));
+    }
+
+    candidates.push(
+        primary_repo_root
+            .join("reference-source")
+            .join("claude-code"),
+    );
+    candidates.push(primary_repo_root.join("vendor").join("claude-code"));
+
+    let mut deduped = Vec::new();
+    for candidate in candidates {
+        if !deduped.iter().any(|seen: &PathBuf| seen == &candidate) {
+            deduped.push(candidate);
+        }
+    }
+    deduped
+}
+
 pub fn extract_manifest(paths: &UpstreamPaths) -> std::io::Result<ExtractedManifest> {
     let commands_source = fs::read_to_string(paths.commands_path())?;
     let tools_source = fs::read_to_string(paths.tools_path())?;
@@ -270,9 +307,19 @@ mod tests {
         UpstreamPaths::from_workspace_dir(workspace_dir)
     }
 
+    fn has_upstream_fixture(paths: &UpstreamPaths) -> bool {
+        paths.commands_path().is_file()
+            && paths.tools_path().is_file()
+            && paths.cli_path().is_file()
+    }
+
     #[test]
     fn extracts_non_empty_manifests_from_upstream_repo() {
-        let manifest = extract_manifest(&fixture_paths()).expect("manifest should load");
+        let paths = fixture_paths();
+        if !has_upstream_fixture(&paths) {
+            return;
+        }
+        let manifest = extract_manifest(&paths).expect("manifest should load");
         assert!(!manifest.commands.entries().is_empty());
         assert!(!manifest.tools.entries().is_empty());
         assert!(!manifest.bootstrap.phases().is_empty());
@@ -280,9 +327,12 @@ mod tests {
 
     #[test]
     fn detects_known_upstream_command_symbols() {
-        let commands = extract_commands(
+        let paths = fixture_paths();
-            &fs::read_to_string(fixture_paths().commands_path()).expect("commands.ts"),
+        if !paths.commands_path().is_file() {
-        );
+            return;
+        }
+        let commands =
+            extract_commands(&fs::read_to_string(paths.commands_path()).expect("commands.ts"));
         let names: Vec<_> = commands
             .entries()
             .iter()
@@ -295,8 +345,11 @@ mod tests {
 
     #[test]
     fn detects_known_upstream_tool_symbols() {
-        let tools =
+        let paths = fixture_paths();
-            extract_tools(&fs::read_to_string(fixture_paths().tools_path()).expect("tools.ts"));
+        if !paths.tools_path().is_file() {
+            return;
+        }
+        let tools = extract_tools(&fs::read_to_string(paths.tools_path()).expect("tools.ts"));
         let names: Vec<_> = tools
             .entries()
             .iter()

rust/crates/runtime/Cargo.toml

@@ -6,11 +6,12 @@ license.workspace = true
 publish.workspace = true
 
 [dependencies]
+sha2 = "0.10"
 glob = "0.3"
 regex = "1"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
-tokio = { version = "1", features = ["macros", "process", "rt", "rt-multi-thread", "time"] }
+tokio = { version = "1", features = ["io-util", "macros", "process", "rt", "rt-multi-thread", "time"] }
 walkdir = "2"
 
 [lints]

rust/crates/runtime/src/compact.rs

@@ -18,6 +18,7 @@ impl Default for CompactionConfig {
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct CompactionResult {
     pub summary: String,
+    pub formatted_summary: String,
     pub compacted_session: Session,
     pub removed_message_count: usize,
 }
@@ -75,6 +76,7 @@ pub fn compact_session(session: &Session, config: CompactionConfig) -> Compactio
     if !should_compact(session, config) {
         return CompactionResult {
             summary: String::new(),
+            formatted_summary: String::new(),
             compacted_session: session.clone(),
             removed_message_count: 0,
         };
@@ -87,6 +89,7 @@ pub fn compact_session(session: &Session, config: CompactionConfig) -> Compactio
     let removed = &session.messages[..keep_from];
     let preserved = session.messages[keep_from..].to_vec();
     let summary = summarize_messages(removed);
+    let formatted_summary = format_compact_summary(&summary);
     let continuation = get_compact_continuation_message(&summary, true, !preserved.is_empty());
 
     let mut compacted_messages = vec![ConversationMessage {
@@ -98,6 +101,7 @@ pub fn compact_session(session: &Session, config: CompactionConfig) -> Compactio
 
     CompactionResult {
         summary,
+        formatted_summary,
         compacted_session: Session {
             version: session.version,
             messages: compacted_messages,
@@ -107,7 +111,73 @@ pub fn compact_session(session: &Session, config: CompactionConfig) -> Compactio
 }
 
 fn summarize_messages(messages: &[ConversationMessage]) -> String {
-    let mut lines = vec!["<summary>".to_string(), "Conversation summary:".to_string()];
+    let user_messages = messages
+        .iter()
+        .filter(|message| message.role == MessageRole::User)
+        .count();
+    let assistant_messages = messages
+        .iter()
+        .filter(|message| message.role == MessageRole::Assistant)
+        .count();
+    let tool_messages = messages
+        .iter()
+        .filter(|message| message.role == MessageRole::Tool)
+        .count();
+
+    let mut tool_names = messages
+        .iter()
+        .flat_map(|message| message.blocks.iter())
+        .filter_map(|block| match block {
+            ContentBlock::ToolUse { name, .. } => Some(name.as_str()),
+            ContentBlock::ToolResult { tool_name, .. } => Some(tool_name.as_str()),
+            ContentBlock::Text { .. } => None,
+        })
+        .collect::<Vec<_>>();
+    tool_names.sort_unstable();
+    tool_names.dedup();
+
+    let mut lines = vec![
+        "<summary>".to_string(),
+        "Conversation summary:".to_string(),
+        format!(
+            "- Scope: {} earlier messages compacted (user={}, assistant={}, tool={}).",
+            messages.len(),
+            user_messages,
+            assistant_messages,
+            tool_messages
+        ),
+    ];
+
+    if !tool_names.is_empty() {
+        lines.push(format!("- Tools mentioned: {}.", tool_names.join(", ")));
+    }
+
+    let recent_user_requests = collect_recent_role_summaries(messages, MessageRole::User, 3);
+    if !recent_user_requests.is_empty() {
+        lines.push("- Recent user requests:".to_string());
+        lines.extend(
+            recent_user_requests
+                .into_iter()
+                .map(|request| format!("  - {request}")),
+        );
+    }
+
+    let pending_work = infer_pending_work(messages);
+    if !pending_work.is_empty() {
+        lines.push("- Pending work:".to_string());
+        lines.extend(pending_work.into_iter().map(|item| format!("  - {item}")));
+    }
+
+    let key_files = collect_key_files(messages);
+    if !key_files.is_empty() {
+        lines.push(format!("- Key files referenced: {}.", key_files.join(", ")));
+    }
+
+    if let Some(current_work) = infer_current_work(messages) {
+        lines.push(format!("- Current work: {current_work}"));
+    }
+
+    lines.push("- Key timeline:".to_string());
     for message in messages {
         let role = match message.role {
             MessageRole::System => "system",
@@ -121,7 +191,7 @@ fn summarize_messages(messages: &[ConversationMessage]) -> String {
             .map(summarize_block)
             .collect::<Vec<_>>()
             .join(" | ");
-        lines.push(format!("- {role}: {content}"));
+        lines.push(format!("  - {role}: {content}"));
     }
     lines.push("</summary>".to_string());
     lines.join("\n")
@@ -144,6 +214,106 @@ fn summarize_block(block: &ContentBlock) -> String {
     truncate_summary(&raw, 160)
 }
 
+fn collect_recent_role_summaries(
+    messages: &[ConversationMessage],
+    role: MessageRole,
+    limit: usize,
+) -> Vec<String> {
+    messages
+        .iter()
+        .filter(|message| message.role == role)
+        .rev()
+        .filter_map(|message| first_text_block(message))
+        .take(limit)
+        .map(|text| truncate_summary(text, 160))
+        .collect::<Vec<_>>()
+        .into_iter()
+        .rev()
+        .collect()
+}
+
+fn infer_pending_work(messages: &[ConversationMessage]) -> Vec<String> {
+    messages
+        .iter()
+        .rev()
+        .filter_map(first_text_block)
+        .filter(|text| {
+            let lowered = text.to_ascii_lowercase();
+            lowered.contains("todo")
+                || lowered.contains("next")
+                || lowered.contains("pending")
+                || lowered.contains("follow up")
+                || lowered.contains("remaining")
+        })
+        .take(3)
+        .map(|text| truncate_summary(text, 160))
+        .collect::<Vec<_>>()
+        .into_iter()
+        .rev()
+        .collect()
+}
+
+fn collect_key_files(messages: &[ConversationMessage]) -> Vec<String> {
+    let mut files = messages
+        .iter()
+        .flat_map(|message| message.blocks.iter())
+        .map(|block| match block {
+            ContentBlock::Text { text } => text.as_str(),
+            ContentBlock::ToolUse { input, .. } => input.as_str(),
+            ContentBlock::ToolResult { output, .. } => output.as_str(),
+        })
+        .flat_map(extract_file_candidates)
+        .collect::<Vec<_>>();
+    files.sort();
+    files.dedup();
+    files.into_iter().take(8).collect()
+}
+
+fn infer_current_work(messages: &[ConversationMessage]) -> Option<String> {
+    messages
+        .iter()
+        .rev()
+        .filter_map(first_text_block)
+        .find(|text| !text.trim().is_empty())
+        .map(|text| truncate_summary(text, 200))
+}
+
+fn first_text_block(message: &ConversationMessage) -> Option<&str> {
+    message.blocks.iter().find_map(|block| match block {
+        ContentBlock::Text { text } if !text.trim().is_empty() => Some(text.as_str()),
+        ContentBlock::ToolUse { .. }
+        | ContentBlock::ToolResult { .. }
+        | ContentBlock::Text { .. } => None,
+    })
+}
+
+fn has_interesting_extension(candidate: &str) -> bool {
+    std::path::Path::new(candidate)
+        .extension()
+        .and_then(|extension| extension.to_str())
+        .is_some_and(|extension| {
+            ["rs", "ts", "tsx", "js", "json", "md"]
+                .iter()
+                .any(|expected| extension.eq_ignore_ascii_case(expected))
+        })
+}
+
+fn extract_file_candidates(content: &str) -> Vec<String> {
+    content
+        .split_whitespace()
+        .filter_map(|token| {
+            let candidate = token.trim_matches(|char: char| {
+                matches!(char, ',' | '.' | ':' | ';' | ')' | '(' | '"' | '\'' | '`')
+            });
+            if candidate.contains('/') && has_interesting_extension(candidate) {
+                Some(candidate.to_string())
+            } else {
+                None
+            }
+        })
+        .collect()
+}
+
 fn truncate_summary(content: &str, max_chars: usize) -> String {
     if content.chars().count() <= max_chars {
         return content.to_string();
@@ -207,8 +377,8 @@ fn collapse_blank_lines(content: &str) -> String {
 #[cfg(test)]
 mod tests {
     use super::{
-        compact_session, estimate_session_tokens, format_compact_summary, should_compact,
+        collect_key_files, compact_session, estimate_session_tokens, format_compact_summary,
-        CompactionConfig,
+        infer_pending_work, should_compact, CompactionConfig,
     };
     use crate::session::{ContentBlock, ConversationMessage, MessageRole, Session};
 
@@ -229,6 +399,7 @@ mod tests {
         assert_eq!(result.removed_message_count, 0);
         assert_eq!(result.compacted_session, session);
         assert!(result.summary.is_empty());
+        assert!(result.formatted_summary.is_empty());
     }
 
     #[test]
@@ -268,6 +439,8 @@ mod tests {
             &result.compacted_session.messages[0].blocks[0],
             ContentBlock::Text { text } if text.contains("Summary:")
         ));
+        assert!(result.formatted_summary.contains("Scope:"));
+        assert!(result.formatted_summary.contains("Key timeline:"));
         assert!(should_compact(
             &session,
             CompactionConfig {
@@ -288,4 +461,25 @@ mod tests {
         assert!(summary.ends_with('…'));
         assert!(summary.chars().count() <= 161);
     }
+
+    #[test]
+    fn extracts_key_files_from_message_content() {
+        let files = collect_key_files(&[ConversationMessage::user_text(
+            "Update rust/crates/runtime/src/compact.rs and rust/crates/rusty-claude-cli/src/main.rs next.",
+        )]);
+        assert!(files.contains(&"rust/crates/runtime/src/compact.rs".to_string()));
+        assert!(files.contains(&"rust/crates/rusty-claude-cli/src/main.rs".to_string()));
+    }
+
+    #[test]
+    fn infers_pending_work_from_recent_messages() {
+        let pending = infer_pending_work(&[
+            ConversationMessage::user_text("done"),
+            ConversationMessage::assistant(vec![ContentBlock::Text {
+                text: "Next: update tests and follow up on remaining CLI polish.".to_string(),
+            }]),
+        ]);
+        assert_eq!(pending.len(), 1);
+        assert!(pending[0].contains("Next: update tests"));
+    }
 }

rust/crates/runtime/src/config.rs

@@ -14,6 +14,13 @@ pub enum ConfigSource {
     Local,
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ResolvedPermissionMode {
+    ReadOnly,
+    WorkspaceWrite,
+    DangerFullAccess,
+}
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct ConfigEntry {
     pub source: ConfigSource,
@@ -31,6 +38,8 @@ pub struct RuntimeConfig {
 pub struct RuntimeFeatureConfig {
     mcp: McpConfigCollection,
     oauth: Option<OAuthConfig>,
+    model: Option<String>,
+    permission_mode: Option<ResolvedPermissionMode>,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Default)]
@@ -165,11 +174,23 @@ impl ConfigLoader {
 
     #[must_use]
     pub fn discover(&self) -> Vec<ConfigEntry> {
+        let user_legacy_path = self.config_home.parent().map_or_else(
+            || PathBuf::from(".claude.json"),
+            |parent| parent.join(".claude.json"),
+        );
         vec![
+            ConfigEntry {
+                source: ConfigSource::User,
+                path: user_legacy_path,
+            },
             ConfigEntry {
                 source: ConfigSource::User,
                 path: self.config_home.join("settings.json"),
             },
+            ConfigEntry {
+                source: ConfigSource::Project,
+                path: self.cwd.join(".claude.json"),
+            },
             ConfigEntry {
                 source: ConfigSource::Project,
                 path: self.cwd.join(".claude").join("settings.json"),
@@ -195,14 +216,15 @@ impl ConfigLoader {
             loaded_entries.push(entry);
         }
 
+        let merged_value = JsonValue::Object(merged.clone());
+
         let feature_config = RuntimeFeatureConfig {
             mcp: McpConfigCollection {
                 servers: mcp_servers,
             },
-            oauth: parse_optional_oauth_config(
+            oauth: parse_optional_oauth_config(&merged_value, "merged settings.oauth")?,
-                &JsonValue::Object(merged.clone()),
+            model: parse_optional_model(&merged_value),
-                "merged settings.oauth",
+            permission_mode: parse_optional_permission_mode(&merged_value)?,
-            )?,
         };
 
         Ok(RuntimeConfig {
@@ -257,6 +279,16 @@ impl RuntimeConfig {
     pub fn oauth(&self) -> Option<&OAuthConfig> {
         self.feature_config.oauth.as_ref()
     }
+
+    #[must_use]
+    pub fn model(&self) -> Option<&str> {
+        self.feature_config.model.as_deref()
+    }
+
+    #[must_use]
+    pub fn permission_mode(&self) -> Option<ResolvedPermissionMode> {
+        self.feature_config.permission_mode
+    }
 }
 
 impl RuntimeFeatureConfig {
@@ -269,6 +301,16 @@ impl RuntimeFeatureConfig {
     pub fn oauth(&self) -> Option<&OAuthConfig> {
         self.oauth.as_ref()
     }
+
+    #[must_use]
+    pub fn model(&self) -> Option<&str> {
+        self.model.as_deref()
+    }
+
+    #[must_use]
+    pub fn permission_mode(&self) -> Option<ResolvedPermissionMode> {
+        self.permission_mode
+    }
 }
 
 impl McpConfigCollection {
@@ -307,6 +349,7 @@ impl McpServerConfig {
 fn read_optional_json_object(
     path: &Path,
 ) -> Result<Option<BTreeMap<String, JsonValue>>, ConfigError> {
+    let is_legacy_config = path.file_name().and_then(|name| name.to_str()) == Some(".claude.json");
     let contents = match fs::read_to_string(path) {
         Ok(contents) => contents,
         Err(error) if error.kind() == std::io::ErrorKind::NotFound => return Ok(None),
@@ -317,14 +360,20 @@ fn read_optional_json_object(
         return Ok(Some(BTreeMap::new()));
     }
 
-    let parsed = JsonValue::parse(&contents)
+    let parsed = match JsonValue::parse(&contents) {
-        .map_err(|error| ConfigError::Parse(format!("{}: {error}", path.display())))?;
+        Ok(parsed) => parsed,
-    let object = parsed.as_object().ok_or_else(|| {
+        Err(error) if is_legacy_config => return Ok(None),
-        ConfigError::Parse(format!(
+        Err(error) => return Err(ConfigError::Parse(format!("{}: {error}", path.display()))),
+    };
+    let Some(object) = parsed.as_object() else {
+        if is_legacy_config {
+            return Ok(None);
+        }
+        return Err(ConfigError::Parse(format!(
             "{}: top-level settings value must be a JSON object",
             path.display()
-        ))
+        )));
-    })?;
+    };
     Ok(Some(object.clone()))
 }
 
@@ -355,6 +404,47 @@ fn merge_mcp_servers(
     Ok(())
 }
 
+fn parse_optional_model(root: &JsonValue) -> Option<String> {
+    root.as_object()
+        .and_then(|object| object.get("model"))
+        .and_then(JsonValue::as_str)
+        .map(ToOwned::to_owned)
+}
+
+fn parse_optional_permission_mode(
+    root: &JsonValue,
+) -> Result<Option<ResolvedPermissionMode>, ConfigError> {
+    let Some(object) = root.as_object() else {
+        return Ok(None);
+    };
+    if let Some(mode) = object.get("permissionMode").and_then(JsonValue::as_str) {
+        return parse_permission_mode_label(mode, "merged settings.permissionMode").map(Some);
+    }
+    let Some(mode) = object
+        .get("permissions")
+        .and_then(JsonValue::as_object)
+        .and_then(|permissions| permissions.get("defaultMode"))
+        .and_then(JsonValue::as_str)
+    else {
+        return Ok(None);
+    };
+    parse_permission_mode_label(mode, "merged settings.permissions.defaultMode").map(Some)
+}
+
+fn parse_permission_mode_label(
+    mode: &str,
+    context: &str,
+) -> Result<ResolvedPermissionMode, ConfigError> {
+    match mode {
+        "default" | "plan" | "read-only" => Ok(ResolvedPermissionMode::ReadOnly),
+        "acceptEdits" | "auto" | "workspace-write" => Ok(ResolvedPermissionMode::WorkspaceWrite),
+        "dontAsk" | "danger-full-access" => Ok(ResolvedPermissionMode::DangerFullAccess),
+        other => Err(ConfigError::Parse(format!(
+            "{context}: unsupported permission mode {other}"
+        ))),
+    }
+}
+
 fn parse_optional_oauth_config(
     root: &JsonValue,
     context: &str,
@@ -594,7 +684,8 @@ fn deep_merge_objects(
 #[cfg(test)]
 mod tests {
     use super::{
-        ConfigLoader, ConfigSource, McpServerConfig, McpTransport, CLAUDE_CODE_SETTINGS_SCHEMA_NAME,
+        ConfigLoader, ConfigSource, McpServerConfig, McpTransport, ResolvedPermissionMode,
+        CLAUDE_CODE_SETTINGS_SCHEMA_NAME,
     };
     use crate::json::JsonValue;
     use std::fs;
@@ -635,14 +726,24 @@ mod tests {
         fs::create_dir_all(cwd.join(".claude")).expect("project config dir");
         fs::create_dir_all(&home).expect("home config dir");
 
+        fs::write(
+            home.parent().expect("home parent").join(".claude.json"),
+            r#"{"model":"haiku","env":{"A":"1"},"mcpServers":{"home":{"command":"uvx","args":["home"]}}}"#,
+        )
+        .expect("write user compat config");
         fs::write(
             home.join("settings.json"),
-            r#"{"model":"sonnet","env":{"A":"1"},"hooks":{"PreToolUse":["base"]}}"#,
+            r#"{"model":"sonnet","env":{"A2":"1"},"hooks":{"PreToolUse":["base"]},"permissions":{"defaultMode":"plan"}}"#,
         )
         .expect("write user settings");
+        fs::write(
+            cwd.join(".claude.json"),
+            r#"{"model":"project-compat","env":{"B":"2"}}"#,
+        )
+        .expect("write project compat config");
         fs::write(
             cwd.join(".claude").join("settings.json"),
-            r#"{"env":{"B":"2"},"hooks":{"PostToolUse":["project"]}}"#,
+            r#"{"env":{"C":"3"},"hooks":{"PostToolUse":["project"]},"mcpServers":{"project":{"command":"uvx","args":["project"]}}}"#,
         )
         .expect("write project settings");
         fs::write(
@@ -656,25 +757,37 @@ mod tests {
             .expect("config should load");
 
         assert_eq!(CLAUDE_CODE_SETTINGS_SCHEMA_NAME, "SettingsSchema");
-        assert_eq!(loaded.loaded_entries().len(), 3);
+        assert_eq!(loaded.loaded_entries().len(), 5);
         assert_eq!(loaded.loaded_entries()[0].source, ConfigSource::User);
         assert_eq!(
             loaded.get("model"),
             Some(&JsonValue::String("opus".to_string()))
         );
+        assert_eq!(loaded.model(), Some("opus"));
+        assert_eq!(
+            loaded.permission_mode(),
+            Some(ResolvedPermissionMode::WorkspaceWrite)
+        );
         assert_eq!(
             loaded
                 .get("env")
                 .and_then(JsonValue::as_object)
                 .expect("env object")
                 .len(),
-            2
+            4
         );
         assert!(loaded
             .get("hooks")
             .and_then(JsonValue::as_object)
             .expect("hooks object")
             .contains_key("PreToolUse"));
+        assert!(loaded
+            .get("hooks")
+            .and_then(JsonValue::as_object)
+            .expect("hooks object")
+            .contains_key("PostToolUse"));
+        assert!(loaded.mcp().get("home").is_some());
+        assert!(loaded.mcp().get("project").is_some());
 
         fs::remove_dir_all(root).expect("cleanup temp dir");
     }

rust/crates/runtime/src/conversation.rs

@@ -408,7 +408,7 @@ mod tests {
                 .sum::<i32>();
             Ok(total.to_string())
         });
-        let permission_policy = PermissionPolicy::new(PermissionMode::Prompt);
+        let permission_policy = PermissionPolicy::new(PermissionMode::WorkspaceWrite);
         let system_prompt = SystemPromptBuilder::new()
             .with_project_context(ProjectContext {
                 cwd: PathBuf::from("/tmp/project"),
@@ -487,7 +487,7 @@ mod tests {
             Session::new(),
             SingleCallApiClient,
             StaticToolExecutor::new(),
-            PermissionPolicy::new(PermissionMode::Prompt),
+            PermissionPolicy::new(PermissionMode::WorkspaceWrite),
             vec!["system".to_string()],
         );
 
@@ -536,7 +536,7 @@ mod tests {
             session,
             SimpleApi,
             StaticToolExecutor::new(),
-            PermissionPolicy::new(PermissionMode::Allow),
+            PermissionPolicy::new(PermissionMode::DangerFullAccess),
             vec!["system".to_string()],
         );
 
@@ -563,7 +563,7 @@ mod tests {
             Session::new(),
             SimpleApi,
             StaticToolExecutor::new(),
-            PermissionPolicy::new(PermissionMode::Allow),
+            PermissionPolicy::new(PermissionMode::DangerFullAccess),
             vec!["system".to_string()],
         );
         runtime.run_turn("a", None).expect("turn a");

rust/crates/runtime/src/file_ops.rs

@@ -296,12 +296,12 @@ pub fn grep_search(input: &GrepSearchInput) -> io::Result<GrepSearchOutput> {
             continue;
         }
 
-        let Ok(file_content) = fs::read_to_string(&file_path) else {
+        let Ok(file_contents) = fs::read_to_string(&file_path) else {
             continue;
         };
 
         if output_mode == "count" {
-            let count = regex.find_iter(&file_content).count();
+            let count = regex.find_iter(&file_contents).count();
             if count > 0 {
                 filenames.push(file_path.to_string_lossy().into_owned());
                 total_matches += count;
@@ -309,7 +309,7 @@ pub fn grep_search(input: &GrepSearchInput) -> io::Result<GrepSearchOutput> {
             continue;
         }
 
-        let lines: Vec<&str> = file_content.lines().collect();
+        let lines: Vec<&str> = file_contents.lines().collect();
         let mut matched_lines = Vec::new();
         for (index, line) in lines.iter().enumerate() {
             if regex.is_match(line) {
@@ -327,13 +327,13 @@ pub fn grep_search(input: &GrepSearchInput) -> io::Result<GrepSearchOutput> {
             for index in matched_lines {
                 let start = index.saturating_sub(input.before.unwrap_or(context));
                 let end = (index + input.after.unwrap_or(context) + 1).min(lines.len());
-                for (current, line_content) in lines.iter().enumerate().take(end).skip(start) {
+                for (current, line) in lines.iter().enumerate().take(end).skip(start) {
                     let prefix = if input.line_numbers.unwrap_or(true) {
                         format!("{}:{}:", file_path.to_string_lossy(), current + 1)
                     } else {
                         format!("{}:", file_path.to_string_lossy())
                     };
-                    content_lines.push(format!("{prefix}{line_content}"));
+                    content_lines.push(format!("{prefix}{line}"));
                 }
             }
         }
@@ -341,7 +341,7 @@ pub fn grep_search(input: &GrepSearchInput) -> io::Result<GrepSearchOutput> {
 
     let (filenames, applied_limit, applied_offset) =
         apply_limit(filenames, input.head_limit, input.offset);
-    let rendered_content = if output_mode == "content" {
+    let content_output = if output_mode == "content" {
         let (lines, limit, offset) = apply_limit(content_lines, input.head_limit, input.offset);
         return Ok(GrepSearchOutput {
             mode: Some(output_mode),
@@ -361,7 +361,7 @@ pub fn grep_search(input: &GrepSearchInput) -> io::Result<GrepSearchOutput> {
         mode: Some(output_mode.clone()),
         num_files: filenames.len(),
         filenames,
-        content: rendered_content,
+        content: content_output,
         num_lines: None,
         num_matches: (output_mode == "count").then_some(total_matches),
         applied_limit,

rust/crates/runtime/src/lib.rs

@@ -5,8 +5,13 @@ mod config;
 mod conversation;
 mod file_ops;
 mod json;
+mod mcp;
+mod mcp_client;
+mod mcp_stdio;
+mod oauth;
 mod permissions;
 mod prompt;
+mod remote;
 mod session;
 mod usage;
 
@@ -20,7 +25,8 @@ pub use config::{
     ConfigEntry, ConfigError, ConfigLoader, ConfigSource, McpClaudeAiProxyServerConfig,
     McpConfigCollection, McpOAuthConfig, McpRemoteServerConfig, McpSdkServerConfig,
     McpServerConfig, McpStdioServerConfig, McpTransport, McpWebSocketServerConfig, OAuthConfig,
-    RuntimeConfig, RuntimeFeatureConfig, ScopedMcpServerConfig, CLAUDE_CODE_SETTINGS_SCHEMA_NAME,
+    ResolvedPermissionMode, RuntimeConfig, RuntimeFeatureConfig, ScopedMcpServerConfig,
+    CLAUDE_CODE_SETTINGS_SCHEMA_NAME,
 };
 pub use conversation::{
     ApiClient, ApiRequest, AssistantEvent, ConversationRuntime, RuntimeError, StaticToolExecutor,
@@ -31,6 +37,29 @@ pub use file_ops::{
     GrepSearchInput, GrepSearchOutput, ReadFileOutput, StructuredPatchHunk, TextFilePayload,
     WriteFileOutput,
 };
+pub use mcp::{
+    mcp_server_signature, mcp_tool_name, mcp_tool_prefix, normalize_name_for_mcp,
+    scoped_mcp_config_hash, unwrap_ccr_proxy_url,
+};
+pub use mcp_client::{
+    McpClaudeAiProxyTransport, McpClientAuth, McpClientBootstrap, McpClientTransport,
+    McpRemoteTransport, McpSdkTransport, McpStdioTransport,
+};
+pub use mcp_stdio::{
+    spawn_mcp_stdio_process, JsonRpcError, JsonRpcId, JsonRpcRequest, JsonRpcResponse,
+    ManagedMcpTool, McpInitializeClientInfo, McpInitializeParams, McpInitializeResult,
+    McpInitializeServerInfo, McpListResourcesParams, McpListResourcesResult, McpListToolsParams,
+    McpListToolsResult, McpReadResourceParams, McpReadResourceResult, McpResource,
+    McpResourceContents, McpServerManager, McpServerManagerError, McpStdioProcess, McpTool,
+    McpToolCallContent, McpToolCallParams, McpToolCallResult, UnsupportedMcpServer,
+};
+pub use oauth::{
+    clear_oauth_credentials, code_challenge_s256, credentials_path, generate_pkce_pair,
+    generate_state, load_oauth_credentials, loopback_redirect_uri, parse_oauth_callback_query,
+    parse_oauth_callback_request_target, save_oauth_credentials, OAuthAuthorizationRequest,
+    OAuthCallbackParams, OAuthRefreshRequest, OAuthTokenExchangeRequest, OAuthTokenSet,
+    PkceChallengeMethod, PkceCodePair,
+};
 pub use permissions::{
     PermissionMode, PermissionOutcome, PermissionPolicy, PermissionPromptDecision,
     PermissionPrompter, PermissionRequest,
@@ -39,5 +68,20 @@ pub use prompt::{
     load_system_prompt, prepend_bullets, ContextFile, ProjectContext, PromptBuildError,
     SystemPromptBuilder, FRONTIER_MODEL_NAME, SYSTEM_PROMPT_DYNAMIC_BOUNDARY,
 };
+pub use remote::{
+    inherited_upstream_proxy_env, no_proxy_list, read_token, upstream_proxy_ws_url,
+    RemoteSessionContext, UpstreamProxyBootstrap, UpstreamProxyState, DEFAULT_REMOTE_BASE_URL,
+    DEFAULT_SESSION_TOKEN_PATH, DEFAULT_SYSTEM_CA_BUNDLE, NO_PROXY_HOSTS, UPSTREAM_PROXY_ENV_KEYS,
+};
 pub use session::{ContentBlock, ConversationMessage, MessageRole, Session, SessionError};
-pub use usage::{TokenUsage, UsageTracker};
+pub use usage::{
+    format_usd, pricing_for_model, ModelPricing, TokenUsage, UsageCostEstimate, UsageTracker,
+};
+
+#[cfg(test)]
+pub(crate) fn test_env_lock() -> std::sync::MutexGuard<'static, ()> {
+    static LOCK: std::sync::OnceLock<std::sync::Mutex<()>> = std::sync::OnceLock::new();
+    LOCK.get_or_init(|| std::sync::Mutex::new(()))
+        .lock()
+        .unwrap_or_else(std::sync::PoisonError::into_inner)
+}

rust/crates/runtime/src/mcp.rs

@@ -0,0 +1,300 @@
+use crate::config::{McpServerConfig, ScopedMcpServerConfig};
+
+const CLAUDEAI_SERVER_PREFIX: &str = "claude.ai ";
+const CCR_PROXY_PATH_MARKERS: [&str; 2] = ["/v2/session_ingress/shttp/mcp/", "/v2/ccr-sessions/"];
+
+#[must_use]
+pub fn normalize_name_for_mcp(name: &str) -> String {
+    let mut normalized = name
+        .chars()
+        .map(|ch| match ch {
+            'a'..='z' | 'A'..='Z' | '0'..='9' | '_' | '-' => ch,
+            _ => '_',
+        })
+        .collect::<String>();
+
+    if name.starts_with(CLAUDEAI_SERVER_PREFIX) {
+        normalized = collapse_underscores(&normalized)
+            .trim_matches('_')
+            .to_string();
+    }
+
+    normalized
+}
+
+#[must_use]
+pub fn mcp_tool_prefix(server_name: &str) -> String {
+    format!("mcp__{}__", normalize_name_for_mcp(server_name))
+}
+
+#[must_use]
+pub fn mcp_tool_name(server_name: &str, tool_name: &str) -> String {
+    format!(
+        "{}{}",
+        mcp_tool_prefix(server_name),
+        normalize_name_for_mcp(tool_name)
+    )
+}
+
+#[must_use]
+pub fn unwrap_ccr_proxy_url(url: &str) -> String {
+    if !CCR_PROXY_PATH_MARKERS
+        .iter()
+        .any(|marker| url.contains(marker))
+    {
+        return url.to_string();
+    }
+
+    let Some(query_start) = url.find('?') else {
+        return url.to_string();
+    };
+    let query = &url[query_start + 1..];
+    for pair in query.split('&') {
+        let mut parts = pair.splitn(2, '=');
+        if matches!(parts.next(), Some("mcp_url")) {
+            if let Some(value) = parts.next() {
+                return percent_decode(value);
+            }
+        }
+    }
+
+    url.to_string()
+}
+
+#[must_use]
+pub fn mcp_server_signature(config: &McpServerConfig) -> Option<String> {
+    match config {
+        McpServerConfig::Stdio(config) => {
+            let mut command = vec![config.command.clone()];
+            command.extend(config.args.clone());
+            Some(format!("stdio:{}", render_command_signature(&command)))
+        }
+        McpServerConfig::Sse(config) | McpServerConfig::Http(config) => {
+            Some(format!("url:{}", unwrap_ccr_proxy_url(&config.url)))
+        }
+        McpServerConfig::Ws(config) => Some(format!("url:{}", unwrap_ccr_proxy_url(&config.url))),
+        McpServerConfig::ClaudeAiProxy(config) => {
+            Some(format!("url:{}", unwrap_ccr_proxy_url(&config.url)))
+        }
+        McpServerConfig::Sdk(_) => None,
+    }
+}
+
+#[must_use]
+pub fn scoped_mcp_config_hash(config: &ScopedMcpServerConfig) -> String {
+    let rendered = match &config.config {
+        McpServerConfig::Stdio(stdio) => format!(
+            "stdio|{}|{}|{}",
+            stdio.command,
+            render_command_signature(&stdio.args),
+            render_env_signature(&stdio.env)
+        ),
+        McpServerConfig::Sse(remote) => format!(
+            "sse|{}|{}|{}|{}",
+            remote.url,
+            render_env_signature(&remote.headers),
+            remote.headers_helper.as_deref().unwrap_or(""),
+            render_oauth_signature(remote.oauth.as_ref())
+        ),
+        McpServerConfig::Http(remote) => format!(
+            "http|{}|{}|{}|{}",
+            remote.url,
+            render_env_signature(&remote.headers),
+            remote.headers_helper.as_deref().unwrap_or(""),
+            render_oauth_signature(remote.oauth.as_ref())
+        ),
+        McpServerConfig::Ws(ws) => format!(
+            "ws|{}|{}|{}",
+            ws.url,
+            render_env_signature(&ws.headers),
+            ws.headers_helper.as_deref().unwrap_or("")
+        ),
+        McpServerConfig::Sdk(sdk) => format!("sdk|{}", sdk.name),
+        McpServerConfig::ClaudeAiProxy(proxy) => {
+            format!("claudeai-proxy|{}|{}", proxy.url, proxy.id)
+        }
+    };
+    stable_hex_hash(&rendered)
+}
+
+fn render_command_signature(command: &[String]) -> String {
+    let escaped = command
+        .iter()
+        .map(|part| part.replace('\\', "\\\\").replace('|', "\\|"))
+        .collect::<Vec<_>>();
+    format!("[{}]", escaped.join("|"))
+}
+
+fn render_env_signature(map: &std::collections::BTreeMap<String, String>) -> String {
+    map.iter()
+        .map(|(key, value)| format!("{key}={value}"))
+        .collect::<Vec<_>>()
+        .join(";")
+}
+
+fn render_oauth_signature(oauth: Option<&crate::config::McpOAuthConfig>) -> String {
+    oauth.map_or_else(String::new, |oauth| {
+        format!(
+            "{}|{}|{}|{}",
+            oauth.client_id.as_deref().unwrap_or(""),
+            oauth
+                .callback_port
+                .map_or_else(String::new, |port| port.to_string()),
+            oauth.auth_server_metadata_url.as_deref().unwrap_or(""),
+            oauth.xaa.map_or_else(String::new, |flag| flag.to_string())
+        )
+    })
+}
+
+fn stable_hex_hash(value: &str) -> String {
+    let mut hash = 0xcbf2_9ce4_8422_2325_u64;
+    for byte in value.as_bytes() {
+        hash ^= u64::from(*byte);
+        hash = hash.wrapping_mul(0x0100_0000_01b3);
+    }
+    format!("{hash:016x}")
+}
+
+fn collapse_underscores(value: &str) -> String {
+    let mut collapsed = String::with_capacity(value.len());
+    let mut last_was_underscore = false;
+    for ch in value.chars() {
+        if ch == '_' {
+            if !last_was_underscore {
+                collapsed.push(ch);
+            }
+            last_was_underscore = true;
+        } else {
+            collapsed.push(ch);
+            last_was_underscore = false;
+        }
+    }
+    collapsed
+}
+
+fn percent_decode(value: &str) -> String {
+    let bytes = value.as_bytes();
+    let mut decoded = Vec::with_capacity(bytes.len());
+    let mut index = 0;
+    while index < bytes.len() {
+        match bytes[index] {
+            b'%' if index + 2 < bytes.len() => {
+                let hex = &value[index + 1..index + 3];
+                if let Ok(byte) = u8::from_str_radix(hex, 16) {
+                    decoded.push(byte);
+                    index += 3;
+                    continue;
+                }
+                decoded.push(bytes[index]);
+                index += 1;
+            }
+            b'+' => {
+                decoded.push(b' ');
+                index += 1;
+            }
+            byte => {
+                decoded.push(byte);
+                index += 1;
+            }
+        }
+    }
+    String::from_utf8_lossy(&decoded).into_owned()
+}
+
+#[cfg(test)]
+mod tests {
+    use std::collections::BTreeMap;
+
+    use crate::config::{
+        ConfigSource, McpRemoteServerConfig, McpServerConfig, McpStdioServerConfig,
+        McpWebSocketServerConfig, ScopedMcpServerConfig,
+    };
+
+    use super::{
+        mcp_server_signature, mcp_tool_name, normalize_name_for_mcp, scoped_mcp_config_hash,
+        unwrap_ccr_proxy_url,
+    };
+
+    #[test]
+    fn normalizes_server_names_for_mcp_tooling() {
+        assert_eq!(normalize_name_for_mcp("github.com"), "github_com");
+        assert_eq!(normalize_name_for_mcp("tool name!"), "tool_name_");
+        assert_eq!(
+            normalize_name_for_mcp("claude.ai Example   Server!!"),
+            "claude_ai_Example_Server"
+        );
+        assert_eq!(
+            mcp_tool_name("claude.ai Example Server", "weather tool"),
+            "mcp__claude_ai_Example_Server__weather_tool"
+        );
+    }
+
+    #[test]
+    fn unwraps_ccr_proxy_urls_for_signature_matching() {
+        let wrapped = "https://api.anthropic.com/v2/session_ingress/shttp/mcp/123?mcp_url=https%3A%2F%2Fvendor.example%2Fmcp&other=1";
+        assert_eq!(unwrap_ccr_proxy_url(wrapped), "https://vendor.example/mcp");
+        assert_eq!(
+            unwrap_ccr_proxy_url("https://vendor.example/mcp"),
+            "https://vendor.example/mcp"
+        );
+    }
+
+    #[test]
+    fn computes_signatures_for_stdio_and_remote_servers() {
+        let stdio = McpServerConfig::Stdio(McpStdioServerConfig {
+            command: "uvx".to_string(),
+            args: vec!["mcp-server".to_string()],
+            env: BTreeMap::from([("TOKEN".to_string(), "secret".to_string())]),
+        });
+        assert_eq!(
+            mcp_server_signature(&stdio),
+            Some("stdio:[uvx|mcp-server]".to_string())
+        );
+
+        let remote = McpServerConfig::Ws(McpWebSocketServerConfig {
+            url: "https://api.anthropic.com/v2/ccr-sessions/1?mcp_url=wss%3A%2F%2Fvendor.example%2Fmcp".to_string(),
+            headers: BTreeMap::new(),
+            headers_helper: None,
+        });
+        assert_eq!(
+            mcp_server_signature(&remote),
+            Some("url:wss://vendor.example/mcp".to_string())
+        );
+    }
+
+    #[test]
+    fn scoped_hash_ignores_scope_but_tracks_config_content() {
+        let base_config = McpServerConfig::Http(McpRemoteServerConfig {
+            url: "https://vendor.example/mcp".to_string(),
+            headers: BTreeMap::from([("Authorization".to_string(), "Bearer token".to_string())]),
+            headers_helper: Some("helper.sh".to_string()),
+            oauth: None,
+        });
+        let user = ScopedMcpServerConfig {
+            scope: ConfigSource::User,
+            config: base_config.clone(),
+        };
+        let local = ScopedMcpServerConfig {
+            scope: ConfigSource::Local,
+            config: base_config,
+        };
+        assert_eq!(
+            scoped_mcp_config_hash(&user),
+            scoped_mcp_config_hash(&local)
+        );
+
+        let changed = ScopedMcpServerConfig {
+            scope: ConfigSource::Local,
+            config: McpServerConfig::Http(McpRemoteServerConfig {
+                url: "https://vendor.example/v2/mcp".to_string(),
+                headers: BTreeMap::new(),
+                headers_helper: None,
+                oauth: None,
+            }),
+        };
+        assert_ne!(
+            scoped_mcp_config_hash(&user),
+            scoped_mcp_config_hash(&changed)
+        );
+    }
+}

rust/crates/runtime/src/mcp_client.rs

@@ -0,0 +1,236 @@
+use std::collections::BTreeMap;
+
+use crate::config::{McpOAuthConfig, McpServerConfig, ScopedMcpServerConfig};
+use crate::mcp::{mcp_server_signature, mcp_tool_prefix, normalize_name_for_mcp};
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum McpClientTransport {
+    Stdio(McpStdioTransport),
+    Sse(McpRemoteTransport),
+    Http(McpRemoteTransport),
+    WebSocket(McpRemoteTransport),
+    Sdk(McpSdkTransport),
+    ClaudeAiProxy(McpClaudeAiProxyTransport),
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct McpStdioTransport {
+    pub command: String,
+    pub args: Vec<String>,
+    pub env: BTreeMap<String, String>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct McpRemoteTransport {
+    pub url: String,
+    pub headers: BTreeMap<String, String>,
+    pub headers_helper: Option<String>,
+    pub auth: McpClientAuth,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct McpSdkTransport {
+    pub name: String,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct McpClaudeAiProxyTransport {
+    pub url: String,
+    pub id: String,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum McpClientAuth {
+    None,
+    OAuth(McpOAuthConfig),
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct McpClientBootstrap {
+    pub server_name: String,
+    pub normalized_name: String,
+    pub tool_prefix: String,
+    pub signature: Option<String>,
+    pub transport: McpClientTransport,
+}
+
+impl McpClientBootstrap {
+    #[must_use]
+    pub fn from_scoped_config(server_name: &str, config: &ScopedMcpServerConfig) -> Self {
+        Self {
+            server_name: server_name.to_string(),
+            normalized_name: normalize_name_for_mcp(server_name),
+            tool_prefix: mcp_tool_prefix(server_name),
+            signature: mcp_server_signature(&config.config),
+            transport: McpClientTransport::from_config(&config.config),
+        }
+    }
+}
+
+impl McpClientTransport {
+    #[must_use]
+    pub fn from_config(config: &McpServerConfig) -> Self {
+        match config {
+            McpServerConfig::Stdio(config) => Self::Stdio(McpStdioTransport {
+                command: config.command.clone(),
+                args: config.args.clone(),
+                env: config.env.clone(),
+            }),
+            McpServerConfig::Sse(config) => Self::Sse(McpRemoteTransport {
+                url: config.url.clone(),
+                headers: config.headers.clone(),
+                headers_helper: config.headers_helper.clone(),
+                auth: McpClientAuth::from_oauth(config.oauth.clone()),
+            }),
+            McpServerConfig::Http(config) => Self::Http(McpRemoteTransport {
+                url: config.url.clone(),
+                headers: config.headers.clone(),
+                headers_helper: config.headers_helper.clone(),
+                auth: McpClientAuth::from_oauth(config.oauth.clone()),
+            }),
+            McpServerConfig::Ws(config) => Self::WebSocket(McpRemoteTransport {
+                url: config.url.clone(),
+                headers: config.headers.clone(),
+                headers_helper: config.headers_helper.clone(),
+                auth: McpClientAuth::None,
+            }),
+            McpServerConfig::Sdk(config) => Self::Sdk(McpSdkTransport {
+                name: config.name.clone(),
+            }),
+            McpServerConfig::ClaudeAiProxy(config) => {
+                Self::ClaudeAiProxy(McpClaudeAiProxyTransport {
+                    url: config.url.clone(),
+                    id: config.id.clone(),
+                })
+            }
+        }
+    }
+}
+
+impl McpClientAuth {
+    #[must_use]
+    pub fn from_oauth(oauth: Option<McpOAuthConfig>) -> Self {
+        oauth.map_or(Self::None, Self::OAuth)
+    }
+
+    #[must_use]
+    pub const fn requires_user_auth(&self) -> bool {
+        matches!(self, Self::OAuth(_))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::collections::BTreeMap;
+
+    use crate::config::{
+        ConfigSource, McpOAuthConfig, McpRemoteServerConfig, McpSdkServerConfig, McpServerConfig,
+        McpStdioServerConfig, McpWebSocketServerConfig, ScopedMcpServerConfig,
+    };
+
+    use super::{McpClientAuth, McpClientBootstrap, McpClientTransport};
+
+    #[test]
+    fn bootstraps_stdio_servers_into_transport_targets() {
+        let config = ScopedMcpServerConfig {
+            scope: ConfigSource::User,
+            config: McpServerConfig::Stdio(McpStdioServerConfig {
+                command: "uvx".to_string(),
+                args: vec!["mcp-server".to_string()],
+                env: BTreeMap::from([("TOKEN".to_string(), "secret".to_string())]),
+            }),
+        };
+
+        let bootstrap = McpClientBootstrap::from_scoped_config("stdio-server", &config);
+        assert_eq!(bootstrap.normalized_name, "stdio-server");
+        assert_eq!(bootstrap.tool_prefix, "mcp__stdio-server__");
+        assert_eq!(
+            bootstrap.signature.as_deref(),
+            Some("stdio:[uvx|mcp-server]")
+        );
+        match bootstrap.transport {
+            McpClientTransport::Stdio(transport) => {
+                assert_eq!(transport.command, "uvx");
+                assert_eq!(transport.args, vec!["mcp-server"]);
+                assert_eq!(
+                    transport.env.get("TOKEN").map(String::as_str),
+                    Some("secret")
+                );
+            }
+            other => panic!("expected stdio transport, got {other:?}"),
+        }
+    }
+
+    #[test]
+    fn bootstraps_remote_servers_with_oauth_auth() {
+        let config = ScopedMcpServerConfig {
+            scope: ConfigSource::Project,
+            config: McpServerConfig::Http(McpRemoteServerConfig {
+                url: "https://vendor.example/mcp".to_string(),
+                headers: BTreeMap::from([("X-Test".to_string(), "1".to_string())]),
+                headers_helper: Some("helper.sh".to_string()),
+                oauth: Some(McpOAuthConfig {
+                    client_id: Some("client-id".to_string()),
+                    callback_port: Some(7777),
+                    auth_server_metadata_url: Some(
+                        "https://issuer.example/.well-known/oauth-authorization-server".to_string(),
+                    ),
+                    xaa: Some(true),
+                }),
+            }),
+        };
+
+        let bootstrap = McpClientBootstrap::from_scoped_config("remote server", &config);
+        assert_eq!(bootstrap.normalized_name, "remote_server");
+        match bootstrap.transport {
+            McpClientTransport::Http(transport) => {
+                assert_eq!(transport.url, "https://vendor.example/mcp");
+                assert_eq!(transport.headers_helper.as_deref(), Some("helper.sh"));
+                assert!(transport.auth.requires_user_auth());
+                match transport.auth {
+                    McpClientAuth::OAuth(oauth) => {
+                        assert_eq!(oauth.client_id.as_deref(), Some("client-id"));
+                    }
+                    other @ McpClientAuth::None => panic!("expected oauth auth, got {other:?}"),
+                }
+            }
+            other => panic!("expected http transport, got {other:?}"),
+        }
+    }
+
+    #[test]
+    fn bootstraps_websocket_and_sdk_transports_without_oauth() {
+        let ws = ScopedMcpServerConfig {
+            scope: ConfigSource::Local,
+            config: McpServerConfig::Ws(McpWebSocketServerConfig {
+                url: "wss://vendor.example/mcp".to_string(),
+                headers: BTreeMap::new(),
+                headers_helper: None,
+            }),
+        };
+        let sdk = ScopedMcpServerConfig {
+            scope: ConfigSource::Local,
+            config: McpServerConfig::Sdk(McpSdkServerConfig {
+                name: "sdk-server".to_string(),
+            }),
+        };
+
+        let ws_bootstrap = McpClientBootstrap::from_scoped_config("ws server", &ws);
+        match ws_bootstrap.transport {
+            McpClientTransport::WebSocket(transport) => {
+                assert_eq!(transport.url, "wss://vendor.example/mcp");
+                assert!(!transport.auth.requires_user_auth());
+            }
+            other => panic!("expected websocket transport, got {other:?}"),
+        }
+
+        let sdk_bootstrap = McpClientBootstrap::from_scoped_config("sdk server", &sdk);
+        assert_eq!(sdk_bootstrap.signature, None);
+        match sdk_bootstrap.transport {
+            McpClientTransport::Sdk(transport) => {
+                assert_eq!(transport.name, "sdk-server");
+            }
+            other => panic!("expected sdk transport, got {other:?}"),
+        }
+    }
+}

rust/crates/runtime/src/oauth.rs

@@ -0,0 +1,589 @@
+use std::collections::BTreeMap;
+use std::fs::{self, File};
+use std::io::{self, Read};
+use std::path::PathBuf;
+
+use serde::{Deserialize, Serialize};
+use serde_json::{Map, Value};
+use sha2::{Digest, Sha256};
+
+use crate::config::OAuthConfig;
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct OAuthTokenSet {
+    pub access_token: String,
+    pub refresh_token: Option<String>,
+    pub expires_at: Option<u64>,
+    pub scopes: Vec<String>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct PkceCodePair {
+    pub verifier: String,
+    pub challenge: String,
+    pub challenge_method: PkceChallengeMethod,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum PkceChallengeMethod {
+    S256,
+}
+
+impl PkceChallengeMethod {
+    #[must_use]
+    pub const fn as_str(self) -> &'static str {
+        match self {
+            Self::S256 => "S256",
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct OAuthAuthorizationRequest {
+    pub authorize_url: String,
+    pub client_id: String,
+    pub redirect_uri: String,
+    pub scopes: Vec<String>,
+    pub state: String,
+    pub code_challenge: String,
+    pub code_challenge_method: PkceChallengeMethod,
+    pub extra_params: BTreeMap<String, String>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct OAuthTokenExchangeRequest {
+    pub grant_type: &'static str,
+    pub code: String,
+    pub redirect_uri: String,
+    pub client_id: String,
+    pub code_verifier: String,
+    pub state: String,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct OAuthRefreshRequest {
+    pub grant_type: &'static str,
+    pub refresh_token: String,
+    pub client_id: String,
+    pub scopes: Vec<String>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct OAuthCallbackParams {
+    pub code: Option<String>,
+    pub state: Option<String>,
+    pub error: Option<String>,
+    pub error_description: Option<String>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+struct StoredOAuthCredentials {
+    access_token: String,
+    #[serde(default)]
+    refresh_token: Option<String>,
+    #[serde(default)]
+    expires_at: Option<u64>,
+    #[serde(default)]
+    scopes: Vec<String>,
+}
+
+impl From<OAuthTokenSet> for StoredOAuthCredentials {
+    fn from(value: OAuthTokenSet) -> Self {
+        Self {
+            access_token: value.access_token,
+            refresh_token: value.refresh_token,
+            expires_at: value.expires_at,
+            scopes: value.scopes,
+        }
+    }
+}
+
+impl From<StoredOAuthCredentials> for OAuthTokenSet {
+    fn from(value: StoredOAuthCredentials) -> Self {
+        Self {
+            access_token: value.access_token,
+            refresh_token: value.refresh_token,
+            expires_at: value.expires_at,
+            scopes: value.scopes,
+        }
+    }
+}
+
+impl OAuthAuthorizationRequest {
+    #[must_use]
+    pub fn from_config(
+        config: &OAuthConfig,
+        redirect_uri: impl Into<String>,
+        state: impl Into<String>,
+        pkce: &PkceCodePair,
+    ) -> Self {
+        Self {
+            authorize_url: config.authorize_url.clone(),
+            client_id: config.client_id.clone(),
+            redirect_uri: redirect_uri.into(),
+            scopes: config.scopes.clone(),
+            state: state.into(),
+            code_challenge: pkce.challenge.clone(),
+            code_challenge_method: pkce.challenge_method,
+            extra_params: BTreeMap::new(),
+        }
+    }
+
+    #[must_use]
+    pub fn with_extra_param(mut self, key: impl Into<String>, value: impl Into<String>) -> Self {
+        self.extra_params.insert(key.into(), value.into());
+        self
+    }
+
+    #[must_use]
+    pub fn build_url(&self) -> String {
+        let mut params = vec![
+            ("response_type", "code".to_string()),
+            ("client_id", self.client_id.clone()),
+            ("redirect_uri", self.redirect_uri.clone()),
+            ("scope", self.scopes.join(" ")),
+            ("state", self.state.clone()),
+            ("code_challenge", self.code_challenge.clone()),
+            (
+                "code_challenge_method",
+                self.code_challenge_method.as_str().to_string(),
+            ),
+        ];
+        params.extend(
+            self.extra_params
+                .iter()
+                .map(|(key, value)| (key.as_str(), value.clone())),
+        );
+        let query = params
+            .into_iter()
+            .map(|(key, value)| format!("{}={}", percent_encode(key), percent_encode(&value)))
+            .collect::<Vec<_>>()
+            .join("&");
+        format!(
+            "{}{}{}",
+            self.authorize_url,
+            if self.authorize_url.contains('?') {
+                '&'
+            } else {
+                '?'
+            },
+            query
+        )
+    }
+}
+
+impl OAuthTokenExchangeRequest {
+    #[must_use]
+    pub fn from_config(
+        config: &OAuthConfig,
+        code: impl Into<String>,
+        state: impl Into<String>,
+        verifier: impl Into<String>,
+        redirect_uri: impl Into<String>,
+    ) -> Self {
+        Self {
+            grant_type: "authorization_code",
+            code: code.into(),
+            redirect_uri: redirect_uri.into(),
+            client_id: config.client_id.clone(),
+            code_verifier: verifier.into(),
+            state: state.into(),
+        }
+    }
+
+    #[must_use]
+    pub fn form_params(&self) -> BTreeMap<&str, String> {
+        BTreeMap::from([
+            ("grant_type", self.grant_type.to_string()),
+            ("code", self.code.clone()),
+            ("redirect_uri", self.redirect_uri.clone()),
+            ("client_id", self.client_id.clone()),
+            ("code_verifier", self.code_verifier.clone()),
+            ("state", self.state.clone()),
+        ])
+    }
+}
+
+impl OAuthRefreshRequest {
+    #[must_use]
+    pub fn from_config(
+        config: &OAuthConfig,
+        refresh_token: impl Into<String>,
+        scopes: Option<Vec<String>>,
+    ) -> Self {
+        Self {
+            grant_type: "refresh_token",
+            refresh_token: refresh_token.into(),
+            client_id: config.client_id.clone(),
+            scopes: scopes.unwrap_or_else(|| config.scopes.clone()),
+        }
+    }
+
+    #[must_use]
+    pub fn form_params(&self) -> BTreeMap<&str, String> {
+        BTreeMap::from([
+            ("grant_type", self.grant_type.to_string()),
+            ("refresh_token", self.refresh_token.clone()),
+            ("client_id", self.client_id.clone()),
+            ("scope", self.scopes.join(" ")),
+        ])
+    }
+}
+
+pub fn generate_pkce_pair() -> io::Result<PkceCodePair> {
+    let verifier = generate_random_token(32)?;
+    Ok(PkceCodePair {
+        challenge: code_challenge_s256(&verifier),
+        verifier,
+        challenge_method: PkceChallengeMethod::S256,
+    })
+}
+
+pub fn generate_state() -> io::Result<String> {
+    generate_random_token(32)
+}
+
+#[must_use]
+pub fn code_challenge_s256(verifier: &str) -> String {
+    let digest = Sha256::digest(verifier.as_bytes());
+    base64url_encode(&digest)
+}
+
+#[must_use]
+pub fn loopback_redirect_uri(port: u16) -> String {
+    format!("http://localhost:{port}/callback")
+}
+
+pub fn credentials_path() -> io::Result<PathBuf> {
+    Ok(credentials_home_dir()?.join("credentials.json"))
+}
+
+pub fn load_oauth_credentials() -> io::Result<Option<OAuthTokenSet>> {
+    let path = credentials_path()?;
+    let root = read_credentials_root(&path)?;
+    let Some(oauth) = root.get("oauth") else {
+        return Ok(None);
+    };
+    if oauth.is_null() {
+        return Ok(None);
+    }
+    let stored = serde_json::from_value::<StoredOAuthCredentials>(oauth.clone())
+        .map_err(|error| io::Error::new(io::ErrorKind::InvalidData, error))?;
+    Ok(Some(stored.into()))
+}
+
+pub fn save_oauth_credentials(token_set: &OAuthTokenSet) -> io::Result<()> {
+    let path = credentials_path()?;
+    let mut root = read_credentials_root(&path)?;
+    root.insert(
+        "oauth".to_string(),
+        serde_json::to_value(StoredOAuthCredentials::from(token_set.clone()))
+            .map_err(|error| io::Error::new(io::ErrorKind::InvalidData, error))?,
+    );
+    write_credentials_root(&path, &root)
+}
+
+pub fn clear_oauth_credentials() -> io::Result<()> {
+    let path = credentials_path()?;
+    let mut root = read_credentials_root(&path)?;
+    root.remove("oauth");
+    write_credentials_root(&path, &root)
+}
+
+pub fn parse_oauth_callback_request_target(target: &str) -> Result<OAuthCallbackParams, String> {
+    let (path, query) = target
+        .split_once('?')
+        .map_or((target, ""), |(path, query)| (path, query));
+    if path != "/callback" {
+        return Err(format!("unexpected callback path: {path}"));
+    }
+    parse_oauth_callback_query(query)
+}
+
+pub fn parse_oauth_callback_query(query: &str) -> Result<OAuthCallbackParams, String> {
+    let mut params = BTreeMap::new();
+    for pair in query.split('&').filter(|pair| !pair.is_empty()) {
+        let (key, value) = pair
+            .split_once('=')
+            .map_or((pair, ""), |(key, value)| (key, value));
+        params.insert(percent_decode(key)?, percent_decode(value)?);
+    }
+    Ok(OAuthCallbackParams {
+        code: params.get("code").cloned(),
+        state: params.get("state").cloned(),
+        error: params.get("error").cloned(),
+        error_description: params.get("error_description").cloned(),
+    })
+}
+
+fn generate_random_token(bytes: usize) -> io::Result<String> {
+    let mut buffer = vec![0_u8; bytes];
+    File::open("/dev/urandom")?.read_exact(&mut buffer)?;
+    Ok(base64url_encode(&buffer))
+}
+
+fn credentials_home_dir() -> io::Result<PathBuf> {
+    if let Some(path) = std::env::var_os("CLAUDE_CONFIG_HOME") {
+        return Ok(PathBuf::from(path));
+    }
+    let home = std::env::var_os("HOME")
+        .ok_or_else(|| io::Error::new(io::ErrorKind::NotFound, "HOME is not set"))?;
+    Ok(PathBuf::from(home).join(".claude"))
+}
+
+fn read_credentials_root(path: &PathBuf) -> io::Result<Map<String, Value>> {
+    match fs::read_to_string(path) {
+        Ok(contents) => {
+            if contents.trim().is_empty() {
+                return Ok(Map::new());
+            }
+            serde_json::from_str::<Value>(&contents)
+                .map_err(|error| io::Error::new(io::ErrorKind::InvalidData, error))?
+                .as_object()
+                .cloned()
+                .ok_or_else(|| {
+                    io::Error::new(
+                        io::ErrorKind::InvalidData,
+                        "credentials file must contain a JSON object",
+                    )
+                })
+        }
+        Err(error) if error.kind() == io::ErrorKind::NotFound => Ok(Map::new()),
+        Err(error) => Err(error),
+    }
+}
+
+fn write_credentials_root(path: &PathBuf, root: &Map<String, Value>) -> io::Result<()> {
+    if let Some(parent) = path.parent() {
+        fs::create_dir_all(parent)?;
+    }
+    let rendered = serde_json::to_string_pretty(&Value::Object(root.clone()))
+        .map_err(|error| io::Error::new(io::ErrorKind::InvalidData, error))?;
+    let temp_path = path.with_extension("json.tmp");
+    fs::write(&temp_path, format!("{rendered}\n"))?;
+    fs::rename(temp_path, path)
+}
+
+fn base64url_encode(bytes: &[u8]) -> String {
+    const TABLE: &[u8; 64] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
+    let mut output = String::new();
+    let mut index = 0;
+    while index + 3 <= bytes.len() {
+        let block = (u32::from(bytes[index]) << 16)
+            | (u32::from(bytes[index + 1]) << 8)
+            | u32::from(bytes[index + 2]);
+        output.push(TABLE[((block >> 18) & 0x3F) as usize] as char);
+        output.push(TABLE[((block >> 12) & 0x3F) as usize] as char);
+        output.push(TABLE[((block >> 6) & 0x3F) as usize] as char);
+        output.push(TABLE[(block & 0x3F) as usize] as char);
+        index += 3;
+    }
+    match bytes.len().saturating_sub(index) {
+        1 => {
+            let block = u32::from(bytes[index]) << 16;
+            output.push(TABLE[((block >> 18) & 0x3F) as usize] as char);
+            output.push(TABLE[((block >> 12) & 0x3F) as usize] as char);
+        }
+        2 => {
+            let block = (u32::from(bytes[index]) << 16) | (u32::from(bytes[index + 1]) << 8);
+            output.push(TABLE[((block >> 18) & 0x3F) as usize] as char);
+            output.push(TABLE[((block >> 12) & 0x3F) as usize] as char);
+            output.push(TABLE[((block >> 6) & 0x3F) as usize] as char);
+        }
+        _ => {}
+    }
+    output
+}
+
+fn percent_encode(value: &str) -> String {
+    let mut encoded = String::new();
+    for byte in value.bytes() {
+        match byte {
+            b'A'..=b'Z' | b'a'..=b'z' | b'0'..=b'9' | b'-' | b'_' | b'.' | b'~' => {
+                encoded.push(char::from(byte));
+            }
+            _ => {
+                use std::fmt::Write as _;
+                let _ = write!(&mut encoded, "%{byte:02X}");
+            }
+        }
+    }
+    encoded
+}
+
+fn percent_decode(value: &str) -> Result<String, String> {
+    let mut decoded = Vec::with_capacity(value.len());
+    let bytes = value.as_bytes();
+    let mut index = 0;
+    while index < bytes.len() {
+        match bytes[index] {
+            b'%' if index + 2 < bytes.len() => {
+                let hi = decode_hex(bytes[index + 1])?;
+                let lo = decode_hex(bytes[index + 2])?;
+                decoded.push((hi << 4) | lo);
+                index += 3;
+            }
+            b'+' => {
+                decoded.push(b' ');
+                index += 1;
+            }
+            byte => {
+                decoded.push(byte);
+                index += 1;
+            }
+        }
+    }
+    String::from_utf8(decoded).map_err(|error| error.to_string())
+}
+
+fn decode_hex(byte: u8) -> Result<u8, String> {
+    match byte {
+        b'0'..=b'9' => Ok(byte - b'0'),
+        b'a'..=b'f' => Ok(byte - b'a' + 10),
+        b'A'..=b'F' => Ok(byte - b'A' + 10),
+        _ => Err(format!("invalid percent-encoding byte: {byte}")),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::time::{SystemTime, UNIX_EPOCH};
+
+    use super::{
+        clear_oauth_credentials, code_challenge_s256, credentials_path, generate_pkce_pair,
+        generate_state, load_oauth_credentials, loopback_redirect_uri, parse_oauth_callback_query,
+        parse_oauth_callback_request_target, save_oauth_credentials, OAuthAuthorizationRequest,
+        OAuthConfig, OAuthRefreshRequest, OAuthTokenExchangeRequest, OAuthTokenSet,
+    };
+
+    fn sample_config() -> OAuthConfig {
+        OAuthConfig {
+            client_id: "runtime-client".to_string(),
+            authorize_url: "https://console.test/oauth/authorize".to_string(),
+            token_url: "https://console.test/oauth/token".to_string(),
+            callback_port: Some(4545),
+            manual_redirect_url: Some("https://console.test/oauth/callback".to_string()),
+            scopes: vec!["org:read".to_string(), "user:write".to_string()],
+        }
+    }
+
+    fn env_lock() -> std::sync::MutexGuard<'static, ()> {
+        crate::test_env_lock()
+    }
+
+    fn temp_config_home() -> std::path::PathBuf {
+        std::env::temp_dir().join(format!(
+            "runtime-oauth-test-{}-{}",
+            std::process::id(),
+            SystemTime::now()
+                .duration_since(UNIX_EPOCH)
+                .expect("time")
+                .as_nanos()
+        ))
+    }
+
+    #[test]
+    fn s256_challenge_matches_expected_vector() {
+        assert_eq!(
+            code_challenge_s256("dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk"),
+            "E9Melhoa2OwvFrEMTJguCHaoeK1t8URWbuGJSstw-cM"
+        );
+    }
+
+    #[test]
+    fn generates_pkce_pair_and_state() {
+        let pair = generate_pkce_pair().expect("pkce pair");
+        let state = generate_state().expect("state");
+        assert!(!pair.verifier.is_empty());
+        assert!(!pair.challenge.is_empty());
+        assert!(!state.is_empty());
+    }
+
+    #[test]
+    fn builds_authorize_url_and_form_requests() {
+        let config = sample_config();
+        let pair = generate_pkce_pair().expect("pkce");
+        let url = OAuthAuthorizationRequest::from_config(
+            &config,
+            loopback_redirect_uri(4545),
+            "state-123",
+            &pair,
+        )
+        .with_extra_param("login_hint", "user@example.com")
+        .build_url();
+        assert!(url.starts_with("https://console.test/oauth/authorize?"));
+        assert!(url.contains("response_type=code"));
+        assert!(url.contains("client_id=runtime-client"));
+        assert!(url.contains("scope=org%3Aread%20user%3Awrite"));
+        assert!(url.contains("login_hint=user%40example.com"));
+
+        let exchange = OAuthTokenExchangeRequest::from_config(
+            &config,
+            "auth-code",
+            "state-123",
+            pair.verifier,
+            loopback_redirect_uri(4545),
+        );
+        assert_eq!(
+            exchange.form_params().get("grant_type").map(String::as_str),
+            Some("authorization_code")
+        );
+
+        let refresh = OAuthRefreshRequest::from_config(&config, "refresh-token", None);
+        assert_eq!(
+            refresh.form_params().get("scope").map(String::as_str),
+            Some("org:read user:write")
+        );
+    }
+
+    #[test]
+    fn oauth_credentials_round_trip_and_clear_preserves_other_fields() {
+        let _guard = env_lock();
+        let config_home = temp_config_home();
+        std::env::set_var("CLAUDE_CONFIG_HOME", &config_home);
+        let path = credentials_path().expect("credentials path");
+        std::fs::create_dir_all(path.parent().expect("parent")).expect("create parent");
+        std::fs::write(&path, "{\"other\":\"value\"}\n").expect("seed credentials");
+
+        let token_set = OAuthTokenSet {
+            access_token: "access-token".to_string(),
+            refresh_token: Some("refresh-token".to_string()),
+            expires_at: Some(123),
+            scopes: vec!["scope:a".to_string()],
+        };
+        save_oauth_credentials(&token_set).expect("save credentials");
+        assert_eq!(
+            load_oauth_credentials().expect("load credentials"),
+            Some(token_set)
+        );
+        let saved = std::fs::read_to_string(&path).expect("read saved file");
+        assert!(saved.contains("\"other\": \"value\""));
+        assert!(saved.contains("\"oauth\""));
+
+        clear_oauth_credentials().expect("clear credentials");
+        assert_eq!(load_oauth_credentials().expect("load cleared"), None);
+        let cleared = std::fs::read_to_string(&path).expect("read cleared file");
+        assert!(cleared.contains("\"other\": \"value\""));
+        assert!(!cleared.contains("\"oauth\""));
+
+        std::env::remove_var("CLAUDE_CONFIG_HOME");
+        std::fs::remove_dir_all(config_home).expect("cleanup temp dir");
+    }
+
+    #[test]
+    fn parses_callback_query_and_target() {
+        let params =
+            parse_oauth_callback_query("code=abc123&state=state-1&error_description=needs%20login")
+                .expect("parse query");
+        assert_eq!(params.code.as_deref(), Some("abc123"));
+        assert_eq!(params.state.as_deref(), Some("state-1"));
+        assert_eq!(params.error_description.as_deref(), Some("needs login"));
+
+        let params = parse_oauth_callback_request_target("/callback?code=abc&state=xyz")
+            .expect("parse callback target");
+        assert_eq!(params.code.as_deref(), Some("abc"));
+        assert_eq!(params.state.as_deref(), Some("xyz"));
+        assert!(parse_oauth_callback_request_target("/wrong?code=abc").is_err());
+    }
+}

rust/crates/runtime/src/permissions.rs

@@ -1,16 +1,29 @@
 use std::collections::BTreeMap;
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
 pub enum PermissionMode {
-    Allow,
+    ReadOnly,
-    Deny,
+    WorkspaceWrite,
-    Prompt,
+    DangerFullAccess,
+}
+
+impl PermissionMode {
+    #[must_use]
+    pub fn as_str(self) -> &'static str {
+        match self {
+            Self::ReadOnly => "read-only",
+            Self::WorkspaceWrite => "workspace-write",
+            Self::DangerFullAccess => "danger-full-access",
+        }
+    }
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct PermissionRequest {
     pub tool_name: String,
     pub input: String,
+    pub current_mode: PermissionMode,
+    pub required_mode: PermissionMode,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -31,31 +44,41 @@ pub enum PermissionOutcome {
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct PermissionPolicy {
-    default_mode: PermissionMode,
+    active_mode: PermissionMode,
-    tool_modes: BTreeMap<String, PermissionMode>,
+    tool_requirements: BTreeMap<String, PermissionMode>,
 }
 
 impl PermissionPolicy {
     #[must_use]
-    pub fn new(default_mode: PermissionMode) -> Self {
+    pub fn new(active_mode: PermissionMode) -> Self {
         Self {
-            default_mode,
+            active_mode,
-            tool_modes: BTreeMap::new(),
+            tool_requirements: BTreeMap::new(),
         }
     }
 
     #[must_use]
-    pub fn with_tool_mode(mut self, tool_name: impl Into<String>, mode: PermissionMode) -> Self {
+    pub fn with_tool_requirement(
-        self.tool_modes.insert(tool_name.into(), mode);
+        mut self,
+        tool_name: impl Into<String>,
+        required_mode: PermissionMode,
+    ) -> Self {
+        self.tool_requirements
+            .insert(tool_name.into(), required_mode);
         self
     }
 
     #[must_use]
-    pub fn mode_for(&self, tool_name: &str) -> PermissionMode {
+    pub fn active_mode(&self) -> PermissionMode {
-        self.tool_modes
+        self.active_mode
+    }
+
+    #[must_use]
+    pub fn required_mode_for(&self, tool_name: &str) -> PermissionMode {
+        self.tool_requirements
             .get(tool_name)
             .copied()
-            .unwrap_or(self.default_mode)
+            .unwrap_or(PermissionMode::DangerFullAccess)
     }
 
     #[must_use]
@@ -65,23 +88,43 @@ impl PermissionPolicy {
         input: &str,
         mut prompter: Option<&mut dyn PermissionPrompter>,
     ) -> PermissionOutcome {
-        match self.mode_for(tool_name) {
+        let current_mode = self.active_mode();
-            PermissionMode::Allow => PermissionOutcome::Allow,
+        let required_mode = self.required_mode_for(tool_name);
-            PermissionMode::Deny => PermissionOutcome::Deny {
+        if current_mode >= required_mode {
-                reason: format!("tool '{tool_name}' denied by permission policy"),
+            return PermissionOutcome::Allow;
-            },
+        }
-            PermissionMode::Prompt => match prompter.as_mut() {
+
-                Some(prompter) => match prompter.decide(&PermissionRequest {
+        let request = PermissionRequest {
-                    tool_name: tool_name.to_string(),
+            tool_name: tool_name.to_string(),
-                    input: input.to_string(),
+            input: input.to_string(),
-                }) {
+            current_mode,
+            required_mode,
+        };
+
+        if current_mode == PermissionMode::WorkspaceWrite
+            && required_mode == PermissionMode::DangerFullAccess
+        {
+            return match prompter.as_mut() {
+                Some(prompter) => match prompter.decide(&request) {
                     PermissionPromptDecision::Allow => PermissionOutcome::Allow,
                     PermissionPromptDecision::Deny { reason } => PermissionOutcome::Deny { reason },
                 },
                 None => PermissionOutcome::Deny {
-                    reason: format!("tool '{tool_name}' requires interactive approval"),
+                    reason: format!(
+                        "tool '{tool_name}' requires approval to escalate from {} to {}",
+                        current_mode.as_str(),
+                        required_mode.as_str()
+                    ),
                 },
-            },
+            };
+        }
+
+        PermissionOutcome::Deny {
+            reason: format!(
+                "tool '{tool_name}' requires {} permission; current mode is {}",
+                required_mode.as_str(),
+                current_mode.as_str()
+            ),
         }
     }
 }
@@ -93,25 +136,92 @@ mod tests {
         PermissionPrompter, PermissionRequest,
     };
 
-    struct AllowPrompter;
+    struct RecordingPrompter {
+        seen: Vec<PermissionRequest>,
+        allow: bool,
+    }
 
-    impl PermissionPrompter for AllowPrompter {
+    impl PermissionPrompter for RecordingPrompter {
         fn decide(&mut self, request: &PermissionRequest) -> PermissionPromptDecision {
-            assert_eq!(request.tool_name, "bash");
+            self.seen.push(request.clone());
-            PermissionPromptDecision::Allow
+            if self.allow {
+                PermissionPromptDecision::Allow
+            } else {
+                PermissionPromptDecision::Deny {
+                    reason: "not now".to_string(),
+                }
+            }
         }
     }
 
     #[test]
-    fn uses_tool_specific_overrides() {
+    fn allows_tools_when_active_mode_meets_requirement() {
-        let policy = PermissionPolicy::new(PermissionMode::Deny)
+        let policy = PermissionPolicy::new(PermissionMode::WorkspaceWrite)
-            .with_tool_mode("bash", PermissionMode::Prompt);
+            .with_tool_requirement("read_file", PermissionMode::ReadOnly)
+            .with_tool_requirement("write_file", PermissionMode::WorkspaceWrite);
+
+        assert_eq!(
+            policy.authorize("read_file", "{}", None),
+            PermissionOutcome::Allow
+        );
+        assert_eq!(
+            policy.authorize("write_file", "{}", None),
+            PermissionOutcome::Allow
+        );
+    }
+
+    #[test]
+    fn denies_read_only_escalations_without_prompt() {
+        let policy = PermissionPolicy::new(PermissionMode::ReadOnly)
+            .with_tool_requirement("write_file", PermissionMode::WorkspaceWrite)
+            .with_tool_requirement("bash", PermissionMode::DangerFullAccess);
 
-        let outcome = policy.authorize("bash", "echo hi", Some(&mut AllowPrompter));
-        assert_eq!(outcome, PermissionOutcome::Allow);
         assert!(matches!(
-            policy.authorize("edit", "x", None),
+            policy.authorize("write_file", "{}", None),
-            PermissionOutcome::Deny { .. }
+            PermissionOutcome::Deny { reason } if reason.contains("requires workspace-write permission")
+        ));
+        assert!(matches!(
+            policy.authorize("bash", "{}", None),
+            PermissionOutcome::Deny { reason } if reason.contains("requires danger-full-access permission")
+        ));
+    }
+
+    #[test]
+    fn prompts_for_workspace_write_to_danger_full_access_escalation() {
+        let policy = PermissionPolicy::new(PermissionMode::WorkspaceWrite)
+            .with_tool_requirement("bash", PermissionMode::DangerFullAccess);
+        let mut prompter = RecordingPrompter {
+            seen: Vec::new(),
+            allow: true,
+        };
+
+        let outcome = policy.authorize("bash", "echo hi", Some(&mut prompter));
+
+        assert_eq!(outcome, PermissionOutcome::Allow);
+        assert_eq!(prompter.seen.len(), 1);
+        assert_eq!(prompter.seen[0].tool_name, "bash");
+        assert_eq!(
+            prompter.seen[0].current_mode,
+            PermissionMode::WorkspaceWrite
+        );
+        assert_eq!(
+            prompter.seen[0].required_mode,
+            PermissionMode::DangerFullAccess
+        );
+    }
+
+    #[test]
+    fn honors_prompt_rejection_reason() {
+        let policy = PermissionPolicy::new(PermissionMode::WorkspaceWrite)
+            .with_tool_requirement("bash", PermissionMode::DangerFullAccess);
+        let mut prompter = RecordingPrompter {
+            seen: Vec::new(),
+            allow: false,
+        };
+
+        assert!(matches!(
+            policy.authorize("bash", "echo hi", Some(&mut prompter)),
+            PermissionOutcome::Deny { reason } if reason == "not now"
         ));
     }
 }

rust/crates/runtime/src/prompt.rs

@@ -1,4 +1,5 @@
 use std::fs;
+use std::hash::{Hash, Hasher};
 use std::path::{Path, PathBuf};
 use std::process::Command;
 
@@ -35,6 +36,8 @@ impl From<ConfigError> for PromptBuildError {
 
 pub const SYSTEM_PROMPT_DYNAMIC_BOUNDARY: &str = "__SYSTEM_PROMPT_DYNAMIC_BOUNDARY__";
 pub const FRONTIER_MODEL_NAME: &str = "Claude Opus 4.6";
+const MAX_INSTRUCTION_FILE_CHARS: usize = 4_000;
+const MAX_TOTAL_INSTRUCTION_CHARS: usize = 12_000;
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct ContextFile {
@@ -198,11 +201,12 @@ fn discover_instruction_files(cwd: &Path) -> std::io::Result<Vec<ContextFile>> {
             dir.join("CLAUDE.md"),
             dir.join("CLAUDE.local.md"),
             dir.join(".claude").join("CLAUDE.md"),
+            dir.join(".claude").join("instructions.md"),
         ] {
             push_context_file(&mut files, candidate)?;
         }
     }
-    Ok(files)
+    Ok(dedupe_instruction_files(files))
 }
 
 fn push_context_file(files: &mut Vec<ContextFile>, path: PathBuf) -> std::io::Result<()> {
@@ -237,10 +241,17 @@ fn read_git_status(cwd: &Path) -> Option<String> {
 
 fn render_project_context(project_context: &ProjectContext) -> String {
     let mut lines = vec!["# Project context".to_string()];
-    lines.extend(prepend_bullets(vec![format!(
+    let mut bullets = vec![
-        "Today's date is {}.",
+        format!("Today's date is {}.", project_context.current_date),
-        project_context.current_date
+        format!("Working directory: {}", project_context.cwd.display()),
-    )]));
+    ];
+    if !project_context.instruction_files.is_empty() {
+        bullets.push(format!(
+            "Claude instruction files discovered: {}.",
+            project_context.instruction_files.len()
+        ));
+    }
+    lines.extend(prepend_bullets(bullets));
     if let Some(status) = &project_context.git_status {
         lines.push(String::new());
         lines.push("Git status snapshot:".to_string());
@@ -251,13 +262,105 @@ fn render_project_context(project_context: &ProjectContext) -> String {
 
 fn render_instruction_files(files: &[ContextFile]) -> String {
     let mut sections = vec!["# Claude instructions".to_string()];
+    let mut remaining_chars = MAX_TOTAL_INSTRUCTION_CHARS;
     for file in files {
-        sections.push(format!("## {}", file.path.display()));
+        if remaining_chars == 0 {
-        sections.push(file.content.trim().to_string());
+            sections.push(
+                "_Additional instruction content omitted after reaching the prompt budget._"
+                    .to_string(),
+            );
+            break;
+        }
+
+        let raw_content = truncate_instruction_content(&file.content, remaining_chars);
+        let rendered_content = render_instruction_content(&raw_content);
+        let consumed = rendered_content.chars().count().min(remaining_chars);
+        remaining_chars = remaining_chars.saturating_sub(consumed);
+
+        sections.push(format!("## {}", describe_instruction_file(file, files)));
+        sections.push(rendered_content);
     }
     sections.join("\n\n")
 }
 
+fn dedupe_instruction_files(files: Vec<ContextFile>) -> Vec<ContextFile> {
+    let mut deduped = Vec::new();
+    let mut seen_hashes = Vec::new();
+
+    for file in files {
+        let normalized = normalize_instruction_content(&file.content);
+        let hash = stable_content_hash(&normalized);
+        if seen_hashes.contains(&hash) {
+            continue;
+        }
+        seen_hashes.push(hash);
+        deduped.push(file);
+    }
+
+    deduped
+}
+
+fn normalize_instruction_content(content: &str) -> String {
+    collapse_blank_lines(content).trim().to_string()
+}
+
+fn stable_content_hash(content: &str) -> u64 {
+    let mut hasher = std::collections::hash_map::DefaultHasher::new();
+    content.hash(&mut hasher);
+    hasher.finish()
+}
+
+fn describe_instruction_file(file: &ContextFile, files: &[ContextFile]) -> String {
+    let path = display_context_path(&file.path);
+    let scope = files
+        .iter()
+        .filter_map(|candidate| candidate.path.parent())
+        .find(|parent| file.path.starts_with(parent))
+        .map_or_else(
+            || "workspace".to_string(),
+            |parent| parent.display().to_string(),
+        );
+    format!("{path} (scope: {scope})")
+}
+
+fn truncate_instruction_content(content: &str, remaining_chars: usize) -> String {
+    let hard_limit = MAX_INSTRUCTION_FILE_CHARS.min(remaining_chars);
+    let trimmed = content.trim();
+    if trimmed.chars().count() <= hard_limit {
+        return trimmed.to_string();
+    }
+
+    let mut output = trimmed.chars().take(hard_limit).collect::<String>();
+    output.push_str("\n\n[truncated]");
+    output
+}
+
+fn render_instruction_content(content: &str) -> String {
+    truncate_instruction_content(content, MAX_INSTRUCTION_FILE_CHARS)
+}
+
+fn display_context_path(path: &Path) -> String {
+    path.file_name().map_or_else(
+        || path.display().to_string(),
+        |name| name.to_string_lossy().into_owned(),
+    )
+}
+
+fn collapse_blank_lines(content: &str) -> String {
+    let mut result = String::new();
+    let mut previous_blank = false;
+    for line in content.lines() {
+        let is_blank = line.trim().is_empty();
+        if is_blank && previous_blank {
+            continue;
+        }
+        result.push_str(line.trim_end());
+        result.push('\n');
+        previous_blank = is_blank;
+    }
+    result
+}
+
 pub fn load_system_prompt(
     cwd: impl Into<PathBuf>,
     current_date: impl Into<String>,
@@ -348,9 +451,14 @@ fn get_actions_section() -> String {
 
 #[cfg(test)]
 mod tests {
-    use super::{ProjectContext, SystemPromptBuilder, SYSTEM_PROMPT_DYNAMIC_BOUNDARY};
+    use super::{
+        collapse_blank_lines, display_context_path, normalize_instruction_content,
+        render_instruction_content, render_instruction_files, truncate_instruction_content,
+        ContextFile, ProjectContext, SystemPromptBuilder, SYSTEM_PROMPT_DYNAMIC_BOUNDARY,
+    };
     use crate::config::ConfigLoader;
     use std::fs;
+    use std::path::{Path, PathBuf};
     use std::time::{SystemTime, UNIX_EPOCH};
 
     fn temp_dir() -> std::path::PathBuf {
@@ -361,6 +469,10 @@ mod tests {
         std::env::temp_dir().join(format!("runtime-prompt-{nanos}"))
     }
 
+    fn env_lock() -> std::sync::MutexGuard<'static, ()> {
+        crate::test_env_lock()
+    }
+
     #[test]
     fn discovers_instruction_files_from_ancestor_chain() {
         let root = temp_dir();
@@ -370,10 +482,21 @@ mod tests {
         fs::write(root.join("CLAUDE.local.md"), "local instructions")
             .expect("write local instructions");
         fs::create_dir_all(root.join("apps")).expect("apps dir");
+        fs::create_dir_all(root.join("apps").join(".claude")).expect("apps claude dir");
         fs::write(root.join("apps").join("CLAUDE.md"), "apps instructions")
             .expect("write apps instructions");
+        fs::write(
+            root.join("apps").join(".claude").join("instructions.md"),
+            "apps dot claude instructions",
+        )
+        .expect("write apps dot claude instructions");
         fs::write(nested.join(".claude").join("CLAUDE.md"), "nested rules")
             .expect("write nested rules");
+        fs::write(
+            nested.join(".claude").join("instructions.md"),
+            "nested instructions",
+        )
+        .expect("write nested instructions");
 
         let context = ProjectContext::discover(&nested, "2026-03-31").expect("context should load");
         let contents = context
@@ -388,12 +511,53 @@ mod tests {
                 "root instructions",
                 "local instructions",
                 "apps instructions",
-                "nested rules"
+                "apps dot claude instructions",
+                "nested rules",
+                "nested instructions"
             ]
         );
         fs::remove_dir_all(root).expect("cleanup temp dir");
     }
 
+    #[test]
+    fn dedupes_identical_instruction_content_across_scopes() {
+        let root = temp_dir();
+        let nested = root.join("apps").join("api");
+        fs::create_dir_all(&nested).expect("nested dir");
+        fs::write(root.join("CLAUDE.md"), "same rules\n\n").expect("write root");
+        fs::write(nested.join("CLAUDE.md"), "same rules\n").expect("write nested");
+
+        let context = ProjectContext::discover(&nested, "2026-03-31").expect("context should load");
+        assert_eq!(context.instruction_files.len(), 1);
+        assert_eq!(
+            normalize_instruction_content(&context.instruction_files[0].content),
+            "same rules"
+        );
+        fs::remove_dir_all(root).expect("cleanup temp dir");
+    }
+
+    #[test]
+    fn truncates_large_instruction_content_for_rendering() {
+        let rendered = render_instruction_content(&"x".repeat(4500));
+        assert!(rendered.contains("[truncated]"));
+        assert!(rendered.len() < 4_100);
+    }
+
+    #[test]
+    fn normalizes_and_collapses_blank_lines() {
+        let normalized = normalize_instruction_content("line one\n\n\nline two\n");
+        assert_eq!(normalized, "line one\n\nline two");
+        assert_eq!(collapse_blank_lines("a\n\n\n\nb\n"), "a\n\nb\n");
+    }
+
+    #[test]
+    fn displays_context_paths_compactly() {
+        assert_eq!(
+            display_context_path(Path::new("/tmp/project/.claude/CLAUDE.md")),
+            "CLAUDE.md"
+        );
+    }
+
     #[test]
     fn discover_with_git_includes_status_snapshot() {
         let root = temp_dir();
@@ -428,7 +592,12 @@ mod tests {
         )
         .expect("write settings");
 
+        let _guard = env_lock();
         let previous = std::env::current_dir().expect("cwd");
+        let original_home = std::env::var("HOME").ok();
+        let original_claude_home = std::env::var("CLAUDE_CONFIG_HOME").ok();
+        std::env::set_var("HOME", &root);
+        std::env::set_var("CLAUDE_CONFIG_HOME", root.join("missing-home"));
         std::env::set_current_dir(&root).expect("change cwd");
         let prompt = super::load_system_prompt(&root, "2026-03-31", "linux", "6.8")
             .expect("system prompt should load")
@@ -438,6 +607,16 @@ mod tests {
 ",
             );
         std::env::set_current_dir(previous).expect("restore cwd");
+        if let Some(value) = original_home {
+            std::env::set_var("HOME", value);
+        } else {
+            std::env::remove_var("HOME");
+        }
+        if let Some(value) = original_claude_home {
+            std::env::set_var("CLAUDE_CONFIG_HOME", value);
+        } else {
+            std::env::remove_var("CLAUDE_CONFIG_HOME");
+        }
 
         assert!(prompt.contains("Project rules"));
         assert!(prompt.contains("permissionMode"));
@@ -476,4 +655,46 @@ mod tests {
 
         fs::remove_dir_all(root).expect("cleanup temp dir");
     }
+
+    #[test]
+    fn truncates_instruction_content_to_budget() {
+        let content = "x".repeat(5_000);
+        let rendered = truncate_instruction_content(&content, 4_000);
+        assert!(rendered.contains("[truncated]"));
+        assert!(rendered.chars().count() <= 4_000 + "\n\n[truncated]".chars().count());
+    }
+
+    #[test]
+    fn discovers_dot_claude_instructions_markdown() {
+        let root = temp_dir();
+        let nested = root.join("apps").join("api");
+        fs::create_dir_all(nested.join(".claude")).expect("nested claude dir");
+        fs::write(
+            nested.join(".claude").join("instructions.md"),
+            "instruction markdown",
+        )
+        .expect("write instructions.md");
+
+        let context = ProjectContext::discover(&nested, "2026-03-31").expect("context should load");
+        assert!(context
+            .instruction_files
+            .iter()
+            .any(|file| file.path.ends_with(".claude/instructions.md")));
+        assert!(
+            render_instruction_files(&context.instruction_files).contains("instruction markdown")
+        );
+
+        fs::remove_dir_all(root).expect("cleanup temp dir");
+    }
+
+    #[test]
+    fn renders_instruction_file_metadata() {
+        let rendered = render_instruction_files(&[ContextFile {
+            path: PathBuf::from("/tmp/project/CLAUDE.md"),
+            content: "Project rules".to_string(),
+        }]);
+        assert!(rendered.contains("# Claude instructions"));
+        assert!(rendered.contains("scope: /tmp/project"));
+        assert!(rendered.contains("Project rules"));
+    }
 }

rust/crates/runtime/src/remote.rs

@@ -0,0 +1,401 @@
+use std::collections::BTreeMap;
+use std::env;
+use std::fs;
+use std::io;
+use std::path::{Path, PathBuf};
+
+pub const DEFAULT_REMOTE_BASE_URL: &str = "https://api.anthropic.com";
+pub const DEFAULT_SESSION_TOKEN_PATH: &str = "/run/ccr/session_token";
+pub const DEFAULT_SYSTEM_CA_BUNDLE: &str = "/etc/ssl/certs/ca-certificates.crt";
+
+pub const UPSTREAM_PROXY_ENV_KEYS: [&str; 8] = [
+    "HTTPS_PROXY",
+    "https_proxy",
+    "NO_PROXY",
+    "no_proxy",
+    "SSL_CERT_FILE",
+    "NODE_EXTRA_CA_CERTS",
+    "REQUESTS_CA_BUNDLE",
+    "CURL_CA_BUNDLE",
+];
+
+pub const NO_PROXY_HOSTS: [&str; 16] = [
+    "localhost",
+    "127.0.0.1",
+    "::1",
+    "169.254.0.0/16",
+    "10.0.0.0/8",
+    "172.16.0.0/12",
+    "192.168.0.0/16",
+    "anthropic.com",
+    ".anthropic.com",
+    "*.anthropic.com",
+    "github.com",
+    "api.github.com",
+    "*.github.com",
+    "*.githubusercontent.com",
+    "registry.npmjs.org",
+    "index.crates.io",
+];
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct RemoteSessionContext {
+    pub enabled: bool,
+    pub session_id: Option<String>,
+    pub base_url: String,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct UpstreamProxyBootstrap {
+    pub remote: RemoteSessionContext,
+    pub upstream_proxy_enabled: bool,
+    pub token_path: PathBuf,
+    pub ca_bundle_path: PathBuf,
+    pub system_ca_path: PathBuf,
+    pub token: Option<String>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct UpstreamProxyState {
+    pub enabled: bool,
+    pub proxy_url: Option<String>,
+    pub ca_bundle_path: Option<PathBuf>,
+    pub no_proxy: String,
+}
+
+impl RemoteSessionContext {
+    #[must_use]
+    pub fn from_env() -> Self {
+        Self::from_env_map(&env::vars().collect())
+    }
+
+    #[must_use]
+    pub fn from_env_map(env_map: &BTreeMap<String, String>) -> Self {
+        Self {
+            enabled: env_truthy(env_map.get("CLAUDE_CODE_REMOTE")),
+            session_id: env_map
+                .get("CLAUDE_CODE_REMOTE_SESSION_ID")
+                .filter(|value| !value.is_empty())
+                .cloned(),
+            base_url: env_map
+                .get("ANTHROPIC_BASE_URL")
+                .filter(|value| !value.is_empty())
+                .cloned()
+                .unwrap_or_else(|| DEFAULT_REMOTE_BASE_URL.to_string()),
+        }
+    }
+}
+
+impl UpstreamProxyBootstrap {
+    #[must_use]
+    pub fn from_env() -> Self {
+        Self::from_env_map(&env::vars().collect())
+    }
+
+    #[must_use]
+    pub fn from_env_map(env_map: &BTreeMap<String, String>) -> Self {
+        let remote = RemoteSessionContext::from_env_map(env_map);
+        let token_path = env_map
+            .get("CCR_SESSION_TOKEN_PATH")
+            .filter(|value| !value.is_empty())
+            .map_or_else(|| PathBuf::from(DEFAULT_SESSION_TOKEN_PATH), PathBuf::from);
+        let system_ca_path = env_map
+            .get("CCR_SYSTEM_CA_BUNDLE")
+            .filter(|value| !value.is_empty())
+            .map_or_else(|| PathBuf::from(DEFAULT_SYSTEM_CA_BUNDLE), PathBuf::from);
+        let ca_bundle_path = env_map
+            .get("CCR_CA_BUNDLE_PATH")
+            .filter(|value| !value.is_empty())
+            .map_or_else(default_ca_bundle_path, PathBuf::from);
+        let token = read_token(&token_path).ok().flatten();
+
+        Self {
+            remote,
+            upstream_proxy_enabled: env_truthy(env_map.get("CCR_UPSTREAM_PROXY_ENABLED")),
+            token_path,
+            ca_bundle_path,
+            system_ca_path,
+            token,
+        }
+    }
+
+    #[must_use]
+    pub fn should_enable(&self) -> bool {
+        self.remote.enabled
+            && self.upstream_proxy_enabled
+            && self.remote.session_id.is_some()
+            && self.token.is_some()
+    }
+
+    #[must_use]
+    pub fn ws_url(&self) -> String {
+        upstream_proxy_ws_url(&self.remote.base_url)
+    }
+
+    #[must_use]
+    pub fn state_for_port(&self, port: u16) -> UpstreamProxyState {
+        if !self.should_enable() {
+            return UpstreamProxyState::disabled();
+        }
+        UpstreamProxyState {
+            enabled: true,
+            proxy_url: Some(format!("http://127.0.0.1:{port}")),
+            ca_bundle_path: Some(self.ca_bundle_path.clone()),
+            no_proxy: no_proxy_list(),
+        }
+    }
+}
+
+impl UpstreamProxyState {
+    #[must_use]
+    pub fn disabled() -> Self {
+        Self {
+            enabled: false,
+            proxy_url: None,
+            ca_bundle_path: None,
+            no_proxy: no_proxy_list(),
+        }
+    }
+
+    #[must_use]
+    pub fn subprocess_env(&self) -> BTreeMap<String, String> {
+        if !self.enabled {
+            return BTreeMap::new();
+        }
+        let Some(proxy_url) = &self.proxy_url else {
+            return BTreeMap::new();
+        };
+        let Some(ca_bundle_path) = &self.ca_bundle_path else {
+            return BTreeMap::new();
+        };
+        let ca_bundle_path = ca_bundle_path.to_string_lossy().into_owned();
+        BTreeMap::from([
+            ("HTTPS_PROXY".to_string(), proxy_url.clone()),
+            ("https_proxy".to_string(), proxy_url.clone()),
+            ("NO_PROXY".to_string(), self.no_proxy.clone()),
+            ("no_proxy".to_string(), self.no_proxy.clone()),
+            ("SSL_CERT_FILE".to_string(), ca_bundle_path.clone()),
+            ("NODE_EXTRA_CA_CERTS".to_string(), ca_bundle_path.clone()),
+            ("REQUESTS_CA_BUNDLE".to_string(), ca_bundle_path.clone()),
+            ("CURL_CA_BUNDLE".to_string(), ca_bundle_path),
+        ])
+    }
+}
+
+pub fn read_token(path: &Path) -> io::Result<Option<String>> {
+    match fs::read_to_string(path) {
+        Ok(contents) => {
+            let token = contents.trim();
+            if token.is_empty() {
+                Ok(None)
+            } else {
+                Ok(Some(token.to_string()))
+            }
+        }
+        Err(error) if error.kind() == io::ErrorKind::NotFound => Ok(None),
+        Err(error) => Err(error),
+    }
+}
+
+#[must_use]
+pub fn upstream_proxy_ws_url(base_url: &str) -> String {
+    let base = base_url.trim_end_matches('/');
+    let ws_base = if let Some(stripped) = base.strip_prefix("https://") {
+        format!("wss://{stripped}")
+    } else if let Some(stripped) = base.strip_prefix("http://") {
+        format!("ws://{stripped}")
+    } else {
+        format!("wss://{base}")
+    };
+    format!("{ws_base}/v1/code/upstreamproxy/ws")
+}
+
+#[must_use]
+pub fn no_proxy_list() -> String {
+    let mut hosts = NO_PROXY_HOSTS.to_vec();
+    hosts.extend(["pypi.org", "files.pythonhosted.org", "proxy.golang.org"]);
+    hosts.join(",")
+}
+
+#[must_use]
+pub fn inherited_upstream_proxy_env(
+    env_map: &BTreeMap<String, String>,
+) -> BTreeMap<String, String> {
+    if !(env_map.contains_key("HTTPS_PROXY") && env_map.contains_key("SSL_CERT_FILE")) {
+        return BTreeMap::new();
+    }
+    UPSTREAM_PROXY_ENV_KEYS
+        .iter()
+        .filter_map(|key| {
+            env_map
+                .get(*key)
+                .map(|value| ((*key).to_string(), value.clone()))
+        })
+        .collect()
+}
+
+fn default_ca_bundle_path() -> PathBuf {
+    env::var_os("HOME")
+        .map_or_else(|| PathBuf::from("."), PathBuf::from)
+        .join(".ccr")
+        .join("ca-bundle.crt")
+}
+
+fn env_truthy(value: Option<&String>) -> bool {
+    value.is_some_and(|raw| {
+        matches!(
+            raw.trim().to_ascii_lowercase().as_str(),
+            "1" | "true" | "yes" | "on"
+        )
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{
+        inherited_upstream_proxy_env, no_proxy_list, read_token, upstream_proxy_ws_url,
+        RemoteSessionContext, UpstreamProxyBootstrap,
+    };
+    use std::collections::BTreeMap;
+    use std::fs;
+    use std::path::PathBuf;
+    use std::time::{SystemTime, UNIX_EPOCH};
+
+    fn temp_dir() -> PathBuf {
+        let nanos = SystemTime::now()
+            .duration_since(UNIX_EPOCH)
+            .expect("time should be after epoch")
+            .as_nanos();
+        std::env::temp_dir().join(format!("runtime-remote-{nanos}"))
+    }
+
+    #[test]
+    fn remote_context_reads_env_state() {
+        let env = BTreeMap::from([
+            ("CLAUDE_CODE_REMOTE".to_string(), "true".to_string()),
+            (
+                "CLAUDE_CODE_REMOTE_SESSION_ID".to_string(),
+                "session-123".to_string(),
+            ),
+            (
+                "ANTHROPIC_BASE_URL".to_string(),
+                "https://remote.test".to_string(),
+            ),
+        ]);
+        let context = RemoteSessionContext::from_env_map(&env);
+        assert!(context.enabled);
+        assert_eq!(context.session_id.as_deref(), Some("session-123"));
+        assert_eq!(context.base_url, "https://remote.test");
+    }
+
+    #[test]
+    fn bootstrap_fails_open_when_token_or_session_is_missing() {
+        let env = BTreeMap::from([
+            ("CLAUDE_CODE_REMOTE".to_string(), "1".to_string()),
+            ("CCR_UPSTREAM_PROXY_ENABLED".to_string(), "true".to_string()),
+        ]);
+        let bootstrap = UpstreamProxyBootstrap::from_env_map(&env);
+        assert!(!bootstrap.should_enable());
+        assert!(!bootstrap.state_for_port(8080).enabled);
+    }
+
+    #[test]
+    fn bootstrap_derives_proxy_state_and_env() {
+        let root = temp_dir();
+        let token_path = root.join("session_token");
+        fs::create_dir_all(&root).expect("temp dir");
+        fs::write(&token_path, "secret-token\n").expect("write token");
+
+        let env = BTreeMap::from([
+            ("CLAUDE_CODE_REMOTE".to_string(), "1".to_string()),
+            ("CCR_UPSTREAM_PROXY_ENABLED".to_string(), "true".to_string()),
+            (
+                "CLAUDE_CODE_REMOTE_SESSION_ID".to_string(),
+                "session-123".to_string(),
+            ),
+            (
+                "ANTHROPIC_BASE_URL".to_string(),
+                "https://remote.test".to_string(),
+            ),
+            (
+                "CCR_SESSION_TOKEN_PATH".to_string(),
+                token_path.to_string_lossy().into_owned(),
+            ),
+            (
+                "CCR_CA_BUNDLE_PATH".to_string(),
+                root.join("ca-bundle.crt").to_string_lossy().into_owned(),
+            ),
+        ]);
+
+        let bootstrap = UpstreamProxyBootstrap::from_env_map(&env);
+        assert!(bootstrap.should_enable());
+        assert_eq!(bootstrap.token.as_deref(), Some("secret-token"));
+        assert_eq!(
+            bootstrap.ws_url(),
+            "wss://remote.test/v1/code/upstreamproxy/ws"
+        );
+
+        let state = bootstrap.state_for_port(9443);
+        assert!(state.enabled);
+        let env = state.subprocess_env();
+        assert_eq!(
+            env.get("HTTPS_PROXY").map(String::as_str),
+            Some("http://127.0.0.1:9443")
+        );
+        assert_eq!(
+            env.get("SSL_CERT_FILE").map(String::as_str),
+            Some(root.join("ca-bundle.crt").to_string_lossy().as_ref())
+        );
+
+        fs::remove_dir_all(root).expect("cleanup temp dir");
+    }
+
+    #[test]
+    fn token_reader_trims_and_handles_missing_files() {
+        let root = temp_dir();
+        fs::create_dir_all(&root).expect("temp dir");
+        let token_path = root.join("session_token");
+        fs::write(&token_path, " abc123 \n").expect("write token");
+        assert_eq!(
+            read_token(&token_path).expect("read token").as_deref(),
+            Some("abc123")
+        );
+        assert_eq!(
+            read_token(&root.join("missing")).expect("missing token"),
+            None
+        );
+        fs::remove_dir_all(root).expect("cleanup temp dir");
+    }
+
+    #[test]
+    fn inherited_proxy_env_requires_proxy_and_ca() {
+        let env = BTreeMap::from([
+            (
+                "HTTPS_PROXY".to_string(),
+                "http://127.0.0.1:8888".to_string(),
+            ),
+            (
+                "SSL_CERT_FILE".to_string(),
+                "/tmp/ca-bundle.crt".to_string(),
+            ),
+            ("NO_PROXY".to_string(), "localhost".to_string()),
+        ]);
+        let inherited = inherited_upstream_proxy_env(&env);
+        assert_eq!(inherited.len(), 3);
+        assert_eq!(
+            inherited.get("NO_PROXY").map(String::as_str),
+            Some("localhost")
+        );
+        assert!(inherited_upstream_proxy_env(&BTreeMap::new()).is_empty());
+    }
+
+    #[test]
+    fn helper_outputs_match_expected_shapes() {
+        assert_eq!(
+            upstream_proxy_ws_url("http://localhost:3000/"),
+            "ws://localhost:3000/v1/code/upstreamproxy/ws"
+        );
+        assert!(no_proxy_list().contains("anthropic.com"));
+        assert!(no_proxy_list().contains("github.com"));
+    }
+}

rust/crates/runtime/src/usage.rs

@@ -1,5 +1,30 @@
 use crate::session::Session;
 
+const DEFAULT_INPUT_COST_PER_MILLION: f64 = 15.0;
+const DEFAULT_OUTPUT_COST_PER_MILLION: f64 = 75.0;
+const DEFAULT_CACHE_CREATION_COST_PER_MILLION: f64 = 18.75;
+const DEFAULT_CACHE_READ_COST_PER_MILLION: f64 = 1.5;
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub struct ModelPricing {
+    pub input_cost_per_million: f64,
+    pub output_cost_per_million: f64,
+    pub cache_creation_cost_per_million: f64,
+    pub cache_read_cost_per_million: f64,
+}
+
+impl ModelPricing {
+    #[must_use]
+    pub const fn default_sonnet_tier() -> Self {
+        Self {
+            input_cost_per_million: DEFAULT_INPUT_COST_PER_MILLION,
+            output_cost_per_million: DEFAULT_OUTPUT_COST_PER_MILLION,
+            cache_creation_cost_per_million: DEFAULT_CACHE_CREATION_COST_PER_MILLION,
+            cache_read_cost_per_million: DEFAULT_CACHE_READ_COST_PER_MILLION,
+        }
+    }
+}
+
 #[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
 pub struct TokenUsage {
     pub input_tokens: u32,
@@ -8,6 +33,49 @@ pub struct TokenUsage {
     pub cache_read_input_tokens: u32,
 }
 
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub struct UsageCostEstimate {
+    pub input_cost_usd: f64,
+    pub output_cost_usd: f64,
+    pub cache_creation_cost_usd: f64,
+    pub cache_read_cost_usd: f64,
+}
+
+impl UsageCostEstimate {
+    #[must_use]
+    pub fn total_cost_usd(self) -> f64 {
+        self.input_cost_usd
+            + self.output_cost_usd
+            + self.cache_creation_cost_usd
+            + self.cache_read_cost_usd
+    }
+}
+
+#[must_use]
+pub fn pricing_for_model(model: &str) -> Option<ModelPricing> {
+    let normalized = model.to_ascii_lowercase();
+    if normalized.contains("haiku") {
+        return Some(ModelPricing {
+            input_cost_per_million: 1.0,
+            output_cost_per_million: 5.0,
+            cache_creation_cost_per_million: 1.25,
+            cache_read_cost_per_million: 0.1,
+        });
+    }
+    if normalized.contains("opus") {
+        return Some(ModelPricing {
+            input_cost_per_million: 15.0,
+            output_cost_per_million: 75.0,
+            cache_creation_cost_per_million: 18.75,
+            cache_read_cost_per_million: 1.5,
+        });
+    }
+    if normalized.contains("sonnet") {
+        return Some(ModelPricing::default_sonnet_tier());
+    }
+    None
+}
+
 impl TokenUsage {
     #[must_use]
     pub fn total_tokens(self) -> u32 {
@@ -16,6 +84,79 @@ impl TokenUsage {
             + self.cache_creation_input_tokens
             + self.cache_read_input_tokens
     }
+
+    #[must_use]
+    pub fn estimate_cost_usd(self) -> UsageCostEstimate {
+        self.estimate_cost_usd_with_pricing(ModelPricing::default_sonnet_tier())
+    }
+
+    #[must_use]
+    pub fn estimate_cost_usd_with_pricing(self, pricing: ModelPricing) -> UsageCostEstimate {
+        UsageCostEstimate {
+            input_cost_usd: cost_for_tokens(self.input_tokens, pricing.input_cost_per_million),
+            output_cost_usd: cost_for_tokens(self.output_tokens, pricing.output_cost_per_million),
+            cache_creation_cost_usd: cost_for_tokens(
+                self.cache_creation_input_tokens,
+                pricing.cache_creation_cost_per_million,
+            ),
+            cache_read_cost_usd: cost_for_tokens(
+                self.cache_read_input_tokens,
+                pricing.cache_read_cost_per_million,
+            ),
+        }
+    }
+
+    #[must_use]
+    pub fn summary_lines(self, label: &str) -> Vec<String> {
+        self.summary_lines_for_model(label, None)
+    }
+
+    #[must_use]
+    pub fn summary_lines_for_model(self, label: &str, model: Option<&str>) -> Vec<String> {
+        let pricing = model.and_then(pricing_for_model);
+        let cost = pricing.map_or_else(
+            || self.estimate_cost_usd(),
+            |pricing| self.estimate_cost_usd_with_pricing(pricing),
+        );
+        let model_suffix =
+            model.map_or_else(String::new, |model_name| format!(" model={model_name}"));
+        let pricing_suffix = if pricing.is_some() {
+            ""
+        } else if model.is_some() {
+            " pricing=estimated-default"
+        } else {
+            ""
+        };
+        vec![
+            format!(
+                "{label}: total_tokens={} input={} output={} cache_write={} cache_read={} estimated_cost={}{}{}",
+                self.total_tokens(),
+                self.input_tokens,
+                self.output_tokens,
+                self.cache_creation_input_tokens,
+                self.cache_read_input_tokens,
+                format_usd(cost.total_cost_usd()),
+                model_suffix,
+                pricing_suffix,
+            ),
+            format!(
+                "  cost breakdown: input={} output={} cache_write={} cache_read={}",
+                format_usd(cost.input_cost_usd),
+                format_usd(cost.output_cost_usd),
+                format_usd(cost.cache_creation_cost_usd),
+                format_usd(cost.cache_read_cost_usd),
+            ),
+        ]
+    }
+}
+
+fn cost_for_tokens(tokens: u32, usd_per_million_tokens: f64) -> f64 {
+    f64::from(tokens) / 1_000_000.0 * usd_per_million_tokens
+}
+
+#[must_use]
+pub fn format_usd(amount: f64) -> String {
+    format!("${amount:.4}")
 }
 
 #[derive(Debug, Clone, Default, PartialEq, Eq)]
@@ -69,7 +210,7 @@ impl UsageTracker {
 
 #[cfg(test)]
 mod tests {
-    use super::{TokenUsage, UsageTracker};
+    use super::{format_usd, pricing_for_model, TokenUsage, UsageTracker};
     use crate::session::{ContentBlock, ConversationMessage, MessageRole, Session};
 
     #[test]
@@ -96,6 +237,53 @@ mod tests {
         assert_eq!(tracker.cumulative_usage().total_tokens(), 48);
     }
 
+    #[test]
+    fn computes_cost_summary_lines() {
+        let usage = TokenUsage {
+            input_tokens: 1_000_000,
+            output_tokens: 500_000,
+            cache_creation_input_tokens: 100_000,
+            cache_read_input_tokens: 200_000,
+        };
+
+        let cost = usage.estimate_cost_usd();
+        assert_eq!(format_usd(cost.input_cost_usd), "$15.0000");
+        assert_eq!(format_usd(cost.output_cost_usd), "$37.5000");
+        let lines = usage.summary_lines_for_model("usage", Some("claude-sonnet-4-20250514"));
+        assert!(lines[0].contains("estimated_cost=$54.6750"));
+        assert!(lines[0].contains("model=claude-sonnet-4-20250514"));
+        assert!(lines[1].contains("cache_read=$0.3000"));
+    }
+
+    #[test]
+    fn supports_model_specific_pricing() {
+        let usage = TokenUsage {
+            input_tokens: 1_000_000,
+            output_tokens: 500_000,
+            cache_creation_input_tokens: 0,
+            cache_read_input_tokens: 0,
+        };
+
+        let haiku = pricing_for_model("claude-haiku-4-5-20251001").expect("haiku pricing");
+        let opus = pricing_for_model("claude-opus-4-6").expect("opus pricing");
+        let haiku_cost = usage.estimate_cost_usd_with_pricing(haiku);
+        let opus_cost = usage.estimate_cost_usd_with_pricing(opus);
+        assert_eq!(format_usd(haiku_cost.total_cost_usd()), "$3.5000");
+        assert_eq!(format_usd(opus_cost.total_cost_usd()), "$52.5000");
+    }
+
+    #[test]
+    fn marks_unknown_model_pricing_as_fallback() {
+        let usage = TokenUsage {
+            input_tokens: 100,
+            output_tokens: 100,
+            cache_creation_input_tokens: 0,
+            cache_read_input_tokens: 0,
+        };
+        let lines = usage.summary_lines_for_model("usage", Some("custom-model"));
+        assert!(lines[0].contains("pricing=estimated-default"));
+    }
+
     #[test]
     fn reconstructs_usage_from_session_messages() {
         let session = Session {

rust/crates/rusty-claude-cli/src/app.rs

@@ -2,7 +2,7 @@ use std::io::{self, Write};
 use std::path::PathBuf;
 
 use crate::args::{OutputFormat, PermissionMode};
-use crate::input::LineEditor;
+use crate::input::{LineEditor, ReadOutcome};
 use crate::render::{Spinner, TerminalRenderer};
 use runtime::{ConversationClient, ConversationMessage, RuntimeError, StreamEvent, UsageSummary};
 
@@ -111,16 +111,21 @@ impl CliApp {
     }
 
     pub fn run_repl(&mut self) -> io::Result<()> {
-        let editor = LineEditor::new("› ");
+        let mut editor = LineEditor::new("› ", Vec::new());
         println!("Rusty Claude CLI interactive mode");
         println!("Type /help for commands. Shift+Enter or Ctrl+J inserts a newline.");
 
-        while let Some(input) = editor.read_line()? {
+        loop {
-            if input.trim().is_empty() {
+            match editor.read_line()? {
-                continue;
+                ReadOutcome::Submit(input) => {
+                    if input.trim().is_empty() {
+                        continue;
+                    }
+                    self.handle_submission(&input, &mut io::stdout())?;
+                }
+                ReadOutcome::Cancel => continue,
+                ReadOutcome::Exit => break,
             }
-
-            self.handle_submission(&input, &mut io::stdout())?;
         }
 
         Ok(())

rust/crates/rusty-claude-cli/src/args.rs

@@ -31,6 +31,10 @@ pub enum Command {
     DumpManifests,
     /// Print the current bootstrap phase skeleton
     BootstrapPlan,
+    /// Start the OAuth login flow
+    Login,
+    /// Clear saved OAuth credentials
+    Logout,
     /// Run a non-interactive prompt and exit
     Prompt { prompt: Vec<String> },
 }
@@ -86,4 +90,13 @@ mod tests {
             })
         );
     }
+
+    #[test]
+    fn parses_login_and_logout_commands() {
+        let login = Cli::parse_from(["rusty-claude-cli", "login"]);
+        assert_eq!(login.command, Some(Command::Login));
+
+        let logout = Cli::parse_from(["rusty-claude-cli", "logout"]);
+        assert_eq!(logout.command, Some(Command::Logout));
+    }
 }

rust/crates/rusty-claude-cli/src/input.rs

@@ -1,9 +1,8 @@
 use std::io::{self, IsTerminal, Write};
 
-use crossterm::cursor::MoveToColumn;
+use crossterm::cursor::{MoveDown, MoveToColumn, MoveUp};
 use crossterm::event::{self, Event, KeyCode, KeyEvent, KeyModifiers};
 use crossterm::queue;
-use crossterm::style::Print;
 use crossterm::terminal::{disable_raw_mode, enable_raw_mode, Clear, ClearType};
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -85,21 +84,124 @@ impl InputBuffer {
         self.buffer.clear();
         self.cursor = 0;
     }
+
+    pub fn replace(&mut self, value: impl Into<String>) {
+        self.buffer = value.into();
+        self.cursor = self.buffer.len();
+    }
+
+    #[must_use]
+    fn current_command_prefix(&self) -> Option<&str> {
+        if self.cursor != self.buffer.len() {
+            return None;
+        }
+        let prefix = &self.buffer[..self.cursor];
+        if prefix.contains(char::is_whitespace) || !prefix.starts_with('/') {
+            return None;
+        }
+        Some(prefix)
+    }
+
+    pub fn complete_slash_command(&mut self, candidates: &[String]) -> bool {
+        let Some(prefix) = self.current_command_prefix() else {
+            return false;
+        };
+
+        let matches = candidates
+            .iter()
+            .filter(|candidate| candidate.starts_with(prefix))
+            .map(String::as_str)
+            .collect::<Vec<_>>();
+        if matches.is_empty() {
+            return false;
+        }
+
+        let replacement = longest_common_prefix(&matches);
+        if replacement == prefix {
+            return false;
+        }
+
+        self.replace(replacement);
+        true
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct RenderedBuffer {
+    lines: Vec<String>,
+    cursor_row: u16,
+    cursor_col: u16,
+}
+
+impl RenderedBuffer {
+    #[must_use]
+    pub fn line_count(&self) -> usize {
+        self.lines.len()
+    }
+
+    fn write(&self, out: &mut impl Write) -> io::Result<()> {
+        for (index, line) in self.lines.iter().enumerate() {
+            if index > 0 {
+                writeln!(out)?;
+            }
+            write!(out, "{line}")?;
+        }
+        Ok(())
+    }
+
+    #[cfg(test)]
+    #[must_use]
+    pub fn lines(&self) -> &[String] {
+        &self.lines
+    }
+
+    #[cfg(test)]
+    #[must_use]
+    pub fn cursor_position(&self) -> (u16, u16) {
+        (self.cursor_row, self.cursor_col)
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum ReadOutcome {
+    Submit(String),
+    Cancel,
+    Exit,
 }
 
 pub struct LineEditor {
     prompt: String,
+    continuation_prompt: String,
+    history: Vec<String>,
+    history_index: Option<usize>,
+    draft: Option<String>,
+    completions: Vec<String>,
 }
 
 impl LineEditor {
     #[must_use]
-    pub fn new(prompt: impl Into<String>) -> Self {
+    pub fn new(prompt: impl Into<String>, completions: Vec<String>) -> Self {
         Self {
             prompt: prompt.into(),
+            continuation_prompt: String::from("> "),
+            history: Vec::new(),
+            history_index: None,
+            draft: None,
+            completions,
         }
     }
 
-    pub fn read_line(&self) -> io::Result<Option<String>> {
+    pub fn push_history(&mut self, entry: impl Into<String>) {
+        let entry = entry.into();
+        if entry.trim().is_empty() {
+            return;
+        }
+        self.history.push(entry);
+        self.history_index = None;
+        self.draft = None;
+    }
+
+    pub fn read_line(&mut self) -> io::Result<ReadOutcome> {
         if !io::stdin().is_terminal() || !io::stdout().is_terminal() {
             return self.read_line_fallback();
         }
@@ -107,29 +209,43 @@ impl LineEditor {
         enable_raw_mode()?;
         let mut stdout = io::stdout();
         let mut input = InputBuffer::new();
-        self.redraw(&mut stdout, &input)?;
+        let mut rendered_lines = 1usize;
+        self.redraw(&mut stdout, &input, rendered_lines)?;
 
         loop {
             let event = event::read()?;
             if let Event::Key(key) = event {
-                match Self::handle_key(key, &mut input) {
+                match self.handle_key(key, &mut input) {
-                    EditorAction::Continue => self.redraw(&mut stdout, &input)?,
+                    EditorAction::Continue => {
+                        rendered_lines = self.redraw(&mut stdout, &input, rendered_lines)?;
+                    }
                     EditorAction::Submit => {
                         disable_raw_mode()?;
                         writeln!(stdout)?;
-                        return Ok(Some(input.as_str().to_owned()));
+                        self.history_index = None;
+                        self.draft = None;
+                        return Ok(ReadOutcome::Submit(input.as_str().to_owned()));
                     }
                     EditorAction::Cancel => {
                         disable_raw_mode()?;
                         writeln!(stdout)?;
-                        return Ok(None);
+                        self.history_index = None;
+                        self.draft = None;
+                        return Ok(ReadOutcome::Cancel);
+                    }
+                    EditorAction::Exit => {
+                        disable_raw_mode()?;
+                        writeln!(stdout)?;
+                        self.history_index = None;
+                        self.draft = None;
+                        return Ok(ReadOutcome::Exit);
                     }
                 }
             }
         }
     }
 
-    fn read_line_fallback(&self) -> io::Result<Option<String>> {
+    fn read_line_fallback(&self) -> io::Result<ReadOutcome> {
         let mut stdout = io::stdout();
         write!(stdout, "{}", self.prompt)?;
         stdout.flush()?;
@@ -137,22 +253,32 @@ impl LineEditor {
         let mut buffer = String::new();
         let bytes_read = io::stdin().read_line(&mut buffer)?;
         if bytes_read == 0 {
-            return Ok(None);
+            return Ok(ReadOutcome::Exit);
         }
 
         while matches!(buffer.chars().last(), Some('\n' | '\r')) {
             buffer.pop();
         }
-        Ok(Some(buffer))
+        Ok(ReadOutcome::Submit(buffer))
     }
 
-    fn handle_key(key: KeyEvent, input: &mut InputBuffer) -> EditorAction {
+    #[allow(clippy::too_many_lines)]
+    fn handle_key(&mut self, key: KeyEvent, input: &mut InputBuffer) -> EditorAction {
         match key {
             KeyEvent {
                 code: KeyCode::Char('c'),
                 modifiers,
                 ..
-            } if modifiers.contains(KeyModifiers::CONTROL) => EditorAction::Cancel,
+            } if modifiers.contains(KeyModifiers::CONTROL) => {
+                if input.as_str().is_empty() {
+                    EditorAction::Exit
+                } else {
+                    input.clear();
+                    self.history_index = None;
+                    self.draft = None;
+                    EditorAction::Cancel
+                }
+            }
             KeyEvent {
                 code: KeyCode::Char('j'),
                 modifiers,
@@ -194,6 +320,25 @@ impl LineEditor {
                 input.move_right();
                 EditorAction::Continue
             }
+            KeyEvent {
+                code: KeyCode::Up, ..
+            } => {
+                self.navigate_history_up(input);
+                EditorAction::Continue
+            }
+            KeyEvent {
+                code: KeyCode::Down,
+                ..
+            } => {
+                self.navigate_history_down(input);
+                EditorAction::Continue
+            }
+            KeyEvent {
+                code: KeyCode::Tab, ..
+            } => {
+                input.complete_slash_command(&self.completions);
+                EditorAction::Continue
+            }
             KeyEvent {
                 code: KeyCode::Home,
                 ..
@@ -211,6 +356,8 @@ impl LineEditor {
                 code: KeyCode::Esc, ..
             } => {
                 input.clear();
+                self.history_index = None;
+                self.draft = None;
                 EditorAction::Cancel
             }
             KeyEvent {
@@ -219,22 +366,74 @@ impl LineEditor {
                 ..
             } if modifiers.is_empty() || modifiers == KeyModifiers::SHIFT => {
                 input.insert(ch);
+                self.history_index = None;
+                self.draft = None;
                 EditorAction::Continue
             }
             _ => EditorAction::Continue,
         }
     }
 
-    fn redraw(&self, out: &mut impl Write, input: &InputBuffer) -> io::Result<()> {
+    fn navigate_history_up(&mut self, input: &mut InputBuffer) {
-        let display = input.as_str().replace('\n', "\\n\n> ");
+        if self.history.is_empty() {
+            return;
+        }
+
+        match self.history_index {
+            Some(0) => {}
+            Some(index) => {
+                let next_index = index - 1;
+                input.replace(self.history[next_index].clone());
+                self.history_index = Some(next_index);
+            }
+            None => {
+                self.draft = Some(input.as_str().to_owned());
+                let next_index = self.history.len() - 1;
+                input.replace(self.history[next_index].clone());
+                self.history_index = Some(next_index);
+            }
+        }
+    }
+
+    fn navigate_history_down(&mut self, input: &mut InputBuffer) {
+        let Some(index) = self.history_index else {
+            return;
+        };
+
+        if index + 1 < self.history.len() {
+            let next_index = index + 1;
+            input.replace(self.history[next_index].clone());
+            self.history_index = Some(next_index);
+            return;
+        }
+
+        input.replace(self.draft.take().unwrap_or_default());
+        self.history_index = None;
+    }
+
+    fn redraw(
+        &self,
+        out: &mut impl Write,
+        input: &InputBuffer,
+        previous_line_count: usize,
+    ) -> io::Result<usize> {
+        let rendered = render_buffer(&self.prompt, &self.continuation_prompt, input);
+        if previous_line_count > 1 {
+            queue!(out, MoveUp(saturating_u16(previous_line_count - 1)))?;
+        }
+        queue!(out, MoveToColumn(0), Clear(ClearType::FromCursorDown),)?;
+        rendered.write(out)?;
         queue!(
             out,
+            MoveUp(saturating_u16(rendered.line_count().saturating_sub(1))),
             MoveToColumn(0),
-            Clear(ClearType::CurrentLine),
-            Print(&self.prompt),
-            Print(display),
         )?;
-        out.flush()
+        if rendered.cursor_row > 0 {
+            queue!(out, MoveDown(rendered.cursor_row))?;
+        }
+        queue!(out, MoveToColumn(rendered.cursor_col))?;
+        out.flush()?;
+        Ok(rendered.line_count())
     }
 }
 
@@ -243,11 +442,76 @@ enum EditorAction {
     Continue,
     Submit,
     Cancel,
+    Exit,
+}
+
+#[must_use]
+pub fn render_buffer(
+    prompt: &str,
+    continuation_prompt: &str,
+    input: &InputBuffer,
+) -> RenderedBuffer {
+    let before_cursor = &input.as_str()[..input.cursor];
+    let cursor_row = saturating_u16(before_cursor.chars().filter(|ch| *ch == '\n').count());
+    let cursor_line = before_cursor.rsplit('\n').next().unwrap_or_default();
+    let cursor_prompt = if cursor_row == 0 {
+        prompt
+    } else {
+        continuation_prompt
+    };
+    let cursor_col = saturating_u16(cursor_prompt.chars().count() + cursor_line.chars().count());
+
+    let mut lines = Vec::new();
+    for (index, line) in input.as_str().split('\n').enumerate() {
+        let prefix = if index == 0 {
+            prompt
+        } else {
+            continuation_prompt
+        };
+        lines.push(format!("{prefix}{line}"));
+    }
+    if lines.is_empty() {
+        lines.push(prompt.to_string());
+    }
+
+    RenderedBuffer {
+        lines,
+        cursor_row,
+        cursor_col,
+    }
+}
+
+#[must_use]
+fn longest_common_prefix(values: &[&str]) -> String {
+    let Some(first) = values.first() else {
+        return String::new();
+    };
+
+    let mut prefix = (*first).to_string();
+    for value in values.iter().skip(1) {
+        while !value.starts_with(&prefix) {
+            prefix.pop();
+            if prefix.is_empty() {
+                break;
+            }
+        }
+    }
+    prefix
+}
+
+#[must_use]
+fn saturating_u16(value: usize) -> u16 {
+    u16::try_from(value).unwrap_or(u16::MAX)
 }
 
 #[cfg(test)]
 mod tests {
-    use super::InputBuffer;
+    use super::{render_buffer, InputBuffer, LineEditor};
+    use crossterm::event::{KeyCode, KeyEvent, KeyModifiers};
+
+    fn key(code: KeyCode) -> KeyEvent {
+        KeyEvent::new(code, KeyModifiers::NONE)
+    }
 
     #[test]
     fn supports_basic_line_editing() {
@@ -266,4 +530,119 @@ mod tests {
         assert_eq!(input.as_str(), "hix");
         assert_eq!(input.cursor(), 2);
     }
+
+    #[test]
+    fn completes_unique_slash_command() {
+        let mut input = InputBuffer::new();
+        for ch in "/he".chars() {
+            input.insert(ch);
+        }
+
+        assert!(input.complete_slash_command(&[
+            "/help".to_string(),
+            "/hello".to_string(),
+            "/status".to_string(),
+        ]));
+        assert_eq!(input.as_str(), "/hel");
+
+        assert!(input.complete_slash_command(&["/help".to_string(), "/status".to_string()]));
+        assert_eq!(input.as_str(), "/help");
+    }
+
+    #[test]
+    fn ignores_completion_when_prefix_is_not_a_slash_command() {
+        let mut input = InputBuffer::new();
+        for ch in "hello".chars() {
+            input.insert(ch);
+        }
+
+        assert!(!input.complete_slash_command(&["/help".to_string()]));
+        assert_eq!(input.as_str(), "hello");
+    }
+
+    #[test]
+    fn history_navigation_restores_current_draft() {
+        let mut editor = LineEditor::new("› ", vec![]);
+        editor.push_history("/help");
+        editor.push_history("status report");
+
+        let mut input = InputBuffer::new();
+        for ch in "draft".chars() {
+            input.insert(ch);
+        }
+
+        let _ = editor.handle_key(key(KeyCode::Up), &mut input);
+        assert_eq!(input.as_str(), "status report");
+
+        let _ = editor.handle_key(key(KeyCode::Up), &mut input);
+        assert_eq!(input.as_str(), "/help");
+
+        let _ = editor.handle_key(key(KeyCode::Down), &mut input);
+        assert_eq!(input.as_str(), "status report");
+
+        let _ = editor.handle_key(key(KeyCode::Down), &mut input);
+        assert_eq!(input.as_str(), "draft");
+    }
+
+    #[test]
+    fn tab_key_completes_from_editor_candidates() {
+        let mut editor = LineEditor::new(
+            "› ",
+            vec![
+                "/help".to_string(),
+                "/status".to_string(),
+                "/session".to_string(),
+            ],
+        );
+        let mut input = InputBuffer::new();
+        for ch in "/st".chars() {
+            input.insert(ch);
+        }
+
+        let _ = editor.handle_key(key(KeyCode::Tab), &mut input);
+        assert_eq!(input.as_str(), "/status");
+    }
+
+    #[test]
+    fn renders_multiline_buffers_with_continuation_prompt() {
+        let mut input = InputBuffer::new();
+        for ch in "hello\nworld".chars() {
+            if ch == '\n' {
+                input.insert_newline();
+            } else {
+                input.insert(ch);
+            }
+        }
+
+        let rendered = render_buffer("› ", "> ", &input);
+        assert_eq!(
+            rendered.lines(),
+            &["› hello".to_string(), "> world".to_string()]
+        );
+        assert_eq!(rendered.cursor_position(), (1, 7));
+    }
+
+    #[test]
+    fn ctrl_c_exits_only_when_buffer_is_empty() {
+        let mut editor = LineEditor::new("› ", vec![]);
+        let mut empty = InputBuffer::new();
+        assert!(matches!(
+            editor.handle_key(
+                KeyEvent::new(KeyCode::Char('c'), KeyModifiers::CONTROL),
+                &mut empty,
+            ),
+            super::EditorAction::Exit
+        ));
+
+        let mut filled = InputBuffer::new();
+        filled.insert('x');
+        assert!(matches!(
+            editor.handle_key(
+                KeyEvent::new(KeyCode::Char('c'), KeyModifiers::CONTROL),
+                &mut filled,
+            ),
+            super::EditorAction::Cancel
+        ));
+        assert!(filled.as_str().is_empty());
+    }
 }

rust/crates/tools/.gitignore

@@ -0,0 +1 @@
+.clawd-agents/

rust/crates/tools/Cargo.toml

@@ -7,6 +7,7 @@ publish.workspace = true
 
 [dependencies]
 runtime = { path = "../runtime" }
+reqwest = { version = "0.12", default-features = false, features = ["blocking", "rustls-tls"] }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"