From d5620c06b1e892a5e24615da8b885034264338e6 Mon Sep 17 00:00:00 2001
From: bellman <bellman@bellmanui-MacBookAir.local>
Date: Fri, 15 May 2026 10:34:24 +0900
Subject: [PATCH] Document provider compatibility diagnostics and passthrough

Explain the provider compatibility behavior that now has executable coverage so future changes preserve routing, custom gateway slugs, diagnostics, and extra-body passthrough semantics.

Constraint: Task 2 requires docs/status evidence while leader owns Ultragoal checkpoints and .omx/ultragoal remains untouched.
Rejected: Add a new CLI status command | broader than the assigned provider compatibility documentation/status surface.
Confidence: high
Scope-risk: narrow
Directive: Keep docs aligned with provider_diagnostics_for_model, MessageRequest::extra_body, and OpenAI-compatible slash-model tests.
Tested: cargo test --manifest-path rust/Cargo.toml -p api custom_openai_gateway_preserves_slash_model_ids_and_extra_body_params; cargo test --manifest-path rust/Cargo.toml -p api provider_diagnostics_explain_openai_compatible_capabilities; cargo check --manifest-path rust/Cargo.toml -p api
Not-tested: Live provider calls requiring external credentials.
Co-authored-by: OmX <omx@local>