[Bug] litellm ContextWindowExceededError not detected as context overflow

[fabian33-ops]

Description

litellm wraps provider context-overflow errors as ContextWindowExceededError: litellm.BadRequestError: Context Window exceeded for given call. No models have context window large enough for this call.

The shared overflow matcher in packages/llm/src/provider-error.ts doesn't recognize the phrase "context window exceeded", so these errors are classified as a generic API error instead of context overflow. This means compaction is never triggered and the session dead-ends.

Plugins

OpenCode version

0.0.0-dev-202608241310

Steps to reproduce

1. Use a model behind litellm
2. Set the model max_input_tokens below the serving engines' max contect window, so we see the error from litellm, instead of the error message from the serving engine, being automaticall detected by opencode.
3. Send enough messages to exceed the litellm context window
4. Observe the error is treated as a generic API failure rather than triggering automatic compaction

Screenshot and/or share link

Operating System

15.7.9 (24G830)

Terminal

zsh

[github-actions]

This issue might be a duplicate of (or closely related to) an existing issue. Please check:

• Image-count 400s (Azure: "Exceeded maximum number of images (50)") are not classified as context overflow, so media-strip compaction never triggers #39677: Same root cause — an error not matched by the patterns in packages/llm/src/provider-error.ts means compaction never triggers. That report covers Azure's image-count 400; this one covers litellm's ContextWindowExceededError phrasing. The fix would be in the same place, so these may be best addressed together.