chat/ is derived from the Vercel AI SDK @ai-sdk/openai-compatible chat implementation.
responses/ is derived from the Vercel AI SDK @ai-sdk/openai Responses implementation.
The exact upstream revisions originally copied into this repository are unknown. Current dependency versions and the VERSION constant in copilot-provider.ts are not copy provenance.

Ownership

Keep chat/ and responses/ structurally close to their upstream modules, but preserve the intentional Copilot adaptations: the copilot options and metadata namespace, thinking_budget, reasoning text and opaque reasoning, stateless Responses requests with encrypted reasoning, rotating response item IDs, and explicit function-tool strictness taking precedence over the global fallback.

copilot-provider.ts is the local adapter assembly entrypoint used by plugin/provider/github-copilot.ts. models.ts is OpenCode-owned catalog reconciliation, not vendored SDK code. Authentication, request headers, model routing, and integration lifecycle are also owned by the provider plugin.

When updating the upstream-shaped modules, compare against both source packages and reapply the documented Copilot adaptations. Focused regression coverage is in:

test/github-copilot/copilot-chat-model.test.ts
test/github-copilot/convert-to-copilot-messages.test.ts
test/github-copilot/openai-responses-language-model.test.ts
test/github-copilot/openai-responses-prepare-tools.test.ts
test/github-copilot/models.test.ts
test/plugin/provider-github-copilot.test.ts