fix(chat-headers): skip x-initiator override for @ai-sdk/github-copilot models

[zhzy0077]

Summary

Fixes the Bad Request: bad request: error: invalid initiator error that occurs when subagents are scheduled via oh-my-opencode on GitHub Copilot providers.

Root Cause

OpenCode recently switched all Copilot models to use @ai-sdk/github-copilot (copilot.ts:56). This SDK package has its own fetch wrapper that sets x-initiator based on the actual HTTP request body — if the last message is role: "user", it sets x-initiator: user.

oh-my-opencode's chat.headers hook was overriding this with x-initiator: agent (because it detected the <!-- OMO_INTERNAL_INITIATOR --> marker). The Copilot API then saw a mismatch between the header (agent) and the request body content (role: "user") and rejected the request.

OpenCode's own chat.headers handler already handles this correctly — it explicitly skips @ai-sdk/github-copilot models because the fetch wrapper handles x-initiator on its own:
PR: anomalyco/opencode#13485

// opencode/packages/opencode/src/plugin/copilot.ts:311-314
// Skip x-initiator override when using @ai-sdk/github-copilot - it has its own
// fetch wrapper that sets x-initiator based on message content, and overriding
// it here causes "invalid initiator" validation errors from Copilot API
if (incoming.model.api.npm === "@ai-sdk/github-copilot") return

Fix

Skip the x-initiator override when model.api.npm === "@ai-sdk/github-copilot", matching OpenCode's approach.

Changes

• src/plugin/chat-headers.ts — Check model.api.npm and skip override for @ai-sdk/github-copilot
• src/plugin/chat-headers.test.ts — Added test for the skip behavior

---

Summary by cubic

Skip x-initiator override for @ai-sdk/github-copilot models to prevent “invalid initiator” errors on Copilot requests. This matches OpenCode’s behavior and restores successful subagent scheduling.

• Bug Fixes
  • Do not set x-initiator when model.api.npm === "@ai-sdk/github-copilot".
  • Added a test to verify the skip behavior.

^{Written for commit 890a737. Summary will update on new commits.}

[github-actions]

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[cubic-dev-ai]

No issues found across 2 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

_{Auto-approved: Fixes 'invalid initiator' error for Copilot by aligning with upstream SDK handling. Minimal logic change with defensive checks and verified by tests.}

[zhzy0077]

I have read the CLA Document and I hereby sign the CLA