[codex] feat(ai plugin): support custom request options

[jn12-29]

Summary

Adds per-request AI options for plugin calls:

• passes custom headers through to the OpenAI SDK request options
• passes extraBody fields into chat completion request bodies
• keeps runtime-owned fields (model, messages, tools, stream) protected from extraBody overrides

Validation

• pnpm run typecheck:node
• pnpm build:unpack
• node _work/2026-06-08-ai-extra-body/verify-ai-extra-body-dev.js
• git -C _work/pr-ai-extra-body-submit diff --check upstream/main..HEAD

[gemini-code-assist]

Code Review

This pull request introduces support for custom headers and extra OpenAI-compatible request body fields (extraBody) in the AI plugin API. It adds validation and normalization helpers (isPlainObject, normalizeHeaders, and normalizeExtraBody) to process these inputs before passing them to the OpenAI client. The review feedback suggests improving the robustness of these helpers by implementing stricter plain object validation, handling null values safely, and preventing the stringification of null or undefined header values.

Important

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[gemini-code-assist]

There are a few areas where robustness and correctness can be improved:

1. Stricter Plain Object Validation: The current isPlainObject implementation returns true for instances of Date, RegExp, Map, Set, etc. Checking the prototype using Object.getPrototypeOf ensures only plain objects are accepted.
2. Defensive Programming (Null Safety): The current checks only handle undefined. If null is passed (which is common in JSON/IPC payloads), it will fail the isPlainObject check and throw an error. Using == null safely handles both null and undefined.
3. Header Stringification Pitfall: Using String(value) directly on object entries can convert null or undefined values to "null" or "undefined" strings, which will be sent as actual header values. It is safer to filter out null and undefined values before stringifying.

  private isPlainObject(value: unknown): value is Record<string, unknown> {
    if (typeof value !== 'object' || value === null) return false
    const proto = Object.getPrototypeOf(value)
    return proto === null || proto === Object.prototype
  }

  private normalizeHeaders(headers: unknown): Record<string, string> | undefined {
    if (headers == null) return undefined
    if (!this.isPlainObject(headers)) {
      throw new Error('headers 必须是对象')
    }

    const normalized: Record<string, string> = {}
    for (const [key, value] of Object.entries(headers)) {
      if (value !== null && value !== undefined) {
        normalized[key] = String(value)
      }
    }
    return Object.keys(normalized).length > 0 ? normalized : undefined
  }

  private normalizeExtraBody(extraBody: unknown): Record<string, unknown> | undefined {
    if (extraBody == null) return undefined
    if (!this.isPlainObject(extraBody)) {
      throw new Error('extraBody 必须是对象')
    }

    const normalized = { ...extraBody }
    for (const key of RESERVED_EXTRA_BODY_KEYS) {
      delete normalized[key]
    }
    return Object.keys(normalized).length > 0 ? normalized : undefined
  }

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

This PR extends the plugin AI API to allow callers to pass additional HTTP headers and OpenAI-compatible extra request body fields, forwarding them through the OpenAI SDK request.

Changes:

• Added headers and extraBody to AiOption.
• Added normalization helpers to validate/normalize headers and extra body fields.
• Wired headers and extraBody into both non-streaming and streaming chat completion requests.

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