fix(responses): flatten the Codex 0.147 functions namespace in the parser (lands #1896 subset)

[lidge-jun]

Summary

Lands the load-bearing subset of contributor PR #1896: namespace groups named functions (Codex 0.147's reserved grouping) flatten their children as top-level tools — including nested custom freeform tools like code-mode exec — while other namespaces keep MCP-style round-trip routing. The hardcoded exec/mcp_* name lists from the original are deliberately dropped pending a catalog-helper approach.

Verification

• responses-tool-conformance + cursor-native-exec + cursor-live-transport: 60/0
• tsc --noEmit clean

Checklist

• Regression test included (flatten + code-mode detection)
• Typecheck green
• No GUI change (no screenshot required)

Summary by CodeRabbit

• New Features

  • Improved support for custom tools, including freeform tool handling and specialized guidance for patch-based tools.
  • Added support for nested tool namespaces while preserving namespace information where applicable.
  • Enabled code mode detection for supported requests.

• Bug Fixes

  • Built-in function tools are now presented without unnecessary namespace metadata.

[github-actions]

✅ Deterministic PR hygiene checks passed.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: 94d00737-3690-4a8a-b852-9e49c4140c68

📥 Commits

Reviewing files that changed from the base of the PR and between 542ea37 and 5f2b939.

📒 Files selected for processing (2)

• src/responses/parser.ts
• tests/responses-tool-conformance.test.ts

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📝 Walkthrough

Walkthrough

The parser centralizes freeform custom-tool conversion, adds apply_patch guidance, flattens reserved functions namespaces, and preserves other namespaces. Conformance tests verify nested Codex tools and code mode detection.

Changes

Responses tool normalization

Layer / File(s)	Summary
Tool conversion and namespace wiring src/responses/parser.ts, tests/responses-tool-conformance.test.ts	buildTools uses shared pushCustom conversion for freeform tools and applies apply_patch guidance. Reserved functions namespaces flatten without namespace metadata, while other namespaces retain it. Tests cover freeform flags, namespace metadata, and code mode detection.

Estimated code review effort: 2 (Simple) | ~10 minutes

Suggested reviewers: wibias

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/land-1896

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