fix(codex): drop local_shell tool (no longer supported upstream)

[KooshaPari]

Summary

Drop the deprecated local_shell hosted tool type from the Codex executor before forwarding requests to OpenAI's Responses API. This resolves the omni-combo 400 "The local_shell tool is no longer supported." spike on POST /v1/chat/completions routed through the codex provider.

Context

OpenAI removed the local_shell hosted tool type from the Responses API. When Codex CLI injects { type: "local_shell" } into body.tools (or sets body.tool_choice = { type: "local_shell" }), OpenAI's Responses API now returns 400 with the error message:

The local_shell tool is no longer supported.

The Codex executor in OmniRoute whitelists a set of hosted tool types in CODEX_HOSTED_TOOL_TYPES (file: open-sse/executors/codex.ts:399) so that the normalizeCodexTools preprocessor preserves them instead of stripping them. The set previously included local_shell. Because local_shell was whitelisted, the executor forwarded the now-rejected type unchanged and the request 400'd.

There is already a precedent in this file for handling tools that are in the whitelist but no longer accepted by upstream — #2980 adds a dropImageGeneration option for free-plan accounts that can't run image_generation. The cleanest, least-invasive fix is to remove local_shell from the whitelist entirely (it is rejected regardless of account plan) and add a defensive branch in the tool_choice cleanup so a local_shell request-level tool choice is dropped instead of forwarded.

Changes

• open-sse/executors/codex.ts

  • Remove "local_shell" from the CODEX_HOSTED_TOOL_TYPES set. normalizeCodexTools will now route it to the existing console.debug("dropping unknown hosted tool type: ...") branch and filter it from body.tools before the request reaches OpenAI.
  • Add a toolChoice.type === "local_shell" branch in normalizeCodexTools that deletes body.tool_choice, mirroring the existing handling of stale tool_choice = { type: "function", name: <unknown> }.
  • Add a comment above the whitelist explaining why local_shell is intentionally absent so future contributors don't accidentally re-add it.

• tests/unit/executor-codex.test.ts

  • New regression test CodexExecutor.transformRequest drops Codex local_shell tool (no longer supported upstream) that asserts both:
    1. body.tools entries with type: "local_shell" are dropped while sibling tools are preserved.
    2. body.tool_choice = { type: "local_shell" } is dropped rather than forwarded.

Key Implementation Details

• The fix is symmetric to the existing dropImageGeneration pattern (#2980) but does not introduce a new option/flag — local_shell is universally rejected by upstream, so there is no per-account gating needed.
• The console.debug branch in normalizeCodexTools ([Codex] dropping unknown hosted tool type: local_shell) gives operators visibility when the fix is exercised.
• No new exports or API surface changes; this is a strictly behavior-preserving fix for a specific upstream-incompatible tool type.
• OmniRoute-clean's pre-commit hooks (prettier, eslint, docs-sync, check:any-budget:t11, check-tracked-artifacts) all pass on the commit.

Use Cases

• Restores /v1/chat/completions routing through the codex executor that currently fails with 400 whenever Codex CLI is on the request path. Before this fix, most codex calls were failing (per the observed metrics); after this fix, they succeed.
• Closes the gap for users on codex/gpt-5.4-mini and other Codex-CLI-spawned requests that automatically inject local_shell.

Testing

The change was developed and validated against OmniRoute-fresh2 (which has the same executor), then cherry-picked cleanly onto OmniRoute-clean at the Release v3.8.34 base so the PR diff is minimal.

# Run the new regression test (and the existing hosted-tools test for regression):
node --import tsx \
  --import ./open-sse/utils/setupPolyfill.ts \
  --import ./tests/_setup/isolateDataDir.ts \
  --test --test-name-pattern="drops Codex local_shell|preserves namespace MCP tools" \
  tests/unit/executor-codex.test.ts

Expected output:

[Codex] dropping unknown hosted tool type: local_shell
[Codex] dropping unknown hosted tool type: unknown_hosted_tool
✔ CodexExecutor.transformRequest drops Codex local_shell tool (no longer supported upstream)
✔ CodexExecutor.transformRequest preserves namespace MCP tools and hosted tool types
ℹ tests 2
ℹ pass 2
ℹ fail 0

To smoke-test end-to-end against a live Codex account, send any request that would have Codex CLI inject local_shell (e.g. a tool-using prompt through Codex CLI routed via omni-combo / codex combo) and verify it returns 200 instead of 400.

Links

• Related upstream signal: Codex CLI currently injects { type: "local_shell" } into every Responses request regardless of plan; OpenAI has removed it from the Responses API and now 400s on it.
• Mirrors the dropImageGeneration pattern introduced in #2980 for image_generation on free-plan Codex accounts.

[gemini-code-assist]

Code Review

This pull request removes the local_shell tool from the Codex executor because OpenAI has deprecated and removed it from the Responses API. The changes ensure that local_shell is removed from the hosted tool types and that any tool_choice specifying local_shell is deleted before forwarding. A new unit test has been added to verify these changes. There are no review comments, so I have no feedback to provide.

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