Greptile Summary

This PR rebases a prior fix (#55483) cleanly onto main, adding a description to the streamTo field in SessionsSpawnToolSchema to document it as ACP-only, and logging the change in CHANGELOG.md.

The only code change is replacing optionalStringEnum(ACP_SPAWN_STREAM_TARGETS) with an inline Type.Optional(Type.String({ enum: [...], description: ... })). While the JSON Schema output is functionally equivalent, the added description contains a factual inaccuracy: it states streamTo is "currently ignored for subagent spawns" when the execute handler (lines 136–141, unchanged by this PR) actually returns an explicit error response whenever streamTo is provided for runtime !== "acp". Callers relying on the schema description will be misled into thinking the field is silently accepted, when it is not.

• P1: streamTo schema description says "ignored for subagent spawns" but the runtime returns { status: "error", error: "streamTo is only supported for runtime=acp; …" } — documentation and behavior are inconsistent.
• Minor: switching from optionalStringEnum (which emits Type.Unsafe<"parent"> for a precise TypeScript type) to Type.String() slightly weakens the TypeScript type of the field from "parent" | undefined to string | undefined, though this has no runtime impact since the value is manually narrowed at line 114.

Confidence Score: 4/5

Safe to merge after resolving the schema description mismatch — either update the description to reflect the error behavior or remove lines 136-141 to truly ignore the field.

One P1 finding: the newly added schema description says streamTo is 'ignored for subagent spawns' but the code returns an explicit error, misleading callers who rely on the documented contract.

src/agents/tools/sessions-spawn-tool.ts — description at lines 44-50 and the guard block at lines 136-141 need to be reconciled.

This is a comment left during a code review.
Path: src/agents/tools/sessions-spawn-tool.ts
Line: 44-50

Comment:
**Schema description contradicts actual runtime behavior**

The description states `"currently ignored for subagent spawns"`, but the execute handler at lines 136–141 returns an explicit error response when `streamTo` is supplied for a non-ACP runtime:

```ts
if (streamTo && runtime !== "acp") {
  return jsonResult({
    status: "error",
    error: `streamTo is only supported for runtime=acp; got runtime=${runtime}`,
  });
}
```

A caller reading this schema description will expect that passing `streamTo` to a subagent spawn is silently accepted/ignored, but they will actually receive an error response at runtime.

If the intent (as the PR title and description suggest) was to **truly ignore** `streamTo` for subagent spawns, the guard block at lines 136–141 should have been removed so the field is silently dropped. If the intent was simply to document the existing "unsupported" constraint, the description should say `"not supported for subagent spawns"` (or similar) rather than `"ignored"`.

Suggested fix (documenting the actual behavior):
```suggestion
  streamTo: Type.Optional(
    Type.String({
      enum: [...ACP_SPAWN_STREAM_TARGETS],
      description:
        'ACP-only output routing hint. Only used for runtime="acp"; passing it for subagent spawns returns an error.',
    }),
  ),
```

How can I resolve this? If you propose a fix, please make it concise.

_{Reviews (1): Last reviewed commit: "fix(agents): ignore acp-only streamTo on..." | Re-trigger Greptile}

closing as superseded by current main. src/agents/tools/sessions-spawn-tool.ts now treats streamTo as ACP-only and rejects it outside runtime="acp", with coverage in src/agents/tools/sessions-spawn-tool.test.ts. the old branch conflicts and its ignore behavior is weaker than the current explicit rejection.