fix(api): restore function_call name on non-streaming /v1/responses

[diegosouzapw]

Closes #12370

Root cause

open-sse/handlers/chatCore/nonStreamingClientTranslate.ts:132-138 — the #7936 identity-restore loop for non-streaming /v1/responses function_call output items:

const identity = requestToolIdentityMap.get(item.name);
if (identity) {
  item.namespace = identity.namespace;
  item.name = identity.name;
}

requestToolIdentityMap is typed Map<string, {namespace, name}>, but extractRequestToolIdentityMap() (open-sse/handlers/chatCore/requestToolIdentity.ts) falls back to the _toolNameMap side channel whenever no namespace tools were declared on the request. For a Gemini/Claude pivot that side channel is a plain Map<string, string> alias table ("shell" -> "shell"), not a {namespace, name} identity — a fact the code comment there already documents (#9780), but the consumer in nonStreamingClientTranslate.ts never checked the shape.

For Codex's plain (non-namespace) shell function tool, identity comes back as the string "shell". ("shell").namespace and ("shell").name are both undefined, so the loop overwrote a perfectly valid item.name ("shell") with undefined — a key JSON.stringify drops entirely. Codex then receives a function_call with no name, can't dispatch it, and re-narrates its intent instead — the reported loop.

Fix: only apply the restore when identity actually has the {namespace, name} shape (typeof identity === "object" && typeof identity.name === "string").

Live VPS evidence (192.168.0.15, real gemini API key, Codex-shaped payload: tool_choice: "auto", one shell function tool, gemini/gemini-3-flash-preview)

POST /v1/chat/completions  (stream:false)  → CORRECT
  tool_calls[0] = {"id":"call_257465","type":"function",
                   "function":{"name":"shell","arguments":"{\"command\":[\"ls memory-bank/\"]}"}}

POST /v1/responses  (stream:false)  → BUG — no `name` (reproduced 3/3)
  output[0] = {"id":"fc_call_8223","type":"function_call","call_id":"call_8223",
               "arguments":"{\"command\":[\"ls\",\"memory-bank/\"]}"}

POST /v1/responses  (stream:true)   → CORRECT
  response.output_item.added item = {"type":"function_call","arguments":"",
                                     "call_id":"call_165396","name":"shell","status":"in_progress"}

TDD — RED → GREEN

New test tests/unit/non-streaming-client-translate.test.ts → "#12370: alias-shaped requestToolIdentityMap must not blank out function_call name", feeding translateNonStreamingClientResponse() a Gemini functionCall response plus an alias-shaped requestToolIdentityMap (Map(["shell","shell"])), matching the live-VPS shape.

RED (guard removed):

✖ #12370: alias-shaped requestToolIdentityMap must not blank out function_call name (19.021283ms)
  AssertionError [ERR_ASSERTION]: name must survive the alias-map fallback
  + actual - expected
  + undefined
  - 'shell'

GREEN (fix applied) — full file, 11/11 pass:

✔ #12370: alias-shaped requestToolIdentityMap must not blank out function_call name (12.826964ms)
...
ℹ tests 11
ℹ pass 11
ℹ fail 0

Also confirmed the pre-existing #7936 regression test (genuine {namespace, name} restore, e.g. mcp__server__tool) is unaffected — still green, unmodified.

Gates run

• node scripts/check/check-file-size.mjs — no new violation on touched files
• node scripts/check/check-complexity.mjs — OK (2826 violations vs. baseline 3218)
• node scripts/check/check-cognitive-complexity.mjs — OK (1276 violations vs. baseline 1437)
• npm run typecheck:core — exit 0
• npm run check:open-sse-typecheck — OK, 0 pre-existing errors
• npx eslint --suppressions-location config/quality/eslint-suppressions.json <changed files> — exit 0
• node --import tsx/esm --test tests/unit/non-streaming-client-translate.test.ts — 11/11 pass
• Related identity-map regression suites also re-run green and unmodified: tests/unit/chatcore-response-toolname-map-recovery.test.ts, tests/unit/9780-namespace-identity-pivot.test.ts, tests/unit/translator-resp-openai-responses-namespace-identity.test.ts
• node scripts/check/check-changelog-integrity.mjs — OK
• Pre-commit hooks (lint-staged, docs-sync, any-budget:t11, tracked-artifacts) — all passed at commit time
• Base-green check: no open base-red issue for release/v3.8.51; branch fast-forwarded onto the current tip (cde49c9) before opening this PR

Note for a maintainer (not fixed here, out of scope for this failing test)

open-sse/utils/stream.ts::restoreResponsesPassthroughFunctionCallIdentity (the native-Codex-passthrough streaming counterpart) has the identical unguarded identity.namespace/identity.name shape assumption. It isn't currently reachable with an alias-shaped map (the alias _toolNameMap is only published by the non-passthrough Gemini/Claude pivot, which doesn't feed the codex-native passthrough branch), so no failing test proves it broken today — flagging as a latent variant worth a follow-up look rather than fixing speculatively.