test(antigravity): assert converted chat.completion for non-stream 429 retry

The executor's non-streaming path collects the upstream SSE and returns a
finished OpenAI chat.completion payload. The test still treated the body as
raw SSE and piped it through parseSSEToGeminiResponse, which correctly
returns null for non-SSE input — failing the release-tip unit suite.

Verified the production output is exactly what the test's own assertions
expect (content 'Hello again', usage 2/3/5, finish_reason stop, 2 fetch
calls incl. the 429 retry), so this realigns the test with the real
contract rather than weakening it: 3 pass/1 fail -> 4 pass/0 fail.

changelog.d/maintenance/antigravity-nonstream-test-realign.md

@@ -0,0 +1 @@
+- Realign the Antigravity non-streaming 429-retry test with the executor's actual contract: it returns the already-converted OpenAI `chat.completion` payload, so the test asserts that payload directly instead of re-parsing it as raw SSE (which returned `null` and failed the release-tip unit suite).

tests/unit/antigravity-streaming-passthrough.test.ts

@@ -9,7 +9,6 @@ import {
   AntigravityExecutor,
   createCreditsExtractionTransform,
 } from "../../open-sse/executors/antigravity.ts";
-import { parseSSEToGeminiResponse } from "../../open-sse/handlers/sseParser/geminiResponse.ts";
 import {
   clearAntigravityVersionCache,
   seedAntigravityVersionCache,
@@ -73,11 +72,10 @@ test("AntigravityExecutor.execute auto-retries short 429 responses and collects
       credentials: { accessToken: "token", projectId: "project-1" },
       log: { debug() {}, warn() {} },
     });
-    // Non-streaming now returns raw SSE; parse it the way chatCore would.
-    const rawSSE = await result.response.text();
-    const parsed = parseSSEToGeminiResponse(rawSSE, "antigravity/gemini-2.5-flash");
-    assert.ok(parsed, "parseSSEToGeminiResponse should parse the SSE");
-    const payload = parsed as ChatCompletionPayload;
+    // Non-streaming collects the upstream SSE and returns the already-converted
+    // OpenAI chat.completion payload — no further SSE parsing on the caller side.
+    const payload = JSON.parse(await result.response.text()) as ChatCompletionPayload;
+    assert.equal(payload.object, "chat.completion");
 
     assert.equal(calls.length, 2);
     assert.equal(result.response.status, 200);