feat(http-recorder): default mode to "auto" (#26719)

packages/http-recorder/test/record-replay.test.ts

@@ -301,6 +301,59 @@ describe("http-recorder", () => {
     )
   })
 
+  test("auto mode replays when the cassette exists", async () => {
+    const directory = fs.mkdtempSync(path.join(os.tmpdir(), "http-recorder-auto-"))
+    const cassettePath = path.join(directory, "auto-replay.json")
+    fs.writeFileSync(
+      cassettePath,
+      formatCassette(
+        cassetteFor(
+          "auto-replay",
+          [
+            {
+              transport: "http",
+              request: {
+                method: "POST",
+                url: "https://example.test/echo",
+                headers: { "content-type": "application/json" },
+                body: JSON.stringify({ step: 1 }),
+              },
+              response: { status: 200, headers: { "content-type": "application/json" }, body: '{"reply":"hi"}' },
+            },
+          ],
+          undefined,
+        ),
+      ),
+    )
+
+    const result = await runWith(
+      "auto-replay",
+      { directory, mode: "auto" },
+      post("https://example.test/echo", { step: 1 }),
+    )
+    expect(result).toBe('{"reply":"hi"}')
+  })
+
+  test("auto mode forces replay when CI=true even if cassette is missing", async () => {
+    const directory = fs.mkdtempSync(path.join(os.tmpdir(), "http-recorder-auto-ci-"))
+    const previous = process.env.CI
+    process.env.CI = "true"
+    try {
+      const exit = await Effect.runPromise(
+        Effect.exit(
+          post("https://example.test/echo", { step: 1 }).pipe(
+            Effect.provide(HttpRecorder.cassetteLayer("missing-cassette", { directory, mode: "auto" })),
+          ),
+        ),
+      )
+      expect(Exit.isFailure(exit)).toBe(true)
+      expect(failureText(exit)).toContain('Fixture "missing-cassette" not found')
+    } finally {
+      if (previous === undefined) delete process.env.CI
+      else process.env.CI = previous
+    }
+  })
+
   test("mismatch diagnostics show closest redacted request differences", async () => {
     await run(
       Effect.gen(function* () {