diff --git a/packages/gittensory-engine/src/miner/cli-subprocess-driver.ts b/packages/gittensory-engine/src/miner/cli-subprocess-driver.ts
index 3b58edfa6c..65e5d35000 100644
--- a/packages/gittensory-engine/src/miner/cli-subprocess-driver.ts
+++ b/packages/gittensory-engine/src/miner/cli-subprocess-driver.ts
@@ -24,8 +24,20 @@ export type CliSubprocessSpawnFn = (
     cwd: string;
     env: Record<string, string | undefined>;
     timeoutMs: number;
+    // Optional fast-fail deadline, mirrors src/selfhost/ai.ts's SpawnFn (#4994/#5053): a real spawn implementation
+    // starts this timer at process start and clears it the instant any stdout data arrives, so it only fires when
+    // the CLI has produced ZERO stdout by this deadline — a distinct, earlier signal than the full `timeoutMs`.
+    firstOutputTimeoutMs?: number;
   },
-) => Promise<{ stdout: string; code: number | null; stderr?: string; timedOut?: boolean }>;
+) => Promise<{
+  stdout: string;
+  code: number | null;
+  stderr?: string;
+  timedOut?: boolean;
+  // Set alongside `timedOut` only when the kill was the first-output deadline, not the full `timeoutMs` — lets the
+  // driver report a distinct "stalled" error instead of conflating it with a genuine full timeout.
+  stalledNoOutput?: boolean;
+}>;
 
 export type CliSubprocessDriverOptions = {
   /** The coding-agent CLI to spawn (e.g. "claude" or "codex"). */
@@ -34,6 +46,12 @@ export type CliSubprocessDriverOptions = {
   spawn: CliSubprocessSpawnFn;
   /** Per-run wall-clock budget handed to the spawn. Default: 120000ms. */
   timeoutMs?: number;
+  /** Optional fast-fail deadline (#4994/#5053): killed early and reported distinctly ("stalled", not a generic
+   *  timeout) if the subprocess produces zero stdout before this elapses. Mirrors src/selfhost/ai.ts's
+   *  `firstOutputTimeoutMs`/`resolveClaudeFirstOutputTimeoutMs` pattern, built after a naive single-timeout design
+   *  caused a real production outage against these same claude/codex binaries. Opt-in and backward compatible:
+   *  omitting it leaves behavior exactly as it was before this option existed. */
+  firstOutputTimeoutMs?: number;
   /** Parent env to allowlist from. Default: `{}` (a real caller passes `process.env`; the default stays pure). */
   parentEnv?: Record<string, string | undefined>;
   /** Extra env overlaid on the allowlisted parent (e.g. an auth value the CLI reads). */
@@ -98,9 +116,25 @@ export function createCliSubprocessCodingAgentDriver(options: CliSubprocessDrive
         cwd: task.workingDirectory,
         env,
         timeoutMs,
+        ...(options.firstOutputTimeoutMs !== undefined
+          ? { firstOutputTimeoutMs: options.firstOutputTimeoutMs }
+          : {}),
       });
       const transcript = redactSecrets(spawned.stdout, knownSecrets).slice(0, MAX_TRANSCRIPT_CHARS);
 
+      if (spawned.timedOut && spawned.stalledNoOutput) {
+        // Fast-fail path (#4994/#5053): killed at firstOutputTimeoutMs, well before the full timeoutMs, because
+        // stdout produced no bytes at all. A distinct error (never reusing `${command}_timeout_...`) so this
+        // stall is separately countable in logs/Sentry from a genuine full timeout where the process was at
+        // least emitting output before it was killed.
+        return {
+          ok: false,
+          changedFiles: [],
+          summary: `${options.command} stalled with no stdout within ${options.firstOutputTimeoutMs}ms`,
+          transcript,
+          error: `${options.command}_stalled_no_output`,
+        };
+      }
       if (spawned.timedOut) {
         return {
           ok: false,
diff --git a/test/unit/cli-subprocess-driver.test.ts b/test/unit/cli-subprocess-driver.test.ts
index 2ddebb1f54..55f28611dc 100644
--- a/test/unit/cli-subprocess-driver.test.ts
+++ b/test/unit/cli-subprocess-driver.test.ts
@@ -115,4 +115,59 @@ describe("createCliSubprocessCodingAgentDriver (#4266)", () => {
     expect(result.transcript).toBe("used [redacted] to auth");
     expect(calls[0]?.args).toEqual(["run", "attempt-1"]);
   });
+
+  describe("two-tier stalled-output fast-fail timeout (#4994/#5053)", () => {
+    it("reports a distinct stalled error when the subprocess produces zero stdout within firstOutputTimeoutMs", async () => {
+      const { spawn, calls } = fakeSpawn({ stdout: "", code: null, timedOut: true, stalledNoOutput: true });
+      const driver = createCliSubprocessCodingAgentDriver({
+        command: "claude",
+        spawn,
+        timeoutMs: 120_000,
+        firstOutputTimeoutMs: 5000,
+      });
+      const result = await driver.run(TASK);
+      expect(result.ok).toBe(false);
+      expect(result.error).toBe("claude_stalled_no_output");
+      expect(result.summary).toBe("claude stalled with no stdout within 5000ms");
+      expect(calls[0]?.opts.firstOutputTimeoutMs).toBe(5000);
+    });
+
+    it("is NOT killed early by the first-output timer when the subprocess produces output before firstOutputTimeoutMs (invariant: live output is never mistaken for a stall)", async () => {
+      const { spawn } = fakeSpawn({ stdout: "produced some output then finished", code: 0 });
+      const driver = createCliSubprocessCodingAgentDriver({ command: "claude", spawn, firstOutputTimeoutMs: 1000 });
+      const result = await driver.run(TASK);
+      expect(result.ok).toBe(true);
+      expect(result.summary).toBe("claude completed for attempt-1");
+    });
+
+    it("preserves the existing full-timeout behavior unchanged when output arrived but the process never exited (#4994/#5053 regression guard)", async () => {
+      // stalledNoOutput is absent -- stdout arrived, so only the full timeoutMs governs, same as before this
+      // feature existed.
+      const { spawn } = fakeSpawn({ stdout: "partial", code: null, timedOut: true });
+      const driver = createCliSubprocessCodingAgentDriver({
+        command: "codex",
+        spawn,
+        timeoutMs: 5000,
+        firstOutputTimeoutMs: 1000,
+      });
+      const result = await driver.run(TASK);
+      expect(result.ok).toBe(false);
+      expect(result.error).toBe("codex_timeout_5000ms");
+      expect(result.summary).toBe("codex timed out after 5000ms");
+    });
+
+    it("does not forward firstOutputTimeoutMs to spawn when omitted (opt-in, backward compatible)", async () => {
+      const { spawn, calls } = fakeSpawn({ stdout: "done", code: 0 });
+      const driver = createCliSubprocessCodingAgentDriver({ command: "claude", spawn });
+      await driver.run(TASK);
+      expect("firstOutputTimeoutMs" in (calls[0]?.opts ?? {})).toBe(false);
+    });
+
+    it("invariant: the driver's result never carries any field beyond the CodingAgentDriverResult contract (no attempt/governor state)", async () => {
+      const { spawn } = fakeSpawn({ stdout: "", code: null, timedOut: true, stalledNoOutput: true });
+      const driver = createCliSubprocessCodingAgentDriver({ command: "claude", spawn, firstOutputTimeoutMs: 500 });
+      const result = await driver.run(TASK);
+      expect(Object.keys(result).sort()).toEqual(["changedFiles", "error", "ok", "summary", "transcript"]);
+    });
+  });
 });