fix(encoder): signal host interruptions for retry (#3578)

* fix(encoder): signal host interruptions for retry

* fix(encoder): cover all render interruption paths

* fix(encoder): classify HDR pre-extraction drains

packages/engine/src/utils/runFfmpeg.test.ts

@@ -2,7 +2,65 @@ import { EventEmitter } from "node:events";
 import { resolve } from "node:path";
 import { afterEach, describe, expect, it, vi } from "vitest";
 
-import { formatFfmpegError } from "./runFfmpeg.js";
+import { formatFfmpegError, isExternalFfmpegInterruption } from "./runFfmpeg.js";
+
+describe("isExternalFfmpegInterruption", () => {
+  const base = {
+    exitCode: 255,
+    signal: null,
+    stderr: "",
+    terminationReason: "exit" as const,
+  };
+
+  it("recognizes a direct external termination signal", () => {
+    expect(isExternalFfmpegInterruption({ ...base, exitCode: null, signal: "SIGTERM" })).toBe(true);
+  });
+
+  it("does not broaden the retry signal to SIGKILL", () => {
+    expect(isExternalFfmpegInterruption({ ...base, exitCode: null, signal: "SIGKILL" })).toBe(
+      false,
+    );
+  });
+
+  it("recognizes ffmpeg's handled SIGTERM exit-255 signature", () => {
+    expect(
+      isExternalFfmpegInterruption({
+        ...base,
+        stderr: "frame= 42\nExiting normally, received signal 15.\n",
+      }),
+    ).toBe(true);
+  });
+
+  it("does not classify an ordinary exit 255", () => {
+    expect(isExternalFfmpegInterruption({ ...base, stderr: "Encoder initialization failed" })).toBe(
+      false,
+    );
+  });
+
+  it("requires exit 255 when classification relies on ffmpeg stderr", () => {
+    expect(
+      isExternalFfmpegInterruption({
+        ...base,
+        exitCode: 1,
+        stderr: "Exiting normally, received signal 15.",
+      }),
+    ).toBe(false);
+  });
+
+  it.each(["abort", "deadline", "inactivity"] as const)(
+    "keeps a managed %s termination non-retryable",
+    (terminationReason) => {
+      expect(
+        isExternalFfmpegInterruption({
+          ...base,
+          signal: "SIGTERM",
+          stderr: "Exiting normally, received signal 15.",
+          terminationReason,
+        }),
+      ).toBe(false);
+    },
+  );
+});
 
 describe("formatFfmpegError", () => {
   const originalPlatform = process.platform;