fix(desktop): startup crash reports capture stdout too, not just stderr

apps/desktop/src/app/DesktopCrashReport.ts

@@ -39,7 +39,7 @@ const bundledPosthogHost =
     : "https://us.i.posthog.com";
 
 const ANONYMOUS_ID_FILE_NAME = "anonymous-id";
-const STDERR_TAIL_MAX_CHARS = 2_000;
+const OUTPUT_TAIL_MAX_CHARS = 2_000;
 
 // Values following credential-shaped labels are cut before anything leaves
 // the machine. Boot-phase stderr should never contain these, but a config
@@ -56,7 +56,8 @@ export interface DesktopStartupFailureReport {
   readonly attempts: number;
   readonly lastExitCode: Option.Option<number>;
   readonly lastReason: string;
-  readonly stderrTail: string;
+  /** Interleaved stdout+stderr tail; the server logs fatal causes on stdout. */
+  readonly outputTail: string;
 }
 
 export interface DesktopCrashReportShape {
@@ -92,7 +93,7 @@ export function scrubUserPaths(text: string, homeDirectory: string): string {
 }
 
 /** Keeps the end of the captured stderr, where the fatal error lands. */
-export function truncateTail(text: string, maxChars: number = STDERR_TAIL_MAX_CHARS): string {
+export function truncateTail(text: string, maxChars: number = OUTPUT_TAIL_MAX_CHARS): string {
   return text.length <= maxChars ? text : text.slice(text.length - maxChars);
 }
 
@@ -187,7 +188,7 @@ const makeDesktopCrashReport = Effect.gen(function* () {
               attempts: report.attempts,
               exitCode: Option.getOrNull(report.lastExitCode),
               reason: scrub(report.lastReason),
-              stderrTail: scrub(truncateTail(report.stderrTail)),
+              outputTail: scrub(truncateTail(report.outputTail)),
             },
             timestamp: new Date().toISOString(),
           },

apps/desktop/src/backend/DesktopBackendManager.test.ts

@@ -587,7 +587,13 @@ describe("DesktopBackendManager", () => {
               const close = Deferred.succeed(closed, void 0).pipe(Effect.asVoid);
               yield* Scope.addFinalizer(scope, close);
               return makeProcess({
-                stderr: Stream.make(new TextEncoder().encode("EADDRINUSE: port already bound\n")),
+                // The fatal cause lands on stdout, like the server's Effect
+                // logger; stderr carries a secondary line. Both must reach
+                // the crash-report tail.
+                stdout: Stream.make(
+                  new TextEncoder().encode("[FATAL] EADDRINUSE: port already bound\n"),
+                ),
+                stderr: Stream.make(new TextEncoder().encode("node exited\n")),
                 exitCode: Deferred.await(closed).pipe(Effect.as(ChildProcessSpawner.ExitCode(143))),
                 kill: () => close,
               });
@@ -615,7 +621,8 @@ describe("DesktopBackendManager", () => {
           assert.equal(report.failureKind, "readiness-timeout");
           assert.equal(report.attempts, 1);
           assert.include(report.lastReason, "Timed out");
-          assert.include(report.stderrTail, "EADDRINUSE");
+          assert.include(report.outputTail, "EADDRINUSE");
+          assert.include(report.outputTail, "node exited");
 
           // The unresponsive process was killed and nothing respawns.
           yield* TestClock.adjust(Duration.seconds(30));

apps/desktop/src/backend/DesktopBackendManager.ts

@@ -40,8 +40,8 @@ const MAX_RESTART_DELAY = Duration.seconds(10);
 // session, restarts stay unbounded: the window exists, so a crash there is
 // not an invisible wedge.
 const MAX_STARTUP_ATTEMPTS = 3;
-// Cap on the retained stderr needed for a useful crash report.
-const STDERR_TAIL_MAX_CHARS = 8_192;
+// Cap on the retained stdout+stderr needed for a useful crash report.
+const OUTPUT_TAIL_MAX_CHARS = 8_192;
 // How long a finished process's output drains may lag its exit.
 const DRAIN_FLUSH_TIMEOUT = Duration.seconds(1);
 const DEFAULT_BACKEND_READINESS_TIMEOUT = Duration.minutes(1);
@@ -419,7 +419,7 @@ const makeDesktopBackendManager = Effect.fn("makeDesktopBackendManager")(functio
               attempts: latest.restartAttempt + 1,
               lastExitCode: Option.none(),
               lastReason: reason,
-              stderrTail: "",
+              outputTail: "",
             });
             return;
           }
@@ -428,10 +428,14 @@ const makeDesktopBackendManager = Effect.fn("makeDesktopBackendManager")(functio
         }
 
         const runScope = yield* Scope.make("sequential");
-        // Per-run crash-report inputs: the stderr tail carries the fatal
+        // Per-run crash-report inputs: the output tail carries the fatal
         // error when the process dies, the timeout marker reroutes a
-        // killed-for-unresponsiveness exit away from the restart path.
-        const stderrTailRef = yield* Ref.make("");
+        // killed-for-unresponsiveness exit away from the restart path. Both
+        // streams feed the tail — the server's Effect logger reports fatal
+        // causes on stdout, and field crash reports came back empty when
+        // only stderr was kept.
+        const outputTailRef = yield* Ref.make("");
+        const stdoutDecoder = new TextDecoder();
         const stderrDecoder = new TextDecoder();
         const readinessTimeoutRef = yield* Ref.make(Option.none<BackendTimeoutError>());
         const runId = yield* Ref.modify(state, (latest) => [
@@ -526,7 +530,7 @@ const makeDesktopBackendManager = Effect.fn("makeDesktopBackendManager")(functio
               }));
               // Let buffered output land in the tail before reading it.
               yield* flushOutput;
-              const stderrTail = yield* Ref.get(stderrTailRef);
+              const outputTail = yield* Ref.get(outputTailRef);
               yield* triggerStartupFailure({
                 failureKind: Option.isSome(readinessTimeout) ? "readiness-timeout" : "process-exit",
                 attempts: nextState.restartAttempt + 1,
@@ -535,7 +539,7 @@ const makeDesktopBackendManager = Effect.fn("makeDesktopBackendManager")(functio
                   onNone: () => reason,
                   onSome: (timeout) => timeout.message,
                 }),
-                stderrTail,
+                outputTail,
               });
             }),
           );
@@ -607,18 +611,17 @@ const makeDesktopBackendManager = Effect.fn("makeDesktopBackendManager")(functio
               }
             }),
           onOutput: (streamName, chunk) =>
-            streamName === "stderr"
-              ? backendOutputLog.writeOutputChunk(streamName, chunk).pipe(
-                  Effect.andThen(
-                    Ref.update(stderrTailRef, (tail) => {
-                      const appended = tail + stderrDecoder.decode(chunk, { stream: true });
-                      return appended.length <= STDERR_TAIL_MAX_CHARS
-                        ? appended
-                        : appended.slice(appended.length - STDERR_TAIL_MAX_CHARS);
-                    }),
-                  ),
-                )
-              : backendOutputLog.writeOutputChunk(streamName, chunk),
+            backendOutputLog.writeOutputChunk(streamName, chunk).pipe(
+              Effect.andThen(
+                Ref.update(outputTailRef, (tail) => {
+                  const decoder = streamName === "stderr" ? stderrDecoder : stdoutDecoder;
+                  const appended = tail + decoder.decode(chunk, { stream: true });
+                  return appended.length <= OUTPUT_TAIL_MAX_CHARS
+                    ? appended
+                    : appended.slice(appended.length - OUTPUT_TAIL_MAX_CHARS);
+                }),
+              ),
+            ),
         }).pipe(
           Effect.provideService(ChildProcessSpawner.ChildProcessSpawner, spawner),
           Effect.provideService(HttpClient.HttpClient, httpClient),