fix(cancellation): retain caller reasons across digest and startup

src/application/reverse/ReverseEngineeringService.ts

@@ -1057,7 +1057,11 @@ export const digestFile = async (
       remainingMs,
     );
     const abort = (): void => {
-      stream.destroy(new AnalysisCancelledError("artifact_digest"));
+      stream.destroy(
+        new AnalysisCancelledError("artifact_digest", {
+          cause: signal?.reason,
+        }),
+      );
     };
     const cleanup = (): void => {
       clearTimeout(timer);
@@ -1066,7 +1070,11 @@ export const digestFile = async (
     if (signal?.aborted) {
       cleanup();
       stream.destroy();
-      rejectDigest(new AnalysisCancelledError("artifact_digest"));
+      rejectDigest(
+        new AnalysisCancelledError("artifact_digest", {
+          cause: signal.reason,
+        }),
+      );
       return;
     }
     signal?.addEventListener("abort", abort, { once: true });
@@ -1139,7 +1147,9 @@ const statWithDeadline = (
   timeoutMs: number,
 ): Promise<Stats> => {
   if (signal?.aborted)
-    return Promise.reject(new AnalysisCancelledError("artifact_digest"));
+    return Promise.reject(
+      new AnalysisCancelledError("artifact_digest", { cause: signal.reason }),
+    );
   return new Promise<Stats>((resolveStat, rejectStat) => {
     let settled = false;
     const finish = (outcome: Result<Stats, unknown>): void => {
@@ -1151,7 +1161,13 @@ const statWithDeadline = (
       else rejectStat(outcome.error);
     };
     const abort = (): void =>
-      finish(err(new AnalysisCancelledError("artifact_digest")));
+      finish(
+        err(
+          new AnalysisCancelledError("artifact_digest", {
+            cause: signal?.reason,
+          }),
+        ),
+      );
     const timer = setTimeout(
       () =>
         finish(