fix(artifacts): honor cancellation at the output publication boundary

src/artifacts/SafeOutputTree.ts

@@ -280,9 +280,11 @@ export class SafeOutputTree {
   }
 
   /** Sync the owned output tree and prevent further writes through this instance. */
-  async commit(): Promise<void> {
+  async commit(signal?: AbortSignal): Promise<void> {
     this.#assertWritable();
+    abortIfNeeded(signal);
     await this.#assertOwnedDirectories();
+    abortIfNeeded(signal);
     // Windows has no directory fsync; file contents are already synced in write().
     if (this.platform === "win32") {
       this.#published = true;
@@ -315,6 +317,7 @@ export class SafeOutputTree {
       );
       await output.handle.sync();
       await parent.handle.sync();
+      abortIfNeeded(signal);
       this.#published = true;
     } catch (cause: unknown) {
       sync = { kind: "failed", cause };
@@ -336,23 +339,26 @@ export class SafeOutputTree {
         closeFailure,
         this.#outputRoot,
       );
-      if (sync.kind === "failed")
-        throw ArtifactReaderFailure.withCleanup(
-          new ArtifactReaderFailure(
-            "path",
-            "Could not durably sync extraction output",
-            { cause: sync.cause },
-          ),
-          cleanup,
-        );
+      if (sync.kind === "failed") {
+        const primary = isCancellationFailure(sync.cause)
+          ? sync.cause
+          : new ArtifactReaderFailure(
+              "path",
+              "Could not durably sync extraction output",
+              { cause: sync.cause },
+            );
+        throw ArtifactReaderFailure.withCleanup(primary, cleanup);
+      }
       throw ArtifactReaderFailure.withCleanup(closeFailure, cleanup);
     }
-    if (sync.kind === "failed")
+    if (sync.kind === "failed") {
+      if (isCancellationFailure(sync.cause)) throw sync.cause;
       throw new ArtifactReaderFailure(
         "path",
         "Could not durably sync extraction output",
         { cause: sync.cause },
       );
+    }
   }
 
   /** Remove only this operation's unsealed tree and verify absence. */
@@ -590,6 +596,11 @@ const abortIfNeeded = (signal?: AbortSignal): void => {
     );
 };
 
+const isCancellationFailure = (
+  cause: unknown,
+): cause is ArtifactReaderFailure =>
+  cause instanceof ArtifactReaderFailure && cause.reason === "cancelled";
+
 const isAlreadyExists = (cause: unknown): boolean =>
   cause instanceof Error && "code" in cause && cause.code === "EEXIST";