fix(cancellation): preserve caller abort reason in cancellation errors (#6144)

* fix(cancellation): preserve caller abort reason in cancellation errors

Several application, provider, and MCP boundaries constructed
AnalysisCancelledError, ArtifactReaderFailure, or
DetachedPgpSignatureError for an already-observed or newly-observed abort
without passing the caller's signal.reason as the error cause. The typed
result then reported cancellation with an undefined reason even though the
exact object supplied to AbortController.abort(reason) was still available.

Pass signal.reason as the cause at each producing cancellation site:
JavaScript artifact reconstruction and file abort checks, derived MCP
operation checkpoints, detached PGP verification, ASAR listing admission,
Dart AOT inspection and its provider guard, evidence-file analysis views,
binary layout and recorded crash admission, WASM inspection admission,
and the Kuna shared assembly-index wait.

Cancellation classification and cleanup behavior are unchanged.

Fixes morluto/rea#5935
Fixes morluto/rea#5944
Fixes morluto/rea#6100
Fixes morluto/rea#6101
Fixes morluto/rea#6110
Fixes morluto/rea#6113
Fixes morluto/rea#6121
Fixes morluto/rea#6131
Fixes morluto/rea#6132

* test(cancellation): assert the exact caller reason identity

Copied reasons satisfied toMatchObject, so the tests would pass even if the
caller's abort reason were replaced by a structurally equal copy. Capture the
rejection and assert the cause is the same object.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 35b247e9-c793-4b8f-979a-807c27112cf5

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 35b247e9-c793-4b8f-979a-807c27112cf5

src/application/analysisView/AnalysisViewService.test.ts

@@ -1023,27 +1023,32 @@ describe("inspectAnalysisViewWithFiles", () => {
 
   it("returns typed cancellation for a cancelled file request", async () => {
     const controller = new AbortController();
-    controller.abort();
+    const reason = Object.freeze({ requested: "view-stop" });
+    controller.abort(reason);
     const parent = analysisViewCaptureEvidence(
       environmentManifestCaptureFixture(),
     );
-    expect(
-      await inspectAnalysisViewWithFiles(
-        {
-          source: {
-            kind: "evidence-file",
-            path: await writeEvidenceFile(parent),
-          },
-          view,
+    const result = await inspectAnalysisViewWithFiles(
+      {
+        source: {
+          kind: "evidence-file",
+          path: await writeEvidenceFile(parent),
         },
-        undefined,
-        { signal: controller.signal },
-      ),
-    ).toMatchObject({ ok: false, error: { _tag: "AnalysisCancelledError" } });
+        view,
+      },
+      undefined,
+      { signal: controller.signal },
+    );
+    expect(result).toMatchObject({
+      ok: false,
+      error: { _tag: "AnalysisCancelledError" },
+    });
+    expect(result.ok ? undefined : result.error.cause).toBe(reason);
   });
 
   it("returns typed cancellation when a running file request is aborted", async () => {
     const controller = new AbortController();
+    const reason = Object.freeze({ requested: "running-view-stop" });
     const parent = analysisViewCaptureEvidence(
       environmentManifestCaptureFixture(),
     );
@@ -1054,11 +1059,13 @@ describe("inspectAnalysisViewWithFiles", () => {
       { signal: controller.signal },
     );
     // Queued before the request yields after its synchronous work, so it is seen even if the read already finished.
-    setImmediate(() => controller.abort());
-    expect(await running).toMatchObject({
+    setImmediate(() => controller.abort(reason));
+    const result = await running;
+    expect(result).toMatchObject({
       ok: false,
       error: { _tag: "AnalysisCancelledError" },
     });
+    expect(result.ok ? undefined : result.error.cause).toBe(reason);
   });
 
   it("leaves file sources to the file-aware entry point", () => {