diff --git a/docs/tool-design.md b/docs/tool-design.md
index ea54ba4e3b..26e5e40098 100644
--- a/docs/tool-design.md
+++ b/docs/tool-design.md
@@ -151,6 +151,11 @@ providers need not expose identical state machines.
   waits for owned cleanup and retains its failure. Provider closure is distinct
   from caller cancellation. Retained cleanup capabilities block replacement;
   derive readiness from the current startup's completion and live connection.
+- Session `cleanup_pending` includes retained blockers from external mutation
+  owners until those owners confirm release. Closing the analysis session does
+  not release resources owned by an external debugger. Reading a selected
+  analysis snapshot is part of `open_binary`; cancellation keeps that operation
+  and the caller's reason through the shared JSON reader.
 - For cancellable observations, carry cancellation through result consumption
   and awaited cleanup. Before returning success, check the signal after the
   last awaited finalization step.
diff --git a/src/application/JsonFiles.ts b/src/application/JsonFiles.ts
index 8476eff44f..a96b06ee69 100644
--- a/src/application/JsonFiles.ts
+++ b/src/application/JsonFiles.ts
@@ -103,6 +103,7 @@ export const readJsonObjectMembersFile = (
   scans: readonly ReadonlyMap<string, JsonObjectMemberReader>[],
   signal?: AbortSignal,
   resources?: ArtifactResourceScope,
+  operation = "read_evidence_file",
 ): Promise<
   Result<
     void,
@@ -112,14 +113,9 @@ export const readJsonObjectMembersFile = (
   readJsonFileInput(
     path,
     (selected) =>
-      readJsonObjectFile(
-        selected,
-        "read_evidence_file",
-        scans,
-        signal,
-        resources,
-      ),
+      readJsonObjectFile(selected, operation, scans, signal, resources),
     signal,
+    operation,
   );
 
 type JsonFileReadFailure =
diff --git a/src/application/binary/AnalysisSnapshotFiles.ts b/src/application/binary/AnalysisSnapshotFiles.ts
index 4ff1b9709e..af1842af35 100644
--- a/src/application/binary/AnalysisSnapshotFiles.ts
+++ b/src/application/binary/AnalysisSnapshotFiles.ts
@@ -19,6 +19,7 @@ import type { JsonObjectMemberReader } from "../JsonInputFile.js";
 import type { ArtifactResourceScope } from "../../artifacts/ArtifactResourceScope.js";
 
 type SnapshotFailure = EvidenceFileError | EvidenceIntegrityError;
+const READ_OPERATION = "open_binary";
 
 /** Read and validate an analysis snapshot from the caller's path. */
 export const readAnalysisSnapshot = async (
@@ -63,6 +64,7 @@ export const readAnalysisSnapshot = async (
       ],
       signal,
       resources,
+      READ_OPERATION,
     );
     if (!loaded.ok) return loaded;
     signal?.throwIfAborted();
@@ -77,7 +79,9 @@ export const readAnalysisSnapshot = async (
     return ok(snapshot);
   } catch (cause: unknown) {
     if (signal?.aborted === true)
-      return err(new AnalysisCancelledError("read_evidence_file", { cause }));
+      return err(
+        new AnalysisCancelledError(READ_OPERATION, { cause: signal.reason }),
+      );
     return err(
       new EvidenceIntegrityError(snapshotValidationMessage(cause), { cause }),
     );
diff --git a/src/application/binary/BinarySession.ts b/src/application/binary/BinarySession.ts
index 340606c27b..9992e87d58 100644
--- a/src/application/binary/BinarySession.ts
+++ b/src/application/binary/BinarySession.ts
@@ -1033,6 +1033,7 @@ export class BinarySession
       requestActivitySnapshots: client?.requestActivitySnapshots?.() ?? [],
       providerOperationHealth: client?.operationHealthSnapshot?.() ?? null,
       cleanupPending:
+        this.#externalMutationCleanupFailure?.cleanupIncomplete === true ||
         this.#pendingCleanup !== undefined ||
         this.#pendingBundleResourceCleanup.length > 0 ||
         this.hasPendingFileResources ||
diff --git a/tests/boundary/filesystem/analysisSnapshot.test.ts b/tests/boundary/filesystem/analysisSnapshot.test.ts
index 11701e519c..407751b8c2 100644
--- a/tests/boundary/filesystem/analysisSnapshot.test.ts
+++ b/tests/boundary/filesystem/analysisSnapshot.test.ts
@@ -276,6 +276,7 @@ describe("analysis snapshot member decoding", () => {
       `${" ".repeat(9 * 1024 * 1024)}${JSON.stringify(snapshot)}`,
     );
     const controller = new AbortController();
+    const reason = { request: "cancel snapshot import" };
     const reads = await holdFirstFileRead(path);
     onTestFinished(() => {
       controller.abort();
@@ -283,12 +284,16 @@ describe("analysis snapshot member decoding", () => {
     });
     const pending = readAnalysisSnapshot(path, controller.signal);
     await reads.firstRead;
-    controller.abort();
+    controller.abort(reason);
     reads.release();
     try {
       expect(await pending).toMatchObject({
         ok: false,
-        error: { _tag: "AnalysisCancelledError" },
+        error: {
+          _tag: "AnalysisCancelledError",
+          operation: "open_binary",
+          cause: reason,
+        },
       });
       expect(reads.readCount).toBe(1);
     } finally {
diff --git a/tests/composition/analysis-sessions/binarySession.test.ts b/tests/composition/analysis-sessions/binarySession.test.ts
index 0e4ab9d80e..c0dfe6cced 100644
--- a/tests/composition/analysis-sessions/binarySession.test.ts
+++ b/tests/composition/analysis-sessions/binarySession.test.ts
@@ -11,6 +11,7 @@ import { createAnalysisProfile } from "../../../src/domain/analysisProfile.js";
 import { HopperStartError } from "../../../src/domain/hopperErrors.js";
 import { ProviderAdapterError } from "../../../src/domain/providerAdapterError.js";
 import { ProviderCleanupError } from "../../../src/domain/providerCleanupError.js";
+import { AnalysisCleanupLease } from "../../../src/artifacts/AnalysisCleanupLease.js";
 import { err, ok as resultOk } from "../../../src/domain/result.js";
 import { createEvidenceBundle } from "../../../src/domain/evidenceBundle.js";
 import { createEvidence } from "../../../src/domain/evidence.js";
@@ -262,6 +263,41 @@ it("leaves analysis unbound when a command returns before its writer finishes",
   await session.close();
 });
 
+it("reports an external cleanup blocker until its exact owner confirms release", async () => {
+  const [target] = await createBinarySessionTargets();
+  const session = createTestBinarySession(createCacheProvider([]));
+  const failure = new ProviderCleanupError(
+    "external-debugger",
+    ["external-run"],
+    {},
+  );
+  let released = false;
+  const lease = new AnalysisCleanupLease(async () => {
+    released = true;
+  }, ["external-run"]);
+  lease.bindCleanupError(failure);
+  try {
+    expect(await session.status()).toMatchObject({ cleanup_pending: false });
+    await session.withAdmittedExternalMutation(
+      target,
+      undefined,
+      async () => err(failure),
+      (_value, error) => error,
+    );
+    expect(await session.status()).toMatchObject({ cleanup_pending: true });
+    expect(await session.open(target)).toEqual(err(failure));
+    await session.close();
+    expect(released).toBe(false);
+    expect(await session.status()).toMatchObject({ cleanup_pending: true });
+    await lease.release();
+    expect(await session.status()).toMatchObject({ cleanup_pending: false });
+    expect((await session.open(target)).ok).toBe(true);
+  } finally {
+    await lease.release();
+    await session.close();
+  }
+});
+
 it("retires analysis when an external mutation uses a hard link", async () => {
   const [target] = await createBinarySessionTargets();
   const alias = join(dirname(target), "hard-link-alias.hop");