diff --git a/server/src/__tests__/heartbeat-workspace-session.test.ts b/server/src/__tests__/heartbeat-workspace-session.test.ts
index a969382862..0495f3bd93 100644
--- a/server/src/__tests__/heartbeat-workspace-session.test.ts
+++ b/server/src/__tests__/heartbeat-workspace-session.test.ts
@@ -2092,6 +2092,57 @@ describe("effective run session config freshness", () => {
     expect(decision.reasons.join("\n")).toContain("adapter config");
   });
 
+  it("does not reset for issue comment timestamps but still resets for workspace settings", async () => {
+    const base = await buildSessionConfigMetadata({
+      workspaceConfig: {
+        requestedMode: "agent_default",
+        effectiveMode: "agent_default",
+        issueConfigRevisionAt: "2026-06-01T00:00:00.000Z",
+        issueSettings: null,
+      },
+    });
+    const commentOnly = await buildSessionConfigMetadata({
+      workspaceConfig: {
+        requestedMode: "agent_default",
+        effectiveMode: "agent_default",
+        issueConfigRevisionAt: "2026-06-01T00:05:00.000Z",
+        issueSettings: null,
+      },
+    });
+    const workspaceChanged = await buildSessionConfigMetadata({
+      workspaceConfig: {
+        requestedMode: "isolated_workspace",
+        effectiveMode: "isolated_workspace",
+        issueConfigRevisionAt: "2026-06-01T00:05:00.000Z",
+        issueSettings: { mode: "isolated_workspace" },
+      },
+    });
+
+    expect(
+      resolveTaskSessionConfigFreshness({
+        hasTaskSession: true,
+        configuredModel: "gpt-5.4-mini",
+        taskSessionParams: sessionParamsWithConfigMetadata(base),
+        configMetadata: commentOnly,
+      }),
+    ).toMatchObject({
+      reset: false,
+      changedCategories: [],
+      reasons: [],
+    });
+    expect(
+      resolveTaskSessionConfigFreshness({
+        hasTaskSession: true,
+        configuredModel: "gpt-5.4-mini",
+        taskSessionParams: sessionParamsWithConfigMetadata(base),
+        configMetadata: workspaceChanged,
+      }),
+    ).toMatchObject({
+      reset: true,
+      changedCategories: ["workspaceConfig"],
+    });
+  });
+
   it("keeps model-only compatibility as an additional reset reason", async () => {
     const base = await buildSessionConfigMetadata();
 
diff --git a/server/src/services/heartbeat.ts b/server/src/services/heartbeat.ts
index 5b3ceae2a7..b92f81358b 100644
--- a/server/src/services/heartbeat.ts
+++ b/server/src/services/heartbeat.ts
@@ -4842,6 +4842,12 @@ function buildSessionConfigCategoryValues(input: {
   agentConfigRevision: unknown;
 }) {
   const sanitizedSecretManifest = sanitizeSecretManifestForConfigFingerprint(input.secretManifest);
+  const workspaceConfig = { ...parseObject(input.workspaceConfig) };
+  // issues.updatedAt also advances for comments and status changes. Those are
+  // wake deltas, not execution-workspace configuration changes, so including
+  // the timestamp here makes every comment invalidate an otherwise reusable
+  // task session.
+  delete workspaceConfig.issueConfigRevisionAt;
   return {
     adapter: {
       adapterType: input.adapterType,
@@ -4852,7 +4858,7 @@ function buildSessionConfigCategoryValues(input: {
     modelProfile: input.modelProfile,
     instructions: input.instructions,
     issueOverrides: input.issueOverrides,
-    workspaceConfig: input.workspaceConfig,
+    workspaceConfig,
     environment: input.environment,
     envBindings: {
       environment: { env: input.environmentEnv },