diff --git a/maps/feature-map/runs-adapters.md b/maps/feature-map/runs-adapters.md
index 9432c9a792b..25744903964 100644
--- a/maps/feature-map/runs-adapters.md
+++ b/maps/feature-map/runs-adapters.md
@@ -75,7 +75,9 @@ mutations. Qualify a useful model task separately from saving the account.
 ### `session`
 
 For a repository project that inherits storage-plugin defaults, run a task and
-send two follow-ups. Binding the workspace must preserve the effective policy,
+send two follow-ups. Start with unset task workspace settings, then repeat with
+an explicit isolated mode or strategy. Binding must save `reuse_existing` and
+the resolved mode without changing the effective policy,
 session fingerprint, and workspace identity. An actual project-policy change
 must still reset the session and preserve the stored workspace owner. The
 [session admission regression](../../server/src/__tests__/heartbeat-session-preparation.test.ts)
diff --git a/server/src/__tests__/heartbeat-session-preparation.test.ts b/server/src/__tests__/heartbeat-session-preparation.test.ts
index 13d0544016b..2d117a6855c 100644
--- a/server/src/__tests__/heartbeat-session-preparation.test.ts
+++ b/server/src/__tests__/heartbeat-session-preparation.test.ts
@@ -112,7 +112,11 @@ describePostgres("heartbeat session preparation through adapter dispatch", () =>
     } finally { await db.delete(plugins).where(eq(plugins.id, storage.pluginId)); }
   });
 
-  it("keeps inherited repository policy stable through binding and retains the provider on policy changes", async () => {
+  it.each([
+    null,
+    { mode: "isolated_workspace" },
+    { workspaceStrategy: { type: "git_worktree", branchTemplate: "work" } },
+  ])("keeps inherited repository policy stable through binding with settings %j and retains the provider on policy changes", async (settings) => {
     const f = await seed();
     const storage = await createPluginWorkspaceFixture(db, f.companyId);
     const [plugin] = await db.select().from(plugins).where(eq(plugins.id, storage.pluginId));
@@ -121,7 +125,7 @@ describePostgres("heartbeat session preparation through adapter dispatch", () =>
     } } }).where(eq(plugins.id, storage.pluginId));
     await db.update(projects).set({ executionWorkspacePolicy: null }).where(eq(projects.id, storage.input.projectId));
     await db.update(issues).set({ projectId: storage.input.projectId, projectWorkspaceId: storage.input.projectWorkspaceId,
-      executionWorkspaceSettings: { workspaceStrategy: { type: "git_worktree", branchTemplate: "work" } },
+      executionWorkspaceSettings: settings,
     }).where(eq(issues.id, f.issueId));
     await instanceSettingsService(db).updateExperimental({ enableIsolatedWorkspaces: true, enableIsolatedWorkspacesByDefault: true });
     const cwd = await mkdtemp(join(tmpdir(), "session-provider-fixture-"));
@@ -140,6 +144,8 @@ describePostgres("heartbeat session preparation through adapter dispatch", () =>
       const first = await execute(f);
       const [bound] = await db.select().from(issues).where(eq(issues.id, f.issueId));
       expect(bound.executionWorkspaceId).toEqual(expect.any(String));
+      expect(bound.executionWorkspacePreference).toBe("reuse_existing");
+      expect(bound.executionWorkspaceSettings).toEqual({ ...settings, mode: "isolated_workspace" });
       const [workspace] = await db.select().from(executionWorkspaces).where(eq(executionWorkspaces.id, bound.executionWorkspaceId!));
       expect([...captured.values()].filter(input => input.context.issueId === f.issueId)).toHaveLength(1);
       expect(workspace).toMatchObject({ providerType: "plugin", strategyType: "git_worktree" });
diff --git a/server/src/__tests__/helpers/plugin-workspaces.ts b/server/src/__tests__/helpers/plugin-workspaces.ts
index 31cc69c1546..0ebb4af7a03 100644
--- a/server/src/__tests__/helpers/plugin-workspaces.ts
+++ b/server/src/__tests__/helpers/plugin-workspaces.ts
@@ -100,6 +100,7 @@ export async function createPluginWorkspaceFixture(
     status: "running",
   });
   const calls: any[] = [];
+  const preparedBranches = new Map<string, string | null>();
   let loseResponse = false,
     dirty = false,
     removed = false,
@@ -120,6 +121,7 @@ export async function createPluginWorkspaceFixture(
       }
       if (params.operation.kind === "prepare") {
         removed = false;
+        preparedBranches.set(params.executionWorkspaceId, params.operation.branchName ?? null);
         return {
           kind: "prepared",
           binding: {
@@ -141,7 +143,7 @@ export async function createPluginWorkspaceFixture(
         return {
           kind: "inspection",
           headSha: "a".repeat(40),
-          branchName: "work",
+          branchName: preparedBranches.get(params.executionWorkspaceId) ?? "work",
           hasDirtyTrackedFiles: dirty,
           hasUntrackedFiles: false,
           hasLocalOnlyData: false,