diff --git a/doc/plans/2026-10-06-default-agent-runner.md b/doc/plans/2026-10-06-default-agent-runner.md
index 65583ee507a..d64f4c44eb8 100644
--- a/doc/plans/2026-10-06-default-agent-runner.md
+++ b/doc/plans/2026-10-06-default-agent-runner.md
@@ -2,6 +2,24 @@
 
 Updated 2026-10-12.
 
+## Fixture closure checkpoint
+
+The runtime prerequisite advances to `093b97aa12` with 54 files. The Codex
+review remains 99 files. Existing managed fixtures now run the saved environment
+probe before native-generation Codex creation and inspect server defaults only
+for automatic requests. The owned setup probe lease joins the existing runtime
+estimator, with unrelated leases excluded from task attribution. The fixture
+contract records one setup lease per eligible cell, zero provider turns, zero
+retries, a 330-second HTTP deadline and a 10-second platform command deadline.
+Archive/release, expiry and failure-cost holds remain unchanged.
+
+Both worktrees pass 36 existing fixture/billing controls and canonical E2E
+no-emit. Existing catalog/report controls pass 46 cases, and core compatibility
+discovery succeeds. Affected adapter discovery/setup routes pass 69 controls.
+Unknown sandbox facts now expect Legacy; measured GNU2.39 ARM64 expects native.
+All checks use fixtures, not paid provider proof. Exact-head hosted CI/review and
+real managed onboarding/task/follow-up remain pending. No merge has occurred.
+
 ## Corrective source checkpoint: ready for fresh CI and review
 
 Runtime prerequisite source is `cf19e086ae4a0142c8b4314771c55f73b294805b`
diff --git a/server/src/__tests__/adapter-routes.test.ts b/server/src/__tests__/adapter-routes.test.ts
index b042705a9b9..9ccc123a859 100644
--- a/server/src/__tests__/adapter-routes.test.ts
+++ b/server/src/__tests__/adapter-routes.test.ts
@@ -173,6 +173,7 @@ describe("adapter routes", () => {
     [{ driver: "ssh", platform: "linux", architecture: "arm64" }, "paperclip"],
     [{ driver: "ssh", platform: "linux", architecture: "arm" }, "legacy"],
     [{ driver: "local", platform: "win32", architecture: "x64" }, "legacy"],
+    [{ driver: "sandbox", platform: "linux", architecture: "arm64", libc: "glibc", glibcVersion: "2.39" }, "paperclip"],
   ])("projects the selected environment once for the whole adapter inventory (%s)", async (target, defaultRunner) => {
     const resolveRunnerTarget = vi.fn(async () => target);
     const response = await request(createApp({}, { resolveRunnerTarget })).get("/api/adapters?companyId=company-1&environmentId=selected");
@@ -187,7 +188,7 @@ describe("adapter routes", () => {
     const response = await request(createApp({}, { resolveRunnerTarget })).get("/api/adapters?companyId=company-1");
     expect(response.status).toBe(200);
     expect(resolveRunnerTarget).toHaveBeenCalledExactlyOnceWith("company-1", undefined);
-    expect(response.body.find((adapter: any) => adapter.type === "codex_local")).toMatchObject({ defaultRunner: "paperclip" });
+    expect(response.body.find((adapter: any) => adapter.type === "codex_local")).toMatchObject({ defaultRunner: "legacy" });
   });
 
   it("keeps unscoped inventory independent of company target discovery", async () => {