diff --git a/.codearbiter/gate-events.log b/.codearbiter/gate-events.log
index c97e0bf3..6023aa83 100644
--- a/.codearbiter/gate-events.log
+++ b/.codearbiter/gate-events.log
@@ -983,3 +983,4 @@ Claude-Session: https://claude.ai/code/session_015ZDVU1BzUqnnPVHbZ397bX') stages
 [2026-07-26T13:49:34Z] REMIND [H-12] hook=post-write-edit.py | core/pysrc/_sloplib.py is governed by ADR-0011 (Multi-host support — third sibling plugin ca-codex via shared core + thin host adapters). If this change contradicts it, route to /ca:reconcile or /ca:adr — do not drift silently.
 [2026-07-26T13:49:39Z] REMIND [H-12] hook=post-write-edit.py | core/pysrc/_sloplib.py is governed by ADR-0011 (Multi-host support — third sibling plugin ca-codex via shared core + thin host adapters). If this change contradicts it, route to /ca:reconcile or /ca:adr — do not drift silently.
 [2026-07-26T13:49:48Z] REMIND [H-12] hook=post-write-edit.py | core/pysrc/_sloplib.py is governed by ADR-0011 (Multi-host support — third sibling plugin ca-codex via shared core + thin host adapters). If this change contradicts it, route to /ca:reconcile or /ca:adr — do not drift silently.
+[2026-07-26T14:10:47Z] REMIND [H-12] hook=post-write-edit.py | plugins/ca-pi/tools/test/security.test.ts is governed by ADR-0013 (Add ca-pi as a sibling governance plugin using the shared core and a thin Pi adapter). If this change contradicts it, route to /ca:reconcile or /ca:adr — do not drift silently.
diff --git a/plugins/ca-pi/tools/test/security.test.ts b/plugins/ca-pi/tools/test/security.test.ts
index 03c9159d..8b013cf0 100644
--- a/plugins/ca-pi/tools/test/security.test.ts
+++ b/plugins/ca-pi/tools/test/security.test.ts
@@ -409,6 +409,22 @@ describe("ADR-0014 adversarial promotion contract", () => {
     expect(workflow).toContain("test_pi_security.py --sarif");
   });
 
+  // #495: the two tests below each launch a cold CPython process SYNCHRONOUSLY,
+  // so the wait is billed against the test's own deadline. The script is not the
+  // slow part - `test_pi_security.py --contract-only` runs in about 70ms. What
+  // does not fit in vitest's default 5s is process creation plus interpreter
+  // startup on a loaded windows-latest runner, where both are an order of
+  // magnitude more expensive than on Linux; ubuntu and macos passed every run
+  // that windows failed. The deadline therefore has to cover a process LAUNCH,
+  // not a computation, and it is platform-aware rather than uniformly larger so
+  // a genuine hang on the fast platforms still surfaces as a hang.
+  //
+  // This is not cosmetic. `[GATE ] | [REPO] | Merge readiness` aggregates this
+  // suite, and the release preflight requires that gate green for the EXACT
+  // commit being tagged (#385) - so a flake here blocks the release lane for that
+  // SHA, and trains readers to re-run a red gate without reading it.
+  const PYTHON_SPAWN_TIMEOUT_MS = process.platform === "win32" ? 30_000 : 5_000;
+
   test("security evidence output is result-code-only even with secret-bearing ambient values", () => {
     const python = process.platform === "win32" ? "python" : "python3";
     const script = resolve(import.meta.dirname, "../../../../.github/scripts/test_pi_security.py");
@@ -429,7 +445,7 @@ describe("ADR-0014 adversarial promotion contract", () => {
     expect(JSON.stringify(report)).not.toContain("prompt");
     expect(JSON.stringify(report)).not.toContain("provider");
     expect(JSON.stringify(report)).not.toContain("stderr");
-  });
+  }, PYTHON_SPAWN_TIMEOUT_MS);
 
   test("SARIF high gate reports only a fixed code and count", async () => {
     const root = await mkdtemp(resolve(tmpdir(), "ca-pi-security-sarif-"));
@@ -463,7 +479,7 @@ describe("ADR-0014 adversarial promotion contract", () => {
     } finally {
       await rm(root, { recursive: true, force: true });
     }
-  });
+  }, PYTHON_SPAWN_TIMEOUT_MS);
 });
 
 // Issue #464 AC-2. `security-controls.md` states that tests use disposable Pi