diff --git a/doc/sandbox-work-folders.md b/doc/sandbox-work-folders.md
index 771e888586..3eedba2e4a 100644
--- a/doc/sandbox-work-folders.md
+++ b/doc/sandbox-work-folders.md
@@ -327,3 +327,10 @@ as incomplete. Active native turns keep their existing restart/reattach behavior
 Local and SSH session shutdown behavior is unchanged. A hard process kill cannot
 guarantee a provider-session checkpoint; scoped files and repository durability
 remain limited to the last successfully published work-folder checkpoint.
+
+Deployments must allow enough graceful shutdown time for that drain and other
+server cleanup. On Railway, configure at least 60 seconds of draining time for
+the service before testing an app redeployment; the platform default is zero.
+This is a deployment prerequisite, not a fleet-default promotion. When upgrading
+from a release without the idle-session drain, park warm native sessions and
+verify their completed harness checkpoints before stopping the old app.
diff --git a/server/src/__tests__/server-startup-feedback-export.test.ts b/server/src/__tests__/server-startup-feedback-export.test.ts
index c8ff994b11..5702743ac9 100644
--- a/server/src/__tests__/server-startup-feedback-export.test.ts
+++ b/server/src/__tests__/server-startup-feedback-export.test.ts
@@ -345,6 +345,12 @@ vi.mock("../services/question-response-delivery.js", () => ({
   })),
 }));
 
+vi.mock("../services/native-runtime/native-session-executor.js", () => ({
+  closeIdleSandboxNativeSessionsForShutdown: vi.fn(async () => ({
+    closed: 0, busy: 0, failed: 0,
+  })),
+}));
+
 vi.mock("../services/native-runtime/native-question-bridge.js", () => ({
   deliverNativeQuestionResponse: vi.fn(async () => "not_native"),
   nativeQuestionCancellationIdentity: vi.fn(() => null),
diff --git a/server/src/__tests__/workspace-runtime.test.ts b/server/src/__tests__/workspace-runtime.test.ts
index bc344b63ab..d6e96c6058 100644
--- a/server/src/__tests__/workspace-runtime.test.ts
+++ b/server/src/__tests__/workspace-runtime.test.ts
@@ -6510,6 +6510,7 @@ describeEmbeddedPostgres("workspace runtime service control persistence", () =>
     const executionWorkspaceId = randomUUID();
     const provisionMarkerPath = path.join(workspaceRoot, "runtime-provisioning.marker");
     const markerPath = path.join(workspaceRoot, "runtime-spawned.marker");
+    const readyMarkerPath = path.join(workspaceRoot, "runtime-ready.marker");
     const provisionScript = [
       `require("node:fs").writeFileSync(${JSON.stringify(provisionMarkerPath)}, "provisioning");`,
       "setTimeout(() => {}, 1200);",
@@ -6518,11 +6519,13 @@ describeEmbeddedPostgres("workspace runtime service control persistence", () =>
       `${JSON.stringify(process.execPath)} -e ${JSON.stringify(provisionScript)}`;
     const serverScript = [
       `require("node:fs").writeFileSync(${JSON.stringify(markerPath)}, "spawned");`,
-      "setTimeout(() => {",
+      "const ready = setInterval(() => {",
+      `  if (!require("node:fs").existsSync(${JSON.stringify(readyMarkerPath)})) return;`,
+      "  clearInterval(ready);",
       "  require(\"node:http\")",
       "    .createServer((_req, res) => { res.end(\"ok\"); })",
       "    .listen(Number(process.env.PORT), \"127.0.0.1\");",
-      "}, 100);",
+      "}, 10);",
       "setInterval(() => {}, 1000);",
     ].join(" ");
     const command = `${JSON.stringify(process.execPath)} -e ${JSON.stringify(serverScript)}`;
@@ -6589,7 +6592,9 @@ describeEmbeddedPostgres("workspace runtime service control persistence", () =>
           .from(workspaceRuntimeServices)
           .where(eq(workspaceRuntimeServices.executionWorkspaceId, executionWorkspaceId))
           .then((rows) => rows[0] ?? null);
-        if (row?.status === status) return row;
+        if (row?.status === status && (status !== "starting" || row.providerRef !== null)) {
+          return row;
+        }
         await new Promise((resolve) => setTimeout(resolve, 25));
       }
       throw new Error(`Timed out waiting for persisted runtime service status ${status}`);
@@ -6670,6 +6675,10 @@ describeEmbeddedPostgres("workspace runtime service control persistence", () =>
       expect(startingRow.providerRef).toMatch(/^\d+$/);
       expect(startingRow.port).toEqual(expect.any(Number));
 
+      // A process marker can arrive before its PID is persisted. Hold readiness
+      // until the complete starting row has been observed, rather than racing a
+      // fixed delay on a busy test runner.
+      await fs.writeFile(readyMarkerPath, "ready");
       const services = await startPromise;
       expect(services).toHaveLength(1);
       expect(services[0]).toMatchObject({