diff --git a/apps/server/src/provider/Drivers/AntigravityDriver.ts b/apps/server/src/provider/Drivers/AntigravityDriver.ts
index f1f39e104b44c..e2a988355867b 100644
--- a/apps/server/src/provider/Drivers/AntigravityDriver.ts
+++ b/apps/server/src/provider/Drivers/AntigravityDriver.ts
@@ -46,8 +46,8 @@ import {
 import type * as AcpSessionRuntime from "@t3tools/provider-acp/server/AcpSessionRuntime";
 import type { ServerProviderDraft } from "@t3tools/provider-core/server/snapshotProbe";
 import {
-  removeAntigravityRuntimeTempDirs,
   removeAntigravitySessionFiles,
+  retireAntigravityRuntimeTempDirs,
 } from "../acp/AntigravitySessionFiles.ts";
 import * as IdAllocator from "@t3tools/provider-core/server/IdAllocator";
 import * as ProviderContinuationRequests from "@t3tools/provider-core/server/ProviderContinuationRequests";
@@ -150,9 +150,11 @@ export const AntigravityDriver: ProviderDriver<
       directories.runtimeTemp,
       path.join(profileDirectory, "antigravity-acp", "tmp"),
     ]) {
-      yield* removeAntigravityRuntimeTempDirs(directory).pipe(
+      const removeRetired = yield* retireAntigravityRuntimeTempDirs(directory).pipe(
         Effect.provideService(FileSystem.FileSystem, fileSystem),
+        Effect.provideService(Path.Path, path),
       );
+      yield* Effect.forkScoped(removeRetired);
     }
     const continuationIdentity = defaultProviderContinuationIdentity({
       driverKind: DRIVER,
diff --git a/apps/server/src/provider/acp/AntigravitySessionFiles.test.ts b/apps/server/src/provider/acp/AntigravitySessionFiles.test.ts
new file mode 100644
index 0000000000000..795e80b861e84
--- /dev/null
+++ b/apps/server/src/provider/acp/AntigravitySessionFiles.test.ts
@@ -0,0 +1,64 @@
+import * as NodeServices from "@effect/platform-node/NodeServices";
+import { expect, it } from "@effect/vitest";
+import * as Effect from "effect/Effect";
+import * as FileSystem from "effect/FileSystem";
+import * as Path from "effect/Path";
+import * as PlatformError from "effect/PlatformError";
+
+import { retireAntigravityRuntimeTempDirs } from "./AntigravitySessionFiles.ts";
+
+it.layer(NodeServices.layer)("retireAntigravityRuntimeTempDirs", (it) => {
+  it.effect("moves leftovers aside at once and deletes them, plus older retirees, later", () =>
+    Effect.gen(function* () {
+      const fs = yield* FileSystem.FileSystem;
+      const path = yield* Path.Path;
+      const parent = yield* fs.makeTempDirectoryScoped();
+      const runtimeTemp = path.join(parent, "abc123");
+      const orphan = path.join(runtimeTemp, "run-orphan", "_MEI123");
+      yield* fs.makeDirectory(orphan, { recursive: true });
+      yield* fs.writeFileString(path.join(orphan, "payload.bin"), "stale");
+      yield* fs.makeDirectory(path.join(parent, "abc123.old-unfinished", "runtime"), {
+        recursive: true,
+      });
+      yield* fs.makeDirectory(path.join(parent, "other-instance"));
+
+      const removeRetired = yield* retireAntigravityRuntimeTempDirs(runtimeTemp);
+      expect(yield* fs.exists(runtimeTemp)).toBe(false);
+      const retired = (yield* fs.readDirectory(parent)).filter((entry) =>
+        entry.startsWith("abc123.old-"),
+      );
+      expect(retired).toHaveLength(2);
+
+      yield* removeRetired;
+      expect((yield* fs.readDirectory(parent)).toSorted()).toEqual(["other-instance"]);
+    }).pipe(Effect.scoped),
+  );
+
+  it.effect(
+    "deletes leftovers inline when they cannot be moved aside, such as on a full disk",
+    () =>
+      Effect.gen(function* () {
+        const removed: Array<string> = [];
+        const fs = FileSystem.makeNoop({
+          exists: () => Effect.succeed(true),
+          makeTempDirectory: () =>
+            Effect.fail(
+              PlatformError.systemError({
+                _tag: "Unknown",
+                module: "FileSystem",
+                method: "makeTempDirectory",
+                description: "ENOSPC",
+              }),
+            ),
+          remove: (path) => Effect.sync(() => void removed.push(path)),
+          readDirectory: () => Effect.succeed([]),
+        });
+
+        const removeRetired = yield* retireAntigravityRuntimeTempDirs(
+          "/state/antigravity-tmp/abc123",
+        ).pipe(Effect.provideService(FileSystem.FileSystem, fs));
+        yield* removeRetired;
+        expect(removed).toEqual(["/state/antigravity-tmp/abc123"]);
+      }),
+  );
+});
diff --git a/apps/server/src/provider/acp/AntigravitySessionFiles.ts b/apps/server/src/provider/acp/AntigravitySessionFiles.ts
index 7a25c8323174d..819d79a05ed12 100644
--- a/apps/server/src/provider/acp/AntigravitySessionFiles.ts
+++ b/apps/server/src/provider/acp/AntigravitySessionFiles.ts
@@ -42,13 +42,35 @@ export const removeAntigravitySessionFiles = Effect.fn("removeAntigravitySession
   Effect.catch(() => Effect.logWarning("Could not remove temporary Antigravity session files.")),
 );
 
-/** Sweep only private runtimes before launch; Windows does not protect live extracted data files from deletion. */
-export const removeAntigravityRuntimeTempDirs = Effect.fn("removeAntigravityRuntimeTempDirs")(
+const warnRuntimeTempLeftovers = Effect.logWarning(
+  "Could not remove leftover Antigravity runtime temp files.",
+);
+
+/**
+ * Sweep only private runtimes before launch; Windows does not protect live extracted data files from deletion.
+ * Moves leftovers aside and returns their slow deletion (seconds on Windows) to run off the startup path.
+ */
+export const retireAntigravityRuntimeTempDirs = Effect.fn("retireAntigravityRuntimeTempDirs")(
   function* (tempDirectory: string) {
     const fs = yield* FileSystem.FileSystem;
-    yield* fs.remove(tempDirectory, { recursive: true, force: true });
+    const path = yield* Path.Path;
+    const parent = path.dirname(tempDirectory);
+    const prefix = `${path.basename(tempDirectory)}.old-`;
+    if (yield* fs.exists(tempDirectory)) {
+      yield* fs.makeTempDirectory({ directory: parent, prefix }).pipe(
+        Effect.flatMap((retired) => fs.rename(tempDirectory, path.join(retired, "runtime"))),
+        Effect.catch(() => fs.remove(tempDirectory, { recursive: true, force: true })),
+      );
+    }
+    const entries = yield* fs.readDirectory(parent).pipe(Effect.orElseSucceed(() => []));
+    return Effect.forEach(
+      entries.filter((entry) => entry.startsWith(prefix)),
+      (entry) =>
+        fs
+          .remove(path.join(parent, entry), { recursive: true, force: true })
+          .pipe(Effect.catch(() => warnRuntimeTempLeftovers)),
+      { discard: true },
+    );
   },
-  Effect.catch(() =>
-    Effect.logWarning("Could not remove leftover Antigravity runtime temp files."),
-  ),
+  Effect.catch(() => warnRuntimeTempLeftovers.pipe(Effect.as(Effect.void))),
 );