diff --git a/apps/mobile/src/lib/storage.test.ts b/apps/mobile/src/lib/storage.test.ts
index 83ff2db5748..b793f9f4586 100644
--- a/apps/mobile/src/lib/storage.test.ts
+++ b/apps/mobile/src/lib/storage.test.ts
@@ -1,10 +1,15 @@
-import { EnvironmentId } from "@t3tools/contracts";
-import { beforeEach, describe, expect, it, vi } from "vite-plus/test";
+import { assert } from "@effect/vitest";
+import * as Schema from "effect/Schema";
+import { EnvironmentId, type OrchestrationShellSnapshot } from "@t3tools/contracts";
+import { beforeEach, describe, it, vi } from "vite-plus/test";
 
 const mocks = vi.hoisted(() => {
   const values = new Map<string, string>();
+  const files = new Map<string, { text: string; deleted: boolean }>();
   return {
     clear: () => values.clear(),
+    clearFiles: () => files.clear(),
+    files,
     getItemAsync: vi.fn((key: string) => Promise.resolve(values.get(key) ?? null)),
     setItemAsync: vi.fn((key: string, value: string) => {
       values.set(key, value);
@@ -13,6 +18,57 @@ const mocks = vi.hoisted(() => {
   };
 });
 
+vi.mock("expo-file-system", () => ({
+  Directory: class {
+    readonly uri: string;
+
+    constructor(parent: string, name: string) {
+      this.uri = `${parent}/${name}`;
+    }
+
+    create(): void {
+      // Directory creation is idempotent for these storage tests.
+    }
+  },
+  File: class {
+    readonly uri: string;
+
+    constructor(directory: { readonly uri: string }, name: string) {
+      this.uri = `${directory.uri}/${name}`;
+    }
+
+    get exists(): boolean {
+      return mocks.files.has(this.uri) && mocks.files.get(this.uri)?.deleted === false;
+    }
+
+    create(): void {
+      mocks.files.set(this.uri, { text: "", deleted: false });
+    }
+
+    delete(): void {
+      const entry = mocks.files.get(this.uri);
+      if (entry) {
+        entry.deleted = true;
+      }
+    }
+
+    text(): string {
+      const entry = mocks.files.get(this.uri);
+      if (!entry || entry.deleted) {
+        throw new Error("missing file");
+      }
+      return entry.text;
+    }
+
+    write(text: string): void {
+      mocks.files.set(this.uri, { text, deleted: false });
+    }
+  },
+  Paths: {
+    document: "document",
+  },
+}));
+
 vi.mock("expo-secure-store", () => ({
   getItemAsync: mocks.getItemAsync,
   setItemAsync: mocks.setItemAsync,
@@ -30,9 +86,18 @@ vi.mock("./runtime", () => ({
   },
 }));
 
-import { loadSavedConnections, saveConnection } from "./storage";
+import {
+  loadCachedShellSnapshot,
+  loadSavedConnections,
+  saveCachedShellSnapshot,
+  saveConnection,
+  type CachedShellSnapshot,
+} from "./storage";
 import { toStableSavedRemoteConnection } from "./connection";
 
+const decodeUnknownJsonString = Schema.decodeUnknownSync(Schema.UnknownFromJsonString);
+const encodeUnknownJsonString = Schema.encodeUnknownSync(Schema.UnknownFromJsonString);
+
 const managedConnection = {
   environmentId: EnvironmentId.make("environment-1"),
   environmentLabel: "Desktop",
@@ -46,9 +111,30 @@ const managedConnection = {
   relayManaged: true,
 } as const;
 
+const cacheEnvironmentId = EnvironmentId.make("cache-environment-1");
+const otherCacheEnvironmentId = EnvironmentId.make("cache-environment-2");
+
+const cachedSnapshot: OrchestrationShellSnapshot = {
+  snapshotSequence: 1,
+  projects: [],
+  threads: [],
+  updatedAt: "2026-01-01T00:00:00.000Z",
+};
+
+const cacheFileUri = (environmentId: EnvironmentId) =>
+  `document/shell-snapshots/${encodeURIComponent(environmentId)}.json`;
+
+const writeCachedSnapshotFile = (environmentId: EnvironmentId, document: unknown) => {
+  mocks.files.set(cacheFileUri(environmentId), {
+    text: typeof document === "string" ? document : encodeUnknownJsonString(document),
+    deleted: false,
+  });
+};
+
 describe("mobile connection storage", () => {
   beforeEach(() => {
     mocks.clear();
+    mocks.clearFiles();
     vi.clearAllMocks();
   });
 
@@ -56,8 +142,8 @@ describe("mobile connection storage", () => {
     await saveConnection(managedConnection);
 
     const savedValue = mocks.setItemAsync.mock.calls[0]?.[1];
-    expect(savedValue).toBeDefined();
-    expect(JSON.parse(savedValue ?? "")).toEqual({
+    assert.notEqual(savedValue, undefined);
+    assert.deepStrictEqual(decodeUnknownJsonString(savedValue ?? ""), {
       connections: [toStableSavedRemoteConnection(managedConnection)],
     });
   });
@@ -65,8 +151,46 @@ describe("mobile connection storage", () => {
   it("loads relay-managed connection metadata without a cached access token", async () => {
     await saveConnection(managedConnection);
 
-    await expect(loadSavedConnections()).resolves.toEqual([
+    assert.deepStrictEqual(await loadSavedConnections(), [
       toStableSavedRemoteConnection(managedConnection),
     ]);
   });
+
+  it("loads cached shell snapshots through the schema JSON codec", async () => {
+    await saveCachedShellSnapshot(cacheEnvironmentId, cachedSnapshot);
+
+    const loaded = await loadCachedShellSnapshot(cacheEnvironmentId);
+
+    assert.deepStrictEqual(loaded?.snapshot, cachedSnapshot);
+    assert.equal(loaded?.environmentId, cacheEnvironmentId);
+  });
+
+  it("ignores malformed cached shell snapshot JSON", async () => {
+    writeCachedSnapshotFile(cacheEnvironmentId, "{");
+
+    assert.equal(await loadCachedShellSnapshot(cacheEnvironmentId), null);
+  });
+
+  it("ignores cached shell snapshots with an unsupported schema version", async () => {
+    writeCachedSnapshotFile(cacheEnvironmentId, {
+      schemaVersion: 2,
+      environmentId: cacheEnvironmentId,
+      snapshotReceivedAt: "2026-01-01T00:00:00.000Z",
+      snapshot: cachedSnapshot,
+    });
+
+    assert.equal(await loadCachedShellSnapshot(cacheEnvironmentId), null);
+  });
+
+  it("ignores cached shell snapshots written for a different environment", async () => {
+    const document: CachedShellSnapshot = {
+      schemaVersion: 1,
+      environmentId: otherCacheEnvironmentId,
+      snapshotReceivedAt: "2026-01-01T00:00:00.000Z",
+      snapshot: cachedSnapshot,
+    };
+    writeCachedSnapshotFile(cacheEnvironmentId, document);
+
+    assert.equal(await loadCachedShellSnapshot(cacheEnvironmentId), null);
+  });
 });
diff --git a/apps/mobile/src/lib/storage.ts b/apps/mobile/src/lib/storage.ts
index 2f9e4962c1a..a97c49158f6 100644
--- a/apps/mobile/src/lib/storage.ts
+++ b/apps/mobile/src/lib/storage.ts
@@ -35,7 +35,9 @@ const CachedShellSnapshotSchema = Schema.Struct({
   snapshotReceivedAt: Schema.String,
   snapshot: OrchestrationShellSnapshot,
 });
-const decodeCachedShellSnapshot = Schema.decodeUnknownOption(CachedShellSnapshotSchema);
+const CachedShellSnapshotJson = Schema.fromJsonString(CachedShellSnapshotSchema);
+const decodeCachedShellSnapshotJson = Schema.decodeUnknownOption(CachedShellSnapshotJson);
+const encodeCachedShellSnapshotJson = Schema.encodeOption(CachedShellSnapshotJson);
 
 async function readStorageItem(key: string): Promise<string | null> {
   return await SecureStore.getItemAsync(key);
@@ -80,8 +82,7 @@ export async function loadCachedShellSnapshot(
       return null;
     }
 
-    const parsed = JSON.parse(await file.text()) as unknown;
-    const decoded = decodeCachedShellSnapshot(parsed);
+    const decoded = decodeCachedShellSnapshotJson(await file.text());
     if (Option.isNone(decoded) || decoded.value.environmentId !== environmentId) {
       return null;
     }
@@ -106,11 +107,15 @@ export async function saveCachedShellSnapshot(
       snapshotReceivedAt: new Date().toISOString(),
       snapshot,
     };
+    const encoded = encodeCachedShellSnapshotJson(document);
+    if (Option.isNone(encoded)) {
+      return;
+    }
 
     if (!file.exists) {
       file.create({ intermediates: true, overwrite: true });
     }
-    file.write(JSON.stringify(document));
+    file.write(encoded.value);
   } catch {
     // Cache persistence is best-effort and should never block live data.
   }
diff --git a/packages/shared/src/DrainableWorker.test.ts b/packages/shared/src/DrainableWorker.test.ts
index 8e4c654e2e4..b88eaca8eb7 100644
--- a/packages/shared/src/DrainableWorker.test.ts
+++ b/packages/shared/src/DrainableWorker.test.ts
@@ -1,5 +1,4 @@
-import { it } from "@effect/vitest";
-import { describe, expect } from "vite-plus/test";
+import { assert, describe, it } from "@effect/vitest";
 import * as Deferred from "effect/Deferred";
 import * as Effect from "effect/Effect";
 
@@ -45,12 +44,12 @@ describe("makeDrainableWorker", () => {
         yield* Deferred.succeed(releaseFirst, undefined);
         yield* Deferred.await(secondStarted);
 
-        expect(yield* Deferred.isDone(drained)).toBe(false);
+        assert.equal(yield* Deferred.isDone(drained), false);
 
         yield* Deferred.succeed(releaseSecond, undefined);
         yield* Deferred.await(drained);
 
-        expect(processed).toEqual(["first", "second"]);
+        assert.deepStrictEqual(processed, ["first", "second"]);
       }),
     ),
   );
diff --git a/packages/shared/src/KeyedCoalescingWorker.test.ts b/packages/shared/src/KeyedCoalescingWorker.test.ts
index 8bfc1a340a6..0354fb30095 100644
--- a/packages/shared/src/KeyedCoalescingWorker.test.ts
+++ b/packages/shared/src/KeyedCoalescingWorker.test.ts
@@ -1,5 +1,4 @@
-import { it } from "@effect/vitest";
-import { describe, expect } from "vite-plus/test";
+import { assert, describe, it } from "@effect/vitest";
 import * as Deferred from "effect/Deferred";
 import * as Effect from "effect/Effect";
 
@@ -47,12 +46,12 @@ describe("makeKeyedCoalescingWorker", () => {
         yield* Deferred.succeed(releaseFirst, undefined);
         yield* Deferred.await(secondStarted);
 
-        expect(yield* Deferred.isDone(drained)).toBe(false);
+        assert.equal(yield* Deferred.isDone(drained), false);
 
         yield* Deferred.succeed(releaseSecond, undefined);
         yield* Deferred.await(drained);
 
-        expect(processed).toEqual(["terminal-1:first", "terminal-1:second"]);
+        assert.deepStrictEqual(processed, ["terminal-1:first", "terminal-1:second"]);
       }),
     ),
   );
@@ -90,7 +89,7 @@ describe("makeKeyedCoalescingWorker", () => {
         yield* Deferred.await(secondProcessed);
         yield* worker.drainKey("terminal-1");
 
-        expect(processed).toEqual(["terminal-1:first", "terminal-1:second"]);
+        assert.deepStrictEqual(processed, ["terminal-1:first", "terminal-1:second"]);
       }),
     ),
   );