From e7a4aa1377c650defd4a7d6bc2736b84f2a3b075 Mon Sep 17 00:00:00 2001
From: Jinwoo-H <jinwoo0825@gmail.com>
Date: Mon, 7 Sep 2026 14:36:06 -0400
Subject: [PATCH] fix(mobile): accept only a full digest shape as an
 already-digested tab id

---
 mobile/src/cache/session-tab-strip-cache.test.ts | 13 +++++++++++++
 mobile/src/cache/session-tab-strip-cache.ts      |  4 +++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/mobile/src/cache/session-tab-strip-cache.test.ts b/mobile/src/cache/session-tab-strip-cache.test.ts
index ea167f4b666..d7815a912c0 100644
--- a/mobile/src/cache/session-tab-strip-cache.test.ts
+++ b/mobile/src/cache/session-tab-strip-cache.test.ts
@@ -221,6 +221,19 @@ describe('session tab strip cache', () => {
     expect(loaded?.activeTabId).toBe(digested)
   })
 
+  it('digests a wire id that merely starts with the digest prefix', async () => {
+    const key = getSessionTabStripCacheKey('host-1', 'wt-1')
+    const id = 'cached:/Users/someone/private-file.md'
+    saveCachedSessionTabStrip(key, {
+      tabs: [{ id, type: 'file', title: 'x', agentId: null }],
+      activeTabId: id
+    })
+    await vi.advanceTimersByTimeAsync(300)
+
+    expectDigestedIds(readCachedSessionTabStrip(key)?.tabs.map((tab) => tab.id) ?? [], 1)
+    expect(String(asyncStorage.setItem.mock.calls.at(-1)?.[1])).not.toContain('private-file')
+  })
+
   it('keeps only a known agent id, since the hook-reported one is free text', async () => {
     const key = getSessionTabStripCacheKey('host-1', 'wt-1')
     saveCachedSessionTabStrip(key, {
diff --git a/mobile/src/cache/session-tab-strip-cache.ts b/mobile/src/cache/session-tab-strip-cache.ts
index 7ff6d2d6c0b..6ceccabe80b 100644
--- a/mobile/src/cache/session-tab-strip-cache.ts
+++ b/mobile/src/cache/session-tab-strip-cache.ts
@@ -27,6 +27,8 @@ const WRITE_DEBOUNCE_MS = 250
 // the stored blob stays small.
 const WORKSPACE_DIGEST_LENGTH = 32
 const TAB_DIGEST_PREFIX = 'cached:'
+// The whole shape, not the prefix: a wire id that merely starts with the prefix is still wire text.
+const DIGESTED_TAB_ID = /^cached:[0-9a-f]{32}$/
 
 type StoredWorkspace = { key: string; preview: MobileSessionTabStripPreview }
 type StoredFile = { workspaces: StoredWorkspace[] }
@@ -150,7 +152,7 @@ function digestWorkspaceId(worktreeId: string): string {
 // Prefixed so a raw id can never be mistaken for one already digested, and so a live tab's
 // id can never collide with a stored row's by construction.
 function digestTabId(tabId: string): string {
-  return tabId.startsWith(TAB_DIGEST_PREFIX) ? tabId : `${TAB_DIGEST_PREFIX}${digestHex(tabId)}`
+  return DIGESTED_TAB_ID.test(tabId) ? tabId : `${TAB_DIGEST_PREFIX}${digestHex(tabId)}`
 }
 
 function digestHex(value: string): string {