diff --git a/src/state/session/__tests__/mock-fetch.ts b/src/state/session/__tests__/mock-fetch.ts
new file mode 100644
index 0000000000..a107d8dc3c
--- /dev/null
+++ b/src/state/session/__tests__/mock-fetch.ts
@@ -0,0 +1,126 @@
+import {jest} from '@jest/globals'
+
+import {type SessionAccount} from '../types'
+
+/*
+ * Shared fixtures for the suites that drive a real `PasswordSession` over a
+ * stubbed network. Not a suite itself - the filename deliberately avoids the
+ * `-test` suffix so jest does not collect it.
+ */
+
+export const DID = 'did:plc:example123'
+export const HANDLE = 'alice.test'
+export const SERVICE = 'https://bsky.social'
+/** A PDS host an account may be pinned to by its stored `pdsUrl`. */
+export const PDS_HOST = 'https://shimeji.us-east.host.bsky.network'
+/** A different PDS host, delivered by the didDoc a refresh returns. */
+export const DIDDOC_PDS_HOST = 'https://morel.us-west.host.bsky.network'
+
+export function json(body: unknown, status = 200) {
+  return new Response(JSON.stringify(body), {
+    status,
+    headers: {'content-type': 'application/json'},
+  })
+}
+
+/** A minimal valid DID document whose only service entry is a PDS. */
+export function makeDidDoc(pdsUrl: string, did: string = DID) {
+  return {
+    id: did,
+    service: [
+      {
+        id: '#atproto_pds',
+        type: 'AtprotoPersonalDataServer',
+        serviceEndpoint: pdsUrl,
+      },
+    ],
+  }
+}
+
+export function makeAccount(
+  overrides: Partial<SessionAccount> = {},
+): SessionAccount {
+  return {
+    service: SERVICE,
+    did: DID,
+    handle: HANDLE,
+    email: 'alice@example.com',
+    emailConfirmed: true,
+    emailAuthFactor: false,
+    refreshJwt: 'refresh-jwt',
+    accessJwt: 'access-jwt',
+    signupQueued: false,
+    active: true,
+    status: undefined,
+    pdsUrl: undefined,
+    isSelfHosted: false,
+    ...overrides,
+  }
+}
+
+/**
+ * Build a mock `fetch` that returns canned XRPC responses keyed by the last
+ * path segment (nsid). `refreshSession` returns fresh tokens; `getSession`
+ * echoes the account; anything else returns an empty 200.
+ *
+ * The refresh response carries both `emailConfirmed` and a `didDoc` so the
+ * library has no reason to make a `getSession` follow-up call, which keeps the
+ * recorded request list assertable. Its didDoc points at
+ * {@link DIDDOC_PDS_HOST}, a different host from {@link PDS_HOST}, so PDS
+ * re-routing after a refresh is observable.
+ */
+export function makeMockFetch(
+  overrides: Record<
+    string,
+    (url: string, init: RequestInit) => Response | Promise<Response>
+  > = {},
+) {
+  return jest.fn(
+    /*
+     * PasswordSession calls fetch with a URL object (new URL(path, service));
+     * asFetch() below widens the mock to the full fetch signature it expects.
+     */
+    async (input: URL | string, init: RequestInit = {}): Promise<Response> => {
+      const url = input instanceof URL ? input.href : input
+      const nsid = url.split('/xrpc/')[1]?.split('?')[0]
+      const handler = nsid ? overrides[nsid] : undefined
+      if (handler) {
+        return handler(url, init)
+      }
+      if (nsid === 'com.atproto.server.refreshSession') {
+        return json({
+          accessJwt: 'access-jwt-2',
+          refreshJwt: 'refresh-jwt-2',
+          handle: HANDLE,
+          did: DID,
+          email: 'alice@example.com',
+          emailConfirmed: true,
+          didDoc: makeDidDoc(DIDDOC_PDS_HOST),
+          active: true,
+        })
+      }
+      if (nsid === 'com.atproto.server.getSession') {
+        return json({
+          did: DID,
+          handle: HANDLE,
+          email: 'alice@example.com',
+          emailConfirmed: true,
+          active: true,
+        })
+      }
+      return json({})
+    },
+  )
+}
+
+export type MockFetch = ReturnType<typeof makeMockFetch>
+
+/** Cast a jest fetch mock to the `fetch` type PasswordSession options expect. */
+export function asFetch(mock: MockFetch): typeof fetch {
+  return mock as unknown as typeof fetch
+}
+
+/** The URLs a mock fetch was called with, in order. */
+export function urlsOf(mock: MockFetch): string[] {
+  return mock.mock.calls.map(c => (c[0] instanceof URL ? c[0].href : c[0]))
+}
diff --git a/src/state/session/__tests__/provider-abort-test.tsx b/src/state/session/__tests__/provider-abort-test.tsx
index 0bf5c08f21..fdc1585981 100644
--- a/src/state/session/__tests__/provider-abort-test.tsx
+++ b/src/state/session/__tests__/provider-abort-test.tsx
@@ -1,4 +1,4 @@
-import {describe, expect, it, jest} from '@jest/globals'
+import {beforeEach, describe, expect, it, jest} from '@jest/globals'
 import {act, render} from '@testing-library/react-native'
 
 /*
@@ -86,8 +86,20 @@ function renderProvider(): SessionApiContext {
  * for an account the app is no longer tracking.
  */
 describe('superseded session tasks dispose their bundle', () => {
+  /*
+   * Without this, a recorded call from an earlier test satisfies a later
+   * assertion. The tagged bundles below are the other half of that guard: two
+   * `{}` literals are structurally equal, so `toHaveBeenCalledWith` could not
+   * tell one test's bundle from the other's even within a cleared mock.
+   */
+  beforeEach(() => {
+    mockLogin.mockReset()
+    mockCreateAccount.mockReset()
+    mockDisposeBundle.mockReset()
+  })
+
   it('disposes the bundle of an aborted login', async () => {
-    const bundle = {} as never
+    const bundle = {tag: 'login-bundle'} as never
     let resolveLogin!: (value: unknown) => void
     mockLogin.mockReturnValueOnce(
       new Promise(resolve => {
@@ -110,7 +122,7 @@ describe('superseded session tasks dispose their bundle', () => {
   })
 
   it('disposes the bundle of an aborted createAccount', async () => {
-    const bundle = {} as never
+    const bundle = {tag: 'create-account-bundle'} as never
     let resolveCreate!: (value: unknown) => void
     mockCreateAccount.mockReturnValueOnce(
       new Promise(resolve => {
diff --git a/src/state/session/__tests__/provider-session-events-test.tsx b/src/state/session/__tests__/provider-session-events-test.tsx
new file mode 100644
index 0000000000..778f83d508
--- /dev/null
+++ b/src/state/session/__tests__/provider-session-events-test.tsx
@@ -0,0 +1,476 @@
+import {type SessionData} from '@atproto/lex-password-session'
+import {beforeEach, describe, expect, it, jest} from '@jest/globals'
+import {act, render} from '@testing-library/react-native'
+
+import {type Schema} from '#/state/persisted/schema'
+import {type SessionAccount} from '../types'
+
+/*
+ * The provider pulls the whole app shell in through `#/state/util` and the
+ * account factories. These mocks cut the tree back to the session lifecycle
+ * itself, which is all these tests drive. They mirror provider-abort-test.tsx,
+ * plus a stateful `#/state/persisted` (this suite drives cross-tab updates and
+ * the expiry rescue's fresh persisted read) and an observable
+ * `emitSessionDropped`.
+ */
+const mockPersisted: {session: Schema['session']; latest: Schema['session']} = {
+  session: {accounts: [], currentAccount: undefined},
+  latest: {accounts: [], currentAccount: undefined},
+}
+/*
+ * Every registered listener is kept, not just the newest. The provider's
+ * subscription effect re-runs on every state change, so a callback captured
+ * before a dispatch is exactly the stale-closure case the shouldActivate guard
+ * exists to catch.
+ */
+const mockPersistedListeners: ((value: Schema['session']) => void)[] = []
+jest.mock('#/state/persisted', () => {
+  const {
+    defaults,
+  }: typeof import('#/state/persisted/schema') = require('#/state/persisted/schema')
+  return {
+    defaults,
+    get: (key: string) =>
+      key === 'session'
+        ? mockPersisted.session
+        : defaults[key as keyof typeof defaults],
+    readLatest: (key: string) =>
+      key === 'session'
+        ? mockPersisted.latest
+        : defaults[key as keyof typeof defaults],
+    write: () => Promise.resolve(),
+    onUpdate: (_key: string, cb: (value: Schema['session']) => void) => {
+      mockPersistedListeners.push(cb)
+      return () => {}
+    },
+  }
+})
+jest.mock('#/state/util', () => ({useCloseAllActiveElements: () => () => {}}))
+jest.mock('#/components/dialogs/Context', () => ({
+  useGlobalDialogsControlContext: () => ({signinDialogControl: {open() {}}}),
+}))
+jest.mock('#/analytics', () => ({
+  AnalyticsContext: ({children}: {children: React.ReactNode}) => children,
+  useAnalyticsBase: () => ({metric() {}, logger: {debug() {}, error() {}}}),
+  utils: {accountToSessionMetadata: () => ({}), useMeta: () => undefined},
+}))
+jest.mock('#/state/shell/onboarding', () => ({
+  useOnboardingDispatch: () => () => {},
+}))
+jest.mock('#/ageAssurance/data', () => ({
+  clearAgeAssuranceServerDataForAll: () => {},
+  clearAgeAssuranceServerDataForDid: () => {},
+}))
+jest.mock('#/lib/persisted-query-storage', () => ({
+  clearPersistedQueryStorage: () => Promise.resolve(),
+}))
+jest.mock('#/lib/notifications/notifications', () => ({
+  unregisterPushToken: () => Promise.resolve(),
+}))
+jest.mock('jwt-decode', () => ({jwtDecode: () => ({})}))
+
+const mockEmitSessionDropped = jest.fn()
+jest.mock('#/state/events', () => ({
+  emitSessionDropped: () => mockEmitSessionDropped(),
+  emitNetworkConfirmed: () => {},
+  emitNetworkLost: () => {},
+}))
+
+/*
+ * The factories are stubbed so a test controls exactly what each one returns
+ * and when. `createSessionBundleFromStoredAccount` is stubbed faithfully rather
+ * than replaced by a constant: it must still consult `shouldActivate` and
+ * decline to hand back a bundle when the guard rejects, because that decision
+ * is what these tests observe. Its disposal of a rejected bundle is pinned by
+ * session-core-test; here we only assert what the provider does with the
+ * result.
+ */
+const mockLogin = jest.fn<(...args: unknown[]) => Promise<unknown>>()
+const mockResume = jest.fn<(...args: unknown[]) => Promise<unknown>>()
+const mockDisposeBundle = jest.fn()
+type Rebuild = {
+  account: SessionAccount
+  shouldActivate: boolean
+  bundle: FakeBundle
+}
+const mockRebuilds: Rebuild[] = []
+const mockRebuild = jest.fn(
+  (
+    account: SessionAccount,
+    _onSessionChange: unknown,
+    shouldActivate: (
+      bundle: unknown,
+      account: SessionAccount,
+    ) => boolean = () => true,
+  ) => {
+    const bundle = makeBundle(account)
+    const activated = shouldActivate(bundle, account)
+    mockRebuilds.push({account, shouldActivate: activated, bundle})
+    return activated ? {bundle, account} : undefined
+  },
+)
+jest.mock('../session-core', () => ({
+  ...jest.requireActual<object>('../session-core'),
+  createSessionBundleAndLogin: (...args: unknown[]) => mockLogin(...args),
+  createSessionBundleAndResume: (...args: unknown[]) => mockResume(...args),
+  createSessionBundleFromStoredAccount: (...args: unknown[]) =>
+    // @ts-expect-error the stub's arity is checked by its own signature
+    mockRebuild(...args),
+  disposeBundle: (bundle: unknown) => mockDisposeBundle(bundle),
+}))
+jest.mock('../create-account', () => ({
+  createSessionBundleAndCreateAccount: () => new Promise(() => {}),
+}))
+
+import {Provider, useSession, useSessionApi} from '#/state/session'
+import {
+  type OnSessionChange,
+  type SessionBundle,
+} from '#/state/session/session-core'
+import {type SessionApiContext} from '#/state/session/types'
+
+const DID = 'did:plc:example123'
+const SERVICE = 'https://bsky.social/'
+
+function makeAccount(overrides: Partial<SessionAccount> = {}): SessionAccount {
+  return {
+    service: SERVICE,
+    did: DID,
+    handle: 'alice.test',
+    email: 'alice@example.com',
+    emailConfirmed: true,
+    emailAuthFactor: false,
+    refreshJwt: 'refresh-jwt-1',
+    accessJwt: 'access-jwt-1',
+    signupQueued: false,
+    active: true,
+    status: undefined,
+    pdsUrl: undefined,
+    isSelfHosted: false,
+    ...overrides,
+  }
+}
+
+/*
+ * The provider only ever reads `bundle.agent` (for context) and
+ * `bundle.session.destroyed` / `bundle.session.session` (for the cross-tab
+ * token comparison), and otherwise treats a bundle as an opaque identity. A
+ * literal with those fields is enough, and keeps a real PasswordSession - with
+ * its network and refresh machinery - out of a suite about provider dispatch.
+ */
+type FakeBundle = {
+  session: {destroyed: boolean; session: SessionData}
+  agent: object
+  service: URL
+}
+
+function makeBundle(account: SessionAccount): FakeBundle {
+  return {
+    session: {
+      destroyed: false,
+      session: {
+        accessJwt: account.accessJwt ?? '',
+        refreshJwt: account.refreshJwt ?? '',
+        /* SessionData types these as branded strings; the values are fixtures */
+        handle: account.handle as `${string}.${string}`,
+        did: account.did as `did:${string}:${string}`,
+        active: true,
+        service: account.service,
+      },
+    },
+    agent: {},
+    service: new URL(account.service),
+  }
+}
+
+type Harness = {
+  api: SessionApiContext
+  /** The provider's own onSessionChange, as handed to a session factory. */
+  onSessionChange: OnSessionChange
+  currentAccount: () => SessionAccount | undefined
+  hasSession: () => boolean
+}
+
+/**
+ * Render the provider, log an account in through the stubbed login factory, and
+ * hand back the api plus the `onSessionChange` the factory received. Firing
+ * that callback is how a test synthesizes a session event from a live bundle.
+ */
+async function renderLoggedIn(
+  account: SessionAccount,
+  bundle: FakeBundle,
+): Promise<Harness> {
+  let api!: SessionApiContext
+  let session!: ReturnType<typeof useSession>
+  function Probe() {
+    api = useSessionApi()
+    session = useSession()
+    return null
+  }
+  render(
+    <Provider>
+      <Probe />
+    </Provider>,
+  )
+
+  let captured!: OnSessionChange
+  mockLogin.mockImplementationOnce((...args: unknown[]) => {
+    captured = args[1] as OnSessionChange
+    return Promise.resolve({bundle, account})
+  })
+  await act(async () => {
+    await api.login({} as never, 'LoginForm')
+  })
+
+  return {
+    api,
+    onSessionChange: captured,
+    currentAccount: () => session.currentAccount,
+    hasSession: () => session.hasSession,
+  }
+}
+
+/** The dying payload PasswordSession threads through its `onDeleted` hook. */
+function dyingData(refreshJwt: string): SessionData {
+  return {
+    accessJwt: 'dead-access-jwt',
+    refreshJwt,
+    handle: 'alice.test',
+    did: DID,
+    active: true,
+    service: SERVICE,
+  }
+}
+
+beforeEach(() => {
+  mockPersisted.session = {accounts: [], currentAccount: undefined}
+  mockPersisted.latest = {accounts: [], currentAccount: undefined}
+  mockPersistedListeners.length = 0
+  mockRebuilds.length = 0
+  mockLogin.mockReset()
+  mockResume.mockReset()
+  mockRebuild.mockClear()
+  mockDisposeBundle.mockReset()
+  mockEmitSessionDropped.mockReset()
+})
+
+/*
+ * A stale tab can expire a refresh token that another tab has already rotated
+ * past. Logging every tab out on that event is the known-worst failure in this
+ * subsystem, so the provider first looks for a newer token generation and
+ * rebuilds onto it, only falling through to logout when there is nothing left
+ * to try.
+ */
+describe('expiry rescue', () => {
+  it('rebuilds onto a fresher persisted generation instead of logging out', async () => {
+    const account = makeAccount()
+    const bundle = makeBundle(account)
+    const {onSessionChange, hasSession, currentAccount} = await renderLoggedIn(
+      account,
+      bundle,
+    )
+
+    /* another tab already rotated to generation 2 and wrote it to storage */
+    const fresher = makeAccount({
+      accessJwt: 'access-jwt-2',
+      refreshJwt: 'refresh-jwt-2',
+    })
+    mockPersisted.latest = {accounts: [fresher], currentAccount: fresher}
+
+    act(() => {
+      onSessionChange(
+        bundle as unknown as SessionBundle,
+        DID,
+        'expired',
+        dyingData('refresh-jwt-1'),
+      )
+    })
+
+    /* the rescue rebuilt onto the fresher generation ... */
+    expect(mockRebuilds.length).toBe(1)
+    expect(mockRebuilds[0].account.refreshJwt).toBe('refresh-jwt-2')
+    /* ... and adopted it, without ever reporting the session as dropped */
+    expect(hasSession()).toBe(true)
+    expect(currentAccount()?.refreshJwt).toBe('refresh-jwt-2')
+    expect(mockEmitSessionDropped).not.toHaveBeenCalled()
+  })
+
+  it('drops the session and logs out when there is no fresher generation', async () => {
+    const account = makeAccount()
+    const bundle = makeBundle(account)
+    const {onSessionChange, hasSession, currentAccount} = await renderLoggedIn(
+      account,
+      bundle,
+    )
+
+    /* storage agrees the dying token is the newest one anybody has */
+    mockPersisted.latest = {accounts: [account], currentAccount: account}
+
+    act(() => {
+      onSessionChange(
+        bundle as unknown as SessionBundle,
+        DID,
+        'expired',
+        dyingData('refresh-jwt-1'),
+      )
+    })
+
+    expect(mockRebuilds.length).toBe(0)
+    expect(mockEmitSessionDropped).toHaveBeenCalledTimes(1)
+    expect(hasSession()).toBe(false)
+    /* the reducer cleared the dead credentials rather than keeping them */
+    expect(currentAccount()).toBe(undefined)
+  })
+
+  it('does not retry a generation that already failed', async () => {
+    const account = makeAccount()
+    const bundle = makeBundle(account)
+    const {onSessionChange, hasSession} = await renderLoggedIn(account, bundle)
+
+    const gen2 = makeAccount({
+      accessJwt: 'access-jwt-2',
+      refreshJwt: 'refresh-jwt-2',
+    })
+    mockPersisted.latest = {accounts: [gen2], currentAccount: gen2}
+
+    /* generation 1 dies and is rescued onto generation 2 */
+    act(() => {
+      onSessionChange(
+        bundle as unknown as SessionBundle,
+        DID,
+        'expired',
+        dyingData('refresh-jwt-1'),
+      )
+    })
+    expect(mockRebuilds.length).toBe(1)
+    const rescued = mockRebuilds[0].bundle
+
+    /*
+     * Generation 2 dies too, and a stale tab has meanwhile written generation 1
+     * back to storage. It differs from the dying token, so only the record of
+     * its earlier failure can reject it.
+     */
+    mockPersisted.latest = {accounts: [account], currentAccount: account}
+    act(() => {
+      onSessionChange(
+        rescued as unknown as SessionBundle,
+        DID,
+        'expired',
+        dyingData('refresh-jwt-2'),
+      )
+    })
+
+    expect(mockRebuilds.length).toBe(1)
+    expect(mockEmitSessionDropped).toHaveBeenCalledTimes(1)
+    expect(hasSession()).toBe(false)
+  })
+})
+
+/** Deliver a cross-tab `persisted` update to the provider's newest listener. */
+function emitSynced(session: Schema['session']) {
+  mockPersistedListeners[mockPersistedListeners.length - 1](session)
+}
+
+/*
+ * A `PasswordSession` cannot be patched in place, so adopting tokens another
+ * tab refreshed means rebuilding the bundle. Doing that for every broadcast
+ * would churn the agent (and the React tree under it) constantly, so the
+ * provider rebuilds only when the tokens actually moved, and guards the swap
+ * against the store having advanced underneath it.
+ */
+describe('cross-tab sync', () => {
+  it('short-circuits an update carrying the tokens the live session already has', async () => {
+    const account = makeAccount()
+    const bundle = makeBundle(account)
+    const {hasSession} = await renderLoggedIn(account, bundle)
+
+    act(() => {
+      emitSynced({accounts: [account], currentAccount: account})
+    })
+
+    /* identical tokens: nothing to adopt, so no rebuild */
+    expect(mockRebuilds.length).toBe(0)
+    expect(hasSession()).toBe(true)
+  })
+
+  it('rebuilds onto tokens another tab rotated', async () => {
+    const account = makeAccount()
+    const bundle = makeBundle(account)
+    const {currentAccount} = await renderLoggedIn(account, bundle)
+
+    const rotated = makeAccount({
+      accessJwt: 'access-jwt-2',
+      refreshJwt: 'refresh-jwt-2',
+    })
+    act(() => {
+      emitSynced({accounts: [rotated], currentAccount: rotated})
+    })
+
+    expect(mockRebuilds.length).toBe(1)
+    expect(mockRebuilds[0].account.refreshJwt).toBe('refresh-jwt-2')
+    expect(currentAccount()?.refreshJwt).toBe('refresh-jwt-2')
+  })
+
+  it('declines to activate a rebuild once the store has moved past the bundle it was built for', async () => {
+    const account = makeAccount()
+    const bundle = makeBundle(account)
+    await renderLoggedIn(account, bundle)
+
+    const gen2 = makeAccount({
+      accessJwt: 'access-jwt-2',
+      refreshJwt: 'refresh-jwt-2',
+    })
+    const gen3 = makeAccount({
+      accessJwt: 'access-jwt-3',
+      refreshJwt: 'refresh-jwt-3',
+    })
+
+    /*
+     * Two broadcasts land back to back inside one act(), so React does not
+     * commit (and the effect does not re-subscribe) between them: the second
+     * runs the listener registered while the ORIGINAL bundle was current, even
+     * though the store has since advanced to the generation-2 rebuild.
+     */
+    const listener = mockPersistedListeners[mockPersistedListeners.length - 1]
+    act(() => {
+      listener({accounts: [gen2], currentAccount: gen2})
+      listener({accounts: [gen3], currentAccount: gen3})
+    })
+
+    expect(mockRebuilds.length).toBe(2)
+    expect(mockRebuilds[0].shouldActivate).toBe(true)
+    /* the stale closure's bundle is no longer current, so the swap is refused */
+    expect(mockRebuilds[1].account.refreshJwt).toBe('refresh-jwt-3')
+    expect(mockRebuilds[1].shouldActivate).toBe(false)
+  })
+
+  it('cancels pending work when another tab logs the account out', async () => {
+    const account = makeAccount()
+    const bundle = makeBundle(account)
+    const {api} = await renderLoggedIn(account, bundle)
+
+    /* a resume is in flight and will resolve only after the cross-tab logout */
+    const resumedBundle = makeBundle(account)
+    let finishResume!: (value: unknown) => void
+    mockResume.mockReturnValueOnce(
+      new Promise(resolve => {
+        finishResume = resolve
+      }),
+    )
+    const pending = api.resumeSession(account)
+
+    const loggedOut = makeAccount({accessJwt: undefined, refreshJwt: undefined})
+    act(() => {
+      emitSynced({accounts: [loggedOut], currentAccount: loggedOut})
+    })
+
+    await act(async () => {
+      finishResume({bundle: resumedBundle, account})
+      await pending
+    })
+
+    /* the superseded resume disposed its bundle rather than signing back in */
+    expect(mockDisposeBundle).toHaveBeenCalledWith(resumedBundle)
+    expect(mockRebuilds.length).toBe(0)
+  })
+})
diff --git a/src/state/session/__tests__/session-core-test.ts b/src/state/session/__tests__/session-core-test.ts
index 7551f95d2a..bb1896d389 100644
--- a/src/state/session/__tests__/session-core-test.ts
+++ b/src/state/session/__tests__/session-core-test.ts
@@ -12,6 +12,31 @@ jest.mock('#/state/events', () => ({
   emitNetworkLost: jest.fn(),
 }))
 
+/*
+ * `makeSessionHooks` reports a throwing `onSessionChange` through the logger
+ * rather than letting it escape into PasswordSession's session promise. Stub
+ * the module so that report is assertable (and so nothing reaches the real
+ * transports).
+ */
+const mockLoggerError = jest.fn()
+jest.mock('#/logger', () => {
+  const noopLogger = {
+    error: (...args: unknown[]) => mockLoggerError(...args),
+    warn: () => {},
+    info: () => {},
+    log: () => {},
+    debug: () => {},
+  }
+  return {
+    logger: noopLogger,
+    Logger: {
+      create: () => noopLogger,
+      Context: new Proxy({}, {get: (_t, key) => String(key)}),
+      Level: {},
+    },
+  }
+})
+
 /*
  * `prefetchAgeAssuranceServerData` is a genuine prep await in each factory
  * (moderation config is synchronous, so the AA prefetch is where the factory
@@ -71,32 +96,29 @@ import {
   buildBundle,
   createSessionBundleFromStoredAccount,
   disposeBundle,
+  finishPreparation,
   makeSessionHooks,
   registerBundleKillSwitch,
   sessionAccountToSessionData,
   type SessionBundle,
   sessionDataToSessionAccount,
 } from '../session-core'
-
-const DID = 'did:plc:example123'
-const HANDLE = 'alice.test'
-const SERVICE = 'https://bsky.social'
-const PDS_URL = 'https://shimeji.us-east.host.bsky.network'
+import {
+  asFetch,
+  DID,
+  HANDLE,
+  makeAccount,
+  makeDidDoc,
+  makeMockFetch,
+  PDS_HOST as PDS_URL,
+  SERVICE,
+} from './mock-fetch'
 
 function synthDidDoc(
   did: string,
   pdsUrl: string,
 ): NonNullable<SessionData['didDoc']> {
-  return {
-    id: did,
-    service: [
-      {
-        id: '#atproto_pds',
-        type: 'AtprotoPersonalDataServer',
-        serviceEndpoint: pdsUrl,
-      },
-    ],
-  }
+  return makeDidDoc(pdsUrl, did)
 }
 
 function makeSessionData(overrides: Partial<SessionData> = {}): SessionData {
@@ -342,25 +364,6 @@ describe('sessionAccountToSessionData', () => {
   })
 })
 
-function makeAccount(overrides: Partial<SessionAccount> = {}): SessionAccount {
-  return {
-    service: SERVICE,
-    did: DID,
-    handle: HANDLE,
-    email: 'alice@example.com',
-    emailConfirmed: true,
-    emailAuthFactor: false,
-    refreshJwt: 'refresh-jwt',
-    accessJwt: 'access-jwt',
-    signupQueued: false,
-    active: true,
-    status: undefined,
-    pdsUrl: undefined,
-    isSelfHosted: false,
-    ...overrides,
-  }
-}
-
 describe('createSessionBundleFromStoredAccount', () => {
   it('builds a bridge agent over one session', () => {
     const result = createSessionBundleFromStoredAccount(
@@ -400,59 +403,6 @@ describe('createSessionBundleFromStoredAccount', () => {
   })
 })
 
-/**
- * Build a mock `fetch` that returns canned XRPC responses keyed by the last
- * path segment (nsid). `refreshSession` returns fresh tokens; `getSession`
- * echoes the account; anything else returns an empty 200.
- */
-function makeMockFetch(
-  overrides: Record<
-    string,
-    (url: string, init: RequestInit) => Response | Promise<Response>
-  > = {},
-) {
-  const json = (body: unknown, status = 200) =>
-    new Response(JSON.stringify(body), {
-      status,
-      headers: {'content-type': 'application/json'},
-    })
-  const fetchMock = jest.fn(
-    async (input: URL | string, init: RequestInit = {}): Promise<Response> => {
-      const url = input instanceof URL ? input.href : input
-      const nsid = url.split('/xrpc/')[1]?.split('?')[0]
-      const handler = nsid ? overrides[nsid] : undefined
-      if (handler) {
-        return handler(url, init)
-      }
-      if (nsid === 'com.atproto.server.refreshSession') {
-        return json({
-          accessJwt: 'access-jwt-2',
-          refreshJwt: 'refresh-jwt-2',
-          handle: HANDLE,
-          did: DID,
-          active: true,
-        })
-      }
-      if (nsid === 'com.atproto.server.getSession') {
-        return json({
-          did: DID,
-          handle: HANDLE,
-          email: 'alice@example.com',
-          emailConfirmed: true,
-          active: true,
-        })
-      }
-      return json({})
-    },
-  )
-  return fetchMock
-}
-
-/** Cast a jest fetch mock to the `fetch` type PasswordSession options expect. */
-function asFetch(mock: ReturnType<typeof makeMockFetch>): typeof fetch {
-  return mock as unknown as typeof fetch
-}
-
 describe('makeSessionHooks arm-latch + event mapping', () => {
   /*
    * The hooks read neither `this` (the PasswordSession) nor their data
@@ -770,13 +720,13 @@ describe('PasswordSession lifecycle over mocked fetch', () => {
 })
 
 /*
- * `useSessionApi().refreshSession()` is a thin wrapper over
- * `PasswordSession.refresh()`: on success the armed hooks dispatch exactly one
- * 'update' event and the returned snapshot reflects the refreshed data;
- * rejections propagate. We exercise the auth-core mechanics that the callback
- * relies on (a full provider render is out of scope for a unit test).
+ * A refresh through a bundle's armed hooks: the app has no `refreshSession` api
+ * of its own, so every rotation the reducer sees originates here, in
+ * `PasswordSession.refresh()`. On success the armed hooks dispatch exactly one
+ * 'update' event and the post-refresh snapshot carries the rotated tokens;
+ * rejections propagate to the caller.
  */
-describe('refreshSession semantics', () => {
+describe('PasswordSession.refresh through armed hooks', () => {
   it('refresh() resolves updated data and the armed hooks dispatch exactly one update', async () => {
     const fetchMock = makeMockFetch()
     const onSessionChange =
@@ -808,7 +758,7 @@ describe('refreshSession semantics', () => {
     expect(onSessionChange).toHaveBeenCalledTimes(1)
     expect(onSessionChange.mock.calls[0][2]).toBe('update')
 
-    /* the callback's return value is the post-refresh SessionAccount snapshot */
+    /* the post-refresh SessionAccount snapshot carries the rotated tokens */
     const snapshot = sessionDataToSessionAccount(
       session.session,
       session.session.service,
@@ -833,6 +783,30 @@ describe('refreshSession semantics', () => {
   })
 })
 
+/**
+ * Load a fresh factory graph whose network leaf captures `fetch`.
+ *
+ * `session-core`'s network leaf reads `globalThis.fetch` at module load, and
+ * that captured fetch is what `PasswordSession`'s auto-refresh routes through,
+ * so the module has to be re-required after the override is in place.
+ */
+async function withFreshFactory(
+  fetch: typeof globalThis.fetch,
+  run: (core: typeof import('../session-core')) => Promise<void>,
+) {
+  const realFetch = globalThis.fetch
+  globalThis.fetch = fetch
+  try {
+    await jest.isolateModulesAsync(async () => {
+      const core =
+        require('../session-core') as typeof import('../session-core')
+      await run(core)
+    })
+  } finally {
+    globalThis.fetch = realFetch
+  }
+}
+
 /*
  * The resume/login factories must snapshot the returned account after
  * the prep awaits, not before. A 401 during prep triggers PasswordSession's
@@ -849,24 +823,6 @@ describe('refreshSession semantics', () => {
  * captured fetch is what PasswordSession's auto-refresh routes through.
  */
 describe('factory account snapshot after preparation', () => {
-  /** Load a fresh factory graph whose network leaf captures `fetch`. */
-  async function withFreshFactory(
-    fetch: typeof globalThis.fetch,
-    run: (core: typeof import('../session-core')) => Promise<void>,
-  ) {
-    const realFetch = globalThis.fetch
-    globalThis.fetch = fetch
-    try {
-      await jest.isolateModulesAsync(async () => {
-        const core =
-          require('../session-core') as typeof import('../session-core')
-        await run(core)
-      })
-    } finally {
-      globalThis.fetch = realFetch
-    }
-  }
-
   beforeEach(() => {
     mockConfigureModerationForAccount.mockReset()
     mockPrefetchAgeAssuranceServerData.mockReset()
@@ -925,3 +881,147 @@ describe('factory account snapshot after preparation', () => {
     })
   })
 })
+
+/*
+ * Preparation is the window between building the bundle and arming its hooks.
+ * The session is live but its events are swallowed, so a session that dies in
+ * here would otherwise leave the app holding a bundle that looks signed in and
+ * can only make unauthenticated requests, with nothing left to log it out.
+ * Both failure modes must therefore dispose the bundle and reject.
+ */
+describe('a session destroyed or rejected during preparation', () => {
+  beforeEach(() => {
+    mockConfigureModerationForAccount.mockReset()
+    mockPrefetchAgeAssuranceServerData.mockReset()
+  })
+
+  it('resume: rejects with the revoked-during-prep error and disposes the bundle', async () => {
+    /*
+     * A revoked refresh token: the session's own refresh during prep gets a
+     * declared invalid-token error, which destroys it. `logout()` is the only
+     * way to drive a session to `destroyed` from outside, and it takes the same
+     * `deleteSession` -> onDeleted -> destroyed path the real 401 rescue does.
+     */
+    let capturedAgent: BskyAppAgent | undefined
+    mockConfigureModerationForAccount.mockImplementationOnce(
+      (agent: unknown) => {
+        capturedAgent = agent as BskyAppAgent
+      },
+    )
+    mockPrefetchAgeAssuranceServerData.mockImplementationOnce(async () => {
+      await capturedAgent!.logout()
+    })
+    const fetchMock = makeMockFetch()
+
+    await withFreshFactory(asFetch(fetchMock), async core => {
+      /*
+       * The clean error, not PasswordSession's opaque `Logged out` getter
+       * throw, which is what a naive `snapshot()` on a destroyed session would
+       * surface.
+       */
+      await expect(
+        core.createSessionBundleAndResume(
+          makeAccount({accessJwt: 'valid-access-jwt'}),
+          jest.fn(),
+        ),
+      ).rejects.toThrow('Session was revoked while it was being prepared')
+
+      /* the bundle the caller never received reads as logged out */
+      expect(capturedAgent!.session).toBe(undefined)
+    })
+  })
+
+  it('resume: a prep rejection propagates and disposes the bundle', async () => {
+    let capturedAgent: BskyAppAgent | undefined
+    mockConfigureModerationForAccount.mockImplementationOnce(
+      (agent: unknown) => {
+        capturedAgent = agent as BskyAppAgent
+      },
+    )
+    mockPrefetchAgeAssuranceServerData.mockImplementationOnce(() =>
+      Promise.reject(new Error('prefetch blew up')),
+    )
+    const fetchMock = makeMockFetch()
+
+    await withFreshFactory(asFetch(fetchMock), async core => {
+      await expect(
+        core.createSessionBundleAndResume(
+          makeAccount({accessJwt: 'valid-access-jwt'}),
+          jest.fn(),
+        ),
+      ).rejects.toThrow('prefetch blew up')
+
+      /* the still-live session was disposed rather than left refreshing */
+      expect(capturedAgent!.session).toBe(undefined)
+    })
+  })
+
+  it('finishPreparation disposes and rethrows without running the snapshot', async () => {
+    const hooks = makeSessionHooks(
+      jest.fn(),
+      () => bundle,
+      () => DID,
+    )
+    const session = new PasswordSession(
+      sessionAccountToSessionData(makeAccount()),
+      {...hooks, fetch: asFetch(makeMockFetch())},
+    )
+    const bundle = buildBundle(session)
+    registerBundleKillSwitch(bundle, hooks.kill)
+    const snapshot = jest.fn(() => 'never')
+
+    await expect(
+      finishPreparation(bundle, Promise.reject(new Error('nope')), snapshot),
+    ).rejects.toThrow('nope')
+
+    expect(snapshot).not.toHaveBeenCalled()
+    expect(bundle.agent.session).toBe(undefined)
+  })
+})
+
+/*
+ * A hook must never throw: PasswordSession awaits its hooks inside the
+ * assignment to its internal session promise, so an escaping throw would leave
+ * that promise permanently rejected - every later request fails, while the
+ * session is never marked destroyed, so disposeBundle cannot even see that the
+ * bundle is dead.
+ */
+describe('a throwing onSessionChange does not brick the session', () => {
+  beforeEach(() => {
+    mockLoggerError.mockClear()
+  })
+
+  it('reports through logger.error and leaves the session usable', async () => {
+    const fetchMock = makeMockFetch()
+    const onSessionChange = jest.fn(() => {
+      throw new Error('reducer side effect exploded')
+    })
+    let bundle!: SessionBundle
+    const hooks = makeSessionHooks(
+      onSessionChange,
+      () => bundle,
+      () => DID,
+    )
+    const session = new PasswordSession(
+      sessionAccountToSessionData(makeAccount()),
+      {...hooks, fetch: asFetch(fetchMock)},
+    )
+    bundle = buildBundle(session)
+    hooks.arm()
+
+    await session.refresh()
+
+    expect(onSessionChange).toHaveBeenCalledTimes(1)
+    expect(mockLoggerError).toHaveBeenCalledTimes(1)
+    expect(mockLoggerError.mock.calls[0][1]).toEqual({
+      message: "session: onSessionChange threw for a 'update' event",
+    })
+
+    /* the session still committed the rotation, and can still refresh again */
+    expect(session.session.accessJwt).toBe('access-jwt-2')
+    await expect(session.refresh()).resolves.toBeDefined()
+    await expect(
+      session.fetchHandler('/xrpc/app.bsky.actor.getProfile', {}),
+    ).resolves.toBeDefined()
+  })
+})
diff --git a/src/state/session/__tests__/session-test.ts b/src/state/session/__tests__/session-test.ts
index c084e3dc08..9cb2db6a59 100644
--- a/src/state/session/__tests__/session-test.ts
+++ b/src/state/session/__tests__/session-test.ts
@@ -22,6 +22,18 @@ jest.mock('#/lib/notifications/notifications', () => ({
     return Promise.resolve()
   },
 }))
+/*
+ * The logout and account-removal reducer cases fire a push-token side effect
+ * whose first step, `createTemporaryAgentsAndResume`, builds real `AtpAgent`s
+ * and resumes them over the real network. Under jest that request outlives the
+ * suite: it rejects after teardown, and the resulting `logger.error` reaches
+ * for `nanoid` in an environment that no longer has it, failing whichever suite
+ * happens to be running at that moment. Stubbing the module keeps the side
+ * effect synchronous and offline.
+ */
+jest.mock('../util', () => ({
+  createTemporaryAgentsAndResume: () => Promise.resolve([]),
+}))
 
 // Reuse a bundle within each test: session events are scoped by bundle identity.
 function makeBundle(service: string) {