diff --git a/packages/ui/src/sync/DOCUMENTATION.md b/packages/ui/src/sync/DOCUMENTATION.md
index a48479ba..92399850 100644
--- a/packages/ui/src/sync/DOCUMENTATION.md
+++ b/packages/ui/src/sync/DOCUMENTATION.md
@@ -213,10 +213,20 @@ Examples of global-store updates performed in `session-actions.ts`:
 - `createSession()` -> `upsertSession(session)`
 - `updateSessionTitle()` -> `upsertSession(result.data)`
 - `shareSession()` / `unshareSession()` -> `upsertSession(result.data)`
-- `archiveSession()` -> waits for server confirmation, then upserts the archived session
+- `archiveSession()` / `archiveSessions()` -> wait for server confirmation, then upsert each archived session
 - `deleteSession()` -> waits for server confirmation or `404`, then removes the session and its persisted state
 - `moveSessionToDirectory()` -> move the session between directory stores and update the global directory index
 
+Archive callers whose confirmation spans asynchronous SDK calls may capture the
+runtime key at operation start and pass it as `expectedRuntimeKey`. The guarded
+action rechecks that key before every store reconciliation, so a response
+produced by the previous runtime is rejected instead of mutating the current
+runtime's live or global session state. A guarded batch stops at the first
+observed runtime change: sessions the server already confirmed remain archived
+and stay in `archivedIds`, while every ID not confirmed on the captured runtime
+is returned in `failedIds` so existing partial-failure feedback stays truthful.
+Callers that pass no runtime key keep the previous unguarded behavior.
+
 ## The golden rule
 
 When creating a draft in `handleDirectoryEvent`, **only clone the state fields the event will mutate**. Never spread all fields eagerly.
diff --git a/packages/ui/src/sync/session-actions.test.ts b/packages/ui/src/sync/session-actions.test.ts
index cfd4f9f0..0e2bda49 100644
--- a/packages/ui/src/sync/session-actions.test.ts
+++ b/packages/ui/src/sync/session-actions.test.ts
@@ -14,6 +14,7 @@ let sessionShareResult: { data?: unknown; error?: unknown; response?: { status?:
 let sessionUpdateResult: { data?: unknown; error?: unknown; response?: { status?: number } } = {}
 let sessionMessagesResult: { data?: unknown; error?: unknown; response?: { status?: number } } = { data: [] }
 let sessionDeleteError: unknown | null = null
+let beforeSessionUpdateResolve: ((sessionId: string) => void) | null = null
 const globalUpsertedSessions: unknown[] = []
 const globalRemovedSessionIds: string[] = []
 const deletedCleanupIdentities: Array<{ runtimeKey: string; directory: string; sessionId: string }> = []
@@ -145,6 +146,9 @@ mock.module("@/lib/opencode/client", () => ({
     }),
     updateSession: mock((sessionId: string, changes: Record<string, unknown>, directory?: string | null) => {
       replyCalls.push({ method: "session.update", params: { sessionID: sessionId, ...changes, directory } })
+      // Lets a test mutate global runtime state while the SDK call is in flight,
+      // so the action observes the switch only after awaiting the response.
+      beforeSessionUpdateResolve?.(sessionId)
       return Promise.resolve(sessionUpdateResult.data)
     }),
     deleteSession: mock((sessionId: string, directory?: string | null) => {
@@ -368,6 +372,7 @@ describe("confirmed session removal", () => {
     deletedCleanupIdentities.length = 0
     sessionDeleteError = null
     sessionUpdateResult = {}
+    beforeSessionUpdateResolve = null
   })
 
   test("does not remove live or persisted state when delete fails", async () => {
@@ -427,6 +432,86 @@ describe("confirmed session removal", () => {
     expect(source.getState().session).toEqual([])
     expect((globalUpsertedSessions[0] as Session)?.time?.archived).toBe(2)
   })
+
+  test("rejects an archive response that arrives after a runtime switch", async () => {
+    sessionUpdateResult = {
+      data: { id: "session-a", directory: "/test/project", time: { created: 1, archived: 2 } } as Session,
+    }
+    const source = createStore({}, {
+      session: [{ id: "session-a", directory: "/test/project", time: { created: 1 } } as Session],
+    })
+    const { getRuntimeKey, switchRuntimeEndpoint } = await import("../lib/runtime-switch")
+    switchRuntimeEndpoint({ apiBaseUrl: "http://archive-runtime-a.test", runtimeKey: "archive-runtime-a" })
+    beforeSessionUpdateResolve = () => {
+      switchRuntimeEndpoint({ apiBaseUrl: "http://archive-runtime-b.test", runtimeKey: "archive-runtime-b" })
+    }
+    const { archiveSession, setActionRefs } = await import("./session-actions")
+    setActionRefs(mockSdk as unknown as OpencodeClient, createChildStores([["/test/project", source]]), () => "/test/project")
+
+    expect(await archiveSession("session-a", "archive-runtime-a")).toBe(false)
+    expect(getRuntimeKey()).toBe("archive-runtime-b")
+    // The stale response must not reconcile the runtime the user switched to.
+    expect(source.getState().session.map((item) => item.id)).toEqual(["session-a"])
+    expect(globalUpsertedSessions).toEqual([])
+  })
+
+  test("keeps confirmed sessions and fails the rest when the runtime changes mid-batch", async () => {
+    sessionUpdateResult = {
+      data: { id: "session-a", directory: "/test/project", time: { created: 1, archived: 2 } } as Session,
+    }
+    const source = createStore({}, {
+      session: [
+        { id: "session-a", directory: "/test/project", time: { created: 1 } } as Session,
+        { id: "session-b", directory: "/test/project", time: { created: 1 } } as Session,
+        { id: "session-c", directory: "/test/project", time: { created: 1 } } as Session,
+      ],
+    })
+    const { switchRuntimeEndpoint } = await import("../lib/runtime-switch")
+    switchRuntimeEndpoint({ apiBaseUrl: "http://archive-batch-a.test", runtimeKey: "archive-batch-a" })
+    beforeSessionUpdateResolve = (sessionId) => {
+      if (sessionId === "session-b") {
+        switchRuntimeEndpoint({ apiBaseUrl: "http://archive-batch-b.test", runtimeKey: "archive-batch-b" })
+      }
+    }
+    const { archiveSessions, setActionRefs } = await import("./session-actions")
+    setActionRefs(mockSdk as unknown as OpencodeClient, createChildStores([["/test/project", source]]), () => "/test/project")
+
+    const result = await archiveSessions(["session-a", "session-b", "session-c"], {
+      expectedRuntimeKey: "archive-batch-a",
+    })
+
+    // session-a was confirmed before the switch and stays archived; session-b's
+    // response is stale and session-c is never attempted, so both are reported
+    // as failures instead of being silently dropped.
+    expect(result).toEqual({ archivedIds: ["session-a"], failedIds: ["session-b", "session-c"] })
+    expect(source.getState().session.map((item) => item.id)).toEqual(["session-b", "session-c"])
+    expect(globalUpsertedSessions).toHaveLength(1)
+    // session-c must not reach the SDK after the runtime changed.
+    expect(replyCalls.filter((call) => call.method === "session.update").map((call) => call.params.sessionID))
+      .toEqual(["session-a", "session-b"])
+  })
+
+  test("archives every session when the runtime stays stable", async () => {
+    sessionUpdateResult = {
+      data: { id: "session-a", directory: "/test/project", time: { created: 1, archived: 2 } } as Session,
+    }
+    const source = createStore({}, {
+      session: [
+        { id: "session-a", directory: "/test/project", time: { created: 1 } } as Session,
+        { id: "session-b", directory: "/test/project", time: { created: 1 } } as Session,
+      ],
+    })
+    const { getRuntimeKey } = await import("../lib/runtime-switch")
+    const { archiveSessions, setActionRefs } = await import("./session-actions")
+    setActionRefs(mockSdk as unknown as OpencodeClient, createChildStores([["/test/project", source]]), () => "/test/project")
+
+    const result = await archiveSessions(["session-a", "session-b"], {
+      expectedRuntimeKey: getRuntimeKey(),
+    })
+
+    expect(result).toEqual({ archivedIds: ["session-a", "session-b"], failedIds: [] })
+    expect(source.getState().session).toEqual([])
+  })
 })
 
 describe("fetchMessagesForSession startup race", () => {
diff --git a/packages/ui/src/sync/session-actions.ts b/packages/ui/src/sync/session-actions.ts
index c25ecb1e..43e08171 100644
--- a/packages/ui/src/sync/session-actions.ts
+++ b/packages/ui/src/sync/session-actions.ts
@@ -654,15 +654,29 @@ export async function createSession(
   }
 }
 
+/**
+ * True when a caller captured a runtime key before an asynchronous mutation and
+ * that runtime is no longer the active one. Callers pass `undefined` when they
+ * do not participate in runtime-scoped guarding, which keeps the previous
+ * unguarded behavior.
+ */
+function isStaleRuntime(expectedRuntimeKey: string | undefined): boolean {
+  return expectedRuntimeKey !== undefined && getRuntimeKey() !== expectedRuntimeKey
+}
+
 export async function patchSessionMetadata(
   sessionId: string,
   directory: string | null | undefined,
   updater: (metadata: SessionMetadataRecord) => SessionMetadataRecord,
+  expectedRuntimeKey?: string,
 ): Promise<Session> {
+  if (isStaleRuntime(expectedRuntimeKey)) throw new Error("runtime changed")
   const targetDirectory = directory ?? getSessionDirectory(sessionId)
   const current = await opencodeClient.getSession(sessionId, targetDirectory)
+  if (isStaleRuntime(expectedRuntimeKey)) throw new Error("runtime changed")
   const nextMetadata = updater(getSessionMetadata(current))
   const updated = await opencodeClient.updateSession(sessionId, { metadata: nextMetadata }, targetDirectory)
+  if (isStaleRuntime(expectedRuntimeKey)) throw new Error("runtime changed")
   useGlobalSessionsStore.getState().upsertSession(updated)
   const sessionDirectory = (updated as { directory?: string | null }).directory ?? targetDirectory
   if (sessionDirectory) registerSessionDirectory(updated.id, sessionDirectory)
@@ -682,19 +696,26 @@ export async function setContextObligatoryMessage(
   return updated
 }
 
-async function cleanupReviewMetadataBeforeDelete(sessionId: string, directory?: string | null): Promise<void> {
+async function cleanupReviewMetadataBeforeDelete(
+  sessionId: string,
+  directory?: string | null,
+  expectedRuntimeKey?: string,
+): Promise<void> {
+  if (isStaleRuntime(expectedRuntimeKey)) return
   let session: Session
   try {
     session = await opencodeClient.getSession(sessionId, directory ?? getSessionDirectory(sessionId))
   } catch {
     return
   }
+  if (isStaleRuntime(expectedRuntimeKey)) return
   if (!isReviewSession(session)) return
   const originalSessionID = getOriginalSessionID(session)
   if (!originalSessionID) return
   try {
     await patchSessionMetadata(originalSessionID, directory ?? getSessionDirectory(originalSessionID), (metadata) =>
       withoutReviewSessionLink(metadata, sessionId),
+      expectedRuntimeKey,
     )
   } catch (error) {
     const message = error instanceof Error ? error.message : String(error)
@@ -803,12 +824,26 @@ export async function deleteSessionInDirectory(sessionId: string, directory: str
   }
 }
 
-export async function archiveSession(sessionId: string): Promise<boolean> {
+/**
+ * Archive one session.
+ *
+ * `expectedRuntimeKey` is the runtime key the caller captured when the user
+ * confirmed the operation. When it is supplied and the runtime changes, the
+ * action stops and returns `false` without reconciling any store, so a response
+ * produced by the previous runtime cannot mutate the current runtime's live or
+ * global session state. A session the server already archived before the switch
+ * stays archived on that runtime and is re-read from the server the next time
+ * the runtime is loaded.
+ */
+export async function archiveSession(sessionId: string, expectedRuntimeKey?: string): Promise<boolean> {
+  if (isStaleRuntime(expectedRuntimeKey)) return false
   const sessionDirectory = getSessionDirectory(sessionId)
   const archivedAt = Date.now()
   try {
-    await cleanupReviewMetadataBeforeDelete(sessionId, sessionDirectory)
+    await cleanupReviewMetadataBeforeDelete(sessionId, sessionDirectory, expectedRuntimeKey)
+    if (isStaleRuntime(expectedRuntimeKey)) return false
     const archived = await opencodeClient.updateSession(sessionId, { time: { archived: archivedAt } }, sessionDirectory)
+    if (isStaleRuntime(expectedRuntimeKey)) return false
     if (!archived) {
       throw new Error("session.update failed: server did not return the archived session")
     }
@@ -824,6 +859,45 @@ export async function archiveSession(sessionId: string): Promise<boolean> {
   }
 }
 
+export type ArchiveSessionsOptions = {
+  /**
+   * Runtime key captured when the batch was confirmed. When supplied, the batch
+   * stops as soon as the active runtime differs.
+   */
+  expectedRuntimeKey?: string
+}
+
+/**
+ * Archive several sessions sequentially, preserving partial results.
+ *
+ * One failed session never blocks or erases the others: it is reported in
+ * `failedIds` while the remaining IDs are still attempted. When
+ * `expectedRuntimeKey` is supplied and the runtime changes mid-batch, the
+ * already-confirmed sessions stay in `archivedIds` and every ID that was not
+ * confirmed on the captured runtime is reported in `failedIds`, so callers keep
+ * showing the existing partial-failure feedback instead of silently dropping
+ * work.
+ */
+export async function archiveSessions(
+  ids: string[],
+  options?: ArchiveSessionsOptions,
+): Promise<{ archivedIds: string[]; failedIds: string[] }> {
+  const archivedIds: string[] = []
+  const failedIds: string[] = []
+  const expectedRuntimeKey = options?.expectedRuntimeKey
+
+  for (const [index, id] of ids.entries()) {
+    if (isStaleRuntime(expectedRuntimeKey)) {
+      failedIds.push(...ids.slice(index))
+      break
+    }
+    if (await archiveSession(id, expectedRuntimeKey)) archivedIds.push(id)
+    else failedIds.push(id)
+  }
+
+  return { archivedIds, failedIds }
+}
+
 export async function updateSessionTitle(sessionId: string, title: string): Promise<void> {
   const sessionDirectory = getSessionDirectory(sessionId)
   const session = await opencodeClient.updateSession(sessionId, { title }, sessionDirectory)
diff --git a/packages/ui/src/sync/session-ui-store.test.js b/packages/ui/src/sync/session-ui-store.test.js
index 468ff442..5d4dec03 100644
--- a/packages/ui/src/sync/session-ui-store.test.js
+++ b/packages/ui/src/sync/session-ui-store.test.js
@@ -454,3 +454,33 @@ describe('routeMessage skill invocation', () => {
     expect(sendCommandCalls).toHaveLength(0);
   });
 });
+
+describe('archiveSessions option forwarding', () => {
+  let originalUpdateSession;
+  let updateSessionCalls;
+
+  beforeEach(() => {
+    updateSessionCalls = [];
+    originalUpdateSession = opencodeClient.updateSession;
+    opencodeClient.updateSession = (sessionId) => {
+      updateSessionCalls.push(sessionId);
+      return Promise.resolve(null);
+    };
+  });
+
+  afterEach(() => {
+    opencodeClient.updateSession = originalUpdateSession;
+  });
+
+  // The store used to accept an options object and silently drop it, so a
+  // caller-supplied runtime key had no effect. Passing a key that cannot match
+  // the active runtime must abort the batch before any SDK call.
+  test('honors expectedRuntimeKey instead of discarding the options object', async () => {
+    const result = await useSessionUIStore.getState().archiveSessions(['session-x', 'session-y'], {
+      expectedRuntimeKey: 'runtime-that-is-not-active',
+    });
+
+    expect(result).toEqual({ archivedIds: [], failedIds: ['session-x', 'session-y'] });
+    expect(updateSessionCalls).toEqual([]);
+  });
+});
diff --git a/packages/ui/src/sync/session-ui-store.ts b/packages/ui/src/sync/session-ui-store.ts
index 3f136e32..d552029a 100644
--- a/packages/ui/src/sync/session-ui-store.ts
+++ b/packages/ui/src/sync/session-ui-store.ts
@@ -47,6 +47,7 @@ import {
   createSession as createSessionAction,
   deleteSession as deleteSessionAction,
   archiveSession as archiveSessionAction,
+  archiveSessions as archiveSessionsAction,
   updateSessionTitle as updateSessionTitleAction,
   shareSession as shareSessionAction,
   unshareSession as unshareSessionAction,
@@ -56,6 +57,7 @@ import {
   unrevertSession as unrevertSessionAction,
   forkFromMessage as forkFromMessageAction,
   fetchMessagesForSession,
+  type ArchiveSessionsOptions,
 } from "./session-actions"
 import { useInputStore, type SyntheticContextPart } from "./input-store"
 import { useSessionGoalArmStore } from "@/stores/useSessionGoalArmStore"
@@ -323,7 +325,7 @@ export type SessionUIState = {
   deleteSession: (id: string, options?: Record<string, unknown>) => Promise<boolean>
   deleteSessions: (ids: string[], options?: Record<string, unknown>) => Promise<{ deletedIds: string[]; failedIds: string[] }>
   archiveSession: (id: string) => Promise<boolean>
-  archiveSessions: (ids: string[], options?: Record<string, unknown>) => Promise<{ archivedIds: string[]; failedIds: string[] }>
+  archiveSessions: (ids: string[], options?: ArchiveSessionsOptions) => Promise<{ archivedIds: string[]; failedIds: string[] }>
   updateSessionTitle: (sessionId: string, title: string) => Promise<void>
   shareSession: (sessionId: string) => Promise<Session | null>
   unshareSession: (sessionId: string) => Promise<Session | null>
@@ -1304,16 +1306,7 @@ export const useSessionUIStore = create<SessionUIState>()((set, get) => ({
 
   archiveSession: (id) => archiveSessionAction(id),
 
-  archiveSessions: async (ids) => {
-    const archivedIds: string[] = []
-    const failedIds: string[] = []
-    for (const id of ids) {
-      const ok = await archiveSessionAction(id)
-      if (ok) archivedIds.push(id)
-      else failedIds.push(id)
-    }
-    return { archivedIds, failedIds }
-  },
+  archiveSessions: (ids, options) => archiveSessionsAction(ids, options),
 
   // ---------------------------------------------------------------------------
   // updateSessionTitle — calls SDK, SSE event updates child store