diff --git a/src/main/broker.ts b/src/main/broker.ts
index 51db7ebe..62e199ea 100644
--- a/src/main/broker.ts
+++ b/src/main/broker.ts
@@ -1339,7 +1339,8 @@ export class BrokerManager {
     cwd: string,
     name: string,
     win: BrowserWindow,
-    channels: string[] = []
+    channels: string[] = [],
+    workspaceKey?: string
   ): Promise<boolean> {
     const normalizedProjectId = projectId.trim()
     if (!normalizedProjectId) {
@@ -1380,7 +1381,7 @@ export class BrokerManager {
     }
 
     const startBroker = async (): Promise<boolean> => {
-      const explicitWorkspaceKey = process.env.AGENT_RELAY_WORKSPACE_KEY?.trim() || undefined
+      const explicitWorkspaceKey = workspaceKey?.trim() || process.env.AGENT_RELAY_WORKSPACE_KEY?.trim() || undefined
       const existingClient = await this.connectExistingBroker(normalizedProjectId, cwd, explicitWorkspaceKey)
       if (existingClient) {
         const eventStreamGeneration = this.nextEventStreamGeneration()
@@ -1617,6 +1618,37 @@ export class BrokerManager {
     return { removed }
   }
 
+  /**
+   * Tear down this project's current broker session(s) and start a fresh
+   * local broker pinned to an existing workspace key, so this Pear instance
+   * joins another instance's workspace instead of creating its own.
+   */
+  async joinWorkspace(
+    projectId: string,
+    cwd: string,
+    name: string,
+    win: BrowserWindow,
+    channels: string[] = [],
+    workspaceKey: string
+  ): Promise<boolean> {
+    const normalizedProjectId = projectId.trim()
+    if (!normalizedProjectId) {
+      throw new Error('Project id is required')
+    }
+    const trimmedKey = workspaceKey.trim()
+    if (!trimmedKey) {
+      throw new Error('Workspace key is required')
+    }
+    assertDirectory(cwd, 'Project path')
+    // A start already in flight for this project (e.g. the initial project
+    // open) would otherwise race start()'s in-flight-reuse path below and
+    // silently keep the broker on the old/first-requested key.
+    const inFlightStart = this.startPromises.get(normalizedProjectId)
+    if (inFlightStart) await inFlightStart.catch(() => undefined)
+    await this.shutdown(normalizedProjectId)
+    return this.start(normalizedProjectId, cwd, name, win, channels, trimmedKey)
+  }
+
   /**
    * The local broker creates the project's relay workspace; its workspace_key
    * is what cloud sandbox brokers must join so local and cloud agents share
diff --git a/src/main/ipc-handlers.ts b/src/main/ipc-handlers.ts
index ed4f80ff..876ce7f5 100644
--- a/src/main/ipc-handlers.ts
+++ b/src/main/ipc-handlers.ts
@@ -650,6 +650,27 @@ export function registerIpcHandlers(): void {
     await brokerManager.syncChannels(projectId, channels)
   })
 
+  ipcMain.handle('broker:join-workspace', async (
+    event,
+    projectId: string,
+    cwd: string,
+    name: string,
+    channels: string[] | undefined,
+    workspaceKey: string
+  ) => {
+    const win = BrowserWindow.fromWebContents(event.sender)
+    if (!win) throw new Error('No window')
+    if (!isDirectory(cwd)) {
+      throw new Error(`Project path no longer exists: ${cwd}`)
+    }
+    const started = await brokerManager.joinWorkspace(projectId, cwd, name, win, channels, workspaceKey)
+    if (started) {
+      void integrationsManager.notifyAgentState(projectId).catch((error) => {
+        console.warn('[integrations] Failed to notify agents after workspace join:', error instanceof Error ? error.message : String(error))
+      })
+    }
+  })
+
   ipcMain.handle('broker:auto-fix-runtime', async (
     event,
     projectId: string,
diff --git a/src/preload/index.ts b/src/preload/index.ts
index 46b0906e..cbf4f52d 100644
--- a/src/preload/index.ts
+++ b/src/preload/index.ts
@@ -225,6 +225,8 @@ const api = {
       invoke<boolean>('broker:start', projectId, cwd, name, channels),
     syncChannels: (projectId: string, channels: string[]) =>
       invoke<void>('broker:sync-channels', projectId, channels),
+    joinWorkspace: (projectId: string, cwd: string, name: string, channels: string[] | undefined, workspaceKey: string) =>
+      invoke<boolean>('broker:join-workspace', projectId, cwd, name, channels, workspaceKey),
     autoFixRuntime: (
       projectId: string,
       cwd: string,
diff --git a/src/renderer/src/components/broker/BrokerDetailsPage.tsx b/src/renderer/src/components/broker/BrokerDetailsPage.tsx
index 3d2dfbd3..dbf58070 100644
--- a/src/renderer/src/components/broker/BrokerDetailsPage.tsx
+++ b/src/renderer/src/components/broker/BrokerDetailsPage.tsx
@@ -1,5 +1,5 @@
 import type React from 'react'
-import { useCallback, useEffect, useMemo, useState } from 'react'
+import { useCallback, useEffect, useMemo, useRef, useState } from 'react'
 import {
   Activity,
   AlertCircle,
@@ -9,6 +9,7 @@ import {
   Copy,
   KeyRound,
   List,
+  LogOut,
   MessageSquare,
   RefreshCw,
   Server,
@@ -840,6 +841,108 @@ function BrokerEventFeed({
   )
 }
 
+function JoinWorkspaceControl({
+  project,
+  joining,
+  joinError,
+  onJoin,
+  onDismissError
+}: {
+  project?: Project
+  joining?: boolean
+  joinError?: string
+  onJoin: (project: Project, workspaceKey: string) => void
+  onDismissError?: (project: Project) => void
+}): React.ReactNode {
+  const [open, setOpen] = useState(false)
+  const [key, setKey] = useState('')
+  const wasJoining = useRef(false)
+
+  useEffect(() => {
+    // Auto-close and reset once a join finishes without leaving an error —
+    // otherwise the form stays open with the submitted key and no feedback
+    // that the join actually succeeded.
+    if (wasJoining.current && !joining && !joinError) {
+      setOpen(false)
+      setKey('')
+    }
+    wasJoining.current = Boolean(joining)
+  }, [joining, joinError])
+
+  if (!project) return null
+
+  const submit = (): void => {
+    const trimmed = key.trim()
+    if (!trimmed) return
+    onJoin(project, trimmed)
+  }
+
+  const close = (): void => {
+    setOpen(false)
+    setKey('')
+    onDismissError?.(project)
+  }
+
+  if (!open) {
+    return (
+      <button
+        type="button"
+        onClick={() => {
+          onDismissError?.(project)
+          setOpen(true)
+        }}
+        className="inline-flex items-center gap-2 rounded-md border border-[var(--pear-border-subtle)] px-3 py-1.5 text-sm text-[var(--pear-text-dim)] hover:border-[var(--pear-accent-dim)] hover:bg-[var(--pear-bg-surface-hover)] hover:text-[var(--pear-text)]"
+      >
+        <LogOut size={14} />
+        <span>Close this workspace and join new one</span>
+      </button>
+    )
+  }
+
+  return (
+    <form
+      className="rounded-lg border border-[var(--pear-border-subtle)] bg-[var(--pear-bg-raised)] p-3"
+      onSubmit={(event) => {
+        event.preventDefault()
+        submit()
+      }}
+    >
+      <p className="mb-2 text-[11px] text-[var(--pear-text-faint)]">
+        Paste the workspace key from another Pear instance&apos;s Agent Relay Status page. This closes the
+        current broker session for this project and reconnects it to that workspace.
+      </p>
+      <div className="flex flex-wrap items-center gap-2">
+        <input
+          type="text"
+          value={key}
+          onChange={(event) => setKey(event.target.value)}
+          placeholder="Workspace key"
+          disabled={joining}
+          autoFocus
+          className="min-w-0 flex-1 rounded-md border border-[var(--pear-border-subtle)] bg-[var(--pear-bg)] px-2 py-1.5 font-mono text-[12px] text-[var(--pear-text)] outline-none focus:border-[var(--pear-accent-dim)]"
+        />
+        <button
+          type="submit"
+          disabled={joining || !key.trim()}
+          className="inline-flex items-center gap-2 rounded-md border border-[var(--pear-accent-dim)] bg-[var(--pear-accent)]/10 px-3 py-1.5 text-sm text-[var(--pear-accent-bright)] hover:bg-[var(--pear-accent)]/15 disabled:cursor-wait disabled:opacity-60"
+        >
+          {joining ? <RefreshCw size={14} className="animate-spin" /> : null}
+          <span>{joining ? 'Joining' : 'Join workspace'}</span>
+        </button>
+        <button
+          type="button"
+          onClick={close}
+          disabled={joining}
+          className="rounded-md border border-[var(--pear-border-subtle)] px-3 py-1.5 text-sm text-[var(--pear-text-dim)] hover:bg-[var(--pear-bg-surface-hover)]"
+        >
+          Cancel
+        </button>
+      </div>
+      {joinError && <p className="mt-2 text-sm text-[var(--pear-red)]">{joinError}</p>}
+    </form>
+  )
+}
+
 function BrokerCard({
   broker,
   projectName,
@@ -848,7 +951,11 @@ function BrokerCard({
   project,
   fixing,
   fixError,
-  onAutoFix
+  onAutoFix,
+  joining,
+  joinError,
+  onJoinWorkspace,
+  onDismissJoinError
 }: {
   broker: BrokerDetails
   projectName: string
@@ -858,6 +965,10 @@ function BrokerCard({
   fixing?: boolean
   fixError?: string
   onAutoFix?: (project: Project, entry: BrokerErrorEntry) => void
+  joining?: boolean
+  joinError?: string
+  onJoinWorkspace?: (project: Project, workspaceKey: string) => void
+  onDismissJoinError?: (project: Project) => void
 }): React.ReactNode {
   const Icon = broker.kind === 'cloud' ? Cloud : Server
 
@@ -904,6 +1015,16 @@ function BrokerCard({
       <div className="space-y-5 p-5">
         <BrokerMetadataSummary broker={broker} />
 
+        {project && onJoinWorkspace && (
+          <JoinWorkspaceControl
+            project={project}
+            joining={joining}
+            joinError={joinError}
+            onJoin={onJoinWorkspace}
+            onDismissError={onDismissJoinError}
+          />
+        )}
+
         <div>
           <div className="mb-3 flex items-center gap-2">
             <KeyRound size={15} className="text-[var(--pear-accent)]" />
@@ -975,6 +1096,8 @@ export function BrokerDetailsPage(): React.ReactNode {
   const [detailsError, setDetailsError] = useState<string | null>(null)
   const [autoFixingProjectId, setAutoFixingProjectId] = useState<string | null>(null)
   const [autoFixErrors, setAutoFixErrors] = useState<Record<string, string>>({})
+  const [joiningProjectId, setJoiningProjectId] = useState<string | null>(null)
+  const [joinErrors, setJoinErrors] = useState<Record<string, string>>({})
 
   const pageProjectId = activeBrokerTabProjectId || activeProjectId || undefined
   const pageProjectName = pageProjectId ? getProjectName(projects, pageProjectId) : 'All projects'
@@ -1087,6 +1210,47 @@ export function BrokerDetailsPage(): React.ReactNode {
     }
   }, [loadBrokerDetails])
 
+  const handleJoinWorkspace = useCallback(async (project: Project, workspaceKey: string): Promise<void> => {
+    const root = getDefaultProjectRoot(project)
+    if (!root?.pathExists) {
+      setJoinErrors((errors) => ({
+        ...errors,
+        [project.id]: `Project path no longer exists: ${root?.path || project.rootPath}`
+      }))
+      return
+    }
+
+    setJoiningProjectId(project.id)
+    setJoinErrors((errors) => {
+      const { [project.id]: _removed, ...remaining } = errors
+      return remaining
+    })
+    try {
+      await pear.broker.joinWorkspace(
+        project.id,
+        root.path,
+        getProjectBrokerName(project),
+        project.channels,
+        workspaceKey
+      )
+      await loadBrokerDetails()
+    } catch (err) {
+      setJoinErrors((errors) => ({
+        ...errors,
+        [project.id]: err instanceof Error ? err.message : String(err)
+      }))
+    } finally {
+      setJoiningProjectId(null)
+    }
+  }, [loadBrokerDetails])
+
+  const handleDismissJoinError = useCallback((project: Project): void => {
+    setJoinErrors((errors) => {
+      const { [project.id]: _removed, ...remaining } = errors
+      return remaining
+    })
+  }, [])
+
   useEffect(() => {
     void loadBrokerDetails()
   }, [loadBrokerDetails])
@@ -1145,6 +1309,10 @@ export function BrokerDetailsPage(): React.ReactNode {
                     fixing={autoFixingProjectId === broker.projectId}
                     fixError={autoFixErrors[broker.projectId]}
                     onAutoFix={(project, entry) => void handleAutoFix(project, entry)}
+                    joining={joiningProjectId === broker.projectId}
+                    joinError={joinErrors[broker.projectId]}
+                    onJoinWorkspace={(project, workspaceKey) => void handleJoinWorkspace(project, workspaceKey)}
+                    onDismissJoinError={handleDismissJoinError}
                   />
                 ))}
                 {unmatchedProjectErrorGroups.map(([projectId, entries]) => (
diff --git a/src/renderer/src/lib/ipc-mock.ts b/src/renderer/src/lib/ipc-mock.ts
index ee7d6ad0..162ac205 100644
--- a/src/renderer/src/lib/ipc-mock.ts
+++ b/src/renderer/src/lib/ipc-mock.ts
@@ -875,6 +875,19 @@ export const pearMock: PearAPI = {
       const project = state.projects.find((entry) => entry.id === projectId)
       if (project) project.channels = Array.from(new Set(channels))
     },
+    joinWorkspace: async (
+      projectId: string,
+      _cwd: string,
+      _name: string,
+      _channels: string[] | undefined,
+      workspaceKey: string
+    ) => {
+      if (!workspaceKey.trim()) {
+        throw new Error('Workspace key is required')
+      }
+      emitBrokerStatus({ projectId, status: 'connected' })
+      return true
+    },
     autoFixRuntime: async () => ({ removed: [] }),
     connectCloud: async () => 'mock-cloud',
     spawnAgent: async (projectId: string, input: BrokerSpawnAgentInput): Promise<BrokerSpawnAgentResult> => {
diff --git a/src/shared/types/ipc.ts b/src/shared/types/ipc.ts
index f4711a20..cb082d48 100644
--- a/src/shared/types/ipc.ts
+++ b/src/shared/types/ipc.ts
@@ -912,6 +912,13 @@ export interface PearAPI {
   broker: {
     start: (projectId: string, cwd: string, name: string, channels?: string[]) => Promise<boolean>
     syncChannels: (projectId: string, channels: string[]) => Promise<void>
+    joinWorkspace: (
+      projectId: string,
+      cwd: string,
+      name: string,
+      channels: string[] | undefined,
+      workspaceKey: string
+    ) => Promise<boolean>
     autoFixRuntime: (
       projectId: string,
       cwd: string,