diff --git a/src/renderer/src/hooks/useDetectedAgents.host-reconnect.test.tsx b/src/renderer/src/hooks/useDetectedAgents.host-reconnect.test.tsx
new file mode 100644
index 00000000000..791a9f0dee9
--- /dev/null
+++ b/src/renderer/src/hooks/useDetectedAgents.host-reconnect.test.tsx
@@ -0,0 +1,182 @@
+// @vitest-environment happy-dom
+
+import { act, createElement } from 'react'
+import { createRoot, type Root } from 'react-dom/client'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import { useAppStore } from '@/store'
+import { useDetectedAgents, type UseDetectedAgentsResult } from './useDetectedAgents'
+import {
+  MIN_COMPATIBLE_RUNTIME_CLIENT_VERSION,
+  RUNTIME_PROTOCOL_VERSION
+} from '../../../shared/protocol-version'
+import type { PublicKnownRuntimeEnvironment } from '../../../shared/runtime-environments'
+import type { RuntimeStatus } from '../../../shared/runtime-types'
+import { clearRuntimeCompatibilityCacheForTests } from '@/runtime/runtime-rpc-client'
+
+globalThis.IS_REACT_ACT_ENVIRONMENT = true
+
+const runtimeEnvironmentCall = vi.fn()
+const initialAppState = useAppStore.getInitialState()
+const roots: Root[] = []
+let latest: UseDetectedAgentsResult | null = null
+
+function HookProbe(): null {
+  latest = useDetectedAgents({ kind: 'runtime', environmentId: 'env-1' })
+  return null
+}
+
+async function flushEffects(): Promise<void> {
+  await act(async () => {
+    await Promise.resolve()
+    await Promise.resolve()
+  })
+}
+
+async function renderProbe(): Promise<void> {
+  const container = document.createElement('div')
+  document.body.appendChild(container)
+  const root = createRoot(container)
+  roots.push(root)
+  await act(async () => {
+    root.render(createElement(HookProbe))
+  })
+  await flushEffects()
+}
+
+function environment(pairingRevision: number): PublicKnownRuntimeEnvironment {
+  return {
+    id: 'env-1',
+    name: 'Paired host',
+    createdAt: 1,
+    updatedAt: pairingRevision,
+    pairingRevision,
+    lastUsedAt: null,
+    runtimeId: null,
+    endpoints: [],
+    preferredEndpointId: 'host'
+  }
+}
+
+function reply(method: string, result: unknown) {
+  return { id: method, ok: true, result, _meta: { runtimeId: 'remote-runtime' } }
+}
+
+const STATUS = {
+  runtimeId: 'remote-runtime',
+  rendererGraphEpoch: 1,
+  graphStatus: 'ready',
+  authoritativeWindowId: null,
+  liveTabCount: 0,
+  liveLeafCount: 0,
+  runtimeProtocolVersion: RUNTIME_PROTOCOL_VERSION,
+  minCompatibleRuntimeClientVersion: MIN_COMPATIBLE_RUNTIME_CLIENT_VERSION
+}
+
+function mockHost(detect: (call: number, method: string) => Promise<unknown>): () => number {
+  let detectCalls = 0
+  runtimeEnvironmentCall.mockImplementation(({ method }: { method: string }) => {
+    if (method === 'status.get') {
+      return Promise.resolve(reply(method, STATUS))
+    }
+    detectCalls += 1
+    return detect(detectCalls, method)
+  })
+  return () => detectCalls
+}
+
+beforeEach(() => {
+  clearRuntimeCompatibilityCacheForTests()
+  useAppStore.setState(initialAppState, true)
+  latest = null
+  runtimeEnvironmentCall.mockReset()
+  Object.defineProperty(globalThis.window, 'api', {
+    configurable: true,
+    value: {
+      preflight: { detectAgents: vi.fn(), detectRemoteAgents: vi.fn(), refreshAgents: vi.fn() },
+      runtimeEnvironments: { call: runtimeEnvironmentCall },
+      platform: { get: () => ({ platform: 'win32' }) }
+    }
+  })
+})
+
+afterEach(async () => {
+  for (const root of roots) {
+    await act(async () => {
+      root.unmount()
+    })
+  }
+  roots.length = 0
+})
+
+const LIVE_STATUS: RuntimeStatus = { ...STATUS, graphStatus: 'ready' }
+
+function setHostContact(entry: { live: boolean; hostContactEpoch: number }): void {
+  const runtimeStatusByEnvironmentId = new Map(useAppStore.getState().runtimeStatusByEnvironmentId)
+  runtimeStatusByEnvironmentId.set('env-1', {
+    status: entry.live ? LIVE_STATUS : null,
+    checkedAt: entry.hostContactEpoch,
+    connectionGeneration: 1,
+    hostContactEpoch: entry.hostContactEpoch
+  })
+  useAppStore.setState({ runtimeStatusByEnvironmentId })
+}
+
+describe('useDetectedAgents when the runtime host reconnects', () => {
+  it('re-lists agents once contact returns after a failed probe, and not while the host is down', async () => {
+    let hostUp = false
+    const detectCalls = mockHost((_call, method) =>
+      hostUp
+        ? Promise.resolve(reply(method, ['codex']))
+        : Promise.reject(new Error('The WSL host isn’t connected.'))
+    )
+    useAppStore.getState().setRuntimeEnvironments([environment(1)])
+    setHostContact({ live: false, hostContactEpoch: 1 })
+    await renderProbe()
+    await flushEffects()
+    expect(latest?.detectionFailed).toBe(true)
+    const failedCalls = detectCalls()
+
+    // A down host is not probed again: re-listing must never boot a stopped distro.
+    await act(async () => {
+      setHostContact({ live: false, hostContactEpoch: 2 })
+    })
+    await flushEffects()
+    expect(detectCalls()).toBe(failedCalls)
+    expect(latest?.detectionFailed).toBe(true)
+
+    hostUp = true
+    await act(async () => {
+      setHostContact({ live: true, hostContactEpoch: 3 })
+    })
+    await flushEffects()
+    await flushEffects()
+
+    expect(detectCalls()).toBe(failedCalls + 1)
+    expect(latest?.detectedIds).toEqual(['codex'])
+    expect(latest?.detectionFailed).toBe(false)
+  })
+
+  it('re-lists after a reconnect even when the failed probe ran while contact looked live', async () => {
+    let hostUp = false
+    const detectCalls = mockHost((_call, method) =>
+      hostUp
+        ? Promise.resolve(reply(method, ['codex']))
+        : Promise.reject(new Error('runtime disconnected'))
+    )
+    useAppStore.getState().setRuntimeEnvironments([environment(1)])
+    setHostContact({ live: true, hostContactEpoch: 1 })
+    await renderProbe()
+    await flushEffects()
+    expect(latest?.detectionFailed).toBe(true)
+
+    hostUp = true
+    await act(async () => {
+      setHostContact({ live: true, hostContactEpoch: 2 })
+    })
+    await flushEffects()
+    await flushEffects()
+
+    expect(detectCalls()).toBeGreaterThanOrEqual(2)
+    expect(latest?.detectedIds).toEqual(['codex'])
+  })
+})
diff --git a/src/renderer/src/hooks/useDetectedAgents.ts b/src/renderer/src/hooks/useDetectedAgents.ts
index 708018fc8ee..92b8cdd3c8d 100644
--- a/src/renderer/src/hooks/useDetectedAgents.ts
+++ b/src/renderer/src/hooks/useDetectedAgents.ts
@@ -1,5 +1,6 @@
 import { useCallback, useEffect, useRef } from 'react'
 import { useAppStore } from '@/store'
+import { runtimeHostContactForEntry } from '../../../shared/runtime-host-contact'
 import type { TuiAgent } from '../../../shared/tui-agent'
 import { getRuntimeAgentInventoryKey } from '@/store/slices/runtime-agent-inventory-key'
 
@@ -75,6 +76,21 @@ export function useDetectedAgents(
     return environment ? (environment.pairingRevision ?? environment.createdAt) : undefined
   })
 
+  // Why: a probe that failed while the host was down must re-run once contact returns, and only then.
+  // 'down' only when the host's status says so; a never-asked host is still probed as before.
+  const runtimeContactEpoch = useAppStore((s) => {
+    if (targetKind !== 'runtime' || !targetId) {
+      return null
+    }
+    const entry = s.runtimeStatusByEnvironmentId.get(targetId)
+    if (!entry) {
+      return null
+    }
+    return runtimeHostContactForEntry(entry).verdict === 'live'
+      ? `${entry.connectionGeneration ?? 0}:${entry.hostContactEpoch ?? 0}`
+      : 'down'
+  })
+
   const detectedIds = useAppStore((s) => {
     if (isUnknown) {
       return null
@@ -167,8 +183,14 @@ export function useDetectedAgents(
         void state.ensureRemoteDetectedAgents(targetId)
       }
     } else if (targetKind === 'runtime' && targetId) {
+      const failedWhileOffline =
+        runtimeContactEpoch === 'down' &&
+        recordKey !== null &&
+        state.runtimeAgentInventoryOutcome(recordKey) === 'failed'
       if (detectedIds === null) {
-        void state.ensureRuntimeDetectedAgents(targetId, runtimeWorktreeId)
+        if (!failedWhileOffline) {
+          void state.ensureRuntimeDetectedAgents(targetId, runtimeWorktreeId)
+        }
       } else if (isNewRemoteTarget && detectedIds.length > 0) {
         // Refresh once when a new launch surface observes a host; cached inventory may predate installs.
         void state.refreshRuntimeDetectedAgents(targetId, runtimeWorktreeId)
@@ -186,7 +208,9 @@ export function useDetectedAgents(
     targetKind,
     targetId,
     remoteTargetKey,
+    recordKey,
     pairingRevision,
+    runtimeContactEpoch,
     detectedIds,
     localProbePending,
     localWorktreeId,