diff --git a/src/main/acp/acp-launch-specs.ts b/src/main/acp/acp-launch-specs.ts
index abd489e8633..7083bef1115 100644
--- a/src/main/acp/acp-launch-specs.ts
+++ b/src/main/acp/acp-launch-specs.ts
@@ -15,6 +15,7 @@ import { isStableCliVersionFrom, isStableCliVersionOnLine } from '../agent-cli-v
 import type { TuiAgent } from '../../shared/tui-agent'
 import type { AgentSessionModelOption } from '../../shared/agent-session-wire'
 import type { InitializeResponse } from './generated/acp-protocol.generated'
+import type { ManagedRuntime } from '../node-runtime/managed-runtime-release'
 import { readGrokModelCatalog } from './acp-dialects/grok-model-catalog'
 import {
   OPENCODE_MODEL_LISTING_ARGS,
@@ -88,6 +89,9 @@ export type AcpLaunchSpec = {
   supportsVersion?(version: string): boolean
   /** Where the agent installs its own binary, searched after PATH. */
   installDirectories(input: { env: Readonly<Record<string, string>>; homePath: string }): string[]
+  /** A pinned copy Orca installs under its data folder when the person asks, searched last; a
+   *  start never installs it. A spec with one names no `supportsVersion`. */
+  managedRuntime?: ManagedRuntime
   /** Images go to the agent when it also advertises them; off sends text prompts only. */
   imagePrompts?: true
   /** The agent compacts its conversation when sent `/compact` as a prompt; off hides `/compact`. */
diff --git a/src/main/acp/acp-model-catalog-probe.test.ts b/src/main/acp/acp-model-catalog-probe.test.ts
index a166a143a33..7afa57e763a 100644
--- a/src/main/acp/acp-model-catalog-probe.test.ts
+++ b/src/main/acp/acp-model-catalog-probe.test.ts
@@ -69,6 +69,7 @@ function scriptedGrok(initializeMeta: Record<string, unknown>): {
     closed: () => closes,
     deps: {
       resolveEnvironment: async () => ({ PATH: '/usr/bin', HOME: '/home/user' }),
+      dataDirectory: '/orca-data',
       resolveLaunchEnv: () => ({ XAI_API_KEY: 'from-settings' }),
       resolveCommand: () => '/opt/grok/bin/grok',
       homePath: '/home/user',
@@ -155,6 +156,7 @@ describe('ACP model catalog probes', () => {
     const connect = vi.fn()
     const probe = createAcpModelCatalogProbe(OPENCODE, {
       resolveEnvironment: async () => ({ PATH: '/usr/bin', HOME: '/home/user' }),
+      dataDirectory: '/orca-data',
       resolveCommand: () => '/opt/opencode/bin/opencode',
       probeVersion: async () => true,
       homePath: '/home/user',
@@ -180,6 +182,7 @@ describe('ACP model catalog probes', () => {
     const runListing = vi.fn()
     const probe = createAcpModelCatalogProbe(OPENCODE, {
       resolveEnvironment: async () => ({ PATH: '/usr/bin' }),
+      dataDirectory: '/orca-data',
       resolveCommand: () => '/opt/opencode/bin/opencode',
       probeVersion: async () => false,
       runListing
diff --git a/src/main/acp/acp-structured-acquire.ts b/src/main/acp/acp-structured-acquire.ts
index 98323a272a1..29f483c5201 100644
--- a/src/main/acp/acp-structured-acquire.ts
+++ b/src/main/acp/acp-structured-acquire.ts
@@ -27,7 +27,7 @@ import type { AcpStructuredConnection } from './acp-structured-connection'
 import { ACP_HANDLE_TRANSPORT, acpAgentName } from './acp-structured-agent-definitions'
 import { AcpStructuredLane, acpLaneChildWorkDelivery } from './acp-structured-lane'
 import { NO_ACP_CHILD_STOPS, probeAcpChildStops } from './acp-structured-child-stop'
-import type { AcpStructuredLaunch } from './acp-structured-launch-resolution'
+import { prepareAcpStructuredLaunch } from './acp-structured-launch-preparation'
 import { AcpStructuredOptions, restoreAcpSessionOptions } from './acp-structured-options'
 import { AcpStructuredPrompts } from './acp-structured-prompts'
 import {
@@ -77,12 +77,7 @@ export async function acquireAcpStructuredSession(input: {
     }
   }
   closedBeforeSpawn()
-  const launch: AcpStructuredLaunch = await deps
-    .resolveLaunch({ identity: acquire.identity, spawnToken: acquire.spawnToken })
-    .catch((error: unknown) => {
-      throw new AgentSessionPreSpawnError(error)
-    })
-  closedBeforeSpawn()
+  const launch = await prepareAcpStructuredLaunch(deps, acquire, closedBeforeSpawn)
   let session: AcpStructuredSession | null = null
   // A slot rather than a `let`: closures read it, and control-flow narrowing cannot see them write.
   const slot: { lane: AcpStructuredLane | null; reattaching: boolean } = {
diff --git a/src/main/acp/acp-structured-host-configured-default.test.ts b/src/main/acp/acp-structured-host-configured-default.test.ts
index f37dbafac6d..22d6fdc73d2 100644
--- a/src/main/acp/acp-structured-host-configured-default.test.ts
+++ b/src/main/acp/acp-structured-host-configured-default.test.ts
@@ -62,6 +62,7 @@ afterEach(async () => {
 function grokProbe() {
   return createAcpModelCatalogProbe(GROK, {
     resolveEnvironment: async () => ({ PATH: '/usr/bin' }),
+    dataDirectory: '/orca-data',
     resolveCommand: () => '/opt/grok/bin/grok',
     homePath: '/home/user',
     connect: () => {
diff --git a/src/main/acp/acp-structured-launch-preparation.ts b/src/main/acp/acp-structured-launch-preparation.ts
new file mode 100644
index 00000000000..b118c01b562
--- /dev/null
+++ b/src/main/acp/acp-structured-launch-preparation.ts
@@ -0,0 +1,32 @@
+// What a start checks on this host before it spawns the agent. A runtime Orca manages is installed
+// only when the person asks, so a start that finds no copy refuses rather than downloading one.
+
+import {
+  AgentSessionPreSpawnError,
+  type StructuredAgentSessionAcquireInput
+} from '../native-chat/agent-session-wire/structured-agent-session-adapter'
+import type { AcpStructuredLaunch } from './acp-structured-launch-resolution'
+import type { AcpStructuredSessionAdapterDeps } from './acp-structured-session-adapter-deps'
+
+/** The launch a start spawns; `closedBeforeSpawn` throws once the start was abandoned. */
+export async function prepareAcpStructuredLaunch(
+  deps: Pick<AcpStructuredSessionAdapterDeps, 'spec' | 'resolveLaunch'>,
+  acquire: Pick<StructuredAgentSessionAcquireInput, 'identity' | 'spawnToken'>,
+  closedBeforeSpawn: () => void
+): Promise<AcpStructuredLaunch> {
+  const { spec } = deps
+  const launch = await deps
+    .resolveLaunch({ identity: acquire.identity, spawnToken: acquire.spawnToken })
+    .catch((error: unknown) => {
+      throw new AgentSessionPreSpawnError(error)
+    })
+  closedBeforeSpawn()
+  // A missed lookup returns the bare name; a selected Command setting resolves or refuses.
+  if (spec.managedRuntime && launch.command === spec.command) {
+    throw new AgentSessionPreSpawnError(
+      new Error(`${spec.managedRuntime.label} is not installed on this host`),
+      { reason: 'runtimeNotInstalled' }
+    )
+  }
+  return launch
+}
diff --git a/src/main/acp/acp-structured-launch-resolution.ts b/src/main/acp/acp-structured-launch-resolution.ts
index 0052950e9e4..4330c67c81e 100644
--- a/src/main/acp/acp-structured-launch-resolution.ts
+++ b/src/main/acp/acp-structured-launch-resolution.ts
@@ -21,6 +21,11 @@ import {
   type StructuredAgentCommandSettings
 } from '../native-chat/structured-agent-command-resolution'
 import { probeAgentCliVersion } from '../agent-cli-version-probe'
+import {
+  copyBesidePinnedMembers,
+  resolveInstalledRuntimeRelease
+} from '../node-runtime/managed-runtime-release'
+import { hasExplicitTuiLaunchCommand } from '../../shared/tui-agent-launch-command-override'
 import { readAgentJournalTurn } from '../../shared/agent-session-turn-record'
 import type { JournalLoad } from '../native-chat/agent-session-journal/journal-open'
 import {
@@ -73,6 +78,8 @@ export type AcpStructuredLaunchPartDeps = {
   /** The environment the child process inherits at spawn; this process's own by default. */
   inheritedEnv?: NodeJS.ProcessEnv
   probeVersion?: typeof probeAgentCliVersion
+  /** Orca's data folder on this host, which holds the spec's managed runtime. */
+  dataDirectory: string
 } & Pick<AcpLaunchVisualsDeps, 'logger'>
 
 /** What a launch's binary and environment are read from; a catalog probe reads the same. */
@@ -87,11 +94,16 @@ export type AcpLaunchInvocationDeps = {
   refreshEnvironmentAfterMiss?: (askedAt: number) => Promise<void>
   /** Where the program starts, for a PATH entry relative to it; Orca's own when absent. */
   resolveWorkingDirectory?: () => Promise<string> | string
-} & Pick<AcpStructuredLaunchPartDeps, 'resolveCommand' | 'homePath' | 'inheritedEnv'>
+} & Pick<
+  AcpStructuredLaunchPartDeps,
+  'resolveCommand' | 'homePath' | 'inheritedEnv' | 'dataDirectory'
+>
 
 /** The binary a launch with `env` spawns: the user's Command setting when set, else the stock
- *  binary from PATH, then the agent's own install directories. A create's version check resolves
- *  through here too, so it asks about the same file. */
+ *  binary from PATH, then the agent's own install directories. A spec with a managed runtime runs
+ *  its installed release before those, and a copy from them only beside every pinned member; the
+ *  bare name when none qualifies. A create's version check resolves through here too, so it asks
+ *  about the same file. A null `dataDirectory` skips the installed release. */
 export function resolveAcpLaunchCommand(
   spec: AcpLaunchSpec,
   env: Readonly<Record<string, string>>,
@@ -99,21 +111,36 @@ export function resolveAcpLaunchCommand(
     commandSettings?: StructuredAgentCommandSettings
     resolveCommand?: typeof resolveCliCommand
     homePath?: string
-  } = {}
+    dataDirectory: string | null
+  }
 ): string {
   const homePath = env.HOME ?? env.USERPROFILE ?? options.homePath ?? homedir()
   const pathEnv = [env.PATH ?? env.Path, ...spec.installDirectories({ env, homePath })]
     .filter((entry): entry is string => Boolean(entry))
     .join(delimiter)
-  return resolveStructuredAgentCommand(
-    spec.agent,
-    options.commandSettings ?? {},
-    { pathEnv, homePath },
-    {
-      command: spec.command,
-      ...(options.resolveCommand ? { resolve: options.resolveCommand } : {})
-    }
-  )
+  const settings = options.commandSettings ?? {}
+  const resolve = (searchPath: string) =>
+    resolveStructuredAgentCommand(
+      spec.agent,
+      settings,
+      { pathEnv: searchPath, homePath },
+      {
+        command: spec.command,
+        ...(options.resolveCommand ? { resolve: options.resolveCommand } : {})
+      }
+    )
+  const { managedRuntime } = spec
+  if (!managedRuntime || hasExplicitTuiLaunchCommand(settings, spec.agent)) {
+    return resolve(pathEnv)
+  }
+  const pin = managedRuntime.pin()
+  const root = options.dataDirectory && managedRuntime.root(options.dataDirectory)
+  const release = root ? resolveInstalledRuntimeRelease(root, pin).release : null
+  if (release) {
+    return resolve(release.folder)
+  }
+  const found = resolve(pathEnv)
+  return (found !== spec.command && copyBesidePinnedMembers(found, pin)) || spec.command
 }
 
 /** Whether `command` is a release the spec runs a structured chat on (true when it names none),
@@ -202,7 +229,8 @@ export function acpStructuredLaunchPart(
         resolveWorkingDirectory: basis.launchDirectory,
         ...(deps.resolveCommand ? { resolveCommand: deps.resolveCommand } : {}),
         ...(deps.homePath ? { homePath: deps.homePath } : {}),
-        ...(deps.inheritedEnv ? { inheritedEnv: deps.inheritedEnv } : {})
+        ...(deps.inheritedEnv ? { inheritedEnv: deps.inheritedEnv } : {}),
+        dataDirectory: deps.dataDirectory
       }
     )
     const cwd = await basis.launchDirectory()
diff --git a/src/main/acp/acp-structured-managed-runtime.test.ts b/src/main/acp/acp-structured-managed-runtime.test.ts
new file mode 100644
index 00000000000..1c20b61c380
--- /dev/null
+++ b/src/main/acp/acp-structured-managed-runtime.test.ts
@@ -0,0 +1,80 @@
+import { mkdir, mkdtemp, realpath, rm, truncate, writeFile } from 'node:fs/promises'
+import { tmpdir } from 'node:os'
+import { basename, join } from 'node:path'
+import { afterEach, expect, it, vi } from 'vitest'
+import { agentSessionRecordFixture } from '../../shared/agent-session-record.test-fixture'
+import { closeProviderTimelineRigs } from '../native-chat/agent-session-timeline/provider-timeline-assembler-test-support'
+import { RUNTIME_RELEASE_RECEIPT } from '../node-runtime/managed-runtime-release'
+import { createAcpStructuredLaunchResolver } from '../runtime/structured-agent-launch-composition.test-support'
+import { GROK, openAcpAdapterRig } from './acp-structured-adapter.test-support'
+
+afterEach(() => closeProviderTimelineRigs())
+
+it('starts the installed release first, else a copy beside every pinned member', async () => {
+  const dataDirectory = await mkdtemp(join(tmpdir(), 'orca-acp-managed-'))
+  const homePath = join(dataDirectory, 'home')
+  const command = `orca-managed-${basename(dataDirectory)}`
+  const root = join(dataDirectory, 'agent-runtimes', 'grok')
+  const pin = {
+    version: '1.0',
+    url: 'https://example.test/grok-1.0.zip',
+    archiveSha256: 'a'.repeat(64),
+    archiveBytes: 10,
+    members: [
+      { path: command, sha256: 'b'.repeat(64), bytes: 6 },
+      { path: 'harness', sha256: 'c'.repeat(64), bytes: 7 }
+    ]
+  }
+  const spec = {
+    ...GROK,
+    command,
+    managedRuntime: { label: 'Grok', root: () => root, pin: () => pin }
+  }
+  const spawn = async () => {
+    const resolveLaunch = createAcpStructuredLaunchResolver(spec, {
+      store: {
+        getRecord: () => ({
+          ...agentSessionRecordFixture(),
+          provider: 'grok',
+          providerHandleChain: [],
+          accountHome: { variable: 'GROK_HOME', path: join(dataDirectory, '.grok') }
+        }),
+        pinLaunchDirectory: vi.fn()
+      },
+      readJournal: () => null,
+      resolveEnvironment: async () => ({ PATH: '', HOME: homePath }),
+      dataDirectory
+    })
+    const rig = await openAcpAdapterRig({ spec, deps: { resolveLaunch } })
+    await rig.acquire()
+    return rig.child().launch.command
+  }
+  await expect(spawn()).rejects.toMatchObject({ reason: 'runtimeNotInstalled' })
+
+  // A server without its companion beside it is no copy.
+  const localBin = join(homePath, '.local', 'bin')
+  await mkdir(localBin, { recursive: true })
+  await writeFile(join(localBin, command), '', { mode: 0o755 })
+  await expect(spawn()).rejects.toMatchObject({ reason: 'runtimeNotInstalled' })
+
+  const release = join(root, '1.0')
+  await mkdir(release, { recursive: true })
+  await writeFile(join(release, command), 'server', { mode: 0o755 })
+  await writeFile(join(release, 'harness'), 'harness', { mode: 0o755 })
+  await writeFile(
+    join(release, RUNTIME_RELEASE_RECEIPT),
+    JSON.stringify({
+      releaseId: pin.archiveSha256,
+      version: '1.0',
+      platform: process.platform,
+      arch: process.arch,
+      members: pin.members.map(({ path, bytes }) => ({ path, bytes }))
+    })
+  )
+  await writeFile(join(localBin, 'harness'), '', { mode: 0o755 })
+  expect(await spawn()).toBe(join(release, command))
+
+  await truncate(join(release, command), 2)
+  expect(await spawn()).toBe(await realpath(join(localBin, command)))
+  await rm(dataDirectory, { recursive: true, force: true })
+})
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-adapter.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-adapter.ts
index 8a3b493b766..cc563e75258 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-adapter.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-adapter.ts
@@ -135,6 +135,7 @@ export type AgentSessionPreSpawnReason = Extract<
   | 'claudeAccountFolderMissing'
   | 'claudeAccountSetupFailed'
   | 'agentCommandNotRunnable'
+  | 'runtimeNotInstalled'
 >
 
 /** Acquisition failed with first-hand proof that no provider process existed. */
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-failure-text.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-failure-text.ts
index 02d248288e1..ac7c598fecb 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-failure-text.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-failure-text.ts
@@ -36,7 +36,8 @@ const TYPED_START_REFUSALS = [
   'historyInOtherAccount',
   'claudeAccountFolderMissing',
   'claudeAccountSetupFailed',
-  'agentCommandNotRunnable'
+  'agentCommandNotRunnable',
+  'runtimeNotInstalled'
 ] as const satisfies readonly (AgentSessionFailureKind &
   AgentSessionRefusalReason<'agent_session_operation_invalid'>)[]
 
diff --git a/src/main/native-chat/structured-agent-cli-conversation-adoption.test.ts b/src/main/native-chat/structured-agent-cli-conversation-adoption.test.ts
index 42009e6d884..f39c77875d2 100644
--- a/src/main/native-chat/structured-agent-cli-conversation-adoption.test.ts
+++ b/src/main/native-chat/structured-agent-cli-conversation-adoption.test.ts
@@ -410,7 +410,8 @@ describe('adopting an OpenCode CLI conversation', () => {
     const launch = await resolveAcpLaunchInvocation(spec, unmanaged, {
       resolveEnvironment: async () => baseEnvironment,
       resolveLaunchEnv: () => launchEnv,
-      resolveCommand: () => '/test/opencode'
+      resolveCommand: () => '/test/opencode',
+      dataDirectory: root
     })
 
     expect(adoption.transcriptPath).toBe(configuredDb)
diff --git a/src/main/node-runtime/managed-runtime-release.ts b/src/main/node-runtime/managed-runtime-release.ts
new file mode 100644
index 00000000000..f16ade04e42
--- /dev/null
+++ b/src/main/node-runtime/managed-runtime-release.ts
@@ -0,0 +1,149 @@
+// The installed releases of a runtime Orca downloads for an agent: `<root>/<version>/` holding the
+// pinned members and a receipt written before the folder was renamed into place. Read-only, and
+// cheap enough for every launch: a full hash is only ever taken by an install.
+
+import { lstatSync, readFileSync, readdirSync, realpathSync, statSync } from 'node:fs'
+import { basename, dirname, join } from 'node:path'
+import { z } from 'zod'
+import { isDefinitiveAbsence } from '../../shared/definitive-filesystem-absence'
+
+export type ManagedRuntimePin = {
+  version: string
+  url: string
+  archiveSha256: string
+  /** The decoded archive's size. */
+  archiveBytes: number
+  /** Archive-relative path, sha256 and size of every executable the release must hold. */
+  members: readonly { path: string; sha256: string; bytes: number }[]
+}
+
+/** A runtime Orca installs only when the person asks; a launch reads what is installed. */
+export type ManagedRuntime = {
+  /** Shown to the person, e.g. "Antigravity". */
+  label: string
+  /** The folder that holds only this runtime's releases. */
+  root(dataDirectory: string): string
+  /** This host's pinned release; null where none is published. */
+  pin(): ManagedRuntimePin | null
+}
+
+export const RUNTIME_RELEASE_RECEIPT = '.install-complete.json'
+const RECEIPT_MAX_BYTES = 8 * 1024
+const VERSION_ORDER = new Intl.Collator(undefined, { numeric: true })
+
+const runtimeReleaseReceiptSchema = z.object({
+  releaseId: z.string().regex(/^[a-f0-9]{64}$/),
+  version: z.string().min(1),
+  platform: z.string(),
+  arch: z.string(),
+  members: z.array(z.object({ path: z.string().min(1), bytes: z.number().int().positive() })).min(1)
+})
+
+export type InstalledRuntimeRelease = {
+  folder: string
+  version: string
+  /** The pinned release itself, rather than an older one kept runnable. */
+  current: boolean
+}
+
+/** What a release folder read proved: whole, definitively not (absent, mismatched or partial), or
+ *  unknown because the read itself failed. */
+type ReleaseRead = { releaseId: string } | 'broken' | 'unreadable'
+
+export type InstalledRuntimeReleases = {
+  /** The release a launch runs: the pinned one when installed whole, else the newest other whole
+   *  one; null when none is. Staging, links and anything incomplete never count. */
+  release: InstalledRuntimeRelease | null
+  /** Release folders that are definitively not whole, e.g. a member deleted or truncated. */
+  broken: string[]
+  /** Some folder could not be read, so whether it is whole is unknown. */
+  unreadable: boolean
+}
+
+export function resolveInstalledRuntimeRelease(
+  root: string,
+  pin: ManagedRuntimePin | null
+): InstalledRuntimeReleases {
+  let names: string[]
+  try {
+    names = readdirSync(root)
+  } catch (error) {
+    return { release: null, broken: [], unreadable: !isDefinitiveAbsence(error) }
+  }
+  const reads = names
+    .filter((name) => !name.startsWith('.'))
+    .map((name) => ({ name, read: readRelease(join(root, name), name) }))
+  const releases = reads.flatMap(({ name, read }) =>
+    typeof read === 'object' ? [{ name, releaseId: read.releaseId }] : []
+  )
+  const pinned = releases.find(
+    (release) => release.name === pin?.version && release.releaseId === pin.archiveSha256
+  )
+  const chosen = pinned ?? releases.sort((a, b) => VERSION_ORDER.compare(b.name, a.name))[0]
+  return {
+    release: chosen
+      ? { folder: join(root, chosen.name), version: chosen.name, current: chosen === pinned }
+      : null,
+    broken: reads.filter(({ read }) => read === 'broken').map(({ name }) => name),
+    unreadable: reads.some(({ read }) => read === 'unreadable')
+  }
+}
+
+/** `command`'s real path when every pinned member sits beside it, as the server expects its
+ *  companions; null otherwise, so a lone server file found elsewhere is never started. */
+export function copyBesidePinnedMembers(
+  command: string,
+  pin: ManagedRuntimePin | null
+): string | null {
+  try {
+    const real = realpathSync(command)
+    const whole = (pin?.members ?? []).every((member) => {
+      const file = statSync(join(dirname(real), basename(member.path)))
+      return file.isFile() && (process.platform === 'win32' || (file.mode & 0o111) !== 0)
+    })
+    return whole ? real : null
+  } catch {
+    return null
+  }
+}
+
+function readRelease(folder: string, version: string): ReleaseRead {
+  try {
+    const receiptPath = join(folder, RUNTIME_RELEASE_RECEIPT)
+    const stat = lstatSync(receiptPath)
+    if (!lstatSync(folder).isDirectory() || !stat.isFile() || stat.size > RECEIPT_MAX_BYTES) {
+      return 'broken'
+    }
+    const receipt = runtimeReleaseReceiptSchema.safeParse(
+      parseJson(readFileSync(receiptPath, 'utf8'))
+    )
+    const whole =
+      receipt.success &&
+      receipt.data.version === version &&
+      receipt.data.platform === process.platform &&
+      receipt.data.arch === process.arch &&
+      receipt.data.members.every((member) => {
+        const segments = member.path.split('/')
+        if (segments.some((segment) => !segment || segment === '.' || segment === '..')) {
+          return false
+        }
+        const file = lstatSync(join(folder, ...segments))
+        return (
+          file.isFile() &&
+          file.size === member.bytes &&
+          (process.platform === 'win32' || (file.mode & 0o111) !== 0)
+        )
+      })
+    return whole ? { releaseId: receipt.data.releaseId } : 'broken'
+  } catch (error) {
+    return isDefinitiveAbsence(error) ? 'broken' : 'unreadable'
+  }
+}
+
+function parseJson(text: string): unknown {
+  try {
+    return JSON.parse(text)
+  } catch {
+    return null
+  }
+}
diff --git a/src/main/runtime/structured-agent-launch-composition.test-support.ts b/src/main/runtime/structured-agent-launch-composition.test-support.ts
index 2c3d55753d5..2dfee770cbc 100644
--- a/src/main/runtime/structured-agent-launch-composition.test-support.ts
+++ b/src/main/runtime/structured-agent-launch-composition.test-support.ts
@@ -110,12 +110,14 @@ export function createCodexStructuredLaunchResolver(
 /** Unsealed unless a token is passed: the env an agent part produced, before the seal. */
 export function createAcpStructuredLaunchResolver(
   spec: AcpLaunchSpec,
-  deps: LaunchTestSources & AcpStructuredLaunchPartDeps
+  deps: LaunchTestSources &
+    Omit<AcpStructuredLaunchPartDeps, 'dataDirectory'> &
+    Partial<Pick<AcpStructuredLaunchPartDeps, 'dataDirectory'>>
 ) {
   return withTestSpawnToken(
     acpStructuredAgentDefinition(spec),
     launchSources(deps),
-    acpStructuredLaunchPart(spec, deps),
+    acpStructuredLaunchPart(spec, { dataDirectory: '/orca-data', ...deps }),
     null
   )
 }
diff --git a/src/main/runtime/structured-agent-model-catalog-discovery.ts b/src/main/runtime/structured-agent-model-catalog-discovery.ts
index 2ebc814cfe3..632339b57f8 100644
--- a/src/main/runtime/structured-agent-model-catalog-discovery.ts
+++ b/src/main/runtime/structured-agent-model-catalog-discovery.ts
@@ -70,6 +70,7 @@ export function acpModelCatalogDiscovery(
     probe: createAcpModelCatalogProbe(spec, {
       resolveEnvironment: environment.resolveBaseEnvironment,
       refreshEnvironmentAfterMiss: environment.refreshAfterMissingProgram,
+      dataDirectory: deps.stateDirectory,
       ...(deps.resolveAgentLaunchEnv ? { resolveLaunchEnv: deps.resolveAgentLaunchEnv } : {}),
       ...(deps.resolveAgentCommandSettings
         ? { resolveCommandSettings: deps.resolveAgentCommandSettings }
diff --git a/src/main/runtime/structured-agent-runtime-metadata.ts b/src/main/runtime/structured-agent-runtime-metadata.ts
index c3ef273c8f9..e622c3d571d 100644
--- a/src/main/runtime/structured-agent-runtime-metadata.ts
+++ b/src/main/runtime/structured-agent-runtime-metadata.ts
@@ -42,7 +42,11 @@ function acpMetadata(spec: AcpLaunchSpec): StructuredAgentRuntimeMetadata {
           launchCheck: {
             resolveLaunch: (shellEnv, commandSettings) => {
               const env = { ...shellEnv, ...spec.env }
-              return { command: resolveAcpLaunchCommand(spec, env, { commandSettings }), env }
+              const command = resolveAcpLaunchCommand(spec, env, {
+                commandSettings,
+                dataDirectory: null
+              })
+              return { command, env }
             },
             supportsVersion: (launch) => acpLaunchVersionSupported(spec, launch)
           }
diff --git a/src/main/runtime/structured-agent-runtime-registrations.ts b/src/main/runtime/structured-agent-runtime-registrations.ts
index c7c6cb2da69..3532428938c 100644
--- a/src/main/runtime/structured-agent-runtime-registrations.ts
+++ b/src/main/runtime/structured-agent-runtime-registrations.ts
@@ -117,6 +117,7 @@ function createAcpAdapter(
     const part = acpStructuredLaunchPart(spec, {
       readJournal,
       ...(deps.resolveAgentFullAccess ? { resolveFullAccess: deps.resolveAgentFullAccess } : {}),
+      dataDirectory: deps.stateDirectory,
       logger: deps.logger
     })
     return new AcpStructuredSessionAdapter({
diff --git a/src/renderer/src/components/native-chat/agent-session-failure-words-text.ts b/src/renderer/src/components/native-chat/agent-session-failure-words-text.ts
index 0cb3ffb6db1..155a683fb04 100644
--- a/src/renderer/src/components/native-chat/agent-session-failure-words-text.ts
+++ b/src/renderer/src/components/native-chat/agent-session-failure-words-text.ts
@@ -135,6 +135,12 @@ const PIECES: Record<AgentSessionFailureCopyId, (values: AgentSessionFailureCopy
         COPY.agentCommandNotRunnable,
         values
       ),
+    runtimeNotInstalled: (values) =>
+      translate(
+        'components.native-chat.failureWords.runtimeNotInstalled',
+        COPY.runtimeNotInstalled,
+        values
+      ),
     chooseClaudeAccount: () =>
       translate(
         'components.native-chat.failureWords.chooseClaudeAccount',
diff --git a/src/renderer/src/i18n/en-runtime-required.json b/src/renderer/src/i18n/en-runtime-required.json
index f991f446662..8a9ed342cdd 100644
--- a/src/renderer/src/i18n/en-runtime-required.json
+++ b/src/renderer/src/i18n/en-runtime-required.json
@@ -2849,6 +2849,7 @@
       "failureWords": {
         "accountSwitchInProgress": "A Claude account switch is in progress. Try again after it finishes.",
         "agentCommandNotRunnable": "{{agent}}'s Command in Settings → Agents must be a program path or name Orca can find, with no arguments or variables. Change it or reset it.",
+        "runtimeNotInstalled": "{{agent}} isn't installed on the computer running this chat. Install it from the chat in a current version of Orca.",
         "agentCommandNotSignedIn": "Sign in to {{agent}} with `{{loginCommand}}` on the computer running this chat.",
         "agentNotSignedIn": "Sign in to {{agent}}.",
         "answerUnconfirmed": "Your answer was recorded but the agent did not confirm it.",
diff --git a/src/renderer/src/i18n/locales/en.json b/src/renderer/src/i18n/locales/en.json
index 44483b889ca..ba25a37a7d7 100644
--- a/src/renderer/src/i18n/locales/en.json
+++ b/src/renderer/src/i18n/locales/en.json
@@ -18194,6 +18194,7 @@
         "claudeAccountFolderMissing": "The selected Claude account's folder is missing. Sign in to it again or choose another account.",
         "claudeAccountSetupFailed": "The selected Claude account could not be set up. Try again or choose another account.",
         "agentCommandNotRunnable": "{{agent}}'s Command in Settings → Agents must be a program path or name Orca can find, with no arguments or variables. Change it or reset it.",
+        "runtimeNotInstalled": "{{agent}} isn't installed on the computer running this chat. Install it from the chat in a current version of Orca.",
         "chooseClaudeAccount": "Choose or add one in Claude Accounts settings.",
         "chooseClaudeAccountThenRunCommand": "Choose or add one in Claude Accounts settings, then run /{{command}} again.",
         "chooseClaudeAccountThenSend": "Choose or add one in Claude Accounts settings, then send your message again.",
diff --git a/src/renderer/src/i18n/locales/es.json b/src/renderer/src/i18n/locales/es.json
index 0b3523186cb..ba4de069f0d 100644
--- a/src/renderer/src/i18n/locales/es.json
+++ b/src/renderer/src/i18n/locales/es.json
@@ -17974,6 +17974,7 @@
         "claudeAccountFolderMissing": "Falta la carpeta de la cuenta de Claude seleccionada. Vuelva a iniciar sesión en ella o elija otra cuenta.",
         "claudeAccountSetupFailed": "No se pudo configurar la cuenta de Claude seleccionada. Vuelva a intentarlo o elija otra cuenta.",
         "agentCommandNotRunnable": "{{agent}}: el Comando en Ajustes → Agentes debe ser la ruta o el nombre de un programa que Orca pueda encontrar, sin argumentos ni variables. Cámbielo o restablézcalo con Reiniciar.",
+        "runtimeNotInstalled": "{{agent}} no está instalado en el equipo que ejecuta este chat. Instálelo desde el chat en una versión actual de Orca.",
         "chooseClaudeAccount": "Elija o agregue una en la configuración de Cuentas de Claude.",
         "chooseClaudeAccountThenRunCommand": "Elija o agregue una en la configuración de Cuentas de Claude y vuelva a ejecutar /{{command}}.",
         "chooseClaudeAccountThenSend": "Elija o agregue una en la configuración de Cuentas de Claude y vuelva a enviar su mensaje.",
diff --git a/src/renderer/src/i18n/locales/fr.json b/src/renderer/src/i18n/locales/fr.json
index f663d5a95fc..625e9e880e2 100644
--- a/src/renderer/src/i18n/locales/fr.json
+++ b/src/renderer/src/i18n/locales/fr.json
@@ -18078,6 +18078,7 @@
         "claudeAccountFolderMissing": "Le dossier du compte Claude sélectionné est introuvable. Reconnectez-vous à ce compte ou choisissez-en un autre.",
         "claudeAccountSetupFailed": "Le compte Claude sélectionné n'a pas pu être configuré. Réessayez ou choisissez un autre compte.",
         "agentCommandNotRunnable": "{{agent}} : la Commande dans Paramètres → Agents doit être le chemin ou le nom d'un programme qu'Orca peut trouver, sans arguments ni variables. Modifiez-la ou réinitialisez-la.",
+        "runtimeNotInstalled": "{{agent}} n'est pas installé sur l'ordinateur qui exécute ce chat. Installez-le depuis le chat dans une version récente d'Orca.",
         "chooseClaudeAccount": "Choisissez-en un ou ajoutez-en un dans les paramètres Comptes Claude.",
         "chooseClaudeAccountThenRunCommand": "Choisissez-en un ou ajoutez-en un dans les paramètres Comptes Claude, puis relancez /{{command}}.",
         "chooseClaudeAccountThenSend": "Choisissez-en un ou ajoutez-en un dans les paramètres Comptes Claude, puis renvoyez votre message.",
diff --git a/src/renderer/src/i18n/locales/ja.json b/src/renderer/src/i18n/locales/ja.json
index b14f79ffc6d..9c5e18a06fc 100644
--- a/src/renderer/src/i18n/locales/ja.json
+++ b/src/renderer/src/i18n/locales/ja.json
@@ -18009,6 +18009,7 @@
         "claudeAccountFolderMissing": "選択した Claude アカウントのフォルダーが見つかりません。もう一度サインインするか、別のアカウントを選択してください。",
         "claudeAccountSetupFailed": "選択した Claude アカウントを設定できませんでした。もう一度試すか、別のアカウントを選択してください。",
         "agentCommandNotRunnable": "[設定] → [Agent] にある {{agent}} の [コマンド] には、Orca が見つけられるプログラムのパスまたは名前を、引数や変数なしで指定する必要があります。変更するか、[リセット] してください。",
+        "runtimeNotInstalled": "{{agent}} はこのチャットを実行しているコンピューターにインストールされていません。最新バージョンの Orca でチャットからインストールしてください。",
         "chooseClaudeAccount": "Claude アカウントの設定で選択または追加してください。",
         "chooseClaudeAccountThenRunCommand": "Claude アカウントの設定で選択または追加してから、/{{command}} をもう一度実行してください。",
         "chooseClaudeAccountThenSend": "Claude アカウントの設定で選択または追加してから、メッセージをもう一度送信してください。",
diff --git a/src/renderer/src/i18n/locales/ko.json b/src/renderer/src/i18n/locales/ko.json
index a36344a4dd5..1575022d30b 100644
--- a/src/renderer/src/i18n/locales/ko.json
+++ b/src/renderer/src/i18n/locales/ko.json
@@ -18009,6 +18009,7 @@
         "claudeAccountFolderMissing": "선택한 Claude 계정의 폴더가 없습니다. 다시 로그인하거나 다른 계정을 선택하세요.",
         "claudeAccountSetupFailed": "선택한 Claude 계정을 설정할 수 없습니다. 다시 시도하거나 다른 계정을 선택하세요.",
         "agentCommandNotRunnable": "{{agent}}의 설정 → 에이전트 → 명령은 Orca가 찾을 수 있는 프로그램 경로나 이름이어야 하며, 인수나 변수를 포함할 수 없습니다. 변경하거나 재설정하세요.",
+        "runtimeNotInstalled": "{{agent}}이(가) 이 채팅을 실행하는 컴퓨터에 설치되어 있지 않습니다. 최신 버전의 Orca에서 채팅을 통해 설치하세요.",
         "chooseClaudeAccount": "Claude 계정 설정에서 선택하거나 추가하세요.",
         "chooseClaudeAccountThenRunCommand": "Claude 계정 설정에서 선택하거나 추가한 다음 /{{command}}을(를) 다시 실행하세요.",
         "chooseClaudeAccountThenSend": "Claude 계정 설정에서 선택하거나 추가한 다음 메시지를 다시 보내세요.",
diff --git a/src/renderer/src/i18n/locales/zh.json b/src/renderer/src/i18n/locales/zh.json
index 2e928e8e7e9..d84bb132534 100644
--- a/src/renderer/src/i18n/locales/zh.json
+++ b/src/renderer/src/i18n/locales/zh.json
@@ -17974,6 +17974,7 @@
         "claudeAccountFolderMissing": "所选 Claude 账户的文件夹不存在。请重新登录该账户或选择其他账户。",
         "claudeAccountSetupFailed": "无法设置所选 Claude 账户。请重试或选择其他账户。",
         "agentCommandNotRunnable": "{{agent}} 在设置 → 智能体中的命令必须是 Orca 能找到的程序路径或名称，且不能包含参数或变量。请修改或重置。",
+        "runtimeNotInstalled": "运行此聊天的计算机上未安装 {{agent}}。请在最新版本的 Orca 中从聊天里安装。",
         "chooseClaudeAccount": "请在 Claude 账户设置中选择或添加一个。",
         "chooseClaudeAccountThenRunCommand": "请在 Claude 账户设置中选择或添加一个，然后重新运行 /{{command}}。",
         "chooseClaudeAccountThenSend": "请在 Claude 账户设置中选择或添加一个，然后重新发送您的消息。",
diff --git a/src/shared/agent-session-failure-copy.ts b/src/shared/agent-session-failure-copy.ts
index c6f430a00c9..007bbb0b056 100644
--- a/src/shared/agent-session-failure-copy.ts
+++ b/src/shared/agent-session-failure-copy.ts
@@ -71,6 +71,8 @@ export const AGENT_SESSION_FAILURE_COPY = {
   claudeAccountSetupFailed: CLAUDE_PROFILE_SETUP_FAILED_MESSAGE,
   agentCommandNotRunnable:
     "{{agent}}'s Command in Settings → Agents must be a program path or name Orca can find, with no arguments or variables. Change it or reset it.",
+  runtimeNotInstalled:
+    "{{agent}} isn't installed on the computer running this chat. Install it from the chat in a current version of Orca.",
   chooseClaudeAccount: 'Choose or add one in Claude Accounts settings.',
   chooseClaudeAccountThenRunCommand:
     'Choose or add one in Claude Accounts settings, then run /{{command}} again.',
diff --git a/src/shared/agent-session-failure-words.ts b/src/shared/agent-session-failure-words.ts
index 9a2572a9cd2..73e2762d1cf 100644
--- a/src/shared/agent-session-failure-words.ts
+++ b/src/shared/agent-session-failure-words.ts
@@ -208,6 +208,8 @@ const FAILURE_SENTENCES = {
   claudeAccountSetupFailed: (_context, _fact, _surface, say) => say('claudeAccountSetupFailed'),
   agentCommandNotRunnable: (context, _fact, _surface, say) =>
     say('agentCommandNotRunnable', agent(say, context)),
+  runtimeNotInstalled: (context, _fact, _surface, say) =>
+    say('runtimeNotInstalled', agent(say, context)),
   managedAccountUnsupported: (context, _fact, _surface, say) =>
     joinSentences([
       say('managedAccountUnsupported'),
diff --git a/src/shared/agent-session-failure.ts b/src/shared/agent-session-failure.ts
index 5ae24ee4588..c31e47894b9 100644
--- a/src/shared/agent-session-failure.ts
+++ b/src/shared/agent-session-failure.ts
@@ -37,6 +37,7 @@ export const AGENT_SESSION_FAILURE_KINDS = [
   'claudeAccountFolderMissing',
   'claudeAccountSetupFailed',
   'agentCommandNotRunnable',
+  'runtimeNotInstalled',
   'providerExited',
   'restartFailed',
   'providerRejected',
diff --git a/src/shared/agent-session-refusal-details.ts b/src/shared/agent-session-refusal-details.ts
index 8aea50584bf..6214543aa73 100644
--- a/src/shared/agent-session-refusal-details.ts
+++ b/src/shared/agent-session-refusal-details.ts
@@ -84,6 +84,8 @@ export const AGENT_SESSION_REFUSAL_REASONS = {
     'claudeAccountSetupFailed',
     /** Settings → Agents → Command names no program this host can run. */
     'agentCommandNotRunnable',
+    /** The runtime Orca installs for the agent is not installed on this host. */
+    'runtimeNotInstalled',
     /** The agent started, then Orca could not open the chat's conversation for it. */
     'attachFailed'
   ],
diff --git a/src/shared/agent-session-refusal-reason-words.ts b/src/shared/agent-session-refusal-reason-words.ts
index 4c9da698eb5..781f36bd82f 100644
--- a/src/shared/agent-session-refusal-reason-words.ts
+++ b/src/shared/agent-session-refusal-reason-words.ts
@@ -118,6 +118,7 @@ const REASON_WORDS = {
     claudeAccountFolderMissing: { fact: 'claudeAccountFolderMissing', action: 'actFirst' },
     claudeAccountSetupFailed: { fact: 'claudeAccountSetupFailed', action: 'retry' },
     agentCommandNotRunnable: { fact: 'agentCommandNotRunnable', action: 'actFirst' },
+    runtimeNotInstalled: { fact: 'runtimeNotInstalled', action: 'actFirst' },
     attachFailed: codeWords('retry')
   },
   agent_session_ownership_unknown: {
diff --git a/src/shared/structured-agent-session-dispatch-rejection.ts b/src/shared/structured-agent-session-dispatch-rejection.ts
index 800c0e8b439..0007e00f30a 100644
--- a/src/shared/structured-agent-session-dispatch-rejection.ts
+++ b/src/shared/structured-agent-session-dispatch-rejection.ts
@@ -96,6 +96,7 @@ const KIND_CATEGORY = {
   claudeAccountFolderMissing: 'startFailed',
   claudeAccountSetupFailed: 'startFailed',
   agentCommandNotRunnable: 'startFailed',
+  runtimeNotInstalled: 'startFailed',
   restartFailed: 'startFailed',
   providerRejected: 'content',
   attachmentInvalid: 'content',
@@ -127,6 +128,7 @@ const KIND_VERDICT = {
   claudeAccountFolderMissing: 'failure',
   claudeAccountSetupFailed: 'failure',
   agentCommandNotRunnable: 'failure',
+  runtimeNotInstalled: 'failure',
   restartFailed: 'failure',
   providerRejected: 'failure',
   attachmentInvalid: 'failure',