diff --git a/src/renderer/src/components/onboarding/OnboardingInlineCommandTerminal.tsx b/src/renderer/src/components/onboarding/OnboardingInlineCommandTerminal.tsx
index cf1cf53aa..9f7c8da13 100644
--- a/src/renderer/src/components/onboarding/OnboardingInlineCommandTerminal.tsx
+++ b/src/renderer/src/components/onboarding/OnboardingInlineCommandTerminal.tsx
@@ -5,6 +5,7 @@ import { PASTE_TERMINAL_TEXT_EVENT, type PasteTerminalTextDetail } from '@/const
 import { focusTerminalTabSurface } from '@/lib/focus-terminal-tab-surface'
 import { useAppStore } from '@/store'
 import { translate } from '@/i18n/i18n'
+import { brandEphemeralSetupTerminalWorktreeId } from '../../../../shared/ephemeral-setup-terminal-worktree-id'
 
 const ONBOARDING_INLINE_TERMINAL_WORKTREE_ID = 'onboarding-inline-terminal'
 const AUTO_INSERT_DELAY_MS = 250
@@ -30,6 +31,10 @@ type OnboardingInlineCommandTerminalProps = {
   onTerminalExit?: () => void
 }
 
+/**
+ * Inline pane that runs a one-off setup command (skill install, feature tip) in an
+ * ephemeral floating-scoped terminal, auto-inserting the command once the PTY is ready.
+ */
 export function OnboardingInlineCommandTerminal({
   command,
   title,
@@ -39,12 +44,18 @@ export function OnboardingInlineCommandTerminal({
   terminalTopMarginPx = 20,
   descriptionPaddingClassName = 'px-4 py-3',
   autoScrollIntoView = true,
-  worktreeId = ONBOARDING_INLINE_TERMINAL_WORKTREE_ID,
+  worktreeId: worktreeIdProp = ONBOARDING_INLINE_TERMINAL_WORKTREE_ID,
   shellOverride,
   onOpened,
   onInteracted,
   onTerminalExit
 }: OnboardingInlineCommandTerminalProps): React.JSX.Element {
+  // Why: brand the id so a remote runtime scopes this ephemeral terminal to the
+  // floating terminal instead of rejecting the synthetic id.
+  const worktreeId = useMemo(
+    () => brandEphemeralSetupTerminalWorktreeId(worktreeIdProp),
+    [worktreeIdProp]
+  )
   const createTab = useAppStore((s) => s.createTab)
   const closeTab = useAppStore((s) => s.closeTab)
   const setActiveTabForWorktree = useAppStore((s) => s.setActiveTabForWorktree)
diff --git a/src/renderer/src/components/terminal-pane/remote-runtime-pty-transport.test.ts b/src/renderer/src/components/terminal-pane/remote-runtime-pty-transport.test.ts
index fd8cc3bc7..d11d07afe 100644
--- a/src/renderer/src/components/terminal-pane/remote-runtime-pty-transport.test.ts
+++ b/src/renderer/src/components/terminal-pane/remote-runtime-pty-transport.test.ts
@@ -550,6 +550,30 @@ describe('createRemoteRuntimePtyTransport', () => {
     )
   })
 
+  it('scopes ephemeral setup terminals to the floating-terminal selector (#6789)', async () => {
+    const { brandEphemeralSetupTerminalWorktreeId } = await import(
+      '../../../../shared/ephemeral-setup-terminal-worktree-id'
+    )
+    const { createRemoteRuntimePtyTransport } = await import('./remote-runtime-pty-transport')
+    const transport = createRemoteRuntimePtyTransport('env-1', {
+      worktreeId: brandEphemeralSetupTerminalWorktreeId('feature-wall-orchestration-skill-terminal'),
+      tabId: 'tab-1',
+      leafId: 'pane:1'
+    })
+
+    await transport.connect({ url: '', callbacks: {} })
+
+    expect(runtimeCall).toHaveBeenCalledWith(
+      expect.objectContaining({
+        selector: 'env-1',
+        method: 'terminal.create',
+        params: expect.objectContaining({
+          worktree: 'id:global-floating-terminal'
+        })
+      })
+    )
+  })
+
   it('passes startup command delivery when creating the remote runtime terminal', async () => {
     const { createRemoteRuntimePtyTransport } = await import('./remote-runtime-pty-transport')
     const transport = createRemoteRuntimePtyTransport('env-1', {
diff --git a/src/renderer/src/components/terminal-pane/remote-runtime-pty-transport.ts b/src/renderer/src/components/terminal-pane/remote-runtime-pty-transport.ts
index 71cffb568..44f7745b7 100644
--- a/src/renderer/src/components/terminal-pane/remote-runtime-pty-transport.ts
+++ b/src/renderer/src/components/terminal-pane/remote-runtime-pty-transport.ts
@@ -22,7 +22,10 @@ import {
   getRemoteRuntimeTerminalMultiplexer,
   type RemoteRuntimeMultiplexedTerminal
 } from '../../runtime/remote-runtime-terminal-multiplexer'
-import { toRuntimeWorktreeSelector } from '../../runtime/runtime-worktree-selector'
+import {
+  toRuntimeTerminalWorktreeSelector,
+  toRuntimeWorktreeSelector
+} from '../../runtime/runtime-worktree-selector'
 import {
   createRemoteRuntimePtyTextBatcher,
   createRemoteRuntimeViewportBatcher
@@ -45,6 +48,11 @@ function isRemoteTerminalGoneMessage(message: string): boolean {
   )
 }
 
+/**
+ * PTY transport backing a renderer terminal pane with a terminal on a remote Orca
+ * runtime, over runtime RPC plus the multiplexed stream (create, subscribe, input,
+ * resize, close, reattach).
+ */
 export function createRemoteRuntimePtyTransport(
   runtimeEnvironmentId: string,
   opts: IpcPtyTransportOptions = {}
@@ -467,7 +475,7 @@ export function createRemoteRuntimePtyTransport(
         const launchTokenToSend = options.launchToken ?? launchToken
         const launchAgentToSend = options.launchAgent ?? launchAgent
         const created = await callRuntime<{ terminal: RuntimeTerminalCreate }>('terminal.create', {
-          worktree: toRuntimeWorktreeSelector(worktreeId),
+          worktree: toRuntimeTerminalWorktreeSelector(worktreeId),
           ...(commandToSend !== undefined ? { command: commandToSend } : {}),
           ...(startupCommandDeliveryToSend !== undefined
             ? { startupCommandDelivery: startupCommandDeliveryToSend }
diff --git a/src/renderer/src/runtime/runtime-worktree-selector.test.ts b/src/renderer/src/runtime/runtime-worktree-selector.test.ts
index 42817b820..0aee6d057 100644
--- a/src/renderer/src/runtime/runtime-worktree-selector.test.ts
+++ b/src/renderer/src/runtime/runtime-worktree-selector.test.ts
@@ -1,5 +1,9 @@
 import { describe, expect, it } from 'vitest'
-import { toRuntimeWorktreeSelector } from './runtime-worktree-selector'
+import {
+  toRuntimeTerminalWorktreeSelector,
+  toRuntimeWorktreeSelector
+} from './runtime-worktree-selector'
+import { brandEphemeralSetupTerminalWorktreeId } from '../../../shared/ephemeral-setup-terminal-worktree-id'
 
 describe('toRuntimeWorktreeSelector', () => {
   it('addresses raw worktree IDs as runtime ID selectors', () => {
@@ -14,3 +18,18 @@ describe('toRuntimeWorktreeSelector', () => {
     expect(toRuntimeWorktreeSelector('')).toBe('')
   })
 })
+
+describe('toRuntimeTerminalWorktreeSelector', () => {
+  it('resolves ephemeral setup terminals to the floating-terminal scope', () => {
+    expect(
+      toRuntimeTerminalWorktreeSelector(
+        brandEphemeralSetupTerminalWorktreeId('feature-wall-orchestration-skill-terminal')
+      )
+    ).toBe('id:global-floating-terminal')
+  })
+
+  it('addresses real worktree ids like the base selector', () => {
+    expect(toRuntimeTerminalWorktreeSelector('wt-1')).toBe('id:wt-1')
+    expect(toRuntimeTerminalWorktreeSelector('id:wt-1')).toBe('id:wt-1')
+  })
+})
diff --git a/src/renderer/src/runtime/runtime-worktree-selector.ts b/src/renderer/src/runtime/runtime-worktree-selector.ts
index 2467e0dfa..0a33843ee 100644
--- a/src/renderer/src/runtime/runtime-worktree-selector.ts
+++ b/src/renderer/src/runtime/runtime-worktree-selector.ts
@@ -1,5 +1,9 @@
+import { FLOATING_TERMINAL_WORKTREE_ID } from '../../../shared/constants'
+import { isEphemeralSetupTerminalWorktreeId } from '../../../shared/ephemeral-setup-terminal-worktree-id'
+
 const RUNTIME_WORKTREE_ID_SELECTOR_PREFIX = 'id:'
 
+/** Address a raw worktree id as a runtime `id:` selector; passes through empty or already-prefixed values. */
 export function toRuntimeWorktreeSelector(worktreeId: string): string {
   const trimmed = worktreeId.trim()
   if (!trimmed || trimmed.startsWith(RUNTIME_WORKTREE_ID_SELECTOR_PREFIX)) {
@@ -7,3 +11,15 @@ export function toRuntimeWorktreeSelector(worktreeId: string): string {
   }
   return `${RUNTIME_WORKTREE_ID_SELECTOR_PREFIX}${trimmed}`
 }
+
+/**
+ * Runtime selector for a terminal's worktree id. Ephemeral setup terminals have no
+ * worktree on the runtime, so resolve them to the floating-terminal scope (home dir)
+ * every runtime understands; other ids map to their own `id:` selector.
+ */
+export function toRuntimeTerminalWorktreeSelector(worktreeId: string): string {
+  if (isEphemeralSetupTerminalWorktreeId(worktreeId.trim())) {
+    return toRuntimeWorktreeSelector(FLOATING_TERMINAL_WORKTREE_ID)
+  }
+  return toRuntimeWorktreeSelector(worktreeId)
+}
diff --git a/src/shared/ephemeral-setup-terminal-worktree-id.test.ts b/src/shared/ephemeral-setup-terminal-worktree-id.test.ts
new file mode 100644
index 000000000..c93c869ac
--- /dev/null
+++ b/src/shared/ephemeral-setup-terminal-worktree-id.test.ts
@@ -0,0 +1,33 @@
+import { describe, expect, it } from 'vitest'
+import {
+  EPHEMERAL_SETUP_TERMINAL_WORKTREE_ID_PREFIX,
+  brandEphemeralSetupTerminalWorktreeId,
+  isEphemeralSetupTerminalWorktreeId
+} from './ephemeral-setup-terminal-worktree-id'
+
+describe('ephemeral setup terminal worktree id', () => {
+  it('brands a panel id with the ephemeral prefix', () => {
+    expect(brandEphemeralSetupTerminalWorktreeId('feature-wall-orchestration-skill-terminal')).toBe(
+      `${EPHEMERAL_SETUP_TERMINAL_WORKTREE_ID_PREFIX}feature-wall-orchestration-skill-terminal`
+    )
+  })
+
+  it('is idempotent for already-branded ids', () => {
+    const branded = brandEphemeralSetupTerminalWorktreeId('settings-orchestration-skill-terminal')
+    expect(brandEphemeralSetupTerminalWorktreeId(branded)).toBe(branded)
+  })
+
+  it('recognizes branded ids and rejects real worktree ids', () => {
+    expect(
+      isEphemeralSetupTerminalWorktreeId(
+        brandEphemeralSetupTerminalWorktreeId('feature-tip-cli-skills-terminal')
+      )
+    ).toBe(true)
+    expect(isEphemeralSetupTerminalWorktreeId('repo-1::/work/orca/wt')).toBe(false)
+    expect(isEphemeralSetupTerminalWorktreeId('global-floating-terminal')).toBe(false)
+  })
+
+  it('does not introduce the `::` worktree id separator', () => {
+    expect(brandEphemeralSetupTerminalWorktreeId('onboarding-inline-terminal')).not.toContain('::')
+  })
+})
diff --git a/src/shared/ephemeral-setup-terminal-worktree-id.ts b/src/shared/ephemeral-setup-terminal-worktree-id.ts
new file mode 100644
index 000000000..005659b7c
--- /dev/null
+++ b/src/shared/ephemeral-setup-terminal-worktree-id.ts
@@ -0,0 +1,19 @@
+// Inline setup/onboarding terminals have no backing worktree. Branding their
+// per-panel id lets the terminal RPC layer scope them to the floating terminal,
+// instead of leaking an unresolvable selector to a remote runtime (#6789).
+export const EPHEMERAL_SETUP_TERMINAL_WORKTREE_ID_PREFIX = 'ephemeral-setup-terminal:'
+
+/**
+ * Brand a per-panel setup-terminal id so the terminal RPC layer routes it to the
+ * floating-terminal scope on a runtime. Idempotent for already-branded ids.
+ */
+export function brandEphemeralSetupTerminalWorktreeId(panelId: string): string {
+  return isEphemeralSetupTerminalWorktreeId(panelId)
+    ? panelId
+    : `${EPHEMERAL_SETUP_TERMINAL_WORKTREE_ID_PREFIX}${panelId}`
+}
+
+/** Whether `worktreeId` is a branded ephemeral setup-terminal id. */
+export function isEphemeralSetupTerminalWorktreeId(worktreeId: string): boolean {
+  return worktreeId.startsWith(EPHEMERAL_SETUP_TERMINAL_WORKTREE_ID_PREFIX)
+}