fix(pi): start Pi terminal launches on the model picked in the launcher (#41005)

Pi had no launch catalog, so a picked model compiled to no arguments.
A launch-only catalog maps it to `pi --model <provider/id>`. A --model
in Pi's Arguments stays literal: Pi's CLI fuzzy-matches it, while Pi
chats need an exact provider/id.

Co-authored-by: lucas-wu-wakakak <8309814+lucas-wu-wakakak@users.noreply.github.com>

src/shared/agent-launch/choices/agent-choice-args-analysis.ts

@@ -12,20 +12,10 @@ import {
   type AgentStartupShell
 } from '../startup/tui-agent-startup-shell'
 import type { TuiAgent } from '../catalog/tui-agent'
+import type { ChoiceOccurrence } from './agent-launch-choices'
 import { agentChoiceConfigString, agentChoiceConfigValue } from './agent-choice-cli-apply'
 
-export type ChoiceOccurrence = {
-  key: string
-  value: string
-  valueType?: 'string' | 'boolean'
-  source?: boolean
-  words: string[]
-  start: number
-  end: number
-  lift: boolean
-  owned: boolean
-  replacement?: string
-}
+export type { ChoiceOccurrence } from './agent-launch-choices'
 
 /** Every cut uses the original spans and preserves operand roles in its consuming grammar. */
 export function analyzeChoiceArgs(
@@ -137,6 +127,10 @@ export function analyzeChoiceArgs(
             (!inline || name.startsWith('--')) &&
             !!value &&
             !value.startsWith('-')
+          if (form.kind === 'value' && form.recognizes?.(value) === false) {
+            valueType = undefined
+            lift = false
+          }
           if (form.kind === 'settings') {
             const effective = effectiveSettings.get(form)
             if (effective?.index !== index || opaqueKeys.has(key)) {

src/shared/agent-launch/choices/agent-choice-cli-apply.test.ts

@@ -92,3 +92,25 @@ it.each(['true', '42', '["high"]', '{key="high"}'])(
     expect(result.userArgs).toBe(userArgs)
   }
 )
+
+it('keeps a Pi model in Arguments literal so chats never receive a CLI pattern', () => {
+  const lift = (userArgs: string) =>
+    reconcileAgentChoiceArgsDetailed({
+      agent: 'pi',
+      userArgs,
+      choices: {},
+      mode: 'arguments-edit',
+      keys
+    })
+  for (const userArgs of [
+    '--model sonnet:high',
+    '--model anthropic/sonnet',
+    '--model anthropic/claude-opus-5-5',
+    '--provider openai --model gpt-6'
+  ]) {
+    const result = lift(userArgs)
+    expect(result.recognized).toEqual([])
+    expect(result.choices).toEqual({})
+    expect(result.userArgs).toBe(userArgs)
+  }
+})

src/shared/agent-launch/choices/agent-launch-choices.ts

@@ -25,11 +25,31 @@ export function terminalAgentChoices(
 
 export type AgentLaunchChoices = Partial<Record<TuiAgent, AgentModelOptionChoices>>
 export type AgentChoiceCliForm =
-  | { kind: 'value'; names: readonly string[]; lift: 'separate-and-long-equals' | 'never' }
+  | {
+      kind: 'value'
+      names: readonly string[]
+      lift: 'separate-and-long-equals' | 'never'
+      /** Values outside the choice's grammar stay literal arguments instead of becoming choices. */
+      recognizes?: (value: string) => boolean
+    }
   | { kind: 'config'; names: readonly string[]; key: string; lift: 'codex-bare-string' | 'never' }
   | { kind: 'settings'; names: readonly string[]; key: string; lift: 'merged-json' }
   | { kind: 'recipe'; words: readonly string[]; value: AgentPermissionChoice }
 
+/** One choice flag found in free-form agent arguments. */
+export type ChoiceOccurrence = {
+  key: string
+  value: string
+  valueType?: 'string' | 'boolean'
+  source?: boolean
+  words: string[]
+  start: number
+  end: number
+  lift: boolean
+  owned: boolean
+  replacement?: string
+}
+
 export function normalizeAgentModelOptionChoices(
   value: unknown
 ): AgentModelOptionChoices | undefined {

src/shared/agent-launch/startup/tui-agent-startup-session-options.spec.ts

@@ -41,6 +41,20 @@ describe('tui agent startup session options', () => {
     expect(plan?.sessionOptions).toEqual({ model: 'zai-coding-plan/glm-5.3-flash' })
   })
 
+  it('starts Pi on the picked model in place of its configured one', () => {
+    const plan = buildAgentStartupPlan({
+      agent: 'pi',
+      prompt: '',
+      cmdOverrides: {},
+      platform: 'linux',
+      allowEmptyPromptLaunch: true,
+      sessionOptions: { model: 'anthropic/claude-opus-5-5' },
+      sessionOptionsOverrideAgentArgs: true,
+      agentArgs: '--model openai/gpt-6 --no-skills'
+    })
+    expect(plan?.launchCommand).toBe("pi '--no-skills' '--model' 'anthropic/claude-opus-5-5'")
+  })
+
   it('rejects conflicting singleton flags in an agent command override', () => {
     expect(
       resolveAgentLaunchCommand({

src/shared/agent-session/options/agent-session-option-catalog-pi.ts

@@ -0,0 +1,21 @@
+import { agentChoiceCliApply } from '../../agent-launch/choices/agent-choice-cli-apply'
+import type { AgentSessionOptionCatalog } from './agent-session-option-catalog-types'
+
+// Why: terminal launches need Pi's `--model`; Pi chats keep applying picks over RPC.
+export const PI_LAUNCH_OPTION_CATALOG: AgentSessionOptionCatalog = {
+  // Pi models depend on configured providers; ids are opaque `provider/id` selectors.
+  models: [],
+  modelApply: agentChoiceCliApply(
+    'pi',
+    [
+      {
+        kind: 'value',
+        names: ['--model'],
+        lift: 'separate-and-long-equals',
+        // Pi's CLI fuzzy-matches `--model`; chats need exact ids, so Arguments never become a model choice.
+        recognizes: () => false
+      }
+    ],
+    '--model'
+  )
+}

src/shared/agent-session/options/agent-session-option-catalog.ts

@@ -13,6 +13,7 @@ import {
 import { GROK_SESSION_OPTION_CATALOG } from './agent-session-option-catalog-grok'
 import { MUSE_SESSION_OPTION_CATALOG } from './agent-session-option-catalog-muse'
 import { OMP_SESSION_OPTION_CATALOG } from './agent-session-option-catalog-omp'
+import { PI_LAUNCH_OPTION_CATALOG } from './agent-session-option-catalog-pi'
 import type {
   AgentSessionOptionCatalog,
   AgentSessionOptionCatalogMap,
@@ -91,5 +92,9 @@ export function sessionOptionValueIsValid(value: unknown): value is SessionOptio
 export function getAgentSessionOptionLaunchCatalog(
   agent: AgentType
 ): AgentSessionOptionCatalog | null {
-  return agent === 'opencode' ? OPENCODE_LAUNCH_OPTION_CATALOG : getAgentSessionOptionCatalog(agent)
+  return agent === 'opencode'
+    ? OPENCODE_LAUNCH_OPTION_CATALOG
+    : agent === 'pi'
+      ? PI_LAUNCH_OPTION_CATALOG
+      : getAgentSessionOptionCatalog(agent)
 }