refactor(shared): derive WellKnownAgentType from TuiAgent

The hand-written 22-member WellKnownAgentType union was a stale copy of the
launchable-agent list, 15 members behind TuiAgent: aug, autohand,
claude-agent-teams, cline, codebuff, continue, crush, goose, kilo, kimi, kiro,
mistral-vibe, openclaw, qwen-code, rovo. All 21 non-'unknown' members it did
carry were already TuiAgent members, so the union is now derived
(`TuiAgent | 'unknown'`) and cannot drift again.

'unknown' stays outside TuiAgent: it is the "no agent identified yet" sentinel,
not a launchable agent.

AgentType is structurally unchanged. `(string & {})` absorbs the union, so
AgentType was and remains `string` — this is a documentation/staleness fix with
no behaviour change and zero consumers affected (WellKnownAgentType had none
repo-wide beyond the AgentType alias itself).

tui-agent.ts is a pure type union with no imports, so this adds no cycle.

Adds a type-level coverage test that fails to compile if anyone reverts to a
hand-written list.

src/shared/agent-status-types.test.ts

@@ -15,6 +15,8 @@ import {
   AGENT_STATUS_STATES,
   AGENT_TYPE_MAX_LENGTH
 } from './agent-status-types'
+import type { AgentType, WellKnownAgentType } from './agent-status-types'
+import type { TuiAgent } from './tui-agent'
 
 afterEach(() => {
   vi.restoreAllMocks()
@@ -674,3 +676,32 @@ describe('normalizeAgentStatusPayload matches the JSON round trip', () => {
     }
   })
 })
+
+describe('WellKnownAgentType', () => {
+  // Compile-time proof the union is derived from TuiAgent rather than hand-copied:
+  // a literal list that misses any launchable agent id fails to typecheck here.
+  const widenTuiAgent = (agent: TuiAgent): WellKnownAgentType => agent
+
+  it('covers every TuiAgent id plus the unknown sentinel', () => {
+    // ids the previous 22-member hand-written union had drifted past
+    const formerlyMissing: WellKnownAgentType[] = [
+      'qwen-code',
+      'mistral-vibe',
+      'claude-agent-teams'
+    ]
+    const sentinel: WellKnownAgentType = 'unknown'
+
+    expect([...formerlyMissing, sentinel, widenTuiAgent('rovo')]).toEqual([
+      'qwen-code',
+      'mistral-vibe',
+      'claude-agent-teams',
+      'unknown',
+      'rovo'
+    ])
+  })
+
+  it('keeps AgentType open to custom agent names', () => {
+    const custom: AgentType = 'some-in-house-agent'
+    expect(custom).toBe('some-in-house-agent')
+  })
+})

src/shared/agent-status-types.ts

@@ -5,6 +5,7 @@
 import type { AgentProviderSessionMetadata } from './agent-session-resume'
 import type { OrchestrationFleetAttention } from './orchestration-fleet-attention'
 import type { AgentStatusRowFacets } from './agent-status-observation'
+import type { TuiAgent } from './tui-agent'
 import {
   normalizeInteractivePromptField,
   normalizeOptionalField,
@@ -26,30 +27,9 @@ export const AGENT_STATUS_STATES = ['working', 'blocked', 'waiting', 'done'] as
 export type AgentStatusState = (typeof AGENT_STATUS_STATES)[number]
 export type AgentWorkingMode = 'monitoring'
 // Why: agent types aren't a fixed set (custom agents exist); any non-empty string is
-// accepted — these well-known names are just a convenience union for pattern-matching.
-export type WellKnownAgentType =
-  | 'claude'
-  | 'openclaude'
-  | 'codex'
-  | 'gemini'
-  | 'antigravity'
-  | 'amp'
-  | 'opencode'
-  | 'mimo-code'
-  | 'cursor'
-  | 'copilot'
-  | 'aider'
-  | 'pi'
-  | 'omp'
-  | 'prime-agent'
-  | 'droid'
-  | 'command-code'
-  | 'grok'
-  | 'hermes'
-  | 'devin'
-  | 'ante'
-  | 'trae'
-  | 'unknown'
+// accepted — the well-known names are the launchable TuiAgent ids plus the 'unknown'
+// sentinel (no agent identified yet), a convenience union for pattern-matching.
+export type WellKnownAgentType = TuiAgent | 'unknown'
 export type AgentType = WellKnownAgentType | (string & {})
 
 /** A snapshot of a previous agent state, used to render activity blocks.