fix: respect Kiro default agent fallback

src/hooks/useAiAgentPreferences.test.ts

@@ -18,6 +18,7 @@ const aiAgentsStatus = {
   opencode: { status: 'missing' as const, version: null },
   pi: { status: 'missing' as const, version: null },
   gemini: { status: 'missing' as const, version: null },
+  kiro: { status: 'missing' as const, version: null },
 }
 
 describe('useAiAgentPreferences', () => {
@@ -86,6 +87,7 @@ describe('useAiAgentPreferences', () => {
         opencode: { status: 'missing', version: null },
         pi: { status: 'missing', version: null },
         gemini: { status: 'missing', version: null },
+        kiro: { status: 'missing', version: null },
       },
     }))
 

src/lib/aiTargets.test.ts

@@ -59,6 +59,32 @@ describe('ai target provider contract', () => {
     })
   })
 
+  it('accepts legacy agent ids saved in the default target field', () => {
+    const target = resolveAiTarget({
+      default_ai_agent: 'claude_code',
+      default_ai_target: 'kiro',
+    } as Settings)
+
+    expect(target).toMatchObject({
+      kind: 'agent',
+      agent: 'kiro',
+      id: 'agent:kiro',
+    })
+  })
+
+  it('uses the legacy default agent when a saved agent target is stale', () => {
+    const target = resolveAiTarget({
+      default_ai_agent: 'kiro',
+      default_ai_target: 'agent:claude_code',
+    } as Settings)
+
+    expect(target).toMatchObject({
+      kind: 'agent',
+      agent: 'kiro',
+      id: 'agent:kiro',
+    })
+  })
+
   it('keeps provider defaults in one catalog with stable grouping metadata', () => {
     const entries = aiModelProviderCatalog()
     const kinds = entries.map((entry) => entry.kind)

src/lib/aiTargets.ts

@@ -125,11 +125,16 @@ export function agentTargets(): AiTarget[] {
 export function resolveAiTarget(settings: Settings): AiTarget {
   const providers = normalizeAiModelProviders(settings.ai_model_providers)
   const targets = [...agentTargets(), ...configuredModelTargets(providers)]
-  const storedTarget = settings.default_ai_target
-  const target = targets.find((candidate) => candidate.id === storedTarget)
-  if (target) return target
+  const storedLegacyAgent = normalizeStoredAiAgent(settings.default_ai_agent)
+  const legacyAgent = storedLegacyAgent ?? DEFAULT_AI_AGENT
+  const target = resolveStoredAiTarget(settings.default_ai_target, targets)
+  if (target) {
+    if (target.kind === 'agent' && storedLegacyAgent && target.agent === DEFAULT_AI_AGENT && target.agent !== storedLegacyAgent) {
+      return agentTargets().find((candidate) => candidate.kind === 'agent' && candidate.agent === legacyAgent) ?? target
+    }
+    return target
+  }
 
-  const legacyAgent = normalizeStoredAiAgent(settings.default_ai_agent) ?? DEFAULT_AI_AGENT
   return agentTargets().find((candidate) => candidate.kind === 'agent' && candidate.agent === legacyAgent) ?? agentTargets()[0]
 }
 
@@ -137,6 +142,18 @@ export function targetAgent(target: AiTarget): AiAgentId {
   return target.kind === 'agent' ? target.agent : DEFAULT_AI_AGENT
 }
 
+function resolveStoredAiTarget(storedTarget: string | null | undefined, targets: AiTarget[]): AiTarget | null {
+  const target = storedTarget?.trim()
+  if (!target) return null
+
+  const exactTarget = targets.find((candidate) => candidate.id === target)
+  if (exactTarget) return exactTarget
+
+  const legacyAgent = normalizeStoredAiAgent(target)
+  if (!legacyAgent) return null
+  return targets.find((candidate) => candidate.kind === 'agent' && candidate.agent === legacyAgent) ?? null
+}
+
 export function normalizeAiModelProviders(providers: AiModelProvider[] | null | undefined): AiModelProvider[] {
   return (providers ?? []).map(normalizeAiModelProvider).filter((provider): provider is AiModelProvider => provider !== null)
 }