feat(librarian): conditionally enable thinking based on model type

- Add isGeminiModel helper to detect Gemini models
- Disable thinking config for Gemini models (not supported)
- Enable thinking with 32000 token budget for other models
- Add tests verifying both Gemini and Claude behavior

🤖 Generated with assistance of OhMyOpenCode

src/agents/librarian.ts

@@ -1,5 +1,6 @@
 import type { AgentConfig } from "@opencode-ai/sdk"
 import type { AgentPromptMetadata } from "./types"
+import { isGeminiModel } from "./types"
 import { createAgentToolRestrictions } from "../shared/permission-compat"
 
 export const LIBRARIAN_PROMPT_METADATA: AgentPromptMetadata = {
@@ -28,7 +29,7 @@ export function createLibrarianAgent(model: string): AgentConfig {
     "call_omo_agent",
   ])
 
-  return {
+  const base = {
     description:
       "Specialized codebase understanding agent for multi-repository analysis, searching remote codebases, retrieving official documentation, and finding implementation examples using GitHub CLI, Context7, and Web Search. MUST BE USED when users ask to look up code in remote repositories, explain library internals, or find usage examples in open source.",
     mode: "subagent" as const,
@@ -322,5 +323,11 @@ grep_app_searchGitHub(query: "useQuery")
 
 `,
   }
+
+  if (isGeminiModel(model)) {
+    return base
+  }
+
+  return { ...base, thinking: { type: "enabled", budgetTokens: 32000 } }
 }