refactor: simplify reasoning policy to minimal checks

Just three simple startsWith/includes checks for special models.
No config files, no helper functions, no complexity.

- Grok models: binary on/off reasoning
- GPT-5 Pro: always high
- Gemini 3: limited levels
- Everything else: check models.json or default to all levels

Author: kylecarbs

src/browser/utils/thinking/policy.test.ts

@@ -52,11 +52,11 @@ describe("getThinkingPolicyForModel", () => {
     expect(getThinkingPolicyForModel("xai:grok-beta")).toEqual(["off", "high"]);
   });
 
-  test("grok models with version suffixes match config prefix", () => {
+  test("grok models with version suffixes also get binary policy", () => {
     expect(getThinkingPolicyForModel("xai:grok-4-1-fast-v2")).toEqual(["off", "high"]);
   });
 
-  test("unknown xAI models get default policy", () => {
+  test("grok-code does not match grok- prefix, gets default policy", () => {
     expect(getThinkingPolicyForModel("xai:grok-code-fast-1")).toEqual([
       "off",
       "low",

src/browser/utils/thinking/policy.ts

@@ -13,7 +13,6 @@
  */
 
 import type { ThinkingLevel } from "@/common/types/thinking";
-import { getReasoningConfig } from "@/common/constants/reasoning-config";
 import modelsData from "@/common/utils/tokens/models.json";
 
 /**
@@ -47,26 +46,30 @@ function getModelMetadata(modelString: string): Record<string, unknown> | null {
 
 /**
  * Returns the thinking policy for a given model.
- *
- * Rules:
- * 1. Check reasoning-config.ts for explicit model policies
- * 2. Check models.json for supports_reasoning: false → ["off"]
- * 3. Default → ["off", "low", "medium", "high"]
  */
 export function getThinkingPolicyForModel(modelString: string): ThinkingPolicy {
-  // Check explicit config first
-  const config = getReasoningConfig(modelString);
-  if (config) {
-    return config;
+  // GPT-5 Pro: always high
+  if (modelString.startsWith("openai:gpt-5-pro")) {
+    return ["high"];
+  }
+
+  // Gemini 3: limited levels
+  if (modelString.includes("gemini-3")) {
+    return ["low", "high"];
+  }
+
+  // Grok: binary on/off (but not grok-code)
+  if (modelString.startsWith("xai:grok-") && !modelString.includes("grok-code")) {
+    return ["off", "high"];
   }
 
-  // Check models.json for models that don't support reasoning
+  // Check models.json for no reasoning support
   const metadata = getModelMetadata(modelString);
   if (metadata?.supports_reasoning === false) {
     return ["off"];
   }
 
-  // Default: all levels selectable
+  // Default: all levels
   return ["off", "low", "medium", "high"];
 }