From 6d52e88b33e2d9a41a0cd65106f5914fd2d57cd8 Mon Sep 17 00:00:00 2001
From: Thomas Kosiewski <tk@coder.com>
Date: Fri, 12 Dec 2025 13:48:12 +0100
Subject: [PATCH] =?UTF-8?q?=F0=9F=A4=96=20fix:=20enable=20xhigh=20thinking?=
 =?UTF-8?q?=20for=20gpt-5.2?=
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Change-Id: I7af560b6693e4dc4364c98bc98eca70f3822534b
Signed-off-by: Thomas Kosiewski <tk@coder.com>
---
 src/browser/utils/thinking/policy.test.ts | 44 +++++++++++++++++++++++
 src/browser/utils/thinking/policy.ts      | 10 ++++--
 src/common/types/thinking.ts              |  2 +-
 src/common/utils/tokens/models-extra.ts   |  1 +
 4 files changed, 54 insertions(+), 3 deletions(-)

diff --git a/src/browser/utils/thinking/policy.test.ts b/src/browser/utils/thinking/policy.test.ts
index 4e259c0306..0fe7bc27b2 100644
--- a/src/browser/utils/thinking/policy.test.ts
+++ b/src/browser/utils/thinking/policy.test.ts
@@ -64,6 +64,36 @@ describe("getThinkingPolicyForModel", () => {
     ]);
   });
 
+  test("returns 5 levels including xhigh for gpt-5.2", () => {
+    expect(getThinkingPolicyForModel("openai:gpt-5.2")).toEqual([
+      "off",
+      "low",
+      "medium",
+      "high",
+      "xhigh",
+    ]);
+  });
+
+  test("returns 5 levels including xhigh for gpt-5.2 behind mux-gateway", () => {
+    expect(getThinkingPolicyForModel("mux-gateway:openai/gpt-5.2")).toEqual([
+      "off",
+      "low",
+      "medium",
+      "high",
+      "xhigh",
+    ]);
+  });
+
+  test("returns 5 levels including xhigh for gpt-5.2 with version suffix", () => {
+    expect(getThinkingPolicyForModel("openai:gpt-5.2-2025-12-11")).toEqual([
+      "off",
+      "low",
+      "medium",
+      "high",
+      "xhigh",
+    ]);
+  });
+
   test("returns 5 levels including xhigh for gpt-5.1-codex-max behind mux-gateway", () => {
     expect(getThinkingPolicyForModel("mux-gateway:openai/gpt-5.1-codex-max")).toEqual([
       "off",
@@ -205,6 +235,20 @@ describe("enforceThinkingPolicy", () => {
     });
   });
 
+  describe("GPT-5.2 (5 levels including xhigh)", () => {
+    test("allows xhigh for base model", () => {
+      expect(enforceThinkingPolicy("openai:gpt-5.2", "xhigh")).toBe("xhigh");
+    });
+
+    test("allows xhigh behind mux-gateway", () => {
+      expect(enforceThinkingPolicy("mux-gateway:openai/gpt-5.2", "xhigh")).toBe("xhigh");
+    });
+
+    test("allows xhigh for versioned model", () => {
+      expect(enforceThinkingPolicy("openai:gpt-5.2-2025-12-11", "xhigh")).toBe("xhigh");
+    });
+  });
+
   describe("xhigh fallback for non-codex-max models", () => {
     test("falls back to medium when xhigh requested on standard model", () => {
       // Standard models don't support xhigh, so fall back to medium (preferred fallback)
diff --git a/src/browser/utils/thinking/policy.ts b/src/browser/utils/thinking/policy.ts
index 7bcfcac869..3fd3fbafd0 100644
--- a/src/browser/utils/thinking/policy.ts
+++ b/src/browser/utils/thinking/policy.ts
@@ -25,10 +25,11 @@ export type ThinkingPolicy = readonly ThinkingLevel[];
  *
  * Rules:
  * - openai:gpt-5.1-codex-max → ["off", "low", "medium", "high", "xhigh"] (5 levels including xhigh)
+ * - openai:gpt-5.2 → ["off", "low", "medium", "high", "xhigh"] (5 levels including xhigh)
  * - openai:gpt-5.2-pro → ["medium", "high", "xhigh"] (3 levels)
  * - openai:gpt-5-pro → ["high"] (only supported level, legacy)
  * - gemini-3 → ["low", "high"] (thinking level only)
- * - default → ["off", "low", "medium", "high"] (standard 4 levels)
+ * - default → ["off", "low", "medium", "high"] (standard 4 levels; xhigh is opt-in per model)
  *
  * Tolerates version suffixes (e.g., gpt-5-pro-2025-10-06).
  * Does NOT match gpt-5-pro-mini (uses negative lookahead).
@@ -55,6 +56,11 @@ export function getThinkingPolicyForModel(modelString: string): ThinkingPolicy {
     return ["medium", "high", "xhigh"];
   }
 
+  // gpt-5.2 supports 5 reasoning levels including xhigh (Extra High)
+  if (/^gpt-5\.2(?!-[a-z])/.test(withoutProviderNamespace)) {
+    return ["off", "low", "medium", "high", "xhigh"];
+  }
+
   // gpt-5-pro (legacy) only supports high
   if (/^gpt-5-pro(?!-[a-z])/.test(withoutProviderNamespace)) {
     return ["high"];
@@ -65,7 +71,7 @@ export function getThinkingPolicyForModel(modelString: string): ThinkingPolicy {
     return ["low", "high"];
   }
 
-  // Default policy: standard 4 levels (xhigh only for codex-max)
+  // Default policy: standard 4 levels (off/low/medium/high). Models with xhigh must opt in above.
   return ["off", "low", "medium", "high"];
 }
 
diff --git a/src/common/types/thinking.ts b/src/common/types/thinking.ts
index a30d258793..0b820144e8 100644
--- a/src/common/types/thinking.ts
+++ b/src/common/types/thinking.ts
@@ -68,7 +68,7 @@ export const OPENAI_REASONING_EFFORT: Record<ThinkingLevel, string | undefined>
   low: "low",
   medium: "medium",
   high: "high",
-  xhigh: "xhigh", // Extra High - only supported by gpt-5.1-codex-max
+  xhigh: "xhigh", // Extra High - supported by models that expose xhigh (e.g., gpt-5.1-codex-max, gpt-5.2)
 };
 
 /**
diff --git a/src/common/utils/tokens/models-extra.ts b/src/common/utils/tokens/models-extra.ts
index 9d24f7abe9..3863a4b2b7 100644
--- a/src/common/utils/tokens/models-extra.ts
+++ b/src/common/utils/tokens/models-extra.ts
@@ -43,6 +43,7 @@ export const modelsExtra: Record<string, ModelData> = {
   // GPT-5.2 - Released December 11, 2025
   // $1.75/M input, $14/M output
   // Cached input: $0.175/M
+  // Supports off, low, medium, high, xhigh reasoning levels
   "gpt-5.2": {
     max_input_tokens: 400000,
     max_output_tokens: 128000,