refactor(agents): replace per-version GPT checks with regex pattern

Replace isGpt5_4Model + isGpt5_5Model + OR-composed isGptNativeSisyphusModel
with a single regex matching GPT-5.x where x >= 4. Automatically covers
future versions (5.6, 5.7, 5.10+) without code changes.

Constraint: Must continue to reject gpt-5.3-codex and gpt-5.x where x < 4
Rejected: Per-version functions | not scalable, each new version adds a function + OR clause
Confidence: high
Scope-risk: narrow

src/agents/types.test.ts

@@ -3,68 +3,44 @@ import {
   isGptModel,
   isGeminiModel,
   isGlmModel,
-  isGpt5_4Model,
-  isGpt5_5Model,
   isGptNativeSisyphusModel,
   isMiniMaxModel,
 } from "./types";
 
-describe("isGpt5_4Model", () => {
-  test("detects gpt-5.4 models", () => {
-    expect(isGpt5_4Model("openai/gpt-5.4")).toBe(true);
-    expect(isGpt5_4Model("openai/gpt-5-4")).toBe(true);
-    expect(isGpt5_4Model("openai/gpt-5.4-codex")).toBe(true);
-    expect(isGpt5_4Model("github-copilot/gpt-5.4")).toBe(true);
-    expect(isGpt5_4Model("venice/gpt-5-4")).toBe(true);
-  });
-
-  test("does not match other GPT models", () => {
-    expect(isGpt5_4Model("openai/gpt-5.3-codex")).toBe(false);
-    expect(isGpt5_4Model("openai/gpt-5.1")).toBe(false);
-    expect(isGpt5_4Model("openai/gpt-4o")).toBe(false);
-    expect(isGpt5_4Model("github-copilot/gpt-4o")).toBe(false);
-  });
-
-  test("does not match non-GPT models", () => {
-    expect(isGpt5_4Model("anthropic/claude-opus-4-7")).toBe(false);
-    expect(isGpt5_4Model("google/gemini-3.1-pro")).toBe(false);
-    expect(isGpt5_4Model("openai/o1")).toBe(false);
-  });
-});
-
-describe("isGpt5_5Model", () => {
-  test("detects gpt-5.5 models", () => {
-    expect(isGpt5_5Model("gpt-5.5")).toBe(true);
-    expect(isGpt5_5Model("gpt-5-5")).toBe(true);
-    expect(isGpt5_5Model("openai/gpt-5.5")).toBe(true);
-    expect(isGpt5_5Model("openai/gpt-5-5")).toBe(true);
-    expect(isGpt5_5Model("github-copilot/gpt-5.5")).toBe(true);
-  });
-
-  test("does not match other GPT models", () => {
-    expect(isGpt5_5Model("openai/gpt-5.4")).toBe(false);
-    expect(isGpt5_5Model("openai/gpt-5.3-codex")).toBe(false);
-    expect(isGpt5_5Model("openai/gpt-4o")).toBe(false);
-  });
-
-  test("does not match non-GPT models", () => {
-    expect(isGpt5_5Model("anthropic/claude-opus-4-7")).toBe(false);
-    expect(isGpt5_5Model("google/gemini-3.1-pro")).toBe(false);
-  });
-});
-
 describe("isGptNativeSisyphusModel", () => {
-  test("allows GPT-5.4 and GPT-5.5 variants", () => {
+  test("allows GPT-5.x where x >= 4", () => {
     expect(isGptNativeSisyphusModel("openai/gpt-5.4")).toBe(true);
     expect(isGptNativeSisyphusModel("openai/gpt-5-4")).toBe(true);
     expect(isGptNativeSisyphusModel("openai/gpt-5.5")).toBe(true);
     expect(isGptNativeSisyphusModel("openai/gpt-5-5")).toBe(true);
+    expect(isGptNativeSisyphusModel("openai/gpt-5.9")).toBe(true);
+    expect(isGptNativeSisyphusModel("openai/gpt-5-9")).toBe(true);
+    expect(isGptNativeSisyphusModel("openai/gpt-5.10")).toBe(true);
+    expect(isGptNativeSisyphusModel("openai/gpt-5-10")).toBe(true);
   });
 
-  test("rejects non-native Sisyphus GPT models and non-GPT models", () => {
+  test("allows with various providers and suffixes", () => {
+    expect(isGptNativeSisyphusModel("github-copilot/gpt-5.4")).toBe(true);
+    expect(isGptNativeSisyphusModel("venice/gpt-5-4")).toBe(true);
+    expect(isGptNativeSisyphusModel("openai/gpt-5.4-codex")).toBe(true);
+    expect(isGptNativeSisyphusModel("openai/gpt-5.5-mini")).toBe(true);
+  });
+
+  test("rejects GPT-5.x where x < 4", () => {
     expect(isGptNativeSisyphusModel("openai/gpt-5.3-codex")).toBe(false);
+    expect(isGptNativeSisyphusModel("openai/gpt-5.1")).toBe(false);
+    expect(isGptNativeSisyphusModel("openai/gpt-5-0")).toBe(false);
+  });
+
+  test("rejects other GPT models", () => {
     expect(isGptNativeSisyphusModel("openai/gpt-4o")).toBe(false);
+    expect(isGptNativeSisyphusModel("github-copilot/gpt-4o")).toBe(false);
+  });
+
+  test("rejects non-GPT models", () => {
     expect(isGptNativeSisyphusModel("anthropic/claude-opus-4-7")).toBe(false);
+    expect(isGptNativeSisyphusModel("google/gemini-3.1-pro")).toBe(false);
+    expect(isGptNativeSisyphusModel("openai/o1")).toBe(false);
   });
 });
 

src/agents/types.ts

@@ -79,18 +79,11 @@ export function isGptModel(model: string): boolean {
   return modelName.includes("gpt");
 }
 
-export function isGpt5_4Model(model: string): boolean {
+const GPT_NATIVE_SISYPHUS_RE = /gpt-5[.-](?:[4-9]|\d{2,})/i;
-  const modelName = extractModelName(model).toLowerCase();
-  return modelName.includes("gpt-5.4") || modelName.includes("gpt-5-4");
-}
-
-export function isGpt5_5Model(model: string): boolean {
-  const modelName = extractModelName(model).toLowerCase();
-  return modelName.includes("gpt-5.5") || modelName.includes("gpt-5-5");
-}
 
 export function isGptNativeSisyphusModel(model: string): boolean {
-  return isGpt5_4Model(model) || isGpt5_5Model(model);
+  const modelName = extractModelName(model).toLowerCase();
+  return GPT_NATIVE_SISYPHUS_RE.test(modelName);
 }
 
 export function isGpt5_3CodexModel(model: string): boolean {