diff --git a/packages/contracts/src/model.test.ts b/packages/contracts/src/model.test.ts
index 137167daa577a9b3aff5e77d9201a805a483c203..c228782960a5e73d806e6e18173a4a9c28baccf6 100644
--- a/packages/contracts/src/model.test.ts
+++ b/packages/contracts/src/model.test.ts
@@ -31,8 +31,11 @@ describe("normalizeModelSlug", () => {
   });
 
   it("uses provider-specific aliases", () => {
-    expect(normalizeModelSlug("sonnet", "claudeCode")).toBe("claude-sonnet-4-5");
-    expect(normalizeModelSlug("opus-4.1", "claudeCode")).toBe("claude-opus-4-1");
+    expect(normalizeModelSlug("sonnet", "claudeCode")).toBe("claude-sonnet-4-6");
+    expect(normalizeModelSlug("opus-4.6", "claudeCode")).toBe("claude-opus-4-6");
+    expect(normalizeModelSlug("claude-haiku-4-5-20251001", "claudeCode")).toBe(
+      "claude-haiku-4-5",
+    );
   });
 });
 
@@ -57,7 +60,7 @@ describe("resolveModelSlug", () => {
     expect(resolveModelSlugForProvider("claudeCode", undefined)).toBe(
       DEFAULT_MODEL_BY_PROVIDER.claudeCode,
     );
-    expect(resolveModelSlugForProvider("claudeCode", "sonnet")).toBe("claude-sonnet-4-5");
+    expect(resolveModelSlugForProvider("claudeCode", "sonnet")).toBe("claude-sonnet-4-6");
     expect(resolveModelSlugForProvider("claudeCode", "gpt-5.3-codex")).toBe(
       DEFAULT_MODEL_BY_PROVIDER.claudeCode,
     );
diff --git a/packages/contracts/src/model.ts b/packages/contracts/src/model.ts
index 3626e4c5a78e256c5c9267148e3227fa9350b84b..39944bd579b304bbe0dbbf256b17bf2bf4326de7 100644
--- a/packages/contracts/src/model.ts
+++ b/packages/contracts/src/model.ts
@@ -13,9 +13,9 @@ export const MODEL_OPTIONS_BY_PROVIDER = {
     { slug: "gpt-5.2", name: "GPT-5.2" },
   ],
   claudeCode: [
-    { slug: "claude-sonnet-4-5", name: "Claude Sonnet 4.5" },
-    { slug: "claude-opus-4-1", name: "Claude Opus 4.1" },
-    { slug: "claude-haiku-3-5", name: "Claude Haiku 3.5" },
+    { slug: "claude-sonnet-4-6", name: "Claude Sonnet 4.6" },
+    { slug: "claude-opus-4-6", name: "Claude Opus 4.6" },
+    { slug: "claude-haiku-4-5", name: "Claude Haiku 4.5" },
   ],
 } as const satisfies Record<ProviderKind, readonly ModelOption[]>;
 
@@ -23,7 +23,7 @@ export type ModelSlug = (typeof MODEL_OPTIONS_BY_PROVIDER)[ProviderKind][number]
 
 export const DEFAULT_MODEL_BY_PROVIDER: Record<ProviderKind, ModelSlug> = {
   codex: "gpt-5.3-codex",
-  claudeCode: "claude-sonnet-4-5",
+  claudeCode: "claude-sonnet-4-6",
 };
 
 // Backward compatibility for existing Codex-only call sites.
@@ -38,15 +38,18 @@ export const MODEL_SLUG_ALIASES_BY_PROVIDER: Record<ProviderKind, Record<string,
     "gpt-5.3-spark": "gpt-5.3-codex-spark",
   },
   claudeCode: {
-    sonnet: "claude-sonnet-4-5",
-    "sonnet-4.5": "claude-sonnet-4-5",
-    "claude-sonnet-4.5": "claude-sonnet-4-5",
-    opus: "claude-opus-4-1",
-    "opus-4.1": "claude-opus-4-1",
-    "claude-opus-4.1": "claude-opus-4-1",
-    haiku: "claude-haiku-3-5",
-    "haiku-3.5": "claude-haiku-3-5",
-    "claude-haiku-3.5": "claude-haiku-3-5",
+    sonnet: "claude-sonnet-4-6",
+    "sonnet-4.6": "claude-sonnet-4-6",
+    "claude-sonnet-4.6": "claude-sonnet-4-6",
+    "claude-sonnet-4-6-20251117": "claude-sonnet-4-6",
+    opus: "claude-opus-4-6",
+    "opus-4.6": "claude-opus-4-6",
+    "claude-opus-4.6": "claude-opus-4-6",
+    "claude-opus-4-6-20251117": "claude-opus-4-6",
+    haiku: "claude-haiku-4-5",
+    "haiku-4.5": "claude-haiku-4-5",
+    "claude-haiku-4.5": "claude-haiku-4-5",
+    "claude-haiku-4-5-20251001": "claude-haiku-4-5",
   },
 };
 
diff --git a/packages/contracts/src/provider.test.ts b/packages/contracts/src/provider.test.ts
index 9242b42c423a89700a28cfd0c8ea2cd31ef5c336..6dc873ced8a6f68369f5bc74de33bda21c6c718a 100644
--- a/packages/contracts/src/provider.test.ts
+++ b/packages/contracts/src/provider.test.ts
@@ -28,7 +28,7 @@ describe("ProviderSessionStartInput", () => {
     const parsed = decodeProviderSessionStartInput({
       provider: "claudeCode",
       cwd: "/tmp/workspace",
-      model: "claude-sonnet-4-5",
+      model: "claude-sonnet-4-6",
       providerOptions: {
         claudeCode: {
           binaryPath: "/usr/local/bin/claude",