diff --git a/packages/server/src/server/agent/agent-sdk-types.ts b/packages/server/src/server/agent/agent-sdk-types.ts
index 5f3caad67..e6ff7339a 100644
--- a/packages/server/src/server/agent/agent-sdk-types.ts
+++ b/packages/server/src/server/agent/agent-sdk-types.ts
@@ -71,6 +71,15 @@ export interface AgentSelectOption {
   metadata?: AgentMetadata;
 }
 
+export function normalizeAgentModelDefinition(model: AgentModelDefinition): AgentModelDefinition {
+  const defaultThinkingOptionId =
+    model.defaultThinkingOptionId ?? model.thinkingOptions?.find((option) => option.isDefault)?.id;
+  if (!defaultThinkingOptionId || defaultThinkingOptionId === model.defaultThinkingOptionId) {
+    return model;
+  }
+  return { ...model, defaultThinkingOptionId };
+}
+
 export interface ProviderSnapshotEntry {
   provider: AgentProvider;
   status: ProviderStatus;
diff --git a/packages/server/src/server/agent/provider-registry.test.ts b/packages/server/src/server/agent/provider-registry.test.ts
index ade0d34e4..c6f507b3e 100644
--- a/packages/server/src/server/agent/provider-registry.test.ts
+++ b/packages/server/src/server/agent/provider-registry.test.ts
@@ -755,6 +755,45 @@ describe("model merging", () => {
     ]);
   });
 
+  test("profile thinking option default is normalized onto the model", async () => {
+    const registry = buildProviderRegistry(logger, {
+      providerOverrides: {
+        codex: {
+          models: [
+            {
+              id: "profile-default",
+              label: "Profile Default",
+              isDefault: true,
+              thinkingOptions: [
+                { id: "off", label: "Off" },
+                { id: "max", label: "Max", isDefault: true },
+              ],
+            },
+          ],
+        },
+      },
+    });
+
+    const models = await registry.codex.fetchModels({
+      cwd: "/tmp/registry-models",
+      force: false,
+    });
+
+    expect(models).toEqual([
+      {
+        provider: "codex",
+        id: "profile-default",
+        label: "Profile Default",
+        isDefault: true,
+        thinkingOptions: [
+          { id: "off", label: "Off" },
+          { id: "max", label: "Max", isDefault: true },
+        ],
+        defaultThinkingOptionId: "max",
+      },
+    ]);
+  });
+
   test("additional models append to runtime models", async () => {
     mockState.runtimeModels.set("claude", [
       {
diff --git a/packages/server/src/server/agent/provider-registry.ts b/packages/server/src/server/agent/provider-registry.ts
index d2d0cb5b4..1af17a12d 100644
--- a/packages/server/src/server/agent/provider-registry.ts
+++ b/packages/server/src/server/agent/provider-registry.ts
@@ -14,6 +14,7 @@ import type {
   ListPersistedAgentsOptions,
   PersistedAgentDescriptor,
 } from "./agent-sdk-types.js";
+import { normalizeAgentModelDefinition } from "./agent-sdk-types.js";
 import type { WorkspaceGitService } from "../workspace-git-service.js";
 import type {
   AgentProviderRuntimeSettingsMap,
@@ -263,11 +264,11 @@ function mapPersistedAgentDescriptor(
   };
 }
 
-function mapModel(provider: AgentProvider, model: AgentModelDefinition): AgentModelDefinition {
-  return {
-    ...model,
-    provider,
-  };
+function mapModel(
+  provider: AgentProvider,
+  model: AgentModelDefinition | ProviderProfileModel,
+): AgentModelDefinition {
+  return normalizeAgentModelDefinition({ ...model, provider });
 }
 
 function mergeModels(
@@ -281,10 +282,7 @@ function mergeModels(
   if (profileModels.length > 0 && options?.profileModelsAreAdditive !== true) {
     return mergeModelAdditions(
       provider,
-      profileModels.map((model) => ({
-        ...model,
-        provider,
-      })),
+      profileModels.map((model) => mapModel(provider, model)),
       additionalModels,
     );
   }
@@ -305,10 +303,7 @@ function mergeModelAdditions(
   let hasAdditionalDefault = false;
 
   for (const model of modelAdditions) {
-    const additionalModel = {
-      ...model,
-      provider,
-    };
+    const additionalModel = mapModel(provider, model);
     hasAdditionalDefault ||= additionalModel.isDefault === true;
 
     const existingIndex = mergedModels.findIndex((candidate) => candidate.id === model.id);
diff --git a/packages/server/src/shared/messages.providers-snapshot.test.ts b/packages/server/src/shared/messages.providers-snapshot.test.ts
index fac33940a..1b066062d 100644
--- a/packages/server/src/shared/messages.providers-snapshot.test.ts
+++ b/packages/server/src/shared/messages.providers-snapshot.test.ts
@@ -38,6 +38,39 @@ describe("provider snapshot message schemas", () => {
     expect(parsed.enabled).toBe(true);
   });
 
+  test("normalizes thinking option defaults on provider snapshot models", () => {
+    const parsed = ProviderSnapshotEntrySchema.parse({
+      provider: "claude",
+      status: "ready",
+      models: [
+        {
+          provider: "claude",
+          id: "MiniMax-M2.7",
+          label: "MiniMax-M2.7",
+          isDefault: true,
+          thinkingOptions: [
+            { id: "off", label: "Off" },
+            { id: "max", label: "Max", isDefault: true },
+          ],
+        },
+      ],
+    });
+
+    expect(parsed.models).toEqual([
+      {
+        provider: "claude",
+        id: "MiniMax-M2.7",
+        label: "MiniMax-M2.7",
+        isDefault: true,
+        thinkingOptions: [
+          { id: "off", label: "Off" },
+          { id: "max", label: "Max", isDefault: true },
+        ],
+        defaultThinkingOptionId: "max",
+      },
+    ]);
+  });
+
   test("defaults missing enabled state in providers snapshot response entries", () => {
     const parsed = GetProvidersSnapshotResponseMessageSchema.parse({
       type: "get_providers_snapshot_response",
diff --git a/packages/server/src/shared/messages.ts b/packages/server/src/shared/messages.ts
index 30b5811a2..c2799619e 100644
--- a/packages/server/src/shared/messages.ts
+++ b/packages/server/src/shared/messages.ts
@@ -3,7 +3,10 @@ import { CLIENT_CAPS } from "./client-capabilities.js";
 import { AGENT_LIFECYCLE_STATUSES } from "./agent-lifecycle.js";
 import { MAX_EXPLICIT_AGENT_TITLE_CHARS } from "../server/agent/agent-title-limits.js";
 import { AgentProviderSchema } from "../server/agent/provider-manifest.js";
-import { TOOL_CALL_ICON_NAMES } from "../server/agent/agent-sdk-types.js";
+import {
+  normalizeAgentModelDefinition,
+  TOOL_CALL_ICON_NAMES,
+} from "../server/agent/agent-sdk-types.js";
 import {
   ChatCreateRequestSchema,
   ChatListRequestSchema,
@@ -194,16 +197,18 @@ export const AgentFeatureSchema = z.discriminatedUnion("type", [
   AgentFeatureSelectSchema,
 ]);
 
-const AgentModelDefinitionSchema: z.ZodType<AgentModelDefinition> = z.object({
-  provider: AgentProviderSchema,
-  id: z.string(),
-  label: z.string(),
-  description: z.string().optional(),
-  isDefault: z.boolean().optional(),
-  metadata: z.record(z.unknown()).optional(),
-  thinkingOptions: z.array(AgentSelectOptionSchema).optional(),
-  defaultThinkingOptionId: z.string().optional(),
-});
+const AgentModelDefinitionSchema: z.ZodType<AgentModelDefinition> = z
+  .object({
+    provider: AgentProviderSchema,
+    id: z.string(),
+    label: z.string(),
+    description: z.string().optional(),
+    isDefault: z.boolean().optional(),
+    metadata: z.record(z.unknown()).optional(),
+    thinkingOptions: z.array(AgentSelectOptionSchema).optional(),
+    defaultThinkingOptionId: z.string().optional(),
+  })
+  .transform(normalizeAgentModelDefinition);
 
 export const ProviderSnapshotEntrySchema = z.object({
   provider: AgentProviderSchema,