diff --git a/docs/configuration.md b/docs/configuration.md
index 50ae79817..9b6b67ae3 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -29,7 +29,7 @@ Main project configuration using a **flat resource model**. Agents, memories, an
       "build": "CodeZip",
       "entrypoint": "main.py",
       "codeLocation": "app/MyAgent/",
-      "runtimeVersion": "PYTHON_3_12"
+      "runtimeVersion": "PYTHON_3_13"
     }
   ],
   "memories": [
@@ -187,7 +187,7 @@ on the next deployment.
   "build": "CodeZip",
   "entrypoint": "main.py",
   "codeLocation": "app/MyAgent/",
-  "runtimeVersion": "PYTHON_3_12",
+  "runtimeVersion": "PYTHON_3_13",
   "networkMode": "PUBLIC",
   "envVars": [{ "name": "MY_VAR", "value": "my-value" }],
   "instrumentation": {
diff --git a/docs/container-builds.md b/docs/container-builds.md
index de4e20071..cd3cdc154 100644
--- a/docs/container-builds.md
+++ b/docs/container-builds.md
@@ -59,7 +59,7 @@ In `agentcore.json`, set `"build": "Container"`:
   "build": "Container",
   "entrypoint": "main.py",
   "codeLocation": "app/MyAgent/",
-  "runtimeVersion": "PYTHON_3_12"
+  "runtimeVersion": "PYTHON_3_13"
 }
 ```
 
diff --git a/src/cli/operations/agent/generate/__tests__/schema-mapper.test.ts b/src/cli/operations/agent/generate/__tests__/schema-mapper.test.ts
index 29dac9bbc..2eba934a5 100644
--- a/src/cli/operations/agent/generate/__tests__/schema-mapper.test.ts
+++ b/src/cli/operations/agent/generate/__tests__/schema-mapper.test.ts
@@ -88,7 +88,7 @@ describe('mapGenerateConfigToAgent', () => {
     expect(result.name).toBe('TestProject');
     expect(result.build).toBe('CodeZip');
     expect(result.entrypoint).toBe('main.py');
-    expect(result.runtimeVersion).toBe('PYTHON_3_12');
+    expect(result.runtimeVersion).toBe('PYTHON_3_13');
     expect(result.networkMode).toBe('PUBLIC');
     expect(result.protocol).toBe('HTTP');
   });
diff --git a/src/cli/primitives/AgentPrimitive.tsx b/src/cli/primitives/AgentPrimitive.tsx
index 4af6449f4..9d2adc0e3 100644
--- a/src/cli/primitives/AgentPrimitive.tsx
+++ b/src/cli/primitives/AgentPrimitive.tsx
@@ -397,7 +397,7 @@ export class AgentPrimitive extends BasePrimitive<AddAgentOptions, RemovableReso
       build: options.buildType,
       entrypoint: (options.entrypoint ?? 'main.py') as FilePath,
       codeLocation: codeLocation as DirectoryPath,
-      runtimeVersion: 'PYTHON_3_12',
+      runtimeVersion: 'PYTHON_3_13',
       protocol,
       networkMode,
       ...(networkMode === 'VPC' &&
diff --git a/src/cli/tui/screens/agent/types.ts b/src/cli/tui/screens/agent/types.ts
index bb8eaea10..d9070741c 100644
--- a/src/cli/tui/screens/agent/types.ts
+++ b/src/cli/tui/screens/agent/types.ts
@@ -162,5 +162,5 @@ export const NETWORK_MODE_OPTIONS = [
   { id: 'VPC', title: 'VPC', description: 'Attach to your VPC' },
 ] as const;
 
-export const DEFAULT_PYTHON_VERSION: PythonRuntime = 'PYTHON_3_12';
+export const DEFAULT_PYTHON_VERSION: PythonRuntime = 'PYTHON_3_13';
 export const DEFAULT_ENTRYPOINT = 'main.py';
diff --git a/src/cli/tui/screens/generate/defaults.ts b/src/cli/tui/screens/generate/defaults.ts
index 7e0069dfe..ad50c5913 100644
--- a/src/cli/tui/screens/generate/defaults.ts
+++ b/src/cli/tui/screens/generate/defaults.ts
@@ -5,7 +5,7 @@ import type { NetworkMode, PythonRuntime } from '../../../../schema';
  */
 
 /** Default Python runtime version for new agents */
-export const DEFAULT_PYTHON_VERSION: PythonRuntime = 'PYTHON_3_12';
+export const DEFAULT_PYTHON_VERSION: PythonRuntime = 'PYTHON_3_13';
 
 /** Default network mode for agent runtimes */
 export const DEFAULT_NETWORK_MODE: NetworkMode = 'PUBLIC';
diff --git a/src/lib/packaging/index.ts b/src/lib/packaging/index.ts
index daa7bb325..58adf9adc 100644
--- a/src/lib/packaging/index.ts
+++ b/src/lib/packaging/index.ts
@@ -78,7 +78,7 @@ export async function packRuntime(spec: AgentEnvSpec, options?: PackageOptions):
  * Defaults to Python if no runtimeVersion is specified.
  */
 export function packCodeZipSync(config: CodeBundleConfig | AgentEnvSpec, options?: PackageOptions): ArtifactResult {
-  const runtimeVersion = config.runtimeVersion ?? 'PYTHON_3_12';
+  const runtimeVersion = config.runtimeVersion ?? 'PYTHON_3_13';
   const packager = getCodeZipPackager(runtimeVersion);
   return packager.packCodeZip(config as AgentEnvSpec, options);
 }
diff --git a/src/lib/packaging/python.ts b/src/lib/packaging/python.ts
index c2efd8dfe..8e508b452 100644
--- a/src/lib/packaging/python.ts
+++ b/src/lib/packaging/python.ts
@@ -155,7 +155,7 @@ export class PythonCodeZipPackager implements RuntimePackager {
  */
 export class PythonCodeZipPackagerSync implements CodeZipPackager {
   packCodeZip(config: AgentEnvSpec, options: PackageOptions = {}): ArtifactResult {
-    const runtimeVersion = config.runtimeVersion ?? 'PYTHON_3_12';
+    const runtimeVersion = config.runtimeVersion ?? 'PYTHON_3_13';
 
     if (!isPythonRuntimeVersion(runtimeVersion)) {
       throw new PackagingError(`Python packager only supports Python runtimes. Received: ${runtimeVersion}`);
diff --git a/src/tui-harness/helpers.ts b/src/tui-harness/helpers.ts
index 5e02fa762..c3e953ab5 100644
--- a/src/tui-harness/helpers.ts
+++ b/src/tui-harness/helpers.ts
@@ -103,7 +103,7 @@ export async function createMinimalProjectDir(
       build: 'CodeZip',
       entrypoint: 'main.py:handler',
       codeLocation: 'app/TestAgent',
-      runtimeVersion: 'PYTHON_3_12',
+      runtimeVersion: 'PYTHON_3_13',
     });
 
     // Create the agent code directory so the CLI does not complain.