feat: add Bedrock Mantle API format support for harness

src/assets/__tests__/__snapshots__/assets.snapshot.test.ts.snap

@@ -113,6 +113,7 @@ async function main() {
     apiKeyArn?: string;
     efsAccessPoints?: { accessPointArn: string; mountPath: string }[];
     s3AccessPoints?: { accessPointArn: string; mountPath: string }[];
+    apiFormat?: 'converse_stream' | 'responses' | 'chat_completions';
   }[] = [];
   for (const entry of specAny.harnesses ?? []) {
     const harnessDir = path.resolve(projectRoot, entry.path);
@@ -131,6 +132,7 @@ async function main() {
         apiKeyArn: harnessSpec.model?.apiKeyArn,
         efsAccessPoints: harnessSpec.efsAccessPoints,
         s3AccessPoints: harnessSpec.s3AccessPoints,
+        apiFormat: harnessSpec.model?.apiFormat,
       });
     } catch (err) {
       throw new Error(

src/assets/cdk/bin/cdk.ts

@@ -68,6 +68,7 @@ async function main() {
     apiKeyArn?: string;
     efsAccessPoints?: { accessPointArn: string; mountPath: string }[];
     s3AccessPoints?: { accessPointArn: string; mountPath: string }[];
+    apiFormat?: 'converse_stream' | 'responses' | 'chat_completions';
   }[] = [];
   for (const entry of specAny.harnesses ?? []) {
     const harnessDir = path.resolve(projectRoot, entry.path);
@@ -86,6 +87,7 @@ async function main() {
         apiKeyArn: harnessSpec.model?.apiKeyArn,
         efsAccessPoints: harnessSpec.efsAccessPoints,
         s3AccessPoints: harnessSpec.s3AccessPoints,
+        apiFormat: harnessSpec.model?.apiFormat,
       });
     } catch (err) {
       throw new Error(

src/cli/aws/agentcore-harness.ts

@@ -19,6 +19,7 @@ export type HarnessStatus = 'CREATING' | 'READY' | 'UPDATING' | 'DELETING' | 'DE
 
 export interface BedrockModelConfig {
   modelId: string;
+  apiFormat?: 'converse_stream' | 'responses' | 'chat_completions';
   temperature?: number;
   topP?: number;
   maxTokens?: number;
@@ -27,6 +28,7 @@ export interface BedrockModelConfig {
 export interface OpenAiModelConfig {
   modelId: string;
   apiKeyArn?: string;
+  apiFormat?: 'responses' | 'chat_completions';
   temperature?: number;
   topP?: number;
   maxTokens?: number;

src/cli/commands/add/types.ts

@@ -97,6 +97,7 @@ export interface AddHarnessCliOptions {
   name?: string;
   modelProvider?: string;
   modelId?: string;
+  apiFormat?: string;
   apiKeyArn?: string;
   container?: string;
   memory?: boolean;

src/cli/commands/add/validate.ts

@@ -19,6 +19,7 @@ import {
   getSupportedModelProviders,
   isValidKmsKeyArn,
   matchEnumValue,
+  validateApiFormat,
 } from '../../../schema';
 import { ARN_VALIDATION_MESSAGE, isValidArn } from '../shared/arn-utils';
 import { validateHeaderAllowlist } from '../shared/header-utils';
@@ -892,6 +893,14 @@ const VALID_HARNESS_TOOLS = [
 const VALID_GATEWAY_OUTBOUND_AUTH = ['awsIam', 'none', 'oauth'] as const;
 
 export function validateAddHarnessOptions(options: AddHarnessCliOptions): ValidationResult {
+  if (options.apiFormat) {
+    const provider = options.modelProvider ?? 'bedrock';
+    const formatResult = validateApiFormat(options.apiFormat, provider);
+    if (!formatResult.valid) {
+      return { valid: false, error: formatResult.error };
+    }
+  }
+
   if (options.tools) {
     const toolNames = options.tools.split(',').map(s => s.trim());
     for (const tool of toolNames) {

src/cli/commands/create/__tests__/harness-validate.test.ts

@@ -26,6 +26,92 @@ const vpcOptions = {
   securityGroups: 'sg-07234e16e36d51629',
 };
 
+// ─────────────────────────────────────────────────────────────────────────────
+// apiFormat validation
+// ─────────────────────────────────────────────────────────────────────────────
+
+describe('validateCreateHarnessOptions - apiFormat', () => {
+  it('accepts valid apiFormat for bedrock provider', () => {
+    const result = validateCreateHarnessOptions({ ...baseOptions, apiFormat: 'responses' }, makeCwd());
+    expect(result.valid).toBe(true);
+  });
+
+  it('accepts chat_completions format', () => {
+    const result = validateCreateHarnessOptions({ ...baseOptions, apiFormat: 'chat_completions' }, makeCwd());
+    expect(result.valid).toBe(true);
+  });
+
+  it('accepts converse_stream format', () => {
+    const result = validateCreateHarnessOptions({ ...baseOptions, apiFormat: 'converse_stream' }, makeCwd());
+    expect(result.valid).toBe(true);
+  });
+
+  it('rejects invalid apiFormat value', () => {
+    const result = validateCreateHarnessOptions({ ...baseOptions, apiFormat: 'invalid_format' }, makeCwd());
+    expect(result.valid).toBe(false);
+    expect(result.error).toContain('Invalid API format');
+  });
+
+  it('accepts responses format for open_ai provider', () => {
+    const result = validateCreateHarnessOptions(
+      {
+        ...baseOptions,
+        modelProvider: 'open_ai',
+        apiKeyArn: 'arn:aws:secretsmanager:us-east-1:123:secret:key',
+        apiFormat: 'responses',
+      },
+      makeCwd()
+    );
+    expect(result.valid).toBe(true);
+  });
+
+  it('accepts chat_completions format for open_ai provider', () => {
+    const result = validateCreateHarnessOptions(
+      {
+        ...baseOptions,
+        modelProvider: 'open_ai',
+        apiKeyArn: 'arn:aws:secretsmanager:us-east-1:123:secret:key',
+        apiFormat: 'chat_completions',
+      },
+      makeCwd()
+    );
+    expect(result.valid).toBe(true);
+  });
+
+  it('rejects converse_stream for open_ai provider', () => {
+    const result = validateCreateHarnessOptions(
+      {
+        ...baseOptions,
+        modelProvider: 'open_ai',
+        apiKeyArn: 'arn:aws:secretsmanager:us-east-1:123:secret:key',
+        apiFormat: 'converse_stream',
+      },
+      makeCwd()
+    );
+    expect(result.valid).toBe(false);
+    expect(result.error).toContain('Invalid API format for open_ai');
+  });
+
+  it('rejects apiFormat for gemini provider', () => {
+    const result = validateCreateHarnessOptions(
+      {
+        ...baseOptions,
+        modelProvider: 'gemini',
+        apiKeyArn: 'arn:aws:secretsmanager:us-east-1:123:secret:key',
+        apiFormat: 'responses',
+      },
+      makeCwd()
+    );
+    expect(result.valid).toBe(false);
+    expect(result.error).toContain('only supported for bedrock and open_ai');
+  });
+
+  it('passes when apiFormat is not specified', () => {
+    const result = validateCreateHarnessOptions(baseOptions, makeCwd());
+    expect(result.valid).toBe(true);
+  });
+});
+
 // ─────────────────────────────────────────────────────────────────────────────
 // EFS access point validation
 // ─────────────────────────────────────────────────────────────────────────────

src/cli/commands/create/harness-action.ts

@@ -1,5 +1,5 @@
 import { CONFIG_DIR } from '../../../lib';
-import type { HarnessModelProvider, NetworkMode } from '../../../schema';
+import type { HarnessApiFormat, HarnessModelProvider, NetworkMode } from '../../../schema';
 import { harnessPrimitive } from '../../primitives/registry';
 import { type ProgressCallback, createProject } from './action';
 import type { CreateResult } from './types';
@@ -12,6 +12,7 @@ export interface CreateHarnessProjectOptions {
   cwd: string;
   modelProvider: HarnessModelProvider;
   modelId: string;
+  apiFormat?: HarnessApiFormat;
   apiKeyArn?: string;
   skipMemory?: boolean;
   containerUri?: string;
@@ -59,6 +60,7 @@ export async function createProjectWithHarness(options: CreateHarnessProjectOpti
       name: options.name,
       modelProvider: options.modelProvider,
       modelId: options.modelId,
+      apiFormat: options.apiFormat,
       apiKeyArn: options.apiKeyArn,
       containerUri: options.containerUri,
       dockerfilePath: options.dockerfilePath,

src/cli/commands/create/harness-validate.ts

@@ -1,4 +1,4 @@
-import { MAX_EFS_MOUNTS, MAX_S3_MOUNTS } from '../../../schema';
+import { MAX_EFS_MOUNTS, MAX_S3_MOUNTS, validateApiFormat } from '../../../schema';
 import { HarnessNameSchema, ProjectNameSchema } from '../../../schema';
 import {
   validateAccessPointMounts,
@@ -13,6 +13,7 @@
   projectName?: string;
   modelProvider?: string;
   modelId?: string;
+  apiFormat?: string;
   apiKeyArn?: string;
   container?: string;
   noMemory?: boolean;
@@ -102,6 +103,13 @@
     return { valid: false, error: `--api-key-arn is required for ${options.modelProvider} provider` };
   }
 
+  if (options.apiFormat) {
+    const formatResult = validateApiFormat(options.apiFormat, options.modelProvider ?? 'bedrock');
+    if (!formatResult.valid) {
+      return { valid: false, error: formatResult.error };
+    }
+  }
+
   // Validate EFS access point ARN/path pairs
   const efsArns = options.efsAccessPointArn ?? [];
   const efsPaths = options.efsMountPath ?? [];

src/cli/operations/deploy/imperative/deployers/__tests__/harness-mapper.test.ts

@@ -87,6 +87,95 @@ describe('mapHarnessSpecToCreateOptions', () => {
       });
     });
 
+    it('maps bedrock with apiFormat responses', async () => {
+      const opts = baseOptions({
+        harnessSpec: {
+          name: 'h',
+          model: { provider: 'bedrock', modelId: 'openai.gpt-oss-120b', apiFormat: 'responses' },
+          tools: [],
+          skills: [],
+        } as any,
+      });
+      const result = await mapHarnessSpecToCreateOptions(opts);
+      expect(result.model).toEqual({
+        bedrockModelConfig: { modelId: 'openai.gpt-oss-120b', apiFormat: 'responses' },
+      });
+    });
+
+    it('maps bedrock with apiFormat chat_completions', async () => {
+      const opts = baseOptions({
+        harnessSpec: {
+          name: 'h',
+          model: { provider: 'bedrock', modelId: 'openai.gpt-oss-120b', apiFormat: 'chat_completions' },
+          tools: [],
+          skills: [],
+        } as any,
+      });
+      const result = await mapHarnessSpecToCreateOptions(opts);
+      expect(result.model).toEqual({
+        bedrockModelConfig: { modelId: 'openai.gpt-oss-120b', apiFormat: 'chat_completions' },
+      });
+    });
+
+    it('omits apiFormat when converse_stream (default)', async () => {
+      const opts = baseOptions({
+        harnessSpec: {
+          name: 'h',
+          model: { provider: 'bedrock', modelId: 'claude', apiFormat: 'converse_stream' },
+          tools: [],
+          skills: [],
+        } as any,
+      });
+      const result = await mapHarnessSpecToCreateOptions(opts);
+      expect(result.model).toEqual({
+        bedrockModelConfig: { modelId: 'claude' },
+      });
+    });
+
+    it('maps open_ai with apiFormat chat_completions', async () => {
+      const opts = baseOptions({
+        harnessSpec: {
+          name: 'h',
+          model: {
+            provider: 'open_ai',
+            modelId: 'gpt-5',
+            apiKeyArn: 'arn:aws:secretsmanager:us-east-1:123:secret:key',
+            apiFormat: 'chat_completions',
+          },
+          tools: [],
+          skills: [],
+        } as any,
+      });
+      const result = await mapHarnessSpecToCreateOptions(opts);
+      expect(result.model).toEqual({
+        openAiModelConfig: {
+          modelId: 'gpt-5',
+          apiKeyArn: 'arn:aws:secretsmanager:us-east-1:123:secret:key',
+          apiFormat: 'chat_completions',
+        },
+      });
+    });
+
+    it('omits apiFormat for open_ai when responses (default)', async () => {
+      const opts = baseOptions({
+        harnessSpec: {
+          name: 'h',
+          model: {
+            provider: 'open_ai',
+            modelId: 'gpt-5',
+            apiKeyArn: 'arn:aws:secretsmanager:us-east-1:123:secret:key',
+            apiFormat: 'responses',
+          },
+          tools: [],
+          skills: [],
+        } as any,
+      });
+      const result = await mapHarnessSpecToCreateOptions(opts);
+      expect(result.model).toEqual({
+        openAiModelConfig: { modelId: 'gpt-5', apiKeyArn: 'arn:aws:secretsmanager:us-east-1:123:secret:key' },
+      });
+    });
+
     it('includes optional model params when set', async () => {
       const opts = baseOptions({
         harnessSpec: {

src/cli/operations/deploy/imperative/deployers/harness-mapper.ts

@@ -153,13 +153,14 @@ export async function mapHarnessSpecToCreateOptions(options: MapHarnessOptions):
 // ============================================================================
 
 function mapModel(model: HarnessSpec['model']): HarnessModelConfiguration {
-  const { provider, modelId, apiKeyArn, temperature, topP, topK, maxTokens } = model;
+  const { provider, modelId, apiKeyArn, apiFormat, temperature, topP, topK, maxTokens } = model;
 
   switch (provider) {
     case 'bedrock':
       return {
         bedrockModelConfig: {
           modelId,
+          ...(apiFormat && apiFormat !== 'converse_stream' && { apiFormat }),
           ...(temperature !== undefined && { temperature }),
           ...(topP !== undefined && { topP }),
           ...(maxTokens !== undefined && { maxTokens }),
@@ -170,6 +171,7 @@ function mapModel(model: HarnessSpec['model']): HarnessModelConfiguration {
         openAiModelConfig: {
           modelId,
           ...(apiKeyArn && { apiKeyArn }),
+          ...(apiFormat && apiFormat !== 'responses' && { apiFormat: apiFormat as 'responses' | 'chat_completions' }),
           ...(temperature !== undefined && { temperature }),
           ...(topP !== undefined && { topP }),
           ...(maxTokens !== undefined && { maxTokens }),