diff --git a/e2e/helpers/test-repo.ts b/e2e/helpers/test-repo.ts
index 35cd4f1..e3d4adf 100644
--- a/e2e/helpers/test-repo.ts
+++ b/e2e/helpers/test-repo.ts
@@ -43,6 +43,7 @@ export interface CreateTestRepoOptions {
 function getGitHubUser(): string {
   const user = execFileSync('gh', ['api', 'user', '--jq', '.login'], {
     encoding: 'utf-8',
+    stdio: 'pipe',
   }).trim();
 
   if (!user) {
diff --git a/e2e/specs/config-priority.e2e.ts b/e2e/specs/config-priority.e2e.ts
index 672155f..e782e6b 100644
--- a/e2e/specs/config-priority.e2e.ts
+++ b/e2e/specs/config-priority.e2e.ts
@@ -1,7 +1,8 @@
 import { describe, it, expect, beforeEach, afterEach } from 'vitest';
 import { dirname, join, resolve } from 'node:path';
 import { fileURLToPath } from 'node:url';
-import { mkdirSync, writeFileSync } from 'node:fs';
+import { mkdirSync, readFileSync, writeFileSync } from 'node:fs';
+import { parse as parseYaml } from 'yaml';
 import { createIsolatedEnv, updateIsolatedConfig, type IsolatedEnv } from '../helpers/isolated-env';
 import { createTestRepo, type TestRepo } from '../helpers/test-repo';
 import { runTakt } from '../helpers/takt-runner';
@@ -9,6 +10,17 @@ import { runTakt } from '../helpers/takt-runner';
 const __filename = fileURLToPath(import.meta.url);
 const __dirname = dirname(__filename);
 
+function readFirstTask(repoPath: string): Record<string, unknown> {
+  const tasksPath = join(repoPath, '.takt', 'tasks.yaml');
+  const raw = readFileSync(tasksPath, 'utf-8');
+  const parsed = parseYaml(raw) as { tasks?: Array<Record<string, unknown>> } | null;
+  const first = parsed?.tasks?.[0];
+  if (!first) {
+    throw new Error(`No task record found in ${tasksPath}`);
+  }
+  return first;
+}
+
 // E2E更新時は docs/testing/e2e.md も更新すること
 describe('E2E: Config priority (piece / autoPr)', () => {
   let isolatedEnv: IsolatedEnv;
@@ -67,7 +79,7 @@ describe('E2E: Config priority (piece / autoPr)', () => {
     const piecePath = resolve(__dirname, '../fixtures/pieces/mock-single-step.yaml');
     const scenarioPath = resolve(__dirname, '../fixtures/scenarios/execute-done.json');
 
-    const result = runTakt({
+    runTakt({
       args: [
         '--task', 'Auto PR default behavior',
         '--piece', piecePath,
@@ -82,10 +94,8 @@ describe('E2E: Config priority (piece / autoPr)', () => {
       timeout: 240_000,
     });
 
-    // auto_pr=true の場合は PR 作成フローに入り、テスト環境では gh 未認証のため失敗する
-    const output = result.stdout + result.stderr;
-    expect(result.exitCode).toBe(1);
-    expect(output).toContain('PR creation failed:');
+    const task = readFirstTask(testRepo.path);
+    expect(task['auto_pr']).toBe(true);
   }, 240_000);
 
   it('should use auto_pr from config when set', () => {
@@ -108,9 +118,9 @@ describe('E2E: Config priority (piece / autoPr)', () => {
       timeout: 240_000,
     });
 
-    const output = result.stdout + result.stderr;
     expect(result.exitCode).toBe(0);
-    expect(output).not.toContain('PR creation failed:');
+    const task = readFirstTask(testRepo.path);
+    expect(task['auto_pr']).toBe(false);
   }, 240_000);
 
   it('should prioritize env auto_pr over config', () => {
@@ -118,7 +128,7 @@ describe('E2E: Config priority (piece / autoPr)', () => {
     const scenarioPath = resolve(__dirname, '../fixtures/scenarios/execute-done.json');
     updateIsolatedConfig(isolatedEnv.taktDir, { auto_pr: false });
 
-    const result = runTakt({
+    runTakt({
       args: [
         '--task', 'Auto PR from env override',
         '--piece', piecePath,
@@ -134,9 +144,7 @@ describe('E2E: Config priority (piece / autoPr)', () => {
       timeout: 240_000,
     });
 
-    // env override により auto_pr=true が優先され、PR 作成フローに入る
-    const output = result.stdout + result.stderr;
-    expect(result.exitCode).toBe(1);
-    expect(output).toContain('PR creation failed:');
+    const task = readFirstTask(testRepo.path);
+    expect(task['auto_pr']).toBe(true);
   }, 240_000);
 });
diff --git a/src/__tests__/it-pipeline-modes.test.ts b/src/__tests__/it-pipeline-modes.test.ts
index 1e3a66b..90212d2 100644
--- a/src/__tests__/it-pipeline-modes.test.ts
+++ b/src/__tests__/it-pipeline-modes.test.ts
@@ -115,6 +115,7 @@ vi.mock('../infra/config/global/globalConfig.js', async (importOriginal) => {
     ...original,
     loadGlobalConfig: vi.fn().mockReturnValue({
       language: 'en',
+      provider: 'mock',
       enableBuiltinPieces: true,
       disabledBuiltins: [],
     }),
diff --git a/src/__tests__/it-pipeline.test.ts b/src/__tests__/it-pipeline.test.ts
index 264a879..dc89c24 100644
--- a/src/__tests__/it-pipeline.test.ts
+++ b/src/__tests__/it-pipeline.test.ts
@@ -96,6 +96,7 @@ vi.mock('../infra/config/global/globalConfig.js', async (importOriginal) => {
     ...original,
     loadGlobalConfig: vi.fn().mockReturnValue({
       language: 'en',
+      provider: 'mock',
       enableBuiltinPieces: true,
       disabledBuiltins: [],
     }),
diff --git a/src/__tests__/options-builder.test.ts b/src/__tests__/options-builder.test.ts
index 5f14d37..9acc219 100644
--- a/src/__tests__/options-builder.test.ts
+++ b/src/__tests__/options-builder.test.ts
@@ -57,7 +57,7 @@ describe('OptionsBuilder.buildBaseOptions', () => {
     expect(options.permissionMode).toBe('full');
   });
 
-  it('uses default profile when provider_profiles are not provided', () => {
+  it('uses readonly when provider is not configured', () => {
     const step = createMovement();
     const builder = createBuilder(step, {
       provider: undefined,
@@ -65,7 +65,7 @@ describe('OptionsBuilder.buildBaseOptions', () => {
     });
 
     const options = builder.buildBaseOptions(step);
-    expect(options.permissionMode).toBe('edit');
+    expect(options.permissionMode).toBe('readonly');
   });
 
   it('merges provider options with precedence: global < movement < project', () => {
diff --git a/src/agents/runner.ts b/src/agents/runner.ts
index c62f2c7..1fe6645 100644
--- a/src/agents/runner.ts
+++ b/src/agents/runner.ts
@@ -34,9 +34,12 @@ export class AgentRunner {
       { provider: options?.stepProvider },
       { provider: config.provider },
       { provider: agentConfig?.provider },
-    ]).provider ?? 'claude';
+    ]).provider;
+    if (!resolvedProvider) {
+      throw new Error('No provider configured. Set "provider" in ~/.takt/config.yaml');
+    }
 
-    const configModel = (config.provider ?? 'claude') === resolvedProvider
+    const configModel = config.provider === resolvedProvider
       ? config.model
       : undefined;
     const resolvedModel = resolveProviderModelCandidates([
diff --git a/src/core/piece/engine/OptionsBuilder.ts b/src/core/piece/engine/OptionsBuilder.ts
index 089d70a..8515e19 100644
--- a/src/core/piece/engine/OptionsBuilder.ts
+++ b/src/core/piece/engine/OptionsBuilder.ts
@@ -64,7 +64,7 @@ export class OptionsBuilder {
       model: this.engineOptions.model,
       personaProviders: this.engineOptions.personaProviders,
     });
-    const resolvedProvider = resolved.provider ?? this.engineOptions.provider ?? 'claude';
+    const resolvedProvider = resolved.provider ?? this.engineOptions.provider;
     const resolvedModel = resolved.model ?? this.engineOptions.model;
 
     return {
diff --git a/src/core/piece/permission-profile-resolution.ts b/src/core/piece/permission-profile-resolution.ts
index 340626f..a877aef 100644
--- a/src/core/piece/permission-profile-resolution.ts
+++ b/src/core/piece/permission-profile-resolution.ts
@@ -30,12 +30,7 @@ export const DEFAULT_PROVIDER_PERMISSION_PROFILES: ProviderPermissionProfiles =
  */
 export function resolveMovementPermissionMode(input: ResolvePermissionModeInput): PermissionMode {
   if (!input.provider) {
-    if (input.requiredPermissionMode) {
-      return input.requiredPermissionMode;
-    }
-    throw new Error(
-      `Unable to resolve permission mode for movement "${input.movementName}": provider is required when movement.required_permission_mode is omitted.`,
-    );
+    return input.requiredPermissionMode ?? 'readonly';
   }
 
   const projectProfile = input.projectProviderProfiles?.[input.provider];
diff --git a/src/features/tasks/execute/pieceExecution.ts b/src/features/tasks/execute/pieceExecution.ts
index 59331e9..0e8e888 100644
--- a/src/features/tasks/execute/pieceExecution.ts
+++ b/src/features/tasks/execute/pieceExecution.ts
@@ -340,6 +340,9 @@ export async function executePiece(
   const shouldNotifyPieceComplete = shouldNotify && notificationSoundEvents?.pieceComplete !== false;
   const shouldNotifyPieceAbort = shouldNotify && notificationSoundEvents?.pieceAbort !== false;
   const currentProvider = globalConfig.provider;
+  if (!currentProvider) {
+    throw new Error('No provider configured. Set "provider" in ~/.takt/config.yaml');
+  }
   const effectivePieceConfig: PieceConfig = {
     ...pieceConfig,
     runtime: resolveRuntimeConfig(globalConfig.runtime, pieceConfig.runtime),
@@ -555,7 +558,7 @@ export async function executePiece(
       model: options.model,
       personaProviders: options.personaProviders,
     });
-    const movementProvider = resolved.provider ?? 'claude';
+    const movementProvider = resolved.provider ?? options.provider ?? currentProvider;
     const resolvedModel = resolved.model;
     const movementModel = resolvedModel ?? '(default)';
     currentMovementProvider = movementProvider;
diff --git a/src/features/tasks/list/taskSyncAction.ts b/src/features/tasks/list/taskSyncAction.ts
index 0c0eb0c..4501f03 100644
--- a/src/features/tasks/list/taskSyncAction.ts
+++ b/src/features/tasks/list/taskSyncAction.ts
@@ -70,7 +70,10 @@ export async function syncBranchWithRoot(
   const prompt = loadTemplate('sync_conflict_resolver_message', lang, { originalInstruction });
 
   const config = resolveConfigValues(projectDir, ['provider', 'model']);
-  const providerType = (config.provider ?? 'claude') as ProviderType;
+  if (!config.provider) {
+    throw new Error('No provider configured. Set "provider" in ~/.takt/config.yaml');
+  }
+  const providerType = config.provider as ProviderType;
   const provider = getProvider(providerType);
   const agent = provider.setup({ name: 'conflict-resolver', systemPrompt });
 
diff --git a/src/infra/config/resolveConfigValue.ts b/src/infra/config/resolveConfigValue.ts
index 5125e5c..1b87722 100644
--- a/src/infra/config/resolveConfigValue.ts
+++ b/src/infra/config/resolveConfigValue.ts
@@ -64,7 +64,6 @@ const RESOLUTION_REGISTRY: Partial<{ [K in ConfigParameterKey]: ResolutionRule<K
   piece: { layers: ['local', 'global'], defaultValue: 'default' },
   provider: {
     layers: ['local', 'piece', 'global'],
-    defaultValue: 'claude',
     pieceValue: (pieceContext) => pieceContext?.provider,
   },
   model: {
diff --git a/src/infra/config/resolvedConfig.ts b/src/infra/config/resolvedConfig.ts
index 820dc73..0aecf1c 100644
--- a/src/infra/config/resolvedConfig.ts
+++ b/src/infra/config/resolvedConfig.ts
@@ -1,8 +1,7 @@
 import type { PersistedGlobalConfig } from '../../core/models/persisted-global-config.js';
 
-export interface LoadedConfig extends Omit<PersistedGlobalConfig, 'provider' | 'verbose'> {
+export interface LoadedConfig extends Omit<PersistedGlobalConfig, 'verbose'> {
   piece: string;
-  provider: NonNullable<PersistedGlobalConfig['provider']>;
   verbose: boolean;
 }
 
diff --git a/src/infra/task/summarize.ts b/src/infra/task/summarize.ts
index 17ba84f..47f5a90 100644
--- a/src/infra/task/summarize.ts
+++ b/src/infra/task/summarize.ts
@@ -67,7 +67,10 @@ export class TaskSummarizer {
       log.info('Task name romanized', { original: taskName, slug });
       return slug || 'task';
     }
-    const providerType = (globalConfig.provider as ProviderType) ?? 'claude';
+    if (!globalConfig.provider) {
+      throw new Error('No provider configured. Set "provider" in ~/.takt/config.yaml');
+    }
+    const providerType = globalConfig.provider as ProviderType;
     const model = options.model ?? globalConfig.model;
 
     const provider = getProvider(providerType);