feat: add customizable AI prompts with enhanced UX

Add comprehensive prompt customization system allowing users to customize all AI prompts (Auto Mode, Agent Runner, Backlog Plan, Enhancement) through the Settings UI. ## Features ### Core Customization System - New TypeScript types for prompt customization with enabled flag - CustomPrompt interface with value and enabled state - Prompts preserved even when disabled (no data loss) - Merged prompt system (custom overrides defaults when enabled) - Persistent storage in ~/.automaker/settings.json ### Settings UI - New "Prompt Customization" section in Settings - 4 tabs: Auto Mode, Agent, Backlog Plan, Enhancement - Toggle-based editing (read-only default → editable custom) - Dynamic textarea height based on prompt length (120px-600px) - Visual state indicators (Custom/Default labels) ### Warning System - Critical prompt warnings for Backlog Plan (JSON format requirement) - Field-level warnings when editing critical prompts - Info banners for Auto Mode planning markers - Color-coded warnings (blue=info, amber=critical) ### Backend Integration - Auto Mode service loads prompts from settings - Agent service loads prompts from settings - Backlog Plan service loads prompts from settings - Enhancement endpoint loads prompts from settings - Settings sync includes promptCustomization field ### Files Changed - libs/types/src/prompts.ts - Type definitions - libs/prompts/src/defaults.ts - Default prompt values - libs/prompts/src/merge.ts - Merge utilities - apps/ui/src/components/views/settings-view/prompts/ - UI components - apps/server/src/lib/settings-helpers.ts - getPromptCustomization() - All service files updated to use customizable prompts ## Technical Details Prompt storage format: ```json { "promptCustomization": { "autoMode": { "planningLite": { "value": "Custom prompt text...", "enabled": true } } } } ``` 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
2026-02-01 08:13:37 +00:00 · 2025-12-29 23:17:20 +01:00
parent 25c9259b50
commit bc0ef47323
20 changed files with 1338 additions and 265 deletions
--- a/apps/server/src/index.ts
+++ b/apps/server/src/index.ts
@@ -155,7 +155,7 @@ app.use('/api/agent', createAgentRoutes(agentService, events));
 app.use('/api/sessions', createSessionsRoutes(agentService));
 app.use('/api/features', createFeaturesRoutes(featureLoader));
 app.use('/api/auto-mode', createAutoModeRoutes(autoModeService));
-app.use('/api/enhance-prompt', createEnhancePromptRoutes());
+app.use('/api/enhance-prompt', createEnhancePromptRoutes(settingsService));
 app.use('/api/worktree', createWorktreeRoutes());
 app.use('/api/git', createGitRoutes());
 app.use('/api/setup', createSetupRoutes());
--- a/apps/server/src/lib/settings-helpers.ts
+++ b/apps/server/src/lib/settings-helpers.ts
@@ -4,7 +4,13 @@

 import type { SettingsService } from '../services/settings-service.js';
 import type { ContextFilesResult, ContextFileInfo } from '@automaker/utils';
-import type { MCPServerConfig, McpServerConfig } from '@automaker/types';
+import type { MCPServerConfig, McpServerConfig, PromptCustomization } from '@automaker/types';
+import {
+  mergeAutoModePrompts,
+  mergeAgentPrompts,
+  mergeBacklogPlanPrompts,
+  mergeEnhancementPrompts,
+} from '@automaker/prompts';

 /**
 * Get the autoLoadClaudeMd setting, with project settings taking precedence over global.
@@ -255,3 +261,43 @@ function convertToSdkFormat(server: MCPServerConfig): McpServerConfig {
    env: server.env,
  };
 }
+
+/**
+ * Get prompt customization from global settings and merge with defaults.
+ * Returns prompts merged with built-in defaults - custom prompts override defaults.
+ *
+ * @param settingsService - Optional settings service instance
+ * @param logPrefix - Prefix for log messages
+ * @returns Promise resolving to merged prompts for all categories
+ */
+export async function getPromptCustomization(
+  settingsService?: SettingsService | null,
+  logPrefix = '[PromptHelper]'
+): Promise<{
+  autoMode: ReturnType<typeof mergeAutoModePrompts>;
+  agent: ReturnType<typeof mergeAgentPrompts>;
+  backlogPlan: ReturnType<typeof mergeBacklogPlanPrompts>;
+  enhancement: ReturnType<typeof mergeEnhancementPrompts>;
+}> {
+  let customization: PromptCustomization = {};
+
+  if (settingsService) {
+    try {
+      const globalSettings = await settingsService.getGlobalSettings();
+      customization = globalSettings.promptCustomization || {};
+      console.log(`${logPrefix} Loaded prompt customization from settings`);
+    } catch (error) {
+      console.error(`${logPrefix} Failed to load prompt customization:`, error);
+      // Fall through to use empty customization (all defaults)
+    }
+  } else {
+    console.log(`${logPrefix} SettingsService not available, using default prompts`);
+  }
+
+  return {
+    autoMode: mergeAutoModePrompts(customization.autoMode),
+    agent: mergeAgentPrompts(customization.agent),
+    backlogPlan: mergeBacklogPlanPrompts(customization.backlogPlan),
+    enhancement: mergeEnhancementPrompts(customization.enhancement),
+  };
+}
--- a/apps/server/src/routes/backlog-plan/generate-plan.ts
+++ b/apps/server/src/routes/backlog-plan/generate-plan.ts
@@ -8,7 +8,7 @@ import { FeatureLoader } from '../../services/feature-loader.js';
 import { ProviderFactory } from '../../providers/provider-factory.js';
 import { logger, setRunningState, getErrorMessage } from './common.js';
 import type { SettingsService } from '../../services/settings-service.js';
-import { getAutoLoadClaudeMdSetting } from '../../lib/settings-helpers.js';
+import { getAutoLoadClaudeMdSetting, getPromptCustomization } from '../../lib/settings-helpers.js';

 const featureLoader = new FeatureLoader();

@@ -79,72 +79,17 @@ export async function generateBacklogPlan(
      content: `Loaded ${features.length} features from backlog`,
    });

+    // Load prompts from settings
+    const prompts = await getPromptCustomization(settingsService, '[BacklogPlan]');
+
    // Build the system prompt
-    const systemPrompt = `You are an AI assistant helping to modify a software project's feature backlog.
-You will be given the current list of features and a user request to modify the backlog.
+    const systemPrompt = prompts.backlogPlan.systemPrompt;

-IMPORTANT CONTEXT (automatically injected):
- Remember to update the dependency graph if deleting existing features
- Remember to define dependencies on new features hooked into relevant existing ones
- Maintain dependency graph integrity (no orphaned dependencies)
- When deleting a feature, identify which other features depend on it
-
-Your task is to analyze the request and produce a structured JSON plan with:
-1. Features to ADD (include title, description, category, and dependencies)
-2. Features to UPDATE (specify featureId and the updates)
-3. Features to DELETE (specify featureId)
-4. A summary of the changes
-5. Any dependency updates needed (removed dependencies due to deletions, new dependencies for new features)
-
-Respond with ONLY a JSON object in this exact format:
-\`\`\`json
-{
-  "changes": [
-    {
-      "type": "add",
-      "feature": {
-        "title": "Feature title",
-        "description": "Feature description",
-        "category": "Category name",
-        "dependencies": ["existing-feature-id"],
-        "priority": 1
-      },
-      "reason": "Why this feature should be added"
-    },
-    {
-      "type": "update",
-      "featureId": "existing-feature-id",
-      "feature": {
-        "title": "Updated title"
-      },
-      "reason": "Why this feature should be updated"
-    },
-    {
-      "type": "delete",
-      "featureId": "feature-id-to-delete",
-      "reason": "Why this feature should be deleted"
-    }
-  ],
-  "summary": "Brief overview of all proposed changes",
-  "dependencyUpdates": [
-    {
-      "featureId": "feature-that-depended-on-deleted",
-      "removedDependencies": ["deleted-feature-id"],
-      "addedDependencies": []
-    }
-  ]
-}
-\`\`\``;
-
-    // Build the user prompt
-    const userPrompt = `Current Features in Backlog:
-${formatFeaturesForPrompt(features)}
-
---
-
-User Request: ${prompt}
-
-Please analyze the current backlog and the user's request, then provide a JSON plan for the modifications.`;
+    // Build the user prompt from template
+    const currentFeatures = formatFeaturesForPrompt(features);
+    const userPrompt = prompts.backlogPlan.userPromptTemplate
+      .replace('{{currentFeatures}}', currentFeatures)
+      .replace('{{userRequest}}', prompt);

    events.emit('backlog-plan:event', {
      type: 'backlog_plan_progress',
--- a/apps/server/src/routes/enhance-prompt/index.ts
+++ b/apps/server/src/routes/enhance-prompt/index.ts
@@ -6,17 +6,19 @@
 */

 import { Router } from 'express';
+import type { SettingsService } from '../../services/settings-service.js';
 import { createEnhanceHandler } from './routes/enhance.js';

 /**
 * Create the enhance-prompt router
 *
+ * @param settingsService - Settings service for loading custom prompts
 * @returns Express router with enhance-prompt endpoints
 */
-export function createEnhancePromptRoutes(): Router {
+export function createEnhancePromptRoutes(settingsService?: SettingsService): Router {
  const router = Router();

-  router.post('/', createEnhanceHandler());
+  router.post('/', createEnhanceHandler(settingsService));

  return router;
 }
--- a/apps/server/src/routes/enhance-prompt/routes/enhance.ts
+++ b/apps/server/src/routes/enhance-prompt/routes/enhance.ts
@@ -10,8 +10,9 @@ import { query } from '@anthropic-ai/claude-agent-sdk';
 import { createLogger } from '@automaker/utils';
 import { resolveModelString } from '@automaker/model-resolver';
 import { CLAUDE_MODEL_MAP } from '@automaker/types';
+import type { SettingsService } from '../../../services/settings-service.js';
+import { getPromptCustomization } from '../../../lib/settings-helpers.js';
 import {
-  getSystemPrompt,
  buildUserPrompt,
  isValidEnhancementMode,
  type EnhancementMode,
@@ -83,9 +84,12 @@ async function extractTextFromStream(
 /**
 * Create the enhance request handler
 *
+ * @param settingsService - Optional settings service for loading custom prompts
 * @returns Express request handler for text enhancement
 */
-export function createEnhanceHandler(): (req: Request, res: Response) => Promise<void> {
+export function createEnhanceHandler(
+  settingsService?: SettingsService
+): (req: Request, res: Response) => Promise<void> {
  return async (req: Request, res: Response): Promise<void> => {
    try {
      const { originalText, enhancementMode, model } = req.body as EnhanceRequestBody;
@@ -128,8 +132,20 @@ export function createEnhanceHandler(): (req: Request, res: Response) => Promise

      logger.info(`Enhancing text with mode: ${validMode}, length: ${trimmedText.length} chars`);

-      // Get the system prompt for this mode
-      const systemPrompt = getSystemPrompt(validMode);
+      // Load enhancement prompts from settings (merges custom + defaults)
+      const prompts = await getPromptCustomization(settingsService, '[EnhancePrompt]');
+
+      // Get the system prompt for this mode from merged prompts
+      const systemPrompt =
+        validMode === 'improve'
+          ? prompts.enhancement.improveSystemPrompt
+          : validMode === 'technical'
+            ? prompts.enhancement.technicalSystemPrompt
+            : validMode === 'simplify'
+              ? prompts.enhancement.simplifySystemPrompt
+              : prompts.enhancement.acceptanceSystemPrompt;
+
+      logger.debug(`Using ${validMode} system prompt (length: ${systemPrompt.length} chars)`);

      // Build the user prompt with few-shot examples
      // This helps the model understand this is text transformation, not a coding task
--- a/apps/server/src/services/agent-service.ts
+++ b/apps/server/src/services/agent-service.ts
@@ -23,6 +23,7 @@ import {
  filterClaudeMdFromContext,
  getMCPServersFromSettings,
  getMCPPermissionSettings,
+  getPromptCustomization,
 } from '../lib/settings-helpers.js';

 interface Message {
@@ -75,6 +76,7 @@ export class AgentService {
  private metadataFile: string;
  private events: EventEmitter;
  private settingsService: SettingsService | null = null;
+  private agentSystemPrompt: string | null = null;

  constructor(dataDir: string, events: EventEmitter, settingsService?: SettingsService) {
    this.stateDir = path.join(dataDir, 'agent-sessions');
@@ -246,7 +248,7 @@ export class AgentService {
      const contextFilesPrompt = filterClaudeMdFromContext(contextResult, autoLoadClaudeMd);

      // Build combined system prompt with base prompt and context files
-      const baseSystemPrompt = this.getSystemPrompt();
+      const baseSystemPrompt = await this.getSystemPrompt();
      const combinedSystemPrompt = contextFilesPrompt
        ? `${contextFilesPrompt}\n\n${baseSystemPrompt}`
        : baseSystemPrompt;
@@ -781,38 +783,13 @@ export class AgentService {
    this.events.emit('agent:stream', { sessionId, ...data });
  }

-  private getSystemPrompt(): string {
-    return `You are an AI assistant helping users build software. You are part of the Automaker application,
-which is designed to help developers plan, design, and implement software projects autonomously.
-
-**Feature Storage:**
-Features are stored in .automaker/features/{id}/feature.json - each feature has its own folder.
-Use the UpdateFeatureStatus tool to manage features, not direct file edits.
-
-Your role is to:
- Help users define their project requirements and specifications
- Ask clarifying questions to better understand their needs
- Suggest technical approaches and architectures
- Guide them through the development process
- Be conversational and helpful
- Write, edit, and modify code files as requested
- Execute commands and tests
- Search and analyze the codebase
-
-When discussing projects, help users think through:
- Core functionality and features
- Technical stack choices
- Data models and architecture
- User experience considerations
- Testing strategies
-
-You have full access to the codebase and can:
- Read files to understand existing code
- Write new files
- Edit existing files
- Run bash commands
- Search for code patterns
- Execute tests and builds`;
+  private async getSystemPrompt(): Promise<string> {
+    // Load from settings if not already cached
+    if (!this.agentSystemPrompt) {
+      const prompts = await getPromptCustomization(this.settingsService, '[AgentService]');
+      this.agentSystemPrompt = prompts.agent.systemPrompt;
+    }
+    return this.agentSystemPrompt;
  }

  private generateId(): string {
--- a/apps/server/src/services/auto-mode-service.ts
+++ b/apps/server/src/services/auto-mode-service.ts
@@ -39,6 +39,7 @@ import {
  filterClaudeMdFromContext,
  getMCPServersFromSettings,
  getMCPPermissionSettings,
+  getPromptCustomization,
 } from '../lib/settings-helpers.js';

 const execAsync = promisify(exec);
@@ -67,162 +68,6 @@ interface PlanSpec {
  tasks?: ParsedTask[];
 }

-const PLANNING_PROMPTS = {
-  lite: `## Planning Phase (Lite Mode)
-
-IMPORTANT: Do NOT output exploration text, tool usage, or thinking before the plan. Start DIRECTLY with the planning outline format below. Silently analyze the codebase first, then output ONLY the structured plan.
-
-Create a brief planning outline:
-
-1. **Goal**: What are we accomplishing? (1 sentence)
-2. **Approach**: How will we do it? (2-3 sentences)
-3. **Files to Touch**: List files and what changes
-4. **Tasks**: Numbered task list (3-7 items)
-5. **Risks**: Any gotchas to watch for
-
-After generating the outline, output:
-"[PLAN_GENERATED] Planning outline complete."
-
-Then proceed with implementation.`,
-
-  lite_with_approval: `## Planning Phase (Lite Mode)
-
-IMPORTANT: Do NOT output exploration text, tool usage, or thinking before the plan. Start DIRECTLY with the planning outline format below. Silently analyze the codebase first, then output ONLY the structured plan.
-
-Create a brief planning outline:
-
-1. **Goal**: What are we accomplishing? (1 sentence)
-2. **Approach**: How will we do it? (2-3 sentences)
-3. **Files to Touch**: List files and what changes
-4. **Tasks**: Numbered task list (3-7 items)
-5. **Risks**: Any gotchas to watch for
-
-After generating the outline, output:
-"[SPEC_GENERATED] Please review the planning outline above. Reply with 'approved' to proceed or provide feedback for revisions."
-
-DO NOT proceed with implementation until you receive explicit approval.`,
-
-  spec: `## Specification Phase (Spec Mode)
-
-IMPORTANT: Do NOT output exploration text, tool usage, or thinking before the spec. Start DIRECTLY with the specification format below. Silently analyze the codebase first, then output ONLY the structured specification.
-
-Generate a specification with an actionable task breakdown. WAIT for approval before implementing.
-
-### Specification Format
-
-1. **Problem**: What problem are we solving? (user perspective)
-
-2. **Solution**: Brief approach (1-2 sentences)
-
-3. **Acceptance Criteria**: 3-5 items in GIVEN-WHEN-THEN format
-   - GIVEN [context], WHEN [action], THEN [outcome]
-
-4. **Files to Modify**:
-   | File | Purpose | Action |
-   |------|---------|--------|
-   | path/to/file | description | create/modify/delete |
-
-5. **Implementation Tasks**:
-   Use this EXACT format for each task (the system will parse these):
-   \`\`\`tasks
-   - [ ] T001: [Description] | File: [path/to/file]
-   - [ ] T002: [Description] | File: [path/to/file]
-   - [ ] T003: [Description] | File: [path/to/file]
-   \`\`\`
-
-   Task ID rules:
-   - Sequential: T001, T002, T003, etc.
-   - Description: Clear action (e.g., "Create user model", "Add API endpoint")
-   - File: Primary file affected (helps with context)
-   - Order by dependencies (foundational tasks first)
-
-6. **Verification**: How to confirm feature works
-
-After generating the spec, output on its own line:
-"[SPEC_GENERATED] Please review the specification above. Reply with 'approved' to proceed or provide feedback for revisions."
-
-DO NOT proceed with implementation until you receive explicit approval.
-
-When approved, execute tasks SEQUENTIALLY in order. For each task:
-1. BEFORE starting, output: "[TASK_START] T###: Description"
-2. Implement the task
-3. AFTER completing, output: "[TASK_COMPLETE] T###: Brief summary"
-
-This allows real-time progress tracking during implementation.`,
-
-  full: `## Full Specification Phase (Full SDD Mode)
-
-IMPORTANT: Do NOT output exploration text, tool usage, or thinking before the spec. Start DIRECTLY with the specification format below. Silently analyze the codebase first, then output ONLY the structured specification.
-
-Generate a comprehensive specification with phased task breakdown. WAIT for approval before implementing.
-
-### Specification Format
-
-1. **Problem Statement**: 2-3 sentences from user perspective
-
-2. **User Story**: As a [user], I want [goal], so that [benefit]
-
-3. **Acceptance Criteria**: Multiple scenarios with GIVEN-WHEN-THEN
-   - **Happy Path**: GIVEN [context], WHEN [action], THEN [expected outcome]
-   - **Edge Cases**: GIVEN [edge condition], WHEN [action], THEN [handling]
-   - **Error Handling**: GIVEN [error condition], WHEN [action], THEN [error response]
-
-4. **Technical Context**:
-   | Aspect | Value |
-   |--------|-------|
-   | Affected Files | list of files |
-   | Dependencies | external libs if any |
-   | Constraints | technical limitations |
-   | Patterns to Follow | existing patterns in codebase |
-
-5. **Non-Goals**: What this feature explicitly does NOT include
-
-6. **Implementation Tasks**:
-   Use this EXACT format for each task (the system will parse these):
-   \`\`\`tasks
-   ## Phase 1: Foundation
-   - [ ] T001: [Description] | File: [path/to/file]
-   - [ ] T002: [Description] | File: [path/to/file]
-
-   ## Phase 2: Core Implementation
-   - [ ] T003: [Description] | File: [path/to/file]
-   - [ ] T004: [Description] | File: [path/to/file]
-
-   ## Phase 3: Integration & Testing
-   - [ ] T005: [Description] | File: [path/to/file]
-   - [ ] T006: [Description] | File: [path/to/file]
-   \`\`\`
-
-   Task ID rules:
-   - Sequential across all phases: T001, T002, T003, etc.
-   - Description: Clear action verb + target
-   - File: Primary file affected
-   - Order by dependencies within each phase
-   - Phase structure helps organize complex work
-
-7. **Success Metrics**: How we know it's done (measurable criteria)
-
-8. **Risks & Mitigations**:
-   | Risk | Mitigation |
-   |------|------------|
-   | description | approach |
-
-After generating the spec, output on its own line:
-"[SPEC_GENERATED] Please review the comprehensive specification above. Reply with 'approved' to proceed or provide feedback for revisions."
-
-DO NOT proceed with implementation until you receive explicit approval.
-
-When approved, execute tasks SEQUENTIALLY by phase. For each task:
-1. BEFORE starting, output: "[TASK_START] T###: Description"
-2. Implement the task
-3. AFTER completing, output: "[TASK_COMPLETE] T###: Brief summary"
-
-After completing all tasks in a phase, output:
-"[PHASE_COMPLETE] Phase N complete"
-
-This allows real-time progress tracking during implementation.`,
-};
-
 /**
 * Parse tasks from generated spec content
 * Looks for the ```tasks code block and extracts task lines
@@ -355,6 +200,7 @@ export class AutoModeService {
  private config: AutoModeConfig | null = null;
  private pendingApprovals = new Map<string, PendingApproval>();
  private settingsService: SettingsService | null = null;
+  private planningPrompts: Record<string, string> | null = null;

  constructor(events: EventEmitter, settingsService?: SettingsService) {
    this.events = events;
@@ -593,7 +439,7 @@ export class AutoModeService {
      } else {
        // Normal flow: build prompt with planning phase
        const featurePrompt = this.buildFeaturePrompt(feature);
-        const planningPrefix = this.getPlanningPromptPrefix(feature);
+        const planningPrefix = await this.getPlanningPromptPrefix(feature);
        prompt = planningPrefix + featurePrompt;

        // Emit planning mode info
@@ -1756,23 +1602,43 @@ Format your response as a structured markdown document.`;
    return firstLine.substring(0, 57) + '...';
  }

+  /**
+   * Load planning prompts from settings
+   */
+  private async loadPlanningPrompts(): Promise<void> {
+    if (this.planningPrompts) {
+      return; // Already loaded
+    }
+
+    const prompts = await getPromptCustomization(this.settingsService, '[AutoMode]');
+    this.planningPrompts = {
+      lite: prompts.autoMode.planningLite,
+      lite_with_approval: prompts.autoMode.planningLiteWithApproval,
+      spec: prompts.autoMode.planningSpec,
+      full: prompts.autoMode.planningFull,
+    };
+  }
+
  /**
   * Get the planning prompt prefix based on feature's planning mode
   */
-  private getPlanningPromptPrefix(feature: Feature): string {
+  private async getPlanningPromptPrefix(feature: Feature): Promise<string> {
    const mode = feature.planningMode || 'skip';

    if (mode === 'skip') {
      return ''; // No planning phase
    }

+    // Load prompts if not already loaded
+    await this.loadPlanningPrompts();
+
    // For lite mode, use the approval variant if requirePlanApproval is true
    let promptKey: string = mode;
    if (mode === 'lite' && feature.requirePlanApproval === true) {
      promptKey = 'lite_with_approval';
    }

-    const planningPrompt = PLANNING_PROMPTS[promptKey as keyof typeof PLANNING_PROMPTS];
+    const planningPrompt = this.planningPrompts![promptKey];
    if (!planningPrompt) {
      return '';
    }
--- a/apps/ui/src/components/views/settings-view.tsx
+++ b/apps/ui/src/components/views/settings-view.tsx
@@ -19,6 +19,7 @@ import { KeyboardShortcutsSection } from './settings-view/keyboard-shortcuts/key
 import { FeatureDefaultsSection } from './settings-view/feature-defaults/feature-defaults-section';
 import { DangerZoneSection } from './settings-view/danger-zone/danger-zone-section';
 import { MCPServersSection } from './settings-view/mcp-servers';
+import { PromptCustomizationSection } from './settings-view/prompts';
 import type { Project as SettingsProject, Theme } from './settings-view/shared/types';
 import type { Project as ElectronProject } from '@/lib/electron';

@@ -53,6 +54,8 @@ export function SettingsView() {
    setAutoLoadClaudeMd,
    enableSandboxMode,
    setEnableSandboxMode,
+    promptCustomization,
+    setPromptCustomization,
  } = useAppStore();

  // Hide usage tracking when using API key (only show for Claude Code CLI users)
@@ -119,6 +122,13 @@ export function SettingsView() {
        );
      case 'mcp-servers':
        return <MCPServersSection />;
+      case 'prompts':
+        return (
+          <PromptCustomizationSection
+            promptCustomization={promptCustomization}
+            onPromptCustomizationChange={setPromptCustomization}
+          />
+        );
      case 'ai-enhancement':
        return <AIEnhancementSection />;
      case 'appearance':
--- a/apps/ui/src/components/views/settings-view/config/navigation.ts
+++ b/apps/ui/src/components/views/settings-view/config/navigation.ts
@@ -10,6 +10,7 @@ import {
  Trash2,
  Sparkles,
  Plug,
+  MessageSquareText,
 } from 'lucide-react';
 import type { SettingsViewId } from '../hooks/use-settings-view';

@@ -24,6 +25,7 @@ export const NAV_ITEMS: NavigationItem[] = [
  { id: 'api-keys', label: 'API Keys', icon: Key },
  { id: 'claude', label: 'Claude', icon: Terminal },
  { id: 'mcp-servers', label: 'MCP Servers', icon: Plug },
+  { id: 'prompts', label: 'Prompt Customization', icon: MessageSquareText },
  { id: 'ai-enhancement', label: 'AI Enhancement', icon: Sparkles },
  { id: 'appearance', label: 'Appearance', icon: Palette },
  { id: 'terminal', label: 'Terminal', icon: SquareTerminal },
--- a/apps/ui/src/components/views/settings-view/hooks/use-settings-view.ts
+++ b/apps/ui/src/components/views/settings-view/hooks/use-settings-view.ts
@@ -4,6 +4,7 @@ export type SettingsViewId =
  | 'api-keys'
  | 'claude'
  | 'mcp-servers'
+  | 'prompts'
  | 'ai-enhancement'
  | 'appearance'
  | 'terminal'
--- a/apps/ui/src/components/views/settings-view/prompts/index.ts
+++ b/apps/ui/src/components/views/settings-view/prompts/index.ts
@@ -0,0 +1 @@
+export { PromptCustomizationSection } from './prompt-customization-section';
--- a/apps/ui/src/components/views/settings-view/prompts/prompt-customization-section.tsx
+++ b/apps/ui/src/components/views/settings-view/prompts/prompt-customization-section.tsx
@@ -0,0 +1,445 @@
+import { useState } from 'react';
+import { Label } from '@/components/ui/label';
+import { Textarea } from '@/components/ui/textarea';
+import { Button } from '@/components/ui/button';
+import { Switch } from '@/components/ui/switch';
+import { Tabs, TabsContent, TabsList, TabsTrigger } from '@/components/ui/tabs';
+import {
+  MessageSquareText,
+  Bot,
+  KanbanSquare,
+  Sparkles,
+  RotateCcw,
+  Info,
+  AlertTriangle,
+} from 'lucide-react';
+import { cn } from '@/lib/utils';
+import type { PromptCustomization, CustomPrompt } from '@automaker/types';
+import {
+  DEFAULT_AUTO_MODE_PROMPTS,
+  DEFAULT_AGENT_PROMPTS,
+  DEFAULT_BACKLOG_PLAN_PROMPTS,
+  DEFAULT_ENHANCEMENT_PROMPTS,
+} from '@automaker/prompts';
+
+interface PromptCustomizationSectionProps {
+  promptCustomization?: PromptCustomization;
+  onPromptCustomizationChange: (customization: PromptCustomization) => void;
+}
+
+interface PromptFieldProps {
+  label: string;
+  description: string;
+  defaultValue: string;
+  customValue?: CustomPrompt;
+  onCustomValueChange: (value: CustomPrompt | undefined) => void;
+  critical?: boolean; // Whether this prompt requires strict output format
+}
+
+/**
+ * Calculate dynamic minimum height based on content length
+ * Ensures long prompts have adequate space
+ */
+function calculateMinHeight(text: string): string {
+  const lines = text.split('\n').length;
+  const estimatedLines = Math.max(lines, Math.ceil(text.length / 80));
+
+  // Min 120px, scales up for longer content, max 600px
+  const minHeight = Math.min(Math.max(120, estimatedLines * 20), 600);
+  return `${minHeight}px`;
+}
+
+/**
+ * PromptField Component
+ *
+ * Shows a prompt with a toggle to switch between default and custom mode.
+ * - Toggle OFF: Shows default prompt in read-only mode, custom value is preserved but not used
+ * - Toggle ON: Allows editing, custom value is used instead of default
+ *
+ * IMPORTANT: Custom value is ALWAYS preserved, even when toggle is OFF.
+ * This prevents users from losing their work when temporarily switching to default.
+ */
+function PromptField({
+  label,
+  description,
+  defaultValue,
+  customValue,
+  onCustomValueChange,
+  critical = false,
+}: PromptFieldProps) {
+  const isEnabled = customValue?.enabled ?? false;
+  const displayValue = isEnabled ? (customValue?.value ?? defaultValue) : defaultValue;
+  const minHeight = calculateMinHeight(displayValue);
+
+  const handleToggle = (enabled: boolean) => {
+    if (enabled) {
+      // Enable custom mode - preserve existing custom value or initialize with default
+      const value = customValue?.value ?? defaultValue;
+      onCustomValueChange({ value, enabled: true });
+    } else {
+      // Disable custom mode - preserve custom value but mark as disabled
+      const value = customValue?.value ?? defaultValue;
+      onCustomValueChange({ value, enabled: false });
+    }
+  };
+
+  const handleTextChange = (newValue: string) => {
+    // Only allow editing when enabled
+    if (isEnabled) {
+      onCustomValueChange({ value: newValue, enabled: true });
+    }
+  };
+
+  return (
+    <div className="space-y-2">
+      {critical && isEnabled && (
+        <div className="flex items-start gap-2 p-3 rounded-lg bg-amber-500/10 border border-amber-500/20">
+          <AlertTriangle className="w-4 h-4 text-amber-500 mt-0.5 flex-shrink-0" />
+          <div className="flex-1">
+            <p className="text-xs font-medium text-amber-500">Critical Prompt</p>
+            <p className="text-xs text-muted-foreground mt-1">
+              This prompt requires a specific output format. Changing it incorrectly may break
+              functionality. Only modify if you understand the expected structure.
+            </p>
+          </div>
+        </div>
+      )}
+      <div className="flex items-center justify-between">
+        <Label htmlFor={label} className="text-sm font-medium">
+          {label}
+        </Label>
+        <div className="flex items-center gap-2">
+          <span className="text-xs text-muted-foreground">{isEnabled ? 'Custom' : 'Default'}</span>
+          <Switch
+            checked={isEnabled}
+            onCheckedChange={handleToggle}
+            className="data-[state=checked]:bg-brand-500"
+          />
+        </div>
+      </div>
+      <Textarea
+        id={label}
+        value={displayValue}
+        onChange={(e) => handleTextChange(e.target.value)}
+        readOnly={!isEnabled}
+        style={{ minHeight }}
+        className={cn(
+          'font-mono text-xs resize-y',
+          !isEnabled && 'cursor-not-allowed bg-muted/50 text-muted-foreground'
+        )}
+      />
+      <p className="text-xs text-muted-foreground">{description}</p>
+    </div>
+  );
+}
+
+/**
+ * PromptCustomizationSection Component
+ *
+ * Allows users to customize AI prompts for different parts of the application:
+ * - Auto Mode (feature implementation)
+ * - Agent Runner (interactive chat)
+ * - Backlog Plan (Kanban planning)
+ * - Enhancement (feature description improvement)
+ */
+export function PromptCustomizationSection({
+  promptCustomization = {},
+  onPromptCustomizationChange,
+}: PromptCustomizationSectionProps) {
+  const [activeTab, setActiveTab] = useState('auto-mode');
+
+  const updatePrompt = (
+    category: keyof PromptCustomization,
+    field: string,
+    value: CustomPrompt | undefined
+  ) => {
+    const updated = {
+      ...promptCustomization,
+      [category]: {
+        ...promptCustomization[category],
+        [field]: value,
+      },
+    };
+    onPromptCustomizationChange(updated);
+  };
+
+  const resetToDefaults = (category: keyof PromptCustomization) => {
+    const updated = {
+      ...promptCustomization,
+      [category]: {},
+    };
+    onPromptCustomizationChange(updated);
+  };
+
+  const resetAllToDefaults = () => {
+    onPromptCustomizationChange({});
+  };
+
+  return (
+    <div
+      className={cn(
+        'rounded-2xl overflow-hidden',
+        'border border-border/50',
+        'bg-gradient-to-br from-card/90 via-card/70 to-card/80 backdrop-blur-xl',
+        'shadow-sm shadow-black/5'
+      )}
+      data-testid="prompt-customization-section"
+    >
+      {/* Header */}
+      <div className="p-6 border-b border-border/50 bg-gradient-to-r from-transparent via-accent/5 to-transparent">
+        <div className="flex items-center justify-between mb-2">
+          <div className="flex items-center gap-3">
+            <div className="w-9 h-9 rounded-xl bg-gradient-to-br from-brand-500/20 to-brand-600/10 flex items-center justify-center border border-brand-500/20">
+              <MessageSquareText className="w-5 h-5 text-brand-500" />
+            </div>
+            <h2 className="text-lg font-semibold text-foreground tracking-tight">
+              Prompt Customization
+            </h2>
+          </div>
+          <Button variant="outline" size="sm" onClick={resetAllToDefaults} className="gap-2">
+            <RotateCcw className="w-4 h-4" />
+            Reset All to Defaults
+          </Button>
+        </div>
+        <p className="text-sm text-muted-foreground/80 ml-12">
+          Customize AI prompts for Auto Mode, Agent Runner, and other features.
+        </p>
+      </div>
+
+      {/* Info Banner */}
+      <div className="px-6 pt-6">
+        <div className="flex items-start gap-3 p-4 rounded-xl bg-blue-500/10 border border-blue-500/20">
+          <Info className="w-5 h-5 text-blue-500 mt-0.5 flex-shrink-0" />
+          <div className="space-y-1">
+            <p className="text-sm text-foreground font-medium">How to Customize Prompts</p>
+            <p className="text-xs text-muted-foreground/80 leading-relaxed">
+              Toggle the switch to enable custom mode and edit the prompt. When disabled, the
+              default built-in prompt is used. You can use the default as a starting point by
+              enabling the toggle.
+            </p>
+          </div>
+        </div>
+      </div>
+
+      {/* Tabs */}
+      <div className="p-6">
+        <Tabs value={activeTab} onValueChange={setActiveTab}>
+          <TabsList className="grid grid-cols-4 w-full">
+            <TabsTrigger value="auto-mode" className="gap-2">
+              <Bot className="w-4 h-4" />
+              Auto Mode
+            </TabsTrigger>
+            <TabsTrigger value="agent" className="gap-2">
+              <MessageSquareText className="w-4 h-4" />
+              Agent
+            </TabsTrigger>
+            <TabsTrigger value="backlog-plan" className="gap-2">
+              <KanbanSquare className="w-4 h-4" />
+              Backlog Plan
+            </TabsTrigger>
+            <TabsTrigger value="enhancement" className="gap-2">
+              <Sparkles className="w-4 h-4" />
+              Enhancement
+            </TabsTrigger>
+          </TabsList>
+
+          {/* Auto Mode Tab */}
+          <TabsContent value="auto-mode" className="space-y-6 mt-6">
+            <div className="flex items-center justify-between mb-4">
+              <h3 className="text-sm font-medium text-foreground">Auto Mode Prompts</h3>
+              <Button
+                variant="ghost"
+                size="sm"
+                onClick={() => resetToDefaults('autoMode')}
+                className="gap-2"
+              >
+                <RotateCcw className="w-3 h-3" />
+                Reset Section
+              </Button>
+            </div>
+
+            {/* Info Banner for Auto Mode */}
+            <div className="flex items-start gap-3 p-4 rounded-xl bg-blue-500/10 border border-blue-500/20">
+              <Info className="w-5 h-5 text-blue-500 mt-0.5 flex-shrink-0" />
+              <div className="space-y-1">
+                <p className="text-sm text-foreground font-medium">Planning Mode Markers</p>
+                <p className="text-xs text-muted-foreground/80 leading-relaxed">
+                  Planning prompts use special markers like{' '}
+                  <code className="px-1 py-0.5 rounded bg-muted text-xs">[PLAN_GENERATED]</code> and{' '}
+                  <code className="px-1 py-0.5 rounded bg-muted text-xs">[SPEC_GENERATED]</code> to
+                  control the Auto Mode workflow. These markers must be preserved for proper
+                  functionality.
+                </p>
+              </div>
+            </div>
+
+            <div className="space-y-4">
+              <PromptField
+                label="Planning: Lite Mode"
+                description="Quick planning outline without approval requirement"
+                defaultValue={DEFAULT_AUTO_MODE_PROMPTS.planningLite}
+                customValue={promptCustomization?.autoMode?.planningLite}
+                onCustomValueChange={(value) => updatePrompt('autoMode', 'planningLite', value)}
+                critical={true}
+              />
+
+              <PromptField
+                label="Planning: Lite with Approval"
+                description="Planning outline that waits for user approval"
+                defaultValue={DEFAULT_AUTO_MODE_PROMPTS.planningLiteWithApproval}
+                customValue={promptCustomization?.autoMode?.planningLiteWithApproval}
+                onCustomValueChange={(value) =>
+                  updatePrompt('autoMode', 'planningLiteWithApproval', value)
+                }
+                critical={true}
+              />
+
+              <PromptField
+                label="Planning: Spec Mode"
+                description="Detailed specification with task breakdown"
+                defaultValue={DEFAULT_AUTO_MODE_PROMPTS.planningSpec}
+                customValue={promptCustomization?.autoMode?.planningSpec}
+                onCustomValueChange={(value) => updatePrompt('autoMode', 'planningSpec', value)}
+                critical={true}
+              />
+
+              <PromptField
+                label="Planning: Full SDD Mode"
+                description="Comprehensive Software Design Document with phased implementation"
+                defaultValue={DEFAULT_AUTO_MODE_PROMPTS.planningFull}
+                customValue={promptCustomization?.autoMode?.planningFull}
+                onCustomValueChange={(value) => updatePrompt('autoMode', 'planningFull', value)}
+                critical={true}
+              />
+            </div>
+          </TabsContent>
+
+          {/* Agent Tab */}
+          <TabsContent value="agent" className="space-y-6 mt-6">
+            <div className="flex items-center justify-between mb-4">
+              <h3 className="text-sm font-medium text-foreground">Agent Runner Prompts</h3>
+              <Button
+                variant="ghost"
+                size="sm"
+                onClick={() => resetToDefaults('agent')}
+                className="gap-2"
+              >
+                <RotateCcw className="w-3 h-3" />
+                Reset Section
+              </Button>
+            </div>
+
+            <div className="space-y-4">
+              <PromptField
+                label="System Prompt"
+                description="Defines the AI's role and behavior in interactive chat sessions"
+                defaultValue={DEFAULT_AGENT_PROMPTS.systemPrompt}
+                customValue={promptCustomization?.agent?.systemPrompt}
+                onCustomValueChange={(value) => updatePrompt('agent', 'systemPrompt', value)}
+              />
+            </div>
+          </TabsContent>
+
+          {/* Backlog Plan Tab */}
+          <TabsContent value="backlog-plan" className="space-y-6 mt-6">
+            <div className="flex items-center justify-between mb-4">
+              <h3 className="text-sm font-medium text-foreground">Backlog Planning Prompts</h3>
+              <Button
+                variant="ghost"
+                size="sm"
+                onClick={() => resetToDefaults('backlogPlan')}
+                className="gap-2"
+              >
+                <RotateCcw className="w-3 h-3" />
+                Reset Section
+              </Button>
+            </div>
+
+            {/* Critical Warning for Backlog Plan */}
+            <div className="flex items-start gap-3 p-4 rounded-xl bg-amber-500/10 border border-amber-500/20">
+              <AlertTriangle className="w-5 h-5 text-amber-500 mt-0.5 flex-shrink-0" />
+              <div className="space-y-1">
+                <p className="text-sm text-foreground font-medium">Warning: Critical Prompts</p>
+                <p className="text-xs text-muted-foreground/80 leading-relaxed">
+                  Backlog plan prompts require a strict JSON output format. Modifying these prompts
+                  incorrectly can break the backlog planning feature and potentially corrupt your
+                  feature data. Only customize if you fully understand the expected output
+                  structure.
+                </p>
+              </div>
+            </div>
+
+            <div className="space-y-4">
+              <PromptField
+                label="System Prompt"
+                description="Defines how the AI modifies the feature backlog (Plan button on Kanban board)"
+                defaultValue={DEFAULT_BACKLOG_PLAN_PROMPTS.systemPrompt}
+                customValue={promptCustomization?.backlogPlan?.systemPrompt}
+                onCustomValueChange={(value) => updatePrompt('backlogPlan', 'systemPrompt', value)}
+                critical={true}
+              />
+            </div>
+          </TabsContent>
+
+          {/* Enhancement Tab */}
+          <TabsContent value="enhancement" className="space-y-6 mt-6">
+            <div className="flex items-center justify-between mb-4">
+              <h3 className="text-sm font-medium text-foreground">Enhancement Prompts</h3>
+              <Button
+                variant="ghost"
+                size="sm"
+                onClick={() => resetToDefaults('enhancement')}
+                className="gap-2"
+              >
+                <RotateCcw className="w-3 h-3" />
+                Reset Section
+              </Button>
+            </div>
+
+            <div className="space-y-4">
+              <PromptField
+                label="Improve Mode"
+                description="Transform vague requests into clear, actionable tasks"
+                defaultValue={DEFAULT_ENHANCEMENT_PROMPTS.improveSystemPrompt}
+                customValue={promptCustomization?.enhancement?.improveSystemPrompt}
+                onCustomValueChange={(value) =>
+                  updatePrompt('enhancement', 'improveSystemPrompt', value)
+                }
+              />
+
+              <PromptField
+                label="Technical Mode"
+                description="Add implementation details and technical specifications"
+                defaultValue={DEFAULT_ENHANCEMENT_PROMPTS.technicalSystemPrompt}
+                customValue={promptCustomization?.enhancement?.technicalSystemPrompt}
+                onCustomValueChange={(value) =>
+                  updatePrompt('enhancement', 'technicalSystemPrompt', value)
+                }
+              />
+
+              <PromptField
+                label="Simplify Mode"
+                description="Make verbose descriptions concise and focused"
+                defaultValue={DEFAULT_ENHANCEMENT_PROMPTS.simplifySystemPrompt}
+                customValue={promptCustomization?.enhancement?.simplifySystemPrompt}
+                onCustomValueChange={(value) =>
+                  updatePrompt('enhancement', 'simplifySystemPrompt', value)
+                }
+              />
+
+              <PromptField
+                label="Acceptance Criteria Mode"
+                description="Add testable acceptance criteria to descriptions"
+                defaultValue={DEFAULT_ENHANCEMENT_PROMPTS.acceptanceSystemPrompt}
+                customValue={promptCustomization?.enhancement?.acceptanceSystemPrompt}
+                onCustomValueChange={(value) =>
+                  updatePrompt('enhancement', 'acceptanceSystemPrompt', value)
+                }
+              />
+            </div>
+          </TabsContent>
+        </Tabs>
+      </div>
+    </div>
+  );
+}
--- a/apps/ui/src/hooks/use-settings-migration.ts
+++ b/apps/ui/src/hooks/use-settings-migration.ts
@@ -231,6 +231,7 @@ export async function syncSettingsToServer(): Promise<boolean> {
      mcpServers: state.mcpServers,
      mcpAutoApproveTools: state.mcpAutoApproveTools,
      mcpUnrestrictedTools: state.mcpUnrestrictedTools,
+      promptCustomization: state.promptCustomization,
      projects: state.projects,
      trashedProjects: state.trashedProjects,
      projectHistory: state.projectHistory,
--- a/apps/ui/src/store/app-store.ts
+++ b/apps/ui/src/store/app-store.ts
@@ -11,6 +11,7 @@ import type {
  FeatureStatusWithPipeline,
  PipelineConfig,
  PipelineStep,
+  PromptCustomization,
 } from '@automaker/types';

 // Re-export ThemeMode for convenience
@@ -492,6 +493,9 @@ export interface AppState {
  mcpAutoApproveTools: boolean; // Auto-approve MCP tool calls without permission prompts
  mcpUnrestrictedTools: boolean; // Allow unrestricted tools when MCP servers are enabled

+  // Prompt Customization
+  promptCustomization: PromptCustomization; // Custom prompts for Auto Mode, Agent, Backlog Plan, Enhancement
+
  // Project Analysis
  projectAnalysis: ProjectAnalysis | null;
  isAnalyzing: boolean;
@@ -774,6 +778,9 @@ export interface AppActions {
  setMcpAutoApproveTools: (enabled: boolean) => Promise<void>;
  setMcpUnrestrictedTools: (enabled: boolean) => Promise<void>;

+  // Prompt Customization actions
+  setPromptCustomization: (customization: PromptCustomization) => Promise<void>;
+
  // AI Profile actions
  addAIProfile: (profile: Omit<AIProfile, 'id'>) => void;
  updateAIProfile: (id: string, updates: Partial<AIProfile>) => void;
@@ -972,6 +979,7 @@ const initialState: AppState = {
  mcpServers: [], // No MCP servers configured by default
  mcpAutoApproveTools: true, // Default to enabled - bypass permission prompts for MCP tools
  mcpUnrestrictedTools: true, // Default to enabled - don't filter allowedTools when MCP enabled
+  promptCustomization: {}, // Empty by default - all prompts use built-in defaults
  aiProfiles: DEFAULT_AI_PROFILES,
  projectAnalysis: null,
  isAnalyzing: false,
@@ -1628,6 +1636,14 @@ export const useAppStore = create<AppState & AppActions>()(
        await syncSettingsToServer();
      },

+      // Prompt Customization actions
+      setPromptCustomization: async (customization) => {
+        set({ promptCustomization: customization });
+        // Sync to server settings file
+        const { syncSettingsToServer } = await import('@/hooks/use-settings-migration');
+        await syncSettingsToServer();
+      },
+
      // AI Profile actions
      addAIProfile: (profile) => {
        const id = `profile-${Date.now()}-${Math.random().toString(36).substr(2, 9)}`;
@@ -2909,6 +2925,8 @@ export const useAppStore = create<AppState & AppActions>()(
          mcpServers: state.mcpServers,
          mcpAutoApproveTools: state.mcpAutoApproveTools,
          mcpUnrestrictedTools: state.mcpUnrestrictedTools,
+          // Prompt customization
+          promptCustomization: state.promptCustomization,
          // Profiles and sessions
          aiProfiles: state.aiProfiles,
          chatSessions: state.chatSessions,
--- a/libs/prompts/src/defaults.ts
+++ b/libs/prompts/src/defaults.ts
@@ -0,0 +1,403 @@
+/**
+ * Default Prompts Library
+ *
+ * Central repository for all default AI prompts used throughout the application.
+ * These prompts can be overridden by user customization in settings.
+ *
+ * Extracted from:
+ * - apps/server/src/services/auto-mode-service.ts (Auto Mode planning prompts)
+ * - apps/server/src/services/agent-service.ts (Agent Runner system prompt)
+ * - apps/server/src/routes/backlog-plan/generate-plan.ts (Backlog planning prompts)
+ */
+
+import type {
+  ResolvedAutoModePrompts,
+  ResolvedAgentPrompts,
+  ResolvedBacklogPlanPrompts,
+  ResolvedEnhancementPrompts,
+} from '@automaker/types';
+
+/**
+ * ========================================================================
+ * AUTO MODE PROMPTS
+ * ========================================================================
+ */
+
+export const DEFAULT_AUTO_MODE_PLANNING_LITE = `## Planning Phase (Lite Mode)
+
+IMPORTANT: Do NOT output exploration text, tool usage, or thinking before the plan. Start DIRECTLY with the planning outline format below.
+
+Create a brief planning outline:
+
+1. **Goal**: What are we accomplishing? (1 sentence)
+2. **Approach**: How will we do it? (2-3 sentences)
+3. **Files to Touch**: List files and what changes
+4. **Tasks**: Numbered task list (3-7 items)
+5. **Risks**: Any gotchas to watch for
+
+After generating the outline, output:
+"[PLAN_GENERATED] Planning outline complete."
+
+Then proceed with implementation.
+`;
+
+export const DEFAULT_AUTO_MODE_PLANNING_LITE_WITH_APPROVAL = `## Planning Phase (Lite Mode with Approval)
+
+IMPORTANT: Do NOT output exploration text, tool usage, or thinking before the plan. Start DIRECTLY with the planning outline format below.
+
+Create a brief planning outline:
+
+1. **Goal**: What are we accomplishing? (1 sentence)
+2. **Approach**: How will we do it? (2-3 sentences)
+3. **Files to Touch**: List files and what changes
+4. **Tasks**: Numbered task list (3-7 items)
+5. **Risks**: Any gotchas to watch for
+
+After generating the outline, output:
+"[SPEC_GENERATED] Please review the plan above. Reply with 'approved' to proceed or provide feedback for revisions."
+
+DO NOT proceed with implementation until approval is received.
+`;
+
+export const DEFAULT_AUTO_MODE_PLANNING_SPEC = `## Specification Phase (Spec Mode)
+
+Generate a specification with an actionable task breakdown. WAIT for approval before implementing.
+
+### Specification Format
+
+1. **Problem**: What problem are we solving? (user perspective)
+2. **Solution**: Brief approach (1-2 sentences)
+3. **Acceptance Criteria**: 3-5 items in GIVEN-WHEN-THEN format
+4. **Files to Modify**:
+   | File | Changes |
+   |------|---------|
+   | path/to/file | Brief description |
+
+5. **Implementation Tasks**:
+   \`\`\`tasks
+   - [ ] T001: [Description] | File: [path/to/file]
+   - [ ] T002: [Description] | File: [path/to/file]
+   - [ ] T003: [Description] | File: [path/to/file]
+   \`\`\`
+
+6. **Verification**: How to confirm feature works
+
+After generating the spec, output:
+"[SPEC_GENERATED] Please review the specification above. Reply with 'approved' to proceed or provide feedback for revisions."
+
+DO NOT proceed with implementation until approval is received.
+`;
+
+export const DEFAULT_AUTO_MODE_PLANNING_FULL = `## Software Design Document (Full Mode)
+
+Generate a comprehensive specification with phased task breakdown. WAIT for approval before implementing.
+
+### SDD Format
+
+#### 1. Problem Statement
+Brief description of the problem we're solving (user perspective)
+
+#### 2. User Story
+AS A [user type]
+I WANT TO [action]
+SO THAT [benefit]
+
+#### 3. Acceptance Criteria
+Multiple scenarios in GIVEN-WHEN-THEN format:
+- **Scenario 1**: [Name]
+  - GIVEN [context]
+  - WHEN [action]
+  - THEN [expected outcome]
+
+#### 4. Technical Context
+- **Existing Components**: What's already in place
+- **Integration Points**: Where this feature connects
+- **Constraints**: Technical or business limitations
+
+#### 5. Non-Goals
+What this feature explicitly does NOT include (to prevent scope creep)
+
+#### 6. Implementation Plan
+
+**Phase 1: Foundation**
+\`\`\`tasks
+- [ ] T001: [Description] | File: [path]
+- [ ] T002: [Description] | File: [path]
+\`\`\`
+
+**Phase 2: Core Implementation**
+\`\`\`tasks
+- [ ] T003: [Description] | File: [path]
+- [ ] T004: [Description] | File: [path]
+\`\`\`
+
+**Phase 3: Integration & Testing**
+\`\`\`tasks
+- [ ] T005: [Description] | File: [path]
+- [ ] T006: [Description] | File: [path]
+\`\`\`
+
+#### 7. Success Metrics
+How we'll measure if this feature is working correctly
+
+#### 8. Risks & Mitigations
+| Risk | Impact | Mitigation |
+|------|--------|------------|
+| [risk] | [H/M/L] | [approach] |
+
+After generating the SDD, output:
+"[SPEC_GENERATED] Please review the specification above. Reply with 'approved' to proceed or provide feedback for revisions."
+
+DO NOT proceed with implementation until approval is received.
+`;
+
+export const DEFAULT_AUTO_MODE_FEATURE_PROMPT_TEMPLATE = `## Feature Implementation Task
+
+**Feature ID:** {{featureId}}
+**Title:** {{title}}
+**Description:** {{description}}
+
+{{#if spec}}
+**Specification:**
+{{spec}}
+{{/if}}
+
+{{#if imagePaths}}
+**Context Images:**
+{{#each imagePaths}}
+- {{this}}
+{{/each}}
+{{/if}}
+
+{{#if dependencies}}
+**Dependencies:**
+This feature depends on: {{dependencies}}
+{{/if}}
+
+{{#if verificationInstructions}}
+**Verification:**
+{{verificationInstructions}}
+{{/if}}
+`;
+
+export const DEFAULT_AUTO_MODE_FOLLOW_UP_PROMPT_TEMPLATE = `## Follow-up on Feature Implementation
+
+{{featurePrompt}}
+
+## Previous Agent Work
+{{previousContext}}
+
+## Follow-up Instructions
+{{followUpInstructions}}
+
+## Task
+Address the follow-up instructions above.
+`;
+
+export const DEFAULT_AUTO_MODE_CONTINUATION_PROMPT_TEMPLATE = `## Continuing Feature Implementation
+
+{{featurePrompt}}
+
+## Previous Context
+{{previousContext}}
+
+## Instructions
+Review the previous work and continue the implementation.
+`;
+
+export const DEFAULT_AUTO_MODE_PIPELINE_STEP_PROMPT_TEMPLATE = `## Pipeline Step: {{stepName}}
+
+### Feature Context
+{{featurePrompt}}
+
+### Previous Work
+{{previousContext}}
+
+### Pipeline Step Instructions
+{{stepInstructions}}
+`;
+
+/**
+ * Default Auto Mode prompts (from auto-mode-service.ts)
+ */
+export const DEFAULT_AUTO_MODE_PROMPTS: ResolvedAutoModePrompts = {
+  planningLite: DEFAULT_AUTO_MODE_PLANNING_LITE,
+  planningLiteWithApproval: DEFAULT_AUTO_MODE_PLANNING_LITE_WITH_APPROVAL,
+  planningSpec: DEFAULT_AUTO_MODE_PLANNING_SPEC,
+  planningFull: DEFAULT_AUTO_MODE_PLANNING_FULL,
+  featurePromptTemplate: DEFAULT_AUTO_MODE_FEATURE_PROMPT_TEMPLATE,
+  followUpPromptTemplate: DEFAULT_AUTO_MODE_FOLLOW_UP_PROMPT_TEMPLATE,
+  continuationPromptTemplate: DEFAULT_AUTO_MODE_CONTINUATION_PROMPT_TEMPLATE,
+  pipelineStepPromptTemplate: DEFAULT_AUTO_MODE_PIPELINE_STEP_PROMPT_TEMPLATE,
+};
+
+/**
+ * ========================================================================
+ * AGENT RUNNER PROMPTS
+ * ========================================================================
+ */
+
+export const DEFAULT_AGENT_SYSTEM_PROMPT = `You are an AI assistant helping users build software. You are part of the Automaker application,
+which is designed to help developers plan, design, and implement software projects autonomously.
+
+**Feature Storage:**
+Features are stored in .automaker/features/{id}/feature.json - each feature has its own folder.
+Use the UpdateFeatureStatus tool to manage features, not direct file edits.
+
+Your role is to:
+- Help users define their project requirements and specifications
+- Ask clarifying questions to better understand their needs
+- Suggest technical approaches and architectures
+- Guide them through the development process
+- Be conversational and helpful
+- Write, edit, and modify code files as requested
+- Execute commands and tests
+- Search and analyze the codebase
+
+**Tools Available:**
+You have access to several tools:
+- UpdateFeatureStatus: Update feature status (NOT file edits)
+- Read/Write/Edit: File operations
+- Bash: Execute commands
+- Glob/Grep: Search codebase
+- WebSearch/WebFetch: Research online
+
+**Important Guidelines:**
+1. When users want to add or modify features, help them create clear feature definitions
+2. Use UpdateFeatureStatus tool to manage features in the backlog
+3. Be proactive in suggesting improvements and best practices
+4. Ask questions when requirements are unclear
+5. Guide users toward good software design principles
+
+Remember: You're a collaborative partner in the development process. Be helpful, clear, and thorough.`;
+
+/**
+ * Default Agent Runner prompts (from agent-service.ts)
+ */
+export const DEFAULT_AGENT_PROMPTS: ResolvedAgentPrompts = {
+  systemPrompt: DEFAULT_AGENT_SYSTEM_PROMPT,
+};
+
+/**
+ * ========================================================================
+ * BACKLOG PLAN PROMPTS
+ * ========================================================================
+ */
+
+export const DEFAULT_BACKLOG_PLAN_SYSTEM_PROMPT = `You are an AI assistant helping to modify a software project's feature backlog.
+You will be given the current list of features and a user request to modify the backlog.
+
+IMPORTANT CONTEXT (automatically injected):
+- Remember to update the dependency graph if deleting existing features
+- Remember to define dependencies on new features hooked into relevant existing ones
+- Maintain dependency graph integrity (no orphaned dependencies)
+- When deleting a feature, identify which other features depend on it
+
+Your task is to analyze the request and produce a structured JSON plan with:
+1. Features to ADD (include title, description, category, and dependencies)
+2. Features to UPDATE (specify featureId and the updates)
+3. Features to DELETE (specify featureId)
+4. A summary of the changes
+5. Any dependency updates needed (removed dependencies due to deletions, new dependencies for new features)
+
+Respond with ONLY a JSON object in this exact format:
+{
+  "plan": {
+    "add": [
+      {
+        "title": "string",
+        "description": "string",
+        "category": "feature" | "bug" | "enhancement" | "refactor",
+        "dependencies": ["featureId1", "featureId2"]
+      }
+    ],
+    "update": [
+      {
+        "featureId": "string",
+        "updates": {
+          "title"?: "string",
+          "description"?: "string",
+          "category"?: "feature" | "bug" | "enhancement" | "refactor",
+          "priority"?: number,
+          "dependencies"?: ["featureId1"]
+        }
+      }
+    ],
+    "delete": ["featureId1", "featureId2"],
+    "summary": "Brief summary of all changes",
+    "dependencyUpdates": [
+      {
+        "featureId": "string",
+        "action": "remove_dependency" | "add_dependency",
+        "dependencyId": "string",
+        "reason": "string"
+      }
+    ]
+  }
+}
+
+Important rules:
+- Only include fields that need to change in updates
+- Ensure dependency references are valid (don't reference deleted features)
+- Provide clear, actionable descriptions
+- Maintain category consistency (feature, bug, enhancement, refactor)
+- When adding dependencies, ensure the referenced features exist or are being added in the same plan
+`;
+
+export const DEFAULT_BACKLOG_PLAN_USER_PROMPT_TEMPLATE = `Current Features in Backlog:
+{{currentFeatures}}
+
+---
+
+User Request: {{userRequest}}
+
+Please analyze the current backlog and the user's request, then provide a JSON plan for the modifications.`;
+
+/**
+ * Default Backlog Plan prompts (from backlog-plan/generate-plan.ts)
+ */
+export const DEFAULT_BACKLOG_PLAN_PROMPTS: ResolvedBacklogPlanPrompts = {
+  systemPrompt: DEFAULT_BACKLOG_PLAN_SYSTEM_PROMPT,
+  userPromptTemplate: DEFAULT_BACKLOG_PLAN_USER_PROMPT_TEMPLATE,
+};
+
+/**
+ * ========================================================================
+ * ENHANCEMENT PROMPTS
+ * ========================================================================
+ * Note: Enhancement prompts are already defined in enhancement.ts
+ * We import and re-export them here for consistency
+ */
+
+import {
+  IMPROVE_SYSTEM_PROMPT,
+  TECHNICAL_SYSTEM_PROMPT,
+  SIMPLIFY_SYSTEM_PROMPT,
+  ACCEPTANCE_SYSTEM_PROMPT,
+} from './enhancement.js';
+
+/**
+ * Default Enhancement prompts (from libs/prompts/src/enhancement.ts)
+ */
+export const DEFAULT_ENHANCEMENT_PROMPTS: ResolvedEnhancementPrompts = {
+  improveSystemPrompt: IMPROVE_SYSTEM_PROMPT,
+  technicalSystemPrompt: TECHNICAL_SYSTEM_PROMPT,
+  simplifySystemPrompt: SIMPLIFY_SYSTEM_PROMPT,
+  acceptanceSystemPrompt: ACCEPTANCE_SYSTEM_PROMPT,
+};
+
+/**
+ * ========================================================================
+ * COMBINED DEFAULTS
+ * ========================================================================
+ */
+
+/**
+ * All default prompts in one object for easy access
+ */
+export const DEFAULT_PROMPTS = {
+  autoMode: DEFAULT_AUTO_MODE_PROMPTS,
+  agent: DEFAULT_AGENT_PROMPTS,
+  backlogPlan: DEFAULT_BACKLOG_PLAN_PROMPTS,
+  enhancement: DEFAULT_ENHANCEMENT_PROMPTS,
+} as const;
--- a/libs/prompts/src/index.ts
+++ b/libs/prompts/src/index.ts
@@ -23,3 +23,40 @@ export {

 // Re-export types from @automaker/types
 export type { EnhancementMode, EnhancementExample } from '@automaker/types';
+
+// Default prompts
+export {
+  DEFAULT_AUTO_MODE_PLANNING_LITE,
+  DEFAULT_AUTO_MODE_PLANNING_LITE_WITH_APPROVAL,
+  DEFAULT_AUTO_MODE_PLANNING_SPEC,
+  DEFAULT_AUTO_MODE_PLANNING_FULL,
+  DEFAULT_AUTO_MODE_FEATURE_PROMPT_TEMPLATE,
+  DEFAULT_AUTO_MODE_FOLLOW_UP_PROMPT_TEMPLATE,
+  DEFAULT_AUTO_MODE_CONTINUATION_PROMPT_TEMPLATE,
+  DEFAULT_AUTO_MODE_PIPELINE_STEP_PROMPT_TEMPLATE,
+  DEFAULT_AUTO_MODE_PROMPTS,
+  DEFAULT_AGENT_SYSTEM_PROMPT,
+  DEFAULT_AGENT_PROMPTS,
+  DEFAULT_BACKLOG_PLAN_SYSTEM_PROMPT,
+  DEFAULT_BACKLOG_PLAN_USER_PROMPT_TEMPLATE,
+  DEFAULT_BACKLOG_PLAN_PROMPTS,
+  DEFAULT_ENHANCEMENT_PROMPTS,
+  DEFAULT_PROMPTS,
+} from './defaults.js';
+
+// Prompt merging utilities
+export {
+  mergeAutoModePrompts,
+  mergeAgentPrompts,
+  mergeBacklogPlanPrompts,
+  mergeEnhancementPrompts,
+  mergeAllPrompts,
+} from './merge.js';
+
+// Re-export resolved prompt types from @automaker/types
+export type {
+  ResolvedAutoModePrompts,
+  ResolvedAgentPrompts,
+  ResolvedBacklogPlanPrompts,
+  ResolvedEnhancementPrompts,
+} from '@automaker/types';
--- a/libs/prompts/src/merge.ts
+++ b/libs/prompts/src/merge.ts
@@ -0,0 +1,130 @@
+/**
+ * Prompt Merging Utilities
+ *
+ * Merges user-customized prompts with built-in defaults.
+ * Used by services to get effective prompts at runtime.
+ *
+ * Custom prompts have an `enabled` flag - when true, the custom value is used.
+ * When false or undefined, the default is used instead.
+ */
+
+import type {
+  PromptCustomization,
+  AutoModePrompts,
+  AgentPrompts,
+  BacklogPlanPrompts,
+  EnhancementPrompts,
+  CustomPrompt,
+  ResolvedAutoModePrompts,
+  ResolvedAgentPrompts,
+  ResolvedBacklogPlanPrompts,
+  ResolvedEnhancementPrompts,
+} from '@automaker/types';
+import {
+  DEFAULT_AUTO_MODE_PROMPTS,
+  DEFAULT_AGENT_PROMPTS,
+  DEFAULT_BACKLOG_PLAN_PROMPTS,
+  DEFAULT_ENHANCEMENT_PROMPTS,
+} from './defaults.js';
+
+/**
+ * Resolve a custom prompt to its effective string value
+ * Returns the custom value if enabled=true, otherwise returns the default
+ */
+function resolvePrompt(custom: CustomPrompt | undefined, defaultValue: string): string {
+  return custom?.enabled ? custom.value : defaultValue;
+}
+
+/**
+ * Merge custom Auto Mode prompts with defaults
+ * Custom prompts override defaults only when enabled=true
+ */
+export function mergeAutoModePrompts(custom?: AutoModePrompts): ResolvedAutoModePrompts {
+  return {
+    planningLite: resolvePrompt(custom?.planningLite, DEFAULT_AUTO_MODE_PROMPTS.planningLite),
+    planningLiteWithApproval: resolvePrompt(
+      custom?.planningLiteWithApproval,
+      DEFAULT_AUTO_MODE_PROMPTS.planningLiteWithApproval
+    ),
+    planningSpec: resolvePrompt(custom?.planningSpec, DEFAULT_AUTO_MODE_PROMPTS.planningSpec),
+    planningFull: resolvePrompt(custom?.planningFull, DEFAULT_AUTO_MODE_PROMPTS.planningFull),
+    featurePromptTemplate: resolvePrompt(
+      custom?.featurePromptTemplate,
+      DEFAULT_AUTO_MODE_PROMPTS.featurePromptTemplate
+    ),
+    followUpPromptTemplate: resolvePrompt(
+      custom?.followUpPromptTemplate,
+      DEFAULT_AUTO_MODE_PROMPTS.followUpPromptTemplate
+    ),
+    continuationPromptTemplate: resolvePrompt(
+      custom?.continuationPromptTemplate,
+      DEFAULT_AUTO_MODE_PROMPTS.continuationPromptTemplate
+    ),
+    pipelineStepPromptTemplate: resolvePrompt(
+      custom?.pipelineStepPromptTemplate,
+      DEFAULT_AUTO_MODE_PROMPTS.pipelineStepPromptTemplate
+    ),
+  };
+}
+
+/**
+ * Merge custom Agent prompts with defaults
+ * Custom prompts override defaults only when enabled=true
+ */
+export function mergeAgentPrompts(custom?: AgentPrompts): ResolvedAgentPrompts {
+  return {
+    systemPrompt: resolvePrompt(custom?.systemPrompt, DEFAULT_AGENT_PROMPTS.systemPrompt),
+  };
+}
+
+/**
+ * Merge custom Backlog Plan prompts with defaults
+ * Custom prompts override defaults only when enabled=true
+ */
+export function mergeBacklogPlanPrompts(custom?: BacklogPlanPrompts): ResolvedBacklogPlanPrompts {
+  return {
+    systemPrompt: resolvePrompt(custom?.systemPrompt, DEFAULT_BACKLOG_PLAN_PROMPTS.systemPrompt),
+    userPromptTemplate: resolvePrompt(
+      custom?.userPromptTemplate,
+      DEFAULT_BACKLOG_PLAN_PROMPTS.userPromptTemplate
+    ),
+  };
+}
+
+/**
+ * Merge custom Enhancement prompts with defaults
+ * Custom prompts override defaults only when enabled=true
+ */
+export function mergeEnhancementPrompts(custom?: EnhancementPrompts): ResolvedEnhancementPrompts {
+  return {
+    improveSystemPrompt: resolvePrompt(
+      custom?.improveSystemPrompt,
+      DEFAULT_ENHANCEMENT_PROMPTS.improveSystemPrompt
+    ),
+    technicalSystemPrompt: resolvePrompt(
+      custom?.technicalSystemPrompt,
+      DEFAULT_ENHANCEMENT_PROMPTS.technicalSystemPrompt
+    ),
+    simplifySystemPrompt: resolvePrompt(
+      custom?.simplifySystemPrompt,
+      DEFAULT_ENHANCEMENT_PROMPTS.simplifySystemPrompt
+    ),
+    acceptanceSystemPrompt: resolvePrompt(
+      custom?.acceptanceSystemPrompt,
+      DEFAULT_ENHANCEMENT_PROMPTS.acceptanceSystemPrompt
+    ),
+  };
+}
+
+/**
+ * Merge all custom prompts with defaults
+ * Returns a complete PromptCustomization with all fields populated
+ */
+export function mergeAllPrompts(custom?: PromptCustomization) {
+  return {
+    autoMode: mergeAutoModePrompts(custom?.autoMode),
+    agent: mergeAgentPrompts(custom?.agent),
+    backlogPlan: mergeBacklogPlanPrompts(custom?.backlogPlan),
+    enhancement: mergeEnhancementPrompts(custom?.enhancement),
+  };
+}
--- a/libs/types/src/index.ts
+++ b/libs/types/src/index.ts
@@ -49,6 +49,21 @@ export { specOutputSchema } from './spec.js';
 // Enhancement types
 export type { EnhancementMode, EnhancementExample } from './enhancement.js';

+// Prompt customization types
+export type {
+  CustomPrompt,
+  AutoModePrompts,
+  AgentPrompts,
+  BacklogPlanPrompts,
+  EnhancementPrompts,
+  PromptCustomization,
+  ResolvedAutoModePrompts,
+  ResolvedAgentPrompts,
+  ResolvedBacklogPlanPrompts,
+  ResolvedEnhancementPrompts,
+} from './prompts.js';
+export { DEFAULT_PROMPT_CUSTOMIZATION } from './prompts.js';
+
 // Settings types and constants
 export type {
  ThemeMode,
--- a/libs/types/src/prompts.ts
+++ b/libs/types/src/prompts.ts
@@ -0,0 +1,153 @@
+/**
+ * Prompt Customization Types
+ *
+ * Defines the structure for customizable AI prompts used throughout the application.
+ * Allows users to modify prompts for Auto Mode, Agent Runner, and Backlog Planning.
+ */
+
+/**
+ * CustomPrompt - A custom prompt with its value and enabled state
+ *
+ * The value is always preserved even when disabled, so users don't lose their work.
+ */
+export interface CustomPrompt {
+  /** The custom prompt text */
+  value: string;
+
+  /** Whether this custom prompt should be used (when false, default is used instead) */
+  enabled: boolean;
+}
+
+/**
+ * AutoModePrompts - Customizable prompts for Auto Mode feature implementation
+ *
+ * Controls how the AI plans and implements features in autonomous mode.
+ */
+export interface AutoModePrompts {
+  /** Planning mode: Quick outline without approval (lite mode) */
+  planningLite?: CustomPrompt;
+
+  /** Planning mode: Quick outline with approval required (lite with approval) */
+  planningLiteWithApproval?: CustomPrompt;
+
+  /** Planning mode: Detailed specification with task breakdown (spec mode) */
+  planningSpec?: CustomPrompt;
+
+  /** Planning mode: Comprehensive Software Design Document (full SDD mode) */
+  planningFull?: CustomPrompt;
+
+  /** Template for building feature implementation prompts */
+  featurePromptTemplate?: CustomPrompt;
+
+  /** Template for follow-up prompts when resuming work */
+  followUpPromptTemplate?: CustomPrompt;
+
+  /** Template for continuation prompts */
+  continuationPromptTemplate?: CustomPrompt;
+
+  /** Template for pipeline step execution prompts */
+  pipelineStepPromptTemplate?: CustomPrompt;
+}
+
+/**
+ * AgentPrompts - Customizable prompts for Agent Runner (chat mode)
+ *
+ * Controls the AI's behavior in interactive chat sessions.
+ */
+export interface AgentPrompts {
+  /** System prompt defining the agent's role and behavior in chat */
+  systemPrompt?: CustomPrompt;
+}
+
+/**
+ * BacklogPlanPrompts - Customizable prompts for Kanban board planning
+ *
+ * Controls how the AI modifies the feature backlog via the Plan button.
+ */
+export interface BacklogPlanPrompts {
+  /** System prompt for backlog plan generation (defines output format and rules) */
+  systemPrompt?: CustomPrompt;
+
+  /** Template for user prompt (includes current features and user request) */
+  userPromptTemplate?: CustomPrompt;
+}
+
+/**
+ * EnhancementPrompts - Customizable prompts for feature description enhancement
+ *
+ * Controls how the AI enhances feature titles and descriptions.
+ */
+export interface EnhancementPrompts {
+  /** System prompt for "improve" mode (vague → clear) */
+  improveSystemPrompt?: CustomPrompt;
+
+  /** System prompt for "technical" mode (add technical details) */
+  technicalSystemPrompt?: CustomPrompt;
+
+  /** System prompt for "simplify" mode (verbose → concise) */
+  simplifySystemPrompt?: CustomPrompt;
+
+  /** System prompt for "acceptance" mode (add acceptance criteria) */
+  acceptanceSystemPrompt?: CustomPrompt;
+}
+
+/**
+ * PromptCustomization - Complete set of customizable prompts
+ *
+ * All fields are optional. Undefined values fall back to built-in defaults.
+ * Stored in GlobalSettings to allow user customization.
+ */
+export interface PromptCustomization {
+  /** Auto Mode prompts (feature implementation) */
+  autoMode?: AutoModePrompts;
+
+  /** Agent Runner prompts (interactive chat) */
+  agent?: AgentPrompts;
+
+  /** Backlog planning prompts (Plan button) */
+  backlogPlan?: BacklogPlanPrompts;
+
+  /** Enhancement prompts (feature description improvement) */
+  enhancement?: EnhancementPrompts;
+}
+
+/**
+ * Default empty prompt customization (all undefined → use built-in defaults)
+ */
+export const DEFAULT_PROMPT_CUSTOMIZATION: PromptCustomization = {
+  autoMode: {},
+  agent: {},
+  backlogPlan: {},
+  enhancement: {},
+};
+
+/**
+ * Resolved prompt types - all fields are required strings (ready to use)
+ * Used for default prompts and merged prompts after resolving custom values
+ */
+export interface ResolvedAutoModePrompts {
+  planningLite: string;
+  planningLiteWithApproval: string;
+  planningSpec: string;
+  planningFull: string;
+  featurePromptTemplate: string;
+  followUpPromptTemplate: string;
+  continuationPromptTemplate: string;
+  pipelineStepPromptTemplate: string;
+}
+
+export interface ResolvedAgentPrompts {
+  systemPrompt: string;
+}
+
+export interface ResolvedBacklogPlanPrompts {
+  systemPrompt: string;
+  userPromptTemplate: string;
+}
+
+export interface ResolvedEnhancementPrompts {
+  improveSystemPrompt: string;
+  technicalSystemPrompt: string;
+  simplifySystemPrompt: string;
+  acceptanceSystemPrompt: string;
+}
--- a/libs/types/src/settings.ts
+++ b/libs/types/src/settings.ts
@@ -7,6 +7,7 @@
 */

 import type { AgentModel } from './model.js';
+import type { PromptCustomization } from './prompts.js';

 // Re-export AgentModel for convenience
 export type { AgentModel };
@@ -360,6 +361,10 @@ export interface GlobalSettings {
  mcpAutoApproveTools?: boolean;
  /** Allow unrestricted tools when MCP servers are enabled (don't filter allowedTools) */
  mcpUnrestrictedTools?: boolean;
+
+  // Prompt Customization
+  /** Custom prompts for Auto Mode, Agent Runner, Backlog Planning, and Enhancements */
+  promptCustomization?: PromptCustomization;
 }

 /**
				`@@ -0,0 +1 @@`
				`export { PromptCustomizationSection } from './prompt-customization-section';`