feat: add cover letter generation command

Add /write-cover-letter slash command that generates tailored cover
letters based on application strategy (application.md) and applicant
profile (profile.md). Features:

- Auto-validates application before generation (stops if incomplete)
- Protects existing cover-letter.md (requires --force to overwrite)
- Generates 300-400 word cover letter with standard structure
- Applies tone from application.md (Formal/Balanced/Casual)
- Infers language from context (German/English)
- Uses match strategy to emphasize relevant experiences
- Incorporates company research and key messages
- Supports flags: --skip-validation, --force, --help

This is the first document generation command in the workflow.

OpenSpec: add-cover-letter-generation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/CLAUDE.md

@@ -194,14 +194,34 @@ When helping with job applications, follow this comprehensive workflow:
 - Get warnings if input/ folder is empty or application seems unpopulated
 - **Must pass before document generation**
 
-### 6. Content Generation (FUTURE)
-- Generate CV/cover letter/email based on `application.md` strategy
-- Emphasize relevant experience from `profile.md`
-- Incorporate keywords from the job description naturally
-- Maintain factual accuracy - use only verified information from `profile.md`
-- **Note**: Document generation will be implemented in a future update
+### 6. Generate Cover Letter
+- Run `/write-cover-letter` to generate a tailored cover letter
+- System automatically validates application first (stops if incomplete)
+- Checks if cover-letter.md already exists (prevents overwriting)
+- Generates 300-400 word cover letter using:
+  - Profile.md for applicant background and achievements
+  - Application.md for job strategy, key messages, and tone
+- Standard structure: Opening → Why this role → What you bring → Cultural fit → Closing
+- Applies appropriate tone (Formal/Balanced/Casual) from application.md
+- Saves to `cover-letter.md` in application folder
+- Flags available: `--skip-validation`, `--force` (overwrite existing)
 
-### 7. Quality Assurance
+### 7. Review and Refine Cover Letter
+- Read generated cover-letter.md carefully
+- Verify factual accuracy (names, dates, achievements)
+- Add personal touches or additional insights
+- Ensure authentic voice and genuine enthusiasm
+- Proofread for typos and flow
+
+### 8. Generate CV (FUTURE)
+- Generate tailored CV based on application.md strategy (coming soon)
+- Emphasize relevant experience from profile.md
+- Incorporate keywords naturally
+
+### 9. Generate Application Email (FUTURE)
+- Create professional application email (coming soon)
+
+### 10. Quality Assurance
 - Verify all company names, dates, and facts are correct
 - Ensure consistency between all documents (CV ↔ cover letter ↔ email)
 - Check that tone matches the target company culture
@@ -216,12 +236,22 @@ When helping with job applications, follow this comprehensive workflow:
 - Keep formatting simple and ATS-friendly
 - Use quantifiable achievements when available
 
-### Cover Letter
-- Structure: Opening → Why this role → What you bring → Cultural fit → Closing
-- Length: Aim for 1 page (3-4 paragraphs)
-- Tone: Match company culture (formal/balanced/casual)
-- Personalize: Reference specific aspects of the job/company
-- Connect: Link applicant's experience to job requirements
+### Cover Letter (Generated by `/write-cover-letter`)
+- **Structure**: Opening → Why this role → What you bring → Cultural fit → Closing
+- **Length**: 300-400 words (approximately 1 page)
+- **Tone**: Applied from application.md tone assessment (Formal/Balanced/Casual)
+- **Language**: Inferred from job posting context (German/English)
+- **Content**:
+  - Use ONLY authentic information from profile.md (no fabrication)
+  - Incorporate 2-3 key experiences from match strategy
+  - Reference company research and culture insights from application.md
+  - Natural incorporation of keywords from job description
+  - Company-specific personalization (values, news, projects)
+- **Quality checks**:
+  - Automatic validation before generation
+  - Protection against overwriting existing work
+  - Word count target enforcement (300-400 words)
+  - Factual accuracy verification
 
 ### Application Email
 - Keep it short (3-4 sentences maximum)
@@ -263,6 +293,7 @@ Adjust recommendations based on the target market if the user specifies a differ
 - `/new-application "Company - Job Title"` - Create a new application workspace with organized folder structure
 - `/populate-application` - Analyze input documents and populate application.md with job info, research, and strategy
 - `/validate-application [optional-app-name]` - Validate that application.md is complete before document generation
+- `/write-cover-letter [optional-app-name] [--skip-validation] [--force]` - Generate a tailored cover letter based on application strategy
 
 ## Example Usage
 
@@ -277,8 +308,9 @@ Adjust recommendations based on the target market if the user specifies a differ
 4. When user has added documents: "Navigate to the application folder and run `/populate-application`"
 5. After population completes: "Review `application.md` to see the analysis and strategy"
 6. Validation step: "Run `/validate-application` to ensure the application is complete"
-7. If validation passes: Ready for document generation
-8. Future: Generate tailored CV, cover letter, and email based on `application.md`
+7. If validation passes: "Generate cover letter with `/write-cover-letter`"
+8. After generation: "Review cover-letter.md and personalize as needed"
+9. Future: Generate tailored CV and application email
 
 ### Example 2: Quick Document Request (Legacy Flow)
 
@@ -304,6 +336,34 @@ Adjust recommendations based on the target market if the user specifies a differ
 4. If validation fails (❌): Show specific issues like "Organization Name: Contains placeholder '[To be filled]'" and suggest "Please update application.md or run `/populate-application` if you have documents in input/"
 5. Provide clear next steps based on validation result
 
+### Example 4: Generating a Cover Letter
+
+**User**: "Generate cover letter for my TechCorp application"
+
+**Claude Code should**:
+1. If user is in application folder: Run `/write-cover-letter` (auto-detects location)
+2. If user is elsewhere: Run `/write-cover-letter 2025-11-02-TechCorp-Software-Engineer`
+3. System automatically validates application first:
+   - If validation fails: Stop and show errors, suggest fixing or using `--skip-validation`
+   - If validation passes: Proceed to generation
+4. Check for existing cover-letter.md:
+   - If exists: Stop and suggest using `--force` flag to overwrite
+   - If doesn't exist: Proceed to generation
+5. Generate cover letter:
+   - Read profile.md for applicant background
+   - Read application.md for job strategy and tone
+   - Generate 300-400 word tailored cover letter
+   - Save to cover-letter.md
+6. Show success: "✅ Cover letter saved: cover-letter.md. Generated 376 words. Next: Review and personalize."
+
+**User**: "Regenerate the cover letter with different approach"
+
+**Claude Code should**:
+1. Run `/write-cover-letter --force` to overwrite existing file
+2. System warns: "⚠️ Overwriting existing cover letter"
+3. Proceeds with generation
+4. Suggests: "Review the new version and keep whichever you prefer"
+
 ## Updating the Profile
 
 If you notice missing or outdated information during application preparation: