plan-first（首先计划）

Plan First - Structured Problem Solving

Plan First implements the Plan-and-Solve research paradigm for tackling complex tasks systematically.

The core insight: Generative AI performs better when it plans before acting, especially on multi-step tasks where dependencies exist between steps.

The Analogy: Architect vs. Builder

When to Use Plan First

Perfect for:

• 🏗️ Multi-step coding tasks (implement feature X that requires Y, Z, W)
• 📝 Complex writing (reports, documentation with sections)
• 🔬 Analysis tasks (data analysis with multiple phases)
• 🧩 Problem-solving (math, logic, puzzles with steps)
• 📋 Project planning (breaking down large initiatives)

Skip for:

• ⚡ Single-step tasks ("What is 2+2?")
• 🎯 Direct questions ("What is the capital of France?")
• 🔄 Pure exploration (brainstorming without structure)

The Workflow

Step 1: Generate the Plan

Before ANY execution, create a detailed plan:

TASK: "Build a user authentication system"

PLAN:
1. [SETUP] Initialize database schema for users table
   - Dependencies: None
   - Success criteria: Migration runs without errors

2. [IMPLEMENTATION] Create password hashing utilities
   - Dependencies: Step 1 complete
   - Success criteria: bcrypt integration works

3. [IMPLEMENTATION] Build login endpoint
   - Dependencies: Steps 1, 2
   - Success criteria: Returns JWT on valid credentials

4. [IMPLEMENTATION] Build signup endpoint
   - Dependencies: Steps 1, 2
   - Success criteria: Creates user, returns token

5. [INTEGRATION] Add middleware for protected routes
   - Dependencies: Steps 3, 4
   - Success criteria: Unauthorized requests rejected

6. [TESTING] Write comprehensive tests
   - Dependencies: Steps 3, 4, 5
   - Success criteria: All tests pass

Step 2: Validate the Plan

Self-check before proceeding:

• [ ] Are steps in logical order?
• [ ] Are dependencies clearly marked?
• [ ] Is each step specific and actionable?
• [ ] Are success criteria verifiable?
• [ ] Did I miss any prerequisite steps?

If gaps found: Revise the plan first.

Step 3: Execute Step by Step

Execute ONE step at a time, in order:

Executing Step 1: Initialize database schema
✓ Run: CREATE TABLE users...
✓ Verify: Table exists with correct columns
✓ Mark complete

Executing Step 2: Create password hashing utilities
✓ Run: Implement hash_password(), verify_password()
✓ Verify: Unit tests pass
✓ Mark complete

... continue until all steps complete

Step 4: Handle Deviations

If a step fails:

1. Analyze why it failed
2. Revise plan if needed (add missing steps, reorder)
3. Resume from current step

If requirements change:

1. Stop execution
2. Revise remaining plan
3. Continue with updated plan

Plan Format Template

## Task
[Clear statement of what needs to be done]

## Plan

### Step N: [Action Verb] [What to do]
**Dependencies:** [List prerequisite steps]
**Approach:** [How to accomplish this step]
**Verification:** [How to confirm success]
**Files/Tools:** [What to modify or use]

---

### Step 1: [SETUP/IMPLEMENTATION/ANALYSIS/TESTING] Description
**Dependencies:** None
**Approach:** 
- Detail 1
- Detail 2
**Verification:** [Specific test or check]
**Files:** [Files to create/modify]

### Step 2: ...
[Continue for all steps]

## Risk Analysis
**Potential blockers:** [What could go wrong]
**Mitigation:** [How to handle issues]

## Rollback Plan
**If fails at step N:** [How to undo/reset]

Examples

Example 1: Code Implementation

Task: "Add email verification to signup flow"

## Plan

### Step 1: [SETUP] Create email_tokens table
**Dependencies:** None
**Approach:** 
- Create migration for email_tokens table
- Fields: id, user_id, token, expires_at, used
**Verification:** Migration runs, table structure correct
**Files:** migrations/003_email_tokens.sql

### Step 2: [IMPLEMENTATION] Add email sending utility
**Dependencies:** Step 1
**Approach:**
- Create utils/email.py with send_verification_email()
- Use SMTP or SendGrid
- Include token in email link
**Verification:** Can send test email successfully
**Files:** utils/email.py

### Step 3: [IMPLEMENTATION] Modify signup endpoint
**Dependencies:** Steps 1, 2
**Approach:**
- After user creation, generate token
- Send verification email
- Return "check your email" response
**Verification:** Signup creates token and sends email
**Files:** routes/auth.py

### Step 4: [IMPLEMENTATION] Create verify endpoint
**Dependencies:** Step 1
**Approach:**
- GET /verify-email?token=xxx
- Check token valid and not expired
- Mark user as verified
**Verification:** Clicking link marks user verified
**Files:** routes/auth.py

### Step 5: [INTEGRATION] Add verified check to login
**Dependencies:** Step 4
**Approach:**
- Modify login to require verified=True
- Return appropriate error if unverified
**Verification:** Unverified users can't login
**Files:** routes/auth.py

### Step 6: [TESTING] Write tests
**Dependencies:** Steps 1-5
**Approach:**
- Test signup creates token
- Test email sent
- Test verification works
- Test unverified can't login
**Verification:** All tests pass
**Files:** tests/test_auth.py

Example 2: Writing Task

Task: "Write annual report for engineering team"

## Plan

### Step 1: [ANALYSIS] Gather metrics
**Dependencies:** None
**Approach:**
- Pull deployment frequency from CI/CD
- Get incident data from monitoring
- Collect code review stats
**Verification:** Have all data points needed
**Files:** data/raw_metrics.json

### Step 2: [DRAFTING] Write executive summary
**Dependencies:** Step 1
**Approach:**
- Highlight key achievements
- Include year-over-year comparison
- Keep to 1 page
**Verification:** Covers all major points
**Files:** report/executive_summary.md

### Step 3: [DRAFTING] Write detailed sections
**Dependencies:** Step 2 (for tone consistency)
**Approach:**
- Infrastructure improvements
- Team growth and hiring
- Process optimizations
- Major projects delivered
**Verification:** Each section has data + narrative
**Files:** report/sections/*.md

### Step 4: [INTEGRATION] Compile and format
**Dependencies:** Steps 2, 3
**Approach:**
- Combine sections
- Add table of contents
- Apply company template
**Verification:** Document is complete and formatted
**Files:** report/annual_report_2024.md

### Step 5: [REVIEW] Self-review and polish
**Dependencies:** Step 4
**Approach:**
- Check for typos
- Verify all numbers accurate
- Ensure flow between sections
**Verification:** Ready for stakeholder review
**Files:** [same]

Example 3: Data Analysis

Task: "Analyze customer churn for Q4"

## Plan

### Step 1: [DATA] Extract customer data
**Dependencies:** None
**Approach:**
- Query database for customers active in Q3
- Get their Q4 activity status
- Include subscription tier, signup date
**Verification:** Dataset has expected row count
**Files:** data/customers_q4.csv

### Step 2: [ANALYSIS] Calculate churn rate
**Dependencies:** Step 1
**Approach:**
- Define churn: no activity in Q4
- Calculate overall rate
- Break down by tier, acquisition channel
**Verification:** Numbers match expectations
**Files:** analysis/churn_basic.py

### Step 3: [ANALYSIS] Identify patterns
**Dependencies:** Step 2
**Approach:**
- Time-series analysis of churn
- Correlation with features
- Segment analysis
**Verification:** Charts show clear patterns
**Files:** analysis/churn_patterns.ipynb

### Step 4: [SYNTHESIS] Create recommendations
**Dependencies:** Step 3
**Approach:**
- Based on patterns, propose interventions
- Prioritize by impact/effort
- Include success metrics
**Verification:** Recommendations are actionable
**Files:** report/recommendations.md

### Step 5: [DELIVERY] Create presentation
**Dependencies:** Steps 2, 3, 4
**Approach:**
- Executive summary slide
- Key findings with charts
- Recommendations with impact
**Verification:** Stakeholders can act on it
**Files:** presentation/churn_analysis_q4.pptx

Best Practices

1. Make Steps Concrete

❌ Vague: "Set up authentication" ✅ Concrete: "Create users table with bcrypt password hashing"

2. Define Clear Verification

Every step needs a pass/fail check:

• "Tests pass"
• "Database table exists with correct schema"
• "Can send test email successfully"
• "Response time < 200ms"

3. Keep Steps Small

Break large steps into smaller ones:

❌ "Build entire API" ✅

• "Create database schema"
• "Implement GET endpoint"
• "Implement POST endpoint"
• "Add validation"
• "Write tests"

4. Mark Dependencies Explicitly

This prevents trying to build on foundations that don't exist.

5. Plan for Failure

Include what to do if a step fails:

• Rollback procedure
• Alternative approaches
• When to stop and reassess

Comparison: Direct vs Plan-First

Task: "Build a REST API for todos"

When Plans Change

Mid-execution discovery: "Actually we need OAuth, not simple auth"

1. Stop current execution
2. Reassess remaining plan
3. Add OAuth-specific steps
4. Update dependencies
5. Resume with revised plan

Don't wing it. Update the plan.

Integration with Other Skills

Plan First + Team Code:

1. Generate master plan
2. Delegate parallelizable steps to agents
3. Execute dependency-aware

Plan First + Self-Critique:

1. Generate plan
2. Critique the plan ("Am I missing anything?")
3. Revise
4. Execute

Quick Start Template

## Task
[Your task here]

## Plan

### Step 1: [VERB] Description
**Dependencies:** None
**Approach:**
- 
- 
**Verification:** 
**Files:** 

### Step 2: [VERB] Description
**Dependencies:** Step 1
**Approach:**
- 
- 
**Verification:** 
**Files:** 

[Continue...]

## Risk Analysis
**Blockers:** 
**Mitigation:** 

## Rollback
**If fails:** 

References

• Research: "Plan-and-Solve Prompting: Improving Zero-Shot Chain-of-Thought Reasoning by Large Language Models" (Wang et al., 2023)
• Related: Chain-of-Thought (CoT), Tree-of-Thought (ToT), ReAct
• See references/examples.md for more detailed examples