Initial commit

2026-04-27 18:40:30 +08:00
commit 2120774b05
112 changed files with 12308 additions and 0 deletions
@@ -0,0 +1,105 @@
+# Code Reuse Thinking Guide
+
+> **Purpose**: Stop and think before creating new code - does it already exist?
+
+---
+
+## The Problem
+
+**Duplicated code is the #1 source of inconsistency bugs.**
+
+When you copy-paste or rewrite existing logic:
+- Bug fixes don't propagate
+- Behavior diverges over time
+- Codebase becomes harder to understand
+
+---
+
+## Before Writing New Code
+
+### Step 1: Search First
+
+```bash
+# Search for similar function names
+grep -r "functionName" .
+
+# Search for similar logic
+grep -r "keyword" .
+```
+
+### Step 2: Ask These Questions
+
+| Question | If Yes... |
+|----------|-----------|
+| Does a similar function exist? | Use or extend it |
+| Is this pattern used elsewhere? | Follow the existing pattern |
+| Could this be a shared utility? | Create it in the right place |
+| Am I copying code from another file? | **STOP** - extract to shared |
+
+---
+
+## Common Duplication Patterns
+
+### Pattern 1: Copy-Paste Functions
+
+**Bad**: Copying a validation function to another file
+
+**Good**: Extract to shared utilities, import where needed
+
+### Pattern 2: Similar Components
+
+**Bad**: Creating a new component that's 80% similar to existing
+
+**Good**: Extend existing component with props/variants
+
+### Pattern 3: Repeated Constants
+
+**Bad**: Defining the same constant in multiple files
+
+**Good**: Single source of truth, import everywhere
+
+---
+
+## When to Abstract
+
+**Abstract when**:
+- Same code appears 3+ times
+- Logic is complex enough to have bugs
+- Multiple people might need this
+
+**Don't abstract when**:
+- Only used once
+- Trivial one-liner
+- Abstraction would be more complex than duplication
+
+---
+
+## After Batch Modifications
+
+When you've made similar changes to multiple files:
+
+1. **Review**: Did you catch all instances?
+2. **Search**: Run grep to find any missed
+3. **Consider**: Should this be abstracted?
+
+---
+
+## Gotcha: Asymmetric Mechanisms Producing Same Output
+
+**Problem**: When two different mechanisms must produce the same file set (e.g., recursive directory copy for init vs. manual `files.set()` for update), structural changes (renaming, moving, adding subdirectories) only propagate through the automatic mechanism. The manual one silently drifts.
+
+**Symptom**: Init works perfectly, but update creates files at wrong paths or misses files entirely.
+
+**Prevention checklist**:
+- [ ] When migrating directory structures, search for ALL code paths that reference the old structure
+- [ ] If one path is auto-derived (glob/copy) and another is manually listed, the manual one needs updating
+- [ ] Add a regression test that compares outputs from both mechanisms
+
+---
+
+## Checklist Before Commit
+
+- [ ] Searched for existing similar code
+- [ ] No copy-pasted logic that should be shared
+- [ ] Constants defined in one place
+- [ ] Similar patterns follow same structure
@@ -0,0 +1,94 @@
+# Cross-Layer Thinking Guide
+
+> **Purpose**: Think through data flow across layers before implementing.
+
+---
+
+## The Problem
+
+**Most bugs happen at layer boundaries**, not within layers.
+
+Common cross-layer bugs:
+- API returns format A, frontend expects format B
+- Database stores X, service transforms to Y, but loses data
+- Multiple layers implement the same logic differently
+
+---
+
+## Before Implementing Cross-Layer Features
+
+### Step 1: Map the Data Flow
+
+Draw out how data moves:
+
+```
+Source → Transform → Store → Retrieve → Transform → Display
+```
+
+For each arrow, ask:
+- What format is the data in?
+- What could go wrong?
+- Who is responsible for validation?
+
+### Step 2: Identify Boundaries
+
+| Boundary | Common Issues |
+|----------|---------------|
+| API ↔ Service | Type mismatches, missing fields |
+| Service ↔ Database | Format conversions, null handling |
+| Backend ↔ Frontend | Serialization, date formats |
+| Component ↔ Component | Props shape changes |
+
+### Step 3: Define Contracts
+
+For each boundary:
+- What is the exact input format?
+- What is the exact output format?
+- What errors can occur?
+
+---
+
+## Common Cross-Layer Mistakes
+
+### Mistake 1: Implicit Format Assumptions
+
+**Bad**: Assuming date format without checking
+
+**Good**: Explicit format conversion at boundaries
+
+### Mistake 2: Scattered Validation
+
+**Bad**: Validating the same thing in multiple layers
+
+**Good**: Validate once at the entry point
+
+### Mistake 3: Leaky Abstractions
+
+**Bad**: Component knows about database schema
+
+**Good**: Each layer only knows its neighbors
+
+---
+
+## Checklist for Cross-Layer Features
+
+Before implementation:
+- [ ] Mapped the complete data flow
+- [ ] Identified all layer boundaries
+- [ ] Defined format at each boundary
+- [ ] Decided where validation happens
+
+After implementation:
+- [ ] Tested with edge cases (null, empty, invalid)
+- [ ] Verified error handling at each boundary
+- [ ] Checked data survives round-trip
+
+---
+
+## When to Create Flow Documentation
+
+Create detailed flow docs when:
+- Feature spans 3+ layers
+- Multiple teams are involved
+- Data format is complex
+- Feature has caused bugs before
@@ -0,0 +1,79 @@
+# Thinking Guides
+
+> **Purpose**: Expand your thinking to catch things you might not have considered.
+
+---
+
+## Why Thinking Guides?
+
+**Most bugs and tech debt come from "didn't think of that"**, not from lack of skill:
+
+- Didn't think about what happens at layer boundaries → cross-layer bugs
+- Didn't think about code patterns repeating → duplicated code everywhere
+- Didn't think about edge cases → runtime errors
+- Didn't think about future maintainers → unreadable code
+
+These guides help you **ask the right questions before coding**.
+
+---
+
+## Available Guides
+
+| Guide | Purpose | When to Use |
+|-------|---------|-------------|
+| [Code Reuse Thinking Guide](./code-reuse-thinking-guide.md) | Identify patterns and reduce duplication | When you notice repeated patterns |
+| [Cross-Layer Thinking Guide](./cross-layer-thinking-guide.md) | Think through data flow across layers | Features spanning multiple layers |
+
+---
+
+## Quick Reference: Thinking Triggers
+
+### When to Think About Cross-Layer Issues
+
+- [ ] Feature touches 3+ layers (API, Service, Component, Database)
+- [ ] Data format changes between layers
+- [ ] Multiple consumers need the same data
+- [ ] You're not sure where to put some logic
+
+→ Read [Cross-Layer Thinking Guide](./cross-layer-thinking-guide.md)
+
+### When to Think About Code Reuse
+
+- [ ] You're writing similar code to something that exists
+- [ ] You see the same pattern repeated 3+ times
+- [ ] You're adding a new field to multiple places
+- [ ] **You're modifying any constant or config**
+- [ ] **You're creating a new utility/helper function** ← Search first!
+
+→ Read [Code Reuse Thinking Guide](./code-reuse-thinking-guide.md)
+
+---
+
+## Pre-Modification Rule (CRITICAL)
+
+> **Before changing ANY value, ALWAYS search first!**
+
+```bash
+# Search for the value you're about to change
+grep -r "value_to_change" .
+```
+
+This single habit prevents most "forgot to update X" bugs.
+
+---
+
+## How to Use This Directory
+
+1. **Before coding**: Skim the relevant thinking guide
+2. **During coding**: If something feels repetitive or complex, check the guides
+3. **After bugs**: Add new insights to the relevant guide (learn from mistakes)
+
+---
+
+## Contributing
+
+Found a new "didn't think of that" moment? Add it to the relevant guide.
+
+---
+
+**Core Principle**: 30 minutes of thinking saves 3 hours of debugging.