Create a New Pattern

You are creating a new pattern for battle-tested-patterns. Follow each step in order. Do NOT skip source verification. Reference SOP 01 for the full checklist.

Step 1: Topic Validation

Ask these questions before proceeding:

1. What is the pattern name?
2. Can you name ≥ 2 production projects that use it (with source links)?
3. Is it cross-language (not specific to one language/framework)?
4. Is it a code-level technique (not purely architectural)?
5. Does it NOT duplicate an existing pattern in docs/patterns/?

If any answer is "no", stop and explain why this pattern doesn't fit.

Step 2: Source Code Location

For each production project:

1. Search the project repo for the exact usage
2. Get the GitHub URL with line numbers: https://github.com/{org}/{repo}/blob/main/{path}#L{start}-L{end}
3. Verify with curl -sI <url> | head -1 — must return HTTP 200
4. Read the code to confirm your understanding
5. Write a Production Proof description specific enough to learn WITHOUT clicking the link

CRITICAL: Never fabricate a URL. If you cannot verify a link, write <!-- TODO: verify source link --> instead.

Step 3: Write the Document

Create docs/patterns/<pattern-name>/index.md with ALL required sections:

# Pattern: [Name]
## One Liner          ← ≤ 30 English words, capture WHY not just WHAT
## Core Idea          ← concept + diagram (choose best representation for this pattern)
## Production Proof   ← table with ≥ 2 verified URLs, descriptions show HOW not just WHAT
## Implementation     ← TypeScript (required) + ≥ 1 other language in ::: code-group
## Exercises          ← table with basic + intermediate exercise links
## When to Use        ← ≥ 3 concrete scenarios
## When NOT to Use    ← ≥ 2 concrete alternatives
## More Production Uses ← bullet list with repo links
## Challenge Questions ← 3-4 scenario Q&A using ::: details syntax

Diagram Guidelines

• Choose the representation that best matches the pattern's nature:
  • Ring/circular → for hash rings, ring buffers
  • Timeline → for temporal patterns (WAL, MVCC, retry)
  • State diagram → for state machines, circuit breakers (use mermaid)
  • Tree → for tries, heaps, B-trees
  • Box-and-arrow → for data structures (LRU, skip list)
• ASCII text blocks: every box border must be vertically aligned
• ZH docs: CJK characters = 2 display columns; compensate with fewer spaces
• Verify alignment in a monospace font before committing

Step 4: Implement

In the ::: code-group block:

• TypeScript (required) — idiomatic, strict types, no any
• At least one of: Rust / Go / Python
• Each implementation must be idiomatic, not a line-by-line translation
• Go: do NOT add import blocks — the verify-code script auto-detects imports
• Rust: wrap standalone code in fn main() or use pub struct/pub fn
• Verify: pnpm verify-code

Step 5: Design Exercises

Create in exercises/typescript/<pattern>/:

• 01-basic.test.ts — basic pattern mechanics (required)
• 02-intermediate.test.ts — real-world application scenario (required)
• Use TODO-stub format with // TODO: implement markers
• Include working implementations so CI passes
• Separator: // ─── Tests (do not modify below this line) ───────────────────────
• 4-5 meaningful test cases per exercise
• Verify: pnpm test:exercises AND pnpm typecheck

Step 6: Write Challenge Questions

Add ## Challenge Questions at the end of the EN doc:

• 3-4 questions using ::: details Q1: [question] ... ::: syntax
• Questions test understanding through production scenarios
• Verify factual accuracy of all answers
• Escape | in table cells, use × instead of * for multiplication
• Copy to ZH doc with header ## 挑战题, translate Q&A to Chinese (keep technical terms and code in English)

Step 7: Create Chinese Translation

Create docs/zh/patterns/<pattern-name>/index.md:

• Translate structural content (headings, explanations, When to Use)
• Keep code blocks identical to English
• Keep Production Proof links identical
• Challenge Questions: translate questions + answers to Chinese, keep technical terms/code in English
• ASCII diagrams: use English labels inside box-drawing diagrams (no CJK in diagrams)

Step 8: Update Navigation

All of these must be updated:

• docs/.vitepress/config.ts — BOTH English and Chinese sidebar
• docs/index.md — English homepage pattern table
• docs/zh/index.md — Chinese homepage pattern table
• README.md — pattern table + cheat sheet table
• README.zh-CN.md — pattern table + cheat sheet table
• docs/by-project/*.md — add to ALL relevant project pages (React, Linux, Go, Redis, etc.)
• docs/by-project/more-projects.md — add if project not covered by specific pages
• docs/zh/by-project/*.md — sync Chinese versions
• README.md cheat sheet — add to correct category table
• README.zh-CN.md cheat sheet — sync Chinese version
• docs/guide/pattern-connections.md + ZH — update if pattern fits a system case study

Step 9: Full Verification

Run ALL checks before committing:

pnpm check         # All checks (lint + typecheck + test + verify-code + verify-mermaid + check:content)
pnpm build         # VitePress builds

Step 10: Site Accessibility Verification

After build, verify all new pages are reachable:

• ls docs/.vitepress/dist/patterns/<name>/index.html — EN page exists
• ls docs/.vitepress/dist/zh/patterns/<name>/index.html — ZH page exists
• After deploy, spot-check live URLs in both languages

Step 11: Commit and Tag

• Commit message: feat: add <pattern-name> pattern
• If adding multiple patterns: one commit per batch with list
• Push and verify CI is green before tagging
• Tag: git tag -a v1.X.0 -m "description" + git push origin v1.X.0