# pds.js Refactor Implementation Plan

> **For Claude:** REQUIRED SUB-SKILL: Use superpowers:executing-plans to implement this plan task-by-task.

**Goal:** Improve pds.js maintainability through consolidated CBOR encoding, JSDoc documentation, route table pattern, and clarifying comments.

**Architecture:** Single-file refactor preserving current dependency order. Extract shared `encodeHead` helper for CBOR encoders. Replace `PersonalDataServer.fetch` if/else chain with declarative route table. Add JSDoc to exported functions and "why" comments to protocol-specific logic.

**Tech Stack:** JavaScript (ES modules), Cloudflare Workers, JSDoc

---

## Task 1: Add CBOR Constants

**Files:**
- Modify: `src/pds.js:1-12`

**Step 1: Write test for constants usage**

No new test needed — existing CBOR tests will verify constants work correctly.

**Step 2: Add constants section at top of file**

Insert before the CID wrapper class:

```javascript
// === CONSTANTS ===
// CBOR primitive markers (RFC 8949)
const CBOR_FALSE = 0xf4
const CBOR_TRUE = 0xf5
const CBOR_NULL = 0xf6

// DAG-CBOR CID link tag
const CBOR_TAG_CID = 42
```

**Step 3: Update cborEncode to use constants**

Replace in `cborEncode` function:
- `parts.push(0xf6)` → `parts.push(CBOR_NULL)`
- `parts.push(0xf5)` → `parts.push(CBOR_TRUE)`
- `parts.push(0xf4)` → `parts.push(CBOR_FALSE)`

**Step 4: Update cborEncodeDagCbor to use constants**

Same replacements, plus:
- `parts.push(0xd8, 42)` → `parts.push(0xd8, CBOR_TAG_CID)`

**Step 5: Update cborEncodeMstNode to use constants**

Same replacements for null/true/false and tag 42.

**Step 6: Run tests to verify**

Run: `npm test`
Expected: All CBOR tests pass

**Step 7: Commit**

```bash
git add src/pds.js
git commit -m "refactor: extract CBOR constants for clarity"
```

---

## Task 2: Extract Shared encodeHead Helper

**Files:**
- Modify: `src/pds.js` (CBOR ENCODING section)

**Step 1: Write test for large integer encoding**

Already exists — `test/pds.test.js` has "encodes large integers >= 2^31 without overflow"

**Step 2: Extract shared encodeHead function**

Add after constants section, before `cborEncode`:

```javascript
/**
 * Encode CBOR type header (major type + length)
 * @param {number[]} parts - Array to push bytes to
 * @param {number} majorType - CBOR major type (0-7)
 * @param {number} length - Value or length to encode
 */
function encodeHead(parts, majorType, length) {
  const mt = majorType << 5
  if (length < 24) {
    parts.push(mt | length)
  } else if (length < 256) {
    parts.push(mt | 24, length)
  } else if (length < 65536) {
    parts.push(mt | 25, length >> 8, length & 0xff)
  } else if (length < 4294967296) {
    // Use Math.floor instead of bitshift to avoid 32-bit signed integer overflow
    parts.push(mt | 26,
      Math.floor(length / 0x1000000) & 0xff,
      Math.floor(length / 0x10000) & 0xff,
      Math.floor(length / 0x100) & 0xff,
      length & 0xff)
  }
}
```

**Step 3: Update cborEncode to use shared helper**

Remove the local `encodeHead` function. Replace calls:
- `encodeHead(3, bytes.length)` → `encodeHead(parts, 3, bytes.length)`
- Same pattern for all other calls

**Step 4: Update cborEncodeDagCbor to use shared helper**

Remove the local `encodeHead` function. Update all calls to pass `parts` as first argument.

**Step 5: Update cborEncodeMstNode to use shared helper**

Remove the local `encodeHead` function. Update all calls to pass `parts` as first argument.

**Step 6: Run tests**

Run: `npm test`
Expected: All tests pass

**Step 7: Commit**

```bash
git add src/pds.js
git commit -m "refactor: consolidate CBOR encodeHead into shared helper"
```

---

## Task 3: Add JSDoc to Exported Functions

**Files:**
- Modify: `src/pds.js`

**Step 1: Add JSDoc to cborEncode**

```javascript
/**
 * Encode a value as CBOR bytes (RFC 8949 deterministic encoding)
 * @param {*} value - Value to encode (null, boolean, number, string, Uint8Array, array, or object)
 * @returns {Uint8Array} CBOR-encoded bytes
 */
export function cborEncode(value) {
```

**Step 2: Add JSDoc to cborDecode**

```javascript
/**
 * Decode CBOR bytes to a JavaScript value
 * @param {Uint8Array} bytes - CBOR-encoded bytes
 * @returns {*} Decoded value
 */
export function cborDecode(bytes) {
```

**Step 3: Add JSDoc to CID functions**

```javascript
/**
 * Create a CIDv1 (dag-cbor + sha-256) from raw bytes
 * @param {Uint8Array} bytes - Content to hash
 * @returns {Promise<Uint8Array>} CID bytes (36 bytes: version + codec + multihash)
 */
export async function createCid(bytes) {

/**
 * Convert CID bytes to base32lower string representation
 * @param {Uint8Array} cid - CID bytes
 * @returns {string} Base32lower-encoded CID with 'b' prefix
 */
export function cidToString(cid) {

/**
 * Encode bytes as base32lower string
 * @param {Uint8Array} bytes - Bytes to encode
 * @returns {string} Base32lower-encoded string
 */
export function base32Encode(bytes) {
```

**Step 4: Add JSDoc to TID function**

```javascript
/**
 * Generate a timestamp-based ID (TID) for record keys
 * Monotonic within a process, sortable by time
 * @returns {string} 13-character base32-sort encoded TID
 */
export function createTid() {
```

**Step 5: Add JSDoc to signing functions**

```javascript
/**
 * Import a raw P-256 private key for signing
 * @param {Uint8Array} privateKeyBytes - 32-byte raw private key
 * @returns {Promise<CryptoKey>} Web Crypto key handle
 */
export async function importPrivateKey(privateKeyBytes) {

/**
 * Sign data with ECDSA P-256, returning low-S normalized signature
 * @param {CryptoKey} privateKey - Web Crypto key from importPrivateKey
 * @param {Uint8Array} data - Data to sign
 * @returns {Promise<Uint8Array>} 64-byte signature (r || s)
 */
export async function sign(privateKey, data) {

/**
 * Generate a new P-256 key pair
 * @returns {Promise<{privateKey: Uint8Array, publicKey: Uint8Array}>} 32-byte private key, 33-byte compressed public key
 */
export async function generateKeyPair() {
```

**Step 6: Add JSDoc to utility functions**

```javascript
/**
 * Convert bytes to hexadecimal string
 * @param {Uint8Array} bytes - Bytes to convert
 * @returns {string} Hex string
 */
export function bytesToHex(bytes) {

/**
 * Convert hexadecimal string to bytes
 * @param {string} hex - Hex string
 * @returns {Uint8Array} Decoded bytes
 */
export function hexToBytes(hex) {

/**
 * Get MST tree depth for a key based on leading zeros in SHA-256 hash
 * @param {string} key - Record key (collection/rkey)
 * @returns {Promise<number>} Tree depth (leading zeros / 2)
 */
export async function getKeyDepth(key) {

/**
 * Encode integer as unsigned varint
 * @param {number} n - Non-negative integer
 * @returns {Uint8Array} Varint-encoded bytes
 */
export function varint(n) {

/**
 * Convert base32lower CID string to raw bytes
 * @param {string} cidStr - CID string with 'b' prefix
 * @returns {Uint8Array} CID bytes
 */
export function cidToBytes(cidStr) {

/**
 * Decode base32lower string to bytes
 * @param {string} str - Base32lower-encoded string
 * @returns {Uint8Array} Decoded bytes
 */
export function base32Decode(str) {

/**
 * Build a CAR (Content Addressable aRchive) file
 * @param {string} rootCid - Root CID string
 * @param {Array<{cid: string, data: Uint8Array}>} blocks - Blocks to include
 * @returns {Uint8Array} CAR file bytes
 */
export function buildCarFile(rootCid, blocks) {
```

**Step 7: Run tests**

Run: `npm test`
Expected: All tests pass (JSDoc doesn't affect runtime)

**Step 8: Commit**

```bash
git add src/pds.js
git commit -m "docs: add JSDoc to exported functions"
```

---

## Task 4: Add "Why" Comments to Protocol Logic

**Files:**
- Modify: `src/pds.js`

**Step 1: Add comment to DAG-CBOR key sorting**

In `cborEncodeDagCbor`, before the `keys.sort()` call:

```javascript
      // DAG-CBOR: sort keys by length first, then lexicographically
      // (differs from standard CBOR which sorts lexicographically only)
      const keys = Object.keys(val).filter(k => val[k] !== undefined)
      keys.sort((a, b) => {
```

**Step 2: Add comment to MST depth calculation**

In `getKeyDepth`, before the return:

```javascript
  // MST depth = leading zeros in SHA-256 hash / 2
  // This creates a probabilistic tree where ~50% of keys are at depth 0,
  // ~25% at depth 1, etc., giving O(log n) lookups
  const depth = Math.floor(zeros / 2)
```

**Step 3: Add comment to low-S normalization**

In `sign` function, before the if statement:

```javascript
  // Low-S normalization: Bitcoin/ATProto require S <= N/2 to prevent
  // signature malleability (two valid signatures for same message)
  if (sBigInt > P256_N_DIV_2) {
```

**Step 4: Add comment to CID tag encoding**

In `cborEncodeDagCbor`, at the CID encoding:

```javascript
    } else if (val instanceof CID) {
      // CID links in DAG-CBOR use tag 42 + 0x00 multibase prefix
      // The 0x00 prefix indicates "identity" multibase (raw bytes)
      parts.push(0xd8, CBOR_TAG_CID)
```

**Step 5: Run tests**

Run: `npm test`
Expected: All tests pass

**Step 6: Commit**

```bash
git add src/pds.js
git commit -m "docs: add 'why' comments to protocol-specific logic"
```

---

## Task 5: Extract PersonalDataServer Route Table

**Files:**
- Modify: `src/pds.js` (PERSONAL DATA SERVER section)

**Step 1: Define route table before class**

Add before `export class PersonalDataServer`:

```javascript
/**
 * Route handler function type
 * @callback RouteHandler
 * @param {PersonalDataServer} pds - PDS instance
 * @param {Request} request - HTTP request
 * @param {URL} url - Parsed URL
 * @returns {Promise<Response>} HTTP response
 */

/**
 * @typedef {Object} Route
 * @property {string} [method] - Required HTTP method (default: any)
 * @property {RouteHandler} handler - Handler function
 */

/** @type {Record<string, Route>} */
const pdsRoutes = {
  '/.well-known/atproto-did': {
    handler: (pds, req, url) => pds.handleAtprotoDid()
  },
  '/init': {
    method: 'POST',
    handler: (pds, req, url) => pds.handleInit(req)
  },
  '/status': {
    handler: (pds, req, url) => pds.handleStatus()
  },
  '/reset-repo': {
    handler: (pds, req, url) => pds.handleResetRepo()
  },
  '/forward-event': {
    handler: (pds, req, url) => pds.handleForwardEvent(req)
  },
  '/register-did': {
    handler: (pds, req, url) => pds.handleRegisterDid(req)
  },
  '/get-registered-dids': {
    handler: (pds, req, url) => pds.handleGetRegisteredDids()
  },
  '/repo-info': {
    handler: (pds, req, url) => pds.handleRepoInfo()
  },
  '/xrpc/com.atproto.server.describeServer': {
    handler: (pds, req, url) => pds.handleDescribeServer(req)
  },
  '/xrpc/com.atproto.sync.listRepos': {
    handler: (pds, req, url) => pds.handleListRepos()
  },
  '/xrpc/com.atproto.repo.createRecord': {
    method: 'POST',
    handler: (pds, req, url) => pds.handleCreateRecord(req)
  },
  '/xrpc/com.atproto.repo.getRecord': {
    handler: (pds, req, url) => pds.handleGetRecord(url)
  },
  '/xrpc/com.atproto.sync.getLatestCommit': {
    handler: (pds, req, url) => pds.handleGetLatestCommit()
  },
  '/xrpc/com.atproto.sync.getRepoStatus': {
    handler: (pds, req, url) => pds.handleGetRepoStatus()
  },
  '/xrpc/com.atproto.sync.getRepo': {
    handler: (pds, req, url) => pds.handleGetRepo()
  },
  '/xrpc/com.atproto.sync.subscribeRepos': {
    handler: (pds, req, url) => pds.handleSubscribeRepos(req, url)
  }
}
```

**Step 2: Extract handleAtprotoDid method**

Add to PersonalDataServer class:

```javascript
  async handleAtprotoDid() {
    let did = await this.getDid()
    if (!did) {
      const registeredDids = await this.state.storage.get('registeredDids') || []
      did = registeredDids[0]
    }
    if (!did) {
      return new Response('User not found', { status: 404 })
    }
    return new Response(did, { headers: { 'Content-Type': 'text/plain' } })
  }
```

**Step 3: Extract handleInit method**

```javascript
  async handleInit(request) {
    const body = await request.json()
    if (!body.did || !body.privateKey) {
      return Response.json({ error: 'missing did or privateKey' }, { status: 400 })
    }
    await this.initIdentity(body.did, body.privateKey, body.handle || null)
    return Response.json({ ok: true, did: body.did, handle: body.handle || null })
  }
```

**Step 4: Extract handleStatus method**

```javascript
  async handleStatus() {
    const did = await this.getDid()
    return Response.json({ initialized: !!did, did: did || null })
  }
```

**Step 5: Extract handleResetRepo method**

```javascript
  async handleResetRepo() {
    this.sql.exec(`DELETE FROM blocks`)
    this.sql.exec(`DELETE FROM records`)
    this.sql.exec(`DELETE FROM commits`)
    this.sql.exec(`DELETE FROM seq_events`)
    await this.state.storage.delete('head')
    await this.state.storage.delete('rev')
    return Response.json({ ok: true, message: 'repo data cleared' })
  }
```

**Step 6: Extract handleForwardEvent method**

```javascript
  async handleForwardEvent(request) {
    const evt = await request.json()
    const numSockets = [...this.state.getWebSockets()].length
    console.log(`forward-event: received event seq=${evt.seq}, ${numSockets} connected sockets`)
    this.broadcastEvent({
      seq: evt.seq,
      did: evt.did,
      commit_cid: evt.commit_cid,
      evt: new Uint8Array(Object.values(evt.evt))
    })
    return Response.json({ ok: true, sockets: numSockets })
  }
```

**Step 7: Extract handleRegisterDid method**

```javascript
  async handleRegisterDid(request) {
    const body = await request.json()
    const registeredDids = await this.state.storage.get('registeredDids') || []
    if (!registeredDids.includes(body.did)) {
      registeredDids.push(body.did)
      await this.state.storage.put('registeredDids', registeredDids)
    }
    return Response.json({ ok: true })
  }
```

**Step 8: Extract handleGetRegisteredDids method**

```javascript
  async handleGetRegisteredDids() {
    const registeredDids = await this.state.storage.get('registeredDids') || []
    return Response.json({ dids: registeredDids })
  }
```

**Step 9: Extract handleRepoInfo method**

```javascript
  async handleRepoInfo() {
    const head = await this.state.storage.get('head')
    const rev = await this.state.storage.get('rev')
    return Response.json({ head: head || null, rev: rev || null })
  }
```

**Step 10: Extract handleDescribeServer method**

```javascript
  handleDescribeServer(request) {
    const hostname = request.headers.get('x-hostname') || 'localhost'
    return Response.json({
      did: `did:web:${hostname}`,
      availableUserDomains: [`.${hostname}`],
      inviteCodeRequired: false,
      phoneVerificationRequired: false,
      links: {},
      contact: {}
    })
  }
```

**Step 11: Extract handleListRepos method**

```javascript
  async handleListRepos() {
    const registeredDids = await this.state.storage.get('registeredDids') || []
    const did = await this.getDid()
    const repos = did ? [{ did, head: null, rev: null }] :
      registeredDids.map(d => ({ did: d, head: null, rev: null }))
    return Response.json({ repos })
  }
```

**Step 12: Extract handleCreateRecord method**

```javascript
  async handleCreateRecord(request) {
    const body = await request.json()
    if (!body.collection || !body.record) {
      return Response.json({ error: 'missing collection or record' }, { status: 400 })
    }
    try {
      const result = await this.createRecord(body.collection, body.record, body.rkey)
      return Response.json(result)
    } catch (err) {
      return Response.json({ error: err.message }, { status: 500 })
    }
  }
```

**Step 13: Extract handleGetRecord method**

```javascript
  async handleGetRecord(url) {
    const collection = url.searchParams.get('collection')
    const rkey = url.searchParams.get('rkey')
    if (!collection || !rkey) {
      return Response.json({ error: 'missing collection or rkey' }, { status: 400 })
    }
    const did = await this.getDid()
    const uri = `at://${did}/${collection}/${rkey}`
    const rows = this.sql.exec(
      `SELECT cid, value FROM records WHERE uri = ?`, uri
    ).toArray()
    if (rows.length === 0) {
      return Response.json({ error: 'record not found' }, { status: 404 })
    }
    const row = rows[0]
    const value = cborDecode(new Uint8Array(row.value))
    return Response.json({ uri, cid: row.cid, value })
  }
```

**Step 14: Extract handleGetLatestCommit method**

```javascript
  handleGetLatestCommit() {
    const commits = this.sql.exec(
      `SELECT cid, rev FROM commits ORDER BY seq DESC LIMIT 1`
    ).toArray()
    if (commits.length === 0) {
      return Response.json({ error: 'RepoNotFound', message: 'repo not found' }, { status: 404 })
    }
    return Response.json({ cid: commits[0].cid, rev: commits[0].rev })
  }
```

**Step 15: Extract handleGetRepoStatus method**

```javascript
  async handleGetRepoStatus() {
    const did = await this.getDid()
    const commits = this.sql.exec(
      `SELECT cid, rev FROM commits ORDER BY seq DESC LIMIT 1`
    ).toArray()
    if (commits.length === 0 || !did) {
      return Response.json({ error: 'RepoNotFound', message: 'repo not found' }, { status: 404 })
    }
    return Response.json({ did, active: true, status: 'active', rev: commits[0].rev })
  }
```

**Step 16: Extract handleGetRepo method**

```javascript
  handleGetRepo() {
    const commits = this.sql.exec(
      `SELECT cid FROM commits ORDER BY seq DESC LIMIT 1`
    ).toArray()
    if (commits.length === 0) {
      return Response.json({ error: 'repo not found' }, { status: 404 })
    }
    const blocks = this.sql.exec(`SELECT cid, data FROM blocks`).toArray()
    const blocksForCar = blocks.map(b => ({
      cid: b.cid,
      data: new Uint8Array(b.data)
    }))
    const car = buildCarFile(commits[0].cid, blocksForCar)
    return new Response(car, {
      headers: { 'content-type': 'application/vnd.ipld.car' }
    })
  }
```

**Step 17: Extract handleSubscribeRepos method**

```javascript
  handleSubscribeRepos(request, url) {
    const upgradeHeader = request.headers.get('Upgrade')
    if (upgradeHeader !== 'websocket') {
      return new Response('expected websocket', { status: 426 })
    }
    const { 0: client, 1: server } = new WebSocketPair()
    this.state.acceptWebSocket(server)
    const cursor = url.searchParams.get('cursor')
    if (cursor) {
      const events = this.sql.exec(
        `SELECT * FROM seq_events WHERE seq > ? ORDER BY seq`,
        parseInt(cursor)
      ).toArray()
      for (const evt of events) {
        server.send(this.formatEvent(evt))
      }
    }
    return new Response(null, { status: 101, webSocket: client })
  }
```

**Step 18: Replace fetch method with router**

```javascript
  async fetch(request) {
    const url = new URL(request.url)
    const route = pdsRoutes[url.pathname]

    if (!route) {
      return Response.json({ error: 'not found' }, { status: 404 })
    }
    if (route.method && request.method !== route.method) {
      return Response.json({ error: 'method not allowed' }, { status: 405 })
    }
    return route.handler(this, request, url)
  }
```

**Step 19: Run tests**

Run: `npm test`
Expected: All tests pass

**Step 20: Commit**

```bash
git add src/pds.js
git commit -m "refactor: extract PersonalDataServer route table"
```

---

## Summary

After completing all tasks, the file will have:
- Named constants for CBOR markers and CID tag
- Single shared `encodeHead` helper (no duplication)
- JSDoc on all 15 exported functions
- "Why" comments on 4 protocol-specific code sections
- Declarative route table with 16 focused handler methods
- Same dependency order, same single file