# AT Protocol PLC Command-Line Tools

Command-line tools for working with AT Protocol PLC (Public Ledger of Credentials) DIDs.

## Tools

### plc-audit: DID Audit Log Validator

Validates the cryptographic integrity of a DID's audit log from plc.directory.

#### Features

- 🔍 **Fetch Audit Logs**: Retrieves complete operation history from plc.directory
- 🔐 **Cryptographic Validation**: Verifies all signatures using rotation keys
- 🔗 **Chain Verification**: Validates operation chain linkage (prev references)
- 📊 **Detailed Output**: Shows operation history and final DID state
- ⚡ **Fast & Reliable**: Built with Rust for performance and safety

#### Usage

```bash
# Basic validation
cargo run --bin plc-audit --features cli -- did:plc:z72i7hdynmk6r22z27h6tvur

# Verbose mode (show all operations)
cargo run --bin plc-audit --features cli -- did:plc:z72i7hdynmk6r22z27h6tvur --verbose

# Quiet mode (VALID/INVALID only)
cargo run --bin plc-audit --features cli -- did:plc:z72i7hdynmk6r22z27h6tvur --quiet

# Custom PLC directory
cargo run --bin plc-audit --features cli -- did:plc:example --plc-url https://custom.plc.directory
```

---

### plc-fork-viz: Fork Visualizer

Visualizes forks in a DID's operation chain, showing which operations won/lost based on rotation key priority and the 72-hour recovery window.

#### Features

- 🔀 **Fork Detection**: Identifies competing operations in the chain
- 🔐 **Priority Analysis**: Determines which rotation key signed each operation
- ⏱️ **Recovery Window**: Applies 72-hour recovery window rules
- 📊 **Multiple Formats**: Tree, JSON, and Markdown visualization
- 🎨 **Color Coding**: Green for canonical operations, red for rejected

#### Usage

```bash
# Basic fork visualization
cargo run --bin plc-fork-viz --features cli -- did:plc:ewvi7nxzyoun6zhxrhs64oiz

# Verbose mode (detailed operation info)
cargo run --bin plc-fork-viz --features cli -- did:plc:ewvi7nxzyoun6zhxrhs64oiz --verbose

# Show timestamps and recovery window calculations
cargo run --bin plc-fork-viz --features cli -- did:plc:ewvi7nxzyoun6zhxrhs64oiz --timing

# Show full DIDs/CIDs
cargo run --bin plc-fork-viz --features cli -- did:plc:ewvi7nxzyoun6zhxrhs64oiz --full-ids

# Output as JSON
cargo run --bin plc-fork-viz --features cli -- did:plc:ewvi7nxzyoun6zhxrhs64oiz --format json

# Output as Markdown
cargo run --bin plc-fork-viz --features cli -- did:plc:ewvi7nxzyoun6zhxrhs64oiz --format markdown
```

#### Output Formats

**Tree Format** (default):
```
Fork at operation referencing bafyre...abc123
  ├─ 🔴 ✗ CID: bafyre...def456
  │  Signed by: rotation_key[1]
  │  Reason: Invalidated by higher-priority key[0] within recovery window
  └─ 🟢 ✓ CID: bafyre...ghi789
     Signed by: rotation_key[0]
     Status: CANONICAL (winner)
```

**JSON Format**:
```json
[
  {
    "prev_cid": "bafyre...",
    "winner_cid": "bafyre...",
    "operations": [...]
  }
]
```

**Markdown Format**:
| Status | CID | Key Index | Timestamp | Reason |
|--------|-----|-----------|-----------|--------|
| ✅ Winner | bafyre...ghi789 | 0 | 2025-01-15 14:30:00 | Canonical operation |
| ❌ Rejected | bafyre...def456 | 1 | 2025-01-15 10:00:00 | Invalidated by higher-priority key[0] |

#### Fork Resolution Rules

1. **Rotation Key Priority**: Keys are ordered by array index (0 = highest priority)
2. **Recovery Window**: 72 hours from the first operation's timestamp
3. **First-Received Default**: The operation received first wins unless invalidated
4. **Higher Priority Override**: A higher-priority key can invalidate if:
   - It arrives within 72 hours
   - Its key index is lower (e.g., key[0] beats key[1])

#### Example: No Forks

```bash
$ cargo run --bin plc-fork-viz --features cli -- did:plc:ewvi7nxzyoun6zhxrhs64oiz

🔍 Analyzing forks in: did:plc:ewvi7nxzyoun6zhxrhs64oiz
   Source: https://plc.directory

📊 Audit log contains 5 operations

✅ No forks detected - this is a linear operation chain
   All operations form a single canonical path from genesis to tip.
```

#### Example: Fork Detected

```bash
$ cargo run --bin plc-fork-viz --features cli -- did:plc:z7x2k3j4m5n6 --timing

🔍 Analyzing forks in: did:plc:z7x2k3j4m5n6
   Source: https://plc.directory

📊 Audit log contains 8 operations
⚠️  Detected 1 fork point(s)

📊 Fork Visualization (Tree Format)
═══════════════════════════════════════════════════════════════

Fork at operation referencing bafyre...abc123
  ├─ 🔴 ✗ CID: bafyre...def456
     │  Signed by: rotation_key[1]
     │  Timestamp: 2025-01-15 10:00:00 UTC
     │  Reason: Invalidated by higher-priority key[0] within recovery window
     │
  └─ 🟢 ✓ CID: bafyre...ghi789
     │  Signed by: rotation_key[0]
     │  Timestamp: 2025-01-15 14:00:00 UTC
     │  Status: CANONICAL (winner)

═══════════════════════════════════════════════════════════════
📈 Summary:
   Total operations: 8
   Fork points: 1
   Rejected operations: 1

🔐 Fork Resolution Details:
   Fork 1: Winner is bafyre...ghi789 (signed by key[0])
```

---

## Building & Installation

### Build Both Tools

```bash
cargo build --bins --features cli --release
```

### Install to ~/.cargo/bin

```bash
cargo install --path . --features cli
```

Then use directly:
```bash
plc-audit did:plc:ewvi7nxzyoun6zhxrhs64oiz
plc-fork-viz did:plc:ewvi7nxzyoun6zhxrhs64oiz
```

---

## Common Workflows

### Workflow 1: Validate and Check for Forks

```bash
# First validate the audit log
$ plc-audit did:plc:ewvi7nxzyoun6zhxrhs64oiz
✅ Validation successful!

# Then check for forks
$ plc-fork-viz did:plc:ewvi7nxzyoun6zhxrhs64oiz
```

### Workflow 2: Export Fork Data

```bash
# Export as JSON for analysis
$ plc-fork-viz did:plc:ewvi7nxzyoun6zhxrhs64oiz --format json > forks.json

# Generate Markdown report
$ plc-fork-viz did:plc:ewvi7nxzyoun6zhxrhs64oiz --format markdown > FORK_REPORT.md
```

### Workflow 3: Monitor DIDs

```bash
#!/bin/bash
# Monitor a DID for changes and forks
DID="did:plc:ewvi7nxzyoun6zhxrhs64oiz"

# Validate
if plc-audit $DID --quiet; then
  echo "✅ DID is valid"

  # Check for forks
  plc-fork-viz $DID --format json > /tmp/forks.json

  if [ -s /tmp/forks.json ]; then
    echo "⚠️ Forks detected!"
    plc-fork-viz $DID
  fi
else
  echo "❌ DID validation failed!"
  exit 1
fi
```

---

## Understanding Fork Visualization

### Symbols

- 🌱 Genesis operation (creates the DID)
- 🟢 ✓ Canonical operation (winner)
- 🔴 ✗ Rejected operation (lost the fork)
- ├─ Fork branch (more operations follow)
- └─ Final fork branch

### Rejection Reasons

1. **"Invalidated by higher-priority key[N] within recovery window"**
   - A higher-priority rotation key signed a competing operation within 72 hours

2. **"Higher-priority key[N] but outside 72-hour recovery window (X hours late)"**
   - A higher-priority key tried to invalidate but arrived too late

3. **"Lower-priority key[N] (current winner has key[M])"**
   - This operation was signed by a lower-priority key and can't override

---

## Troubleshooting

### Error: "Invalid DID format"
DID must follow format: `did:plc:<24 lowercase base32 characters>`

### Error: "Failed to fetch audit log"
- Check internet connection
- Verify DID exists on plc.directory
- Try `--plc-url` for custom PLC directories

### No forks detected but expected
- The DID may have a linear operation chain
- All operations were submitted sequentially without conflicts

---

## Technical Details

**plc-audit** validates:
1. DID format (prefix, length, base32 encoding)
2. Chain linkage (prev references)
3. Cryptographic signatures (ECDSA with P-256/secp256k1)
4. State consistency

**plc-fork-viz** implements:
1. Fork detection (multiple operations with same prev CID)
2. Rotation key index resolution
3. Priority-based fork resolution
4. 72-hour recovery window enforcement

Both tools use:
- `reqwest` for HTTP requests
- `atproto-plc` library for cryptographic operations
- `clap` for command-line parsing

---

## See Also

- [AT Protocol PLC Specification](https://atproto.com/specs/did-plc)
- [Fork Resolution Implementation Report](../../FORK_RESOLUTION_REPORT.md)
- [Implementation Summary](../../IMPLEMENTATION_SUMMARY.md)
- [Library Documentation](../../README.md)

---

## License

Dual-licensed under MIT or Apache-2.0, same as the parent library.