Remove Node.js hooks, require ots CLI only

- Delete hooks/post-commit-node (local proofs only, no attestation)
- Delete hooks/pre-commit-node (no upgrade support)
- Update hooks/install.sh to require ots CLI (no fallback)
- Update documentation with clear ots CLI requirement
- Add prominent warnings about Node.js limitations

Rationale: The @opentimestamps/ots Node.js package only creates
local proofs without calendar submission or Bitcoin attestation.
For tamper-evident timestamps, ots CLI is the only complete
implementation. No partial/fallback implementations.

README.md

@@ -1,24 +1,25 @@
 # Git OpenTimestamp Hook
 
-Automatically generate and manage [OpenTimestamp](https://opentimestamps.org/) proofs for git commits.
+Automatically generate [OpenTimestamp](https://opentimestamps.org/) proofs for git commits with full Bitcoin attestation.
 
-## What It Does
+## ⚠️ Requirements
 
-- **Post-commit hook**: Creates cryptographic proof for every commit
-- **Pre-commit backfill**: Upgrades historical proofs to Bitcoin-attested status
-- **Proof chaining**: Links commits together for full history integrity
-- **Smart caching**: Minimizes network calls after initial backfill
+**Required:** `opentimestamps-client` (ots CLI)
 
-Proofs are stored in `.ots/` and can be versioned alongside your code for tamper-evident history.
+```bash
+pipx install opentimestamps-client
+```
+
+> **Note:** The Node.js `@opentimestamps/ots` package is **not supported** - it only creates local proofs without calendar submission or Bitcoin attestation. For tamper-evident timestamps, you must use the Python `opentimestamps-client`.
 
 ## Quick Install
 
 ```bash
-# Clone or download this skill
+# Clone this repository
 git clone <repository-url>
 cd git-ots-hook
 
-# Install both hooks (auto-detects ots CLI or Node.js)
+# Install hooks (requires ots CLI)
 ./hooks/install.sh /path/to/your/repo
 
 # Commit the proofs
@@ -27,102 +28,85 @@ git add .ots/
 git commit -m "Add OpenTimestamp proofs"
 ```
 
-That's it! The hooks are now installed and will automatically timestamp every commit.
+That's it! Every commit will now be timestamped and anchored to Bitcoin.
 
 ## Manual Installation
 
-### For ots CLI (Recommended)
-
 ```bash
+# Copy hooks
 cp hooks/post-commit-ots .git/hooks/post-commit
 cp hooks/pre-commit-ots .git/hooks/pre-commit
 chmod +x .git/hooks/post-commit .git/hooks/pre-commit
+
+# Setup .gitignore
+echo ".ots/.attestation-cache" >> .gitignore
 ```
 
-### For Node.js (Local proofs only)
+## What You Get
 
-```bash
-cp hooks/post-commit-node .git/hooks/post-commit
-cp hooks/pre-commit-node .git/hooks/pre-commit
-chmod +x .git/hooks/post-commit .git/hooks/pre-commit
-```
-
-### Setup .gitignore
-
-```
-.ots/.attestation-cache
-node_modules/
-```
-
-### Commit Initial Proofs
-
-```bash
-git add .ots/
-git commit -m "Add OpenTimestamp proofs"
-```
-
-## Prerequisites
-
-Install the OpenTimestamp client:
-
-```bash
-# Recommended: Python CLI
-pipx install opentimestamps-client
-
-# Alternative: Node.js package
-npm install -g @opentimestamps/ots
-```
-
-Verify installation:
-```bash
-ots --version
-```
+- **Automatic timestamping** - Every commit gets a cryptographic proof
+- **Bitcoin attestation** - Proofs anchored to Bitcoin blockchain (~10 min)
+- **Full history** - Backfill hook upgrades all historical commits
+- **Smart caching** - Minimal network overhead after initial setup
+- **Tamper-evident** - Anyone can verify your commit history
 
 ## Generated Files
 
 ```
 repo/
 ├── .ots/
-│   ├── <commit-hash>.ots    # Individual proof per commit
-│   ├── proof.ots            # Latest commit proof
-│   ├── prev-commit.txt      # Previous commit reference
-│   ├── commit-chain.txt     # Full commit chain
-│   └── .attestation-cache   # Local cache (gitignore this)
+│   ├── <commit-hash>.ots   # Individual proof (commit this)
+│   ├── proof.ots           # Latest proof (commit this)
+│   ├── prev-commit.txt     # Chain link (commit this)
+│   ├── commit-chain.txt    # Full chain (commit this)
+│   └── .attestation-cache  # Local cache (ignore this)
 └── ...
 ```
 
 ## Verification
 
-Verify a proof:
+**Check a proof:**
+```bash
+ots info .ots/<commit-hash>.ots
+```
+
+**Verify attestation:**
 ```bash
 ots verify .ots/<commit-hash>.ots
 ```
 
-Check attestation status:
+**Upgrade pending proofs:**
 ```bash
-./scripts/check-attestation.sh .ots/<commit-hash>.ots
-# Output: "attested" or "pending"
+ots upgrade .ots/<commit-hash>.ots
 ```
 
 ## How It Works
 
-1. **Commit created** → Post-commit hook runs
-2. **Proof generated** → `ots stamp` creates `.ots` file
-3. **Submitted to calendars** → 4+ remote calendars receive hash
-4. **Bitcoin anchoring** → Calendars batch and anchor to Bitcoin (~10 min)
-5. **Attestation** → Proof becomes fully verifiable against Bitcoin blockchain
+1. You make a git commit
+2. Post-commit hook extracts commit hash
+3. Hash submitted to 4+ remote calendar servers
+4. Calendars aggregate and anchor to Bitcoin
+5. After ~10 min: proof becomes Bitcoin-attested
+6. Pre-commit hook upgrades old proofs before new commits
 
 ## Performance
 
-- **First backfill**: 30-60s (scans history, contacts calendars)
-- **Subsequent commits**: 10-15s (cached status skips redundant calls)
-- **Cache**: 1-hour validity, 10-min recheck for pending proofs
+- **First backfill:** 30-60s (full history scan)
+- **Normal commits:** 10-15s (cached, minimal network)
+- **Attestation:** ~10 min (Bitcoin block time)
 
-## License
+## Uninstall
 
-MIT
+```bash
+rm .git/hooks/post-commit .git/hooks/pre-commit
+```
 
 ## Links
 
 - [OpenTimestamp](https://opentimestamps.org/)
-- [ots Client](https://github.com/opentimestamps/opentimestamps-client)
+- [opentimestamps-client](https://github.com/opentimestamps/opentimestamps-client)
+- [Bitcoin anchoring explained](https://petertodd.org/2016/opentimestamps-announcement)
+
+## License
+
+MIT