Add script that generates release notes and info

.gitignore

@@ -96,4 +96,7 @@ lint/tmp/
 # OSX
 .DS_Store
 
-.kotlin
+.kotlin
+
+# Release notes generator output
+gen-rn/output/

gen-rn/README.md

@@ -0,0 +1,142 @@
+# gen-rn: XMTP SDK release notes generator
+
+AI-powered release notes generation for XMTP SDK releases using git history analysis and Claude AI.
+
+> [!IMPORTANT]
+> Generated release notes must be reviewed by humans before publication. The AI provides a starting point, not a final product.
+
+## Purpose
+
+1. **Engineering sanity check**: Help engineers understand exactly what's included in a release
+2. **Technical writing support**: Help technical writers with structured, well-organized release content  
+3. **Cross-SDK consistency**: Run in each XMTP SDK repo and compare structured outputs to gauge consistency of feature and fix implementations across SDKs
+
+## Prerequisites
+
+- Node.js 18 or later (required for native fetch API support)
+- Anthropic API key: Get a key at: [https://console.anthropic.com/](https://console.anthropic.com/)
+
+## Configuration
+
+The script supports the following environment variables:
+
+- `ANTHROPIC_API_KEY` (required): Your Anthropic API key for Claude AI
+- `MAX_TOKENS` (optional): Maximum tokens for AI response (default: 4000, range: 1000-8000)
+
+### API key handling
+
+- Never commit your `ANTHROPIC_API_KEY` to version control
+- Store your API key in your shell profile as described in Setup
+- Rotate your API key immediately if it's accidentally exposed or committed
+- The temporary `ai-script.js` file is automatically deleted after execution for security
+
+## Setup
+
+```bash
+# Set your API key
+export ANTHROPIC_API_KEY="sk-ant-your-key-here"
+echo 'export ANTHROPIC_API_KEY="your-key"' >> ~/.zshrc
+source ~/.zshrc
+
+# Fetch latest tags
+git fetch --tags
+
+# Make script executable  
+chmod +x gen-rn.sh
+
+# Optionally, set custom token limit for current terminal session
+export MAX_TOKENS=6000
+```
+
+## Usage
+
+### Basic usage
+
+```bash
+# Auto-detect previous tag and generate delta
+./gen-rn.sh 4.6.4
+
+# Specify both tags to compare (what's new in 4.6.4 vs 4.6.3)
+./gen-rn.sh 4.6.4 4.6.3
+
+# Interactive mode - prompts for tag selection
+# Detects previous tag and generate delta
+./gen-rn.sh
+
+# Help
+./gen-rn.sh --help
+```
+
+### Custom base comparison with `--from-base`
+
+Use the `--from-base` flag to compare a release against any git reference (branch, tag, or commit):
+
+```bash
+# Show everything in 4.6.4 that's not in main
+./gen-rn.sh 4.6.4 --from-base main
+
+# Show full content of a release candidate
+./gen-rn.sh 4.6.4-rc.1 --from-base main
+
+# Show all changes since a specific older tag
+./gen-rn.sh 4.6.4 --from-base 4.5.0
+
+# Compare against a branch
+./gen-rn.sh 4.6.4 --from-base release/4.6
+```
+
+### Supported release types
+
+The script automatically detects release types based on tag naming:
+
+```bash
+# Stable release (production-ready)
+./gen-rn.sh 4.6.7                    # → Release type: stable
+
+# Release candidate (pre-release testing)
+./gen-rn.sh 4.6.7-rc.1 4.6.6         # → Release type: release-candidate
+
+# Development release (experimental)
+./gen-rn.sh 4.6.7-dev.abc123 4.6.7   # → Release type: development
+```
+
+### Tag name validation
+
+The script validates all tag names to prevent command injection attacks. Tag names must contain only:
+- Letters (a-z, A-Z)
+- Numbers (0-9)
+- Dots (.)
+- Hyphens (-)
+- Underscores (_)
+- Forward slashes (/)
+
+## Output files
+
+After running, check the `output/` directory:
+
+```text
+output/
+├── release-notes.md    # Main AI-generated release notes
+├── release-data.txt    # Raw git analysis data (for debugging)
+└── pr-refs.txt         # PR numbers found in commits
+```
+
+> [!NOTE]
+> - The `gen-rn/output/` directory is automatically excluded from version control via `.gitignore`
+> - The temporary `ai-script.js` file is automatically deleted after execution for security
+
+## Troubleshooting
+
+### "Not in a git repository"
+
+- Run from the root of your XMTP SDK repository
+
+### "ANTHROPIC_API_KEY not set"
+
+- Set your API key: `export ANTHROPIC_API_KEY="your-key"`
+- Get a key at: https://console.anthropic.com/
+
+### "Could not compare tags"
+
+- Verify both tags exist: `git tag | grep 4.6.4`  
+- Use explicit tag names: `./gen-rn.sh 4.6.4 4.6.3`