Use XDG config directory as default config path

- Look for config at $XDG_CONFIG_HOME/converge/config.yaml by default
- --config still overrides to an explicit path
- Falls back to single-repo --repo mode if no config file found
- New defaultConfigPath and configFileExists helpers in Converge module

README.md

@@ -6,41 +6,47 @@ Converge notifies the user via libnotify / `notify-send` whenever a merge confli
 
 ## Usage
 
-### Single repository
+### Configuration
+
+Converge looks for its config file at `$XDG_CONFIG_HOME/converge/config.yaml` (typically `~/.config/converge/config.yaml`). If found, it uses that file automatically.
 
 ```bash
-# Watch the current directory (defaults)
+# Run with the default XDG config file
 ./scripts/run
-
-# Watch a specific repo
-./scripts/run -- --repo /path/to/repo --branch master --debounce 10000
 ```
 
-### Multiple repositories (config file)
+You can also specify a config file explicitly:
 
 ```bash
-# Create a config file
-cp converge.example.yaml converge.yaml
-# Edit to list your repos
-vim converge.yaml
+./scripts/run -- --config /path/to/converge.yaml
+```
 
-# Run with config
-./scripts/run -- --config converge.yaml
+### Single repository (no config file)
+
+If no config file exists, converge falls back to watching a single repository:
+
+```bash
+# Watch the current directory
+./scripts/run
+
+# Watch a specific repo with options
+./scripts/run -- --repo /path/to/repo --branch master --debounce 10000
 ```
 
 ### Options
 
 | Option | Default | Description |
 |--------|---------|-------------|
-| `-c`, `--config FILE` | — | Path to YAML config file listing repositories |
-| `-r`, `--repo PATH` | `.` (cwd) | Path to a single git repository |
-| `-d`, `--debounce MS` | `5000` | Debounce window in milliseconds (overrides config) |
-| `--remote NAME` | `origin` | Remote name (single-repo mode) |
-| `-b`, `--branch NAME` | `main` | Branch to pull (single-repo mode) |
+| `-c`, `--config FILE` | `$XDG_CONFIG_HOME/converge/config.yaml` | Path to YAML config file listing repositories |
+| `-r`, `--repo PATH` | `.` (cwd) | Path to a single git repository (single-repo fallback mode) |
+| `-d`, `--debounce MS` | `5000` | Debounce window in milliseconds (overrides config file) |
+| `--remote NAME` | `origin` | Remote name (single-repo fallback mode) |
+| `-b`, `--branch NAME` | `main` | Branch to pull (single-repo fallback mode) |
 
 ### Config file format
 
 ```yaml
+# ~/.config/converge/config.yaml  (XDG default)
 repos:
   - path: /absolute/or/relative/path
     remote: origin    # optional, defaults to "origin"
@@ -74,5 +80,5 @@ All development tools run inside Docker via the `hs` wrapper script.
 - **File watching**: [fsnotify](https://hackage.haskell.org/package/fsnotify)
 - **Concurrency**: one watcher thread per repository via `async`
 - **Notifications**: shell out to `notify-send` (libnotify)
-- **Configuration**: YAML config file for multi-repo, CLI flags for single-repo
+- **Configuration**: YAML config file at XDG config path for multi-repo, CLI flags for single-repo fallback
 - **Daemonization**: TBD (likely systemd service)