# Architecture
## Overview
RSMultiGit follows a simple pipeline: **discover projects** → **run command** → **collect results**.
## Module structure
```
src/
main.rs Entry point, CLI dispatch
cli.rs Clap derive definitions (Cli + Commands)
config.rs AppConfig runtime struct
discovery.rs Project discovery via glob or folder list
runner.rs Three execution patterns
subprocess_utils.rs Shell command helpers
commands/
mod.rs Module declarations
count.rs git2-based repo inspection (dirty, untracked, synchronized)
status.rs git status / diff via subprocess
branch.rs Branch listing (local, remote, github)
pull.rs git pull
clean.rs git clean -ffxd
diff.rs git diff
grep.rs git grep with project-name prefix
build.rs Build commands (make, pydmt, rsbuild, bootstrap)
```
## Runner patterns
All subcommands use one of three runner functions:
### `do_count`
For count commands (`count-dirty`, `untracked`, `synchronized`). Calls a test function on each project path (using libgit2, no subprocess), counts matches, optionally prints statistics.
### `do_for_all_projects`
For action commands (`pull`, `clean-hard`, `diff`, `grep`, `branch-*`, `build-*`). Changes into each project directory, runs the action, prints a header. Respects `--no-stop` for error handling.
### `print_if_data`
For status commands (`status`, `dirty`, `list-projects`). Changes into each project directory, calls a data function. If it returns `Some(text)`, prints the project name and data. If `None`, the project is silently skipped.
## Git inspection
The count commands (`count-dirty`, `untracked`, `synchronized`) use the `git2` crate for direct repository inspection. This avoids forking `git` subprocesses and is significantly faster for large numbers of repos.
All other git operations use `std::process::Command` to run the `git` CLI, which provides familiar output formatting and handles edge cases that libgit2 may not cover.
## Error handling
All functions return `anyhow::Result`. The `--no-stop` flag controls whether errors in individual projects are fatal (default) or logged and skipped.
## Build script
The `build.rs` script embeds git metadata (commit SHA, branch, dirty status, describe) and the Rust compiler version at compile time. These are accessible via `env!()` macros and displayed by `rsmultigit version`.