Function take_snapshot

atomic-agent/src/watcher/fallback.rs:70–122

Walk the directory tree and build a snapshot of all files. Skips directories matching any of the ignore patterns. Only includes regular files (not directories, symlinks, etc.).

(repo_root: &Path, ignore_patterns: &[String])

/// Skips directories matching any of the ignore patterns.
/// Only includes regular files (not directories, symlinks, etc.).
fn take_snapshot(repo_root: &Path, ignore_patterns: &[String]) -> AgentResult<FileSnapshot> {
    let mut snapshot = HashMap::new();

    let walker = WalkDir::new(repo_root)
        .follow_links(false)
        .into_iter()
        .filter_entry(|entry| {
            // Skip ignored directories
            if entry.file_type().is_dir() {
                let name = entry.file_name().to_string_lossy();
                for pattern in ignore_patterns {
                    if name == pattern.as_str() {
                        return false;
                    }
                }
                // Also skip common VCS/build directories for performance
                if matches!(
                    name.as_ref(),
                    ".git" | "node_modules" | "target" | "__pycache__" | ".DS_Store"
                ) {
                    return false;
                }
            }
            true
        });

    for entry in walker {
        let entry = entry.map_err(|e| AgentError::Internal(format!("walkdir error: {}", e)))?;

        // Only track regular files
        if !entry.file_type().is_file() {
            continue;
        }

        let path = entry.path();

        // Get metadata for mtime and size
        let metadata = match entry.metadata() {
            Ok(m) => m,
            Err(_) => continue, // Skip files we can't stat (permissions, etc.)
        };

        let mtime = metadata.modified().unwrap_or(SystemTime::UNIX_EPOCH);
        let size = metadata.len();

        // Store path relative to repo root
        if let Ok(relative) = path.strip_prefix(repo_root) {
            snapshot.insert(relative.to_path_buf(), FileEntry { mtime, size });
        }
    }

    Ok(snapshot)
}

/// Diff two snapshots to produce a `TurnChanges`.
fn diff_snapshots(before: &FileSnapshot, after: &FileSnapshot) -> TurnChanges {