Scanning for TODOs

The towl scan command walks a directory tree, reads each matching file, and extracts TODO-style comments using compiled regex patterns.

Interactive Mode (Default)

By default, towl scan opens an interactive TUI:

towl scan
towl scan src/

See Interactive TUI for details on the TUI interface.

Non-Interactive Mode

Use --non-interactive / -N to disable the TUI (for CI/scripting):

towl scan -N
towl scan -N src/
towl scan -N -v

How Scanning Works

1. Directory walk -- Uses the ignore crate to traverse the file tree, respecting .gitignore rules automatically
2. Extension filter -- Only files matching file_extensions in config are read (default: rs, toml, json, yaml, yml, sh, bash)
3. Exclude patterns -- Files matching exclude_patterns are skipped (default: target/*, .git/*)
4. Concurrent scanning -- Matching files are scanned concurrently with bounded parallelism (up to 64 files at once)
5. Content parsing -- Each file is read and scanned for lines matching comment_prefixes, then checked against todo_patterns
6. Context extraction -- Surrounding lines and enclosing function names are captured

Verbose Mode

The -v / --verbose flag prints scan metrics to stderr (non-interactive mode only):

towl scan -N -v

Files scanned: 42
Files skipped: 3
Files errored: 0
Scan duration: 12ms

Filtering by Type

Restrict results to a single TODO type:

towl scan -N -t todo      # Only TODO comments
towl scan -N -t fixme     # Only FIXME comments
towl scan -N -t hack      # Only HACK comments
towl scan -N -t note      # Only NOTE comments
towl scan -N -t bug       # Only BUG comments

The filter value is case-insensitive on the command line but stored lowercase internally.

GitHub Issue Creation

Create GitHub issues from found TODOs:

# Create issues
towl scan -N -g

# Preview without creating
towl scan -N -g -n

When issues are created, towl automatically replaces the TODO comment in source files with a link to the created issue. Duplicate detection prevents creating issues for TODOs that already have a matching open issue.

In interactive mode, select TODOs with Space and press Enter to create issues.

AI Analysis

Use the --ai flag to validate TODOs with an LLM:

# Analyse and filter out invalid TODOs
towl scan -N --ai

# Interactive mode with AI analysis
towl scan --ai

# Create GitHub issues for valid TODOs only (enriched with AI reasoning)
towl scan -N --ai -g

In non-interactive mode, TODOs classified as Invalid are automatically excluded from the output. See AI Analysis for full details.

Combining Options

Options compose freely:

# Scan src/, output FIXME comments as JSON to a file, verbose
towl scan -N src/ -t fixme -f json -o fixmes.json -v

# Scan and create GitHub issues for TODO comments only
towl scan -N -t todo -g

# AI-validated FIXMEs as JSON
towl scan -N --ai -t fixme -f json -o fixmes.json

Resource Limits

towl enforces hard limits to prevent runaway scans:

When a limit is hit, scanning stops gracefully and returns the results collected so far.

Scan Result

The scan produces a ScanResult containing:

• todos -- The list of extracted TodoComment items
• files_scanned -- Number of files successfully read
• files_skipped -- Number of files skipped (wrong extension, excluded, too large)
• files_errored -- Number of files that failed to read (permissions, encoding)
• duration -- Wall-clock time for the scan

Two convenience checks:

• all_files_failed() -- Returns true when no files were scanned but errors occurred (likely a permissions or path issue)
• is_clean() -- Returns true when zero TODOs were found and zero files errored

Path Safety

• Path traversal -- Paths containing .. components are rejected
• Symlink resolution -- Symlinks are resolved before processing to prevent escape from the scan root
• .gitignore -- Respected automatically via the ignore crate