fast-gate

Deterministic pre-flight facts for Fact-Forcing Gate (GateGuard-style) hooks.

Hooks like GateGuard reject a Write or Update unless the agent first states: who calls the file, that nothing already serves the same purpose, the schema of any data it touches, and the user's instruction verbatim. fast-gate computes the first three from the workspace and formats all four, so the agent does not have to research or reformat them by hand.

Install

uv pip install -e .        # or: pip install -e .

The package is published as fast-gate-py; the command is fast-gate. Python 3.10+.

Use

# print the four-point block for a file you are about to write
fast-gate inspect src/app/export.py --instruction "Add a CSV exporter to app" --root .

# exit 0 if the target is safe to write, 1 (with reasons on stderr) otherwise
fast-gate check src/app/export.py

Relative targets are resolved from the current directory; --root (default .) is the workspace to scan.

Example output:

## Pre-flight facts for `src/app/export.py` (create new file)

### 1. Callers / importers

- No existing file imports or references the target.
- Planned caller / entry point: `src/app/cli.py` (console script `app = app.cli:main`) is expected to import or dispatch to it

### 2. Non-duplication

- Searched 14 file(s) under the workspace root (skipped: .git, .venv, venv, __pycache__, ...).
- No file has the same name, the same stem, or a similar name; nothing existing serves this purpose.

### 3. Data schemas

- N/A: the target does not exist yet and the instruction names no data file; ...

### 4. Verbatim user instruction

> Add a CSV exporter to app

What it checks

Workspace text (paths, field names, source lines) is stripped of backticks and control characters before it is put in the block, so a hostile CSV header cannot forge a heading.

Claude Code integration

• skills/fast-gate.md: the skill. Copy it to ~/.claude/skills/fast-gate/SKILL.md (or a project's .claude/skills/) to have Claude run fast-gate inspect before guarded writes.
• .claude/commands/fast-gate.md: the /fast-gate <target_file> slash command for this repo.

Some hooks deny the first attempt on every new file no matter what was presented, then accept an identical retry. fast-gate cannot change that behavior; it makes the facts correct and complete so the retry is a single call.

Development

./venv/bin/pytest tests/ -v
ruff check .