# llmlint
**The next generation of linting: an LLM as a judge.** `llmlint` enforces the
code-quality checks a human reviewer normally makes — adherence to architectural
patterns, coding-style intent, alignment to organization objectives — that
deterministic linters can't express. It is **additive** to your existing linters,
not a replacement: keep using deterministic tools for everything they can already
check, and reach for llmlint only for the judgment calls.
Each check is a **rule**: a statement about your code that is judged `true`
(holds) or `false` (a violation). llmlint batches your rules, drives a real coding
harness (Claude Code, Codex, Cursor, …) through
[`oneharness`](https://github.com/nickderobertis/oneharness) to read the relevant
files and decide, and reports the violations — with file and line numbers where
they can be pinned down. Because the gate is "just a config file," llmlint drops
into CI next to your other linters.
```console
$ llmlint
FAIL handlers_delegate_to_services (2/3 judges held)
src/api/users.rs:48: user creation logic lives in the handler, not a service
PASS modules_have_doc_comments
SKIP no_todo_without_ticket (no files matched)
3 rules: 1 passed, 1 failed, 1 skipped
```
## How it works
1. You declare **rules** (and optionally **agents** that group them) in a YAML
config — like any other linter.
2. For each agent, llmlint renders a system prompt from a template (the rules +
the target file paths) and calls `oneharness run` with a generated **JSON
Schema** for structured output. oneharness constrains and validates the
harness's answer, so llmlint gets a checked verdict per rule, not prose.
3. The harness reads the target files on demand with its own tools to gather
evidence, then returns `{ "rule_name": { "holds": bool, "violations": [...] } }`.
4. llmlint aggregates (majority vote across judges when configured), reports, and
exits non-zero if any rule was violated.
llmlint **shells out to oneharness** — it is a runtime prerequisite (see Install).
## Install
`llmlint` needs the `oneharness` binary on your `PATH`.
```console
# 1) oneharness (the harness driver)
# 2) llmlint
# (or, without a crates.io release: cargo install --git https://github.com/nickderobertis/llmlint --locked)
llmlint doctor # confirms oneharness is reachable
```
The installer honors `LLMLINT_VERSION` / `LLMLINT_INSTALL_DIR` (or the `--version`
/ `--to` flags), works on Linux, macOS, and Windows under a POSIX shell
(Git Bash / MSYS / WSL), and refuses an archive whose checksum does not match.
Each tagged release publishes prebuilt, checksummed binaries for those
platforms; on native Windows PowerShell, use `cargo install llmlint --locked`.
You also need a coding harness installed and authenticated (e.g. Claude Code).
See `oneharness list` / `oneharness detect --all`.
## Quick start
```console
llmlint init # write a starter llmlint.yml (config-lint plugin on)
llmlint init --with-template # ...and embed the prompt template to customize
$EDITOR llmlint.yml # write your rules
llmlint # lint the configured files
llmlint src/api/**/*.rs # ...or lint specific files
llmlint --format json # machine-readable output
```
## Configuration
`llmlint.yml` (discovered by walking up from the working directory; override with
`-c/--config`, repeatable):
```yaml
version: 1 # this config's published version (used when it is consumed as a plugin)
# Files linted when none are passed on the CLI.
files:
include: ["src/**/*.rs"]
exclude: ["**/generated/**"]
# Pull in shared rule sets / plugins with one line each. An entry is a local
# path or a URL (`http(s)://`, `file://`); pin a URL to a version with `@`.
plugins:
- "https://raw.githubusercontent.com/nickderobertis/llmlint/main/assets/config_lint.yml@1" # bundled: lints this config's own rules
- "https://example.com/org-rules.yml@1.2.3" # pinned; fetched + cached once
- "./team-rules.yml"
# Agents group rules and add reviewer context + harness/model/batch config.
# YAML anchors let you share prompt text with zero framework support.
agents:
architecture:
harness: claude-code # any id from `oneharness list`; omit to use oneharness's own default
model: opus
batch_size: 15 # rules per judge run (default 20)
prompt_template: | # appended to the master template before render
You are a senior software architect reviewing service boundaries.
rules:
- name: handlers_delegate_to_services # unique, terse, descriptive
description: |
TRUE when every HTTP handler delegates business logic to a service layer.
FALSE when a handler performs business logic (DB queries, domain rules)
inline.
agent: architecture # optional; omit to use the default agent
judges: 3 # optional; independent judges, majority wins (default 1)
files: # optional; override the target files for this rule
include: ["src/api/**"]
```
### Writing good rules
- **Phrase each rule as a positive invariant.** `holds = true` means the code
complies; `holds = false` is a violation that llmlint reports and fails on.
- **Make the true/false outcome unambiguous and mutually exclusive** — state when
it is true *and* when it is false. The bundled config-lint plugin (the
`config_lint.yml` URL above) lints your config for exactly this, plus
descriptive (non-placeholder) names that match what each rule checks.
- **Names** are unique, terse, and descriptive (`^[A-Za-z][A-Za-z0-9_]*$`); they
become the JSON keys of the structured output.
### The prompt template
llmlint renders the judge's system prompt from a
[minijinja](https://docs.rs/minijinja) (Jinja2-style) template. The bundled
default lives in [`assets/default_template.md`](assets/default_template.md); embed
a copy to customize with `llmlint init --with-template`, or set `prompt_template`
yourself. The top-level `prompt_template` *replaces* the master template; an
agent's `prompt_template` is **appended** to it before rendering, so reviewer
context you add per-agent sees the same variables.
Exactly two variables are in scope when a template renders:
| Variable | Type | Description |
| --- | --- | --- |
| `files` | list of strings | The target file paths for this run — relative to the working directory, always forward-slashed (so a Windows run reads the same as Linux/macOS). |
| `rules` | list of objects | The rules in this batch. Each has `.name` (the identifier, also the JSON key in the structured output) and `.description` (the invariant to judge). |
```jinja
## Target files
{% for f in files %}- {{ f }}
{% endfor %}
## Rules to evaluate
{% for r in rules %}### {{ r.name }}
{{ r.description }}
{% endfor %}
```
A run is one `(agent, file set, judge)` batch, so `rules` is that batch's slice
(see `batch_size`), not necessarily every rule in the config.
### Judges and voting
`judges: N` runs a rule through `N` independent judges and takes the **majority**
verdict. `N` must be **odd** (1, 3, 5, …) so the vote can't tie — an even count is
a config error. Only rules that opt in pay the extra cost: judge 1 runs all rules,
judge 2 only the rules with `judges >= 2`, and so on.
### oneharness passthrough
llmlint lets oneharness discover its own `oneharness.toml` by default. To force a
specific oneharness config, use `--oneharness-config <path>` (or `oneharness.config`
in the llmlint config); it is forwarded via oneharness's `--config`. Override the
binary with `--oneharness-bin` or `$LLMLINT_ONEHARNESS_BIN`.
### Plugins (shared rule sets)
`plugins` pulls other llmlint configs into this one — their rules and agents are
merged in; the root config keeps the top-level settings (template, files,
oneharness). Each entry is a config file:
- a **local path** (`./team-rules.yml`), resolved relative to the including file;
- a **URL** — `http(s)://` (fetched over HTTPS) or `file://` (read directly).
Resolution is **transitive**: a pulled-in config's own `plugins` are pulled in
turn, and so on. Diamonds and cycles are de-duplicated (each config loads once),
and the chain is bounded at a depth of 100 to fail fast on a pathological graph.
URL fetching is built in (a pure-Rust HTTPS client — no `curl` or other external
tools, no system OpenSSL) and honors the standard `HTTP(S)_PROXY` / `NO_PROXY`
env vars. The bundled config-lint plugin ships inside the binary and resolves
**offline**.
A URL may be **pinned to a version** with an `@` suffix matching the plugin
config's own top-level `version`: `@1` accepts any `1.x`, `@1.2` any `1.2.x`,
`@1.2.3` exactly that. The pin is both an assertion (a mismatch is a hard error)
and the **cache key**: a pinned URL is fetched once into the cache and reused on
later runs without refetching — bump the pin to pull a new version. An *unpinned*
URL is fetched every run.
The cache lives under `$XDG_CACHE_HOME/llmlint/plugins` (override with
`LLMLINT_CACHE_DIR`). Set `LLMLINT_PLUGIN_REFRESH=1` to force a refetch.
## Commands & exit codes
- `llmlint [FILES...]` — lint (the default). `--format human|json`, `--agent`,
`--rule`, `--max-parallel`, `--timeout`, `--cwd`.
- `llmlint init` — write a starter config (`--with-template`, `--global`, `--force`).
- `llmlint config` — print the merged config and its sources as JSON.
- `llmlint doctor` — check that oneharness is installed and reachable.
Exit codes: `0` all rules hold · `1` at least one violation · `2` usage,
configuration, or harness error (could not complete the lint).
## Development
```console
just bootstrap # toolchain components + fetch (from a clean clone)
just check # full gate: fmt, clippy -D warnings, tests + 95% coverage, docs
just test-e2e # the e2e binary journeys in isolation
just deps-check # cargo deny + cargo machete
just lint-live # opt-in: ad-hoc lint against the REAL oneharness + a real harness
just live-claude # opt-in: live e2e — built llmlint → real oneharness → real harness
```
Tests drive the real `llmlint` binary against a hermetic mock-oneharness fixture.
The live tier (`just live-claude`, and the ad-hoc `just lint-live`) drives the
whole stack end to end against a real, authenticated harness — the only thing that
makes real model calls, and out of the `check` gate. It runs on PRs in its own
workflow across Linux/macOS/Windows, so a missing CLI, auth, or oneharness is a
hard failure, not a skip. See `AGENTS.md` and `tests/AGENTS.md`.
## License
MIT — see [LICENSE](LICENSE).