> ## Documentation Index
> Fetch the complete documentation index at: https://mehen.ophi.dev/llms.txt
> Use this file to discover all available pages before exploring further.
# GitHub Action
> Drop the ophi-dev/mehen action into a workflow to publish per-PR metric trends.
The official **`ophi-dev/mehen`** GitHub Action computes changed-file metric trends on every pull
request, compares them against the base branch, and publishes a sticky comment with the deltas. It is
the primary consumption surface for mehen today.
Each cell shows the new value with the base-branch value in parentheses and a colored indicator —
🟢 improvement, 🔴 regression, ⚪ no material change — so reviewers see at a glance which files a PR
made more or less complex.
## Minimal workflow
```yaml .github/workflows/mehen.yml theme={null}
name: mehen
on: pull_request
jobs:
mehen:
runs-on: ubuntu-latest
permissions:
contents: read
pull-requests: write
issues: write
steps:
- uses: actions/checkout@v6
with:
fetch-depth: 0
- uses: ophi-dev/mehen@v1
with:
paths: src
```
That's the whole setup. The action installs the `mehen` CLI, runs `mehen diff` against the PR's base
branch, and posts a sticky comment with the per-file metric deltas.
## Polyglot monorepo
For monorepos, pass each tracked root and let mehen pick supported languages from changed files in those
trees:
```yaml theme={null}
- uses: ophi-dev/mehen@v1
with:
paths: |
crates/api/src
apps/web/src
tools
thresholds: |
cyclomatic=5
cognitive=4
loc.lloc=120
```
## Inputs
| Input | Default | Description |
| ------------------- | --------------------------- | --------------------------------------------------------------------------------------------------------------------- |
| `version` | `""` (latest) | Version of the mehen npm package to run. |
| `install-method` | `npm` | How to provide the mehen CLI: `npm`, `cargo`, or `path`. |
| `mehen-path` | `mehen` | Path to a mehen executable when `install-method: path`. |
| `node-version` | `24` | Node.js version used by the action runner. |
| `paths` | `.` | Repository-relative files or directories to compare. Newline, comma, or semicolon separated. |
| `include` | `""` | Glob patterns to include. |
| `exclude` | `""` | Glob patterns to exclude. |
| `exclude-tests` | `true` | Exclude common test-file patterns (`*_test.go`, `**/__tests__/**`, `*.spec.ts`) on top of any user-provided excludes. |
| `metrics` | `""` | Comma-separated metrics passed to `mehen diff`. |
| `from` | `""` | Base git revision. Defaults to the PR base branch or `main`. |
| `to` | `""` | Head git revision. Defaults to the PR head SHA or `HEAD`. |
| `show-unchanged` | `false` | Include files where all selected metrics are unchanged. |
| `comment` | `true` | Create or update a pull request comment. |
| `github-token` | (workflow token) | GitHub token used to update PR comments. |
| `thresholds` | `""` | Adverse per-file delta limits, e.g. `cyclomatic=5,cognitive=3,loc.lloc=100`. |
| `fail-on-threshold` | `true` | Fail the action when any configured threshold is exceeded. |
| `comment-title` | `## 📊 Source Code Metrics` | Markdown heading used for the sticky comment. |
## Outputs
| Output | Description |
| ----------------- | ----------------------------------------------- |
| `violations` | Number of threshold violations. |
| `report_json` | Path to the JSON diff report produced by mehen. |
| `report_markdown` | Path to the rendered Markdown report. |
## Permissions
The action needs to write PR comments:
```yaml theme={null}
permissions:
contents: read
pull-requests: write
issues: write
```
`contents: read` lets the runner check out the repo. `pull-requests: write` and `issues: write` let the
action upsert the sticky comment.
## Sticky comment
The action posts a single comment on the PR and updates it on each push instead of stacking new
comments. The Markdown layout, cell format, and callout catalog are documented on the
[PR comment design](/guides/pr-comment-design) page.
## Markdown documentation section
When a PR touches Markdown files, `mehen diff` emits a **Documentation Metrics** section inside the
same sticky comment, anchored by `` (visible in the screenshot above). It carries a
five-column headline table (DMI, Words, FKGL/Tateishi RS, Link Debt, Filler Risk), severity-ranked
callouts drawn from a fixed template catalog, and a collapsed drill-down with the deeper structural,
wording, and readability tables. On code-only PRs the section is suppressed entirely. The full
specification — anchor rules, cell format, callout catalog, and `--fail-on` gating — is on the
[PR comment design](/guides/pr-comment-design) page.
## SQL in the diff
SQL files are analyzed automatically and appear in the same **Source Code Metrics** table on the PR
comment. Because SQL and source-code files publish different metric families, a mixed PR renders a
single table whose columns are the union of each language's defaults — every row fills only the
columns its analyzer emits, and the rest render as `–`. This keeps SQL changes visible on the default
action path instead of silently dropping out. See [`mehen diff`](/commands/diff) for how the default
metric set is resolved per file language.
## Examples
```yaml theme={null}
- uses: ophi-dev/mehen@v1
with:
paths: src
thresholds: |
cyclomatic=3
cognitive=3
fail-on-threshold: true
```
```yaml theme={null}
- uses: ophi-dev/mehen@v1
with:
paths: src
fail-on-threshold: false
```
```yaml theme={null}
- uses: ophi-dev/mehen@v1
with:
paths: src
version: "1.1.0"
```
```yaml theme={null}
- run: cargo binstall --git https://github.com/ophi-dev/mehen mehen
- uses: ophi-dev/mehen@v1
with:
install-method: path
mehen-path: $(which mehen)
paths: src
```
## See also
* [Commands → diff](/commands/diff) — the underlying CLI command.
* [Concepts → Thresholds and diffs](/concepts/thresholds-and-diffs).
* [PR comment design](/guides/pr-comment-design) — full Markdown spec.