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Danny Kopping
9f211ce5ae
## Problem The `lint/emdash` check fails on Graphite-stacked PRs. See [this failed run](https://github.com/coder/coder/actions/runs/28225390084/job/83616080375?pr=26650): ``` Base ref origin/graphite-base/26650 not found locally, fetching graphite-base/26650... ERROR: could not fetch base ref origin/graphite-base/26650. ERROR: could not determine base ref. make: *** [Makefile:768: lint/emdash] Error 1 ``` `scripts/check_emdash.sh` resolved its diff base by fetching `origin/$GITHUB_BASE_REF` and computing a merge-base. Graphite sets `GITHUB_BASE_REF` to a `graphite-base/<n>` ref that is ephemeral (it is not reliably present on origin), so the fetch fails and the check errors out instead of running. ## Fix `actions/checkout` checks out the PR **merge commit** (`refs/pull/<n>/merge`), whose **first parent (`HEAD^1`) is the exact base commit GitHub merged against**. Diffing `HEAD^1` against the checkout yields every change the PR makes against its base branch, for normal and Graphite-stacked PRs alike. No base-branch fetch, no merge-base computation, no `gh`-based deepen dance. - `scripts/check_emdash.sh`: use `HEAD^1` (the PR base commit) as the diff base in CI. Drops `resolve_merge_base` and `fetch_base_ref`. Emits a clear error if `HEAD^1` is missing (checkout too shallow). - `.github/workflows/ci.yaml`: bump the `lint` job checkout to `fetch-depth: 2` so `HEAD^1` is present with no runtime fetch. Local dev behavior (merge-base against `origin/main`) is unchanged. ## Verification - `make lint/emdash`, `make lint/shellcheck`, `make lint/actions/actionlint` pass. - Simulated the CI path with `GITHUB_BASE_REF` set: the check resolves to `HEAD^1` without fetching and still flags an added line containing an emdash. <details> <summary>Why the merge commit's first parent</summary> For a `pull_request` checkout of `refs/pull/<n>/merge`: - `HEAD` = GitHub's synthetic PR merge commit - `HEAD^1` = the exact base commit used for the merge - `HEAD^2` = the PR head commit `git diff HEAD^1 HEAD` is the full-tree diff from the base snapshot to the merged result, i.e. all of the PR's changes against its base. This is immutable and always local (given depth >= 2), unlike base branch refs which are mutable and, for Graphite stacks, ephemeral. </details> --- This PR was generated by Coder Agents on behalf of @dannykopping.