feat: initial rpm-changelog composite action

Generates an rpm %changelog entry from git history and prepends it
to the target spec file. Runs in release CI so every tag push gets
a fresh dated entry covering the commits since the previous matching
tag. Avoids stale dates, forgotten bumps, and bogus-weekday warnings.

Inputs: spec path, version, optional release suffix, author,
tag-pattern, exclude-patterns. The last two make the defaults (v*
tags, filter bump-version chores and merges) tweakable for projects
with different conventions.

Migrated from inline logic in helexa/cortex so any project can
adopt the same pattern with a single uses: reference.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

README.md

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+# rpm-changelog
+
+Gitea composite action that generates an rpm `%changelog` entry from
+git history and prepends it to a spec file. Designed to run during
+release CI so the changelog never drifts out of sync with the code.
+
+## Why use this
+
+Hand-maintained rpm `%changelog` sections drift. The day-of-week gets
+stale, the version lags behind tags, and the description stops
+matching what actually changed. This action:
+
+- Finds the previous release tag (default pattern `v*`).
+- Collects commits between that tag and `HEAD` via `git log`.
+- Filters out noise (bump-version bot commits, merge commits — both
+  configurable).
+- Writes a fresh `%changelog` entry with today's date, the release
+  author, and the new version.
+- Prepends it to the spec file's existing `%changelog` section.
+
+Because the date is generated at build time, `rpmbuild` will never
+warn about bogus weekdays and the entry always reflects what changed
+since the last release.
+
+## Requirements
+
+The consumer workflow must check out the repo with full git history:
+
+```yaml
+- uses: actions/checkout@v4
+  with:
+    fetch-depth: 0
+```
+
+Without this, `git describe` can't see prior tags and the entry will
+default to "No user-visible changes" on every release.
+
+## Inputs
+
+| Input              | Required | Default                                       | Description                                                                 |
+| ------------------ | -------- | --------------------------------------------- | --------------------------------------------------------------------------- |
+| `spec`             | yes      | —                                             | Path to the rpm spec file to update.                                        |
+| `version`          | yes      | —                                             | Version string for the new entry (without release suffix), e.g. `0.1.10`.   |
+| `release`          | no       | `1`                                           | Release suffix to append after the version.                                 |
+| `author`           | no       | `Gitea Actions <actions@git.lair.cafe>`       | Name and email for the entry.                                               |
+| `tag-pattern`      | no       | `v*`                                          | Glob pattern for release tags, used to locate the previous release.         |
+| `exclude-patterns` | no       | (see below)                                   | Newline-separated `grep -E` patterns to drop from the generated log.        |
+
+Default `exclude-patterns`:
+
+```
+^- chore: bump version
+^- Merge
+```
+
+## Usage
+
+```yaml
+jobs:
+  srpm:
+    runs-on: fedora
+    if: startsWith(github.ref, 'refs/tags/v')
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Determine version
+        id: version
+        run: echo "VERSION=${GITHUB_REF#refs/tags/v}" >> "$GITHUB_OUTPUT"
+
+      - name: Stamp version in spec
+        run: sed -i "s/^Version:.*/Version:        ${{ steps.version.outputs.VERSION }}/" mypackage.spec
+
+      - name: Update changelog
+        uses: https://git.lair.cafe/actions/rpm-changelog@v1
+        with:
+          spec: mypackage.spec
+          version: ${{ steps.version.outputs.VERSION }}
+
+      - name: Build SRPM
+        run: rpmbuild -bs mypackage.spec --define "_sourcedir $(pwd)"
+```
+
+Note the fully-qualified URL in `uses:` — the Gitea instance's
+`DEFAULT_ACTIONS_URL` points at github.com, so internal actions must
+be referenced by absolute URL.
+
+## Versioning
+
+Pin to a major version tag (`@v1`) for automatic patch/minor updates.
+Pin to an exact tag (`@v1.0.2`) to freeze.
+
+## Behaviour notes
+
+- If no previous tag matching `tag-pattern` exists (first release),
+  the entry body becomes `- No user-visible changes`.
+- If the filter removes every commit (e.g. release contained only
+  bump-version chores), body is `- No user-visible changes`.
+- The spec file must already contain a `%changelog` line — the
+  action will error out rather than mangle an unmarked file.
+- The date uses UTC (`date -u`) so runners in different timezones
+  produce deterministic output.

action.yml

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+name: 'Generate RPM %changelog entry'
+description: >
+  Collect commits since the previous release tag and prepend a
+  properly-formatted %changelog entry to an rpm spec file. Keeps
+  the changelog in sync with git history automatically on every
+  release, avoiding stale dates and forgotten bumps.
+author: 'helexa'
+
+branding:
+  icon: file-text
+  color: blue
+
+inputs:
+  spec:
+    description: 'Path to the rpm spec file to update.'
+    required: true
+  version:
+    description: >
+      Version string for the new entry (without release suffix).
+      Typically derived from the git tag, e.g. "0.1.10".
+    required: true
+  release:
+    description: 'Release suffix to append after the version.'
+    required: false
+    default: '1'
+  author:
+    description: >
+      Name and email for the changelog entry, formatted as
+      "Name <email@example.com>".
+    required: false
+    default: 'Gitea Actions <actions@git.lair.cafe>'
+  tag-pattern:
+    description: >
+      Glob pattern for release tags, used to locate the previous
+      release. Default matches the conventional "v*" scheme.
+    required: false
+    default: 'v*'
+  exclude-patterns:
+    description: >
+      Newline-separated list of grep -E patterns (anchored on the
+      bullet "- " prefix) to drop from the generated log. Defaults
+      filter out bump-version bot commits and merge commits.
+    required: false
+    default: |
+      ^- chore: bump version
+      ^- Merge
+
+runs:
+  using: composite
+  steps:
+    - name: Generate changelog entry
+      shell: bash
+      env:
+        SPEC: ${{ inputs.spec }}
+        VERSION: ${{ inputs.version }}
+        RELEASE: ${{ inputs.release }}
+        CHANGELOG_AUTHOR: ${{ inputs.author }}
+        TAG_PATTERN: ${{ inputs.tag-pattern }}
+        EXCLUDE_PATTERNS: ${{ inputs.exclude-patterns }}
+      run: |
+        bash "${{ github.action_path }}/scripts/generate-rpm-changelog.sh" \
+          "$SPEC" "$VERSION"

scripts/generate-rpm-changelog.sh

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+#!/bin/bash
+# Generate an rpm %changelog entry for this release and prepend it to
+# the spec's existing %changelog section.
+#
+# Usage: generate-rpm-changelog.sh <spec-file> <version>
+#
+# Environment overrides:
+#   CHANGELOG_AUTHOR  — "Name <email>", default "Gitea Actions <actions@git.lair.cafe>"
+#   RELEASE           — release suffix, default "1"
+#   TAG_PATTERN       — glob for release tags, default "v*"
+#   EXCLUDE_PATTERNS  — newline-separated grep -E patterns to drop
+#
+# Collects commits since the previous matching tag, drops filtered
+# lines (bump-version chore commits, merges, etc.), and writes a
+# dated entry.
+
+set -euo pipefail
+
+SPEC="$1"
+VERSION="$2"
+AUTHOR="${CHANGELOG_AUTHOR:-Gitea Actions <actions@git.lair.cafe>}"
+RELEASE="${RELEASE:-1}"
+TAG_PATTERN="${TAG_PATTERN:-v*}"
+EXCLUDE_PATTERNS="${EXCLUDE_PATTERNS:-$'^- chore: bump version\n^- Merge'}"
+
+if [ ! -f "$SPEC" ]; then
+  echo "error: spec file not found: $SPEC" >&2
+  exit 1
+fi
+
+if ! grep -q '^%changelog' "$SPEC"; then
+  echo "error: no %changelog section in $SPEC — refusing to mangle" >&2
+  exit 1
+fi
+
+# Find the previous release tag (exclude the current tag at HEAD).
+PREV_TAG=$(git describe --tags --abbrev=0 --match="$TAG_PATTERN" HEAD^ 2>/dev/null || echo "")
+
+if [ -n "$PREV_TAG" ]; then
+  RAW=$(git log --no-merges --pretty=format:'- %s' "${PREV_TAG}..HEAD")
+
+  # Build a combined grep -E pattern from the exclude list; drop blanks.
+  COMBINED=""
+  while IFS= read -r pat; do
+    [ -z "$pat" ] && continue
+    if [ -z "$COMBINED" ]; then
+      COMBINED="$pat"
+    else
+      COMBINED="${COMBINED}|${pat}"
+    fi
+  done <<< "$EXCLUDE_PATTERNS"
+
+  if [ -n "$COMBINED" ]; then
+    LOG=$(printf '%s\n' "$RAW" | grep -Ev "$COMBINED" || true)
+  else
+    LOG="$RAW"
+  fi
+else
+  LOG=""
+fi
+
+if [ -z "$LOG" ]; then
+  LOG="- No user-visible changes"
+fi
+
+DATE=$(LC_ALL=C date -u +'%a %b %d %Y')
+ENTRY="* ${DATE} ${AUTHOR} - ${VERSION}-${RELEASE}
+${LOG}
+"
+
+# Prepend the entry to the %changelog section.
+TMP=$(mktemp)
+awk -v entry="$ENTRY" '
+  inserted == 0 && /^%changelog[[:space:]]*$/ {
+    print
+    print entry
+    inserted = 1
+    next
+  }
+  { print }
+' "$SPEC" > "$TMP"
+
+mv "$TMP" "$SPEC"
+
+echo "Added changelog entry for ${VERSION}-${RELEASE}:"
+echo "$ENTRY"