GitHub Action: redline the .docx files a PR changes

[JSv4]

Closes #12.

This makes the repository usable directly as a GitHub Action, per the design discussed on the issue (inspired by vanbroup/build-guidelines-action): explicit file-pair configuration, an author input for the tracked changes, plus an auto-detect mode that redlines every .docx a pull request changes.

Minimal usage

on: pull_request
jobs:
  redline:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
      - uses: JSv4/Python-Redlines@main

For each .docx the PR modifies (or renames), the action extracts the base and head versions from git, runs the redline engine, writes redlines/<path>/<name>.redline.docx with native Word tracked changes, uploads the lot as a workflow artifact, and posts a job-summary table (file → revision count → outputs). Explicit-pair mode (original: + modified: inputs) covers the "just compare these two files" case from the issue thread.

What's in the change

• action.yml — composite action. Installs python-redlines[docxodus|ooxmlpowertools] from PyPI (prebuilt engine wheels — nothing compiles at run time), runs the driver, uploads the artifact, links it from the summary. Inputs: files globs, base-ref/head-ref, author, engine, comparison (wmlcomparer/docxdiff), detect-moves, output-dir, html-preview, summary, upload-artifact/artifact-name, and version pins for the pip package and preview tool. Outputs: count, any-changes, redlines (JSON records), artifact-url.
• action/redline_changed.py — stdlib-only driver. Resolves the comparison window from the triggering event: PR base/head with merge-base semantics (matches the PR "files changed" view; falls back with a warning on shallow clones), push before/after (with a parent-commit fallback for new branches), or HEAD~1..HEAD; missing commits are fetched by SHA. Diffs with rename detection and case-insensitive glob pathspecs, reads both sides out of git (independent of checkout state — important on PR merge commits), and reports added/deleted files without redlining them (no counterpart to compare). Pure renames skip the engine. A per-file engine failure is reported and fails the run only after every file is processed.
• HTML previews — html-preview: auto|true|false renders each redline to browser-viewable HTML (ins/del/move markup) via the Docxodus Docx2Html dotnet tool's new --track-changes mode, added in the companion PR docx2html: add --track-changes and story rendering flags Docxodus#269. Until that ships in a Docxodus release (≥ 7.1.0 on NuGet), the default auto mode detects the missing capability and skips with a warning instead of producing a misleading "all changes accepted" preview; true makes it a hard requirement; false skips the .NET setup entirely.
• Tests — tests/test_action_script.py (28 tests): input validation, --name-status -z parsing, ref resolution across event shapes, pathspec filtering, output-path safety for absolute sources (caught a real bug where an absolute modified: path escaped output-dir), and two integration tests running the real engine over the repo fixtures (9 revisions, matching the documented fixture count).
• Self-test workflow — .github/workflows/redline-action-test.yml runs the action from the checkout in both modes and asserts on outputs; the auto-detect job builds a synthetic two-commit docx history in the runner's clone.
• Docs — README "GitHub Action" section with the full input table; CLAUDE.md maintenance notes.

Verification

• python -m pytest tests/ — 68 passed (40 existing + 28 new).
• Driver exercised end-to-end locally in both modes against the published python-redlines==0.3.0 wheels: auto-detect over a scratch repo (modified + added + deleted docx classified correctly, 9 revisions) and explicit-pair with a locally-built docx2html --track-changes producing an HTML preview with 11 ins/del elements.
• The self-test workflow runs on this PR itself.

🤖 Generated with Claude Code

https://claude.ai/code/session_0142X9VTMpdo639kHKQa4PE1

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