feat(rust): port ci git-refs to native Rust

[jd]

The Rust binary now serves mergify ci git-refs natively. The
Python implementation (mergify_cli/ci/cli.py:git_refs) and
its tests are removed in the same PR — port-and-delete keeps a
single live copy.

The previous commit landed a live-smoke test pinning the
Base: HEAD^ / Head: HEAD fallback contract. That same
test now exercises the Rust path.

The command detects the base/head git references for the
current build:

1. Buildkite env (BUILDKITE_PULL_REQUEST and friends)
2. GitHub Actions event payload at $GITHUB_EVENT_PATH
3. refs/notes/mergify/<branch> git notes (for merge-queue
   draft PRs created by the Mergify backend)
4. The MQ PR body's YAML metadata block (fallback for tools
   that can't read git notes)
5. Literal HEAD^..HEAD when none of the above match

Three output formats:

• text (default): Base: <ref> and Head: <ref> on
  two lines.
• shell: MERGIFY_GIT_REFS_{BASE,HEAD,SOURCE}=... lines
  for eval; values are properly shell-quoted.
• json: a single JSON object {"base":..., "head":..., "source":...}.

The command also writes base=...\nhead=... to
$GITHUB_OUTPUT when set, and calls buildkite-agent meta-data set when BUILDKITE=true.

This commit introduces two shared helper modules in the
mergify-ci crate that the next port (ci queue-info)
will reuse:

• github_event: GitHub Actions event payload deserialization
  (GITHUB_EVENT_PATH).
• queue_metadata: MQ YAML fenced-block extraction from PR
  bodies and git notes.

The notes reader is injected as a trait-object callback so unit
tests can exercise the note-driven detection path without
touching a real git repository; the production path shells out
via real_notes_reader.

Adds the serde_yaml_ng dep (YAML parser) to the
mergify-ci crate.

12 new git-refs + 2 format round-trip tests plus 8
event/metadata tests in the shared helpers. The Python
git-refs tests in mergify_cli/tests/ci/test_cli.py are
removed.

Co-Authored-By: Claude Opus 4.7 (1M context) noreply@anthropic.com

Depends-On: #1404

[jd]

This pull request is part of a Mergify stack:

#	Pull Request	Link
1	test(ci): add live smoke test for ci git-refs	#1404
2	feat(rust): port ci git-refs to native Rust	#1405	👈
3	test(ci): add live smoke test for ci queue-info	#1406
4	feat(rust): port ci queue-info to native Rust	#1407
5	test(queue): add live smoke test for queue status	#1409
6	feat(rust): port queue status to native Rust	#1359
7	test: derive native queue commands from the binary, not a hardcoded list	#1366
8	test(queue): add live smoke test for queue show	#1408
9	feat(rust): port queue show to native Rust	#1399
10	test(skill): port the skill-references test to Rust	#1414

[mergify]

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• depends-on = Mergifyio/mergify-cli#1404 [⛓️ test(ci): add live smoke test for ci git-refs #1404]

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  • author = mergify-ci-bot
  • author = renovate[bot]

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• title ~= ^(fix|feat|docs|style|refactor|perf|test|build|ci|chore|revert|ui)(?:\(.+\))?:

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[jd]

Revision history

#	Type	Changes	Reason	Date
1	initial	2d49d23		2026-05-11 14:08 UTC
2	rebase	2d49d23 → 0d7c20c		2026-05-11 14:08 UTC
3	rebase	0d7c20c → d0a28d3		2026-05-11 14:59 UTC
4	rebase	d0a28d3 → c12b430		2026-05-11 20:59 UTC
5	rebase	c12b430 → a9ed3f2 (rebase only)		2026-05-12 07:44 UTC

[Copilot]

Pull request overview

Ports mergify ci git-refs from the Python click CLI to a native Rust implementation in the mergify-ci crate, and wires the Rust binary dispatcher to run it natively (while removing the Python CLI entrypoint/tests for this command).

Changes:

• Add native Rust ci git-refs command with base/head detection, multiple output formats, and CI side-effects (GITHUB_OUTPUT / Buildkite meta-data).
• Introduce shared Rust helpers for GitHub Actions event payload parsing and merge-queue YAML metadata extraction.
• Remove the Python click git_refs command and its CLI-level tests; register ci git-refs as a native subcommand in the Rust mergify binary.

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
mergify_cli/tests/ci/test_cli.py	Removes Python CLI tests for ci git-refs now that execution is native Rust.
mergify_cli/ci/cli.py	Deletes the Python click ci git-refs command implementation (now handled by Rust).
crates/mergify-cli/src/main.rs	Adds native dispatch + clap plumbing for mergify ci git-refs --format ....
crates/mergify-ci/src/lib.rs	Exposes new git_refs, github_event, and queue_metadata modules.
crates/mergify-ci/src/github_event.rs	Adds GitHub Actions event payload deserialization + loader.
crates/mergify-ci/src/queue_metadata.rs	Adds MQ PR-body fenced YAML extraction + detection helper.
crates/mergify-ci/src/git_refs.rs	Implements detection logic, output formats, and CI side-effects for ci git-refs.
crates/mergify-ci/Cargo.toml	Adds serde_yaml_ng dependency for YAML parsing.
Cargo.lock	Locks new dependencies (including serde_yaml_ng) and transitive updates.

---

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[mergify]

Merge Queue Status

• ✅ Entered queue — 2026-05-12 14:03 UTC · Rule: default
• ✅ Checks passed · on draft merge queue: embarking main (8fcef7c) and #1405 together #1415
• ✅ Merged — 2026-05-12 14:20 UTC · at a9ed3f27f55fba55bdb450cf67d790c44304de0d · squash

This pull request spent 16 minutes 44 seconds in the queue, including 16 minutes 16 seconds running CI.

Required conditions to merge

• depends-on = Mergifyio/mergify-cli#1404 [⛓️ test(ci): add live smoke test for ci git-refs #1404]
  • feat(rust): port ci git-refs to native Rust #1405
• all of [🛡 Merge Protections rule Enforce conventional commit]:
  • title ~= ^(fix|feat|docs|style|refactor|perf|test|build|ci|chore|revert|ui)(?:\(.+\))?:
    • feat(rust): port ci git-refs to native Rust #1405
• all of [🛡 Merge Protections rule 👀 Review Requirements]:
  • any of:
    • #approved-reviews-by>=2
      • feat(rust): port ci git-refs to native Rust #1405
    • author = dependabot[bot]
      • feat(rust): port ci git-refs to native Rust #1405
    • author = mergify-ci-bot
      • feat(rust): port ci git-refs to native Rust #1405
    • author = renovate[bot]
      • feat(rust): port ci git-refs to native Rust #1405
• all of [🛡 Merge Protections rule 📕 PR description]:
  • body ~= (?ms:.{48,})
    • feat(rust): port ci git-refs to native Rust #1405
• all of [🛡 Merge Protections rule 🔎 Reviews]:
  • #changes-requested-reviews-by = 0
    • feat(rust): port ci git-refs to native Rust #1405
  • #review-requested = 0
    • feat(rust): port ci git-refs to native Rust #1405
  • #review-threads-unresolved = 0
    • feat(rust): port ci git-refs to native Rust #1405
• all of [🛡 Merge Protections rule 🤖 Continuous Integration]:
  • all of:
    • check-success=ci-gate