ci: restore rust-cache

[jdx]

Restores Swatinem/rust-cache for GitHub Actions while keeping mbx installed and the Cargo wrapper enabled for local development.

GitHub workflows set MBX_DISABLE=1, so Actions bypass mbx and rely on rust-cache. Cache writes are restricted to trusted pushes on supported main, release, or tag refs; pull requests, including forks, restore only. hk remains the dedicated GitHub Actions test bed for mbx.

Validation:

• actionlint with workflow syntax checks
• git diff --check
• verified no local-development mbx configuration or guidance remains removed

Summary by CodeRabbit

• Chores
  • Replaced MBX-based workflow caching with standard Rust caching across test jobs.
  • Disabled MBX in performance, testing, and release automation.
  • Performance builds now use standard Cargo release builds.
  • Removed the custom MBX setup action and related cache configuration.
  • Reduced permissions requested by the trusted test workflow.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Central YAML (base), Organization UI (inherited)

Review profile: CHILL

Plan: Team

Run ID: 4784decb-901f-4487-bf09-a987d2a1d589

📥 Commits

Reviewing files that changed from the base of the PR and between 48cdaa8 and 3896da0.

⛔ Files ignored due to path filters (1)

• mise.lock is excluded by !**/*.lock

📒 Files selected for processing (4)

• .github/workflows/perf-pr.yml
• .github/workflows/perf.yml
• .github/workflows/release-plz.yml
• .github/workflows/test-impl.yml

Included review availability: Your plan provides up to 4 included reviews per hour; 2 remain after this review.

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📝 Walkthrough

Walkthrough

The workflows remove the mbx action and cache integration. Performance jobs use direct Cargo builds. Test jobs use Swatinem/rust-cache. Workflow permissions and environment settings are updated accordingly.

Changes

mbx integration removal

Layer / File(s)	Summary
Disable mbx in workflows .github/actions/mbx/action.yml, .github/workflows/release-plz.yml, .github/workflows/test-impl.yml, .github/workflows/test.yml	The mbx composite action is deleted. Workflow-level mbx disablement is added. The trusted job no longer requests OIDC token permissions.
Update performance workflows .github/workflows/perf.yml, .github/workflows/perf-pr.yml	Performance jobs remove mbx environment variables, mounts, initialization, metadata, and commands. The base-commit build uses cargo build --release.
Replace test caching .github/workflows/test-impl.yml	Linux, Windows, and MSRV jobs use Swatinem/rust-cache with job-specific keys. MSRV checks invoke Cargo directly. Cache saves remain limited to trusted main runs.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: ⚪ Minimal · up to 3896d

This change removes mbx from CI caching and performance builds while retaining trusted Rust cache writes for main-branch workflows. The supplied validation and workflow updates indicate no current merge-blocking production or user-impact risk.

Poem

A rabbit hops where mbx once ran
Rust cache cards now guide the plan
Cargo builds beneath the light
Windows, Linux, MSRV in flight
Old mounts fade from workflow streams
Green checks nibble build-time dreams

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the primary CI change: restoring Swatinem/rust-cache. It is concise and directly related to the pull request objectives.

Full details: Docstring Coverage

Explanation

No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0 files. (4 skipped: 4 unsupported.)

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[github-actions]

Instruction counts

benchmark	trend	instructions	Δ	wall (min)	Δ
markdown	▁█	380,405,802 → 380,433,312	+0.01%	63.08 → 62.88ms	-0.32%
startup	▁█	944,259 → 950,968	+0.71%	1.16 → 1.18ms	+1.94%

No instruction-count regression above 1%.

_{Only instruction counts gate. Wall clock is shown for context — on identical hardware it moves 4-20% run to run.}

_{Measured by tak — instruction-counted CLI benchmarks, stored in this repository's git notes.}

Shadow comparison

Parsing mise use -g node@20 against a shadow of mise's committed spec.
Reported, not gated: the shadow grows as the derive learns to express more, so
what to watch is the ratio rather than either column.

framework	stripped binary, bytes
usage	1344728
bpaf	2493216
clap	3101656

framework	instructions, cold parse	vs usage
usage	8530	—
clap	6316282	740x
bpaf	21909185	2568x

                                              min       p01       p10    median
usage-rs: argv -> struct                     1229      1252      1260      1266  ns
clap: build tree + parse -> struct        1804446   1812253   1820143   1829888  ns
bpaf: build parser + parse -> struct      5718858   5718858   5742958   5802366  ns

usage: argv -> struct                            1194 ns      1.19 µs
clap: build tree + parse -> struct            1835110 ns   1835.11 µs
clap: parse -> struct, tree reused              72321 ns     72.32 µs
clap: build tree only                         1064111 ns   1064.11 µs

_{3896da0c5929 vs f9b4ace5e1bd · measured on the runner, not pushed to the history.}