[jdx]

https://entire.io/gh/jdx/mise/trails/459

Adds an internal helper that sets keys on a YAML document by editing its syntax tree in place, so comments, key order, quoting, and flow/block style on everything else survive. Nothing calls it yet; it is the foundation for the merge dotfile entries stacked on top (#13986).

merge_yaml("# note\ntheme: dark  # ui\nkeep: 1\n", "theme: light\n")
// => "# note\ntheme: light  # ui\nkeep: 1\n"

• Mappings that exist on both sides merge recursively; any other value, including a sequence, is replaced by the source's. A value that already equals the source's is left untouched, formatting included.
• An empty or comment-only target is an empty mapping. A non-mapping root or a multi-document file is an error.

It is built on yaml-edit (pure Rust on rowan, MSRV 1.70). aube's comment-preserving path uses yamlpatch/yamlpath, which are pinned below their latest releases for MSRV and pull in tree-sitter; this avoids both. yaml-edit adds rowan 0.16 and nothing else new to Cargo.lock.

Verified with unit tests, cargo clippy --workspace --all-features --all-targets -- -D warnings, and cargo +1.95 check.

AI-assisted — Tool: Claude Code; model: anthropic/claude-sonnet-5-5; version: 2.1.288.

🤖 Generated with Claude Code

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Note

Low Risk
New internal utility with no production call sites yet; dependency adds yaml-edit/rowan but behavior is covered by unit tests.

Overview
Adds a merge_yaml helper in mise-util that merges a source YAML mapping into an existing target by editing the text in place via the new yaml-edit dependency, so comments, key order, quoting, and flow/block style on untouched keys stay intact.

Merge rules: nested mappings recurse; sequences and other values are replaced from the source; equal values are left unchanged. Empty or comment-only targets become empty mappings; non-mapping roots and multi-document files error. A post-merge verify step re-parses with serde_yaml to ensure every source key is present, and replace_value works around a yaml-edit block-scalar line-break bug. The module is exported but not wired to any callers yet (intended for upcoming dotfile merge support).

^{Reviewed by Cursor Bugbot for commit 688eb51. Bugbot is set up for automated code reviews on this repo. Configure here.}

Summary by CodeRabbit

• New Features

  • Added YAML configuration merging that combines nested mappings, adds missing keys, and replaces values where needed.
  • Existing formatting and untouched content are preserved where possible, and unchanged values are left as-is.
  • Empty or comment-only targets can be used as the starting point for a merge.

• Bug Fixes

  • Invalid YAML, multiple-document input, and non-mapping root values now return errors instead of being merged.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: Repository YAML (base), Central YAML (inherited), Organization UI (inherited)
• Review profile: CHILL
• Plan: Advanced
• Run ID: 9b3dda4f-d5f8-4f62-8faa-cae73fc588ec

📥 Commits

Reviewing files that changed from the base of the PR and between 83f3e90 and 688eb51.

⛔ Files ignored due to path filters (1)

• Cargo.lock is excluded by !**/*.lock

📒 Files selected for processing (3)

• crates/mise-util/Cargo.toml
• crates/mise-util/src/lib.rs
• crates/mise-util/src/yaml_merge.rs

Included review availability: This review used your included allowance. Your plan provides up to 10 included reviews per hour; 4 remain after this review.

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📝 Walkthrough

Walkthrough

Adds and exports merge_yaml, which merges source YAML mappings into a target while preserving untouched text and formatting. The function checks document roots, verifies the merged values, and returns errors for malformed YAML, multiple documents, and invalid roots.

Changes

YAML merge utility

Layer / File(s)	Summary
Public entry point and YAML input handling crates/mise-util/Cargo.toml, crates/mise-util/src/lib.rs, crates/mise-util/src/yaml_merge.rs	Adds the yaml-edit dependency and exports yaml_merge. Parses YAML input and checks document roots.
Merge, preserve formatting, and verify output crates/mise-util/src/yaml_merge.rs	Recursively merges mappings, replaces differing values, and handles block-scalar replacement. Tests cover formatting preservation, merge behavior, idempotence, and errors.

Priority: ⬇️ Low

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

Change: Feature

Merge Risk: ⚪ Minimal · up to 688eb

No established issue currently blocks merging this helper.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: adding a comment-preserving YAML merge helper.
Docstring Coverage	✅ Passed	Docstring coverage is 94.12% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 17 functions across 2 files. (1 skipped: 1 …
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.

• Autopilot · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts

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[socket-security]

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	cargo/​yaml-edit@​0.3.2

View full report

[greptile-apps]

Confidence Score: 5/5

[Medium risk] Adds a YAML merge utility with a new dependency.

The PR appears safe to merge; no new actionable issue was found.

Summary

Adds merge_yaml to merge YAML mappings while keeping untouched text.

• Nested mappings merge recursively; other values are replaced.
• The latest changes replace block scalars without joining the following key onto their line.
• The helper now checks that the result parses and contains the source values.
• Added tests address the previous formatting-test suggestion with flow mappings, block scalars, and nested indentation.

_{Reviews (2) · Last reviewed commit: "fix(util): replace YAML block scalars cl..."}

[github-actions]

Instruction counts

Nothing was compared, and so nothing was gated. No series appears on both sides: either the base has no measurements recorded, or the two were measured on different runner classes, which are deliberately not comparable — counts shift between machine types by more than a real regression does.

New, nothing to compare against: env on jdx-perf-v1-ubuntu24.04-x64-mise-rust1.97.1-img5263c143, hook-env on jdx-perf-v1-ubuntu24.04-x64-mise-rust1.97.1-img5263c143, ls on jdx-perf-v1-ubuntu24.04-x64-mise-rust1.97.1-img5263c143, registry on jdx-perf-v1-ubuntu24.04-x64-mise-rust1.97.1-img5263c143, startup on jdx-perf-v1-ubuntu24.04-x64-mise-rust1.97.1-img5263c143

_{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.}

_{688eb512357b vs 2f0975c0e883 · measured on the runner, not pushed to the history.}