[rqbazan]

Summary

When the project already has a biome.json, rr plugins add biome patches it with edit-json. The kernel's engine re-stringifies the whole file: 2-space indent and one array item per line. Biome's formatter rejects that, so rr jsc / rr check failed right after the add. dx#276 fixed the create path; this fixes the patch path.

 install(ctx)  // @rrlab/biome-plugin, patch path
   edit-json biome.json   set /$schema (if-missing), include /extends @rrlab/biome-config
+  edit-text biome.json   format with the installed Biome (cwd = project, so the patched config applies)
+                         on any error → leave the text as it is (the add never fails)

 applyJsonEdits(source, edits)  // @rrlab/cli
+  if the edits changed nothing → return source verbatim (no reflow, reported "unchanged")
   return cjson.stringify(root, null, 2)

• The format step runs Biome synchronously (execFileSync), because edit-text is (source) => string. Widening it to accept a Promise would be a contract change, and an older kernel would write the Promise to disk. No other plugin spawns in install() today; ADR 017 records the choice.
• decisions/017-plugin-owned-format-of-patched-config.md (arch-critic): the plugin that owns a config file's tool formats what it patches. ADR 004 gets a pointer to it. The wider question, whether the kernel should format everything rr plugins add writes, is still open, and this doesn't close it.

Evidence

Non-TTY e2e with the worktree's packed @rrlab/cli + @rrlab/biome-plugin. Each project starts as a green Biome project (biome check exits 0), then runs rr plugins add biome </dev/null and rr plugins add ts </dev/null:

existing biome.json	before: rr jsc	after
2-space, no arrays	✖ biome.json (extends spread over 3 lines)	✔ rr check passes
2-space, inline files.includes	✖ biome.json (untouched array spread)	✔ rr check passes
fresh, then add biome --force	✖ biome.json rewritten by a no-op	✔ byte-identical, "No changes"
tabs (biome init)	✖ biome.json + run-run.config.mts	biome.json ✔ (tabs kept); run-run.config.mts and tsconfig.json still flagged
4-space, inline extends	✖ biome.json + run-run.config.mts	biome.json ✔; same two other files flagged

The tab and 4-space rows still fail on files this PR doesn't own: run-run.config.mts is written by the kernel's config-ast with 2 spaces, and tsconfig.json by ts-plugin's edit-json. Both are tracked separately; an ADR amending 004 is coming.

Regression guard: reverting only json-edit.ts fails 5 tests (json-edit, file-ops, 2× plugins integration). Reverting only the biome-plugin step fails its new unit and integration tests.

Merge Danger

Door: two-way

Blast Radius: small

• The cli change only skips writes that would have changed nothing.
• The biome step only runs on the patch path, and it falls back to the unformatted text.
• Known wart: the add log prints "Edited biome.json" twice, once per op.

🤖 Generated with Claude Code

https://claude.ai/code/session_01EZVC7xzzsEmByszmfff4u2

[changeset-bot]

🦋 Changeset detected

Latest commit: c4ac242

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@rrlab/biome-plugin	Patch
@rrlab/cli	Patch

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[vland-bot]

Preview release

Latest commit: c4ac242

Some packages have been released:

Package	Version	Install
@rrlab/biome-plugin	1.2.2-git-c4ac242.0	@rrlab/biome-plugin@1.2.2-git-c4ac242.0
@rrlab/cli	1.5.2-git-c4ac242.0	@rrlab/cli@1.5.2-git-c4ac242.0

Note

Use the PR number as tag to install any package. For instance:

pnpm add @rrlab/biome-plugin@pr-284