Zipper Tools

ESLint Migration Guides

Why multiple legacy ESLint config sources block flat config migration

If a repo has more than one legacy ESLint config source, the deterministic migration path should stop for manual review.

Start here

The safe first move

Keep multiple legacy ESLint config sources in manual review. The first job is deciding which source is authoritative before generating a flat config bridge.

Stop before automation when: Choosing the real source of truth. Merging overlapping rules and ignores.

Target shape

# manual review required
# choose the authoritative legacy config source before migration

Repo fit check

Want to know if your repo has this pattern?

Run the matching scanner locally first. The fit-report add-on is not listed for this proof-only product yet, so use the proof page and scanner output before treating it as a purchase candidate.

  • Local scan; no repository upload.
  • Supported findings are separated from manual-review findings.
  • Buy only when the repeated pattern is worth automating.
Run the static-config scan View example report See when to buy 
Example scan summary
supported_findings: 38
manual_review_findings: 6
files_uploaded: 0
confidence: reviewable

Why this page exists

Why multiple legacy ESLint config sources block flat config migration

One static config source is a fit. Multiple overlapping sources are not a clean automatic migration target.

Direct answer

What changes

Keep multiple legacy ESLint config sources in manual review. The first job is deciding which source is authoritative before generating a flat config bridge.

Example

Before and after

Before

.eslintrc.json
package.json#eslintConfig

After

# manual review required
# choose the authoritative legacy config source before migration

Decision path

If this repeats across the repo, open the evaluation pages next.

This product exists for the static-config subset. It does not pretend to evaluate JS config logic.

  • Teams migrating static .eslintrc JSON or YAML configs.
  • Repos that still store eslintConfig inside package.json.
  • The fit-report add-on is not listed for this proof-only product yet; use the proof page and scanner output before treating this as purchasable.

Before checkout

Product fit, proof, and price should all be one click away.

Current listed price is not published on the pricing page yet.

Typical symptoms

  • The repo has both .eslintrc data and package.json eslintConfig.
  • Teams want one pass that qualifies repo fit before generating anything.
  • Reviewers need a clear reason why the flat-config pack stopped.

What the product covers

  • Explicit multiple-config-sources findings.
  • Cross-links to the supported .eslintrc and package.json pages.
  • Repo-fit guidance before buying the flat-config pack.

Manual-review boundary

  • Choosing the real source of truth.
  • Merging overlapping rules and ignores.
  • Repos that also already have eslint.config.* files.

Keep the migration narrow

Use the exact-problem guides as a triage layer, then decide whether the repo is inside the supported subset.

FAQ

Fast answers before you decide

What is the safest fix for multiple ESLint config sources flat config migration?

Keep multiple legacy ESLint config sources in manual review. The first job is deciding which source is authoritative before generating a flat config bridge.

Can multiple ESLint config sources flat config migration be automated?

Automate only the supported subset: Explicit multiple-config-sources findings. Cross-links to the supported .eslintrc and package.json pages. Repo-fit guidance before buying the flat-config pack. Keep these cases in manual review: Choosing the real source of truth. Merging overlapping rules and ignores. Repos that also already have eslint.config.* files.

When should I buy ESLint Flat Config Migration Cleanup Pack?

Use ESLint Flat Config Migration Cleanup Pack only when this pattern repeats across enough files that manual cleanup is still costly. Run the public scan or read the proof first. The fit-report add-on is not listed for this proof-only product yet; if unsupported findings dominate, keep the work manual.