code-editor-switch

Purpose

Use this skill to switch Finder/Open defaults for code, text, and config files to a new editor (for example Zed, VS Code, Cursor) using duti.

When to use

• Migrating from one editor to another on macOS.
• Standardizing file defaults for local repos and team machines.
• Fixing mismatched defaults for dotfiles and config files.

Non-negotiable rules

• Run this only on macOS.
• Prefer duti over direct LaunchServices plist edits.
• Apply both generic UTIs and concrete extensions/names.
• Keep public.data opt-in only (--apply-public-data).
• Verify with duti -x after applying mappings.

Workflow

1) Preflight

• Ensure duti exists:

- command -v duti >/dev/null || brew install duti

• Resolve bundle identifier for target editor:

- osascript -e 'id of app "Cursor"' - mdls -name kMDItemCFBundleIdentifier -raw "/Applications/Cursor.app"

2) Apply baseline mappings

• Run:

- bash "scripts/switch-code-editor.sh" --editor "Cursor"

• This applies:

- Core UTIs (public.text, public.plain-text, public.source-code, etc.) - Baseline code/config extensions (ts, tsx, js, json, yaml, sql, py, css, toml, mdx, etc.) - No-extension names like Dockerfile

3) Add project-driven coverage (preview first)

• Preview discovered tokens before applying (required):

- bash "scripts/discover-project-editor-tokens.sh" "$HOME/Developer/fmd-labs/viral-app" - bash "scripts/discover-project-editor-tokens.sh" "$HOME/Developer/fmd-labs/viral-app" | sed -n '1,120p'

• Optional safety check for obvious artifact noise:

- bash "scripts/discover-project-editor-tokens.sh" "$HOME/Developer/fmd-labs/viral-app" | rg '^(dep-|build-script-|bin$|a$|d$)'

• Only after preview/review, apply project scan:

- bash "scripts/switch-code-editor.sh" --editor "Cursor" --project "$HOME/Developer/fmd-labs/viral-app"

• If preview output is noisy, narrow --project to a cleaner subdirectory or expand excludes first.

4) Verify

• Check representative mappings:

- duti -x ts - duti -x tsx - duti -x env - duti -x gitignore - duti -x Dockerfile

• If Finder still opens old handlers, log out/in to refresh LaunchServices behavior.

5) Optional aggressive mode

• Only if explicitly requested:

- bash "scripts/switch-code-editor.sh" --editor "Cursor" --apply-public-data

• Warning: this can redirect many non-code files.

Known edge cases

• .ts can resolve to a non-code UTI on some systems; extension mapping is required.
• Dotfiles like .env.local are often matched by suffix (local) plus text UTIs.
• Some apps may reclaim specific extensions after updates/reinstalls.

Deliverables

When using this skill, always return:

• Target editor and resolved bundle ID.
• Exact script command used.
• Summary of UTI + token mappings applied.
• 3-5 verification checks (duti -x ...).

Progressive disclosure

Load only what is needed:

• references/coverage-from-viral-app.md for practical extension gaps.
• references/sources.md for source links and version checkpoints.
• scripts/discover-project-editor-tokens.sh for token discovery.
• scripts/switch-code-editor.sh for the full apply workflow.