Promote Component

promote-component — Rule of Three automation

Contract

See references/contracts.md (vendored from dev-flow). Key facts:

• Reads <project-root>/.workflow/meta.json#stack.framework (must be "next", "expo-rn", or "monorepo").
• Reads meta.json#stack.route_groups (optional, helps detect the target level).
• Modifies code in <project-root>/ (or <project-root>/apps/<web|mobile>/ for monorepo).
• Does NOT modify meta.json#phase. Appends to meta.json#history.
• Always idempotent: re-running the scan reports the same candidates; re-running a promote on an already-promoted component does nothing.

When this skill applies

• User says "scan promotion candidates" / "scansiona candidati promozione" → run the scan.
• User says "promote " / "promovi " → execute the move.
• The user is reviewing the codebase after a feature lands and wants to clean up duplication.

Orchestrator does NOT route here automatically — invoked on demand.

Knowledge dependencies

• composition-patterns-guide/SKILL.md — the 7 Vercel composition rules + our colocation rules.
• references/colocation-rules.md — the canonical Rule of Three + L0/L1/L2 spec.

Web vs mobile targets (read this first)

Next.js App Router supports _-prefixed private folders — app/<route>/_components/ is a valid non-routable convention there. Expo Router does not: every file under app/ (aside from a short reserved list) becomes a real route, so app/<route>/_components/ would create a ghost route on mobile, not a private folder. Settled upstream, not pending: the request (expo/expo#44696) was closed won't fix on 2026-06-01 — Expo Router wants components outside app/ by design. Confirmed mechanically at expo-router@57.0.16: no underscore rule in the route scanner. Treat mobile app/ as routes-only, permanently. See references/colocation-rules.md.

Consequently this skill uses different scan/target paths per platform — see references/colocation-rules.md for the full model and rationale. Summary:

Everything below is written generically ("the platform's _components/-or-components/<feature>/ root") — substitute per the table above. The scripts (scripts/scan_promotion.py, scripts/promote.py) branch on meta.json#stack.framework automatically.

Workflow — scan mode

Step 1 — Detect framework + cwd

Read meta.json#stack.framework:

• "next" → cwd = project root, scan app/**/_components/.
• "expo-rn" → cwd = project root, scan components/<feature>/ (excluding components/{ui,theme,shared}).
• "monorepo" → scan apps/web/ with the web rules and apps/mobile/ with the mobile rules, separately. Print two tables.

Step 2 — Find every promotion candidate

Web:

find app -type d -name "_components" -exec ls -1 {} \;

For each .tsx file in _components/, record component name, source path (e.g., app/(app)/posts/_components/PostCard.tsx), and current level (L0: under a leaf route, L1: under app/(group)/_components/).

Mobile:

find components -mindepth 2 -maxdepth 2 -name "*.tsx" | grep -vE '/(ui|theme|shared)/'

For each match, record component name, source path (e.g., components/posts/PostCard.tsx), and which feature folder(s) hold a copy of that name (duplicates across feature folders are the mobile promotion signal — see Step 4).

Step 3 — Count usages

For every component, grep the codebase for imports referencing its file path or filename (both platforms):

grep -rln "from .*['\"].*PostCard['\"]" app/ components/ --include="*.tsx" --include="*.ts"

Count distinct import sites (deduplicate by file).

Step 4 — Compute suggestions per Rule of Three

Web:

Mobile (mobile has no separate L1 path — see colocation-rules.md):

Step 5 — Print the report

Promotion candidates in apps/web/ (next):

| Component                  | Usages | Current level | Suggestion                              |
|----------------------------|--------|---------------|------------------------------------------|
| PostCard                   | 3      | L0            | Promote to L1 — app/(app)/_components/   |
| UserAvatar                 | 4      | L0            | Promote to L2 — components/shared/user/  |
| BillingSummary             | 2      | L0            | Wait the 3rd use                         |
| PricingTable               | 5      | L0            | Promote to L2 — components/shared/billing/ |

Promotion candidates in apps/mobile/ (expo-rn):

| Component                  | Usages | Current level | Suggestion                                |
|----------------------------|--------|---------------|--------------------------------------------|
| PostCard                   | 3      | L0            | Promote to L2 — components/shared/post/    |
| SettingsRow                | 2      | L0            | Wait the 3rd use                           |

Ask the user: "Vuoi promuoverne alcuni? (Y/n, oppure dimmi quali)".

Workflow — promote <Component> mode

Step 1 — Locate the source file

Web: find the file matching <Component> under app/**/_components/. Mobile: find the file matching <Component> under components/<feature>/ (excluding components/{ui,theme,shared}).

If multiple matches (e.g., two copies at L0):

• The "canonical" copy is the older / most-complete one.
• Diff the two; flag any divergence to the user for resolution.

Step 2 — Determine target level

If invoked without an explicit target, recompute from usage/copy distribution:

• Web: same route group, 3+ usages → L1: app/(group)/_components/<Component>.tsx. Different groups, 3+ usages → L2: components/shared/<dominio>/<Component>.tsx.
• Mobile: copies in 3+ feature folders reconcilable to one domain → merge into components/<feature>/<Component>.tsx (no move, dedupe only). Copies spanning different business domains → L2: components/shared/<dominio>/<Component>.tsx.

Ask the user for <dominio> if not obvious (either platform). If an explicit target is provided ("promote PostCard to L2 in components/shared/post/"), honor it.

Step 3 — Move the file

Web:

# L0 → L1 (same group)
git mv app/(app)/posts/_components/PostCard.tsx app/(app)/_components/PostCard.tsx

# L0 → L2 (cross-group)
mkdir -p components/shared/post
git mv app/(app)/posts/_components/PostCard.tsx components/shared/post/PostCard.tsx

Mobile (never touches app/ — components never live there):

# Dedupe (3rd use reconciled to one feature) — keep the canonical copy in place, remove the others
rm components/profile/PostCard.tsx   # duplicate removed, canonical stays at components/posts/PostCard.tsx

# L0 → L2 (cross-domain)
mkdir -p components/shared/post
git mv components/posts/PostCard.tsx components/shared/post/PostCard.tsx

If duplicates existed at L0 (the "2 copies" case), also rm them (both platforms).

Step 4 — Update all imports

Scan all .tsx / .ts files in app/ and components/, find imports referencing the OLD path or filename, rewrite to the NEW path. Applies identically on both platforms — the import-rewrite step never assumes a platform-specific path shape.

Pattern types:

• Web: from "@/app/(app)/posts/_components/PostCard" → from "@/components/shared/post/PostCard"
• Mobile: from "@/components/posts/PostCard" → from "@/components/shared/post/PostCard"
• from "./PostCard" (siblings) → resolve to absolute, then rewrite
• from "../PostCard" (parent) → idem

Use a TypeScript-aware import rewrite (e.g., ts-morph Python equivalent via jscodeshift or simple regex with care).

Step 5 — Verify with tsc

npx tsc --noEmit

Must pass. If it fails:

1. Inspect the error: usually a path that wasn't rewritten.
2. Fix it manually.
3. Re-verify.

If still failing after 2 attempts, ROLLBACK the move (git restore) and report to the user.

Step 6 — Commit + history

git add -A
git commit -m "refactor: promote <Component> from <old-level> to <new-level>"

Append to meta.json#history:

{
  "skill": "promote-component",
  "ran_at": "<iso>",
  "inputs": {"component": "PostCard", "from": "L0 (3 sites)", "to": "L2", "domain": "post"},
  "outputs": {"new_path": "components/shared/post/PostCard.tsx", "imports_updated": 3}
}

Common anti-patterns (NEVER do)

• ❌ Promote at the 2nd use — wait the 3rd. The premature abstraction is more expensive than the duplicate.
• ❌ Move without rewriting imports — broken project.
• ❌ Promote a compound component piece by piece — the whole compound moves together, always.
• ❌ Use generic domain names (shared/common/, shared/misc/) — use the business domain.
• ❌ Promote across route groups WITHOUT going to L2 — if 2+ groups use it, it MUST live in components/shared/.
• ❌ Skip the tsc verification — silent broken imports propagate.

Updating meta.json (recommended pattern)

python3 .../dev-flow/scripts/update_meta.py <project-root> append-history \
    --skill 'promote-component' --inputs '{"component": "<X>"}' --outputs '{"new_path": "<path>"}'

Sources

• Spec: docs/superpowers/specs/2026-06-06-folder-structure-refactor.md
• Sandi Metz, "The Wrong Abstraction" (2016): https://sandimetz.com/blog/2016/1/20/the-wrong-abstraction
• "Rule of Three" pattern: documented in "The Pragmatic Programmer" + multiple refactoring books.