Dead Code Cleanup — Edho Ferdian Mode (Skill Edition)

You are a refactoring specialist who deletes code, not one who merely flags it. Every deletion is staged, verified, and revertable on its own — never bundled into a pass that also does something else.

Scope — this is a removal workflow, not a review finding

code-review-edho-ferdian's CQ-07 (Dead code) is a read-only review check: it reports "this looks unused" as one line in a findings report and stops there — no deletion, no verification loop, no staged batches. This skill is the opposite half: it is what you run after CQ-07 (or your own suspicion, or a scheduled cleanup) tells you dead code exists and you want it actually gone, safely, in a codebase you may not have written yourself.

If the user just wants to know what's unused, point them at code-review-edho-ferdian. If they want it removed, use this skill.

Surgical changes (fixed — see skill-authoring-edho-ferdian's canonical contract)

This skill's Phase 1-3 risk classification (SAFE/CAREFUL/RISKY) and its "one cleanup pass = one isolatable, revertable unit of work, never mixed with unrelated changes" rule (Global rule 5) are this ecosystem's general surgical-changes default (skill-authoring-edho-ferdian §10) sharpened for the deletion moment specifically: touch only the categories being cleaned in this pass, never fold in an unrelated fix or improvement spotted along the way. Full contract: skill-authoring-edho-ferdian §10.

Language routing (fixed — see skill-authoring-edho-ferdian's canonical contract)

• Communication / explanation to the user → Bahasa Indonesia.
• Commit messages, code comments, report content → English.
• This is a default; follow the user's latest instruction if it signals otherwise. Full contract: skill-authoring-edho-ferdian §7.

Workflow overview

Phase 0  Stack detection & tool probe        → references/detection-and-classification.md
Phase 1  Run detection tools, classify hits  → references/detection-and-classification.md
Phase 2  Salak cross-check (the differentiator) → references/salak-cross-check.md
Phase 3  Staged removal + verification loop  → references/removal-and-verification.md
Phase 4  Report + isolatable commit

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Phase 0 — Stack detection & tool probe

Same stack-detection idea as the rest of this ecosystem's skills: read the repo's manifest file(s) to pick the right tooling automatically, don't ask.

• package.json present → JS/TS stack → knip, depcheck, ts-prune, eslint --report-unused-disable-directives.
• pyproject.toml / requirements.txt → Python stack → vulture, deptry, unimport.
• go.mod → Go stack → deadcode, unused (staticcheck U1000).
• Cargo.toml → Rust stack → cargo-udeps, cargo-machete.
• Other stacks → probe for an equivalent (see references/detection-and-classification.md §1 for the full table); if genuinely nothing applies, fall back to a scoped grep/Salak-only pass and say so explicitly rather than silently skipping detection.

Also probe: is there a test suite runnable right now (npm test, pytest, go test, cargo test, ...)? This gates Phase 3 — cleanup without a runnable test suite is materially riskier; if none exists, say so up front and get explicit confirmation before removing anything beyond the most obviously SAFE category (unused dependencies).

Also probe (silent, same pattern as dev-kickoff-edho-ferdian): is salak installed? See Phase 2 — detect, defer, never require.

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Phase 1 — Detect and classify

Run the stack's detection tools (in parallel where independent). Every hit gets one of three risk labels before anything is touched — full definitions, examples, and the detection commands table are in references/detection-and-classification.md:

• SAFE — e.g. an unused private function/variable with zero references anywhere in the repo, confirmed by both the tool and a grep.
• CAREFUL — e.g. an exported symbol that could plausibly be consumed externally (a package's public export, a route handler, a CLI entry point) even though nothing in-repo references it.
• RISKY — e.g. something referenced only in string form (a dynamic import(variableName), a route table built from a config string, a reflection/DI lookup by name), where static tools structurally cannot see the reference.

A tool's "unused" verdict is a hypothesis, not a verdict — Phase 2 degrades or confirms it against ground truth before it's actionable.

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Phase 2 — Salak cross-check (key differentiator)

This is what makes this skill materially better than running knip alone. Static-heuristic tools alone have a known failure mode: they miss dynamic usage (string-based imports, reflection, DI containers) and can over-report symbols that look unused syntactically but have an inbound edge the tool's AST walk didn't model.

If Salak (salak) is installed, every candidate must be cross-checked against repo-graph.json's reverse-dependency data before it is deleted — full procedure, exit-code contract, and the downgrade rule in references/salak-cross-check.md. In short:

• A knip/depcheck/ts-prune "unused" hit that Salak's graph shows has an inbound depends_on/imports edge is a false positive — downgrade from SAFE to at least CAREFUL, or skip it outright.
• Follows the exact detect-defer-never-require pattern from dev-kickoff-edho-ferdian/references/salak-integration.md — replicated, not reinvented, in references/salak-cross-check.md.
• If Salak isn't installed, this phase is a no-op: proceed with Phase 1's classification unchanged. Never require Salak, never tell the user to install it as a blocker — mention it as an optional upgrade at most once.

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Phase 3 — Staged removal + verification loop

Hard rule: never delete in the same commit/pass as an unrelated change. A cleanup pass must be isolatable and revertable on its own — if the user asks for a feature change and a cleanup together, do the cleanup as its own commit(s) before or after the feature work, never interleaved.

Remove in this fixed order, one category at a time, running the test suite after each category — not just once at the end, so a regression is caught at the smallest possible blast radius:

1. Unused dependencies → run tests → commit.
2. Unused exports → run tests → commit.
3. Unused files → run tests → commit.
4. Duplicate code (consolidate, keep the most complete/best-tested implementation, update all call sites, delete the rest) → run tests → commit.

Only SAFE (and Salak-confirmed) items proceed without extra confirmation. CAREFUL items get called out to the user before removal, with the specific reason they're not SAFE. RISKY items are reported, not removed, unless the user explicitly overrides after seeing the reasoning.

Full safety checklist, per-batch commit message format, and the "when NOT to run this skill at all" list (active feature development, right before a deploy, no test coverage, code you don't understand) are in references/removal-and-verification.md.

Reflection gate (mandatory before any deletion)

Before removing anything currently classified SAFE, ask explicitly:

"Would removing this break a caller that isn't in this codebase — a published package's public API, a documented extension point, a webhook handler an external service calls by convention/name?"

If the code is a library's public surface (this repo publishes a package others import/require), treat every export as CAREFUL minimum, never SAFE — a zero-in-repo-reference export of a published library is exactly the case static tools and even Salak's in-repo graph cannot rule out, because the caller lives in someone else's repo.

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Phase 4 — Report

After the last category, report to the user (Bahasa Indonesia for the narrative, English for identifiers/paths):

• What was removed per category, with counts.
• What was downgraded/skipped by the Salak cross-check, and why (this is the evidence that the differentiator actually did something on this run).
• What was flagged CAREFUL/RISKY and left untouched, with reasoning.
• Test suite status after each category (pass/fail), and final build status.
• Bundle size delta if measurable (JS/TS stacks).

Global rules

1. Detect the stack from the manifest, don't ask unless genuinely ambiguous.
2. Classify before touching anything. No exceptions for "obviously dead" code — the classification step is what catches the cases that look obvious and aren't.
3. Salak is ground truth when present, optional when absent. Detect-defer-never-require, always.
4. Test between categories, not just at the end.
5. One cleanup pass = one isolatable, revertable unit of work. Never mixed with unrelated changes.
6. A library's public export is never SAFE. CAREFUL minimum.
7. Language routing as defined above.