simplify

name	simplify
description	Discovers incidental complexity, duplication, and dead code in a codebase and produces a ranked, behavior-preserving reduction plan — optionally applying safe changes. Dispatches four parallel read-only discovery lenses (clone detection, dead code, complexity hotspots, wrong abstraction), synthesizes into a prioritized reduction plan, and gates apply mode behind /refactor and a hard test check.
argument-hint	[target] [--apply] [--all]
context	load

Sub-agent contract

/contract

Overview

/simplify is a discovery-and-prioritization skill, not a correctness auditor (that is /review's job) and not a blind executor (that is /refactor's job). It answers: what incidental complexity, duplication, and dead weight exists in this code, and what is safe to remove? Default mode is read-only: a ranked reduction plan is emitted but nothing is changed. Writes only happen when --apply is explicitly passed.

Scope is diff-bounded by default (git diff origin/main, or working-tree/HEAD if no remote). Pass --all for a whole-repo sweep (where duplication and dead-code analysis pay off most). Pass an explicit [target] path or PR reference to override both. Code with no test coverage is safe to analyze but must never be auto-applied — the skill surfaces that gap and recommends /simplify [target] --all after adding tests, or produces the plan and stops.

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Argument parsing

Argument	Effect
(none)	Scope = git diff origin/main (working-tree fallback)
[target]	Explicit path, glob, or PR ref
--all	Whole-repo sweep; excludes node_modules/, dist/, generated files
--apply	Opt-in write mode; default is read-only plan

Parse arguments before dispatching Wave 1. Resolve scope to a concrete file list or diff stat and attach it to every sub-agent prompt.

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Wave 1 — Parallel discovery (read-only)

Dispatch all four lenses simultaneously as research-agent sub-agents. All are strictly read-only — no writes, no installs that modify package.json. Optional tooling (jscpd, knip) is an accelerant only; degrade to grep/structural reasoning when absent or network-gated.

(a) Duplication / clone detection

Find exact and near-duplicate logic blocks across modules within scope. Optionally seed with:

npx jscpd <scope> --reporters json --silent

If jscpd is absent, use grep for literal repetition and structural reasoning for semantic clones. Output: clone clusters with file:line ranges, estimated token overlap, and a suggested extraction site.

(b) Dead code / unused exports

Find module-graph-dead exports, unreachable branches, and obsolete feature flags — beyond what tsc --noEmit --noUnusedLocals already catches. Optionally seed with:

npx knip --reporter json

MANDATORY GROUNDING: every "X is unused/dead" claim MUST carry:

1. A file:line citation for the symbol.
2. A structural evidence path — who would import it, and why nothing does.

Dynamic imports, reflection, string-keyed access, and barrel re-exports are common false-positive vectors. Never assert dead code without grounding. Flag uncertain cases as POSSIBLE-DEAD rather than DEAD.

(c) Complexity hotspots

Identify over-long functions (>40 lines), deep nesting (>3 levels), boolean-flag parameters, primitive obsession, and sprawling switch/if chains. The target repo has NO ESLint — this lens is pure agent reasoning over the code, not lint output. Rank by cyclomatic complexity estimate × call-site frequency. Output: hotspot list with file:line, smell label, and a plain-language refactor suggestion.

(d) Reuse / wrong-abstraction-level

Find code that reimplements an existing helper, sits at the wrong layer (leaky abstraction, unnecessary wrapper), or is a thin pass-through with no added value. Cross-reference the project's existing utilities before flagging. Output: reuse candidates with file:line, what existing construct could replace them, and estimated call-site count.

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Synthesis — inline, after Wave 1

1. Dedup: one site often trips multiple lenses. Merge duplicate entries; annotate each with the lens(es) that flagged it.
2. SANDI-METZ WRONG-ABSTRACTION GUARD: flag but do NOT propose collapsing two code paths if unifying them requires introducing a new boolean/flag parameter. Record these as "defer — duplication is cheaper than the wrong abstraction" with an explanation.
3. Rank by impact × safety:
   • HIGH IMPACT: multi-site duplication, provably dead exports, complexity hotspots at high call frequency.
   • LOW RISK: purely local changes, full test coverage, no public API surface.
   • Deprioritize: single-use private helpers, style preferences, anything touching uncovered code.
4. Emit the reduction plan — one row per finding:

#	Location (file:line)	Smell	Proposed simplification	Risk note	Behavior-preservation note

5. Append a Coverage gate summary: list files in scope with no test coverage where apply was requested — recommend tests first.

In default (read-only) mode: STOP here. Print the plan and exit.

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Wave 2 — Gated apply (only when --apply is passed)

Before any write, verify the test suite is green:

pnpm lint && pnpm test

If the gate is red before any change, abort apply and report. Do not attempt to fix pre-existing failures.

Delegation decision (per ranked item, high-to-low):

• Multi-site mechanical changes (extract duplicated block into a shared helper used at N≥2 sites): delegate to /refactor if available. /refactor handles DAG-layered, worktree-isolated parallel application with a hard test gate at each layer boundary and a behavioral diff. Pass the reduction plan item as the refactor spec.
• /refactor NOT available, OR single-site local simplifications: apply directly inside a git worktree. One change at a time; run pnpm lint && pnpm test after each. On regression → route to /diagnose; revert the change; continue with remaining items.
• Items touching uncovered code: skip apply, preserve in plan output as "plan-only — no test coverage".

On full success, chain to /ship for commit + PR.

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Guardrails

• Behavior-preserving only — never change observable behavior under the guise of cleanup.
• Exclude node_modules/, dist/, vendored code, and auto-generated files from all analysis.
• Optional tooling (jscpd, knip) must not modify package.json or lock files — use npx with no persistent side effects.
• Diff-scoped by default; whole-repo only on --all — avoids signal-drowning noise on large codebases.
• Max 3 apply-layer retries per item before skipping and continuing.

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Failure modes to surface explicitly

Failure mode	Mitigation
Over-DRYing / wrong abstraction	Sandi-Metz guard (see Synthesis step 2)
False dead-code positives	Mandatory grounding rule on lens (b)
Behavior change disguised as cleanup	Pre/post test gate; worktree isolation
Scope creep on large repos	Diff-scope default; --all is explicit opt-in

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Chains to

• /refactor — multi-site mechanical apply
• /ship — commit + PR after successful apply
• /diagnose — when an applied simplification breaks a test