simplicity-hunter-ts

name	simplicity-hunter-ts
description	Audit TypeScript code for unnecessary structural complexity — duplication, avoidable abstractions, dead logic paths, flag-heavy APIs, deep nesting, mixed concerns, and coexisting abstraction generations left behind by unfinished migrations. Recommends the simplest shape that preserves intended behavior. Use when: reviewing TypeScript code for over-engineering, reducing complexity after prototyping, enforcing reuse over addition, simplifying before a refactor, or auditing a codebase after a framework or library migration.
disable-model-invocation	true

Simplicity Hunter

Audit TypeScript code for structural complexity — places where logic is duplicated, abstractions don't earn their keep, control flow is deeper than it needs to be, or concerns are mixed. The goal: the simplest code that preserves intended behavior.

When to Use

• Reviewing new code for over-engineering or unnecessary indirection
• Reducing complexity after initial prototyping
• Enforcing reuse over addition before merging
• Preparing code for long-term maintainability
• Deduplicating logic across production modules

Core Principles

1. Default to delete. The best simplification is removal. If code can be deleted without changing behavior, delete it. If it can be replaced by an existing helper, replace it.

2. One canonical path. When two implementations do the same thing, pick one and remove the other. Avoid "shared helper + keep both paths" unless required by genuinely different consumers. When the two paths are near-identical, the remedy is deletion; when they are different designs that are both in use, the finding is the unfinished migration itself, and the remedy is a retirement plan naming the stratum that survives.

3. Abstractions must earn their place. Reject new wrappers, managers, and factories unless they reduce total complexity through reuse. An abstraction that serves one call site is indirection, not simplification.

4. Flags are complexity multipliers. Each boolean parameter doubles the logic paths. Prefer one linear flow; if a flag is unavoidable, require sharp naming and a removal plan.

5. Inline the trivial. Pass-through wrappers, single-use helpers, and indirection layers that add no logic should be inlined. Measure value by what the wrapper adds, not by what it hides.

6. Separate concerns, don't mix them. A function that builds data AND formats output AND logs errors has three reasons to change. Split into focused helpers with intent-revealing names.

7. Flatten, don't nest. Deep nesting (3+ levels) signals mixed concerns or missing early returns. Use guard clauses and early returns to keep the main path at low indentation.

What to Hunt

1. Duplication

Repeated logic across production functions and modules. (Duplication within test code — copied setup, repeated assertion blocks — is test-hunter's finding; do not flag it here.)

Signals:

• Two functions with near-identical bodies differing only in a value or branch
• Multiple implementations of the same algorithm

Action: Choose one canonical implementation; delete the rest; extract shared logic only if it serves 2+ genuine consumers.

2. Unnecessary Abstractions

Wrappers, managers, registries, or factories that serve a single call site or add no logic.

Signals:

• A class/function that delegates to one other function with no transformation
• A "manager" that wraps a single resource
• A factory that returns only one type
• An interface with a single implementation and no plan for more

Action: Inline the abstraction. If it exists for testability, note that and keep if justified.

3. Dead Code Paths

Unreachable branches, unused internal helpers, stale feature flags, and leftover alternate implementations.

Signals:

• if branches that can never be true given the input types or call sites
• Internal helper functions with zero call sites (exported dead symbols are boundary-hunter territory)
• Feature flags that are always on/off
• Commented-out alternate implementations

Action: Delete. If uncertain, flag with evidence of zero usage.

4. Over-Parameterized APIs

Functions with many optional parameters, boolean flags, or configuration objects that create a combinatorial explosion.

Signals:

• 4+ parameters, especially booleans
• Functions with if (opts.X) branches for most parameters
• Configuration objects where most fields are optional and defaulted

Action: Split into focused functions per use case, or reduce to the parameters actually used by callers.

5. Mixed Concerns

Single functions or classes that handle multiple unrelated responsibilities.

Signals:

• A function that fetches data AND transforms it AND renders output
• A function or module body that mixes abstraction levels (raw I/O plumbing interleaved with domain decisions)
• Long functions (50+ lines) with distinct logical sections separated by blank lines or comments

(Responsibility analysis of classes — methods spanning concerns, multiple reasons to change — is solid-hunter's SRP territory; keep this signal at function/module level.)

Action: Extract each concern into a named helper. The parent function becomes a coordinator.

6. Complex Control Flow

Deep nesting, nested ternaries, long if/else if chains, convoluted loops, and unflattened async control flow.

Signals:

• 3+ levels of nesting
• Nested ternaries (a ? b ? c : d : e)
• if/else if chains with 4+ branches
• Loop bodies with embedded conditionals
• 3+ levels of nested callbacks (Node.js-style (err, result) => { ... })
• .then().then().then() chains longer than 3 steps, or nested .then() "promise pyramids"
• Mixing callbacks and promises in the same function
• Error handling scattered across multiple .catch() blocks where a single try/catch would do

Action: Flatten with guard clauses and early returns. Replace nested ternaries with explicit conditionals. Extract loop bodies into named functions when complex. Convert callback pyramids and long .then() chains to async/await with try/catch; use Promise.all()/Promise.allSettled() for genuinely parallel work.

7. Coexisting Generations (Lava Layers)

Two or more live, structurally different solutions to the same concern, left behind by a migration that was started and never finished. Each generation hardens where it stopped: new code picks whichever stratum its author happened to know about, and every reader has to learn all of them.

The test that makes this a finding: every stratum must be live. If the older stratum has no call sites, it is dead code (§3) — delete it. If the two bodies are near-identical, it is duplication (§1) — pick one and delete the rest. This category covers only the case where the designs genuinely differ and all of them are in use, because that is the only case whose remedy is a migration rather than a deletion.

Signals:

• v1//v2/, legacy/, old/, new/ directories, or *Legacy/*V2/*Old/*Deprecated symbols, where the older path still has importers
• @deprecated JSDoc on symbols that still have live import sites
• Overlapping dependencies in package.json that solve one concern — axios + node-fetch + got, moment + date-fns + dayjs, jest + vitest, two state or validation libraries
• Two or more role abstractions for the same concept, all still constructed somewhere: UserRepository + UserStore + UserDao
• Environment- or config-selected parallel implementations where both branches are reachable (a flag that is always on or always off is a stale flag — §3)

Action: Report the strata, name the one that should survive — git recency and the stratum newer call sites choose usually settle it — and recommend a retirement plan for the rest: which call sites move, and which stratum gets deleted once empty. Never recommend a rewrite; the surviving generation is already written.

Audit Workflow

Phase 1: Gain Context

1. Resolve audit surface. The prompt may specify the scope as:

   • Diff: files changed relative to the base branch — committed, staged, unstaged, and untracked
   • Path: specific files, folders, or layers
   • Codebase: the entire project (the default when unspecified; set SCOPE=.)

   Party mode: when the orchestrator supplies a scope snapshot (a resolved file list), use it verbatim and do not re-resolve. The resolution below applies to standalone runs only.

   For diff mode, resolve fail-closed:

   BASE=$(git symbolic-ref refs/remotes/origin/HEAD 2>/dev/null | sed 's@^refs/remotes/@@')
   if [ -z "$BASE" ]; then
     for b in origin/main origin/master main master; do
       git rev-parse -q --verify "$b" >/dev/null && BASE=$b && break
     done
   fi
   # If BASE is still empty: STOP. Ask for an explicit base. Do not continue.
   
   SCOPE=$( { git diff --name-only --diff-filter=d "$BASE"...HEAD;
              git diff --name-only --diff-filter=d HEAD;
              git ls-files --others --exclude-standard; } | sort -u )
   DELETED=$( { git diff --name-only --diff-filter=D "$BASE"...HEAD;
                git diff --name-only --diff-filter=D HEAD; } | sort -u )
   

   If $SCOPE is empty, run no scans: write the report with "Audit completed: 0 findings — empty diff scope", listing $DELETED under "Deleted in diff" if non-empty, and stop. If the resolved surface exceeds what can be read within the context budget, report the file count and ask to narrow or chunk.

   Two surfaces. Findings are reported only against the target scope ($SCOPE) — every finding anchors (file:line) there. Related files may still be read as context: when judging duplication, search the whole project for the canonical implementation and existing helpers.

2. Understand the project's existing helpers, utilities, and conventions.

3. Note any stated design decisions (e.g., intentional duplication for performance).

Phase 2: Scan for Complexity Signals

Run every scan against the target scope (SCOPE=. in codebase mode).

# Production-scan exclusions: dependencies, build output, generated code, tests
# (test-code complexity and duplication belong to test-hunter)
EXCLUDE='--glob !**/node_modules/** --glob !**/dist/** --glob !**/*.generated.* --glob !**/__generated__/** --glob !**/*.g.ts --glob !**/generated/** --glob !**/*.test.* --glob !**/*.spec.* --glob !**/*.e2e.* --glob !**/__tests__/**'

# Deep nesting (4+ indentation levels, 2-space indent)
rg '^\s{8,}\S' --type ts $EXCLUDE -- $SCOPE

# Boolean parameters
rg --pcre2 '\w+\s*[?:]?\s*:\s*boolean' --type ts $EXCLUDE -- $SCOPE

# Functions with many parameters (declarations, arrow functions, methods)
rg --pcre2 'function\s+\w+\s*\([^)]{80,}\)' --type ts $EXCLUDE -- $SCOPE
rg --pcre2 '(?:const|let)\s+\w+\s*=\s*(?:async\s+)?\([^)]{80,}\)\s*(?:=>|:)' --type ts $EXCLUDE -- $SCOPE
rg --pcre2 '^\s+\w+\s*\([^)]{80,}\)\s*[:{]' --type ts $EXCLUDE -- $SCOPE

# Nested ternaries
rg --pcre2 '\?[^:]+\?' --type ts $EXCLUDE -- $SCOPE

# Callback pyramids and long .then() chains
rg --pcre2 '\.then\([^)]*\)\s*\.then\([^)]*\)\s*\.then' --type ts $EXCLUDE -- $SCOPE

Phase 3: Scan for Duplication

1. Identify repeated patterns across files using targeted searches.
2. Look for multiple implementations of the same logic with minor variations.

Phase 4: Scan for Coexisting Generations — codebase and path scope only

Scope gate. This phase needs a view of the whole repository:

• Codebase scope — run it fully.
• Path scope — run it. Findings anchor inside the target path; the rest of the repository is read as context to establish what the competing generations are.
• Diff scope — skip it. Coexisting strata are invisible through a changed-file window: the scan would either find nothing or anchor a whole-stratum claim to an arbitrary changed line. Record the skip in the report's Scope section — do not omit it silently, and do not substitute a narrower diff-only heuristic.

The scans below read the whole tree regardless of scope, and the dependency check reads package.json, so Phase 2's production $EXCLUDE profile does not apply here. Pass an explicit path to every rg invocation: with no path argument, rg blocks reading stdin in a non-interactive shell.

1. Read package.json and list dependencies that solve the same concern (HTTP, dates, state, validation, test runners). Two test runners or two HTTP clients is the cheapest high-precision signal in this category, and it needs no pattern matching.

2. Find generation-named symbols and paths:

   rg -l --type ts 'Legacy|Deprecated|V1|V2' --glob '!**/node_modules/**' --glob '!**/dist/**' .
   find . -type d \( -name 'v[0-9]*' -o -name legacy -o -name old -o -name new \) \
     -not -path '*/node_modules/*' -not -path './dist/*'
   

3. Find deprecation markers:

   rg -n --type ts '@deprecated' --glob '!**/node_modules/**' --glob '!**/dist/**' .
   

4. Confirm liveness for every candidate stratum. Search the whole project for its import and construction sites. A stratum with zero sites is a §3 finding, not a §7 one — reclassify it and move on.

5. Establish which generation is current where the evidence allows: git log -1 --format=%as -- <path> per stratum, and which stratum the most recently added call sites use.

These scans nominate candidates only. A name containing V2 proves nothing on its own; the finding is the pair of live strata, not the label.

Phase 5: Evaluate Each Finding

For each complexity signal, determine:

• Is this genuinely unnecessary, or does it serve a purpose?
• What is the simplest change that eliminates it?
• Does the simplification break any public API? If so, flag but default to follow-up.
• For a coexisting-generations candidate: are all strata live, and do the designs actually differ? If only one is live, reclassify to §3; if the bodies are near-identical, reclassify to §1.

Phase 6: Produce Report

Output Format

Save as YYYY-MM-DD-simplicity-hunter-audit-{model-name}.md — {model-name} is the executing model's short name (e.g. fable-5) — in the project's docs folder (or project root if no docs folder exists). If the caller specifies an output path (e.g. the party-hunter orchestrator), it overrides this default.

Severity levels, used for per-finding labels and the Recommendations grouping:

• Critical — exploitable now, causes data loss, or breaks behavior on production paths.
• High — a defect with likely user-visible, security, or reliability impact if left unaddressed.
• Medium — correctness or maintainability risk without imminent impact.
• Low — hygiene; no behavioral risk.

# Simplicity Hunter Audit — {date}

## Scope

- Surface: {diff / path / codebase}
- Files: {count or list}
- Exclusions: {list}
- {Deleted in diff: {list} — only for diff scope with deletions}
- {Coexisting generations: skipped — requires codebase or path scope — only for diff scope}
- Audit completed: {N} findings

## Findings

### Duplication

| # | Locations | Description | Action |
| - | --------- | ----------- | ------ |
| 1 | file:line, file:line | Near-identical validation logic | Deduplicate into shared helper |

### Unnecessary Abstractions

| # | Location | Abstraction | Consumers | Action |
| - | -------- | ----------- | --------- | ------ |
| 1 | file:line | `ConfigManager` class | 1 | Inline |

### Dead Code Paths

| # | Location | Code | Evidence | Action |
| - | -------- | ---- | -------- | ------ |
| 1 | file:line | `legacyHandler()` | 0 internal call sites | Delete |

### Over-Parameterized APIs

| # | Location | Function | Params | Action |
| - | -------- | -------- | ------ | ------ |
| 1 | file:line | `render(a, b, c, d, e)` | 5 (3 booleans) | Split by use case |

### Mixed Concerns

| # | Location | Function | Concerns | Action |
| - | -------- | -------- | -------- | ------ |
| 1 | file:line | `processOrder()` | fetch + transform + log | Extract into 3 helpers |

### Complex Control Flow

| # | Location | Pattern | Depth | Action |
| - | -------- | ------- | ----- | ------ |
| 1 | file:line | Nested ternary | 3 | Replace with conditional |

### Coexisting Generations

| # | Concern | Strata | Live evidence | Current | Action |
| - | ------- | ------ | ------------- | ------- | ------ |
| 1 | HTTP client | `src/api/http.ts:12` (axios), `src/lib/fetchJson.ts:8` (node-fetch) | 14 vs 3 import sites | axios — newer call sites | Move the 3 sites to `http.ts`; drop `node-fetch` |

## Recommendations (Priority Order)

1. **High**: {high-impact duplication, dead code with confidence, generations whose behavior diverges}
2. **Medium**: {unnecessary abstractions, over-parameterized APIs, generations with equivalent behavior}
3. **Low**: {control flow improvements, concern separation}

(Structural complexity is rarely Critical on its own; use Critical only when a duplicated or dead path is actively producing wrong behavior in production. Coexisting generations are Medium by default; raise to High when the strata behave differently — two HTTP clients with different retry and timeout policies, two validators enforcing different rules — because that is a live behavioral divergence, not only maintenance debt.)

Operating Constraints

• No code edits. This skill produces an audit report only. Implementation is a separate step.
• No empty finding sections. Include only categories with findings. Omit a heading, table, or list entirely when it would contain zero items — do not include empty tables, placeholder subsections, or negative statements like "no dead exports", "none found", or "no issues". Execution status is exempt: the "Audit completed: N findings" line, and the coexisting-generations skip line when the scope is a diff, are always present in the Scope section even at zero findings.
• Scope: structural complexity in production code only. If a finding doesn't answer "is this simpler than it could be?", it belongs to another hunter — do not flag it here. Test-code duplication and setup bloat belong to test-hunter; class-level responsibility analysis belongs to solid-hunter.
• Coexisting generations: adjacent categories. Shotgun surgery — one logical change spreading across many modules — is smell-hunter's; §7 is the inverse, many generations stacked on one concern. An external dependency with no wrapper at all is boundary-hunter's Missing Abstraction Over Externals; two wrappers of different vintage are §7. A feature flag that is always on or off is a stale flag (§3); a flag whose branches are both live with no removal plan is §7.
• Retire, don't rewrite. A coexisting-generations finding moves call sites onto a stratum that already exists and deletes the others. Never recommend a third generation.
• Evidence required. Every finding must cite file/path.ext:line with the exact code. A coexisting-generations finding cites file:line for every stratum, plus a live import or call site for each — a stratum whose liveness is not shown is not part of the finding.
• Reuse over addition. When recommending a fix, prefer existing helpers or deletion over new code.
• Preserve behavior. Never recommend changes that alter what the code does, only how it's structured.
• Pragmatism. Not every abstraction is wrong. Flag, assess, and acknowledge intentional complexity. If a simplification breaks public APIs or backwards compatibility, call it out and default to follow-up.