ln-624-code-maintainability-hotspot-auditor

name	ln-624-code-maintainability-hotspot-auditor
description	Checks local maintainability hotspots: complexity, long methods, god modules, signatures, algorithms, and constants. Also flags identifier drift across API/DTO/DB layers. Use when auditing code hotspots.
allowed-tools	Read, Grep, Glob, Bash, mcp__hex-graph__audit_workspace, mcp__hex-graph__analyze_architecture, mcp__hex-line__read_file, mcp__hex-line__grep_search, mcp__hex-line__outline
license	MIT

Paths: File paths (references/, ../ln-*) are relative to this skill directory.

Code Maintainability Hotspot Auditor (L3 Worker)

Type: L3 Worker

Specialized worker auditing local code hotspots that are hard to read, change, or reason about.

Purpose & Scope

• Audit code maintainability hotspots (priority: medium)
• Check complexity metrics, method signature quality, local algorithmic efficiency, constants management, identifier consistency across layers
• Emit REFACTOR_HOTSPOT, SIMPLIFY_SIGNATURE, EXTRACT_CONSTANT, or UNIFY_IDENTIFIER
• Return structured findings with severity, location, effort, recommendations
• Calculate compliance score (X/10) for Code Quality category

Inputs

MANDATORY READ: Load references/audit_worker_core_contract.md. Tool policy: follow host AGENTS.md MCP preferences; load references/mcp_tool_preferences.md and references/mcp_integration_patterns.md only when host policy is absent or MCP behavior is unclear.

Receives contextStore with: tech_stack, best_practices, principles, codebase_root, output_dir.

Domain-aware: Supports domain_mode + current_domain (see audit_output_schema.md#domain-aware-worker-output).

Workflow

Detection policy: use two-layer detection (candidate scan, then context verification); load references/two_layer_detection.md only when the verification method is ambiguous.

1. Parse context -- extract fields, determine scan_path (domain-aware if specified), extract output_dir
2. Scan codebase for violations (Layer 1)
   • All Grep/Glob patterns use scan_path (not codebase_root)
   • Graph acceleration (if available): IF contextStore.graph_indexed OR .hex-skills/codegraph/index.db exists:
     • Complexity + God classes: audit_workspace(path=scan_path, verbosity="minimal", limit=5) -- use returned hotspots to pre-identify complex functions and god classes. Raise limit only for deliberate drill-down.
     • Module metrics: analyze_architecture(path=scan_path, verbosity="full") -- use returned coupling metrics for cascade depth and coupling analysis.
     • Fall back to grep patterns below if graph unavailable.
     • Outline-first read: outline(file_path) before reading large source files -- understand function/class structure for complexity analysis.
   • Example: Grep(pattern="if.*if.*if", path=scan_path) for nesting detection
3. Analyze context per candidate (Layer 2 -- MANDATORY) Layer 1 finding without Layer 2 = NOT a valid finding. Before reporting, ask: "Is this violation intentional or justified by design?"
   • Cyclomatic complexity: is complexity from switch/case on enum (valid) or deeply nested conditions (bad)? Enum dispatch -> downgrade to LOW or skip
   • O(n^2): read context -- what's n? If bounded (n < 100), downgrade severity
   • God class: is it a config/schema/builder class? -> downgrade
   • Identifier drift: is the rename mediated by an explicit serializer alias (@JsonProperty, alias_generator, @SerializedName) or an ORM column mapping (@Column(name=...))? If yes -> downgrade or skip
4. Collect findings with severity, location, effort, recommendation
   • Tag each finding with domain: domain_name (if domain-aware)
5. Calculate score using penalty algorithm
6. Write Report: Build full markdown report in memory per references/templates/audit_worker_report_template.md, write to {output_dir}/ln-624--{domain}.md (or 624-quality.md in global mode) in single Write call
7. Return Summary: Return minimal summary (see Output Format)

Audit Rules (Priority: MEDIUM)

1. Cyclomatic Complexity

What: Too many decision points in single function (> 10)

Detection:

• Count if/else, switch/case, ternary, &&, ||, for, while
• Use tools: eslint-plugin-complexity, radon (Python), gocyclo (Go)

Severity:

• HIGH: Complexity > 20 (extremely hard to test)
• MEDIUM: Complexity 11-20 (refactor recommended)
• LOW: Complexity 8-10 (acceptable but monitor)
• Downgrade when: Enum/switch dispatch, state machines, parser grammars -> downgrade to LOW or skip

Recommendation: Split function, extract helper methods, use early returns

Effort: M-L (depends on complexity)

2. Deep Nesting (> 4 levels)

What: Nested if/for/while blocks too deep

Detection:

• Count indentation levels
• Pattern: if { if { if { if { if { ... } } } } }

Severity:

• HIGH: > 6 levels (unreadable)
• MEDIUM: 5-6 levels
• LOW: 4 levels
• Downgrade when: Nesting from early-return guard clauses (structurally deep but linear logic) -> downgrade

Recommendation: Extract functions, use guard clauses, invert conditions

Effort: M (refactor structure)

3. Long Methods (> 50 lines)

What: Functions too long, doing too much

Detection:

• Count lines between function start and end
• Exclude comments, blank lines

Severity:

• HIGH: > 100 lines
• MEDIUM: 51-100 lines
• LOW: 40-50 lines (borderline)
• Downgrade when: Orchestrator functions with sequential delegation; data transformation pipelines -> downgrade

Recommendation: Split into smaller functions, apply Single Responsibility

Effort: M (extract logic)

4. God Classes/Modules (> 500 lines)

What: Files with too many responsibilities

Detection:

• Count lines in file (exclude comments)
• Check number of public methods/functions

Severity:

• HIGH: > 1000 lines
• MEDIUM: 501-1000 lines
• LOW: 400-500 lines
• Downgrade when: Config/schema/migration files, generated code, barrel/index files -> skip

Recommendation: Split into multiple files, apply separation of concerns

Effort: L (major refactor)

5. Too Many Parameters (> 5)

What: Functions with excessive parameters

Detection:

• Count function parameters
• Check constructors, methods

Severity:

• MEDIUM: 6-8 parameters
• LOW: 5 parameters (borderline)
• Downgrade when: Builder/options pattern constructor; framework-required signatures (middleware, hooks) -> skip

Recommendation: Use parameter object, builder pattern, default parameters

Effort: S-M (refactor signature + calls)

6. O(n^2) or Worse Algorithms

What: Inefficient nested loops over collections

Detection:

• Nested for loops: for (i) { for (j) { ... } }
• Nested array methods: arr.map(x => arr.filter(...))

Severity:

• HIGH: O(n^2) in hot path (API request handler)
• MEDIUM: O(n^2) in occasional operations
• LOW: O(n^2) on small datasets (n < 100)
• Downgrade when: Bounded n (n < 100 guaranteed by domain); one-time init/migration code -> downgrade to LOW or skip

Recommendation: Use hash maps, optimize with single pass, use better data structures

Effort: M (algorithm redesign)

7. Constants Management

What: Magic numbers/strings, decentralized constants, duplicates

Detection:

Issue	Pattern	Example
Magic numbers	Hardcoded numbers in conditions/calculations	if (status === 2)
Magic strings	Hardcoded strings in comparisons	if (role === 'admin')
Decentralized	Constants scattered across files	MAX_SIZE = 100 in 5 files
Duplicates	Same value multiple times	STATUS_ACTIVE = 1 in 3 places
No central file	Missing constants.ts or config.py	No single source of truth

Severity:

• HIGH: Magic numbers in business logic (payment amounts, statuses)
• MEDIUM: Duplicate constants (same value defined 3+ times)
• MEDIUM: No central constants file
• LOW: Magic strings in logging/debugging
• Downgrade when: HTTP status codes (200, 404, 500) -> skip. Math constants (0, 1, -1) in algorithms -> skip. Test data -> skip

Recommendation:

• Create central constants file (constants.ts, config.py, constants.go)
• Extract magic numbers to named constants: const STATUS_ACTIVE = 1
• Consolidate duplicates, import from central file
• Use enums for related constants

Effort: M (extract constants, update imports, consolidate)

8. Method Signature Quality

What: Poor method contracts reducing readability and maintainability

Detection:

Issue	Pattern	Example
Boolean flag params	>=2 boolean params in signature	def process(data, is_async: bool, skip_validation: bool)
Too many optional params	>=3 optional params with defaults	def query(db, limit=10, offset=0, sort="id", order="asc")
Inconsistent verb naming	Different verbs for same operation type in one module	get_user() vs fetch_account() vs load_profile()
Unclear return type	-> dict, -> Any, -> tuple without TypedDict/NamedTuple	def get_stats() -> dict instead of -> StatsResponse

Severity:

• MEDIUM: Boolean flag params (use enum/strategy), unclear return types
• LOW: Too many optional params, inconsistent naming

Recommendation:

• Boolean flags: replace with enum, strategy pattern, or separate methods
• Optional params: group into config/options dataclass
• Naming: standardize verb conventions per module (get_ for sync, fetch_ for async, etc.)
• Return types: use TypedDict, NamedTuple, or dataclass instead of raw dict/tuple

Effort: S-M (refactor signatures + callers)

9. Identifier Consistency Across Layers

What: Same concept uses different identifiers across API contracts, DTOs, services, repositories, DB columns, or internal modules

Detection:

Issue	Pattern	Example
External contract drift	API/OpenAPI/external-schema field name differs from DTO/service/repo/DB column	user_id in OpenAPI but uid in DTO, userId in service, user column in DB
Synonym drift (internal)	Same entity referenced by competing names across modules	customer vs client vs account vs user for one concept
Unmediated casing/translation	snake/camel/kebab swap without an explicit serializer alias	created_at API field assigned to creationTime with no alias declared
Abbreviation drift	Full and abbreviated forms coexist for one concept	organization vs org vs orgId vs organizationId

Severity:

• HIGH: External-contract field renamed inside code without an explicit serializer alias -- silent breakage risk when the upstream contract changes
• MEDIUM: Synonym drift for one entity across 3+ modules (customer / client / account)
• MEDIUM: Casing translation without an explicit alias mapping
• LOW: Two-variant drift in one bounded module; abbreviation drift in internal-only code
• Downgrade when: ORM-mediated mapping with explicit column alias, framework-required transforms (e.g. GraphQL camelCase via codegen), generated DTOs from contract, language-keyword collision forcing rename -> downgrade or skip

Layer 2 requirement: Synonym drift detection relies on a curated project glossary or on reading usage context. Grep alone is insufficient -- always confirm the two identifiers refer to the same concept before reporting.

Recommendation:

• External-contract case: carry the external API name as-is through DTO / service / repository / DB column. If casing or language conventions conflict, configure a serializer alias once at the boundary (@JsonProperty, alias_generator, @SerializedName) rather than renaming the field inside the code
• Internal-only case: pick the most semantically precise variant, apply find/replace across the modules, record the canonical term in a shared glossary or shared constants/enum module. Add a lint rule or codegen step where possible to prevent reintroduction
• For verb naming within a single module, see Rule #8 (Method Signature Quality)

Effort: S-M (rename + serializer config). L when a DB column rename plus migration is required

Scoring Algorithm

MANDATORY READ: Load references/audit_scoring.md.

Output Format

MANDATORY READ: Load references/templates/audit_worker_report_template.md.

Write JSON summary per references/audit_summary_contract.md. In managed mode the caller passes both runId and summaryArtifactPath; in standalone mode the worker generates its own run-scoped artifact path per shared contract.

Write report to {output_dir}/ln-624--{domain}.md (or 624-quality.md in global mode) with category: "Code Maintainability Hotspots" and checks: cyclomatic_complexity, deep_nesting, long_methods, god_classes, too_many_params, quadratic_algorithms, magic_numbers, method_signatures, identifier_consistency.

When summaryArtifactPath is absent, write the standalone runtime summary under .hex-skills/runtime-artifacts/runs/{run_id}/evaluation-worker/{worker}--{identifier}.json and optionally echo the same summary in structured output.

Report written: .hex-skills/runtime-artifacts/runs/{run_id}/audit-report/ln-624--orders.md
Score: X.X/10 | Issues: N (C:N H:N M:N L:N)

Critical Rules

Apply the already-loaded references/audit_worker_core_contract.md.

• Do not auto-fix: Report only
• Domain-aware scanning: If domain_mode="domain-aware", scan ONLY scan_path (not entire codebase)
• Tag findings: Include domain field in each finding when domain-aware
• Metrics tools: Use existing tools when available (ESLint complexity plugin, radon, gocyclo)
• Unique angle: Audit local maintainability hotspots only. Do not audit duplication, package health, architecture boundaries, N+1 persistence behavior, or orchestration ownership. Identifier-consistency findings cover naming continuity of one concept across layers; this is distinct from ln-623 (code duplication) and ln-643 (DTO presence / layer leakage in signatures).
• Action required: Every finding uses REFACTOR_HOTSPOT, SIMPLIFY_SIGNATURE, EXTRACT_CONSTANT, or UNIFY_IDENTIFIER.

Definition of Done

Apply the already-loaded references/audit_worker_core_contract.md.

• contextStore parsed (including domain_mode, current_domain, output_dir)
• scan_path determined (domain path or codebase root)
• All 9 checks completed (scoped to scan_path):
  • complexity, nesting, length, god classes, parameters, O(n^2), constants, method signatures, identifier consistency
• Findings collected with severity, location, effort, recommendation, domain
• Score calculated
• Report written to {output_dir}/ln-624--{domain}.md (atomic single Write call)
• Summary written per contract

Reference Files

• Audit output schema: references/audit_output_schema.md

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Version: 3.0.0 Last Updated: 2025-12-23