ln-645-architecture-modernization-auditor

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

Architecture Modernization Auditor

Type: L3 Worker

L3 Worker that finds architecture-level simplification and modernization opportunities.

Purpose & Scope

• Audit obsolete custom architectural mechanisms, overbuilt extension points, and avoidable architecture indirection
• Identify mechanisms that increase maintenance cost without current architectural value
• Generate migration-safe modernization findings
• Emit SIMPLIFY_ARCHITECTURE, RETIRE_CUSTOM_MECHANISM, or CONSOLIDATE_EXTENSION_POINT
• Calculate compliance score (X/10)

Inputs

MANDATORY READ: Load references/audit_worker_core_contract.md and references/mcp_tool_preferences.md. Tool policy: You may run as an isolated subagent where host AGENTS.md is not in scope, so default to hex-line MCP first for file reads, search, and edits. Load references/mcp_integration_patterns.md only when MCP behavior is unclear.

Receives contextStore with: tech_stack, architecture, codebase_root, output_dir, domain_mode, scan_path.

Use hex-graph first when references, architecture metrics, or implementation relationships materially improve modernization findings. Use hex-line first for local code reads when available. If MCP is unavailable, unsupported, or not indexed, continue with built-in Read/Grep/Glob/Bash and state the fallback in the report.

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 -- determine scan_root from domain-aware scope or codebase root
2. Find modernization candidates (Layer 1)
   • Custom plugin/extension systems with one implementation
   • Hand-built service locators, registries, dispatchers, buses, adapters, or factories with limited use
   • Legacy architecture mechanisms with deprecation comments or unused compatibility branches
   • Parallel architectural mechanisms solving the same problem
3. Verify architectural value (Layer 2)
   • Is the mechanism required by the framework or deployment model? -> skip
   • Is it a public extension API with external consumers? -> downgrade or skip
   • Does it isolate a volatile boundary with multiple real implementations? -> skip
   • Is the replacement only a package swap or utility rewrite? -> skip
4. Collect findings with severity, location, action, effort, migration risk, and recommendation
5. Calculate score using references/audit_scoring.md
6. Write report to {output_dir}/ln-645--{identifier}.md
7. Return summary per references/audit_summary_contract.md

Audit Rules

1. Obsolete Custom Mechanisms

What: Custom architecture mechanisms kept after the project no longer needs them

Detection:

• Search for Legacy, Compat, Shim, Adapter, Registry, Plugin, Extension, ServiceLocator, Dispatcher, EventBus
• Check references and implementation count
• Read deprecation/TODO comments and ADRs when present

Severity: HIGH for critical-path mechanisms, MEDIUM for broad but non-critical mechanisms, LOW for isolated cleanup

Action: RETIRE_CUSTOM_MECHANISM

2. Overbuilt Extension Points

What: Extension or plugin architecture with one implementation and no active variation point

Detection:

• Interfaces/abstract classes used only by one implementation
• Factories or registries with one registered type
• Configuration-driven plugin loading with one hardcoded plugin

Severity: MEDIUM by default, HIGH when the indirection hides critical flow

Action: CONSOLIDATE_EXTENSION_POINT

3. Parallel Architectural Mechanisms

What: Two or more architecture mechanisms solve the same problem in different modules

Detection:

• Multiple dispatch/registry/event mechanisms
• Multiple service composition styles
• Multiple adapter conventions for the same boundary

Severity: HIGH when it creates inconsistent behavior, MEDIUM when it mainly increases maintenance cost

Action: SIMPLIFY_ARCHITECTURE

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-645--{identifier}.md with category: "Architecture Modernization" and checks: obsolete_mechanisms, overbuilt_extension_points, parallel_mechanisms.

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.

Critical Rules

Apply the already-loaded references/audit_worker_core_contract.md.

• Do not auto-fix: Report only, never rewrite architecture
• Unique angle: Audit architecture-level modernization only. Do not audit package health, CVEs, generic utility replacement, code complexity, or runtime configuration hygiene.
• No package recommendations: Do not search for OSS replacements or recommend dependency swaps.
• Evidence required: Every modernization finding must include implementation count, reference evidence, and migration risk.
• Action required: Every finding uses SIMPLIFY_ARCHITECTURE, RETIRE_CUSTOM_MECHANISM, or CONSOLIDATE_EXTENSION_POINT.

Definition of Done

Apply the already-loaded references/audit_worker_core_contract.md.

• contextStore parsed successfully
• scan_root determined
• obsolete custom mechanisms checked
• overbuilt extension points checked
• parallel architectural mechanisms checked
• Layer 2 architectural value verification applied
• Findings collected with severity, location, action, effort, migration risk, and recommendation
• Score calculated per references/audit_scoring.md
• Report written to {output_dir}/ln-645--{identifier}.md (atomic single Write call)
• Summary written per contract

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Version: 1.0.0 Last Updated: 2026-02-26