Architectural Audit Skill

Audit the codebase for adherence to architectural standards and rules.

When to Use

• User says "audit arch", "audit architecture", "check architecture"

Critical Constraints

NEVER:

• Modify any source code files
• Update an existing report - always generate new

ALWAYS:

• Use subagents for parallel exploration
• Write report to temp/audit-arch/arch_audit_{YYYY-MM-DD_HHMMSS}.md (relative to the current working directory)
• Provide file paths and line numbers
• Categorize by severity (CRITICAL, HIGH, MEDIUM, LOW)

Architectural Principles

Principle 1: Single Source of Truth

Rule: All state reads must come from the authoritative source (database, API, configuration management). File outputs and caches are write-only. Systems never read files back as the primary source of state.

Audit Strategy - Data Flow Tracing:

1. Find all file read operations in core application code

2. For each read, trace the data flow:

   • What data is being read?
   • Does it influence system behavior or state?

3. Identify the PRIMARY source:

   • If file is read first and authoritative source synced afterward, file is PRIMARY (CRITICAL violation)
   • If authoritative source is read first, authoritative source is PRIMARY (compliant)

4. Check write/read symmetry:

   • Find artifact writes, check for corresponding reads
   • If system reads back what it wrote, that's a violation

Key Questions:

• "If this file didn't exist, would the system fail or query the authoritative source?"
• "Does the order of operations show file-first or authoritative-source-first?"

Critical: Apply this to ALL state loading code paths. Any component that restores or reconstructs system state must be examined. File-first with authoritative source sync afterward is still file-primary.

Cross-Reference: If you discover file-first patterns while auditing other principles, report them here as P1 violations, not just as inconsistencies.

Principle 2: Domain-Based Organization

Rule: Clear separation between domains with consistent structure.

Common patterns:

• Core domain logic separated from infrastructure
• Clear boundaries between business logic, data access, presentation
• Shared utilities in well-defined locations
• No mixing of concerns (e.g., CLI logic in database layer)

Audit Strategy:

• Check for misplaced components (utilities at root, API code in data layer)
• Find orphaned/empty directories from incomplete migrations
• Identify duplicates across locations
• Verify domain boundaries are respected

Principle 3: Dependency Layering

Rule: Dependencies flow one direction. Higher layers depend on lower layers, never reverse.

Typical layering:

presentation/  -> depends on business logic, data access
business logic -> depends on data access, infrastructure
data access    -> depends on infrastructure only
infrastructure -> depends on nothing project-specific

Also check internal layering: Within a domain, core modules should not import from higher-level modules (handlers, controllers, UI).

Audit Strategy:

• Scan imports in each layer for boundary violations
• Look for deferred imports (indicate architectural debt)
• Check that foundational layers don't depend on higher layers
• Verify circular dependencies don't exist

Principle 4: No Cross-Domain Imports

Rule: Separate domains/modules must be independent. Feature A cannot import from Feature B directly.

Audit Strategy:

• Scan each domain for imports from other domains at the same layer
• Shared functionality should be in common utilities or lower layers
• Check for tight coupling between features

Principle 5: Architecture Pattern Consistency

Rule: When using architectural patterns (MVC, repository pattern, state machines, etc.), implementations must follow consistent patterns across the codebase.

Audit Strategy:

• Identify the architectural patterns in use
• Compare implementations across different modules
• Check if patterns diverge - is it intentional or inconsistency?
• Look for pattern violations (e.g., bypassing the repository layer)

Important: If a component bypasses the established pattern to use file-first state loading, that's a P1 violation - report it under P1, not here.

Principle 6: No Code Duplication

Rule: Shared functionality exists in exactly one location.

Audit Strategy:

• Find functions/classes with same name in multiple locations
• Check migration pairs: old location should only re-export, not duplicate
• Look for copy-pasted code blocks with slight variations
• Identify logic that could be extracted to shared utilities

Migration Awareness: During migration, shims are acceptable only if they re-export from new location. Full duplicate implementations are violations.

Principle 7: Data Access Pattern Compliance

Rule: All data access through designated abstraction layer (repositories, DAOs, services), never direct client usage in business logic.

Audit Strategy:

• Find direct database/API client usage outside designated data access layer
• Check for direct imports of database drivers, HTTP clients in business logic
• Verify all queries go through the abstraction layer

Principle 8: No Monolithic Files

Rule: No file should exceed 1000 lines. Large files should be decomposed.

Audit Strategy:

• Find files exceeding 1000 lines (exclude generated/vendored)
• Flag files approaching threshold (800+ lines) as warnings

Principle 9: Model Construction Integrity

Rule: When constructing models/objects from dicts/external data, use factory methods or full validation. Never manually select fields in constructor calls.

Rationale: Manual field selection silently drops unlisted fields. Optional fields are especially vulnerable since missing them causes no validation error.

Audit Strategy:

• Find Model(field1=dict["x"], field2=dict.get("y")) patterns
• Check if all source dict fields are mapped to target model
• Verify factory methods exist for cross-schema transformations
• Look for validation being skipped

Severity: HIGH - silent data loss breaks downstream consumers

Principle 10: External Interface Compliance

Rule: Classes extending external framework base classes must implement ALL interface methods explicitly. Avoid mixin patterns where method resolution order affects behavior.

Audit Strategy:

• Find classes extending external bases (framework classes, third-party libraries)
• Check mixin ordering: mixins should come BEFORE the base class they augment
• Verify both sync AND async methods work (not inherited NotImplementedError stubs)
• Confirm contract tests exist for external interface compliance

Severity: CRITICAL - Interface mismatches only surface at runtime in specific code paths

Principle 11: Dependency Currency

Rule: Direct dependencies should track current major versions. Minor/patch drift is acceptable; lagging a major version is not.

Audit Strategy:

• Compare installed major versions against current stable releases for key dependencies
• Flag any dependency more than one major version behind

Severity: MEDIUM - stale major versions accumulate migration debt and miss security fixes

Cross-Cutting Design Guidelines

These apply across all principles when evaluating architectural decisions:

1. Implicit correction masks upstream failures — Reject invalid input rather than fixing it. Examples: silent type conversion, default values for required fields, translation layers that never reject, retry loops that swallow errors.

2. Functions that accept all inputs without rejection are fallbacks, not validators — If a "validator" or "normalizer" never raises an error, it's hiding problems.

3. System-derived values belong in code, not external input — Values determined by workflow state (status, IDs, counts) should be set by the system that owns them, not expected from external sources.

4. No backward compatibility — Flag any code containing these keywords as violations: legacy, deprecated, backward, compat, migration shim, old format, previous version, for compatibility. Dead code should be deleted, not preserved with comments explaining why it exists.

Audit Workflow

1. Launch parallel subagents for each principle
2. Consolidate findings by principle and severity
3. Cross-reference: Ensure findings are categorized by the principle they violate, not just where discovered
4. Suggest new principle (optional) - see below
5. Write report to temp/audit-arch/arch_audit_{YYYY-MM-DD_HHMMSS}.md (relative to the current working directory)
6. Output summary to terminal

Principle Suggestion (Optional)

After consolidating findings, consider whether a new architectural principle would significantly benefit the codebase.

Criteria - ALL must be true:

• Not a one-off issue
• No existing principle covers it
• Would prevent recurring architectural debt or bugs
• Impact would be HIGH or CRITICAL level

If criteria met: Add "Suggested Principle" section to report with:

• One-sentence rule statement
• 2-3 specific locations that motivated it

If criteria NOT met: Omit section entirely. Do not suggest principles just to have a suggestion.

Exclusions

Do NOT flag:

• Test files
• Re-export shims (thin wrappers only)
• Project config reads (package.json, build configs)
• External tool output (test runner output, build logs)

Severity Guidelines

CRITICAL:

• Reading state from secondary sources instead of authoritative source
• Circular dependencies between domains
• External interface contract violations

HIGH:

• Lower layers importing from higher layers
• Cross-domain imports at same layer
• Duplicate implementations
• Manual field selection causing silent data loss

MEDIUM:

• Code in wrong domain
• Inconsistent patterns
• Deferred imports indicating debt
• Stale major version dependencies

LOW:

• Naming inconsistencies
• Empty directories not cleaned up