Imported from IdoCohen560/claude-unity-game-studio (game-studios-template/.claude/skills/architecture-review/SKILL.md). Install upstream with npx skills add IdoCohen560/claude-unity-game-studio --skill architecture-review. Copyright stays with the author.

Architecture Review

The architecture review validates that the complete body of architectural decisions covers all game design requirements, is internally consistent, and correctly targets the project's pinned engine version. It is the quality gate between Technical Setup and Pre-Production.

Argument modes:

• No argument / full: Full review — all phases
• coverage: Traceability only — which GDD requirements have no ADR
• consistency: Cross-ADR conflict detection only
• engine: Engine compatibility audit only
• single-gdd [path]: Review architecture coverage for one specific GDD
• rtm: Requirements Traceability Matrix — extends the standard matrix to include story file paths and test file paths; outputs docs/architecture/requirements-traceability.md with the full GDD requirement → ADR → Story → Test chain. Use in Production phase when stories and tests exist.

Phase 1: Load Everything

Phase 1a — L0: Summary Scan (fast, low tokens)

Before reading any full document, use Grep to extract ## Summary sections from all GDDs and ADRs:

Grep pattern="## Summary" glob="design/gdd/*.md" output_mode="content" -A 4
Grep pattern="## Summary" glob="docs/architecture/adr-*.md" output_mode="content" -A 3

For single-gdd [path] mode: use the target GDD's summary to identify which ADRs reference the same system (Grep ADRs for the system name), then full-read only those ADRs. Skip full-reading unrelated GDDs entirely.

For engine mode: only full-read ADRs — GDDs are not needed for engine checks.

For coverage or full mode: proceed to full-read everything below.

Phase 1b — L1/L2: Full Document Load

Read all inputs appropriate to the mode:

Design Documents

• All in-scope GDDs in design/gdd/ — read every file completely
• design/gdd/systems-index.md — the authoritative list of systems

Architecture Documents

• All in-scope ADRs in docs/architecture/ — read every file completely
• docs/architecture/architecture.md if it exists

Engine Reference

• docs/engine-reference/[engine]/VERSION.md
• docs/engine-reference/[engine]/breaking-changes.md
• docs/engine-reference/[engine]/deprecated-apis.md
• All files in docs/engine-reference/[engine]/modules/

Project Standards

• .claude/docs/technical-preferences.md

Report a count: "Loaded [N] GDDs, [M] ADRs, engine: [name + version]."

Also read docs/consistency-failures.md if it exists. Extract entries with Domain matching the systems under review (Architecture, Engine, or any GDD domain being covered). Surface recurring patterns as a "Known conflict-prone areas" note at the top of the Phase 4 conflict detection output.

Phase 2: Extract Technical Requirements from Every GDD

Pre-load the TR Registry

Before extracting any requirements, read docs/architecture/tr-registry.yaml if it exists. Index existing entries by id and by normalized requirement text (lowercase, trimmed). This prevents ID renumbering across review runs.

For each requirement you extract, the matching rule is:

1. Exact/near match to an existing registry entry for the same system → reuse that entry's TR-ID unchanged. Update the requirement text in the registry only if the GDD wording changed (same intent, clearer phrasing) — add a revised: [date] field.
2. No match → assign a new ID: next available TR-[system]-NNN for that system, starting from the highest existing sequence + 1.
3. Ambiguous (partial match, intent unclear) → ask the user:

   "Does '[new requirement text]' refer to the same requirement as TR-[system]-NNN: [existing text]', or is it a new requirement?" User answers: "Same requirement" (reuse ID) or "New requirement" (new ID).

For any requirement with status: deprecated in the registry — skip it. It was removed from the GDD intentionally.

For each GDD, read it and extract all technical requirements — things the architecture must provide for the system to work. A technical requirement is any statement that implies a specific architectural decision.

Categories to extract:

For each GDD, produce a structured list:

GDD: [filename]
System: [system name]
Technical Requirements:
  TR-[GDD]-001: [requirement text] → Domain: [Physics/Rendering/etc]
  TR-[GDD]-002: [requirement text] → Domain: [...]

This becomes the requirements baseline — the complete set of what the architecture must cover.

Phase 3: Build the Traceability Matrix

For each technical requirement extracted in Phase 2, search the ADRs:

1. Read every ADR's "GDD Requirements Addressed" section
2. Check if it explicitly references the requirement or its GDD
3. Check if the ADR's decision text implicitly covers the requirement
4. Mark coverage status:

Build the full matrix:

## Traceability Matrix

| Requirement ID | GDD | System | Requirement | ADR Coverage | Status |
|---------------|-----|--------|-------------|--------------|--------|
| TR-combat-001 | combat.md | Combat | Hitbox detection < 1 frame | ADR-0003 | ✅ |
| TR-combat-002 | combat.md | Combat | Combo window timing | — | ❌ GAP |
| TR-inventory-001 | inventory.md | Inventory | Persistent item storage | ADR-0005 | ✅ |

Count the totals: X covered, Y partial, Z gaps.

Phase 3b: Story and Test Linkage (RTM mode only)

Skip this phase unless the argument is rtm or full with stories present.

This phase extends the Phase 3 matrix to include the story that implements each requirement and the test that verifies it — producing the full Requirements Traceability Matrix (RTM).

Step 3b-1 — Load stories

Glob production/epics/**/*.md (excluding EPIC.md index files). For each story file:

• Extract TR-ID from the story's Context section
• Extract story file path, title, Status
• Extract ## Test Evidence section — the stated test file path

Step 3b-2 — Load test files

Glob tests/unit/**/*_test.* and tests/integration/**/*_test.*. Build an index: system → [test file paths].

For each test file path from Step 3b-1, confirm via Glob whether the file actually exists. Note MISSING if the stated path does not exist.

Step 3b-3 — Build the extended RTM

For each TR-ID in the Phase 3 matrix, add:

• Story: the story file path(s) that reference this TR-ID (may be multiple)
• Test File: the test file path stated in the story's Test Evidence section
• Test Status: COVERED (test file exists) / MISSING (path stated but not found) / NONE (no test path stated, story type may be Visual/Feel/UI) / NO STORY (requirement has no story yet — pre-production gap)

Extended matrix format:

## Requirements Traceability Matrix (RTM)

| TR-ID | GDD | Requirement | ADR | Story | Test File | Test Status |
|-------|-----|-------------|-----|-------|-----------|-------------|
| TR-combat-001 | combat.md | Hitbox < 1 frame | ADR-0003 | story-001-hitbox.md | tests/unit/combat/hitbox_test.gd | COVERED |
| TR-combat-002 | combat.md | Combo window | — | story-002-combo.md | — | NONE (Visual/Feel) |
| TR-inventory-001 | inventory.md | Persistent storage | ADR-0005 | — | — | NO STORY |

RTM coverage summary:

• COVERED: [N] — requirements with ADR + story + passing test
• MISSING test: [N] — story exists but test file not found
• NO STORY: [N] — requirements with ADR but no story yet
• NO ADR: [N] — requirements without architectural coverage (from Phase 3 gaps)
• Full chain complete (COVERED): [N/total] ([%])

Phase 4: Cross-ADR Conflict Detection

Compare every ADR against every other ADR to detect contradictions. A conflict exists when:

• Data ownership conflict: Two ADRs claim exclusive ownership of the same data
• Integration contract conflict: ADR-A assumes System X has interface Y, but ADR-B defines System X with a different interface
• Performance budget conflict: ADR-A allocates N ms to physics, ADR-B allocates N ms to AI, together they exceed the total frame budget
• Dependency cycle: ADR-A says System X initialises before Y; ADR-B says Y initialises before X
• Architecture pattern conflict: ADR-A uses event-driven communication for a subsystem; ADR-B uses direct function calls to the same subsystem
• State management conflict: Two ADRs define authority over the same game state (e.g. both Combat ADR and Character ADR claim to own the health value)

For each conflict found:

## Conflict: [ADR-NNNN] vs [ADR-MMMM]
Type: [Data ownership / Integration / Performance / Dependency / Pattern / State]
ADR-NNNN claims: [...]
ADR-MMMM claims: [...]
Impact: [What breaks if both are implemented as written]
Resolution options:
  1. [Option A]
  2. [Option B]

ADR Dependency Ordering

After conflict detection, analyse the dependency graph across all ADRs:

1. Collect all Depends On fields from every ADR's "ADR Dependencies" section
2. Topological sort: Determine the correct implementation order — ADRs with no dependencies come first (Foundation), ADRs that depend on those come next, etc.
3. Flag unresolved dependencies: If ADR-A's "Depends On" field references an ADR that is still Proposed or does not exist, flag it:

   ⚠️  ADR-0005 depends on ADR-0002 — but ADR-0002 is still Proposed.
       ADR-0005 cannot be safely implemented until ADR-0002 is Accepted.
   

4. Cycle detection: If ADR-A depends on ADR-B and ADR-B depends on ADR-A (directly or transitively), flag it as a DEPENDENCY CYCLE:

   🔴 DEPENDENCY CYCLE: ADR-0003 → ADR-0006 → ADR-0003
      This cycle must be broken before either can be implemented.
   

5. Output recommended implementation order:

   ### Recommended ADR Implementation Order (topologically sorted)
   Foundation (no dependencies):
     1. ADR-0001: [title]
     2. ADR-0003: [title]
   Depends on Foundation:
     3. ADR-0002: [title] (requires ADR-0001)
     4. ADR-0005: [title] (requires ADR-0003)
   Feature layer:
     5. ADR-0004: [title] (requires ADR-0002, ADR-0005)
   

Phase 5: Engine Compatibility Cross-Check

Across all ADRs, check for engine consistency:

Version Consistency

• Do all ADRs that mention an engine version agree on the same version?
• If any ADR was written for an older engine version, flag it as potentially stale

Post-Cutoff API Consistency

• Collect all "Post-Cutoff APIs Used" fields from all ADRs
• For each, verify against the relevant module reference doc
• Check that no two ADRs make contradictory assumptions about the same post-cutoff API

Deprecated API Check

• Grep all ADRs for API names listed in deprecated-apis.md
• Flag any ADR referencing a deprecated API

Missing Engine Compatibility Sections

• List all ADRs that are missing the Engine Compatibility section entirely
• These are blind spots — their engine assumptions are unknown

Output format:

### Engine Audit Results
Engine: [name + version]
ADRs with Engine Compatibility section: X / Y total

Deprecated API References:
  - ADR-0002: uses [deprecated API] — deprecated since [version]

Stale Version References:
  - ADR-0001: written for [older version] — current project version is [version]

Post-Cutoff API Conflicts:
  - ADR-0004 and ADR-0007 both use [API] with incompatible assumptions

Engine Specialist Consultation

After completing the engine audit above, spawn the primary engine specialist via Task for a domain-expert second opinion:

• Read .claude/docs/technical-preferences.md Engine Specialists section to get the primary specialist
• If no engine is configured, skip this consultation
• Spawn subagent_type: [primary specialist] with: all ADRs that contain engine-specific decisions or Post-Cutoff APIs Used fields, the engine reference docs, and the Phase 5 audit findings. Ask them to:
  1. Confirm or challenge each audit finding — specialists may know of engine nuances not captured in the reference docs
  2. Identify engine-specific anti-patterns in the ADRs that the audit may have missed (e.g., using the wrong Godot node type, Unity component coupling, Unreal subsystem misuse)
  3. Flag ADRs that make assumptions about engine behaviour that differ from the actual pinned version

Incorporate additional findings under ### Engine Specialist Findings in the Phase 5 output. These feed into the final verdict — specialist-identified issues carry the same weight as audit-identified issues.

Phase 5b: Design Revision Flags (Architecture → GDD Feedback)

For each HIGH RISK engine finding from Phase 5, check whether any GDD makes an assumption that the verified engine reality contradicts.

Specific cases to check:

1. Post-cutoff API behaviour differs from training-data assumptions: If an ADR records a verified API behaviour that differs from the default LLM assumption, check all GDDs that reference the related system. Look for design rules written around the old (assumed) behaviour.

2. Known engine limitations in ADRs: If an ADR records a known engine limitation (e.g. "Jolt ignores HingeJoint3D damp", "D3D12 is now the default backend"), check GDDs that design mechanics around the affected feature.

3. Deprecated API conflicts: If Phase 5 flagged a deprecated API used in an ADR, check whether any GDD contains mechanics that assume the deprecated API's behaviour.

For each conflict found, record it in the GDD Revision Flags table:

### GDD Revision Flags (Architecture → Design Feedback)
These GDD assumptions conflict with verified engine behaviour or accepted ADRs.
The GDD should be revised before its system enters implementation.

| GDD | Assumption | Reality (from ADR/engine-reference) | Action |
|-----|-----------|--------------------------------------|--------|
| combat.md | "Use HingeJoint3D damp for weapon recoil" | Jolt ignores damp — ADR-0003 | Revise GDD |

If no revision flags are found, write: "No GDD revision flags — all GDD assumptions are consistent with verified engine behaviour."

Ask: "Should I flag these GDDs for revision in the systems index?"

• If yes: update the relevant systems' Status field to "Needs Revision" and add a short inline note in the adjacent Notes/Description column explaining the conflict. Ask for approval before writing. (Do NOT use parentheticals like "Needs Revision (Architecture Feedback)" — other skills match the exact string "Needs Revision" and parentheticals break that match.)

Phase 6: Architecture Document Coverage

If docs/architecture/architecture.md exists, validate it against GDDs:

• Does every system from systems-index.md appear in the architecture layers?
• Does the data flow section cover all cross-system communication defined in GDDs?
• Do the API boundaries support all integration requirements from GDDs?
• Are there systems in the architecture doc that have no corresponding GDD (orphaned architecture)?

Phase 7: Output the Review Report

## Architecture Review Report
Date: [date]
Engine: [name + version]
GDDs Reviewed: [N]
ADRs Reviewed: [M]

---

### Traceability Summary
Total requirements: [N]
✅ Covered: [X]
⚠️ Partial: [Y]
❌ Gaps: [Z]

### Coverage Gaps (no ADR exists)
For each gap:
  ❌ TR-[id]: [GDD] → [system] → [requirement]
     Suggested ADR: "/architecture-decision [suggested title]"
     Domain: [Physics/Rendering/etc]
     Engine Risk: [LOW/MEDIUM/HIGH]

### Cross-ADR Conflicts
[List all conflicts from Phase 4]

### ADR Dependency Order
[Topologically sorted implementation order from Phase 4 — dependency ordering section]
[Unresolved dependencies and cycles if any]

### GDD Revision Flags
[GDD assumptions that conflict with verified engine behaviour — from Phase 5b]
[Or: "None — all GDD assumptions consistent with verified engine behaviour"]

### Engine Compatibility Issues
[List all engine issues from Phase 5]

### Architecture Document Coverage
[List missing systems and orphaned architecture from Phase 6]

---

### Verdict: [PASS / CONCERNS / FAIL]

PASS: All requirements covered, no conflicts, engine consistent
CONCERNS: Some gaps or partial coverage, but no blocking conflicts
FAIL: Critical gaps (Foundation/Core layer requirements uncovered),
      or blocking cross-ADR conflicts detected

### Blocking Issues (must resolve before PASS)
[List items that must be resolved — FAIL verdict only]

### Required ADRs
[Prioritised list of ADRs to create, most foundational first]

Phase 8: Write and Update Traceability Index

Use AskUserQuestion for the write approval:

• "Review complete. What would you like to write?"
  • [A] Write all three files (review report + traceability index + TR registry)
  • [B] Write review report only — docs/architecture/architecture-review-[date].md
  • [C] Don't write anything yet — I need to review the findings first

RTM Output (rtm mode only)

For rtm mode, additionally ask: "May I write the full Requirements Traceability Matrix to docs/architecture/requirements-traceability.md?"

RTM file format:

# Requirements Traceability Matrix (RTM)

> Last Updated: [date]
> Mode: /architecture-review rtm
> Coverage: [N]% full chain complete (GDD → ADR → Story → Test)

## How to read this matrix

| Column | Meaning |
|--------|---------|
| TR-ID | Stable requirement ID from tr-registry.yaml |
| GDD | Source design document |
| ADR | Architectural decision governing implementation |
| Story | Story file that implements this requirement |
| Test File | Automated test file path |
| Test Status | COVERED / MISSING / NONE / NO STORY |

## Full Traceability Matrix

| TR-ID | GDD | Requirement | ADR | Story | Test File | Status |
|-------|-----|-------------|-----|-------|-----------|--------|
[Full matrix rows from Phase 3b]

## Coverage Summary

| Status | Count | % |
|--------|-------|---|
| COVERED — full chain complete | [N] | [%] |
| MISSING test — story exists, no test | [N] | [%] |
| NO STORY — ADR exists, not yet implemented | [N] | [%] |
| NO ADR — architectural gap | [N] | [%] |
| **Total requirements** | **[N]** | **100%** |

## Uncovered Requirements (Priority Fix List)

Requirements where the full chain is broken, prioritised by layer:

### Foundation layer gaps
[list with suggested action per gap]

### Core layer gaps
[list]

### Feature / Presentation layer gaps
[list — lower priority]

## History

| Date | Full Chain % | Notes |
|------|-------------|-------|
| [date] | [%] | Initial RTM |

TR Registry Update

Also ask: "May I update docs/architecture/tr-registry.yaml with new requirement IDs from this review?"

If yes:

• Append any new TR-IDs that weren't in the registry before this review
• Update requirement text and revised date for any entries whose GDD wording changed (ID stays the same)
• Mark status: deprecated for any registry entries whose GDD requirement no longer exists (confirm with user before marking deprecated)
• Never renumber or delete existing entries
• Update the last_updated and version fields at the top

This ensures all future story files can reference stable TR-IDs that persist across every subsequent architecture review.

Reflexion Log Update

After writing the review report, append any 🔴 CONFLICT entries found in Phase 4 to docs/consistency-failures.md (if the file exists):

### [YYYY-MM-DD] — /architecture-review — 🔴 CONFLICT
**Domain**: Architecture / [specific domain e.g. State Ownership, Performance]
**Documents involved**: [ADR-NNNN] vs [ADR-MMMM]
**What happened**: [specific conflict — what each ADR claims]
**Resolution**: [how it was or should be resolved]
**Pattern**: [generalised lesson for future ADR authors in this domain]

Only append CONFLICT entries — do not log GAP entries (missing ADRs are expected before the architecture is complete). Do not create the file if missing — only append when it already exists.

Session State Update

After writing all approved files, silently append to production/session-state/active.md:

## Session Extract — /architecture-review [date]
- Verdict: [PASS / CONCERNS / FAIL]
- Requirements: [N] total — [X] covered, [Y] partial, [Z] gaps
- New TR-IDs registered: [N, or "None"]
- GDD revision flags: [comma-separated GDD names, or "None"]
- Top ADR gaps: [top 3 gap titles from the report, or "None"]
- Report: docs/architecture/architecture-review-[date].md

If active.md does not exist, create it with this block as the initial content. Confirm in conversation: "Session state updated."

The traceability index format:

# Architecture Traceability Index
Last Updated: [date]
Engine: [name + version]

## Coverage Summary
- Total requirements: [N]
- Covered: [X] ([%])
- Partial: [Y]
- Gaps: [Z]

## Full Matrix
[Complete traceability matrix from Phase 3]

## Known Gaps
[All ❌ items with suggested ADRs]

## Superseded Requirements
[Requirements whose GDD was changed after the ADR was written]

Phase 9: Handoff

After completing the review and writing approved files, present:

1. Immediate actions: List the top 3 ADRs to create (highest-impact gaps first, Foundation layer before Feature layer)
2. Gate guidance: "When all blocking issues are resolved, run /gate-check pre-production to advance"
3. Rerun trigger: "Re-run /architecture-review after each new ADR is written to verify coverage improves"

Then close with AskUserQuestion:

• "Architecture review complete. What would you like to do next?"
  • [A] Write a missing ADR — open a fresh session and run /architecture-decision [system]
  • [B] Run /gate-check pre-production — if all blocking gaps are resolved
  • [C] Stop here for this session

Error Recovery Protocol

If any spawned agent returns BLOCKED, errors, or fails to complete:

1. Surface immediately: Report "[AgentName]: BLOCKED — [reason]" before continuing
2. Assess dependencies: If the blocked agent's output is required by a later phase, do not proceed past that phase without user input
3. Offer options via AskUserQuestion with three choices:
   • Skip this agent and note the gap in the final report
   • Retry with narrower scope (fewer GDDs, single-system focus)
   • Stop here and resolve the blocker first
4. Always produce a partial report — output whatever was completed so work is not lost

Collaborative Protocol

1. Read silently — do not narrate every file read
2. Show the matrix — present the full traceability matrix before asking for anything; let the user see the state
3. Don't guess — if a requirement is ambiguous, ask: "Is [X] a technical requirement or a design preference?"
4. Ask before writing — always confirm before writing the report file
5. Non-blocking — the verdict is advisory; the user decides whether to continue despite CONCERNS or even FAIL findings