Create Architecture

!bash "${CLAUDE_SKILL_DIR}/../../hooks/yaml-helper.sh" resolve_config --keys review_mode,automation,workflow,docs.density

Resolved above — use as-is; --review overrides review_mode. No block → defaults in .claude/docs/config-resolution.md.

Create Architecture

This skill produces docs/architecture/architecture.md — the master architecture document that translates all approved GDDs into a concrete technical blueprint. It sits between design and implementation, and must exist before sprint planning begins.

Distinct from /architecture-decision: ADRs record individual point decisions. This skill creates the whole-system blueprint that gives ADRs their context.

See .claude/docs/director-gates.md for the full check pattern. Individual gate definitions live in .claude/docs/director-gates/[gate-id].md — the spawned agent reads its own gate file; do not read it in the parent session.

Every AskUserQuestion call follows .claude/docs/automation-modes.md (collaborative asks always · guided major-only · autonomous logs and proceeds; automation_always_ask categories always prompt).

docs.density — it controls per-section depth, where workflow controls which sections exist. modes.rigor sets both together; set docs.density explicitly to vary depth alone: terse (the default, via rigor: minimal) = layer diagrams + decision bullets, no essays; balanced = diagrams + paragraph explanations of layer choices (rigor: standard); thorough = full prose with rationale, trade-offs, and alternatives considered per layer. Apply it to every section you author.

workflow (see .claude/docs/workflow-modes.md):

• full — full architecture: all layers, module ownership, data flow, API boundaries, full ADR audit.
• standard — simplified: system layer map + critical ADR list only.
• minimal — not required. Can still be run voluntarily.

Argument modes:

• No argument / full: Full guided walkthrough — all sections, start to finish
• layers: Focus on the system layer diagram only
• data-flow: Focus on data flow between modules only
• api-boundaries: Focus on API boundary definitions only
• adr-audit: Audit existing ADRs for engine compatibility gaps only

Phase 0: Load All Context

Before anything else, load the full project context in this order:

0a. Engine Context (Critical)

Read the four project-wide engine documents in full — they are small, and every part of each is used:

1. docs/engine-reference/[engine]/VERSION.md → Extract: engine name, version, LLM cutoff, post-cutoff risk levels
2. docs/engine-reference/[engine]/breaking-changes.md → Extract: all HIGH and MEDIUM risk changes
3. docs/engine-reference/[engine]/deprecated-apis.md → Extract: APIs to avoid
4. docs/engine-reference/[engine]/current-best-practices.md → Extract: post-cutoff best practices that differ from training data

Then read only the module docs whose domain this game actually uses — not the whole modules/ directory:

5. docs/engine-reference/[engine]/modules/ — glob it to establish what exists, then match against the domains present in design/gdd/systems-index.md (the same domain vocabulary the ADR template uses: Physics, Rendering, UI, Audio, Navigation, Animation, Networking, Core, Input). Read the matching modules; skip the rest. → Extract: current API patterns per domain

   A game with no multiplayer system does not need the networking module loaded to write its architecture, and loading it costs the same as one that does. If the domain match is ambiguous, read the module — a missed engine constraint is far more expensive here than a redundant read, because this phase is where those constraints get baked into the architecture.

If no engine is configured, stop and prompt:

"No engine is configured. Run /setup-engine first. Architecture cannot be written without knowing which engine and version you are targeting."

0b. Design Context + Technical Requirements Extraction

Load the approved design documents and extract technical requirements from each:

1. design/gdd/game-concept.md — game pillars, genre, core loop
2. design/gdd/systems-index.md — all systems, dependencies, priority tiers

Check both exist before reading either. Neither is optional here, and both need an absence branch — §0a stops for an unconfigured engine, and these two matter just as much:

• systems-index.md absent — stop:

  "No systems index found. Run /map-systems first. An architecture written without it invents layers for systems nobody mapped, and every ADR, epic and story downstream inherits that invention." At minimal the index is not required (§ tier note above) — say so and proceed from the brief instead.

• game-concept.md absent — at standard/full, stop and point at /brainstorm. At minimal, read design/game-brief.md in its place; if that is absent too, stop — there is no design record to architect against.
• Either present but empty or still template placeholders — treat as absent. Present-but-empty is the case that most looks like present.

Do not proceed on a partial read and note it later. This phase is where design assumptions get baked into ADRs, and an assumption made here is re-derived by everything downstream rather than re-checked. 3. Project config — naming.* and performance.* from project.yaml (for any key absent or empty, fall back to .claude/docs/technical-preferences.md); allowed libraries and forbidden patterns from .claude/docs/technical-preferences.md (not migrated to project.yaml) 4. Every GDD in design/gdd/ — extract technical requirements from the sections that carry them, not from whole files. Establish the denominator first (glob design/gdd/*.md, count N), then:

Grep pattern="^## (Detailed Rules|Detailed Design|Formulas|Dependencies|Tuning Knobs|Acceptance Criteria)" glob="design/gdd/*.md" output_mode="content" -A 40

Overview and Player Fantasy are narrative and imply no architecture; the scanned set is where rules, numbers, and cross-system contracts live. Accept either ## Detailed Rules or ## Detailed Design — the design standard and the GDD template disagree on the name and they denote the same section.

Full-read a GDD when it matched zero sections (it predates the template — a zero-match means "unstructured", never "no requirements") or when a scanned section refers to material outside itself. Never treat an absent section as an absent requirement: report any GDD that contributed nothing, rather than letting it drop silently out of the baseline below.

For each, extract:

• Data structures implied by the game rules
• Performance constraints stated or implied
• Engine capabilities the system requires
• Cross-system communication patterns (what talks to what, how)
• State that must persist (save/load implications)
• Threading or timing requirements

Build a Technical Requirements Baseline — a flat list of all extracted requirements across all GDDs, numbered TR-[gdd-slug]-[NNN]. This is the complete set of what the architecture must cover. Present it as:

## Technical Requirements Baseline
Extracted from [N] GDDs | [X] total requirements

| Req ID | GDD | System | Requirement | Domain |
|--------|-----|--------|-------------|--------|
| TR-combat-001 | combat.md | Combat | Hitbox detection per-frame | Physics |
| TR-combat-002 | combat.md | Combat | Combo state machine | Core |
| TR-inventory-001 | inventory.md | Inventory | Item persistence | Save/Load |

This baseline feeds into every subsequent phase. No GDD requirement should be left without an architectural decision to support it by the end of this session.

0c. Existing Architecture Decisions

To learn what has already been decided and in which domain, scan the ADR headers — do not full-read every ADR to produce a list of numbers and domains:

Grep pattern="^## (Status|Summary)" glob="docs/architecture/adr-*.md" output_mode="content" -A 4
Grep pattern="\*\*Domain\*\*" glob="docs/architecture/adr-*.md" output_mode="content"

## Summary (a 2-sentence what-and-why) plus ## Status and the Engine Compatibility Domain field are exactly "what was decided and its domain". List the ADRs found, their status, and their domains from the scan. Full-read a specific ADR only when a new decision this session would collide with it and you need its reasoning — not to build the inventory.

0d. Generate Knowledge Gap Inventory

Before proceeding, display a structured summary:

## Engine Knowledge Gap Inventory
Engine: [name + version]
LLM Training Covers: up to approximately [version]
Post-Cutoff Versions: [list]

### HIGH RISK Domains (must verify against engine reference before deciding)
- [Domain]: [Key changes]

### MEDIUM RISK Domains (verify key APIs)
- [Domain]: [Key changes]

### LOW RISK Domains (in training data, likely reliable)
- [Domain]: [no significant post-cutoff changes]

### Systems from GDD that touch HIGH/MEDIUM risk domains:
- [GDD system name] → [domain] → [risk level]

Use AskUserQuestion:

• Prompt: "One or more engine domains are HIGH RISK — the LLM's knowledge may be unreliable for these areas. Architectural recommendations in these domains should be cross-referenced with the engine docs before being acted on. How would you like to proceed?"
• Options:
  • [A] Proceed — flag HIGH RISK domains throughout the output
  • [B] Let me check the engine reference first — pause here
  • [C] Show me which domains are HIGH RISK and why

0e. Existing Architecture Document

Glob docs/architecture/architecture.md. If it exists, this run updates it — it never replaces it unasked. Read its ## Document Status block and its ## headings, then use AskUserQuestion:

• Prompt: "An architecture document already exists (v[N], [last updated]). What should this run do?"
• Options: [A] Update chosen sections in place / [B] Rewrite the whole document — replaces the existing file / [C] Stop

On [A], ask which sections. Phases 1–6 author only those and say which they skipped; Phase 7 replaces just those sections and raises Version to N+1, leaving every other section as it is. [B] runs the full walkthrough, and Phase 7's ask says it replaces the existing file.

A focus-area argument (layers, data-flow, api-boundaries, adr-audit) is [A] with that one section chosen: it runs only its phase (1, 3, 4 or 5), and Phase 7 writes that section. Phase 7b still runs on the updated document — an update is reviewed like a first draft, at the review modes that review one. With no existing document there is nothing to update — say so, and offer the full walkthrough instead.

Phase 1: System Layer Mapping

Map every system from systems-index.md into an architecture layer. The standard game architecture layers are:

┌─────────────────────────────────────────────┐
│  PRESENTATION LAYER                         │  ← UI, HUD, menus, VFX, audio
├─────────────────────────────────────────────┤
│  FEATURE LAYER                              │  ← gameplay systems, AI, quests
├─────────────────────────────────────────────┤
│  CORE LAYER                                 │  ← physics, input, combat, movement
├─────────────────────────────────────────────┤
│  FOUNDATION LAYER                           │  ← engine integration, save/load,
│                                             │    scene management, event bus
├─────────────────────────────────────────────┤
│  PLATFORM LAYER                             │  ← OS, hardware, engine API surface
└─────────────────────────────────────────────┘

For each GDD system, ask:

• Which layer does it belong to?
• What are its module boundaries?
• What does it own exclusively? (data, state, behaviour)

Present the proposed layer assignment and ask for approval before proceeding to the next section. Record the approved layer map in production/session-state/active.md; it goes into the document at Phase 7.

Engine awareness check: For each system assigned to the Core and Foundation layers, flag if it touches a HIGH or MEDIUM risk engine domain. Show the relevant engine reference excerpt inline.

Phase 2: Module Ownership Map

For each module defined in Phase 1, define ownership:

• Owns: what data and state this module is solely responsible for
• Exposes: what other modules may read or call
• Consumes: what it reads from other modules
• Engine APIs used: which specific engine classes/nodes/signals this module calls directly (with version and risk level noted)

Format as a table per layer, then as an ASCII dependency diagram.

Engine awareness check: For every engine API listed, verify against the relevant module reference doc. If an API is post-cutoff, flag it:

⚠️  [ClassName.method()] — Godot 4.6 (post-cutoff, HIGH risk)
    Verified against: docs/engine-reference/godot/modules/[domain].md
    Behaviour confirmed: [yes / NEEDS VERIFICATION]

Get user approval on the ownership map, then record it in production/session-state/active.md; it is written at Phase 7.

Phase 3: Data Flow

Define how data moves between modules during key game scenarios. Cover at minimum:

1. Frame update path: Input → Core systems → State → Rendering
2. Event/signal path: How systems communicate without tight coupling
3. Save/load path: What state is serialised, which module owns serialisation
4. Initialisation order: Which modules must boot before others

Use ASCII sequence diagrams where helpful. For each data flow:

• Name the data being transferred
• Identify the producer and consumer
• State whether this is synchronous call, signal/event, or shared state
• Flag any data flows that cross thread boundaries

Get user approval on each scenario, then record it in production/session-state/active.md; it is written at Phase 7.

Phase 4: API Boundaries

Define the public contracts between modules. For each boundary:

• What is the interface a module exposes to the rest of the system?
• What are the entry points (functions/signals/properties)?
• What invariants must callers respect?
• What must the module guarantee to callers?

Write in pseudocode or the project's actual language (from technical preferences). These become the contracts programmers implement against.

Engine awareness check: If any interface uses engine-specific types (e.g. Node, Resource, Signal in Godot), flag the version and verify the type exists and has not changed signature in the target engine version.

Get user approval on the API boundaries, then record them in production/session-state/active.md; they are written at Phase 7.

Phase 5: ADR Audit + Traceability Check

Review all existing ADRs from Phase 0c against both the architecture built in Phases 1-4 AND the Technical Requirements Baseline from Phase 0b.

ADR Quality Check

For each ADR:

• Does it have an Engine Compatibility section?
• Is the engine version recorded?
• Are post-cutoff APIs flagged?
• Does it have a "GDD Requirements Addressed" section?
• Does it conflict with the layer/ownership decisions made in this session?
• Is it still valid for the pinned engine version?