design-system

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

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

When this skill is invoked:

1. Parse Arguments & Validate

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 = bullet points, 2–5 lines per section, skip rationale and preambles; balanced = paragraphs with light rationale (default); thorough = full prose with rationale, examples, and alternatives considered. Apply it to every section you author. Mandated structures (the Formulas variable table, Given-When-Then acceptance criteria) are correctness requirements at every density — terse trims the surrounding prose, never the required structure itself.

A system name or retrofit path is required. If missing:

1. Check if design/gdd/systems-index.md exists.
2. If it exists: read it, find the highest-priority system with status "Not Started" or equivalent, and use AskUserQuestion:
   • Prompt: "The next system in your design order is [system-name] ([priority] | [layer]). Start designing it?"
   • Options: [A] Yes — design [system-name] / [B] Pick a different system / [C] Stop here
   • If [A]: proceed with that system name. If [B]: ask which system to design (plain text). If [C]: exit.
3. If no systems index exists, fail with:

   "Usage: /design-system <system-name> — e.g., /design-system movement Or to fill gaps in an existing GDD: /design-system retrofit design/gdd/[system-name].md No systems index found. Run /map-systems first to map your systems and get the design order."

Detect retrofit mode: If the argument starts with retrofit or the argument is a file path to an existing .md file in design/gdd/, enter retrofit mode:

1. Read the existing GDD file.
2. Identify which of the 8 possible sections are present (scan for section headings): Overview, Player Fantasy, Detailed Design/Rules, Formulas, Edge Cases, Dependencies, Tuning Knobs, Acceptance Criteria. Which of them are required depends on the effective tier (§1) — at standard only 5 are, plus Formulas for math categories, and Player Fantasy and Tuning Knobs are skipped by design. Report an absent section as a gap only when the tier requires it; otherwise list it as available-to-add. Calling all 8 required here reports two by-design-absent sections as gaps on every standard project.
3. Identify which sections contain only placeholder text ([To be designed] or equivalent — blank, a single line, or obviously incomplete).
4. Present to the user before doing anything:

   ## Retrofit: [System Name]
   File: design/gdd/[filename].md
   
   Sections already written (will not be touched):
   ✓ [section name]
   ✓ [section name]
   
   Missing or incomplete sections (will be authored):
   ✗ [section name] — missing
   ✗ [section name] — placeholder only
   

5. Ask: "Shall I fill the [N] missing sections? I will not modify any existing content."
6. If yes: proceed to Phase 2 (Gather Context) as normal, but in Phase 3 skip creating the skeleton (file already exists) and in Phase 4 skip sections that are already complete. Only run the section cycle for missing/ incomplete sections.
7. Never overwrite existing section content. Use Edit tool to replace only [To be designed] placeholders or empty section bodies.

If NOT in retrofit mode, normalize the system name to kebab-case for the filename (e.g., "combat system" becomes combat-system).

workflow for this system (per .claude/docs/workflow-modes.md) — use the system_overrides row for this system if the block lists one, else the project value.

The resolved tier determines which GDD sections are required (applied in §4). ## Summary is required at every tier and is not one of the 8 — §5-pre authors it unconditionally ("This runs at every tier"), but it appeared in none of the per-tier lists below, and these lists are what other skills and gates apply. A GDD checked against a tier list alone would pass with no Summary, the one section /review-all-gdds and the tiered-loading readers depend on. Read every list below as "## Summary, plus:".

• full — all 8 sections

• standard — Overview, Detailed Design, Edge Cases, Dependencies, Acceptance Criteria (5 required); Formulas conditional — required when the system defines numeric rules: rates, curves, thresholds, costs, damage, drop weights, or any value a balance pass would tune. Optional only when the system defines no such value. The Category in systems-index.md is a hint, not the test — Gameplay, Economy and Progression systems almost always qualify, and a Core, UI or Persistence system that defines a numeric rule qualifies too. If the Detailed Design states a quantity that is not a constant of the engine, Formulas is required. Player Fantasy and Tuning Knobs skipped unless workflow_overrides force them (tuning_knobs: true forces Tuning Knobs)

  Do not gate this on a category token. A rule of the form "required when the system category is combat / economy / progression / AI" does not work: those four tokens are not what /map-systems writes — templates/systems-index.md defines the categories as Core · Gameplay · Progression · Economy · Persistence · UI · Audio · Narrative · Meta and lists combat and AI as example systems under Gameplay. A combat system categorised exactly as the template instructs matches none of the four, and Formulas would be dropped for the system most likely to need it.

• minimal — a GDD is not required (the game brief replaces it). If invoked voluntarily at minimal, author exactly the 5 standard sections (Overview, Detailed Design, Edge Cases, Dependencies, Acceptance Criteria) — the conditional Formulas rule does NOT re-apply at minimal — and tell the user the GDD is optional at this workflow level.

Retrofit mode is unaffected — it fills whatever sections are missing regardless of tier.

2. Gather Context (Read Phase)

Read all relevant context before asking the user anything. This is the skill's primary advantage over ad-hoc design — it arrives informed.

2a: Required Reads

At minimal (design-system is voluntary at this tier): read design/game-brief.md in place of the game concept, and skip the systems-index read — neither game-concept.md nor systems-index.md exists at minimal. Author from the brief's relevant MVP feature and its core loop.

This callout keys on the PROJECT tier, not this system's effective tier. The two differ whenever workflow_overrides.system_overrides bumps one system above a minimal project — the configuration .claude/docs/settings-guidance.md advertises as the reason the override exists ("bump one deep system"). Those two files are absent because the project is minimal; raising this system to standard or full does not create them. So on a minimal project, take this branch even for an overridden system, and read the brief.

The effective tier still governs everything downstream — the required section set (§1), the skeleton (§3), the section cycle (§4) and §5a. Only the required-reads branch here follows the project tier.

Then derive Category, Layer and Priority from the brief, once, here. Six later steps are keyed on the systems index you just skipped — §2e's engine domain, Section A's and Section B's recommended options, the Visual/Audio REQUIRED table, §6 specialist routing, and §5-pre's Quick reference — and none of them has an absent-index branch. An overridden system reaches all six at standard or full, so "skip the index" leaves them with no input at all. Derive from the brief instead:

• Category — one of the nine in templates/systems-index.md (Core · Gameplay · Progression · Economy · Persistence · UI · Audio · Narrative · Meta), chosen from what the brief says the system does.
• Layer — Foundation if other systems depend on it, else Feature.
• Priority — MVP if the brief's build order lists it, else Post-MVP.

Carry all three for the rest of the run and treat them as the index's answer. Mark them inferred in §5-pre's Quick reference ("Category: Gameplay (inferred from the brief — no systems index at this tier)") so a later reader does not mistake a derivation for an indexed fact. Do not write a systems index to hold them: /map-systems owns that file (§5d).

Read literally without this rule, an overridden system resolves to full, falls through to the fail-fast reads below, and aborts with "No game concept found. Run /brainstorm first" — killing the escape hatch on step one of the very configuration it was built for.

• Game concept: Read design/gdd/game-concept.md — fail if missing:

  "No game concept found. Run /brainstorm first."

• Systems index: Read design/gdd/systems-index.md — fail if missing:

  "No systems index found. Run /map-systems first to map your systems."

• Target system: Find the system in the index. If not listed, warn:

  "[system-name] is not in the systems index. Would you like to add it, or design it as an off-index system?"

• Entity registry: Read design/registry/entities.yaml if it exists. Extract all entries referenced by or relevant to this system (grep referenced_by.*[system-name] and source.*[system-name]). Hold these in context as known facts — values that other GDDs have already established and this GDD must not contradict.
• Reflexion log: Read docs/consistency-failures.md if it exists. Extract entries whose Domain matches this system's category. These are recurring conflict patterns — present them under "Past failure patterns" in the Phase 2d context summary so the user knows where mistakes have occurred before in this domain.

2b: Dependency Reads

From the systems index, identify:

• Upstream dependencies: Systems this one depends on (decisions this system must respect).
• Downstream dependents: Systems that depend on this one (expectations this system must satisfy).

For each dependency GDD that exists, read only the four sections that carry the cross-system contract — not the whole GDD:

Grep pattern="## (Dependencies|Formulas|Edge Cases|Tuning Knobs)" glob="design/gdd/[dep].md" output_mode="content" -A 20

• Key interfaces and data flow (from Dependencies)
• Formulas that reference this system's outputs
• Edge cases that assume this system's behavior
• Tuning knobs that feed into this system

Much of this is already in entities.yaml (loaded in 2a) — the registry's formula_map/constant_map carry the owned values with their source:. Use the registry first; the section grep fills what it does not hold.

2c: Optional Reads

• Game pillars: Read design/gdd/game-pillars.md if it exists
• Existing GDD: Read design/gdd/[system-name].md if it exists (resume, don't restart from scratch)
• Related systems: do not glob-and-read design/gdd/*.md hunting for "thematically related" systems — there is no deterministic proxy for that and it is the read the registry exists to replace. entities.yaml (2a) already holds the cross-system facts a related GDD would supply. If a specific overlap is known, treat it as a dependency above and section-grep it; otherwise rely on the registry.

2d: Present Context Summary

Before starting design work, present a brief summary to the user:

Designing: [System Name]

• Priority: [from index] | Layer: [from index]
• Depends on: [list, noting which have GDDs vs. undesigned]
• Depended on by: [list, noting which have GDDs vs. undesigned]
• Existing decisions to respect: [key constraints from dependency GDDs]
• Pillar alignment: [which pillar(s) this system primarily serves]
• Known cross-system facts (from registry):
  • [entity_name]: [attribute]=[value], [attribute]=[value] (owned by [source GDD])
  • [item_name]: [attribute]=[value], [attribute]=[value] (owned by [source GDD])
  • [formula_name]: variables=[list], output=[min–max] (owned by [source GDD])
  • [constant_name]: [value] [unit] (owned by [source GDD]) (These values are locked — if this GDD needs different values, surface the conflict before writing. Do not silently use different numbers.)

If no registry entries are relevant: omit the "Known cross-system facts" section.

If any upstream dependencies are undesigned, warn:

"[dependency] doesn't have a GDD yet. We'll need to make assumptions about its interface. Consider designing it first, or we can define the expected contract and flag it as provisional."

2e: Technical Feasibility Pre-Check

Before asking the user to begin designing, load engine context and surface any constraints or knowledge gaps that will shape the design.

Step 1 — Determine the engine domain for this system: Map the system's category (from systems-index.md) to an engine domain:

Keyed on the Category column of systems-index.md. All nine categories templates/systems-index.md defines appear here; where a category spans several engine domains, pick the row matching what the system actually does and say which you picked.

Animation, Rendering and Networking are engine domains with no category of their own: a system needing them will be Gameplay or Core. Name the domain you read the reference for, whichever row you came in on.

Step 2 — Read engine context (if available):

• Identify the engine and version: read engine.name and engine.version from project.yaml. Resolve each field independently — if its key is absent or empty (including when project.yaml has no engine: block), fall back to .claude/docs/technical-preferences.md (a [TO BE CONFIGURED] value means not set)

• If engine is configured, read docs/engine-reference/[engine]/VERSION.md

• Read docs/engine-reference/[engine]/modules/[domain].md if it exists. If it does not exist, say so by name — "no engine reference for [domain] under docs/engine-reference/[engine]/modules/; feasibility not checked against the pinned engine" — and carry that into §5-pre. A silent skip here is indistinguishable from a feasibility check that ran and found nothing wrong, which is the failure .claude/rules/skill-authoring.md obligation 3 exists to stop.

  This is not a rare branch. The domain table above names Scripting and Core for five of the nine categories (Narrative, Progression, Economy → Scripting; Persistence, Meta → Core), plus a sub-row each under Gameplay and Core. The Godot reference ships animation, audio, input, navigation, networking, physics, rendering, ui — there is no scripting.md and no core.md. So the majority of non-Gameplay systems hit the absent branch every time, and if it exists turned that into silence. Either the reference gains those two files or the check reports it; until the former, do the latter.

• Read docs/engine-reference/[engine]/breaking-changes.md for domain-relevant entries

• Find the domain-matching ADRs without reading every ADR to learn the field you filter on — grep the Domain field first, then read only the matches:

  Grep pattern="\*\*Domain\*\*" glob="docs/architecture/adr-*.md" output_mode="content"
  

  Read only the ADRs whose Domain matches this system's category (its ## Decision and ## Engine Compatibility sections); skip the rest.

Step 3 — Present the Feasibility Brief:

If engine reference docs exist, present before starting design:

## Technical Feasibility Brief: [System Name]
Engine: [name + version]
Domain: [domain]

### Known Engine Capabilities (verified for [version])
- [capability relevant to this system]
- [capability 2]

### Engine Constraints That Will Shape This Design
- [constraint from engine-reference or existing ADR]

### Knowledge Gaps (verify before committing to these)
- [post-cutoff feature this design might rely on — mark HIGH/MEDIUM risk]

### Existing ADRs That Constrain This System
- ADR-XXXX: [decision summary] — means [implication for this GDD]
  (or "None yet")

If no engine reference docs exist (engine not yet configured), show a short note:

"No engine configured yet — skipping technical feasibility check. Run /setup-engine before moving to architecture if you haven't already."

Step 4 — Ask before proceeding:

Use AskUserQuestion:

• "Any constraints to add before we begin, or shall we proceed with these noted?"
  • Options: "Proceed with these noted", "Add a constraint first", "I need to check the engine docs — pause here"

Use AskUserQuestion:

• "Ready to start designing [system-name]?"
  • Options: "Yes, let's go", "Show me more context first", "Design a dependency first"

3. Create File Skeleton

Once the user confirms, immediately create the GDD file with empty section headers. This ensures incremental writes have a target.

Scaffold only the sections required at the resolved tier (§1): at standard, omit Player Fantasy and Tuning Knobs (and Formulas only when the system defines no numeric rule — see §1; the category is a hint, not the test); at full, scaffold all 8. Only the sections §1 named as omitted are skipped — do not leave empty [To be designed] placeholders for those. Every other section in the template is scaffolded with its placeholder, including the ones §4 has not decided yet. This sentence governs the three tier omissions above (Player Fantasy, Tuning Knobs, and Formulas when no numeric rule exists) and nothing else: it is not a licence to strip a section because it looks optional, and §4 cannot fill a section §3 never created.

Use the template structure from .claude/docs/templates/game-design-document.md:

# [System Name]

> **Status**: In Design
> **Author**: [user + agents]
> **Last Updated**: [today's date]
> **Last Verified**: [today's date]
> **Implements Pillar**: [from context]

## Summary

[To be designed]

> **Quick reference** — Layer: `[Foundation | Core | Feature | Presentation]` · Priority: `[MVP | Vertical Slice | Alpha | Full Vision]` · Key deps: `[System names or "None"]`

## Overview

[To be designed]

## Player Fantasy

[To be designed]

## Detailed Design

### Core Rules

[To be designed]

### States and Transitions

[To be designed]

### Interactions with Other Systems

[To be designed]

## Formulas

[To be designed]

## Edge Cases

[To be designed]

## Dependencies

[To be designed]

## Tuning Knobs

[To be designed]

## Visual/Audio Requirements

[To be designed]

## Game Feel

[To be designed]

## UI Requirements

[To be designed]

## Cross-References

[To be designed]

## Acceptance Criteria

[To be designed]

## Open Questions

[To be designed]

This skeleton and the template must stay identical in section set and order. They diverged once and it was invisible: the skeleton omitted ## Game Feel and ## Cross-References, so §3's own rule — "§4 cannot fill a section §3 never created" — made both unreachable at every tier, full included, while §3's prose above still said "every other section in the template is scaffolded". Two agents authoring a combat GDD noticed the gap only by opening the template. If you add a section to one file, add it to the other in the same commit.

Ask: "May I create the skeleton file at design/gdd/[system-name].md?"

If the user declines: Stop with the following message:

"Verdict: BLOCKED — skeleton creation declined. The design session cannot proceed without the skeleton file, as all subsequent phases use it as the base. Re-run /design-system [system] when ready to create the file." Do not proceed to Section A.

After writing, update production/session-state/active.md:

• Use Glob to check if the file exists.
• If it does not exist: use the Write tool to create it. Never attempt Edit on a file that may not exist.
• If it already exists: use the Edit tool to update the relevant fields.

File content:

• Task: Designing [system-name] GDD
• Current section: Starting (skeleton created)
• File: design/gdd/[system-name].md

4. Section-by-Section Design

Author only the sections required at the resolved tier (§1). At standard, the walk covers A (Overview), C (Detailed Design), E (Edge Cases), F (Dependencies), H (Acceptance Criteria) — plus D (Formulas) when the system defines numeric rules (see §1; the category is a hint, not the test); skip B (Player Fantasy) and G (Tuning Knobs) unless workflow_overrides.tuning_knobs: true forces G. At full, walk all eight (A–H). At minimal, the GDD is optional — if authoring voluntarily, walk the standard set. Any system_overrides.<system> tier was already folded into the resolved tier in §1.

Walk through each required section in order. For each section, follow this cycle:

The Section Cycle

Context  ->  Questions  ->  Options  ->  Decision  ->  Draft  ->  Approval  ->  Write

1. Context: State what this section needs to contain, and surface any relevant decisions from dependency GDDs that constrain it.

2. Questions: Ask clarifying questions specific to this section. Use AskUserQuestion for constrained questions, conversational text for open-ended exploration.

3. Options: Where the section involves design choices (not just documentation), present 2-4 approaches with pros/cons. Explain reasoning in conversation text, then use AskUserQuestion to capture the decision.

4. Decision: User picks an approach or provides custom direction.

5. Draft: Write the section content in conversation text for review. Flag any provisional assumptions about undesigned dependencies.

6. Approval: Per the resolved modes.automation mode (.claude/docs/automation-modes.md):

   In collaborative mode: Immediately after the draft — in the SAME response — use AskUserQuestion. NEVER use plain text. NEVER skip this step.

   • Prompt: "Approve the [Section Name] section?"
   • Options: [A] Approve — write it to file / [B] Make changes — describe what to fix / [C] Start over

   The draft and the approval widget MUST appear together in one response. If the draft appears without the widget, the user is left at a blank prompt with no path forward — this is a protocol violation in collaborative mode.

   In guided mode: Write the section immediately after the draft with a brief one-line summary of what was decided. Skip the per-section widget; the multi-section authoring rule (no per-section confirmation) applies.

   In autonomous mode: Write the section directly and call log_decision with Decision point: Approve [Section Name] section, Chosen: [A] Approve, Category: minor.

7. Write: Use the Edit tool to replace the placeholder with the approved content. CRITICAL: Always include the section heading in the old_string to ensure uniqueness — never match [To be designed] alone, as multiple sections use the same placeholder and the Edit tool requires a unique match. Use this pattern:

   old_string: "## [Section Name]\n\n[To be designed]"
   new_string: "## [Section Name]\n\n[approved content]"
   

   Confirm the write.

8. Registry conflict check (Sections C and D only — Detailed Design and Formulas): After writing, scan the section content for entity names, item names, formula names, and numeric constants that appear in the registry. For each match:

   • Compare the value just written against the registry entry.
   • If they differ: surface the conflict immediately before starting the next section. Do not continue silently.

     "Registry conflict: [name] is registered in [source GDD] as [registry_value]. This section just wrote [new_value]. Which is correct?"

   • If new (not in registry): flag it as a candidate for registry registration (will be handled in Phase 5).

After writing each section, update production/session-state/active.md with the completed section name. Use Glob to check if the file exists — use Write to create it if absent, Edit to update it if present.

Section-Specific Guidance

Each section has unique design considerations and may benefit from specialist agents:

Section A: Overview

Goal: One paragraph a stranger could read and understand.

Derive recommended options before building the widget: Read the system's category and layer from the systems index (already in context from Phase 2), then determine the recommended option for each tab:

• Framing tab: keyed on the Category column (Core · Gameplay · Progression · Economy · Persistence · UI · Audio · Narrative · Meta). Player-facing — Gameplay, UI, Audio, Narrative → [C] Both recommended. Internal — Core, Persistence, Meta → [A] recommended. Mixed — Economy, Progression → [C] Both. Tiebreak, when Layer and Category disagree (a Foundation-layer Gameplay system is the common case): Category wins — the framing describes what the section is about, and a player-facing system stays player-facing wherever it sits in the dependency graph.
• ADR ref tab: Glob docs/architecture/adr-*.md and grep for the system name in the GDD Requirements section of any ADR. If a matching ADR is found → [A] Yes — cite the ADR recommended. If none found → [B] No recommended.
• Fantasy tab: Foundation/Infrastructure layer → [B] No recommended. All other categories → [A] Yes recommended.

Append (Recommended) to the appropriate option text in each tab.

Framing questions (ask BEFORE drafting): Use AskUserQuestion with a multi-tab widget:

• Tab "Framing" — "How should the overview frame this system?" Options: [A] As a data/infrastructure layer (technical framing) / [B] Through its player-facing effect (design framing) / [C] Both — describe the data layer and its player impact
• Tab "ADR ref" — "Should the overview reference the existing ADR for this system?" Options: [A] Yes — cite the ADR for implementation details / [B] No — keep the GDD at pure design level
• Tab "Fantasy" — "Does this system have a player fantasy worth stating?" Options: [A] Yes — players feel it directly / [B] No — pure infrastructure, players feel what it enables

Use the answers to shape the draft. In collaborative mode, do NOT answer these questions yourself and auto-draft — the widget must appear. In guided and autonomous, this is a MINOR framing decision: select the recommended option derived above, state it in one line, and proceed (that is the whole point of pre-deriving recommendations). Applies to every "ask BEFORE drafting" widget in this section walk, not just this one.

Questions to ask:

• What is this system in one sentence?
• How does a player interact with it? (active/passive/automatic)
• Why does this system exist — what would the game lose without it?

Cross-reference: Check that the description aligns with how the systems index describes it. Flag discrepancies.

Design vs. implementation boundary: Overview questions must stay at the behavior level — what the system does, not how it is built. If implementation questions arise during the Overview (e.g., "Should this use an Autoload singleton or a signal bus?"), note them as "→ becomes an ADR" and move on. Implementation patterns belong in /architecture-decision, not the GDD. The GDD describes behavior; the ADR describes the technical approach used to achieve it.

Section B: Player Fantasy

Goal: The emotional target — what the player should feel.

Derive recommended option before building the widget: Read the system's category and layer from Phase 2 context: Keyed on the Category column (Core · Gameplay · Progression · Economy · Persistence · UI · Audio · Narrative · Meta):

• Player-facing — Gameplay, UI, Audio, Narrative → [A] Direct recommended
• Internal — Core, Persistence, Meta → [B] Indirect recommended
• Mixed — Economy, Progression → [C] Both recommended

When Layer and Category disagree, Category wins — same tiebreak as the Framing tab above.

Append (Recommended) to the appropriate option text.

Framing question (ask BEFORE drafting): Use AskUserQuestion:

• Prompt: "Is this system something the player engages with directly, or infrastructure they experience indirectly?"
• Options: [A] Direct — player actively uses or feels this system / [B] Indirect — player experiences the effects, not the system / [C] Both — has a direct interaction layer and infrastructure beneath it

Use the answer to frame the Player Fantasy section appropriately. Do NOT assume the answer.

Questions to ask:

• What emotion or power fantasy does this serve?
• What reference games nail this feeling? What specifically creates it?
• Is this a "system you love engaging with" or "infrastructure you don't notice"?

Cross-reference: Must align with the game pillars. If the system serves a pillar, quote the relevant pillar text.

Review mode check (apply before spawning):

• solo → skip this agent spawn. Draft the section without the specialist. Add a note: "creative-director not consulted — Solo mode. Review manually before production."
• lean → skip unless this is a section with HIGH implementation risk (Sections D and H only). For other sections, draft without the agent.
• full → spawn as described below.

Agent delegation (MANDATORY): After the framing answer is given but before drafting, spawn creative-director via Agent:

• Provide: system name, framing answer (direct/indirect/both), game pillars, any reference games the user mentioned, the game concept summary
• Ask: "Shape the Player Fantasy for this system. What emotion or power fantasy should it serve? What player moment should we anchor to? What tone and language fits the game's established feeling? Be specific — give me 2-3 candidate framings."
• Collect the creative-director's framings and present them to the user alongside the draft.

Do NOT draft Section B without first consulting creative-director. The framing answer tells us what kind of fantasy it is; the creative-director shapes how it's described — tone, language, the specific player moment to anchor to.

Section C: Detailed Design (Core Rules, States, Interactions)

Goal: Unambiguous specification a programmer could implement without questions.

This is usually the largest section. Break it into sub-sections:

1. Core Rules: The fundamental mechanics. Use numbered rules for sequential processes, bullets for properties.
2. States and Transitions: If the system has states, map every state and every valid transition. Use a table.
3. Interactions with Other Systems: For each dependency (upstream and downstream), specify what data flows in, what flows out, and who owns the interface.

Questions to ask:

• Walk me through a typical use of this system, step by step
• What are the decision points the player faces?
• What can the player NOT do? (Constraints are as important as capabilities)

Review mode check (apply before spawning):

• solo → skip this agent spawn. Draft the section without the specialist. Add a note: "Specialist agents not consulted — Solo mode. Review manually before production."
• lean → skip unless this is a section with HIGH implementation risk (Sections D and H only). For other sections, draft without the agent.
• full → spawn as described below.

Agent delegation (MANDATORY): Before drafting Section C, spawn specialist agents via Agent in parallel:

• Look up the system category in the routing table (Section 6 of this skill)
• Spawn the Primary Agent AND Supporting Agent(s) listed for this category
• Provide each agent: system name, game concept summary, pillar set, dependency GDD excerpts, the specific section being worked on
• Collect their findings before drafting
• Surface any disagreements between agents to the user via AskUserQuestion
• Draft only after receiving specialist input

Do NOT draft Section C without first consulting the appropriate specialists. A systems-designer reviewing rules and mechanics will catch design gaps the main session cannot.

Cross-reference: For each interaction listed, verify it matches what the dependency GDD specifies. If a dependency defines a value or formula and this system expects something different, flag the conflict.

Section D: Formulas

Goal: Every mathematical formula, with variables defined, ranges specified, and edge cases noted.

Completion Steering — always begin each formula with this exact structure:

The [formula_name] formula is defined as:

`[formula_name] = [expression]`

**Variables:**
| Variable | Type | Range | Source | Description |
|----------|------|-------|--------|-------------|
| [name] | float/int | [min–max] | data file / calculated / constant | [what it represents] |

**Output Range:** [min] to [max] under normal play; [behaviour at extremes]
**Example:** [worked example with real numbers]

Do NOT write [Formula TBD] or describe a formula in prose without the variable table. A formula without defined variables cannot be implemented without guesswork.

These columns must match templates/game-design-document.md exactly. They did not: this block said Symbol where the template says Source, so a correctly-authored GDD was wrong against whichever of the two its reader happened to hold. Source is the column that stays, because it is what carries the coding-standards rule "gameplay values must be data-driven (external config), never hardcoded" into the design document — a variable marked data file is a tuning knob, one marked constant is a deliberate exception, and the distinction is invisible under a Symbol column. Put a symbol, where one helps, in the expression itself.

Questions to ask:

• What are the core calculations this system performs?
• Should scaling be linear, logarithmic, or stepped?
• What should the output ranges be at early/mid/late game?

Review mode check (apply before spawning):

• solo → skip this agent spawn. Draft the section without the specialist. Add a note: "systems-designer not consulted — Solo mode. Review manually before production."
• lean → skip unless this is a section with HIGH implementation risk (Sections D and H only). For other sections, draft without the agent.
• full → spawn as described below.

Agent delegation (MANDATORY): Before proposing any formulas or balance values, spawn specialist agents via Agent in parallel:

• Always spawn systems-designer: provide Core Rules from Section C, tuning goals from user, balance context from dependency GDDs. Ask them to propose formulas with variable tables and output ranges.
• For economy/cost systems, also spawn economy-designer: provide placement costs, upgrade cost intent, and progression goals. Ask them to validate cost curves and ratios.
• Present the specialists' proposals to the user for review via AskUserQuestion
• The user decides; the main session writes to file
• Do NOT invent formula values or balance numbers without specialist input. A user without balance design expertise cannot evaluate raw numbers — they need the specialists' reasoning.

Cross-reference: If a dependency GDD defines a formula whose output feeds into this system, reference it explicitly. Don't reinvent — connect.

Section E: Edge Cases

Goal: Explicitly handle unusual situations so they don't become bugs.

Completion Steering — format each edge case as:

• If [condition]: [exact outcome]. [rationale if non-obvious]

Example (adapt terminology to the game's domain):

• If [resource] reaches 0 while [protective condition] is active: hold at minimum until condition ends, then apply consequence.
• If two [triggers/events] fire simultaneously: resolve in [defined priority order]; ties use [defined tiebreak rule].

Do NOT write vague entries like "handle appropriately" — each must name the exact condition and the exact resolution. An edge case without a resolution is an open design question, not a specification.

Questions to ask:

• What happens at zero? At maximum? At out-of-range values?
• What happens when two rules apply at the same time?
• What happens if a player finds an unintended interaction? (Identify degenerate strategies)

Review mode check (apply before spawning):

• solo → skip this agent spawn. Draft the section without the specialist. Add a note: "systems-designer not consulted — Solo mode. Review manually before production."
• lean → skip unless this is a section with HIGH implementation risk (Sections D and H only). For other sections, draft without the agent.
• full → spawn as described below.

Agent delegation (MANDATORY): Spawn systems-designer via Agent before finalising edge cases. Provide: the completed Sections C and D, and ask them to identify edge cases from the formula and rule space that the main session may have missed. For narrative systems, also spawn narrative-director. Present their findings and ask the user which to include.

Cross-reference: Check edge cases against dependency GDDs. If a dependency defines a floor, cap, or resolution rule that this system could violate, flag it.

Section F: Dependencies

Goal: Map every system connection with direction and nature.

This section is partially pre-filled from the context gathering phase. Present the known dependencies from the systems index and ask:

• Are there dependencies I'm missing?
• For each dependency, what's the specific data interface?
• Which dependencies are hard (system cannot function without it) vs. soft (enhanced by it but works without it)?

Cross-reference: This section must be bidirectionally consistent. If this system lists "depends on Combat", then the Combat GDD should list "depended on by [this system]". Flag any one-directional dependencies for correction.

Section G: Tuning Knobs

Goal: Every designer-adjustable value, with safe ranges and extreme behaviors.

Questions to ask:

• What values should designers be able to tweak without code changes?
• For each knob, what breaks if it's set too high? Too low?
• Which knobs interact with each other? (Changing A makes B irrelevant)

Review mode check (apply before spawning):

• solo → skip this agent spawn. Derive the knobs from Section D's variable table yourself. Add a note: "systems-designer not consulted — Solo mode. Review manually before production."
• lean → skip unless Section D defines a formula whose knobs interact (changing one makes another inert).
• full → delegate as described below.

Agent delegation: If formulas are complex, delegate to systems-designer to derive tuning knobs from the formula variables.

The guard above was missing here while Sections B, C, D, E and H all carried one — and this delegation names systems-designer, the same agent Section D's guard has already told a solo run to skip. Read without it, solo skips the specialist for the formulas and then consults it for the knobs derived from those same formulas.

Cross-reference: If a dependency GDD lists tuning knobs that affect this system, reference them here. Don't create duplicate knobs — point to the source of truth.

Section H: Acceptance Criteria

Goal: Testable conditions that prove the system works as designed.

Completion Steering — format each criterion as Given-When-Then:

• GIVEN [initial state], WHEN [action or trigger], THEN [measurable outcome]

Example (adapt terminology to the game's domain):

• GIVEN [initial state], WHEN [player action or system trigger], THEN [specific measurable outcome].
• GIVEN [a constraint is active], WHEN [player attempts an action], THEN [feedback shown and action result].

Include at least: one criterion per core rule from Section C, and one per formula from Section D. Do NOT write "the system works as designed" — every criterion must be independently verifiable by a QA tester without reading the GDD.

When Section D was not authored (Formulas optional at this tier because the system defines no numeric rule), there are no formulas to cover and the criteria come from Section C alone — say so in one line rather than silently writing fewer criteria. If Section D was skipped but Section C states a quantity — a rate, threshold, cost or curve — that is the §1 test being met after the fact: stop, tell the user Formulas is required for this system, and author it before finalising the criteria. A criterion cannot verify a number the GDD never defines.

That escalation applies at standard only. It re-runs §1's conditional Formulas test, and §1 disables that conditional at minimal outright — "the conditional Formulas rule does NOT re-apply at minimal". At minimal a Section C quantity is expected and does not pull Formulas back in: state the value inline in Core Rules so it stays implementable, and move on. At full, Section D is unconditionally required, so the case cannot arise. Read without this scope, the two rules contradict each other for any minimal system that defines a rate — which is most of them.

Review mode check (apply before spawning):

• solo → skip this agent spawn. Draft the section without the specialist. Add a note: "qa-lead not consulted — Solo mode. Review manually before production."
• lean → skip unless this is a section with HIGH implementation risk (Sections D and H only). For other sections, draft without the agent.
• full → spawn as described below.

Agent delegation (MANDATORY): Spawn qa-lead via Agent before finalising acceptance criteria. Provide: the completed GDD sections C, D, E, and ask them to validate that the criteria are independently testable and cover all core rules and formulas. Surface any gaps or untestable criteria to the user.

Questions to ask:

• What's the minimum set of tests that prove this works?
• What performance budget does this system get? (frame time, memory)
• What would a QA tester check first?

Cross-reference: Include criteria that verify cross-system interactions work, not just this system in isolation.

Optional Sections: Visual/Audio, Game Feel, UI Requirements, Cross-References, Open Questions

These five are the template sections that are not among §1's eight. They are governed here, not by the tier: §1's per-tier lists decide the required set, and this block decides the rest independently. Adding a section here therefore never changes a tier's section count.

Visual/Audio and Game Feel are REQUIRED for some categories — not optional. Determine the requirement level before asking:

Keyed on the Category column of systems-index.md — the nine values templates/systems-index.md defines. Every one of the nine appears below exactly once, so nothing falls through:

Visual/Audio is REQUIRED (mandatory — do not offer to skip) for:

• Gameplay — combat, AI, stealth, movement, interaction: everything the player sees resolve
• UI — HUD, menus, inventory screens, dialogue UI
• Narrative — dialogue, quests, cutscenes, lore delivery
• Audio — by definition

Gameplay is the row this table was missing. It is the category /map-systems assigns to combat, AI and movement — the largest bucket in most action games. If it appears in neither this list nor the "all other" list below, the skill has no defined behaviour for it and the author has to guess. All nine categories must be covered between the two lists.

For required systems: spawn art-director via Agent before drafting this section. Provide: system name, game concept, game pillars, art bible sections 1–4 if they exist. Ask them to specify: (1) VFX and visual feedback requirements for this system's events, (2) any animation or visual style constraints, (3) which art bible principles most directly apply to this system. Present their output; do NOT leave this section as [To be designed] for visual systems.

Review mode check (apply before spawning):

• solo → skip this agent spawn. Draft the section without the specialist. Add a note: "art-director not consulted — Solo mode. Review manually before production."
• lean → skip unless this system's visual feedback is central to it (a Gameplay or UI system whose events the player reads to play). Otherwise draft without the agent.
• full → spawn as described above.

Sections B, C, D, E and H each carry this block and this spawn did not, while being worded as mandatory ("do NOT leave this section as [To be designed]"). Two agents in solo skipped it anyway, on the strength of the other five, and both flagged the guess. director-gates.md's "solo → no director gates anywhere" governs director gates, not specialist spawns, so it did not settle it — this block does.

Game Feel is REQUIRED (mandatory — do not offer to skip) for Gameplay and UI — the categories whose systems the player directly operates, where responsiveness, weight and snap are design targets rather than polish. It is optional for the other seven. The template argues the point itself: feel "drives animation budgets, input handling architecture, and hitbox timing. Retrofitting feel targets after implementation is expensive."

Cross-References is REQUIRED whenever the Dependencies section names another GDD. The rule is derived, not category-keyed: if this document references another system's mechanic, value or rule anywhere, that reference belongs in the table. Where Dependencies names nothing, write "None — this system references no other GDD" rather than leaving the placeholder. /review-all-gdds Phase 2c reads this table when it exists.

For the remaining five categories — Core, Progression, Economy, Persistence, Meta — Visual/Audio is optional: offer the optional sections after the required sections.

At minimal, force nothing. §1 says a voluntary minimal GDD is "exactly the 5 standard sections", which contradicts a category rule that makes Visual/Audio or Game Feel mandatory. §1 wins: at minimal both drop to optional and the whole set goes through the widget below. The contradiction is real — an agent authoring a minimal inventory GDD hit it and had to choose.

Use AskUserQuestion:

• "The required sections for this workflow tier are complete. Which of the remaining template sections do you want to define?"

  • Options: "All of them", "Just Cross-References and open questions", "Skip — I'll add these later"
  • List in the question only the ones still outstanding: Visual/Audio, Game Feel, UI Requirements, Cross-References, Open Questions minus any this system's category or dependencies already made mandatory above. Offering to skip a section the rules just made required is how a mandatory section gets skipped.
  • Recommended option: "All of them" when the system has any dependency, UI surface or player-facing feedback; "Just Cross-References and open questions" otherwise. autonomous needs a marked recommendation to pick — the three options previously carried none, unlike the Section A/B widgets, so an unattended run had nothing to choose by and defaulted to skipping.

  Do not state a section count here. The required set is tier-dependent (§1: 8 at full, 5 + conditional Formulas at standard, 5 at a voluntary minimal), so the previous hardcoded "8 required sections are complete" was false on every run below full — it told a standard-tier user that 8 sections existed when 6 had been authored.

For Visual/Audio (non-required systems): Coordinate with art-director and audio-director if detail is needed. Often a brief note suffices at the GDD stage.

Asset Spec Flag: After the Visual/Audio section is written with real content, output this notice: "📌 Asset Spec — Visual/Audio requirements are defined. After the art bible is approved, run /asset-spec system:[system-name] to produce per-asset visual descriptions, dimensions, and generation prompts from this section."

For UI Requirements: Coordinate with ux-designer for complex UI systems. After writing this section, check whether it contains real content (not just [To be designed] or a note that this system has no UI). If it does have real UI requirements, output this flag immediately:

📌 UX Flag — [System Name]: This system has UI requirements. In Phase 4 (Pre-Production), run /ux-design to create a UX spec for each screen or HUD element this system contributes to before writing epics. Stories that reference UI should cite design/ux/[screen].md, not the GDD directly.

Note this in the systems index for this system if you update it.

For Open Questions: Capture anything that came up during design that wasn't fully resolved. Each question should have an owner and target resolution date.

5. Post-Design Validation

After all sections are written:

5-pre: Author the Summary

Write ## Summary and its > **Quick reference** line now — after the design exists, so the summary distils real content rather than intentions. This runs at every tier, including standard and a voluntary minimal GDD: the Summary is what lets a later skill scan 20 GDDs and decide which to read in full (/create-epics, /architecture-review, /review-all-gdds all grep it), so a GDD without it silently forces those consumers back to full reads.

• Summary body: 2–3 sentences — what this system is, what it does for the player, why it exists in this game. No jargon; a reader who has not seen the GDD should learn whether it is relevant to their task.
• Quick reference: Layer and Priority from the systems index (design/gdd/systems-index.md); Key deps from the Dependencies section just written (system names, or None).

Replace the [To be designed] Summary placeholder in the skeleton. Then apply the section cycle's Write step as for any other section.

5a: Self-Check

Read back the complete GDD from file (not from conversation memory — the file is the source of truth). Verify:

• The ## Summary and its Quick reference are populated (not the placeholder)
• Every section required at this system's effective tier has real content (not placeholders) — §1: 8 at full, 5 + conditional Formulas at standard, 5 at a voluntary minimal. Do not verify against a fixed count of 8: below full that reports a correctly-authored GDD as incomplete, which is the same error already corrected in the optional-sections prompt above
• Formulas reference defined variables
• Edge cases have resolutions
• Dependencies are listed with interfaces
• Acceptance criteria are testable

5a-bis: Creative Director Pillar Review

Review mode check — apply before spawning CD-GDD-ALIGN:

• solo → skip. Note: "CD-GDD-ALIGN skipped — Solo mode." Proceed to Step 5b.
• lean → skip (not a PHASE-GATE). Note: "CD-GDD-ALIGN skipped — Lean mode." Proceed to Step 5b.
• full → spawn as normal.

Before finalizing the GDD, spawn creative-director via Agent using gate CD-GDD-ALIGN (.claude/docs/director-gates/cd-gdd-align.md).

Pass: completed GDD file path, game pillars (from design/gdd/game-concept.md or design/gdd/game-pillars.md), MDA aesthetics target.

Handle verdict per the standard rules in director-gates.md. After resolution, record the verdict in the GDD Status header: > **Creative Director Review (CD-GDD-ALIGN)**: APPROVED [date] / CONCERNS (accepted) [date] / REVISED [date]

5b: Update Entity Registry

Scan the completed GDD for cross-system facts that should be registered:

• Named entities (enemies, NPCs, bosses) with stats or drops
• Named items with values, weights, or categories
• Named formulas with defined variables and output ranges
• Named constants referenced by value in more than one place

First check the registry exists — §2a reads it "if it exists", and this step never carried the same guard. At standard and below the file is often absent, and a grep against a missing path returns nothing, which is indistinguishable from "no candidate is registered yet":

• Absent — say so, and ask whether to create it: "design/registry/entities.yaml does not exist. May I create it with these [N] entries?" If the user declines, skip 5b and say the registry was not written — do not treat the skip as a clean pass.
• Present but empty — every list is [], or the only matches are inside comment blocks. Treat it as present, register the candidates, but say which state you found: "registry exists and is empty — all [N] entries are new." The shipped template's comments carry fully-formed examples referencing design/gdd/inventory.md with real-looking values (base_inventory_slots: 20, gold_carry_limit: 9999), so §2a's prescribed grep referenced_by.*[system-name] returns comment lines on an empty registry — and §2d would then present those invented numbers to the user as "These values are locked." Match entries under a live entities:/items:/ formulas:/constants: key, never a commented example.
• Present — for each candidate, check whether it is already registered:

Grep pattern="  - name: [candidate_name]" path="design/registry/entities.yaml"

Present a summary:

Registry candidates from this GDD:
  NEW (not yet registered):
    - [entity_name] [entity]: [attribute]=[value], [attribute]=[value]
    - [item_name] [item]: [attribute]=[value], [attribute]=[value]
    - [formula_name] [formula]: variables=[list], output=[min–max]
  ALREADY REGISTERED (referenced_by will be updated):
    - [constant_name] [constant]: value=[N] ← matches registry ✅

Ask: "May I update design/registry/entities.yaml with these [N] new entries and update referenced_by for the existing entries?" (If the file was absent and the user approved creating it, the wording is create, not update, and there are no referenced_by arrays to merge.)

If yes: append new entries and update referenced_by arrays. Never modify existing value / attribute fields without surfacing it as a conflict first.

5c: Offer Design Review

Present a completion summary:

GDD Complete: [System Name]

• Sections written: [list]
• Provisional assumptions: [list any assumptions about undesigned dependencies]
• Cross-system conflicts found: [list or "none"]

To validate this GDD, open a fresh Claude Code session and run: /design-review design/gdd/[system-name].md

Never run /design-review in the same session as /design-system. The reviewing agent must be independent of the authoring context. Running it here would inherit the full design history, making independent critique impossible.

NEVER offer to run /design-review inline. Always direct the user to a fresh window.

5d: Update Systems Index

After the GDD is complete (and optionally reviewed):

First check the systems index exists. §2a skips it at minimal because it is never written at that tier, and this step never carried the same guard — the same class of bug §5b was patched for. It bites hardest on a minimal project with a system_overrides bump, where the effective tier is standard or full and nothing else in §5 hints the file may be absent.

• Absent — say so in one line ("no design/gdd/systems-index.md at this workflow tier; nothing to update") and skip to §5e. Do not offer to create one: /map-systems owns that file, and a stub written here would be a systems index listing exactly one system.

• Present — continue:

• Read the systems index

• Update the target system's row:

  • If design-review was run and verdict is APPROVED: Status → "Approved"
  • If design-review was run and verdict is NEEDS REVISION: Status → "In Review"
  • If design-review was skipped: Status → "Designed" (pending review)
  • If the user chose "I'll review it myself first": Status → "Designed"
  • Design Doc: link to design/gdd/[system-name].md

• Update the Progress Tracker counts

Ask: "May I update the systems index at design/gdd/systems-index.md?"

5e: Update Session State

Update production/session-state/active.md with:

• Task: [system-name] GDD
• Status: Complete (or In Review if design-review was run)
• File: design/gdd/[system-name].md
• Sections: [list the sections actually authored, by name] — never a fixed count; §5a forbids verifying against /8, and the same reasoning applies to recording it. Below full a correctly-authored GDD has fewer than 8 sections, and writing "All 8 written" into session state makes the next reader believe a complete GDD is incomplete
• Next: [suggest next system from design order]

5f: Suggest Next Steps

Use AskUserQuestion:

• "What's next?"
  • Options:
    • "Run /consistency-check — verify this GDD's values don't conflict with existing GDDs (recommended before designing the next system)"
    • "Design next system ([next-in-order])" — if undesigned systems remain
    • "Fix review findings" — if design-review flagged issues
    • "Stop here for this session"
    • "Run /gate-check" — if enough MVP systems are designed

6. Specialist Agent Routing

This skill delegates to specialist agents for domain expertise. The main session orchestrates the overall flow; agents provide expert content.

Rows here are finer-grained than the nine Category values on purpose — the right specialist for combat is not the right specialist for pathfinding, and both are Gameplay. Resolve in two steps: take the system's Category from systems-index.md, then pick the row within it that matches what the system actually does. Every category has at least one row, so nothing falls through.

If two rows fit, spawn the union of their Primary agents and say why.

When delegating via the Agent tool:

• Provide: system name, game concept summary, dependency GDD excerpts, the specific section being worked on, and what question needs expert input
• The agent returns analysis/proposals to the main session
• The main session presents the agent's output to the user via AskUserQuestion
• The user decides; the main session writes to file
• Agents do NOT write to files directly — the main session owns all file writes

7. Recovery & Resume

If the session is interrupted (compaction, crash, new session):

1. Read production/session-state/active.md — it records the current system and which sections are complete
2. Read design/gdd/[system-name].md — sections with real content are done; sections with [To be designed] still need work
3. Resume from the next incomplete section — no need to re-discuss completed ones

This is why incremental writing matters: every approved section survives any disruption.

Collaborative Protocol

In collaborative mode (the default). For guided and autonomous modes, see the per-mode rules in .claude/docs/automation-modes.md — the "Never" lines below describe what collaborative mode requires, not what applies universally.

This skill follows the collaborative design principle at every step:

1. Question -> Options -> Decision -> Draft -> Approval for every section
2. AskUserQuestion at every decision point (Explain -> Capture pattern):
   • Phase 2: "Ready to start, or need more context?"
   • Phase 3: "May I create the skeleton?"
   • Phase 4 (each section): Design questions, approach options, draft approval
   • Phase 5: "May I update the entity registry? May I update the systems index? What's next?" — not "Run design review?": §5c forbids offering /design-review inline, because the reviewing agent must not inherit this session's design history. Phase 5c presents the hand-off; it never asks.
3. "May I write to [filepath]?" before the skeleton and before each section write
4. Incremental writing: Each section is written to file immediately after approval
5. Session state updates: After every section write
6. Cross-referencing: Every section checks existing GDDs for conflicts
7. Specialist routing: Complex sections get expert agent input, presented to the user for decision — never written silently

Never auto-generate the full GDD and present it as a fait accompli. Never write a section without user approval. Never contradict an existing approved GDD without flagging the conflict. Always show where decisions come from (dependency GDDs, pillars, user choices).

Context Window Awareness

This is a long-running skill. After writing each section, check if the status line shows context at or above 70%. If so, append this notice to the response:

Context is approaching the limit (≥70%). Your progress is saved — all approved sections are written to design/gdd/[system-name].md. When you're ready to continue, open a fresh Claude Code session and run /design-system [system-name] — it will detect which sections are complete and resume from the next one.

Recommended Next Steps

• Run /design-review design/gdd/[system-name].md in a fresh session to validate the completed GDD independently
• Run /consistency-check to verify this GDD's values don't conflict with other GDDs
• Run /map-systems next to move to the next highest-priority undesigned system
• Run /gate-check pre-production when all MVP GDDs are authored and reviewed