---
paths:
  - "design/gdd/**"
---

# Design Document Rules

- The 8 GDD sections are: Overview, Player Fantasy, Detailed Rules, Formulas, Edge Cases, Dependencies, Tuning Knobs, Acceptance Criteria
- **How many are required depends on `modes.workflow`** — all 8 at `full`, 5 (+ Formulas when the system **defines numeric rules**: rates, curves, thresholds, costs, damage, drop weights — anything a balance pass would tune) at `standard`, none at `minimal` (the design record there is `design/game-brief.md`). Resolve the tier before flagging a section as missing; see `.claude/docs/workflow-modes.md`
- **The Formulas test is what the system defines, not what it is called.** A system's `Category` in `systems-index.md` is a hint — `Gameplay`, `Economy` and `Progression` almost always qualify — never the test. Do not gate Formulas on a category token: the categories `/map-systems` writes (`Core · Gameplay · Progression · Economy · Persistence · UI · Audio · Narrative · Meta`) do not include `combat` or `AI`, which are example systems *within* `Gameplay`. Every site stating this rule must state the same test.
- **Section-name alias**: The GDD template and `/design-system` author this section as `## Detailed Design`; the design standard calls it **Detailed Rules**. These are the SAME required section — accept either heading and never rewrite one into the other.
- Formulas must include variable definitions, expected value ranges, and example calculations
- Edge cases must explicitly state what happens, not just "handle gracefully"
- Dependencies must be bidirectional — if system A depends on B, B's doc must mention A
- Tuning knobs must specify safe ranges and what gameplay aspect they affect
- Acceptance criteria must be testable — a QA tester must be able to verify pass/fail
- No hand-waving: "the system should feel good" is not a valid specification
- Balance values must link to their source formula or rationale
- Design documents MUST be written incrementally: create skeleton first, then fill
  each section one at a time with user approval between sections. Write each
  approved section to the file immediately to persist decisions and manage context