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# Content Moderation & Age Verification Architecture
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> **Status:** Proposed
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> **Owner:** Platform team
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> **Related:** Server authority + client prediction, avatar component system, backend auth (JWT)
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## 1. Overview
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This document specifies the **content moderation** and **age verification**
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architecture for **agp-game**, a Godot-based multiplayer game built by
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autonomous agents. It defines:
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- How **content flags** propagate through the system across the three primary
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content types: **assets**, **rooms**, and **scripts**.
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- How flags are **evaluated, aggregated, and enforced** at load time, at
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runtime, and at the network boundary.
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- The **age verification flow**, combining a lightweight **self-declaration**
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with an optional **ID check hook** for higher-assurance verification.
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The goal is a **single, consistent moderation pipeline** that applies the same
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rules to user-generated content (UGC) regardless of whether it is a 3D asset, a
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room definition, or a script, and that gates access to mature content behind a
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verifiable age gate.
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### 1.1 Design Goals
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- **Uniformity:** One flag vocabulary and one propagation mechanism across
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assets, rooms, and scripts.
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- **Composability:** Flags on a room aggregate the flags of the assets and
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scripts it contains; flags on a world aggregate the flags of its rooms.
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- **Enforcement at the boundary:** The server is authoritative for what content
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a client may load or receive, mirroring the server-authoritative networking
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model.
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- **Privacy-preserving age checks:** Self-declaration requires no PII; the ID
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check hook is optional, pluggable, and never stores raw identity documents.
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- **Auditability:** Every flag decision is logged with a reason, an actor, and
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a timestamp so moderation actions are reviewable.
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---
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## 2. Content Flag Vocabulary
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All content carries a set of **content flags**. A flag is a typed, immutable
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label with a **severity** and a **scope**. Flags are the atomic unit of
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moderation; everything else (aggregation, enforcement, gating) operates on
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flags.
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### 2.1 Flag Definition
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A flag is a structured record:
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| Field | Type | Description |
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|------------|-----------|--------------------------------------------------------------------------|
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| `id` | `string` | Stable machine-readable identifier, e.g. `violence.gore`. |
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| `label` | `string` | Human-readable name, e.g. "Graphic Gore". |
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| `category` | `enum` | One of `violence`, `sexual`, `language`, `substance`, `gambling`, `horror`, `hate`, `custom`. |
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| `severity` | `enum` | One of `none`, `mild`, `moderate`, `severe`. |
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| `scope` | `enum` | One of `visual`, `audio`, `text`, `behavior`, `interaction`. |
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| `mature` | `bool` | Whether this flag triggers the age gate (see §5). |
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| `reason` | `string` | Free-text justification supplied by the flagger. |
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| `source` | `enum` | One of `author`, `moderator`, `automated`, `community`. |
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### 2.2 Canonical Flag Set
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The platform defines a **canonical registry** of flags so that different
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content types and different flaggers use the same vocabulary. Examples:
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| id | category | severity | scope | mature |
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|-----------------------------|------------|-----------|--------------|--------|
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| `violence.none` | violence | none | visual | false |
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| `violence.mild` | violence | mild | visual | false |
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| `violence.gore` | violence | severe | visual | true |
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| `sexual.suggestive` | sexual | mild | visual | true |
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| `sexual.explicit` | sexual | severe | visual | true |
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| `language.mild` | language | mild | text | false |
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| `language.profanity` | language | moderate | text | false |
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| `substance.references` | substance | mild | text | false |
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| `gambling.simulated` | gambling | moderate | behavior | true |
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| `horror.jumpscare` | horror | mild | audio/visual | false |
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| `hate.hateful` | hate | severe | text | true |
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The registry is **data-driven** (a JSON/YAML manifest shipped with the server)
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so new flags can be added without code changes.
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---
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## 3. Flag Propagation Model
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Flags propagate through the system along the **content dependency graph**. The
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three content types form a hierarchy:
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```
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World
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└── Room
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├── Asset (mesh, texture, audio, animation, material)
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└── Script (behavior, dialogue, event logic)
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```
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### 3.1 Propagation Rules
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1. **Explicit flags** are set directly on a content item by its author or a
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moderator.
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2. **Inherited flags** flow upward: a room's effective flag set is the **union**
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of its own explicit flags and the flags of every asset and script it
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references.
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3. **Aggregation** uses the **maximum severity** per category across all
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contributing items. A room containing one `violence.gore` asset and one
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`violence.none` asset is `violence.severe`.
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4. **Maturity is monotonic:** if any contributing item is `mature`, the
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containing room and world are `mature`.
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5. **Cycles are impossible** by construction: content references form a DAG
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(an asset cannot contain a room; a room cannot contain itself).
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### 3.2 Propagation Through the Pipeline
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Flags are attached at **authoring time** and carried through every stage:
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```
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Authoring ──► Upload ──► Validation ──► Storage ──► Distribution ──► Runtime
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│ │ │ │ │ │
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│ flag │ flag │ automated │ flag │ flag │ flag
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│ declared │ preserved │ scan adds │ indexed │ re-checked │ enforced
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│ │ │ flags │ │ │
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```
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| Stage | Responsibility |
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|--------------|-------------------------------------------------------------------------|
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| **Authoring**| Author declares flags in the editor/upload UI. |
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| **Upload** | Flags are validated against the canonical registry; unknown flags rejected. |
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| **Validation**| Automated scanner (hash-based + heuristic) adds flags for detected content. |
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| **Storage** | Flags are stored alongside the content record and indexed for queries. |
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| **Distribution**| Flags are re-checked against the current registry before serving. |
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| **Runtime** | The client enforces flags before loading content (see §4). |
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### 3.3 Data Model
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Flags are stored as a **normalized join table** so they can be queried and
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aggregated efficiently:
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```
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content_item (id, type, owner_id, ...)
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content_flag (content_id, flag_id, source, reason, created_at, actor_id)
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flag_registry (id, category, severity, scope, mature, ...)
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```
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Aggregation is computed by a SQL view / query that joins a content item's
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transitive dependencies. Because the graph is a DAG, this is a bounded
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recursive query (PostgreSQL `WITH RECURSIVE`).
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---
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## 4. Enforcement
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Enforcement happens at three layers, in order:
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### 4.1 Load-Time Enforcement (Server)
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Before a client is allowed to **request** content, the server evaluates the
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content's effective flag set against the requesting account's **content
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preferences** and **age verification status**:
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- If the content is `mature` and the account is **not age-verified**, the
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request is **rejected** with a `403 MATURE_CONTENT_REQUIRES_VERIFICATION`.
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- If the content's flags exceed the account's **content filter** (a per-account
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severity threshold per category), the request is rejected or the offending
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content is **stripped** (e.g., audio muted, mesh hidden, script not loaded).
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### 4.2 Runtime Enforcement (Client)
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The client receives a **manifest** of allowed content from the server. It never
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loads content that is not in the manifest. This prevents a malicious or buggy
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client from bypassing the server's filter by loading content directly.
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- Assets not in the manifest are **not instantiated**.
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- Scripts not in the manifest are **not executed**.
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- Rooms not in the manifest are **not entered**.
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### 4.3 Network Boundary Enforcement
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The server **filters replication** based on flags:
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- Mature or filtered content is **not replicated** to clients that cannot
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receive it.
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- A room's flag set is broadcast in the room metadata so clients can show a
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warning before entry.
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### 4.4 Enforcement Decision Flow
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```
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Client requests content C for account A
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│
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▼
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Compute effective flags F(C) [union + max-severity aggregation]
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│
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▼
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Is A age-verified? ──no──► Is F(C).mature? ──yes──► REJECT (403)
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│ yes │ no
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▼ ▼
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Does F(C) exceed A's filter? ──► yes ──► REJECT or STRIP
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│ no
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▼
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Serve content + manifest
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```
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---
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## 5. Age Verification Flow
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Age verification is a **two-tier** system:
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- **Tier 1 — Self-declaration:** The user asserts their date of birth. This is
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fast, requires no PII beyond a birthdate, and is sufficient for most content.
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- **Tier 2 — ID check (optional hook):** A pluggable identity-verification
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provider confirms the user is an adult. This raises the account's assurance
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level and unlocks the highest maturity tier.
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### 5.1 Verification States
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An account has an **age verification status**:
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| Status | Meaning |
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|-------------------|----------------------------------------------------------------------|
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| `unverified` | No declaration on file. |
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| `self_declared` | User declared a birthdate; **not** independently confirmed. |
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| `id_verified` | User passed the ID check hook; independently confirmed adult. |
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| `rejected` | ID check failed or declaration was inconsistent. |
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### 5.2 Tier 1 — Self-Declaration Flow
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```
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User submits { date_of_birth }
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│
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▼
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Server validates format & plausibility (age 13–120, not in future)
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│
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▼
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Compute age from DOB
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│
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▼
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age >= 18 ──► status = self_declared (adult)
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age >= 13 ──► status = self_declared (minor, restricted)
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age < 13 ──► status = rejected (below minimum platform age)
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```
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- The DOB is stored **encrypted at rest** and is **never exposed** to other
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players.
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- A user may **upgrade** from `self_declared` to `id_verified` at any time via
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Tier 2.
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### 5.3 Tier 2 — ID Check Hook
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The ID check is an **optional, pluggable hook**. The platform defines an
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interface; concrete providers (e.g., a third-party KYC service) implement it.
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```
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User requests ID verification
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│
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▼
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Server creates a verification session (idempotent, expiring)
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│
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▼
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Server calls provider hook: verify(identity_token) -> { adult: bool, ref: string }
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│
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▼
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adult == true ──► status = id_verified, store provider ref (not raw doc)
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adult == false ─► status = rejected
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provider error ──► status unchanged, retry allowed
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```
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**Privacy guarantees:**
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- The platform **never stores** the raw identity document or image.
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- Only the provider's **opaque reference** and the boolean `adult` result are
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persisted.
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- The hook is **asynchronous and idempotent**; a session can be retried without
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double-charging or double-verifying.
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### 5.4 Hook Interface
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The ID check hook is defined as a backend interface (FastAPI dependency /
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abstract service):
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```python
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class IdentityVerificationProvider(Protocol):
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def create_session(self, user_id: str) -> VerificationSession: ...
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def verify(self, session_id: str, identity_token: str) -> VerificationResult: ...
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class VerificationResult:
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adult: bool
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provider_ref: str | None
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error: str | None
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```
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A default **no-op provider** returns `adult=False` with a clear error, so the
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system runs without any third-party integration until one is configured.
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### 5.5 Age Gate Enforcement
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The age gate is enforced at **load time** (see §4.1):
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| Verification status | Can access `mature` content? |
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|---------------------|------------------------------|
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| `unverified` | No |
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| `self_declared` | Yes (adult) / No (minor) |
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| `id_verified` | Yes |
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| `rejected` | No |
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---
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## 6. Moderation Workflow
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### 6.1 Flagging Sources
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Content can be flagged by:
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- **Author** (self-declared at upload).
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- **Automated scanner** (hash-based detection, heuristic analysis).
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- **Community** (players report content; reports become flags after review).
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- **Moderator** (manual review and override).
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### 6.2 Review Queue
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Community and automated flags enter a **review queue**. A moderator either:
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- **Approves** the flag (it becomes authoritative), or
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- **Rejects** the flag (it is discarded), or
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- **Escalates** to a senior moderator for severe/hate flags.
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### 6.3 Actions
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Once a flag is authoritative, a moderator can take actions:
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| Action | Effect |
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|-----------------|---------------------------------------------------------------|
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| `warn` | Notify the author; content remains. |
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| `restrict` | Content hidden from users below a filter threshold. |
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| `age_gate` | Content marked `mature`; requires age verification. |
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| `remove` | Content taken down; not served. |
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| `ban_author` | Author's upload privileges suspended. |
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### 6.4 Audit Log
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Every flag and action is written to an **audit log**:
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```
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audit_event (id, content_id, actor_id, action, flag_id, reason, created_at)
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```
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This log is append-only and used for transparency and dispute resolution.
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---
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## 7. Client-Side Integration (Godot)
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### 7.1 Content Manifest
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The server sends each client a **content manifest** — the set of content the
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client is permitted to load, derived from the account's verification status and
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filter. The Godot client:
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- Loads only manifest-listed assets.
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- Executes only manifest-listed scripts.
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- Shows a **maturity warning** dialog before entering a room whose effective
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flags include `mature` content.
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### 7.2 Flag Metadata on Content
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Each content resource carries a `content_flags` metadata field (a Godot
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`Dictionary` or custom `Resource`). The client uses this for local UI decisions
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(e.g., showing a warning icon) but **never** as the authority for whether to
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load — the server manifest is authoritative.
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### 7.3 Age Verification UI
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The client exposes an **age verification screen**:
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- Tier 1: a date-of-birth picker.
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- Tier 2: a button that opens the ID check provider flow (deep link / webview).
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The client calls the backend endpoints (§8) and reflects the resulting status.
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---
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## 8. Backend API Surface
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| Method | Path | Description |
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|--------|-----------------------------------|------------------------------------------------|
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| `POST` | `/v1/age/declare` | Submit self-declared DOB (Tier 1). |
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| `POST` | `/v1/age/verify/session` | Create an ID-check session (Tier 2). |
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| `POST` | `/v1/age/verify/confirm` | Confirm an ID-check session with a token. |
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| `GET` | `/v1/age/status` | Return the account's verification status. |
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| `GET` | `/v1/content/{id}/flags` | Return a content item's effective flags. |
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| `POST` | `/v1/content/{id}/flags` | Add a flag (author/community). |
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| `POST` | `/v1/moderation/review/{flag_id}` | Moderator approve/reject/escalate. |
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| `POST` | `/v1/moderation/action` | Apply a moderation action. |
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| `GET` | `/v1/manifest` | Return the client's permitted content manifest.|
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All endpoints require a valid **JWT** (matching the existing auth stack). The
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age endpoints additionally require the account to be in a non-`rejected` state.
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---
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## 9. Security & Privacy Considerations
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- **DOB encryption:** Self-declared birthdates are encrypted at rest; only the
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derived age and verification status are used in authorization decisions.
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- **No raw identity storage:** The ID check hook persists only a provider
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reference and a boolean result.
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- **Server authority:** The client manifest prevents bypass; the client never
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trusts its own flag metadata for access decisions.
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- **Rate limiting:** Age-declaration and ID-check endpoints are rate-limited to
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prevent abuse and enumeration.
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- **Auditability:** All flag and verification events are logged append-only.
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---
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## 10. Open Questions / Future Work
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- **Regional age thresholds:** Different jurisdictions may require different
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minimum ages; the threshold should be configurable per region.
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- **Parental controls:** A future feature may let a parent set a content filter
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on a minor's account.
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- **Automated scanner accuracy:** The heuristic scanner may produce false
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positives; a confidence score should be attached to automated flags.
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- **Offline / local content:** How flags apply to locally-authored content that
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is never uploaded remains to be defined.
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@@ -1,683 +0,0 @@
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# World Chunk Data Format & Persistence Architecture
|
||||
|
||||
> **Status:** Proposed
|
||||
> **Owner:** Platform team
|
||||
> **Related:** Server authority + client prediction, avatar component system, content moderation & age verification, backend auth (JWT)
|
||||
|
||||
## 1. Overview
|
||||
|
||||
This document specifies the **world chunk data format** and **persistence
|
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schema** for **agp-game**, a Godot-based multiplayer game built by autonomous
|
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agents. It defines:
|
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|
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- The **chunk data format** — both a human-readable **JSON** form (for
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authoring, tooling, and debugging) and a compact **binary** form (for
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runtime loading and network transfer).
|
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- The **SQLite schema** that persists world state on the server, including
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chunk metadata, chunk payloads, and the world/room hierarchy.
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- The **read/write API** that the server and client use to load, save, and
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stream chunks.
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The goal is a **single, versioned chunk contract** that is shared across the
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Godot client, the Python backend, and the persistence layer. A chunk is the
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atomic unit of world geometry, gameplay objects, and persistence — the server
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loads and saves whole chunks, and clients stream the chunks around them.
|
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|
||||
### 1.1 Design Goals
|
||||
|
||||
- **Versioned & forward-compatible:** Every chunk carries a format version so
|
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the loader can migrate old data and reject unknown future data gracefully.
|
||||
- **Dual representation:** JSON for authoring/debugging, binary for
|
||||
runtime/network. Both encode the *same* logical model so there is exactly one
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source of truth for the schema.
|
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- **Server-authoritative persistence:** The server is the only writer to the
|
||||
SQLite store. Clients submit *edits* (deltas) and the server applies and
|
||||
persists them, mirroring the server-authoritative networking model.
|
||||
- **Chunk-granular persistence:** Persistence happens at chunk granularity so
|
||||
the server can save a dirty chunk without rewriting the whole world, and can
|
||||
stream only the chunks a client needs.
|
||||
- **Deterministic & testable:** The binary format is byte-stable for a given
|
||||
logical payload, enabling checksums, caching, and reproducible tests.
|
||||
- **Moderation-aware:** Chunks reference content (assets, scripts) that carry
|
||||
content flags (see `content_moderation.md`); the persistence layer stores the
|
||||
moderation state alongside chunk data so enforcement can happen at load time.
|
||||
|
||||
---
|
||||
|
||||
## 2. World Model & Chunking
|
||||
|
||||
### 2.1 World Hierarchy
|
||||
|
||||
The world is organized as a hierarchy that matches the moderation content graph:
|
||||
|
||||
```
|
||||
World
|
||||
└── Room
|
||||
└── Chunk (the atomic persistence & streaming unit)
|
||||
├── Tiles / Terrain
|
||||
├── Static objects (props, geometry)
|
||||
├── Dynamic objects (spawnable entities, interactables)
|
||||
└── Metadata (flags, version, timestamps)
|
||||
```
|
||||
|
||||
- A **World** is the top-level container (a named, versioned space).
|
||||
- A **Room** is a bounded region within a world (a level, a building, a zone).
|
||||
- A **Chunk** is a fixed-size, axis-aligned region of a room. It is the unit of
|
||||
load, save, and stream.
|
||||
|
||||
### 2.2 Chunk Dimensions
|
||||
|
||||
Chunks are **fixed-size, axis-aligned boxes** in world space. The default
|
||||
dimensions are a configuration constant so they can be tuned per world:
|
||||
|
||||
| Constant | Default | Description |
|
||||
|---------------------|---------|----------------------------------------------------|
|
||||
| `CHUNK_SIZE_X` | 32 | Chunk width in world units (tiles). |
|
||||
| `CHUNK_SIZE_Y` | 32 | Chunk height in world units (tiles). |
|
||||
| `CHUNK_SIZE_Z` | 1 | Chunk depth (1 = flat 2D world; >1 = volumetric). |
|
||||
| `CHUNK_ORIGIN` | `(0,0)` | World-space origin of chunk coordinate `(0,0)`. |
|
||||
|
||||
A chunk is identified by its **integer chunk coordinate** `(cx, cy, cz)`,
|
||||
computed from a world-space position `p` as:
|
||||
|
||||
```
|
||||
cx = floor((p.x - CHUNK_ORIGIN.x) / CHUNK_SIZE_X)
|
||||
cy = floor((p.y - CHUNK_ORIGIN.y) / CHUNK_SIZE_Y)
|
||||
cz = floor((p.z - CHUNK_ORIGIN.z) / CHUNK_SIZE_Z)
|
||||
```
|
||||
|
||||
The chunk's world-space bounding box is therefore:
|
||||
|
||||
```
|
||||
min = (CHUNK_ORIGIN.x + cx*CHUNK_SIZE_X, ...)
|
||||
max = min + (CHUNK_SIZE_X, CHUNK_SIZE_Y, CHUNK_SIZE_Z)
|
||||
```
|
||||
|
||||
### 2.3 Chunk Coordinate Key
|
||||
|
||||
For storage and lookup, a chunk is addressed by a **canonical string key**:
|
||||
|
||||
```
|
||||
"{world_id}:{room_id}:{cx}:{cy}:{cz}"
|
||||
```
|
||||
|
||||
Example: `"w_0001:r_0001:12:-4:0"`. This key is the primary lookup key in the
|
||||
SQLite `chunks` table and is used in the read/write API.
|
||||
|
||||
---
|
||||
|
||||
## 3. Chunk Data Format
|
||||
|
||||
### 3.1 Logical Model
|
||||
|
||||
Both the JSON and binary encodings serialize the same logical chunk model. The
|
||||
logical model is defined here once; the two encodings are projections of it.
|
||||
|
||||
```
|
||||
Chunk
|
||||
├── version : uint (format version, currently 1)
|
||||
├── key : string (canonical chunk key, see §2.3)
|
||||
├── world_id : string
|
||||
├── room_id : string
|
||||
├── coord : { cx, cy, cz } (int)
|
||||
├── bounds : { min_x, min_y, min_z, max_x, max_y, max_z } (float)
|
||||
├── tiles : TileLayer[] (terrain / tile data)
|
||||
├── objects : WorldObject[] (static + dynamic objects)
|
||||
├── flags : ContentFlags (moderation flags, see §3.5)
|
||||
├── meta : { created_at, updated_at, revision, author }
|
||||
└── checksum : string (SHA-256 of canonical payload)
|
||||
```
|
||||
|
||||
### 3.2 Tile Layer
|
||||
|
||||
A chunk's terrain is stored as one or more **tile layers**. Each layer is a
|
||||
dense grid of tile IDs of size `CHUNK_SIZE_X × CHUNK_SIZE_Y` (× `CHUNK_SIZE_Z`
|
||||
for volumetric worlds).
|
||||
|
||||
```
|
||||
TileLayer
|
||||
├── name : string (e.g. "ground", "walls", "decor")
|
||||
├── layer_id : uint
|
||||
├── width : uint (= CHUNK_SIZE_X)
|
||||
├── height : uint (= CHUNK_SIZE_Y)
|
||||
├── depth : uint (= CHUNK_SIZE_Z)
|
||||
├── tiles : uint[] (flattened tile IDs, row-major, length = w*h*d)
|
||||
└── palette : TileDef[] (tile ID → tile definition, shared per layer)
|
||||
```
|
||||
|
||||
**Tile encoding:** A tile ID is a `uint16` index into the layer's `palette`.
|
||||
`0` is reserved for "empty/air". The palette maps each tile ID to a `TileDef`:
|
||||
|
||||
```
|
||||
TileDef
|
||||
├── id : uint16
|
||||
├── asset_id : string (reference to a tile/terrain asset)
|
||||
├── solid : bool (collision)
|
||||
├── flags : uint32 (bitmask: walkable, climbable, liquid, ...)
|
||||
└── variants : uint8 (number of visual variants for this tile)
|
||||
```
|
||||
|
||||
**Rationale for palette + indices:** Storing dense `uint16` indices rather than
|
||||
full asset strings per cell keeps the binary payload small (2 bytes/cell) while
|
||||
the palette (shared across the layer) carries the rich per-tile metadata.
|
||||
|
||||
### 3.3 World Objects
|
||||
|
||||
Objects are the non-tile entities in a chunk: static props, interactables,
|
||||
spawn points, and dynamic-object templates.
|
||||
|
||||
```
|
||||
WorldObject
|
||||
├── id : string (stable object id, unique within the chunk)
|
||||
├── type : string (e.g. "prop", "interactable", "spawn_point", "door")
|
||||
├── asset_id : string (reference to the object's mesh/glTF asset)
|
||||
├── transform : { pos: [x,y,z], rot: [x,y,z,w], scale: [x,y,z] }
|
||||
├── properties : object (type-specific key/value map, JSON-typed)
|
||||
├── dynamic : bool (true if this is a spawnable dynamic entity)
|
||||
└── flags : ContentFlags (per-object moderation flags)
|
||||
```
|
||||
|
||||
**Dynamic objects** are stored as *templates* in the chunk. Their *runtime
|
||||
state* (position, health, inventory) is **not** stored in the chunk; it lives
|
||||
in the runtime entity store and is persisted separately (see §4.4). This keeps
|
||||
chunks stable and diffable — a chunk only changes when its *static* content
|
||||
changes.
|
||||
|
||||
### 3.4 Content Flags
|
||||
|
||||
Each chunk (and each object) carries a **content flag set** that is the
|
||||
aggregate of the moderation flags of the assets and scripts it references. This
|
||||
mirrors the aggregation rules in `content_moderation.md`:
|
||||
|
||||
```
|
||||
ContentFlags
|
||||
├── categories : { violence, sexual, language, substance, gambling, horror, hate, custom }
|
||||
│ (each → severity: none|mild|moderate|severe)
|
||||
├── mature : bool (true if any contributing item is mature)
|
||||
└── sources : string[] (flag ids that contributed, for audit)
|
||||
```
|
||||
|
||||
The server computes and persists these flags at write time so that enforcement
|
||||
(age gating, content filtering) can happen at load time without re-scanning
|
||||
assets.
|
||||
|
||||
### 3.5 JSON Encoding
|
||||
|
||||
The JSON encoding is the **authoring and debugging** representation. It is
|
||||
human-readable, diffable, and used by tools and tests. It is the canonical
|
||||
logical model serialized directly.
|
||||
|
||||
```json
|
||||
{
|
||||
"version": 1,
|
||||
"key": "w_0001:r_0001:12:-4:0",
|
||||
"world_id": "w_0001",
|
||||
"room_id": "r_0001",
|
||||
"coord": { "cx": 12, "cy": -4, "cz": 0 },
|
||||
"bounds": { "min_x": 384.0, "min_y": -128.0, "min_z": 0.0,
|
||||
"max_x": 416.0, "max_y": -96.0, "max_z": 1.0 },
|
||||
"tiles": [
|
||||
{
|
||||
"name": "ground",
|
||||
"layer_id": 0,
|
||||
"width": 32,
|
||||
"height": 32,
|
||||
"depth": 1,
|
||||
"palette": [
|
||||
{ "id": 0, "asset_id": "", "solid": false, "flags": 0, "variants": 1 },
|
||||
{ "id": 1, "asset_id": "tiles/grass", "solid": false, "flags": 1, "variants": 4 }
|
||||
],
|
||||
"tiles": [0, 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 0, 1, 1]
|
||||
}
|
||||
],
|
||||
"objects": [
|
||||
{
|
||||
"id": "obj_0001",
|
||||
"type": "interactable",
|
||||
"asset_id": "props/chest",
|
||||
"transform": { "pos": [400.0, -110.0, 0.0],
|
||||
"rot": [0.0, 0.0, 0.0, 1.0],
|
||||
"scale": [1.0, 1.0, 1.0] },
|
||||
"properties": { "loot_table": "chest_basic", "locked": false },
|
||||
"dynamic": false,
|
||||
"flags": { "categories": { "violence": "none" }, "mature": false, "sources": [] }
|
||||
}
|
||||
],
|
||||
"flags": { "categories": { "violence": "none" }, "mature": false, "sources": [] },
|
||||
"meta": { "created_at": "2026-08-17T00:00:00Z",
|
||||
"updated_at": "2026-08-17T00:00:00Z",
|
||||
"revision": 3,
|
||||
"author": "agent-bot" },
|
||||
"checksum": "9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08"
|
||||
}
|
||||
```
|
||||
|
||||
### 3.6 Binary Encoding
|
||||
|
||||
The binary encoding is the **runtime and network** representation. It is compact
|
||||
and byte-stable. It uses a simple, explicitly-specified layout (no external
|
||||
serialization library) so it can be produced and consumed identically by the
|
||||
Godot client (GDScript) and the Python backend.
|
||||
|
||||
#### 3.6.1 Header
|
||||
|
||||
| Offset | Size | Field | Type / Encoding |
|
||||
|--------|------|--------------|------------------------------------------|
|
||||
| 0 | 4 | magic | ASCII `"AGPC"` (0x41 0x47 0x50 0x43) |
|
||||
| 4 | 2 | version | `uint16` LE (currently `1`) |
|
||||
| 6 | 2 | header_len | `uint16` LE (bytes of header after this) |
|
||||
| 8 | 4 | flags | `uint32` LE (bitmask, reserved) |
|
||||
| 12 | 4 | payload_len | `uint32` LE (bytes of payload body) |
|
||||
| 16 | 32 | checksum | SHA-256 of payload body (hex, 32 bytes) |
|
||||
|
||||
Total header size: **48 bytes**.
|
||||
|
||||
#### 3.6.2 Payload Body
|
||||
|
||||
The payload body is a sequence of typed sections. Each section has a small
|
||||
header:
|
||||
|
||||
| Offset | Size | Field | Type / Encoding |
|
||||
|--------|------|------------|----------------------------|
|
||||
| 0 | 1 | section_id | `uint8` (see table below) |
|
||||
| 1 | 4 | section_len| `uint32` LE (bytes of section data) |
|
||||
| 5 | ... | data | section-specific |
|
||||
|
||||
Section IDs:
|
||||
|
||||
| section_id | Section | Data layout |
|
||||
|------------|----------------|-------------------------------------------------------------------|
|
||||
| `0x01` | metadata | world_id, room_id (length-prefixed strings), coord (3×int32), bounds (6×float32) |
|
||||
| `0x02` | tile layer | name, layer_id, dims (3×uint16), palette, dense tile indices |
|
||||
| `0x03` | object | one `WorldObject` (repeated; one section per object) |
|
||||
| `0x04` | content flags | category severities (8×uint8), mature (uint8), sources (string list) |
|
||||
| `0x05` | meta | created_at, updated_at (int64 unix), revision (uint32), author (string) |
|
||||
|
||||
**String encoding:** length-prefixed UTF-8 — `uint16` LE byte length followed by
|
||||
the UTF-8 bytes.
|
||||
|
||||
**Tile layer data layout (section `0x02`):**
|
||||
|
||||
```
|
||||
name : string
|
||||
layer_id : uint16 LE
|
||||
width : uint16 LE
|
||||
height : uint16 LE
|
||||
depth : uint16 LE
|
||||
palette_count : uint16 LE
|
||||
palette : palette_count × TileDef
|
||||
tile_count : uint32 LE
|
||||
tiles : tile_count × uint16 LE (dense, row-major)
|
||||
```
|
||||
|
||||
```
|
||||
TileDef:
|
||||
id : uint16 LE
|
||||
asset_id : string
|
||||
solid : uint8
|
||||
flags : uint32 LE
|
||||
variants : uint8
|
||||
```
|
||||
|
||||
**Object data layout (section `0x03`):**
|
||||
|
||||
```
|
||||
id : string
|
||||
type : string
|
||||
asset_id : string
|
||||
pos : 3 × float32
|
||||
rot : 4 × float32
|
||||
scale : 3 × float32
|
||||
dynamic : uint8
|
||||
properties : JSON string (length-prefixed)
|
||||
flags : ContentFlags (see 0x04 layout)
|
||||
```
|
||||
|
||||
**Content flags layout (section `0x04`):**
|
||||
|
||||
```
|
||||
violence, sexual, language, substance, gambling, horror, hate, custom
|
||||
: 8 × uint8 (severity enum: 0=none,1=mild,2=moderate,3=severe)
|
||||
mature : uint8
|
||||
source_count: uint16 LE
|
||||
sources : source_count × string
|
||||
```
|
||||
|
||||
#### 3.6.3 Byte-Stability
|
||||
|
||||
For a given logical payload, the binary encoding is **deterministic**:
|
||||
|
||||
- All integers are little-endian.
|
||||
- All strings are UTF-8, length-prefixed, and never null-terminated.
|
||||
- Maps (e.g. `properties`) are serialized as a **canonical JSON string** with
|
||||
keys sorted lexicographically.
|
||||
- The `checksum` is the SHA-256 of the payload body bytes.
|
||||
|
||||
This guarantees that two encoders produce identical bytes, enabling content
|
||||
addressing, caching, and reproducible tests.
|
||||
|
||||
---
|
||||
|
||||
## 4. SQLite Persistence Schema
|
||||
|
||||
The server persists world state in a **SQLite** database. SQLite is chosen for
|
||||
its zero-configuration, single-file, transactional, and embedded nature — ideal
|
||||
for a server that owns the world store and needs ACID guarantees without a
|
||||
separate database process.
|
||||
|
||||
### 4.1 Database Layout
|
||||
|
||||
The database file is `world.db` (path configurable). It contains the following
|
||||
tables:
|
||||
|
||||
```
|
||||
worlds
|
||||
rooms
|
||||
chunks
|
||||
chunk_objects
|
||||
content_flags
|
||||
revisions
|
||||
```
|
||||
|
||||
### 4.2 `worlds`
|
||||
|
||||
Top-level world containers.
|
||||
|
||||
```sql
|
||||
CREATE TABLE worlds (
|
||||
id TEXT PRIMARY KEY, -- e.g. 'w_0001'
|
||||
name TEXT NOT NULL,
|
||||
description TEXT,
|
||||
chunk_size_x INTEGER NOT NULL DEFAULT 32,
|
||||
chunk_size_y INTEGER NOT NULL DEFAULT 32,
|
||||
chunk_size_z INTEGER NOT NULL DEFAULT 1,
|
||||
origin_x REAL NOT NULL DEFAULT 0,
|
||||
origin_y REAL NOT NULL DEFAULT 0,
|
||||
origin_z REAL NOT NULL DEFAULT 0,
|
||||
created_at TEXT NOT NULL, -- ISO-8601 UTC
|
||||
updated_at TEXT NOT NULL
|
||||
);
|
||||
```
|
||||
|
||||
### 4.3 `rooms`
|
||||
|
||||
Rooms within a world.
|
||||
|
||||
```sql
|
||||
CREATE TABLE rooms (
|
||||
id TEXT PRIMARY KEY, -- e.g. 'r_0001'
|
||||
world_id TEXT NOT NULL REFERENCES worlds(id) ON DELETE CASCADE,
|
||||
name TEXT NOT NULL,
|
||||
bounds_min_x REAL NOT NULL,
|
||||
bounds_min_y REAL NOT NULL,
|
||||
bounds_min_z REAL NOT NULL DEFAULT 0,
|
||||
bounds_max_x REAL NOT NULL,
|
||||
bounds_max_y REAL NOT NULL,
|
||||
bounds_max_z REAL NOT NULL DEFAULT 1,
|
||||
created_at TEXT NOT NULL,
|
||||
updated_at TEXT NOT NULL,
|
||||
UNIQUE (world_id, name)
|
||||
);
|
||||
CREATE INDEX idx_rooms_world ON rooms(world_id);
|
||||
```
|
||||
|
||||
### 4.4 `chunks`
|
||||
|
||||
The core persistence table. One row per chunk. The **payload** is stored as a
|
||||
BLOB in the **binary format** (§3.6); the JSON form is derived on demand for
|
||||
authoring/debugging and is not stored (to avoid dual-write drift).
|
||||
|
||||
```sql
|
||||
CREATE TABLE chunks (
|
||||
key TEXT PRIMARY KEY, -- canonical key 'world:room:cx:cy:cz'
|
||||
world_id TEXT NOT NULL REFERENCES worlds(id) ON DELETE CASCADE,
|
||||
room_id TEXT NOT NULL REFERENCES rooms(id) ON DELETE CASCADE,
|
||||
cx INTEGER NOT NULL,
|
||||
cy INTEGER NOT NULL,
|
||||
cz INTEGER NOT NULL DEFAULT 0,
|
||||
format_version INTEGER NOT NULL DEFAULT 1,
|
||||
payload BLOB NOT NULL, -- binary chunk encoding (§3.6)
|
||||
payload_len INTEGER NOT NULL,
|
||||
checksum TEXT NOT NULL, -- SHA-256 of payload
|
||||
revision INTEGER NOT NULL DEFAULT 0,
|
||||
dirty INTEGER NOT NULL DEFAULT 0, -- 1 = needs flush to disk
|
||||
created_at TEXT NOT NULL,
|
||||
updated_at TEXT NOT NULL,
|
||||
UNIQUE (world_id, room_id, cx, cy, cz)
|
||||
);
|
||||
CREATE INDEX idx_chunks_world_room ON chunks(world_id, room_id);
|
||||
CREATE INDEX idx_chunks_coord ON chunks(cx, cy, cz);
|
||||
```
|
||||
|
||||
**Design notes:**
|
||||
|
||||
- The `payload` BLOB is the single source of truth for chunk content. The
|
||||
`checksum` guards against corruption and enables content addressing.
|
||||
- `revision` increments on every write; it is used for optimistic concurrency
|
||||
and change detection (see §5.4).
|
||||
- `dirty` marks chunks that have been modified in memory but not yet flushed,
|
||||
enabling a write-behind persistence strategy (see §5.5).
|
||||
|
||||
### 4.5 `chunk_objects`
|
||||
|
||||
A denormalized, queryable index of the objects inside each chunk. This is
|
||||
**derived** from the chunk payload and kept in sync by the write path. It exists
|
||||
so the server can answer queries like "which chunks contain a door?" without
|
||||
parsing every payload BLOB.
|
||||
|
||||
```sql
|
||||
CREATE TABLE chunk_objects (
|
||||
id TEXT NOT NULL, -- object id (unique within chunk)
|
||||
chunk_key TEXT NOT NULL REFERENCES chunks(key) ON DELETE CASCADE,
|
||||
type TEXT NOT NULL, -- 'prop', 'interactable', ...
|
||||
asset_id TEXT,
|
||||
dynamic INTEGER NOT NULL DEFAULT 0,
|
||||
pos_x REAL NOT NULL,
|
||||
pos_y REAL NOT NULL,
|
||||
pos_z REAL NOT NULL DEFAULT 0,
|
||||
PRIMARY KEY (chunk_key, id)
|
||||
);
|
||||
CREATE INDEX idx_chunk_objects_type ON chunk_objects(type);
|
||||
CREATE INDEX idx_chunk_objects_asset ON chunk_objects(asset_id);
|
||||
```
|
||||
|
||||
### 4.6 `content_flags`
|
||||
|
||||
Persists the aggregated moderation flags per chunk (and optionally per object).
|
||||
This lets the server enforce age/content gates at load time without parsing
|
||||
payloads.
|
||||
|
||||
```sql
|
||||
CREATE TABLE content_flags (
|
||||
chunk_key TEXT NOT NULL REFERENCES chunks(key) ON DELETE CASCADE,
|
||||
object_id TEXT, -- NULL = chunk-level flag
|
||||
violence INTEGER NOT NULL DEFAULT 0,
|
||||
sexual INTEGER NOT NULL DEFAULT 0,
|
||||
language INTEGER NOT NULL DEFAULT 0,
|
||||
substance INTEGER NOT NULL DEFAULT 0,
|
||||
gambling INTEGER NOT NULL DEFAULT 0,
|
||||
horror INTEGER NOT NULL DEFAULT 0,
|
||||
hate INTEGER NOT NULL DEFAULT 0,
|
||||
custom INTEGER NOT NULL DEFAULT 0,
|
||||
mature INTEGER NOT NULL DEFAULT 0,
|
||||
sources TEXT NOT NULL DEFAULT '[]', -- JSON array of flag ids
|
||||
PRIMARY KEY (chunk_key, object_id)
|
||||
);
|
||||
CREATE INDEX idx_content_flags_mature ON content_flags(mature);
|
||||
```
|
||||
|
||||
Severity is stored as `0=none, 1=mild, 2=moderate, 3=severe`.
|
||||
|
||||
### 4.7 `revisions`
|
||||
|
||||
An append-only audit log of chunk writes. Enables rollback, auditing, and
|
||||
replication of changes.
|
||||
|
||||
```sql
|
||||
CREATE TABLE revisions (
|
||||
id INTEGER PRIMARY KEY AUTOINCREMENT,
|
||||
chunk_key TEXT NOT NULL REFERENCES chunks(key) ON DELETE CASCADE,
|
||||
revision INTEGER NOT NULL,
|
||||
actor TEXT NOT NULL, -- user / agent id
|
||||
action TEXT NOT NULL, -- 'create' | 'update' | 'delete'
|
||||
checksum TEXT NOT NULL,
|
||||
created_at TEXT NOT NULL
|
||||
);
|
||||
CREATE INDEX idx_revisions_chunk ON revisions(chunk_key);
|
||||
```
|
||||
|
||||
### 4.8 Schema Versioning & Migrations
|
||||
|
||||
The database carries a schema version in a `meta` table:
|
||||
|
||||
```sql
|
||||
CREATE TABLE meta (
|
||||
key TEXT PRIMARY KEY,
|
||||
value TEXT NOT NULL
|
||||
);
|
||||
-- seed: INSERT INTO meta(key, value) VALUES ('schema_version', '1');
|
||||
```
|
||||
|
||||
Migrations are applied in order at startup. Each migration is a numbered SQL
|
||||
script; the server tracks the applied version in `meta` and applies any pending
|
||||
migrations transactionally. This keeps the schema forward-compatible as the
|
||||
chunk format evolves.
|
||||
|
||||
---
|
||||
|
||||
## 5. Read/Write API
|
||||
|
||||
The API is exposed as a **Python service layer** on the backend (the same
|
||||
process that owns the SQLite store) and consumed by the Godot client over the
|
||||
network transport (see `networking.md`). The service layer is the **only**
|
||||
writer to the database; clients never touch SQLite directly.
|
||||
|
||||
### 5.1 Service Interface (Python)
|
||||
|
||||
```python
|
||||
class WorldStore:
|
||||
"""Owns the SQLite connection and chunk read/write operations."""
|
||||
|
||||
def get_chunk(self, key: str) -> Chunk | None: ...
|
||||
def get_chunk_binary(self, key: str) -> bytes | None: ...
|
||||
def put_chunk(self, chunk: Chunk, actor: str) -> Chunk: ...
|
||||
def delete_chunk(self, key: str, actor: str) -> None: ...
|
||||
def list_chunks(self, world_id: str, room_id: str | None = None,
|
||||
bounds: Bounds | None = None) -> list[str]: ...
|
||||
def get_chunk_flags(self, key: str) -> ContentFlags: ...
|
||||
def flush_dirty(self) -> int: ...
|
||||
def migrate(self) -> None: ...
|
||||
```
|
||||
|
||||
### 5.2 Encoding Helpers
|
||||
|
||||
The service layer provides symmetric encode/decode functions shared by the
|
||||
client and server:
|
||||
|
||||
```python
|
||||
def encode_binary(chunk: Chunk) -> bytes: ...
|
||||
def decode_binary(data: bytes) -> Chunk: ...
|
||||
def encode_json(chunk: Chunk) -> str: ...
|
||||
def decode_json(text: str) -> Chunk: ...
|
||||
def checksum(payload: bytes) -> str: ...
|
||||
```
|
||||
|
||||
These are the single implementation of the format spec (§3), so the Godot
|
||||
client and Python backend never drift.
|
||||
|
||||
### 5.3 Network RPCs
|
||||
|
||||
The chunk API is exposed to the client via RPCs (matching the networking
|
||||
architecture). All chunk traffic is **reliable** (chunks are discrete,
|
||||
must-arrive data).
|
||||
|
||||
| RPC | Direction | Payload | Notes |
|
||||
|----------------------------|-----------|-------------------------------------------|-------|
|
||||
| `request_chunk` | C → S | `{ key }` | Client asks for a chunk |
|
||||
| `chunk_data` | S → C | `{ key, binary_payload, checksum }` | Server streams a chunk |
|
||||
| `request_chunk_edit` | C → S | `{ key, base_revision, delta }` | Client submits an edit |
|
||||
| `chunk_edit_result` | S → C | `{ key, success, new_revision, error? }` | Acknowledges an edit |
|
||||
| `chunk_invalidated` | S → C | `{ key, new_revision }` | Server pushes a change |
|
||||
| `request_chunk_flags` | C → S | `{ key }` | Age/content gate check |
|
||||
|
||||
### 5.4 Edit & Concurrency Model
|
||||
|
||||
- **Read:** Client requests a chunk; server returns the binary payload and its
|
||||
`revision`.
|
||||
- **Edit:** Client submits a **delta** against a known `base_revision`. The
|
||||
server applies the delta, increments `revision`, persists, and returns the new
|
||||
revision.
|
||||
- **Optimistic concurrency:** If the chunk's current revision differs from the
|
||||
client's `base_revision`, the server rejects the edit with a conflict error
|
||||
and the client re-fetches and re-applies. This prevents lost updates when two
|
||||
clients edit the same chunk.
|
||||
- **Deltas:** A delta is a JSON patch (RFC 6902 style) applied to the chunk's
|
||||
logical model. The server validates the patched chunk (schema, bounds,
|
||||
moderation) before persisting.
|
||||
|
||||
### 5.5 Write-Behind Persistence
|
||||
|
||||
To amortize disk I/O, the server keeps a **dirty set** of chunks modified in
|
||||
memory and flushes them to SQLite in batches:
|
||||
|
||||
1. `put_chunk` updates the in-memory chunk and marks it `dirty`.
|
||||
2. A background flusher periodically calls `flush_dirty()`, which writes all
|
||||
dirty chunks in a single transaction and clears the `dirty` flag.
|
||||
3. On graceful shutdown, `flush_dirty()` is called to ensure durability.
|
||||
|
||||
This keeps the hot path (in-memory chunk access) fast while guaranteeing
|
||||
durability at shutdown and on a configurable interval.
|
||||
|
||||
### 5.6 Streaming & Caching
|
||||
|
||||
- The server streams only the chunks a client needs (those within the client's
|
||||
view radius), using `list_chunks` with a bounds query.
|
||||
- Chunks are cached in memory (LRU) keyed by `key`; the cache is invalidated on
|
||||
write.
|
||||
- The binary payload is content-addressed by `checksum`, so unchanged chunks can
|
||||
be served from cache without re-reading SQLite.
|
||||
|
||||
---
|
||||
|
||||
## 6. Format Versioning & Migration
|
||||
|
||||
- The chunk format `version` field (currently `1`) is checked on decode. A
|
||||
decoder that encounters a higher version than it supports **rejects** the
|
||||
chunk with a clear error rather than misreading it.
|
||||
- The SQLite `schema_version` in `meta` drives database migrations (§4.8).
|
||||
- Chunk payloads are migrated **lazily**: when a chunk is read and its
|
||||
`format_version` is older than the current one, the server migrates it to the
|
||||
current version in memory and marks it dirty so it is rewritten on the next
|
||||
flush. This avoids a costly full-world migration at startup.
|
||||
|
||||
---
|
||||
|
||||
## 7. Security & Integrity
|
||||
|
||||
- **Server-authoritative writes:** Only the `WorldStore` writes to SQLite;
|
||||
clients submit deltas that are validated before application.
|
||||
- **Checksum verification:** Every chunk payload is checksummed (SHA-256) on
|
||||
write and verified on read. Corruption is detected and the chunk is re-fetched
|
||||
or flagged.
|
||||
- **Bounds validation:** Chunk coordinates and object positions are validated
|
||||
against the world's chunk dimensions and room bounds before persistence.
|
||||
- **Moderation enforcement:** `content_flags` are checked at load time; mature
|
||||
chunks are gated behind the age-verification flow (see `content_moderation.md`).
|
||||
- **Input validation:** All string fields are length-limited and validated
|
||||
against allowed character sets to prevent injection and oversized payloads.
|
||||
|
||||
---
|
||||
|
||||
## 8. Open Questions / Future Work
|
||||
|
||||
- **Volumetric worlds:** The schema and format already support `CHUNK_SIZE_Z >
|
||||
1`, but the tooling and streaming for 3D chunks are not yet specified.
|
||||
- **Chunk compression:** For very large worlds, the binary payload could be
|
||||
compressed (e.g. zstd) before storage/transfer. The header reserves a `flags`
|
||||
bitmask for a compression flag.
|
||||
- **Multi-server sharding:** If a single SQLite file becomes a bottleneck, the
|
||||
`chunks` table could be sharded by `world_id` across multiple databases. The
|
||||
key design already supports this (world_id is a leading key component).
|
||||
- **Delta compression for streaming:** Instead of sending full chunks, the
|
||||
server could send only the delta between revisions to reduce bandwidth for
|
||||
frequently-updated chunks.
|
||||
Reference in New Issue
Block a user