WIP checkpoint: Friends/follow/block models + Alembic migration

backend/alembic/env.py

@@ -8,7 +8,7 @@ from sqlalchemy.ext.asyncio import create_async_engine
 
 from app.config import settings
 from app.database import Base
-from app.models import user, session, world, asset  # noqa: F401
+from app.models import user, session, world, asset, friendship, follow, block  # noqa: F401
 
 # this is the Alembic Config object, which provides
 # access to the values within the .ini file in use.

backend/alembic/versions/0002_social_graph.py

@@ -0,0 +1,136 @@
+"""social graph: friendships, follows, blocks
+
+Revision ID: 0002_social_graph
+Revises: 0001_initial
+Create Date: 2026-08-18 00:00:00.000000
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+# revision identifiers, used by Alembic.
+revision: str = "0002_social_graph"
+down_revision: Union[str, None] = "0001_initial"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    """Create friendships, follows, and blocks tables."""
+    op.create_table(
+        "friendships",
+        sa.Column("id", sa.Integer(), nullable=False),
+        sa.Column("requester_id", sa.Integer(), nullable=False),
+        sa.Column("addressee_id", sa.Integer(), nullable=False),
+        sa.Column("status", sa.String(length=20), server_default="pending", nullable=False),
+        sa.Column("created_at", sa.DateTime(timezone=True), server_default=sa.func.now(), nullable=False),
+        sa.Column("updated_at", sa.DateTime(timezone=True), nullable=True),
+        sa.CheckConstraint(
+            "status IN ('pending', 'accepted')",
+            name="ck_friendships_status",
+        ),
+        sa.CheckConstraint(
+            "requester_id <> addressee_id",
+            name="ck_friendships_no_self",
+        ),
+        sa.ForeignKeyConstraint(
+            ["addressee_id"],
+            ["users.id"],
+            ondelete="CASCADE",
+        ),
+        sa.ForeignKeyConstraint(
+            ["requester_id"],
+            ["users.id"],
+            ondelete="CASCADE",
+        ),
+        sa.PrimaryKeyConstraint("id"),
+        sa.UniqueConstraint(
+            "requester_id",
+            "addressee_id",
+            name="uq_friendships_requester_addressee",
+        ),
+    )
+    op.create_index(op.f("ix_friendships_id"), "friendships", ["id"], unique=False)
+    op.create_index(op.f("ix_friendships_addressee_id"), "friendships", ["addressee_id"], unique=False)
+    op.create_index(op.f("ix_friendships_requester_id"), "friendships", ["requester_id"], unique=False)
+
+    op.create_table(
+        "follows",
+        sa.Column("id", sa.Integer(), nullable=False),
+        sa.Column("follower_id", sa.Integer(), nullable=False),
+        sa.Column("followed_id", sa.Integer(), nullable=False),
+        sa.Column("created_at", sa.DateTime(timezone=True), server_default=sa.func.now(), nullable=False),
+        sa.CheckConstraint(
+            "follower_id <> followed_id",
+            name="ck_follows_no_self",
+        ),
+        sa.ForeignKeyConstraint(
+            ["followed_id"],
+            ["users.id"],
+            ondelete="CASCADE",
+        ),
+        sa.ForeignKeyConstraint(
+            ["follower_id"],
+            ["users.id"],
+            ondelete="CASCADE",
+        ),
+        sa.PrimaryKeyConstraint("id"),
+        sa.UniqueConstraint(
+            "follower_id",
+            "followed_id",
+            name="uq_follows_follower_followed",
+        ),
+    )
+    op.create_index(op.f("ix_follows_id"), "follows", ["id"], unique=False)
+    op.create_index(op.f("ix_follows_followed_id"), "follows", ["followed_id"], unique=False)
+    op.create_index(op.f("ix_follows_follower_id"), "follows", ["follower_id"], unique=False)
+
+    op.create_table(
+        "blocks",
+        sa.Column("id", sa.Integer(), nullable=False),
+        sa.Column("blocker_id", sa.Integer(), nullable=False),
+        sa.Column("blocked_id", sa.Integer(), nullable=False),
+        sa.Column("created_at", sa.DateTime(timezone=True), server_default=sa.func.now(), nullable=False),
+        sa.CheckConstraint(
+            "blocker_id <> blocked_id",
+            name="ck_blocks_no_self",
+        ),
+        sa.ForeignKeyConstraint(
+            ["blocked_id"],
+            ["users.id"],
+            ondelete="CASCADE",
+        ),
+        sa.ForeignKeyConstraint(
+            ["blocker_id"],
+            ["users.id"],
+            ondelete="CASCADE",
+        ),
+        sa.PrimaryKeyConstraint("id"),
+        sa.UniqueConstraint(
+            "blocker_id",
+            "blocked_id",
+            name="uq_blocks_blocker_blocked",
+        ),
+    )
+    op.create_index(op.f("ix_blocks_id"), "blocks", ["id"], unique=False)
+    op.create_index(op.f("ix_blocks_blocked_id"), "blocks", ["blocked_id"], unique=False)
+    op.create_index(op.f("ix_blocks_blocker_id"), "blocks", ["blocker_id"], unique=False)
+
+
+def downgrade() -> None:
+    """Drop friendships, follows, and blocks tables."""
+    op.drop_index(op.f("ix_blocks_blocker_id"), table_name="blocks")
+    op.drop_index(op.f("ix_blocks_blocked_id"), table_name="blocks")
+    op.drop_index(op.f("ix_blocks_id"), table_name="blocks")
+    op.drop_table("blocks")
+
+    op.drop_index(op.f("ix_follows_follower_id"), table_name="follows")
+    op.drop_index(op.f("ix_follows_followed_id"), table_name="follows")
+    op.drop_index(op.f("ix_follows_id"), table_name="follows")
+    op.drop_table("follows")
+
+    op.drop_index(op.f("ix_friendships_requester_id"), table_name="friendships")
+    op.drop_index(op.f("ix_friendships_addressee_id"), table_name="friendships")
+    op.drop_index(op.f("ix_friendships_id"), table_name="friendships")
+    op.drop_table("friendships")

backend/app/models/__init__.py

@@ -2,5 +2,17 @@ from app.models.user import User
 from app.models.session import Session
 from app.models.world import World
 from app.models.asset import Asset
+from app.models.friendship import Friendship, FriendshipStatus
+from app.models.follow import Follow
+from app.models.block import Block
 
-__all__ = ["User", "Session", "World", "Asset"]
+__all__ = [
+    "User",
+    "Session",
+    "World",
+    "Asset",
+    "Friendship",
+    "FriendshipStatus",
+    "Follow",
+    "Block",
+]

backend/app/models/block.py

@@ -0,0 +1,48 @@
+"""Block model: a hard deny that also hides content and prevents DMs."""
+
+from sqlalchemy import CheckConstraint, Column, DateTime, ForeignKey, Integer, UniqueConstraint
+from sqlalchemy.orm import relationship
+from sqlalchemy.sql import func
+
+from app.database import Base
+
+
+class Block(Base):
+    __tablename__ = "blocks"
+    __table_args__ = (
+        UniqueConstraint(
+            "blocker_id",
+            "blocked_id",
+            name="uq_blocks_pair",
+        ),
+        CheckConstraint(
+            "blocker_id <> blocked_id",
+            name="ck_blocks_no_self",
+        ),
+    )
+
+    id = Column(Integer, primary_key=True, index=True)
+    blocker_id = Column(
+        Integer,
+        ForeignKey("users.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    blocked_id = Column(
+        Integer,
+        ForeignKey("users.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+
+    blocker = relationship(
+        "User",
+        foreign_keys=[blocker_id],
+        back_populates="blocks_issued",
+    )
+    blocked = relationship(
+        "User",
+        foreign_keys=[blocked_id],
+        back_populates="blocks_received",
+    )

backend/app/models/follow.py

@@ -0,0 +1,48 @@
+"""Follow model: a one-way relationship requiring no approval."""
+
+from sqlalchemy import CheckConstraint, Column, DateTime, ForeignKey, Integer, UniqueConstraint
+from sqlalchemy.orm import relationship
+from sqlalchemy.sql import func
+
+from app.database import Base
+
+
+class Follow(Base):
+    __tablename__ = "follows"
+    __table_args__ = (
+        UniqueConstraint(
+            "follower_id",
+            "followed_id",
+            name="uq_follows_pair",
+        ),
+        CheckConstraint(
+            "follower_id <> followed_id",
+            name="ck_follows_no_self",
+        ),
+    )
+
+    id = Column(Integer, primary_key=True, index=True)
+    follower_id = Column(
+        Integer,
+        ForeignKey("users.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    followed_id = Column(
+        Integer,
+        ForeignKey("users.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+
+    follower = relationship(
+        "User",
+        foreign_keys=[follower_id],
+        back_populates="following",
+    )
+    followed = relationship(
+        "User",
+        foreign_keys=[followed_id],
+        back_populates="followers",
+    )

backend/app/models/friendship.py

@@ -0,0 +1,74 @@
+"""Friendship model: a one-directional request that becomes mutual on accept."""
+
+from sqlalchemy import (
+    CheckConstraint,
+    Column,
+    DateTime,
+    ForeignKey,
+    Integer,
+    String,
+    UniqueConstraint,
+)
+from sqlalchemy.orm import relationship
+from sqlalchemy.sql import func
+
+from app.database import Base
+
+
+class FriendshipStatus:
+    """String values for the friendship.status column."""
+
+    PENDING = "pending"
+    ACCEPTED = "accepted"
+
+
+class Friendship(Base):
+    __tablename__ = "friendships"
+    __table_args__ = (
+        UniqueConstraint(
+            "requester_id",
+            "addressee_id",
+            name="uq_friendships_pair",
+        ),
+        CheckConstraint(
+            "requester_id <> addressee_id",
+            name="ck_friendships_no_self",
+        ),
+        CheckConstraint(
+            "status IN ('pending', 'accepted')",
+            name="ck_friendships_status",
+        ),
+    )
+
+    id = Column(Integer, primary_key=True, index=True)
+    requester_id = Column(
+        Integer,
+        ForeignKey("users.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    addressee_id = Column(
+        Integer,
+        ForeignKey("users.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    status = Column(
+        String(20),
+        nullable=False,
+        default=FriendshipStatus.PENDING,
+        server_default=FriendshipStatus.PENDING,
+    )
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+    updated_at = Column(DateTime(timezone=True), onupdate=func.now())
+
+    requester = relationship(
+        "User",
+        foreign_keys=[requester_id],
+        back_populates="sent_friend_requests",
+    )
+    addressee = relationship(
+        "User",
+        foreign_keys=[addressee_id],
+        back_populates="received_friend_requests",
+    )

backend/app/models/user.py

@@ -19,3 +19,41 @@ class User(Base):
     sessions = relationship("Session", back_populates="user", cascade="all, delete-orphan")
     worlds = relationship("World", back_populates="owner")
     assets = relationship("Asset", back_populates="owner")
+
+    # Social graph
+    sent_friend_requests = relationship(
+        "Friendship",
+        foreign_keys="Friendship.requester_id",
+        back_populates="requester",
+        cascade="all, delete-orphan",
+    )
+    received_friend_requests = relationship(
+        "Friendship",
+        foreign_keys="Friendship.addressee_id",
+        back_populates="addressee",
+        cascade="all, delete-orphan",
+    )
+    following = relationship(
+        "Follow",
+        foreign_keys="Follow.follower_id",
+        back_populates="follower",
+        cascade="all, delete-orphan",
+    )
+    followers = relationship(
+        "Follow",
+        foreign_keys="Follow.followed_id",
+        back_populates="followed",
+        cascade="all, delete-orphan",
+    )
+    blocks_issued = relationship(
+        "Block",
+        foreign_keys="Block.blocker_id",
+        back_populates="blocker",
+        cascade="all, delete-orphan",
+    )
+    blocks_received = relationship(
+        "Block",
+        foreign_keys="Block.blocked_id",
+        back_populates="blocked",
+        cascade="all, delete-orphan",
+    )

docs/planning/economy.md

@@ -1,295 +0,0 @@
-# Economy — Currency, Marketplace & Creator Payouts — Plan
-
-> **Status:** Planned
-> **Owner:** Platform team
-> **Feature ID:** `economy`
-> **Godot version:** 4.6.2 stable
-> **Backend:** FastAPI + SQLAlchemy (async) + PostgreSQL + Redis
-
-## 1. Overview
-
-This document breaks the **Economy** feature into user stories and right-sized
-implementation tasks. The feature delivers:
-
-- **Virtual currency ("Credits")** — a single, server-authoritative currency
-  with an immutable, append-only transaction ledger.
-- **Premium purchase** — buying Credits with real money through a pluggable
-  payment-provider hook.
-- **Marketplace** — user-generated content (UGC) listings where creators sell
-  items (assets, avatar items, experience passes) to players for Credits.
-- **Creator payouts** — accumulating creator earnings and paying them out to
-  external accounts through a pluggable payout-provider hook.
-- **Godot client** — wallet/transaction history, marketplace browse/buy/sell,
-  and creator payout screens.
-
-The economy is the monetization backbone of the platform. Because it moves
-virtual value between real people, correctness (no double-spend, no lost funds,
-no balance drift) and safety (fraud prevention, moderation, audit) are treated
-as **blocking requirements**, not add-ons.
-
-## 2. Why correctness is the differentiator
-
-The platform is a creator economy (players buy UGC from other players). The
-economy is the highest-risk surface after chat: a single arithmetic or
-concurrency bug can mint or destroy value and irreversibly erode trust.
-Correctness is therefore designed in from the start:
-
-- **One currency, integer units.** Credits are whole-number integers. There are
-  no floats, no rounding, and no client-computed totals.
-- **Append-only ledger.** Every balance change is a row in a `transactions`
-  table with a signed amount, a `balance_after` snapshot, a reference to the
-  event that caused it, and an **idempotency key** so retries cannot double
-  credit or double debit.
-- **Atomic, locked mutations.** Balance changes run in a single database
-  transaction with row locking (`SELECT ... FOR UPDATE`) so concurrent
-  purchases/payouts cannot race.
-- **Escrow hold.** Marketplace proceeds are held in `pending_escrow` for a
-  configurable window before becoming available to the seller, so fraudulent
-  or moderated sales can be reversed without clawing back paid-out funds.
-- **Server-authoritative fees.** The platform commission is computed
-  server-side from a configured rate; the client never supplies the fee or the
-  seller's net.
-
-## 3. Existing constraints (do not re-build)
-
-- **Auth:** JWT bearer tokens; `get_current_user` / `CurrentUser` dependency in
-  `app/dependencies.py`. All economy endpoints reuse this.
-- **DB:** async SQLAlchemy + Alembic; migration `0001_initial` is the head.
-  Existing tables: `users`, `sessions`, `worlds`, `assets`.
-- **Redis:** configured (`REDIS_URL`) but unused so far; adopted here for
-  idempotency short-caching and rate limiting.
-- **Models:** `User` (owner_id), `Asset` (owner_id, is_public, asset_type).
-  Marketplace items reference existing `assets` rows and/or avatar items.
-- **Content moderation:** `docs/architecture/content_moderation.md` defines
-  flag vocabulary, age gate, and moderation actions. Marketplace items and
-  listings must inherit and enforce these rules (see §7).
-- **Client:** Godot 4.6.2, minimal `main_menu.gd`; no economy UI yet.
-
-## 4. Key design decisions
-
-| Concern | Decision |
-|---|---|
-| Currency model | Single virtual currency **"Credits" (CR)**, integer units. One wallet row per user; no fractional amounts. |
-| Ledger | Append-only `transactions` table: signed `amount`, `balance_after`, `reference_type`/`reference_id`, unique `idempotency_key`. |
-| Concurrency | `SELECT ... FOR UPDATE` on the wallet row inside the mutation transaction; never read-modify-write from stale data. |
-| Payments | Pluggable `PaymentProvider` interface with a **no-op default** that simulates a confirmed payment for dev/testing (clearly flagged). Stripe/PayPal later. |
-| Marketplace items | `catalog_items` (what is sold) + `marketplace_listings` (a seller's offer with a price/status). One item can have multiple listings over time. |
-| Purchase flow | Atomic transaction: debit buyer → hold funds in escrow (`pending_escrow`) → grant item. Platform fee computed server-side. |
-| Escrow | Configurable hold window (default 72h) before `pending_escrow` becomes available seller earnings. Refunds during the window reverse the sale. |
-| Fees | Single configurable `MARKETPLACE_FEE_RATE` (default `0.30`). `seller_net = floor(price * (1 - fee_rate))`. |
-| Creator balance | `creator_balances` table: `available` (earned, payable), `pending` (inside an open payout request), `lifetime_earned`. Updated in the same transaction as the sale completion. |
-| Payouts | Pluggable `PayoutProvider.pay()` with a no-op default (simulated external ref). Minimum payout threshold, admin review for large payouts. |
-| Idempotency | Every money-moving request carries a client-generated `Idempotency-Key`; duplicate keys return the original result. |
-| Rate limiting | Redis token-bucket dependency reused from the social feature for purchase/listing/payout endpoints. |
-| Moderation | Listings enforce content flags + age gate; moderators can `delist`/`remove`; fraud/chargeback reversal is an audited admin action. |
-
-## 5. User stories
-
-### US-1 Currency & wallet
-As a player, I can see my Credit balance and transaction history, and the system
-credits/debits my wallet only through server-authoritative events.
-
-**Acceptance criteria**
-- Exactly one wallet per user, created lazily on first use.
-- Balance is always a non-negative integer; no operation can make it negative.
-- Every mutation appends an immutable ledger row with amount, resulting balance,
-  reference, and idempotency key.
-- Retrying a request with the same idempotency key does not double-apply.
-- `GET` endpoints expose current balance and paged transaction history.
-
-### US-2 Premium purchase (buy Credits)
-As a player, I can purchase Credits with real money and have them credited only
-after the payment is confirmed.
-
-**Acceptance criteria**
-- A purchase session is created through the payment provider (or the no-op
-  default) and is idempotent.
-- Credits are granted exactly once, only after a verified provider confirmation
-  (webhook/confirm endpoint), never on client claim.
-- Purchase amounts are bounded and server-defined; clients cannot pick arbitrary
-  prices.
-- Confirmation is idempotent and audited (provider reference recorded).
-
-### US-3 Marketplace listing (sell)
-As a creator, I can list a catalog item for sale at a Credit price and
-manage/remove my listings.
-
-**Acceptance criteria**
-- A listing references a valid `catalog_item` owned by the seller (or an
-  authorized seller).
-- Price is bounded (min/max) and set server-side; status transitions are
-  explicit (`active`, `sold`, `delisted`, `removed_by_moderation`).
-- Only the seller (or a moderator) can update/remove a listing.
-- Listings are searchable/filterable (item type, price range, owner).
-
-### US-4 Marketplace purchase (buy)
-As a player, I can buy a listed item. The purchase is atomic, holds funds in
-escrow, grants the item, and splits the payment between platform and seller.
-
-**Acceptance criteria**
-- A single transaction debits the buyer, holds funds in escrow, and grants the
-  item — no partial states on failure.
-- Platform fee and seller net are computed server-side from the configured rate.
-- After the escrow hold window, funds move from escrow to the seller's
-  available balance.
-- Refunds during the hold window reverse the sale and return funds to the buyer.
-- Concurrent purchases of a one-of-a-kind listing cannot both succeed.
-
-### US-5 Creator payouts
-As a creator, I can view my earned balance, request a payout, and track its
-status; admins can review and approve/reject payouts.
-
-**Acceptance criteria**
-- Available balance is derived only from completed (escrow-released) sales and
-  completed payouts; it never goes negative.
-- Payout requests are bounded (min threshold, max per period) and rate-limited.
-- Large payouts require admin review; all payout requests carry an audit trail
-  (requested by, reviewed by, provider reference, status).
-- The payout provider is called exactly once; idempotent on retry.
-
-### US-6 Godot client
-As a player, I can manage Credits, browse/buy/sell marketplace items, and manage
-payouts from the game UI.
-
-**Acceptance criteria**
-- An API client handles JWT auth, HTTP, and idempotency keys for all economy
-  calls.
-- Dedicated screens: wallet + transaction history, marketplace browse/buy,
-  sell-listing, and creator payout.
-- The client never computes balances, fees, or seller nets — it only displays
-  server responses.
-
-## 6. Task breakdown
-
-Right-sized to 1–3 files / one coherent piece of functionality each. Task IDs
-are sequential for dependency chaining.
-
-| # | Task | Story | Depends on |
-|---|------|-------|-----------|
-| 1 | Wallet & ledger models + Alembic migration (`wallets`, `transactions`) | US-1 | — |
-| 2 | Wallet service (atomic credit/debit, idempotency, locking) + wallet/transactions API | US-1 | 1 |
-| 3 | Premium purchase: `PaymentProvider` interface + purchase/confirm endpoints | US-2 | 1 |
-| 4 | Catalog item & listing models + migration (`catalog_items`, `marketplace_listings`, `creator_balances`) | US-3 | 1 |
-| 5 | Marketplace listing API (create/list/search/update/remove) | US-3 | 4 |
-| 6 | Marketplace purchase service + API (atomic escrow, fee split, item grant) | US-4 | 2, 4, 5 |
-| 7 | Creator payout request models + API (`payout_requests`) | US-5 | 2, 6 |
-| 8 | Payout admin review + `PayoutProvider` + audit | US-5 | 7 |
-| 9 | Marketplace moderation + content-flag/age-gate enforcement | cross-cutting | 5, 6 |
-| 10 | Godot economy API client (auth + HTTP + idempotency) | US-6 | 2 |
-| 11 | Godot wallet & transaction history UI | US-6 | 10 |
-| 12 | Godot marketplace browse/buy UI | US-6 | 6, 10 |
-| 13 | Godot selling & payout UI | US-6 | 5, 7, 10 |
-
-## 7. Phasing
-
-- **Phase 1 (currency + payments):** tasks 1–3. The foundation — ledger and
-  money movement must be rock-solid before anything spends Credits.
-- **Phase 2 (marketplace):** tasks 4–6. Listing and atomic purchase with escrow.
-- **Phase 3 (payouts):** tasks 7–8. Turn released escrow into creator payouts.
-- **Phase 4 (moderation):** task 9. Lock down the marketplace against mature
-  content and abuse.
-- **Phase 5 (client):** tasks 10–13, each landing after its backend dependency.
-
-## 8. Data model sketch
-
-```text
-wallets
-  id                bigint PK
-  user_id           int UNIQUE FK -> users.id
-  balance           bigint NOT NULL DEFAULT 0  CHECK (balance >= 0)
-  created_at        timestamptz
-  updated_at        timestamptz
-
-transactions        (append-only ledger)
-  id                bigint PK
-  wallet_id         bigint FK -> wallets.id
-  type              enum(credit_purchase, marketplace_purchase,
-                        marketplace_sale, escrow_release, payout,
-                        refund, admin_adjustment)
-  amount            bigint NOT NULL            (signed)
-  balance_after     bigint NOT NULL
-  reference_type    text                        (e.g. "purchase", "sale", "payout_request")
-  reference_id      text
-  idempotency_key   text UNIQUE
-  metadata_json     jsonb
-  created_at        timestamptz
-
-catalog_items
-  id                bigint PK
-  owner_id          int FK -> users.id
-  asset_id          int FK -> assets.id (nullable; null for non-asset virtual items)
-  item_type         enum(asset, avatar_item, experience_pass)
-  name              text
-  description       text
-  metadata_json     jsonb
-  created_at        timestamptz
-
-marketplace_listings
-  id                bigint PK
-  catalog_item_id   bigint FK -> catalog_items.id
-  seller_id         int FK -> users.id
-  price             bigint NOT NULL CHECK (price > 0)
-  status            enum(active, sold, delisted, removed_by_moderation)
-  created_at        timestamptz
-  updated_at        timestamptz
-
-purchases
-  id                bigint PK
-  listing_id        bigint FK -> marketplace_listings.id
-  buyer_id          int FK -> users.id
-  seller_id         int FK -> users.id
-  price             bigint NOT NULL
-  platform_fee      bigint NOT NULL
-  seller_net        bigint NOT NULL
-  status            enum(pending_escrow, completed, refunded, reversed)
-  escrow_hold_until timestamptz
-  created_at        timestamptz
-
-creator_balances
-  id                bigint PK
-  user_id           int UNIQUE FK -> users.id
-  available         bigint NOT NULL DEFAULT 0
-  pending           bigint NOT NULL DEFAULT 0
-  lifetime_earned   bigint NOT NULL DEFAULT 0
-  updated_at        timestamptz
-
-payout_requests
-  id                bigint PK
-  creator_id        int FK -> users.id
-  amount            bigint NOT NULL CHECK (amount > 0)
-  status            enum(pending, approved, paid, rejected)
-  external_ref      text
-  provider_ref      text
-  requested_by      int FK -> users.id
-  reviewed_by       int FK -> users.id (nullable)
-  reviewed_at       timestamptz
-  created_at        timestamptz
-```
-
-## 9. Security, anti-fraud & audit
-
-- **Server-authoritative balances/fees:** clients never compute totals; amounts
-  are validated server-side against bounds and the current listing.
-- **Row locking:** wallet and creator-balance mutations use `SELECT ... FOR
-  UPDATE` within one transaction.
-- **Idempotency:** every money-moving endpoint requires an `Idempotency-Key`;
-  duplicate keys return the stored original outcome.
-- **Rate limiting:** purchase, listing, and payout endpoints are token-bucket
-  rate-limited per user.
-- **Escrow & reversibility:** funds are not payable until the hold window
-  elapses; chargebacks/refunds reverse before release.
-- **Moderation:** listings carry the item's effective content flags; mature
-  items require age verification (per `content_moderation.md`); moderators can
-  `delist`/`remove` and trigger audited reversals.
-- **Audit:** the ledger plus `payout_requests` review fields form an append-only
-  audit trail for every movement of value.
-
-## 10. Out of scope for this feature
-
-- Real Stripe/PayPal/KYC integrations (provider interfaces leave the hooks; the
-  defaults are deterministic no-ops).
-- Subscriptions, recurring billing, or premium memberships.
-- Gift cards, promotional codes, or user-to-user Credit transfers.
-- Partial refunds, chargeback disputes, and seller tax/VAT handling.
-- In-world vending machines / scripted economy triggers (future, built on this
-  ledger via the scripting sandbox).