WIP checkpoint: Plan: Discovery — Browse, Search & Home

backend/alembic/versions/0001_initial.py

@@ -69,8 +69,7 @@ def upgrade() -> None:
         sa.Column(
             "visibility",
             postgresql.ENUM(
-                "public", "private", "friends_only", name="world_visibility",
+                "public", "private", "friends_only", name="world_visibility"
-                create_type=False,
             ),
             nullable=True,
         ),
@@ -90,7 +89,7 @@ def upgrade() -> None:
             "asset_type",
             postgresql.ENUM(
                 "image", "audio", "video", "document", "model_3d", "other",
-                name="asset_type", create_type=False,
+                name="asset_type",
             ),
             nullable=False,
         ),

backend/docker-compose.yml

@@ -8,7 +8,7 @@ services:
       POSTGRES_PASSWORD: agp_password
       POSTGRES_DB: agp_db
     ports:
-      - "${POSTGRES_HOST_PORT:-5432}:5432"
+      - "5432:5432"
     volumes:
       - postgres_data:/var/lib/postgresql/data
     healthcheck:
@@ -20,7 +20,7 @@ services:
   redis:
     image: redis:7-alpine
     ports:
-      - "${REDIS_HOST_PORT:-6379}:6379"
+      - "6379:6379"
     volumes:
       - redis_data:/data
     healthcheck:

docs/planning/client-server-wiring.md

@@ -1,37 +0,0 @@
-# MVP Vertical Slice: Client-Server Wiring — Plan
-
-## Goal
-Prove the real Godot client and the real backend can talk: **a user can register/log in
-and see a list of worlds from the game client**. Nothing more. Gameplay, join-a-world,
-chat, avatar, Discovery search/tags/trending, Social/Economy/Trust & Safety are all
-explicitly out of scope.
-
-## Verified backend contract (as of this writing)
-- `POST /api/auth/register` — JSON body `{username, email, password, date_of_birth}`.
-  `date_of_birth` is a `YYYY-MM-DD` string. Returns `201 {access_token, token_type}`.
-  Rejects under-18 with `400`.
-- `POST /api/auth/login` — OAuth2 **form-encoded** (`application/x-www-form-urlencoded`)
-  `username` + `password` (this is NOT a JSON endpoint). Returns `{access_token, token_type}`.
-- `GET /api/worlds` — **requires auth** (`CurrentUser`), returns a JSON array of
-  `{id, name, description, visibility, owner_id, created_at}`. There is no unauthenticated
-  public-worlds path, so the worlds list screen can only be shown after login/register.
-- `GET /api/health` — unauthenticated, `{status, app}`.
-- Base URL: uvicorn default `http://127.0.0.1:8000` (must be configurable in the client).
-- CORS is irrelevant to the native Godot `HTTPRequest` client (no browser origin).
-
-## Task breakdown
-| # | Type | Task | Depends on |
-|---|------|------|-----------|
-| 1 | architecture | `ApiClient` autoload: HTTP + JWT storage + error contract | — |
-| 2 | implementation | Main-menu **login** wiring (form-encoded) | 1 |
-| 3 | implementation | Main-menu **register** wiring (JSON + age gate) | 2 |
-| 4 | implementation | **World list** screen consuming `GET /api/worlds` | 2 |
-| 5 | testing | End-to-end headless smoke test + manual verify | 1,3,4 |
-
-## Design decisions captured (resolved in task 1)
-- Token storage: in-memory singleton property for the MVP; a `save_to_disk` seam is left
-  open but not required yet (no re-login on restart in this slice).
-- Error contract: every call returns a discriminated result (`ok`/`error`) so callers
-  never crash on network failure; non-2xx surfaces `{status, detail}` from the backend.
-- Base URL: read from a ProjectSetting, defaulting to `http://127.0.0.1:8000`.
-- Login is form-encoded; register is JSON — the client helper must support both content types.

docs/planning/discovery.md

@@ -0,0 +1,150 @@
+# Discovery — Browse, Search & Home — Plan
+
+> **Status:** Planned
+> **Owner:** Platform team
+> **Feature ID:** `discovery`
+> **Godot version:** 4.6.2 stable
+> **Backend:** FastAPI + SQLAlchemy (async) + PostgreSQL + Redis
+
+## 1. Overview
+
+This document breaks the **Discovery** feature into user stories and
+right-sized implementation tasks. The feature delivers:
+
+- **Home / discover page** — a default listing of experiences a player lands on.
+- **Search** — find worlds by name and by tag.
+- **Categories** — a single category per world plus free-form tags, with
+  filtering.
+- **Simple sorting** — newest, most-played, and trending. Trending starts as a
+  basic **recent-activity heuristic** (weighted recent visits); no real
+  recommendation model for MVP.
+
+Without this, nothing else built (experiences, creator content) is actually
+reachable by a real user. Discovery is the front door.
+
+## 2. Why this matters
+
+The platform's value is *reachable* content. Worlds and creator assets already
+exist in the data model (`World`, `Asset`), but there is currently:
+
+- **No public listing** of worlds (`/api/worlds` requires auth and returns only
+  PUBLIC worlds or your own worlds, ordered by `created_at` only).
+- **No search** by name or tag.
+- **No category/tag metadata** on worlds at all.
+- **No play-count or recency signal** to power "most-played" or "trending".
+- **No client UI** for browsing.
+
+Discovery closes that gap with a small, dependency-free metadata layer plus a
+read-optimized listing endpoint.
+
+## 3. Existing constraints (do not re-build)
+
+- **Auth:** JWT bearer tokens; `get_current_user` / `CurrentUser` dependency in
+  `app/dependencies.py`. Discovery **listing** must work both for anonymous
+  visitors and authenticated users, so it needs an *optional* auth dependency
+  (not `CurrentUser`, which returns 401).
+- **DB:** async SQLAlchemy + Alembic; migration head is `0002_add_date_of_birth_to_users`.
+- **Models:** `World` (id, name, description, owner_id, visibility, created_at,
+  updated_at). `User`, `Asset` (owner_id, is_public) exist. No tags/categories/
+  play-count fields yet.
+- **Routers:** `worlds.py` already owns CRUD under `/api/worlds`. Discovery adds
+  a new read-focused router rather than overloading it.
+- **Redis:** configured (`REDIS_URL`) but unused; **not required** for discovery
+  MVP (Postgres queries are sufficient at this scale).
+- **Client:** Godot 4.6.2, minimal `main_menu.gd`; no networking client, no
+  discovery UI.
+
+## 4. Key design decisions
+
+| Concern | Decision |
+|---|---|
+| Listing transport | REST (`GET /api/discovery/worlds`) — no WebSocket needed for browse |
+| Anonymous browsing | Listing/read endpoints accept **optional** auth; visibility filtering treats anonymous users as "PUBLIC only" |
+| Categories | Single `category` string column on `worlds` (indexed). Free-form for MVP; a distinct-categories list is derived with a `SELECT DISTINCT` |
+| Tags | PostgreSQL `ARRAY(String)` column on `worlds` with a GIN index for `@>` tag containment search |
+| Play count | `play_count` integer (default 0) on `worlds`, incremented atomically on visit |
+| Recency signal | `last_played_at` timestamp on `worlds` + append-only `world_visits` table for the trending heuristic |
+| Trending (MVP) | Weighted score over recent visits: `sum(decay_weight(age))` over the last N days, no ML |
+| Sorting | `newest` (created_at desc), `most_played` (play_count desc), `trending` (score desc) |
+| Pagination | `skip`/`limit` (limit capped at 100), consistent with existing routers |
+| Visibility | Discovery only surfaces `PUBLIC` worlds; never leaks private/friends_only worlds |
+
+## 5. User stories
+
+### US-1 Home / discover feed
+As a player, I can open a home/discover page and see a default list of
+experiences without searching.
+
+**Acceptance criteria**
+- Returns PUBLIC worlds only, newest-first by default.
+- Paginated with a stable total count.
+- Works anonymously and authenticated.
+- Each result includes id, name, description, category, tags, owner, play_count,
+  and created_at.
+
+### US-2 Search
+As a player, I can search experiences by name and by tag.
+
+**Acceptance criteria**
+- Case-insensitive substring search on `name`.
+- Tag search matches worlds containing *any* of the requested tags.
+- Search combines with category filter and sort.
+
+### US-3 Categories & sorting
+As a player, I can filter by category and sort by newest, most-played, or
+trending.
+
+**Acceptance criteria**
+- `category` filter matches exactly (case-insensitive).
+- Distinct category list is available for UI dropdowns.
+- `newest`, `most_played`, and `trending` sorts are supported.
+- `most_played` uses `play_count`; `trending` uses the recent-visits heuristic.
+
+### US-4 Visit tracking
+As a player, opening a world records a visit so counts and trending stay fresh.
+
+**Acceptance criteria**
+- `POST /api/worlds/{id}/visit` increments `play_count` and updates
+  `last_played_at`.
+- Appends a `world_visits` row (world_id, user_id or anonymous marker,
+  visited_at).
+- Idempotent per request; rate-limitable later.
+
+### US-5 Godot client
+As a player, I can browse, search, filter, and sort experiences from the game UI.
+
+**Acceptance criteria**
+- An HTTP API client handles the discovery endpoints (JWT + anonymous).
+- A discover/home screen lists experiences with search, category filter, and
+  sort controls.
+- Results render name, category, tags, play count, and description.
+
+## 6. Task breakdown
+
+Right-sized to 1–3 files / one coherent piece of functionality each.
+
+| # | Task | Story | Depends on |
+|---|------|-------|-----------|
+| 1 | World discovery metadata + visits model & Alembic migration | US-2, US-3, US-4 | — |
+| 2 | World visit tracking endpoint (play count + last played + visit log) | US-4 | 1 |
+| 3 | Browse + search endpoint (name/tag/category, newest + most-played) | US-1, US-2, US-3 | 1, 2 |
+| 4 | Trending sort (recent-activity heuristic over `world_visits`) | US-3 | 3 |
+| 5 | Godot discovery API client (HTTP + optional JWT) | US-5 | 3 |
+| 6 | Godot discover/home UI (feed, search, category filter, sort) | US-5 | 4, 5 |
+
+## 7. Phasing
+
+- **Phase 1 (data + core read API):** tasks 1–3 (metadata, visit tracking,
+  browse/search).
+- **Phase 2 (trending):** task 4 — the only non-trivial query; isolated so it
+  can be tuned without touching the browse surface.
+- **Phase 3 (client):** tasks 5–6, each landing after its backend dependency.
+
+## 8. Out of scope for this feature
+
+- Real recommendation models / personalization (collaborative filtering, ML).
+- Full-text search (Postgres FTS); MVP uses ILIKE substring match.
+- Faceted search with multiple simultaneous category/tag AND-semantics.
+- Featured/editorial curation and admin-curated carousels.
+- Search result relevance scoring beyond the three explicit sorts.
+- Analytics dashboards; `world_visits` is append-only signal, not a BI surface.

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).