feat(godot): discovery API client with typed WorldSummary and DiscoveryResult parsing

backend/app/routers/discovery.py

@@ -16,6 +16,8 @@ from app.database import get_db
 from app.dependencies import OptionalUser
 from app.models.world import World, WorldVisibility
 from app.models.world_visit import WorldVisit
+from app.services.trending import get_trending_subquery
+
 
 router = APIRouter()
 
@@ -208,11 +210,23 @@ async def list_discovery_worlds(
     total = (await db.execute(count_query)).scalar_one()
 
     # Sort
-    if sort == "most_played":
+    if sort == "trending":
+        trending_subq = get_trending_subquery()
+        base_query = (
+            base_query
+            .outerjoin(trending_subq, World.id == trending_subq.c.trending_world_id)
+            .order_by(
+                func.coalesce(trending_subq.c.trending_score, 0.0).desc(),
+                World.play_count.desc(),
+                World.created_at.desc(),
+            )
+        )
+    elif sort == "most_played":
         base_query = base_query.order_by(World.play_count.desc(), World.created_at.desc())
     else:  # default: newest
         base_query = base_query.order_by(World.created_at.desc())
 
+
     # Pagination & load owner
     query = (
         base_query

backend/app/services/trending.py

@@ -0,0 +1,34 @@
+"""Trending recommendation heuristic service.
+
+docs/planning/discovery.md (task 33706f401ad9).
+"""
+
+from sqlalchemy import case, func, select, text
+from app.models.world_visit import WorldVisit
+
+
+def get_trending_subquery(days: int = 7):
+    """Build a subquery that computes a decay-weighted trending score per world_id.
+
+    Decay weights:
+    - Visited within 24 hours: weight 3.0
+    - Visited within 3 days: weight 2.0
+    - Visited within 7 days: weight 1.0
+    """
+    trending_weight = case(
+        (WorldVisit.visited_at >= func.now() - text("interval '1 day'"), 3.0),
+        (WorldVisit.visited_at >= func.now() - text("interval '3 days'"), 2.0),
+        else_=1.0,
+    )
+
+    interval_str = f"interval '{days} days'"
+    subq = (
+        select(
+            WorldVisit.world_id.label("trending_world_id"),
+            func.coalesce(func.sum(trending_weight), 0.0).label("trending_score"),
+        )
+        .where(WorldVisit.visited_at >= func.now() - text(interval_str))
+        .group_by(WorldVisit.world_id)
+        .subquery("trending_scores")
+    )
+    return subq

backend/tests/test_discovery_trending.py

@@ -0,0 +1,103 @@
+"""API and heuristic tests for trending discovery sort.
+
+docs/planning/discovery.md (task 33706f401ad9).
+"""
+
+from datetime import datetime, timedelta, timezone
+import pytest
+from fastapi.testclient import TestClient
+from sqlalchemy.ext.asyncio import async_sessionmaker, create_async_engine
+from sqlalchemy.pool import NullPool
+
+from app.config import settings
+from app.main import app
+from app.models.world_visit import WorldVisit
+
+
+def _register(client: TestClient, username: str) -> tuple[int, dict[str, str]]:
+    resp = client.post(
+        "/api/auth/register",
+        json={
+            "username": username,
+            "email": f"{username}@example.com",
+            "password": "secret123",
+            "date_of_birth": "1990-01-01",
+        },
+    )
+    assert resp.status_code == 201, resp.text
+    token = resp.json()["access_token"]
+    headers = {"Authorization": f"Bearer {token}"}
+    me = client.get("/api/users/me", headers=headers)
+    assert me.status_code == 200, me.text
+    return me.json()["id"], headers
+
+
+def _session_factory():
+    engine = create_async_engine(settings.DATABASE_URL, poolclass=NullPool)
+    return engine, async_sessionmaker(engine, expire_on_commit=False)
+
+
+@pytest.mark.asyncio
+async def test_trending_sort_heuristic_and_zero_visits():
+    client = TestClient(app)
+    uid, headers = _register(client, "creator_trending_1")
+
+    # Create 3 worlds
+    wA = client.post(
+        "/api/worlds/",
+        headers=headers,
+        json={"name": "Trending Hot World", "visibility": "public", "category": "Action"},
+    ).json()
+    wB = client.post(
+        "/api/worlds/",
+        headers=headers,
+        json={"name": "Older Mild World", "visibility": "public", "category": "Action"},
+    ).json()
+    wC = client.post(
+        "/api/worlds/",
+        headers=headers,
+        json={"name": "Zero Visit World", "visibility": "public", "category": "Action"},
+    ).json()
+
+    engine, sf = _session_factory()
+    now = datetime.now(timezone.utc)
+    try:
+        async with sf() as session:
+            # World A: 3 visits within last 2 hours (weight 3 each = score 9)
+            for i in range(3):
+                session.add(
+                    WorldVisit(
+                        world_id=wA["id"],
+                        anonymous_token=f"hot_visitor_{i}",
+                        visited_at=now - timedelta(hours=1, minutes=i),
+                    )
+                )
+            # World B: 1 visit 5 days ago (weight 1 = score 1)
+            session.add(
+                WorldVisit(
+                    world_id=wB["id"],
+                    anonymous_token="old_visitor",
+                    visited_at=now - timedelta(days=5),
+                )
+            )
+            # World C: zero visits
+            await session.commit()
+    finally:
+        await engine.dispose()
+
+    # Query with sort=trending
+    resp = client.get("/api/discovery/worlds?sort=trending&category=Action")
+    assert resp.status_code == 200, resp.text
+    items = resp.json()["items"]
+
+    # Verify order: wA should be first, wB second, wC third
+    ids = [item["id"] for item in items]
+    assert wA["id"] in ids
+    assert wB["id"] in ids
+    assert wC["id"] in ids
+
+    idxA = ids.index(wA["id"])
+    idxB = ids.index(wB["id"])
+    idxC = ids.index(wC["id"])
+
+    assert idxA < idxB < idxC, f"Expected order A ({idxA}) < B ({idxB}) < C ({idxC})"

scripts/api_client.gd

@@ -456,6 +456,31 @@ func report_message(message_id: int, conversation_type: String, reason: String,
 	return await SocialApiClient.report_message(self, message_id, conversation_type, reason, context_text)
 
 
+# ---------------------------------------------------------------------------
+# Discovery Features
+# ---------------------------------------------------------------------------
+
+## List public worlds for discovery with optional search, tags, category, and sort.
+func get_discovery_worlds(
+	q: String = "",
+	tags: Array = [],
+	category: String = "",
+	sort: String = "newest",
+	skip: int = 0,
+	limit: int = 50
+) -> Dictionary:
+	return await DiscoveryApiClient.get_worlds(self, q, tags, category, sort, skip, limit)
+
+## Get distinct categories of public worlds.
+func get_discovery_categories() -> Dictionary:
+	return await DiscoveryApiClient.get_categories(self)
+
+## Record a visit to a world.
+func record_world_visit(world_id: int, anonymous_token: String = "") -> Dictionary:
+	return await DiscoveryApiClient.record_visit(self, world_id, anonymous_token)
+
+
+
 
 # ---------------------------------------------------------------------------
 # Internals

scripts/discovery_api_client.gd

@@ -0,0 +1,140 @@
+extends RefCounted
+class_name DiscoveryApiClient
+## Helper client for AGP Discovery REST endpoints (Browse, Search, Categories, Visit tracking).
+##
+## docs/planning/discovery.md (task 56c49440d0a6).
+
+class WorldSummary extends RefCounted:
+	var id: int = 0
+	var name: String = ""
+	var description: String = ""
+	var category: String = ""
+	var tags: Array = []
+	var play_count: int = 0
+	var created_at: String = ""
+	var owner_id: int = 0
+	var owner_username: String = ""
+
+	static func from_dict(d: Dictionary) -> WorldSummary:
+		var w := WorldSummary.new()
+		w.id = int(d.get("id", 0))
+		w.name = str(d.get("name", ""))
+		w.description = str(d.get("description", "")) if d.get("description") != null else ""
+		w.category = str(d.get("category", "")) if d.get("category") != null else ""
+		var raw_tags = d.get("tags", [])
+		w.tags = raw_tags if raw_tags is Array else []
+		w.play_count = int(d.get("play_count", 0))
+		w.created_at = str(d.get("created_at", "")) if d.get("created_at") != null else ""
+		var owner: Dictionary = d.get("owner", {}) if d.get("owner") is Dictionary else {}
+		w.owner_id = int(owner.get("id", 0))
+		w.owner_username = str(owner.get("username", ""))
+		return w
+
+
+class DiscoveryResult extends RefCounted:
+	var items: Array[WorldSummary] = []
+	var total: int = 0
+	var skip: int = 0
+	var limit: int = 50
+
+	static func from_dict(d: Dictionary) -> DiscoveryResult:
+		var res := DiscoveryResult.new()
+		res.total = int(d.get("total", 0))
+		res.skip = int(d.get("skip", 0))
+		res.limit = int(d.get("limit", 50))
+		var raw_items = d.get("items", [])
+		if raw_items is Array:
+			for item in raw_items:
+				if item is Dictionary:
+					res.items.append(WorldSummary.from_dict(item))
+		return res
+
+
+static func get_api_client(node: Node) -> Node:
+	if node.has_node("/root/ApiClient"):
+		return node.get_node("/root/ApiClient")
+	return null
+
+
+## Fetch worlds with search, tags, category filter, sort, and pagination.
+## Attaches JWT token if client has one; works anonymously without token.
+## Surfaces transport/HTTP errors in the standard result dictionary.
+static func get_worlds(
+	api: Node,
+	q: String = "",
+	tags: Array = [],
+	category: String = "",
+	sort: String = "newest",
+	skip: int = 0,
+	limit: int = 50
+) -> Dictionary:
+	var params: Array[String] = []
+	if q != "":
+		params.append("q=" + q.uri_encode())
+	if tags.size() > 0:
+		var tag_strs: Array[String] = []
+		for t in tags:
+			tag_strs.append(str(t))
+		params.append("tags=" + ",".join(tag_strs).uri_encode())
+	if category != "":
+		params.append("category=" + category.uri_encode())
+	if sort != "":
+		params.append("sort=" + sort.uri_encode())
+	params.append("skip=%d" % skip)
+	params.append("limit=%d" % limit)
+
+	var url := "/api/discovery/worlds"
+	if params.size() > 0:
+		url += "?" + "&".join(params)
+
+	var custom_headers := PackedStringArray()
+	if api != null and api.has_method("has_token") and api.has_token():
+		custom_headers.append("Authorization: " + api.bearer_token)
+
+	var res: Dictionary = await api.request(
+		HTTPClient.METHOD_GET,
+		url,
+		"",
+		"application/json",
+		false,
+		custom_headers
+	)
+	if res.ok and res.data is Dictionary:
+		res["parsed"] = DiscoveryResult.from_dict(res.data)
+	return res
+
+
+## Fetch distinct categories of public worlds.
+static func get_categories(api: Node) -> Dictionary:
+	var custom_headers := PackedStringArray()
+	if api != null and api.has_method("has_token") and api.has_token():
+		custom_headers.append("Authorization: " + api.bearer_token)
+
+	return await api.request(
+		HTTPClient.METHOD_GET,
+		"/api/discovery/categories",
+		"",
+		"application/json",
+		false,
+		custom_headers
+	)
+
+
+## Record a visit to a world. Supports optional anonymous token or logged in user.
+static func record_visit(api: Node, world_id: int, anonymous_token: String = "") -> Dictionary:
+	var custom_headers := PackedStringArray()
+	if api != null and api.has_method("has_token") and api.has_token():
+		custom_headers.append("Authorization: " + api.bearer_token)
+
+	var payload := {}
+	if anonymous_token != "":
+		payload["anonymous_token"] = anonymous_token
+
+	return await api.request(
+		HTTPClient.METHOD_POST,
+		"/api/discovery/worlds/%d/visit" % world_id,
+		JSON.stringify(payload) if payload.size() > 0 else "",
+		"application/json",
+		false,
+		custom_headers
+	)

scripts/smoke_test_discovery_client.gd

@@ -0,0 +1,62 @@
+extends SceneTree
+## Headless smoke test for DiscoveryApiClient.
+
+func _init() -> void:
+	print("[SMOKE] Starting DiscoveryApiClient smoke test...")
+
+	# 1. Test WorldSummary parsing
+	var test_dict := {
+		"id": 42,
+		"name": "Neon Arcade",
+		"description": "Retro gaming lounge",
+		"category": "Arcade",
+		"tags": ["retro", "multiplayer"],
+		"play_count": 128,
+		"created_at": "2026-09-15T12:00:00Z",
+		"owner": {
+			"id": 7,
+			"username": "arcadegamer"
+		}
+	}
+
+	var summary := DiscoveryApiClient.WorldSummary.from_dict(test_dict)
+	assert(summary.id == 42, "summary id mismatch")
+	assert(summary.name == "Neon Arcade", "summary name mismatch")
+	assert(summary.category == "Arcade", "summary category mismatch")
+	assert(summary.tags.size() == 2, "summary tags size mismatch")
+	assert(summary.play_count == 128, "summary play_count mismatch")
+	assert(summary.owner_id == 7, "summary owner_id mismatch")
+	assert(summary.owner_username == "arcadegamer", "summary owner_username mismatch")
+	print("[PASS] WorldSummary parsing verified")
+
+	# 2. Test DiscoveryResult parsing
+	var page_dict := {
+		"items": [test_dict],
+		"total": 1,
+		"skip": 0,
+		"limit": 50
+	}
+	var res := DiscoveryApiClient.DiscoveryResult.from_dict(page_dict)
+	assert(res.total == 1, "res total mismatch")
+	assert(res.items.size() == 1, "res items size mismatch")
+	assert(res.items[0].id == 42, "res items[0] id mismatch")
+	print("[PASS] DiscoveryResult parsing verified")
+
+	# 3. Test ApiClient integration
+	var api_script = load("res://scripts/api_client.gd")
+	if not api_script:
+		printerr("[FAIL] Could not load api_client.gd")
+		quit(1)
+		return
+
+	var api: Node = api_script.new()
+	root.add_child(api)
+
+	assert(api.has_method("get_discovery_worlds"), "Missing get_discovery_worlds on ApiClient")
+	assert(api.has_method("get_discovery_categories"), "Missing get_discovery_categories on ApiClient")
+	assert(api.has_method("record_world_visit"), "Missing record_world_visit on ApiClient")
+	print("[PASS] ApiClient discovery methods verified")
+
+	api.queue_free()
+	print("[SMOKE] DiscoveryApiClient smoke test PASSED")
+	quit(0)