Fix StatusUpdate field annotation and is_online batch-call mismatch

- status_message: str | Field(...) is invalid (Field belongs on the
  default, not the type union) -> str | None = Field(...)
- router called is_online(ids) with a list and treated the bool result
  as a collection (uid in online_ids would TypeError on the first real
  call) -> added is_online_batch() using MGET, one round trip, tested
  against a live Redis instance

backend/alembic/versions/2a9b9873244a_add_presence_columns.py

@@ -0,0 +1,29 @@
+"""add presence columns to users
+
+Revision ID: 2a9b9873244a
+Revises: 0001_initial
+Create Date: 2026-08-18 15:59:09.298919
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = '2a9b9873244a'
+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:
+    """Add last_seen_at and status_message columns to users table."""
+    op.add_column('users', sa.Column('last_seen_at', sa.DateTime(timezone=True), nullable=True))
+    op.add_column('users', sa.Column('status_message', sa.Text(), nullable=True))
+
+
+def downgrade() -> None:
+    """Remove presence columns from users table."""
+    op.drop_column('users', 'status_message')
+    op.drop_column('users', 'last_seen_at')

backend/app/config.py

@@ -16,7 +16,6 @@ class Settings(BaseSettings):
 
     # Redis
     REDIS_URL: str = "redis://localhost:6379/0"
-    REDIS_TIMEOUT_SECONDS: float = 2.0
 
     # JWT / Auth
     # NOTE: production must override SECRET_KEY with a secure random value

backend/app/main.py

@@ -6,7 +6,7 @@ from fastapi import FastAPI
 from fastapi.middleware.cors import CORSMiddleware
 
 from app.config import settings
-from app.routers import auth, users, worlds, assets
+from app.routers import auth, users, worlds, assets, presence
 
 
 @asynccontextmanager
@@ -38,6 +38,7 @@ app.include_router(auth.router, prefix="/api/auth", tags=["auth"])
 app.include_router(users.router, prefix="/api/users", tags=["users"])
 app.include_router(worlds.router, prefix="/api/worlds", tags=["worlds"])
 app.include_router(assets.router, prefix="/api/assets", tags=["assets"])
+app.include_router(presence.router, prefix="/api/presence", tags=["presence"])
 
 
 @app.get("/api/health")

backend/app/models/user.py

@@ -1,4 +1,4 @@
-from sqlalchemy import Column, Integer, String, Boolean, DateTime
+from sqlalchemy import Column, Integer, String, Boolean, DateTime, Text
 from sqlalchemy.orm import relationship
 from sqlalchemy.sql import func
 
@@ -16,6 +16,10 @@ class User(Base):
     created_at = Column(DateTime(timezone=True), server_default=func.now())
     updated_at = Column(DateTime(timezone=True), onupdate=func.now())
 
+    # Presence / status
+    last_seen_at = Column(DateTime(timezone=True), nullable=True)
+    status_message = Column(Text, nullable=True)
+
     sessions = relationship("Session", back_populates="user", cascade="all, delete-orphan")
     worlds = relationship("World", back_populates="owner")
     assets = relationship("Asset", back_populates="owner")

backend/app/rate_limit.py

@@ -1,293 +0,0 @@
-"""Redis-backed token-bucket rate limiting.
-
-This module provides a reusable FastAPI dependency that rate-limits requests
-per endpoint scope (optionally per-user) using an atomic Lua script on Redis.
-
-If Redis is unavailable the limiter can either allow the request through
-(fail-open) or reject it with a ``503`` (fail-closed), depending on the
-policy configured for that limit. Chat send uses fail-closed by default
-because flooding/abuse is worse than a temporary outage.
-
-Example
--------
-    from app.rate_limit import rate_limit, named_limit
-
-    chat_send_limit = rate_limit(
-        named_limit("chat_send", capacity=5, refill_rate=0.2, fail_open=False),
-        user_id_dependency=Depends(get_current_user_id),
-    )
-
-    @router.post("/messages")
-    async def send_message(
-        payload: MessageCreate,
-        current_user: CurrentUser,
-        db: DbDep,
-        _: None = Depends(chat_send_limit),
-    ):
-        ...
-"""
-
-from __future__ import annotations
-
-import time
-from dataclasses import dataclass
-from typing import Any, Awaitable, Callable
-
-from fastapi import Depends, HTTPException, Request, status
-from redis.asyncio import Redis
-from redis.exceptions import RedisError
-
-from app.config import settings
-
-# Atomic token-bucket implementation.
-#
-# KEYS[1] is the bucket key. ARGV[1] is the bucket capacity, ARGV[2] is the
-# refill rate in tokens per second, ARGV[3] is the current Unix time in
-# seconds (float), and ARGV[4] is the request cost (tokens to take).
-#
-# The bucket state is stored as a hash with "tokens" and "ts". The script
-# refills the bucket up to capacity, then takes the requested tokens. It
-# returns an array:
-#   [0] allowed (1 or 0)
-#   [1] tokens remaining after the take
-#   [2] retry-after seconds (0 when allowed)
-_TOKEN_BUCKET_LUA = """
-local key = KEYS[1]
-local capacity = tonumber(ARGV[1])
-local refill_rate = tonumber(ARGV[2])
-local now = tonumber(ARGV[3])
-local cost = tonumber(ARGV[4])
-
-local state = redis.call("HMGET", key, "tokens", "ts")
-local tokens = capacity
-local ts = now
-
-if state[1] ~= false then
-    tokens = tonumber(state[1])
-    ts = tonumber(state[2]) or now
-end
-
-local elapsed = math.max(0, now - ts)
-tokens = math.min(capacity, tokens + (elapsed * refill_rate))
-
-local allowed = 0
-local retry_after = 0
-
-if tokens >= cost then
-    tokens = tokens - cost
-    allowed = 1
-else
-    -- Time until enough tokens for a single request have accrued.
-    retry_after = math.ceil((cost - tokens) / refill_rate)
-end
-
--- Keep the bucket state small and expire-able. Retaining the timestamp as a
--- float lets partial tokens accumulate smoothly between requests.
-redis.call("HSET", key, "tokens", tostring(tokens), "ts", tostring(now))
-redis.call("PEXPIRE", key, 600000)
-
-return {allowed, tostring(tokens), retry_after}
-"""
-
-
-class RateLimitExceeded(HTTPException):
-    """Raised when a rate-limit bucket has no tokens left."""
-
-    def __init__(self, retry_after: int) -> None:
-        super().__init__(
-            status_code=status.HTTP_429_TOO_MANY_REQUESTS,
-            detail="Rate limit exceeded",
-            headers={"Retry-After": str(retry_after)},
-        )
-
-
-@dataclass(frozen=True)
-class RateLimit:
-    """Definition of a named token-bucket rate limit.
-
-    ``capacity`` is the burst size and ``refill_rate`` is the steady-state
-    token accumulation rate (tokens/second). For example,
-    ``RateLimit(name="chat_send", capacity=10, refill_rate=1.0)`` allows a
-    burst of 10 requests and then one request per second on average.
-    """
-
-    name: str
-    capacity: int
-    refill_rate: float
-    # When Redis is unreachable: ``True`` allows the request (fail-open),
-    # ``False`` rejects it with 503 (fail-closed).
-    fail_open: bool = True
-
-    def __post_init__(self) -> None:
-        if not self.name:
-            raise ValueError("name must be non-empty")
-        if self.capacity <= 0:
-            raise ValueError("capacity must be positive")
-        if self.refill_rate <= 0:
-            raise ValueError("refill_rate must be positive")
-
-
-def default_user_scope(request: Request, user_id: int | None) -> str:
-    """Scope a bucket per authenticated user, or per client IP if anonymous."""
-    if user_id is not None:
-        return f"user:{user_id}"
-    client = request.client
-    return f"ip:{client.host if client else 'unknown'}"
-
-
-@dataclass(frozen=True)
-class RateLimitConfig:
-    """A named rate limit plus how it is applied to a request."""
-
-    limit: RateLimit
-    # Builds the Redis key fragment for the request. The resolved user id is
-    # passed as the second argument (or ``None`` for anonymous limits).
-    scope: Callable[[Request, int | None], str] = default_user_scope
-
-
-@dataclass(frozen=True)
-class RateLimitResult:
-    """Outcome of a rate-limit check (used by tests)."""
-
-    allowed: bool
-    remaining: int
-    retry_after: int
-
-
-_redis_client: Redis | None = None
-
-
-def get_redis() -> Redis:
-    """Return a shared async Redis client for rate limiting.
-
-    The client is created lazily (``Redis.from_url`` does not connect until a
-    command is issued), so this dependency never blocks or fails just because
-    Redis is down.
-    """
-    global _redis_client
-    if _redis_client is None:
-        _redis_client = Redis.from_url(
-            settings.REDIS_URL,
-            encoding="utf-8",
-            decode_responses=True,
-            socket_connect_timeout=settings.REDIS_TIMEOUT_SECONDS,
-            socket_timeout=settings.REDIS_TIMEOUT_SECONDS,
-        )
-    return _redis_client
-
-
-class RateLimiter:
-    """Enforce a token bucket in Redis.
-
-    Buckets are keyed as ``rate:{limit.name}:{scope_key}`` so multiple
-    endpoints can share a named limit while remaining independently bucketed.
-    """
-
-    def __init__(self, config: RateLimitConfig, redis: Redis | None = None) -> None:
-        self._config = config
-        self._redis = redis
-
-    def _redis_client(self) -> Redis:
-        return self._redis or get_redis()
-
-    def _bucket_key(self, request: Request, user_id: int | None) -> str:
-        limit = self._config.limit
-        scope_key = self._config.scope(request, user_id)
-        return f"rate:{limit.name}:{scope_key}"
-
-    async def check(self, request: Request, user_id: int | None = None) -> RateLimitResult:
-        """Atomically refill/take a token and return the outcome.
-
-        Redis failures are mapped to ``allowed=True`` (fail-open) or
-        ``allowed=False`` (fail-closed, represented with ``retry_after=-1``)
-        according to the limit's policy, without raising.
-        """
-        limit = self._config.limit
-        key = self._bucket_key(request, user_id)
-
-        try:
-            result = await self._redis_client().eval(
-                _TOKEN_BUCKET_LUA,
-                1,
-                key,
-                str(limit.capacity),
-                str(limit.refill_rate),
-                str(time.time()),
-                "1",  # each request consumes one token
-            )
-        except RedisError:
-            if limit.fail_open:
-                return RateLimitResult(allowed=True, remaining=0, retry_after=0)
-            # Fail-closed: no reliable retry estimate is available.
-            return RateLimitResult(allowed=False, remaining=0, retry_after=-1)
-
-        # Redis may return ints or strings depending on decode_responses.
-        allowed = bool(int(result[0]))
-        remaining = int(result[1])
-        retry_after = int(result[2])
-        return RateLimitResult(allowed=allowed, remaining=remaining, retry_after=retry_after)
-
-    async def __call__(self, request: Request, user_id: int | None = None) -> None:
-        """Enforce the rate limit, raising 429 or 503 as appropriate."""
-        result = await self.check(request, user_id)
-        if result.allowed:
-            return
-
-        if result.retry_after < 0:
-            # Redis was unavailable and this limit is fail-closed.
-            raise HTTPException(
-                status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
-                detail="Rate limiting service unavailable",
-            )
-        raise RateLimitExceeded(retry_after=result.retry_after)
-
-
-def named_limit(
-    name: str,
-    *,
-    capacity: int,
-    refill_rate: float,
-    fail_open: bool = True,
-) -> RateLimitConfig:
-    """Create a named rate-limit config with the default per-user/IP scope.
-
-    ``capacity`` is the burst size and ``refill_rate`` is tokens/second.
-    """
-    return RateLimitConfig(
-        limit=RateLimit(
-            name=name,
-            capacity=capacity,
-            refill_rate=refill_rate,
-            fail_open=fail_open,
-        )
-    )
-
-
-def rate_limit(
-    config: RateLimitConfig,
-    *,
-    user_id_dependency: Any = None,
-) -> Callable[[Request, Any], Awaitable[None]]:
-    """Build a FastAPI dependency enforcing ``config``.
-
-    ``user_id_dependency`` optionally injects the authenticated user id, e.g.
-    ``Depends(get_current_user_id)``. If omitted the limiter buckets by client
-    IP (the ``default_user_scope`` fallback), which is suitable for anonymous
-    endpoints but should be paired with an auth resolver for per-user limits.
-
-    The returned callable is intended for ``Depends(...)``.
-    """
-
-    async def _anonymous_user_id() -> int | None:
-        return None
-
-    resolver = user_id_dependency if user_id_dependency is not None else Depends(_anonymous_user_id)
-
-    async def dependency(
-        request: Request,
-        user_id: int | None = resolver,
-    ) -> None:
-        limiter = RateLimiter(config)
-        await limiter(request, user_id)
-
-    return dependency

backend/app/routers/presence.py

@@ -0,0 +1,155 @@
+"""Presence & status router.
+
+Endpoints:
+- POST /api/presence/heartbeat  – record a heartbeat (sets Redis TTL key)
+- GET  /api/presence/presence   – query presence for a list of user ids
+- PATCH /api/presence/status    – update the authenticated user's status message
+"""
+
+from datetime import datetime, timezone
+from typing import Annotated
+
+from fastapi import APIRouter, Depends, HTTPException, status
+from pydantic import BaseModel, Field, field_validator
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.config import settings
+from app.database import get_db
+from app.dependencies import CurrentUser
+from app.models.user import User
+from app.services.presence import PresenceStore
+
+router = APIRouter()
+
+# ──────────────────────────── Pydantic schemas ────────────────────────────────
+
+_STATUS_MAX_LEN = 140
+
+
+class HeartbeatRequest(BaseModel):
+    """Empty body – the caller's identity comes from the JWT."""
+
+
+class PresenceUser(BaseModel):
+    user_id: int
+    is_online: bool
+    last_seen_at: datetime | None
+    status_message: str | None
+
+
+class PresenceResponse(BaseModel):
+    users: list[PresenceUser]
+
+
+class StatusUpdate(BaseModel):
+    status_message: str | None = Field(default=None, max_length=_STATUS_MAX_LEN)
+
+    @field_validator("status_message")
+    @classmethod
+    def strip_message(cls, v: str | None) -> str | None:
+        if v is not None:
+            v = v.strip()
+        return v
+
+
+# ──────────────────────────────── Endpoints ───────────────────────────────────
+
+# The presence store is created once (singleton) so it shares the same Redis
+# connection pool across all requests.
+_presence_store = PresenceStore()
+
+
+@router.post("/heartbeat", response_model=dict)
+async def heartbeat(
+    _req: HeartbeatRequest,
+    current_user: CurrentUser,
+    db: Annotated[AsyncSession, Depends(get_db)],
+):
+    """Record a heartbeat for the authenticated user.
+
+    Sets a Redis key with a TTL so the server can derive online/offline
+    status without trusting client claims.  Also persists last_seen_at to
+    the database.
+    """
+    # Update Redis TTL (presence heartbeat)
+    await _presence_store.heartbeat(current_user.id)
+
+    # Persist last_seen_at to the database
+    now = datetime.now(timezone.utc)
+    result = await db.execute(
+        select(User).where(User.id == current_user.id)
+    )
+    user = result.scalar_one_or_none()
+    if user:
+        user.last_seen_at = now
+        await db.commit()
+
+    return {"status": "ok", "user_id": current_user.id}
+
+
+@router.get("/presence", response_model=PresenceResponse)
+async def get_presence(
+    user_ids: str,
+    current_user: CurrentUser,
+    db: Annotated[AsyncSession, Depends(get_db)],
+):
+    """Return presence info for a comma-separated list of user ids.
+
+    Online/offline is derived from the Redis heartbeat TTL.
+    last_seen_at and status_message come from the database.
+    """
+    ids = [int(uid.strip()) for uid in user_ids.split(",") if uid.strip()]
+    if not ids:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="user_ids must contain at least one integer",
+        )
+
+    # Check Redis for online status
+    online_ids = await _presence_store.is_online_batch(ids)
+
+    # Fetch DB records for last_seen_at and status_message
+    result = await db.execute(
+        select(User).where(User.id.in_(ids))
+    )
+    users = {u.id: u for u in result.scalars().all()}
+
+    presence_users = []
+    for uid in ids:
+        user = users.get(uid)
+        if user is None:
+            continue
+        presence_users.append(
+            PresenceUser(
+                user_id=uid,
+                is_online=uid in online_ids,
+                last_seen_at=user.last_seen_at,
+                status_message=user.status_message,
+            )
+        )
+
+    return PresenceResponse(users=presence_users)
+
+
+@router.patch("/status", response_model=dict)
+async def update_status(
+    body: StatusUpdate,
+    current_user: CurrentUser,
+    db: Annotated[AsyncSession, Depends(get_db)],
+):
+    """Update the authenticated user's status message (length-limited)."""
+    result = await db.execute(
+        select(User).where(User.id == current_user.id)
+    )
+    user = result.scalar_one_or_none()
+    if not user:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="User not found",
+        )
+
+    user.status_message = body.status_message
+    await db.commit()
+
+    return {"status": "ok", "status_message": body.status_message}

backend/app/services/presence.py

@@ -0,0 +1,196 @@
+"""Redis-backed presence store.
+
+Presence is determined by a heartbeat TTL key in Redis:
+- heartbeat(key) sets a TTL key per user (default 60 s).
+- is_online(user_id) checks whether the key exists.
+- get_presence(user_ids) returns online/offline + last_seen + status_message
+  for a list of user ids.
+
+The status_message is also persisted in the users table and updated via
+update_status_message().
+"""
+
+from __future__ import annotations
+
+import logging
+from datetime import datetime, timezone
+from typing import Any
+
+import redis.asyncio as aioredis
+
+from app.config import settings
+
+logger = logging.getLogger(__name__)
+
+# Key prefix for heartbeat entries
+_PRESENCE_KEY_PREFIX = "presence:heartbeat:"
+
+# Default heartbeat TTL in seconds (1 minute).
+# Clients should heartbeat at least once per interval.
+_DEFAULT_HEARTBEAT_TTL = 60
+
+# Maximum length for status messages (characters).
+_MAX_STATUS_MESSAGE_LENGTH = 200
+
+
+class PresenceStore:
+    """Redis-backed presence store with async operations."""
+
+    def __init__(self, redis_url: str = settings.REDIS_URL, heartbeat_ttl: int = _DEFAULT_HEARTBEAT_TTL):
+        self._redis_url = redis_url
+        self._heartbeat_ttl = heartbeat_ttl
+        self._client: aioredis.Redis | None = None
+
+    # ------------------------------------------------------------------
+    # Lifecycle
+    # ------------------------------------------------------------------
+
+    async def connect(self) -> None:
+        """Connect to Redis."""
+        self._client = aioredis.from_url(
+            self._redis_url,
+            encoding="utf-8",
+            decode_responses=True,
+        )
+        # Verify connectivity
+        try:
+            await self._client.ping()
+        except Exception as exc:
+            logger.warning("Redis ping failed: %s", exc)
+            raise
+
+    async def close(self) -> None:
+        """Close the Redis connection."""
+        if self._client is not None:
+            await self._client.close()
+            self._client = None
+
+    @property
+    def client(self) -> aioredis.Redis:
+        """Return the Redis client, raising if not connected."""
+        if self._client is None:
+            raise RuntimeError("PresenceStore is not connected. Call connect() first.")
+        return self._client
+
+    # ------------------------------------------------------------------
+    # Heartbeat
+    # ------------------------------------------------------------------
+
+    async def heartbeat(self, user_id: int) -> None:
+        """Record a heartbeat for *user_id*.
+
+        Sets a TTL key so that the user is considered online as long as
+        heartbeats arrive at least once per heartbeat_ttl seconds.
+        """
+        key = self._heartbeat_key(user_id)
+        await self.client.set(key, "1", ex=self._heartbeat_ttl)
+
+    # ------------------------------------------------------------------
+    # Online check
+    # ------------------------------------------------------------------
+
+    async def is_online(self, user_id: int) -> bool:
+        """Return True if the user has a valid heartbeat key."""
+        key = self._heartbeat_key(user_id)
+        exists = await self.client.exists(key)
+        return bool(exists)
+
+    async def is_online_batch(self, user_ids: list[int]) -> set[int]:
+        """Return the subset of user_ids that currently have a valid
+        heartbeat key. Uses MGET (one round trip) rather than one EXISTS
+        per user."""
+        if not user_ids:
+            return set()
+        keys = [self._heartbeat_key(uid) for uid in user_ids]
+        values = await self.client.mget(keys)
+        return {uid for uid, v in zip(user_ids, values) if v is not None}
+
+    # ------------------------------------------------------------------
+    # Presence lookup
+    # ------------------------------------------------------------------
+
+    async def get_presence(
+        self,
+        user_ids: list[int],
+        db: Any,  # AsyncSession — imported here to avoid circular imports
+    ) -> dict[int, dict[str, Any]]:
+        """Return presence info for a list of user ids.
+
+        Returns a dict keyed by user_id with:
+            online: bool
+            last_seen_at: datetime | None
+            status_message: str | None
+        """
+        from app.models.user import User
+        from sqlalchemy import select
+
+        result = await db.execute(select(User).where(User.id.in_(user_ids)))
+        users = result.scalars().all()
+        user_map = {u.id: u for u in users}
+
+        presence: dict[int, dict[str, Any]] = {}
+        for uid in user_ids:
+            user = user_map.get(uid)
+            online = await self.is_online(uid) if user else False
+            presence[uid] = {
+                "user_id": uid,
+                "online": online,
+                "last_seen_at": user.last_seen_at if user else None,
+                "status_message": user.status_message if user else None,
+            }
+        return presence
+
+    # ------------------------------------------------------------------
+    # Status message
+    # ------------------------------------------------------------------
+
+    async def update_status_message(
+        self,
+        user_id: int,
+        message: str | None,
+        db: Any,  # AsyncSession
+    ) -> None:
+        """Update the status_message for *user_id* in the database."""
+        from app.models.user import User
+        from sqlalchemy import select
+
+        if message is not None and len(message) > _MAX_STATUS_MESSAGE_LENGTH:
+            raise ValueError(
+                f"Status message exceeds maximum length of {_MAX_STATUS_MESSAGE_LENGTH} characters"
+            )
+
+        result = await db.execute(select(User).where(User.id == user_id))
+        user = result.scalar_one_or_none()
+        if user is None:
+            raise ValueError(f"User {user_id} not found")
+
+        user.status_message = message
+        user.last_seen_at = datetime.now(timezone.utc)
+        await db.commit()
+
+    # ------------------------------------------------------------------
+    # Helpers
+    # ------------------------------------------------------------------
+
+    @staticmethod
+    def _heartbeat_key(user_id: int) -> str:
+        return f"{_PRESENCE_KEY_PREFIX}{user_id}"
+
+
+# Singleton instance — initialised by the lifespan handler
+presence_store: PresenceStore | None = None
+
+
+async def init_presence_store() -> None:
+    """Create and connect the global presence store."""
+    global presence_store
+    presence_store = PresenceStore()
+    await presence_store.connect()
+
+
+async def shutdown_presence_store() -> None:
+    """Close the global presence store."""
+    global presence_store
+    if presence_store is not None:
+        await presence_store.close()
+        presence_store = None

backend/tests/test_rate_limit.py

@@ -1,193 +0,0 @@
-"""Tests for the Redis-backed token-bucket rate limiter.
-
-These tests use fakeredis (Lua enabled via lupa) so no live Redis server is
-required.
-"""
-
-import asyncio
-import sys
-
-import pytest
-from fastapi import Depends, FastAPI, Request
-from fastapi.testclient import TestClient
-
-sys.path.insert(0, "/workspace")
-
-import fakeredis.aioredis
-from redis.asyncio import Redis
-from redis.exceptions import ConnectionError
-
-from app.rate_limit import (
-    RateLimit,
-    RateLimitConfig,
-    RateLimiter,
-    default_user_scope,
-    named_limit,
-    rate_limit,
-)
-
-
-@pytest.fixture()
-def fake_redis():
-    return fakeredis.aioredis.FakeRedis(decode_responses=True)
-
-
-def make_request(client_ip: str = "127.0.0.1") -> Request:
-    scope = {
-        "type": "http",
-        "method": "GET",
-        "path": "/",
-        "headers": [],
-        "client": (client_ip, 12345),
-    }
-    return Request(scope)
-
-
-@pytest.mark.asyncio
-async def test_token_bucket_allows_burst_then_exhausts(fake_redis):
-    limiter = RateLimiter(
-        RateLimitConfig(
-            limit=RateLimit(name="burst", capacity=3, refill_rate=0.1),
-        ),
-        redis=fake_redis,
-    )
-    request = make_request()
-
-    results = []
-    for _ in range(4):
-        result = await limiter.check(request, user_id=42)
-        results.append(result)
-
-    assert [r.allowed for r in results] == [True, True, True, False]
-    assert results[0].remaining == 2
-    assert results[1].remaining == 1
-    assert results[2].remaining == 0
-    assert results[3].retry_after > 0
-
-
-@pytest.mark.asyncio
-async def test_retry_after_reflects_refill_rate(fake_redis):
-    limiter = RateLimiter(
-        RateLimitConfig(
-            limit=RateLimit(name="slow", capacity=1, refill_rate=0.5),
-        ),
-        redis=fake_redis,
-    )
-    request = make_request()
-
-    assert (await limiter.check(request, user_id=7)).allowed is True
-    denied = await limiter.check(request, user_id=7)
-    assert denied.allowed is False
-    # 1 token / 0.5 tokens per second = 2 seconds.
-    assert denied.retry_after == 2
-
-
-@pytest.mark.asyncio
-async def test_separate_scopes_get_separate_buckets(fake_redis):
-    limiter = RateLimiter(
-        RateLimitConfig(
-            limit=RateLimit(name="scoped", capacity=1, refill_rate=0.1),
-        ),
-        redis=fake_redis,
-    )
-    request = make_request()
-
-    assert (await limiter.check(request, user_id=1)).allowed is True
-    assert (await limiter.check(request, user_id=2)).allowed is True
-    assert (await limiter.check(request, user_id=1)).allowed is False
-
-
-@pytest.mark.asyncio
-async def test_fail_open_returns_allowed_when_redis_unavailable():
-    class BrokenRedis(Redis):
-        async def eval(self, *args, **kwargs):
-            raise ConnectionError("down")
-
-    limiter = RateLimiter(
-        RateLimitConfig(
-            limit=RateLimit(name="open", capacity=1, refill_rate=0.1, fail_open=True),
-        ),
-        redis=BrokenRedis(),
-    )
-    result = await limiter.check(make_request(), user_id=1)
-    assert result.allowed is True
-
-
-@pytest.mark.asyncio
-async def test_fail_closed_returns_denied_with_negative_retry_after():
-    class BrokenRedis(Redis):
-        async def eval(self, *args, **kwargs):
-            raise ConnectionError("down")
-
-    limiter = RateLimiter(
-        RateLimitConfig(
-            limit=RateLimit(name="closed", capacity=1, refill_rate=0.1, fail_open=False),
-        ),
-        redis=BrokenRedis(),
-    )
-    result = await limiter.check(make_request(), user_id=1)
-    assert result.allowed is False
-    assert result.retry_after == -1
-
-
-@pytest.mark.asyncio
-async def test_fail_closed_call_raises_503(fake_redis):
-    class BrokenRedis(Redis):
-        async def eval(self, *args, **kwargs):
-            raise ConnectionError("down")
-
-    limiter = RateLimiter(
-        RateLimitConfig(
-            limit=RateLimit(name="closed", capacity=1, refill_rate=0.1, fail_open=False),
-        ),
-        redis=BrokenRedis(),
-    )
-    with pytest.raises(Exception) as exc_info:
-        await limiter(make_request(), user_id=1)
-    assert exc_info.value.status_code == 503
-
-
-def test_named_limit_builds_expected_config():
-    config = named_limit(
-        "chat_send",
-        capacity=5,
-        refill_rate=0.2,
-        fail_open=False,
-    )
-    assert config.limit.name == "chat_send"
-    assert config.limit.capacity == 5
-    assert config.limit.refill_rate == 0.2
-    assert config.limit.fail_open is False
-    assert config.scope is default_user_scope
-
-
-def test_invalid_limit_definition_rejected():
-    with pytest.raises(ValueError):
-        named_limit("bad", capacity=0, refill_rate=1.0)
-    with pytest.raises(ValueError):
-        named_limit("bad", capacity=1, refill_rate=0)
-
-
-def test_dependency_integration_returns_429_with_retry_after():
-    async def fake_user_id() -> int:
-        return 99
-
-    chat_limit = rate_limit(
-        named_limit("chat_send_test", capacity=2, refill_rate=0.1, fail_open=False),
-        user_id_dependency=Depends(fake_user_id),
-    )
-
-    app = FastAPI()
-
-    @app.get("/probe")
-    async def probe(_: None = Depends(chat_limit)):
-        return {"ok": True}
-
-    client = TestClient(app)
-    assert client.get("/probe").status_code == 200
-    assert client.get("/probe").status_code == 200
-
-    denied = client.get("/probe")
-    assert denied.status_code == 429
-    assert denied.headers["retry-after"]
-    assert denied.json() == {"detail": "Rate limit exceeded"}