feat(memory): add working memory implementation (Issue #89)

Implements session-scoped ephemeral memory with:

Storage Backends:
- InMemoryStorage: Thread-safe fallback with TTL support and capacity limits
- RedisStorage: Primary storage with connection pooling and JSON serialization
- Auto-fallback from Redis to in-memory when unavailable

WorkingMemory Class:
- Key-value storage with TTL and reserved key protection
- Task state tracking with progress updates
- Scratchpad for reasoning steps with timestamps
- Checkpoint/snapshot support for recovery
- Factory methods for auto-configured storage

Tests:
- 55 unit tests covering all functionality
- Tests for basic ops, TTL, capacity, concurrency
- Tests for task state, scratchpad, checkpoints

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/services/memory/exceptions.py

@@ -94,6 +94,22 @@ class MemoryStorageError(MemoryError):
         self.backend = backend
 
 
+class MemoryConnectionError(MemoryError):
+    """Raised when memory storage connection fails."""
+
+    def __init__(
+        self,
+        message: str = "Memory connection failed",
+        *,
+        backend: str | None = None,
+        host: str | None = None,
+        **kwargs: Any,
+    ) -> None:
+        super().__init__(message, **kwargs)
+        self.backend = backend
+        self.host = host
+
+
 class MemorySerializationError(MemoryError):
     """Raised when memory serialization/deserialization fails."""
 

backend/app/services/memory/working/__init__.py

@@ -1,8 +1,16 @@
+# app/services/memory/working/__init__.py
 """
-Working Memory
+Working Memory Implementation.
 
-Session-scoped ephemeral memory for current task state,
+Provides short-term memory storage with Redis primary and in-memory fallback.
-variables, and scratchpad.
 """
 
-# Will be populated in #89
+from .memory import WorkingMemory
+from .storage import InMemoryStorage, RedisStorage, WorkingMemoryStorage
+
+__all__ = [
+    "InMemoryStorage",
+    "RedisStorage",
+    "WorkingMemory",
+    "WorkingMemoryStorage",
+]

backend/app/services/memory/working/memory.py

@@ -0,0 +1,543 @@
+# app/services/memory/working/memory.py
+"""
+Working Memory Implementation.
+
+Provides session-scoped ephemeral memory with:
+- Key-value storage with TTL
+- Task state tracking
+- Scratchpad for reasoning steps
+- Checkpoint/snapshot support
+"""
+
+import logging
+import uuid
+from dataclasses import asdict
+from datetime import UTC, datetime
+from typing import Any
+
+from app.services.memory.config import get_memory_settings
+from app.services.memory.exceptions import (
+    MemoryConnectionError,
+    MemoryNotFoundError,
+)
+from app.services.memory.types import ScopeContext, ScopeLevel, TaskState
+
+from .storage import InMemoryStorage, RedisStorage, WorkingMemoryStorage
+
+logger = logging.getLogger(__name__)
+
+
+# Reserved key prefixes for internal use
+_TASK_STATE_KEY = "_task_state"
+_SCRATCHPAD_KEY = "_scratchpad"
+_CHECKPOINT_PREFIX = "_checkpoint:"
+_METADATA_KEY = "_metadata"
+
+
+class WorkingMemory:
+    """
+    Session-scoped working memory.
+
+    Provides ephemeral storage for agent's current task context:
+    - Variables and intermediate data
+    - Task state (current step, status, progress)
+    - Scratchpad for reasoning steps
+    - Checkpoints for recovery
+
+    Uses Redis as primary storage with in-memory fallback.
+    """
+
+    def __init__(
+        self,
+        scope: ScopeContext,
+        storage: WorkingMemoryStorage,
+        default_ttl_seconds: int | None = None,
+    ) -> None:
+        """
+        Initialize working memory for a scope.
+
+        Args:
+            scope: The scope context (session, agent instance, etc.)
+            storage: Storage backend (use create() factory for auto-configuration)
+            default_ttl_seconds: Default TTL for keys (None = no expiration)
+        """
+        self._scope = scope
+        self._storage: WorkingMemoryStorage = storage
+        self._default_ttl = default_ttl_seconds
+        self._using_fallback = False
+        self._initialized = False
+
+    @classmethod
+    async def create(
+        cls,
+        scope: ScopeContext,
+        default_ttl_seconds: int | None = None,
+    ) -> "WorkingMemory":
+        """
+        Factory method to create WorkingMemory with auto-configured storage.
+
+        Attempts Redis first, falls back to in-memory if unavailable.
+        """
+        settings = get_memory_settings()
+        key_prefix = f"wm:{scope.to_key_prefix()}:"
+        storage: WorkingMemoryStorage
+
+        # Try Redis first
+        if settings.working_memory_backend == "redis":
+            redis_storage = RedisStorage(key_prefix=key_prefix)
+            try:
+                if await redis_storage.is_healthy():
+                    logger.debug(f"Using Redis storage for scope {scope.scope_id}")
+                    instance = cls(
+                        scope=scope,
+                        storage=redis_storage,
+                        default_ttl_seconds=default_ttl_seconds
+                        or settings.working_memory_default_ttl_seconds,
+                    )
+                    await instance._initialize()
+                    return instance
+            except MemoryConnectionError:
+                logger.warning("Redis unavailable, falling back to in-memory storage")
+                await redis_storage.close()
+
+        # Fall back to in-memory
+        storage = InMemoryStorage(
+            max_keys=settings.working_memory_max_items_per_session
+        )
+        instance = cls(
+            scope=scope,
+            storage=storage,
+            default_ttl_seconds=default_ttl_seconds
+            or settings.working_memory_default_ttl_seconds,
+        )
+        instance._using_fallback = True
+        await instance._initialize()
+        return instance
+
+    @classmethod
+    async def for_session(
+        cls,
+        session_id: str,
+        project_id: str | None = None,
+        agent_instance_id: str | None = None,
+    ) -> "WorkingMemory":
+        """
+        Convenience factory for session-scoped working memory.
+
+        Args:
+            session_id: Unique session identifier
+            project_id: Optional project context
+            agent_instance_id: Optional agent instance context
+        """
+        # Build scope hierarchy
+        parent = None
+        if project_id:
+            parent = ScopeContext(
+                scope_type=ScopeLevel.PROJECT,
+                scope_id=project_id,
+            )
+            if agent_instance_id:
+                parent = ScopeContext(
+                    scope_type=ScopeLevel.AGENT_INSTANCE,
+                    scope_id=agent_instance_id,
+                    parent=parent,
+                )
+
+        scope = ScopeContext(
+            scope_type=ScopeLevel.SESSION,
+            scope_id=session_id,
+            parent=parent,
+        )
+
+        return await cls.create(scope=scope)
+
+    async def _initialize(self) -> None:
+        """Initialize working memory metadata."""
+        if self._initialized:
+            return
+
+        metadata = {
+            "scope_type": self._scope.scope_type.value,
+            "scope_id": self._scope.scope_id,
+            "created_at": datetime.now(UTC).isoformat(),
+            "using_fallback": self._using_fallback,
+        }
+        await self._storage.set(_METADATA_KEY, metadata)
+        self._initialized = True
+
+    @property
+    def scope(self) -> ScopeContext:
+        """Get the scope context."""
+        return self._scope
+
+    @property
+    def is_using_fallback(self) -> bool:
+        """Check if using fallback in-memory storage."""
+        return self._using_fallback
+
+    # =========================================================================
+    # Basic Key-Value Operations
+    # =========================================================================
+
+    async def set(
+        self,
+        key: str,
+        value: Any,
+        ttl_seconds: int | None = None,
+    ) -> None:
+        """
+        Store a value.
+
+        Args:
+            key: The key to store under
+            value: The value to store (must be JSON-serializable)
+            ttl_seconds: Optional TTL (uses default if not specified)
+        """
+        if key.startswith("_"):
+            raise ValueError("Keys starting with '_' are reserved for internal use")
+
+        ttl = ttl_seconds if ttl_seconds is not None else self._default_ttl
+        await self._storage.set(key, value, ttl)
+
+    async def get(self, key: str, default: Any = None) -> Any:
+        """
+        Get a value.
+
+        Args:
+            key: The key to retrieve
+            default: Default value if key not found
+
+        Returns:
+            The stored value or default
+        """
+        result = await self._storage.get(key)
+        return result if result is not None else default
+
+    async def delete(self, key: str) -> bool:
+        """
+        Delete a key.
+
+        Args:
+            key: The key to delete
+
+        Returns:
+            True if the key existed
+        """
+        if key.startswith("_"):
+            raise ValueError("Cannot delete internal keys directly")
+        return await self._storage.delete(key)
+
+    async def exists(self, key: str) -> bool:
+        """
+        Check if a key exists.
+
+        Args:
+            key: The key to check
+
+        Returns:
+            True if the key exists
+        """
+        return await self._storage.exists(key)
+
+    async def list_keys(self, pattern: str = "*") -> list[str]:
+        """
+        List keys matching a pattern.
+
+        Args:
+            pattern: Glob-style pattern (default "*" for all)
+
+        Returns:
+            List of matching keys (excludes internal keys)
+        """
+        all_keys = await self._storage.list_keys(pattern)
+        return [k for k in all_keys if not k.startswith("_")]
+
+    async def get_all(self) -> dict[str, Any]:
+        """
+        Get all user key-value pairs.
+
+        Returns:
+            Dictionary of all key-value pairs (excludes internal keys)
+        """
+        all_data = await self._storage.get_all()
+        return {k: v for k, v in all_data.items() if not k.startswith("_")}
+
+    async def clear(self) -> int:
+        """
+        Clear all user keys (preserves internal state).
+
+        Returns:
+            Number of keys deleted
+        """
+        # Save internal state
+        task_state = await self._storage.get(_TASK_STATE_KEY)
+        scratchpad = await self._storage.get(_SCRATCHPAD_KEY)
+        metadata = await self._storage.get(_METADATA_KEY)
+
+        count = await self._storage.clear()
+
+        # Restore internal state
+        if metadata is not None:
+            await self._storage.set(_METADATA_KEY, metadata)
+        if task_state is not None:
+            await self._storage.set(_TASK_STATE_KEY, task_state)
+        if scratchpad is not None:
+            await self._storage.set(_SCRATCHPAD_KEY, scratchpad)
+
+        # Adjust count for preserved keys
+        preserved = sum(1 for x in [task_state, scratchpad, metadata] if x is not None)
+        return max(0, count - preserved)
+
+    # =========================================================================
+    # Task State Operations
+    # =========================================================================
+
+    async def set_task_state(self, state: TaskState) -> None:
+        """
+        Set the current task state.
+
+        Args:
+            state: The task state to store
+        """
+        state.updated_at = datetime.now(UTC)
+        await self._storage.set(_TASK_STATE_KEY, asdict(state))
+
+    async def get_task_state(self) -> TaskState | None:
+        """
+        Get the current task state.
+
+        Returns:
+            The current TaskState or None if not set
+        """
+        data = await self._storage.get(_TASK_STATE_KEY)
+        if data is None:
+            return None
+
+        # Convert datetime strings back to datetime objects
+        if isinstance(data.get("started_at"), str):
+            data["started_at"] = datetime.fromisoformat(data["started_at"])
+        if isinstance(data.get("updated_at"), str):
+            data["updated_at"] = datetime.fromisoformat(data["updated_at"])
+
+        return TaskState(**data)
+
+    async def update_task_progress(
+        self,
+        current_step: int | None = None,
+        progress_percent: float | None = None,
+        status: str | None = None,
+    ) -> TaskState | None:
+        """
+        Update task progress fields.
+
+        Args:
+            current_step: New current step number
+            progress_percent: New progress percentage (0.0 to 100.0)
+            status: New status string
+
+        Returns:
+            Updated TaskState or None if no task state exists
+        """
+        state = await self.get_task_state()
+        if state is None:
+            return None
+
+        if current_step is not None:
+            state.current_step = current_step
+        if progress_percent is not None:
+            state.progress_percent = min(100.0, max(0.0, progress_percent))
+        if status is not None:
+            state.status = status
+
+        await self.set_task_state(state)
+        return state
+
+    # =========================================================================
+    # Scratchpad Operations
+    # =========================================================================
+
+    async def append_scratchpad(self, content: str) -> None:
+        """
+        Append content to the scratchpad.
+
+        Args:
+            content: Text to append
+        """
+        settings = get_memory_settings()
+        entries = await self._storage.get(_SCRATCHPAD_KEY) or []
+
+        # Check capacity
+        if len(entries) >= settings.working_memory_max_items_per_session:
+            # Remove oldest entries
+            entries = entries[-(settings.working_memory_max_items_per_session - 1) :]
+
+        entry = {
+            "content": content,
+            "timestamp": datetime.now(UTC).isoformat(),
+        }
+        entries.append(entry)
+        await self._storage.set(_SCRATCHPAD_KEY, entries)
+
+    async def get_scratchpad(self) -> list[str]:
+        """
+        Get all scratchpad entries.
+
+        Returns:
+            List of scratchpad content strings (ordered by time)
+        """
+        entries = await self._storage.get(_SCRATCHPAD_KEY) or []
+        return [e["content"] for e in entries]
+
+    async def get_scratchpad_with_timestamps(self) -> list[dict[str, Any]]:
+        """
+        Get all scratchpad entries with timestamps.
+
+        Returns:
+            List of dicts with 'content' and 'timestamp' keys
+        """
+        return await self._storage.get(_SCRATCHPAD_KEY) or []
+
+    async def clear_scratchpad(self) -> int:
+        """
+        Clear the scratchpad.
+
+        Returns:
+            Number of entries cleared
+        """
+        entries = await self._storage.get(_SCRATCHPAD_KEY) or []
+        count = len(entries)
+        await self._storage.set(_SCRATCHPAD_KEY, [])
+        return count
+
+    # =========================================================================
+    # Checkpoint Operations
+    # =========================================================================
+
+    async def create_checkpoint(self, description: str = "") -> str:
+        """
+        Create a checkpoint of current state.
+
+        Args:
+            description: Optional description of the checkpoint
+
+        Returns:
+            Checkpoint ID for later restoration
+        """
+        checkpoint_id = str(uuid.uuid4())[:8]
+        checkpoint_key = f"{_CHECKPOINT_PREFIX}{checkpoint_id}"
+
+        # Capture all current state
+        all_data = await self._storage.get_all()
+
+        checkpoint = {
+            "id": checkpoint_id,
+            "description": description,
+            "created_at": datetime.now(UTC).isoformat(),
+            "data": all_data,
+        }
+
+        await self._storage.set(checkpoint_key, checkpoint)
+        logger.debug(f"Created checkpoint {checkpoint_id}")
+        return checkpoint_id
+
+    async def restore_checkpoint(self, checkpoint_id: str) -> None:
+        """
+        Restore state from a checkpoint.
+
+        Args:
+            checkpoint_id: ID of the checkpoint to restore
+
+        Raises:
+            MemoryNotFoundError: If checkpoint not found
+        """
+        checkpoint_key = f"{_CHECKPOINT_PREFIX}{checkpoint_id}"
+        checkpoint = await self._storage.get(checkpoint_key)
+
+        if checkpoint is None:
+            raise MemoryNotFoundError(f"Checkpoint {checkpoint_id} not found")
+
+        # Clear current state
+        await self._storage.clear()
+
+        # Restore all data from checkpoint
+        for key, value in checkpoint["data"].items():
+            await self._storage.set(key, value)
+
+        # Keep the checkpoint itself
+        await self._storage.set(checkpoint_key, checkpoint)
+
+        logger.debug(f"Restored checkpoint {checkpoint_id}")
+
+    async def list_checkpoints(self) -> list[dict[str, Any]]:
+        """
+        List all available checkpoints.
+
+        Returns:
+            List of checkpoint metadata (id, description, created_at)
+        """
+        checkpoint_keys = await self._storage.list_keys(f"{_CHECKPOINT_PREFIX}*")
+        checkpoints = []
+
+        for key in checkpoint_keys:
+            data = await self._storage.get(key)
+            if data:
+                checkpoints.append(
+                    {
+                        "id": data["id"],
+                        "description": data["description"],
+                        "created_at": data["created_at"],
+                    }
+                )
+
+        # Sort by creation time
+        checkpoints.sort(key=lambda x: x["created_at"])
+        return checkpoints
+
+    async def delete_checkpoint(self, checkpoint_id: str) -> bool:
+        """
+        Delete a checkpoint.
+
+        Args:
+            checkpoint_id: ID of the checkpoint to delete
+
+        Returns:
+            True if checkpoint existed
+        """
+        checkpoint_key = f"{_CHECKPOINT_PREFIX}{checkpoint_id}"
+        return await self._storage.delete(checkpoint_key)
+
+    # =========================================================================
+    # Health and Lifecycle
+    # =========================================================================
+
+    async def is_healthy(self) -> bool:
+        """Check if the working memory storage is healthy."""
+        return await self._storage.is_healthy()
+
+    async def close(self) -> None:
+        """Close the working memory storage."""
+        if self._storage:
+            await self._storage.close()
+
+    async def get_stats(self) -> dict[str, Any]:
+        """
+        Get working memory statistics.
+
+        Returns:
+            Dictionary with stats about current state
+        """
+        all_keys = await self._storage.list_keys("*")
+        user_keys = [k for k in all_keys if not k.startswith("_")]
+        checkpoint_keys = [k for k in all_keys if k.startswith(_CHECKPOINT_PREFIX)]
+        scratchpad = await self._storage.get(_SCRATCHPAD_KEY) or []
+
+        return {
+            "scope_type": self._scope.scope_type.value,
+            "scope_id": self._scope.scope_id,
+            "using_fallback": self._using_fallback,
+            "total_keys": len(all_keys),
+            "user_keys": len(user_keys),
+            "checkpoint_count": len(checkpoint_keys),
+            "scratchpad_entries": len(scratchpad),
+            "has_task_state": await self._storage.exists(_TASK_STATE_KEY),
+        }

backend/app/services/memory/working/storage.py

@@ -0,0 +1,406 @@
+# app/services/memory/working/storage.py
+"""
+Working Memory Storage Backends.
+
+Provides abstract storage interface and implementations:
+- RedisStorage: Primary storage using Redis with connection pooling
+- InMemoryStorage: Fallback storage when Redis is unavailable
+"""
+
+import asyncio
+import fnmatch
+import json
+import logging
+from abc import ABC, abstractmethod
+from datetime import UTC, datetime, timedelta
+from typing import Any
+
+from app.services.memory.config import get_memory_settings
+from app.services.memory.exceptions import (
+    MemoryConnectionError,
+    MemoryStorageError,
+)
+
+logger = logging.getLogger(__name__)
+
+
+class WorkingMemoryStorage(ABC):
+    """Abstract base class for working memory storage backends."""
+
+    @abstractmethod
+    async def set(
+        self,
+        key: str,
+        value: Any,
+        ttl_seconds: int | None = None,
+    ) -> None:
+        """Store a value with optional TTL."""
+        ...
+
+    @abstractmethod
+    async def get(self, key: str) -> Any | None:
+        """Get a value by key, returns None if not found or expired."""
+        ...
+
+    @abstractmethod
+    async def delete(self, key: str) -> bool:
+        """Delete a key, returns True if existed."""
+        ...
+
+    @abstractmethod
+    async def exists(self, key: str) -> bool:
+        """Check if a key exists and is not expired."""
+        ...
+
+    @abstractmethod
+    async def list_keys(self, pattern: str = "*") -> list[str]:
+        """List all keys matching a pattern."""
+        ...
+
+    @abstractmethod
+    async def get_all(self) -> dict[str, Any]:
+        """Get all key-value pairs."""
+        ...
+
+    @abstractmethod
+    async def clear(self) -> int:
+        """Clear all keys, returns count of deleted keys."""
+        ...
+
+    @abstractmethod
+    async def is_healthy(self) -> bool:
+        """Check if the storage backend is healthy."""
+        ...
+
+    @abstractmethod
+    async def close(self) -> None:
+        """Close the storage connection."""
+        ...
+
+
+class InMemoryStorage(WorkingMemoryStorage):
+    """
+    In-memory storage backend for working memory.
+
+    Used as fallback when Redis is unavailable. Data is not persisted
+    across restarts and is not shared between processes.
+    """
+
+    def __init__(self, max_keys: int = 10000) -> None:
+        """Initialize in-memory storage."""
+        self._data: dict[str, Any] = {}
+        self._expirations: dict[str, datetime] = {}
+        self._max_keys = max_keys
+        self._lock = asyncio.Lock()
+
+    def _is_expired(self, key: str) -> bool:
+        """Check if a key has expired."""
+        if key not in self._expirations:
+            return False
+        return datetime.now(UTC) > self._expirations[key]
+
+    def _cleanup_expired(self) -> None:
+        """Remove all expired keys."""
+        now = datetime.now(UTC)
+        expired_keys = [
+            key for key, exp_time in self._expirations.items() if now > exp_time
+        ]
+        for key in expired_keys:
+            self._data.pop(key, None)
+            self._expirations.pop(key, None)
+
+    async def set(
+        self,
+        key: str,
+        value: Any,
+        ttl_seconds: int | None = None,
+    ) -> None:
+        """Store a value with optional TTL."""
+        async with self._lock:
+            # Cleanup expired keys periodically
+            if len(self._data) % 100 == 0:
+                self._cleanup_expired()
+
+            # Check capacity
+            if key not in self._data and len(self._data) >= self._max_keys:
+                # Evict expired keys first
+                self._cleanup_expired()
+                if len(self._data) >= self._max_keys:
+                    raise MemoryStorageError(
+                        f"Working memory capacity exceeded: {self._max_keys} keys"
+                    )
+
+            self._data[key] = value
+            if ttl_seconds is not None:
+                self._expirations[key] = datetime.now(UTC) + timedelta(
+                    seconds=ttl_seconds
+                )
+            elif key in self._expirations:
+                # Remove existing expiration if no TTL specified
+                del self._expirations[key]
+
+    async def get(self, key: str) -> Any | None:
+        """Get a value by key."""
+        async with self._lock:
+            if key not in self._data:
+                return None
+            if self._is_expired(key):
+                del self._data[key]
+                del self._expirations[key]
+                return None
+            return self._data[key]
+
+    async def delete(self, key: str) -> bool:
+        """Delete a key."""
+        async with self._lock:
+            existed = key in self._data
+            self._data.pop(key, None)
+            self._expirations.pop(key, None)
+            return existed
+
+    async def exists(self, key: str) -> bool:
+        """Check if a key exists and is not expired."""
+        async with self._lock:
+            if key not in self._data:
+                return False
+            if self._is_expired(key):
+                del self._data[key]
+                del self._expirations[key]
+                return False
+            return True
+
+    async def list_keys(self, pattern: str = "*") -> list[str]:
+        """List all keys matching a pattern."""
+        async with self._lock:
+            self._cleanup_expired()
+            if pattern == "*":
+                return list(self._data.keys())
+            return [key for key in self._data.keys() if fnmatch.fnmatch(key, pattern)]
+
+    async def get_all(self) -> dict[str, Any]:
+        """Get all key-value pairs."""
+        async with self._lock:
+            self._cleanup_expired()
+            return dict(self._data)
+
+    async def clear(self) -> int:
+        """Clear all keys."""
+        async with self._lock:
+            count = len(self._data)
+            self._data.clear()
+            self._expirations.clear()
+            return count
+
+    async def is_healthy(self) -> bool:
+        """In-memory storage is always healthy."""
+        return True
+
+    async def close(self) -> None:
+        """No cleanup needed for in-memory storage."""
+
+
+class RedisStorage(WorkingMemoryStorage):
+    """
+    Redis storage backend for working memory.
+
+    Primary storage with connection pooling, automatic reconnection,
+    and proper serialization of Python objects.
+    """
+
+    def __init__(
+        self,
+        key_prefix: str = "",
+        connection_timeout: float = 5.0,
+        socket_timeout: float = 5.0,
+    ) -> None:
+        """
+        Initialize Redis storage.
+
+        Args:
+            key_prefix: Prefix for all keys (e.g., "session:abc123:")
+            connection_timeout: Timeout for establishing connections
+            socket_timeout: Timeout for socket operations
+        """
+        self._key_prefix = key_prefix
+        self._connection_timeout = connection_timeout
+        self._socket_timeout = socket_timeout
+        self._redis: Any = None
+        self._lock = asyncio.Lock()
+
+    def _make_key(self, key: str) -> str:
+        """Add prefix to key."""
+        return f"{self._key_prefix}{key}"
+
+    def _strip_prefix(self, key: str) -> str:
+        """Remove prefix from key."""
+        if key.startswith(self._key_prefix):
+            return key[len(self._key_prefix) :]
+        return key
+
+    def _serialize(self, value: Any) -> str:
+        """Serialize a Python value to JSON string."""
+        return json.dumps(value, default=str)
+
+    def _deserialize(self, data: str | bytes | None) -> Any | None:
+        """Deserialize a JSON string to Python value."""
+        if data is None:
+            return None
+        if isinstance(data, bytes):
+            data = data.decode("utf-8")
+        return json.loads(data)
+
+    async def _get_client(self) -> Any:
+        """Get or create Redis client."""
+        if self._redis is not None:
+            return self._redis
+
+        async with self._lock:
+            if self._redis is not None:
+                return self._redis
+
+            try:
+                import redis.asyncio as aioredis
+            except ImportError as e:
+                raise MemoryConnectionError(
+                    "redis package not installed. Install with: pip install redis"
+                ) from e
+
+            settings = get_memory_settings()
+            redis_url = settings.redis_url
+
+            try:
+                self._redis = await aioredis.from_url(
+                    redis_url,
+                    encoding="utf-8",
+                    decode_responses=True,
+                    socket_connect_timeout=self._connection_timeout,
+                    socket_timeout=self._socket_timeout,
+                )
+                # Test connection
+                await self._redis.ping()
+                logger.info("Connected to Redis for working memory")
+                return self._redis
+            except Exception as e:
+                self._redis = None
+                raise MemoryConnectionError(f"Failed to connect to Redis: {e}") from e
+
+    async def set(
+        self,
+        key: str,
+        value: Any,
+        ttl_seconds: int | None = None,
+    ) -> None:
+        """Store a value with optional TTL."""
+        try:
+            client = await self._get_client()
+            full_key = self._make_key(key)
+            serialized = self._serialize(value)
+
+            if ttl_seconds is not None:
+                await client.setex(full_key, ttl_seconds, serialized)
+            else:
+                await client.set(full_key, serialized)
+        except MemoryConnectionError:
+            raise
+        except Exception as e:
+            raise MemoryStorageError(f"Failed to set key {key}: {e}") from e
+
+    async def get(self, key: str) -> Any | None:
+        """Get a value by key."""
+        try:
+            client = await self._get_client()
+            full_key = self._make_key(key)
+            data = await client.get(full_key)
+            return self._deserialize(data)
+        except MemoryConnectionError:
+            raise
+        except Exception as e:
+            raise MemoryStorageError(f"Failed to get key {key}: {e}") from e
+
+    async def delete(self, key: str) -> bool:
+        """Delete a key."""
+        try:
+            client = await self._get_client()
+            full_key = self._make_key(key)
+            result = await client.delete(full_key)
+            return bool(result)
+        except MemoryConnectionError:
+            raise
+        except Exception as e:
+            raise MemoryStorageError(f"Failed to delete key {key}: {e}") from e
+
+    async def exists(self, key: str) -> bool:
+        """Check if a key exists."""
+        try:
+            client = await self._get_client()
+            full_key = self._make_key(key)
+            result = await client.exists(full_key)
+            return bool(result)
+        except MemoryConnectionError:
+            raise
+        except Exception as e:
+            raise MemoryStorageError(f"Failed to check key {key}: {e}") from e
+
+    async def list_keys(self, pattern: str = "*") -> list[str]:
+        """List all keys matching a pattern."""
+        try:
+            client = await self._get_client()
+            full_pattern = self._make_key(pattern)
+            keys = await client.keys(full_pattern)
+            return [self._strip_prefix(key) for key in keys]
+        except MemoryConnectionError:
+            raise
+        except Exception as e:
+            raise MemoryStorageError(f"Failed to list keys: {e}") from e
+
+    async def get_all(self) -> dict[str, Any]:
+        """Get all key-value pairs."""
+        try:
+            client = await self._get_client()
+            full_pattern = self._make_key("*")
+            keys = await client.keys(full_pattern)
+
+            if not keys:
+                return {}
+
+            values = await client.mget(*keys)
+            result = {}
+            for key, value in zip(keys, values, strict=False):
+                stripped_key = self._strip_prefix(key)
+                result[stripped_key] = self._deserialize(value)
+            return result
+        except MemoryConnectionError:
+            raise
+        except Exception as e:
+            raise MemoryStorageError(f"Failed to get all keys: {e}") from e
+
+    async def clear(self) -> int:
+        """Clear all keys with this prefix."""
+        try:
+            client = await self._get_client()
+            full_pattern = self._make_key("*")
+            keys = await client.keys(full_pattern)
+
+            if not keys:
+                return 0
+
+            return await client.delete(*keys)
+        except MemoryConnectionError:
+            raise
+        except Exception as e:
+            raise MemoryStorageError(f"Failed to clear keys: {e}") from e
+
+    async def is_healthy(self) -> bool:
+        """Check if Redis connection is healthy."""
+        try:
+            client = await self._get_client()
+            await client.ping()
+            return True
+        except Exception:
+            return False
+
+    async def close(self) -> None:
+        """Close the Redis connection."""
+        if self._redis is not None:
+            await self._redis.close()
+            self._redis = None

backend/tests/unit/services/memory/working/__init__.py

@@ -0,0 +1,2 @@
+# tests/unit/services/memory/working/__init__.py
+"""Unit tests for working memory implementation."""

backend/tests/unit/services/memory/working/test_memory.py

@@ -0,0 +1,391 @@
+# tests/unit/services/memory/working/test_memory.py
+"""Unit tests for WorkingMemory class."""
+
+import pytest
+import pytest_asyncio
+
+from app.services.memory.exceptions import MemoryNotFoundError
+from app.services.memory.types import ScopeContext, ScopeLevel, TaskState
+from app.services.memory.working.memory import WorkingMemory
+from app.services.memory.working.storage import InMemoryStorage
+
+
+@pytest.fixture
+def scope() -> ScopeContext:
+    """Create a test scope."""
+    return ScopeContext(
+        scope_type=ScopeLevel.SESSION,
+        scope_id="test-session-123",
+    )
+
+
+@pytest.fixture
+def storage() -> InMemoryStorage:
+    """Create a test storage backend."""
+    return InMemoryStorage(max_keys=1000)
+
+
+@pytest_asyncio.fixture
+async def memory(scope: ScopeContext, storage: InMemoryStorage) -> WorkingMemory:
+    """Create a WorkingMemory instance for testing."""
+    wm = WorkingMemory(scope=scope, storage=storage)
+    await wm._initialize()
+    return wm
+
+
+class TestWorkingMemoryBasicOperations:
+    """Tests for basic key-value operations."""
+
+    @pytest.mark.asyncio
+    async def test_set_and_get(self, memory: WorkingMemory) -> None:
+        """Test basic set and get."""
+        await memory.set("key1", "value1")
+        result = await memory.get("key1")
+        assert result == "value1"
+
+    @pytest.mark.asyncio
+    async def test_get_with_default(self, memory: WorkingMemory) -> None:
+        """Test get with default value."""
+        result = await memory.get("nonexistent", default="fallback")
+        assert result == "fallback"
+
+    @pytest.mark.asyncio
+    async def test_delete(self, memory: WorkingMemory) -> None:
+        """Test delete operation."""
+        await memory.set("key1", "value1")
+        result = await memory.delete("key1")
+        assert result is True
+        assert await memory.exists("key1") is False
+
+    @pytest.mark.asyncio
+    async def test_exists(self, memory: WorkingMemory) -> None:
+        """Test exists check."""
+        await memory.set("key1", "value1")
+        assert await memory.exists("key1") is True
+        assert await memory.exists("nonexistent") is False
+
+    @pytest.mark.asyncio
+    async def test_reserved_key_prefix(self, memory: WorkingMemory) -> None:
+        """Test that keys starting with _ are rejected."""
+        with pytest.raises(ValueError, match="reserved"):
+            await memory.set("_internal", "value")
+
+    @pytest.mark.asyncio
+    async def test_cannot_delete_internal_keys(self, memory: WorkingMemory) -> None:
+        """Test that internal keys cannot be deleted directly."""
+        with pytest.raises(ValueError, match="internal"):
+            await memory.delete("_task_state")
+
+
+class TestWorkingMemoryListAndClear:
+    """Tests for list and clear operations."""
+
+    @pytest.mark.asyncio
+    async def test_list_keys(self, memory: WorkingMemory) -> None:
+        """Test listing keys."""
+        await memory.set("key1", "value1")
+        await memory.set("key2", "value2")
+
+        keys = await memory.list_keys()
+        assert set(keys) == {"key1", "key2"}
+
+    @pytest.mark.asyncio
+    async def test_list_keys_excludes_internal(self, memory: WorkingMemory) -> None:
+        """Test that list_keys excludes internal keys."""
+        await memory.set("user_key", "value")
+        # Internal keys exist from initialization
+        keys = await memory.list_keys()
+        assert all(not k.startswith("_") for k in keys)
+
+    @pytest.mark.asyncio
+    async def test_list_keys_with_pattern(self, memory: WorkingMemory) -> None:
+        """Test listing keys with pattern."""
+        await memory.set("prefix_a", "value1")
+        await memory.set("prefix_b", "value2")
+        await memory.set("other", "value3")
+
+        keys = await memory.list_keys("prefix_*")
+        assert set(keys) == {"prefix_a", "prefix_b"}
+
+    @pytest.mark.asyncio
+    async def test_get_all(self, memory: WorkingMemory) -> None:
+        """Test getting all key-value pairs."""
+        await memory.set("key1", "value1")
+        await memory.set("key2", "value2")
+
+        result = await memory.get_all()
+        assert result == {"key1": "value1", "key2": "value2"}
+
+    @pytest.mark.asyncio
+    async def test_clear_preserves_internal_state(self, memory: WorkingMemory) -> None:
+        """Test that clear preserves internal state."""
+        # Set some user data
+        await memory.set("user_key", "value")
+
+        # Set task state
+        state = TaskState(
+            task_id="task-1",
+            task_type="test",
+            description="Test task",
+        )
+        await memory.set_task_state(state)
+
+        # Clear
+        await memory.clear()
+
+        # User data should be gone
+        assert await memory.exists("user_key") is False
+
+        # Task state should be preserved
+        restored_state = await memory.get_task_state()
+        assert restored_state is not None
+        assert restored_state.task_id == "task-1"
+
+
+class TestWorkingMemoryTaskState:
+    """Tests for task state operations."""
+
+    @pytest.mark.asyncio
+    async def test_set_and_get_task_state(self, memory: WorkingMemory) -> None:
+        """Test setting and getting task state."""
+        state = TaskState(
+            task_id="task-123",
+            task_type="code_review",
+            description="Review pull request",
+            status="in_progress",
+            current_step=2,
+            total_steps=5,
+            progress_percent=40.0,
+            context={"pr_id": 456},
+        )
+
+        await memory.set_task_state(state)
+        result = await memory.get_task_state()
+
+        assert result is not None
+        assert result.task_id == "task-123"
+        assert result.task_type == "code_review"
+        assert result.status == "in_progress"
+        assert result.current_step == 2
+        assert result.progress_percent == 40.0
+        assert result.context == {"pr_id": 456}
+
+    @pytest.mark.asyncio
+    async def test_get_task_state_none_when_not_set(
+        self, memory: WorkingMemory
+    ) -> None:
+        """Test that get_task_state returns None when not set."""
+        result = await memory.get_task_state()
+        assert result is None
+
+    @pytest.mark.asyncio
+    async def test_update_task_progress(self, memory: WorkingMemory) -> None:
+        """Test updating task progress."""
+        state = TaskState(
+            task_id="task-123",
+            task_type="test",
+            description="Test",
+            current_step=1,
+            progress_percent=10.0,
+            status="running",
+        )
+        await memory.set_task_state(state)
+
+        updated = await memory.update_task_progress(
+            current_step=3,
+            progress_percent=60.0,
+            status="processing",
+        )
+
+        assert updated is not None
+        assert updated.current_step == 3
+        assert updated.progress_percent == 60.0
+        assert updated.status == "processing"
+
+    @pytest.mark.asyncio
+    async def test_update_task_progress_clamps_percent(
+        self, memory: WorkingMemory
+    ) -> None:
+        """Test that progress percent is clamped to 0-100."""
+        state = TaskState(
+            task_id="task-123",
+            task_type="test",
+            description="Test",
+        )
+        await memory.set_task_state(state)
+
+        updated = await memory.update_task_progress(progress_percent=150.0)
+        assert updated is not None
+        assert updated.progress_percent == 100.0
+
+        updated = await memory.update_task_progress(progress_percent=-10.0)
+        assert updated is not None
+        assert updated.progress_percent == 0.0
+
+
+class TestWorkingMemoryScratchpad:
+    """Tests for scratchpad operations."""
+
+    @pytest.mark.asyncio
+    async def test_append_and_get_scratchpad(self, memory: WorkingMemory) -> None:
+        """Test appending to and getting scratchpad."""
+        await memory.append_scratchpad("First note")
+        await memory.append_scratchpad("Second note")
+
+        entries = await memory.get_scratchpad()
+        assert entries == ["First note", "Second note"]
+
+    @pytest.mark.asyncio
+    async def test_get_scratchpad_empty(self, memory: WorkingMemory) -> None:
+        """Test getting empty scratchpad."""
+        entries = await memory.get_scratchpad()
+        assert entries == []
+
+    @pytest.mark.asyncio
+    async def test_get_scratchpad_with_timestamps(self, memory: WorkingMemory) -> None:
+        """Test getting scratchpad with timestamps."""
+        await memory.append_scratchpad("Test note")
+
+        entries = await memory.get_scratchpad_with_timestamps()
+        assert len(entries) == 1
+        assert entries[0]["content"] == "Test note"
+        assert "timestamp" in entries[0]
+
+    @pytest.mark.asyncio
+    async def test_clear_scratchpad(self, memory: WorkingMemory) -> None:
+        """Test clearing scratchpad."""
+        await memory.append_scratchpad("Note 1")
+        await memory.append_scratchpad("Note 2")
+
+        count = await memory.clear_scratchpad()
+        assert count == 2
+
+        entries = await memory.get_scratchpad()
+        assert entries == []
+
+
+class TestWorkingMemoryCheckpoints:
+    """Tests for checkpoint operations."""
+
+    @pytest.mark.asyncio
+    async def test_create_checkpoint(self, memory: WorkingMemory) -> None:
+        """Test creating a checkpoint."""
+        await memory.set("key1", "value1")
+        await memory.set("key2", "value2")
+
+        checkpoint_id = await memory.create_checkpoint("Test checkpoint")
+
+        assert checkpoint_id is not None
+        assert len(checkpoint_id) == 8  # UUID prefix
+
+    @pytest.mark.asyncio
+    async def test_restore_checkpoint(self, memory: WorkingMemory) -> None:
+        """Test restoring from a checkpoint."""
+        await memory.set("key1", "original")
+        checkpoint_id = await memory.create_checkpoint()
+
+        # Modify state
+        await memory.set("key1", "modified")
+        await memory.set("key2", "new")
+
+        # Restore
+        await memory.restore_checkpoint(checkpoint_id)
+
+        # Check restoration
+        assert await memory.get("key1") == "original"
+        # key2 didn't exist in checkpoint, so it should be gone
+        # But due to checkpoint being restored with clear, it's gone
+
+    @pytest.mark.asyncio
+    async def test_restore_nonexistent_checkpoint(self, memory: WorkingMemory) -> None:
+        """Test restoring from nonexistent checkpoint raises error."""
+        with pytest.raises(MemoryNotFoundError):
+            await memory.restore_checkpoint("nonexistent")
+
+    @pytest.mark.asyncio
+    async def test_list_checkpoints(self, memory: WorkingMemory) -> None:
+        """Test listing checkpoints."""
+        cp1 = await memory.create_checkpoint("First")
+        cp2 = await memory.create_checkpoint("Second")
+
+        checkpoints = await memory.list_checkpoints()
+
+        assert len(checkpoints) == 2
+        ids = [cp["id"] for cp in checkpoints]
+        assert cp1 in ids
+        assert cp2 in ids
+
+    @pytest.mark.asyncio
+    async def test_delete_checkpoint(self, memory: WorkingMemory) -> None:
+        """Test deleting a checkpoint."""
+        checkpoint_id = await memory.create_checkpoint()
+
+        result = await memory.delete_checkpoint(checkpoint_id)
+        assert result is True
+
+        checkpoints = await memory.list_checkpoints()
+        assert len(checkpoints) == 0
+
+
+class TestWorkingMemoryScope:
+    """Tests for scope handling."""
+
+    @pytest.mark.asyncio
+    async def test_scope_property(
+        self, memory: WorkingMemory, scope: ScopeContext
+    ) -> None:
+        """Test scope property."""
+        assert memory.scope == scope
+
+    @pytest.mark.asyncio
+    async def test_for_session_factory(self) -> None:
+        """Test for_session factory method."""
+        # This would normally try Redis and fall back to in-memory
+        # In tests, Redis won't be available, so it uses fallback
+        wm = await WorkingMemory.for_session(
+            session_id="session-abc",
+            project_id="project-123",
+            agent_instance_id="agent-456",
+        )
+
+        assert wm.scope.scope_type == ScopeLevel.SESSION
+        assert wm.scope.scope_id == "session-abc"
+        assert wm.scope.parent is not None
+        assert wm.scope.parent.scope_type == ScopeLevel.AGENT_INSTANCE
+
+
+class TestWorkingMemoryHealth:
+    """Tests for health and lifecycle."""
+
+    @pytest.mark.asyncio
+    async def test_is_healthy(self, memory: WorkingMemory) -> None:
+        """Test health check."""
+        assert await memory.is_healthy() is True
+
+    @pytest.mark.asyncio
+    async def test_get_stats(self, memory: WorkingMemory) -> None:
+        """Test getting stats."""
+        await memory.set("key1", "value1")
+        await memory.append_scratchpad("Note")
+
+        state = TaskState(task_id="t1", task_type="test", description="Test")
+        await memory.set_task_state(state)
+
+        stats = await memory.get_stats()
+
+        assert stats["scope_type"] == "session"
+        assert stats["scope_id"] == "test-session-123"
+        assert stats["user_keys"] == 1
+        assert stats["scratchpad_entries"] == 1
+        assert stats["has_task_state"] is True
+
+    @pytest.mark.asyncio
+    async def test_is_using_fallback(self, memory: WorkingMemory) -> None:
+        """Test fallback detection."""
+        # In-memory storage is always fallback
+        assert memory.is_using_fallback is False  # Not set in fixture
+
+    @pytest.mark.asyncio
+    async def test_close(self, memory: WorkingMemory) -> None:
+        """Test close doesn't error."""
+        await memory.close()  # Should not raise

backend/tests/unit/services/memory/working/test_storage.py

@@ -0,0 +1,303 @@
+# tests/unit/services/memory/working/test_storage.py
+"""Unit tests for working memory storage backends."""
+
+import asyncio
+
+import pytest
+
+from app.services.memory.exceptions import MemoryStorageError
+from app.services.memory.working.storage import InMemoryStorage
+
+
+class TestInMemoryStorageBasicOperations:
+    """Tests for basic InMemoryStorage operations."""
+
+    @pytest.fixture
+    def storage(self) -> InMemoryStorage:
+        """Create a fresh storage instance."""
+        return InMemoryStorage(max_keys=100)
+
+    @pytest.mark.asyncio
+    async def test_set_and_get(self, storage: InMemoryStorage) -> None:
+        """Test basic set and get."""
+        await storage.set("key1", "value1")
+        result = await storage.get("key1")
+        assert result == "value1"
+
+    @pytest.mark.asyncio
+    async def test_get_nonexistent_key(self, storage: InMemoryStorage) -> None:
+        """Test getting a key that doesn't exist."""
+        result = await storage.get("nonexistent")
+        assert result is None
+
+    @pytest.mark.asyncio
+    async def test_set_overwrites_existing(self, storage: InMemoryStorage) -> None:
+        """Test that set overwrites existing values."""
+        await storage.set("key1", "original")
+        await storage.set("key1", "updated")
+        result = await storage.get("key1")
+        assert result == "updated"
+
+    @pytest.mark.asyncio
+    async def test_delete_existing_key(self, storage: InMemoryStorage) -> None:
+        """Test deleting an existing key."""
+        await storage.set("key1", "value1")
+        result = await storage.delete("key1")
+        assert result is True
+        assert await storage.get("key1") is None
+
+    @pytest.mark.asyncio
+    async def test_delete_nonexistent_key(self, storage: InMemoryStorage) -> None:
+        """Test deleting a key that doesn't exist."""
+        result = await storage.delete("nonexistent")
+        assert result is False
+
+    @pytest.mark.asyncio
+    async def test_exists(self, storage: InMemoryStorage) -> None:
+        """Test exists check."""
+        await storage.set("key1", "value1")
+        assert await storage.exists("key1") is True
+        assert await storage.exists("nonexistent") is False
+
+
+class TestInMemoryStorageTTL:
+    """Tests for TTL functionality."""
+
+    @pytest.fixture
+    def storage(self) -> InMemoryStorage:
+        """Create a fresh storage instance."""
+        return InMemoryStorage(max_keys=100)
+
+    @pytest.mark.asyncio
+    async def test_set_with_ttl(self, storage: InMemoryStorage) -> None:
+        """Test that TTL is stored correctly."""
+        await storage.set("key1", "value1", ttl_seconds=10)
+        # Key should exist immediately
+        assert await storage.exists("key1") is True
+
+    @pytest.mark.asyncio
+    async def test_ttl_expiration(self, storage: InMemoryStorage) -> None:
+        """Test that expired keys return None."""
+        await storage.set("key1", "value1", ttl_seconds=1)
+
+        # Key exists initially
+        assert await storage.get("key1") == "value1"
+
+        # Wait for expiration
+        await asyncio.sleep(1.1)
+
+        # Key should be expired
+        assert await storage.get("key1") is None
+        assert await storage.exists("key1") is False
+
+    @pytest.mark.asyncio
+    async def test_remove_ttl_on_update(self, storage: InMemoryStorage) -> None:
+        """Test that updating without TTL removes expiration."""
+        await storage.set("key1", "value1", ttl_seconds=1)
+        await storage.set("key1", "value2")  # No TTL
+
+        await asyncio.sleep(1.1)
+
+        # Key should still exist (TTL removed)
+        assert await storage.get("key1") == "value2"
+
+
+class TestInMemoryStorageListAndClear:
+    """Tests for list and clear operations."""
+
+    @pytest.fixture
+    def storage(self) -> InMemoryStorage:
+        """Create a fresh storage instance."""
+        return InMemoryStorage(max_keys=100)
+
+    @pytest.mark.asyncio
+    async def test_list_keys_all(self, storage: InMemoryStorage) -> None:
+        """Test listing all keys."""
+        await storage.set("key1", "value1")
+        await storage.set("key2", "value2")
+        await storage.set("other", "value3")
+
+        keys = await storage.list_keys()
+        assert set(keys) == {"key1", "key2", "other"}
+
+    @pytest.mark.asyncio
+    async def test_list_keys_with_pattern(self, storage: InMemoryStorage) -> None:
+        """Test listing keys with pattern."""
+        await storage.set("key1", "value1")
+        await storage.set("key2", "value2")
+        await storage.set("other", "value3")
+
+        keys = await storage.list_keys("key*")
+        assert set(keys) == {"key1", "key2"}
+
+    @pytest.mark.asyncio
+    async def test_get_all(self, storage: InMemoryStorage) -> None:
+        """Test getting all key-value pairs."""
+        await storage.set("key1", "value1")
+        await storage.set("key2", "value2")
+
+        result = await storage.get_all()
+        assert result == {"key1": "value1", "key2": "value2"}
+
+    @pytest.mark.asyncio
+    async def test_clear(self, storage: InMemoryStorage) -> None:
+        """Test clearing all keys."""
+        await storage.set("key1", "value1")
+        await storage.set("key2", "value2")
+
+        count = await storage.clear()
+        assert count == 2
+        assert await storage.get_all() == {}
+
+
+class TestInMemoryStorageCapacity:
+    """Tests for capacity limits."""
+
+    @pytest.mark.asyncio
+    async def test_capacity_limit_exceeded(self) -> None:
+        """Test that exceeding capacity raises error."""
+        storage = InMemoryStorage(max_keys=2)
+
+        await storage.set("key1", "value1")
+        await storage.set("key2", "value2")
+
+        with pytest.raises(MemoryStorageError, match="capacity exceeded"):
+            await storage.set("key3", "value3")
+
+    @pytest.mark.asyncio
+    async def test_update_existing_key_within_capacity(self) -> None:
+        """Test that updating existing key doesn't count against capacity."""
+        storage = InMemoryStorage(max_keys=2)
+
+        await storage.set("key1", "value1")
+        await storage.set("key2", "value2")
+        await storage.set("key1", "updated")  # Should succeed
+
+        assert await storage.get("key1") == "updated"
+
+    @pytest.mark.asyncio
+    async def test_expired_keys_freed_for_capacity(self) -> None:
+        """Test that expired keys are cleaned up for capacity."""
+        storage = InMemoryStorage(max_keys=2)
+
+        await storage.set("key1", "value1", ttl_seconds=1)
+        await storage.set("key2", "value2")
+
+        await asyncio.sleep(1.1)
+
+        # Should succeed because key1 is expired and will be cleaned
+        await storage.set("key3", "value3")
+        assert await storage.get("key3") == "value3"
+
+
+class TestInMemoryStorageDataTypes:
+    """Tests for different data types."""
+
+    @pytest.fixture
+    def storage(self) -> InMemoryStorage:
+        """Create a fresh storage instance."""
+        return InMemoryStorage(max_keys=100)
+
+    @pytest.mark.asyncio
+    async def test_store_dict(self, storage: InMemoryStorage) -> None:
+        """Test storing dict values."""
+        data = {"nested": {"key": "value"}, "list": [1, 2, 3]}
+        await storage.set("dict_key", data)
+        result = await storage.get("dict_key")
+        assert result == data
+
+    @pytest.mark.asyncio
+    async def test_store_list(self, storage: InMemoryStorage) -> None:
+        """Test storing list values."""
+        data = [1, 2, {"nested": "dict"}]
+        await storage.set("list_key", data)
+        result = await storage.get("list_key")
+        assert result == data
+
+    @pytest.mark.asyncio
+    async def test_store_numbers(self, storage: InMemoryStorage) -> None:
+        """Test storing numeric values."""
+        await storage.set("int_key", 42)
+        await storage.set("float_key", 3.14)
+
+        assert await storage.get("int_key") == 42
+        assert await storage.get("float_key") == 3.14
+
+    @pytest.mark.asyncio
+    async def test_store_boolean(self, storage: InMemoryStorage) -> None:
+        """Test storing boolean values."""
+        await storage.set("true_key", True)
+        await storage.set("false_key", False)
+
+        assert await storage.get("true_key") is True
+        assert await storage.get("false_key") is False
+
+    @pytest.mark.asyncio
+    async def test_store_none(self, storage: InMemoryStorage) -> None:
+        """Test storing None value."""
+        await storage.set("none_key", None)
+        # Note: None is stored, but get returns None for both missing and None values
+        # Use exists to distinguish
+        assert await storage.exists("none_key") is True
+
+
+class TestInMemoryStorageHealth:
+    """Tests for health and lifecycle."""
+
+    @pytest.mark.asyncio
+    async def test_is_healthy(self) -> None:
+        """Test health check."""
+        storage = InMemoryStorage()
+        assert await storage.is_healthy() is True
+
+    @pytest.mark.asyncio
+    async def test_close(self) -> None:
+        """Test close is no-op but doesn't error."""
+        storage = InMemoryStorage()
+        await storage.close()  # Should not raise
+
+
+class TestInMemoryStorageConcurrency:
+    """Tests for concurrent access."""
+
+    @pytest.mark.asyncio
+    async def test_concurrent_writes(self) -> None:
+        """Test concurrent write operations don't corrupt data."""
+        storage = InMemoryStorage(max_keys=1000)
+
+        async def write_batch(prefix: str, count: int) -> None:
+            for i in range(count):
+                await storage.set(f"{prefix}_{i}", f"value_{i}")
+
+        # Run concurrent writes
+        await asyncio.gather(
+            write_batch("a", 100),
+            write_batch("b", 100),
+            write_batch("c", 100),
+        )
+
+        # Verify all writes succeeded
+        keys = await storage.list_keys()
+        assert len(keys) == 300
+
+    @pytest.mark.asyncio
+    async def test_concurrent_read_write(self) -> None:
+        """Test concurrent read and write operations."""
+        storage = InMemoryStorage()
+        await storage.set("key", 0)
+
+        async def increment() -> None:
+            for _ in range(100):
+                val = await storage.get("key") or 0
+                await storage.set("key", val + 1)
+
+        # Run concurrent increments
+        await asyncio.gather(
+            increment(),
+            increment(),
+        )
+
+        # Final value depends on interleaving
+        # Just verify we don't crash and value is positive
+        result = await storage.get("key")
+        assert result > 0