feat: implement agent caches and fix invalid prompt cache configs

- Added a new function `_warm_agent_jit_caches` to pre-warm agent caches at startup, reducing cold invocation costs.
- Updated the `SurfSenseContextSchema` to include per-invocation fields for better state management during agent execution.
- Introduced caching mechanisms in various tools to ensure fresh database sessions are used, improving performance and reliability.
- Enhanced middleware to support new context features and improve error handling during connector and document type discovery.

surfsense_backend/app/agents/new_chat/context.py

@@ -1,10 +1,25 @@
 """
 Context schema definitions for SurfSense agents.
 
-This module defines the custom state schema used by the SurfSense deep agent.
+This module defines the per-invocation context object passed to the SurfSense
+deep agent via ``agent.astream_events(..., context=ctx)`` (LangGraph >= 0.6).
+
+The agent's compiled graph is the same across invocations (and cached by
+``agent_cache``), so anything that varies per turn — the user mentions a
+specific document, the front-end issues a unique ``request_id``, etc. —
+MUST live on this context object instead of being captured into a
+middleware ``__init__`` closure. Middlewares read fields back via
+``runtime.context.<field>``; tools read them via ``runtime.context``.
+
+This object is read inside both ``KnowledgePriorityMiddleware`` (for
+``mentioned_document_ids``) and any future middleware that needs
+per-request state without invalidating the compiled-agent cache.
 """
 
-from typing import NotRequired, TypedDict
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+from typing import TypedDict
 
 
 class FileOperationContractState(TypedDict):
@@ -15,25 +30,35 @@ class FileOperationContractState(TypedDict):
     turn_id: str
 
 
-class SurfSenseContextSchema(TypedDict):
+@dataclass
+class SurfSenseContextSchema:
     """
-    Custom state schema for the SurfSense deep agent.
+    Per-invocation context for the SurfSense deep agent.
 
-    This extends the default agent state with custom fields.
-    The default state already includes:
-    - messages: Conversation history
-    - todos: Task list from TodoListMiddleware
-    - files: Virtual filesystem from FilesystemMiddleware
+    Defaults are chosen so the dataclass can be safely default-constructed
+    (LangGraph's ``Runtime.context`` itself defaults to ``None`` if no
+    context is supplied — see ``langgraph.runtime.Runtime``). All fields
+    are optional; consumers must None-check before reading.
 
-    We're adding fields needed for knowledge base search:
-    - search_space_id: The user's search space ID
-    - db_session: Database session (injected at runtime)
-    - connector_service: Connector service instance (injected at runtime)
+    Phase 1.5 fields:
+        search_space_id: Search space the request is scoped to.
+        mentioned_document_ids: KB documents the user @-mentioned this turn.
+            Read by ``KnowledgePriorityMiddleware`` to seed its priority
+            list. Stays out of the compiled-agent cache key — that's the
+            whole point of putting it here.
+        file_operation_contract: One-shot file operation contract emitted
+            by ``FileIntentMiddleware`` for the upcoming turn.
+        turn_id / request_id: Correlation IDs surfaced by the streaming
+            task; populated for telemetry.
+
+    Phase 2 will extend with: thread_id, user_id, visibility,
+    filesystem_mode, anon_session_id, available_connectors,
+    available_document_types, created_by_id (everything currently captured
+    by middleware ``__init__`` closures).
     """
 
-    search_space_id: int
-    file_operation_contract: NotRequired[FileOperationContractState]
-    turn_id: NotRequired[str]
-    request_id: NotRequired[str]
-    # These are runtime-injected and won't be serialized
-    # db_session and connector_service are passed when invoking the agent
+    search_space_id: int | None = None
+    mentioned_document_ids: list[int] = field(default_factory=list)
+    file_operation_contract: FileOperationContractState | None = None
+    turn_id: str | None = None
+    request_id: str | None = None