[Deep Agent] Remove process-global request state (capability flags, connection singleton, frozen date) via runtime context #38

Problem

The deep agent keeps request-scoped data in process-global mutable state. That is unsafe as soon as more than one user, connection, or concurrent request hits the same process:

• _connection_capabilities (agent/src/deep_agent/tools.py:20) is a module-level dict that get_database_catalog mutates. If connection A's catalog has no knowledge pairs, then for every other user/connection in the process, search_knowledge_pairs returns "[] ... Do not call this tool again" until someone else's catalog call flips it back. Under concurrency this is a race. The flags also start as True, so behaviour depends on call order.
• The connection is selected by mutating a singleton: run_deep_agent.py:207-209 sets os.environ[...] and the private client._connection_id. No tool accepts a connection, so the deep agent cannot serve two connections in one process at all.
• today is formatted into the system prompt once, at agent construction (agent.py:239). A long-running server will report a stale date after midnight. That affects every relative-date question ("אתמול", "השבוע").

Proposed fix

• Define a context_schema (LangGraph runtime context), e.g. DeepAgentContext(connection_id: int, user_id: str, locale: str = "he"), and pass it per invocation (agent.ainvoke(..., context=DeepAgentContext(...))).
• Tools read the connection via ToolRuntime[DeepAgentContext] and call JeenMetadataClient methods with an explicit connection_id (most already accept connection_id=).
• Store capability flags in graph state (returned via Command(update=...) from get_database_catalog), or compute them per connection in a cache keyed by connection_id.
• Inject today's date dynamically with a @dynamic_prompt / before_model middleware (timezone Asia/Jerusalem), not at construction time.

Acceptance Criteria

• No module-level mutable request state remains in agent/src/deep_agent/.
• Two concurrent ainvoke calls with different connection_ids (one with knowledge pairs, one without) produce correct, independent tool behaviour. Covered by an asyncio test.
• run_deep_agent.py no longer touches client._connection_id or os.environ to switch connections.
• The date in the prompt reflects the day of the invocation in Asia/Jerusalem (test with a frozen clock across midnight).

Definition of Done

• Concurrency test added and green.
• Tool docstrings unchanged from the model's point of view (context is injected, not a model argument).
• Merged.

Open questions

• Is connection_id chosen by the user in the UI (see PR added option to choose connection by name from jeen metadata #31, "choose connection by name"), or by routing? That determines whether it belongs in context or state.

Found in an architecture/code review of feature/deep-agent-updated (commits 5cc8398, 897de37, b8e27c8) vs main.

🤖 Generated with Claude Code