fix: native Python agent for Render deployment

[GeneralJerel]

Summary

• Replace langchain/langgraph-api Docker image with native FastAPI + ag_ui_langgraph server, eliminating the PostgreSQL dependency that blocked Render deployment
• Add BoundedMemorySaver (200 thread cap, FIFO eviction) for memory-safe checkpointing on Render's 512MB starter plan
• Switch frontend from LangGraphAgent to LangGraphHttpAgent (AG-UI protocol)
• Add Three.js coordinate conventions to fix consistent aircraft axis swap in 3D visualizations

Test plan

• Agent starts and /health returns {"status":"ok"}
• Frontend connects and chat works end-to-end
• Render deploys agent as native Python (no Docker)
• Render health check passes on /health

🤖 Generated with Claude Code

[GeneralJerel]

PR Review

Overview

Solid PR. Replaces the langgraph-api Docker image (which required PostgreSQL) with a native FastAPI server, unblocking Render deployment. Net -134 lines — nice cleanup.

Findings

1. BoundedMemorySaver.put() — eviction loop can desync (Medium)

apps/agent/src/bounded_memory_saver.py:46-54 — If a thread is evicted from _insertion_order but was already deleted from self.storage by some other path, the while loop pops from _insertion_order without actually shrinking self.storage, potentially looping until _insertion_order is empty. The if oldest_thread in self.storage guard skips the delete but doesn't re-check the loop condition against the right collection.

Consider adding a secondary guard:

while len(self.storage) > self.max_threads and self._insertion_order:

2. warnings.filterwarnings placement (Low)

apps/agent/main.py:98 — The pydantic warning filter is set after add_langgraph_fastapi_endpoint and agent creation, which is where most pydantic warnings fire (during model validation at import/construction time). Move it before agent = create_deep_agent(...) to actually suppress those warnings.

3. render.yaml — LANGGRAPH_DEPLOYMENT_URL uses hostport (Low, verify)

render.yaml:48-51 — The frontend normalizes bare host:port into http:// at route.ts:40-44, which is good. Just confirm Render's internal service communication is plain HTTP (not HTTPS) — if Render uses TLS between services, this would need https://.

4. Dockerfile.agent deleted but .env.example not updated (Nit)

The Dockerfile is removed — if .env.example or README referenced Docker-based setup for the agent, those docs may be stale. Worth a quick check.

What looks good

• Clean separation: FastAPI app setup is straightforward
• BoundedMemorySaver concept is well-reasoned for the 512MB constraint, with good docstring noting the MemorySaver.storage internal dependency and version pin
• Frontend LangGraphAgent → LangGraphHttpAgent switch is correct for AG-UI protocol
• Dependency cleanup removes ~25 packages (langgraph-api, langgraph-cli, etc.)
• Health check endpoint enables Render's health monitoring
• Three.js coordinate convention docs are clear and well-structured

Verdict

Ship it with the while loop guard fix (finding #1). The rest are minor.