fix(graph): use SDK in-process ASGI transport for thread metadata writes

[blove]

Root cause (diagnosed via PR #492's @Traceable wrapper)

{
  "error_type": "ConnectError",
  "error_message": "All connection attempts failed",
  "sdk_url": "http://localhost:2024",
  "thread_id": "019e4768-143b-7f73-8da2-55c9657d478d"
}

The Python helper was calling get_client(url='http://localhost:2024') whenever LANGGRAPH_API_URL was unset, then HTTP-calling back into the runtime. In local dev this accidentally works because langgraph dev listens on 2024. On the prod runtime container the server is on a different port — every title write threw ConnectError, the bare except swallowed it, every prod thread showed "Untitled."

Fix

Pass url=os.environ.get("LANGGRAPH_API_URL") (no fallback). When None, the SDK uses its in-process ASGI transport — the canonical path for graph-to-server self-calls. From the SDK docstring:

If None, the client first attempts an in-process connection via ASGI transport. ... This only works if the client is used from within the Agent server.

Applies to:

• examples/chat/python (the demo where the bug surfaced)
• cockpit/chat/threads/python (same anti-pattern; would've failed on prod for the same reason)

Verification

PR #492's @traceable instrumentation stays. After merge + deploy, a probe should produce a LangSmith run with outputs.wrote_title: "<title slice>" instead of the ConnectError.

Test plan

• Both graphs compile + import (from src.graph import graph)
• CI green
• After merge + deploy: probe → LangSmith run shows wrote_title, /api/threads/<id>.metadata.title populated, sidenav row shows the title (not "Untitled")
• If the verification probe still fails, the @Traceable output will tell us what changed

Trail

• debug(langgraph): add console.debug to LangGraphThreadsAdapter.refresh() #486 — frontend debug logs (proved refresh works)
• debug(graph): surface _maybe_write_thread_title failures #491 — Python print() logs (couldn't see them via API)
• debug(graph): @traceable _maybe_write_thread_title so LangSmith captures errors #492 — @Traceable wrapper (surfaced ConnectError + sdk_url)
• fix(graph): use SDK in-process ASGI transport for thread metadata writes #493 (this PR) — root-cause fix

🤖 Generated with Claude Code

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Project	Deployment	Actions	Updated (UTC)
threadplane	Ready	Preview, Comment	May 20, 2026 10:09pm