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fix(c-generative-ui): emit_state → get_stream_writer (LangGraph 1.x) #360

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Merged
blove merged 1 commit into from
May 16, 2026
Merged

fix(c-generative-ui): emit_state → get_stream_writer (LangGraph 1.x) #360

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16 changes: 13 additions & 3 deletions cockpit/chat/generative-ui/python/src/graph.py
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Original file line number Diff line number Diff line change
Expand Up @@ -67,8 +67,13 @@ def should_call_tools(state: DashboardState) -> Literal["call_tools", "respond"]


async def emit_state(state: DashboardState) -> DashboardState:
"""Emit state_update custom events from tool results."""
from langchain_core.callbacks import adispatch_custom_event
"""Emit state_update custom events from tool results.

Uses LangGraph 1.x's `get_stream_writer()` — `adispatch_custom_event`
no longer flows into the `custom` stream channel. The chat-lib bridge
parses the payload as `{name: 'state_update', data: <patches>}`.
"""
from langgraph.config import get_stream_writer

tool_results = {}
for msg in reversed(state["messages"]):
Expand All @@ -93,7 +98,12 @@ async def emit_state(state: DashboardState) -> DashboardState:
break

if tool_results:
await adispatch_custom_event("state_update", {"updates": tool_results})
# The chat-lib bridge (stream-manager.bridge.ts handles the 'custom'
# case) parses `eventData['name']` for routing and `eventData['data']`
# for payload; chat.component.ts then forwards data to
# signal-state-store.update() which expects flat Record<jsonPointer, value>.
writer = get_stream_writer()
writer({"name": "state_update", "data": tool_results})

return state

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16 changes: 13 additions & 3 deletions cockpit/langgraph/streaming/python/src/dashboard_graph.py
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Original file line number Diff line number Diff line change
Expand Up @@ -67,8 +67,13 @@ def should_call_tools(state: DashboardState) -> Literal["call_tools", "respond"]


async def emit_state(state: DashboardState) -> DashboardState:
"""Emit state_update custom events from tool results."""
from langchain_core.callbacks import adispatch_custom_event
"""Emit state_update custom events from tool results.

Uses LangGraph 1.x's `get_stream_writer()` — `adispatch_custom_event`
no longer flows into the `custom` stream channel. The chat-lib bridge
parses the payload as `{name: 'state_update', data: <patches>}`.
"""
from langgraph.config import get_stream_writer

tool_results = {}
for msg in reversed(state["messages"]):
Expand All @@ -94,7 +99,12 @@ async def emit_state(state: DashboardState) -> DashboardState:
break

if tool_results:
await adispatch_custom_event("state_update", {"updates": tool_results})
# The chat-lib bridge (stream-manager.bridge.ts handles the 'custom'
# case) parses `eventData['name']` for routing and `eventData['data']`
# for payload; chat.component.ts then forwards data to
# signal-state-store.update() which expects flat Record<jsonPointer, value>.
writer = get_stream_writer()
writer({"name": "state_update", "data": tool_results})

return state

Expand Down
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