Plugin Chat: Streaming Implementation Plan

Goal

Make the chat plugin work with real-time SSE streaming instead of polling. The backend infrastructure is 100% complete — we need frontend bridge code and plugin updates.

What Exists (Done)

Layer	Status	Location
SSE route	Done	server/src/routes/plugins.ts — GET /api/plugins/:pluginId/bridge/stream/:channel?companyId=X
Stream bus	Done	server/src/services/plugin-stream-bus.ts — in-memory pub/sub with subscribe()/publish()
Worker RPC	Done	sdk/src/protocol.ts — streams.open, streams.emit, streams.close JSON-RPC notifications
Worker context	Done	sdk/src/worker-rpc-host.ts — ctx.streams.open/emit/close methods
Worker manager	Done	server/src/services/plugin-worker-manager.ts — forwards notifications to stream bus, crash cleanup
SDK types	Done	sdk/src/ui/types.ts — PluginStreamResult<T> interface
SDK hook declaration	Done	sdk/src/ui/hooks.ts — usePluginStream<T>(channel, options?)

What's Missing (To Build)

1. usePluginStream() concrete implementation in ui/src/plugins/bridge.ts

Opens an EventSource to the SSE endpoint, accumulates events, tracks connection state.

2. Register usePluginStream in ui/src/plugins/bridge-init.ts

Add it to the sdkUi object in initPluginBridge().

3. Update plugin worker to emit stream events

In sendMessage action, call ctx.streams.emit() inside the onEvent callback to push events to the UI in real-time.

4. Update plugin UI to consume stream events

Replace polling with usePluginStream() for live token-by-token updates.

Code Changes

See the corresponding commits for the implementation.