Module progress 

ProgressSink implementation that publishes MCP notifications/progress JSON-RPC messages onto a per-request channel. The HTTP handler wires the receiver end into an SSE stream that ships events back to the client.

Shape of the emitted JSON-RPC message follows the MCP spec:

{
  "jsonrpc": "2.0",
  "method": "notifications/progress",
  "params": {
    "progressToken": <u64>,
    "progress": <u64>,
    "total": <u64 | null>,
    "message": "<optional string>"
  }
}

Dual-fanout (M4)

In addition to the per-request SSE channel, McpProgressSink can also publish a ProgressEvent onto the session’s shared broadcast channel (see session::SessionState::events). That second fanout is what feeds the V2 Code tab’s inline status-card strip: the external CLI drives the request, but the Construct UI reads the same events via the session-wide stream regardless of who is talking to the daemon.

Broadcast send errors (no live receivers) are intentionally ignored — progress events are advisory and must never block a tool invocation.

Structs

McpProgressSink

Sink used for a single in-flight tools/call JSON-RPC request.