/api/send reports Relaycast publication as success without recipient reachability

[khaliqgant]

Summary

For a Relaycast-backed direct send, the broker returns:

{"success":true,"relaycast_published":true,"local":false}

when Relaycast accepted the message even if the target agent row has no live holder and cannot receive it. Publication is durable acceptance, not delivery. This hid the orphaned-name failure measured in AgentWorkforce/relaycast#359.

Attribution

The misleading response is constructed in crates/broker/src/runtime/api.rs:

• selected_workspace.http_client.send_with_mode(...) returns Result<()>;
• on Ok(()), the broker unconditionally writes relaycast_published: true and no reachability/delivery field.

The information is also discarded one layer earlier: crates/broker/src/relaycast/ws.rs::send_dm_with_mode awaits the Rust SDK AgentClient::dm(...) response and then returns Ok(()).

Relay currently cannot honestly claim delivery from that response. Relaycast's POST /v1/dm creates a durable delivery row, but its public response strips the internal delivery record and dispatch happens in background. A complete delivery receipt therefore needs an upstream Relaycast contract addition; this broker must propagate it once available.

Small, independently useful relay fix

For a named DM target, return an explicit server-observed reachability snapshot even before the richer receipt exists:

{
  "success": true,
  "relaycast_published": true,
  "delivery_status": "published_unconfirmed",
  "recipient_live": false,
  "recipient_status": "offline"
}

Use Relaycast's target-agent read/presence result; do not infer life from the broker's local PTY map. If the probe is unavailable, report recipient_live: null / recipient_status: "unknown" rather than failing an already-published send or claiming success. Channel targets should likewise report delivery as unconfirmed, without inventing one boolean for multiple recipients.

This is intentionally not delivered: false: an offline recipient may later drain its durable mailbox. It says only what is known at response time — publication succeeded and no live holder was observed.

Verification

• Must fire: Relaycast accepts a DM while the target read reports offline; /api/send remains a 200 publication success but returns delivery_status: published_unconfirmed, recipient_live: false, and recipient_status: offline.
• Must not fire: a target read failure must not be rendered as recipient_live: true; it returns unknown.
• A live target returns recipient_live: true but still does not claim delivered until Relaycast supplies a delivery receipt.
• Update Broker SDK response types so the fields survive decoding.

Related: AgentWorkforce/relaycast#359. Follow-up upstream work should expose the durable delivery id/current status from POST /v1/dm so relay can replace the reachability snapshot with an actual receipt.