Subagent permission/error events leave external integrations no way to see root-session progress (pane misreported as blocked/needs-input while subagent runs)

Description

Child-session events (permission.asked, question.asked, session.error) are broadcast on the global event bus with only the child's sessionID and parentID in the payload, while the parent session's own status keeps reporting busy (or goes silent) for the whole duration of a subagent run. External consumers therefore cannot distinguish "a subagent inside this root session hit a transient stream error / a rule-evaluated permission that resolves itself" from "this root session is actually waiting on the user", and there is no reliable signal on the root session telling them the subagent recovered or finished.

Concretely: the herdr integration plugin (installed via herdr integration install opencode) maps child-session permission.asked / question.asked / session.error to blocked for the pane. When a subagent starts and later hits a transient stream error (which opencode auto-retries), the pane goes red "blocked" and plays the notification sound, even though:

• the screen shows no permission/error UI at all (the subagent is streaming and editing files normally), and
• the root session status never reflected anything but busy.

Observed on a real run: while a code-writer subagent ran for ~15 minutes, the pane stayed blocked the whole time with zero state changes, while opencode's log showed continuous subagent streaming (mode=subagent) and file edits; herdr agent explain --json reported visible_blocker: false. The same session's log later showed AI_APICallError: Cannot connect to API ... socket connection was closed unexpectedly on the subagent session, which matches the plugin's blocked trigger.

A controlled capture of the SSE event bus (GET /event) while a subagent ran shows the gap directly:

session.status  ROOT {type: busy}          <- last root event before the subagent starts
session.created SUB ses_... (parentID set)
session.status  SUB  {type: busy}  xN
session.status  SUB  {type: idle}
session.idle    SUB
session.status  ROOT {type: busy}          <- root only updates again after the subagent finished

No permission.* events were emitted for an auto-allowed call, and no root-session event marks "a subagent of mine started / is running / failed transiently / recovered".

Request: surface subagent lifecycle on the root session (e.g. root-visible session.status reflecting child progress, or task.* / child-session state events that integrations can use), so external integrations can avoid rendering a running subagent (or its auto-recovering stream errors) as "waiting for user input".

Plugins

herdr-agent-state.js (installed by herdr integration install opencode, v10) — its behavior is the symptom, but the underlying issue is on the opencode event model side: child-session session.error reaches plugins with no root-session context and no follow-up "recovered" event on the root session.

OpenCode version

1.18.25

Steps to reproduce

1. Install the herdr integration for opencode (herdr integration install opencode) and run opencode inside herdr (any opencode ≥1.18 with plugins).
2. Prompt the agent to dispatch a subagent that runs a few minutes (e.g. a code-writer subagent editing several files), or let a subagent hit a transient API stream error (it auto-retries).
3. While the subagent runs normally (or during its automatic retry), the herdr pane shows red blocked and plays the notification sound; no approval or error UI is visible in the TUI. herdr agent explain <pane> --json shows state blocked with visible_blocker: false.
4. Equivalent without herdr: capture GET /event on the opencode server while dispatching a subagent (see event sequence above) — the root session emits nothing between subagent start and completion, while child session.status/session.error events appear with only the child sessionID.

Screenshot and/or share link

Not applicable (state observed via herdr agent list / herdr agent explain; can provide on request).

Operating System

macOS 26.6 arm64

Terminal

Ghostty 1.3.1