EXPERIMENTAL_BACKGROUND_SUBAGENTS: hidden sessions created inside ephemeral subagent processes can never be deleted at runtime (owner is undefined, the DELETE is never even attempted) #594

Short description

With OPENCODE_EXPERIMENTAL_BACKGROUND_SUBAGENTS=true, OpenCode 2 spawns short-lived opencode processes for background subagents. These processes load Magic Context like any other opencode process. Hidden sessions created by the plugin running inside them record no owner, so they can never be deleted at runtime — by design of the owner-bound route, not by any transient failure.

What happened?

Every opencode process loads the configured plugins — we observed plugin boot logs from short-lived app: "cli" processes spawned for background subagents (four boots within one second during a batch). When the plugin inside such a process creates a hidden child:

1. hostServiceOwner() only returns a value when the creating process registered a service. Ephemeral subagent processes never register, so child.owner is undefined.
2. On retire, resolveOwnerHostService(undefined) throws HostServiceUnavailable ("created by an OpenCode host that registered no service, so there is no owner-bound route to delete it through") before any HTTP request is made.
3. The failure is caught and logged as "left for a later sweep" — but the sweep hits the same gate, so runtime retries can never succeed. The plugin's own output says the only cleanup is doctor --fix with OpenCode closed.

Supporting observation: an ephemeral process booted at 01:33:47 observed the parent session idle at 01:34:24.524, and a batch of dreamer hidden sessions was created at 01:34:24.558 (34 ms later) — consistent with the plugin in the ephemeral process firing the due dream run.

Structurally, the creating process is gone by the time anyone could retry, so no owner-bound route can ever exist for these children — even on hosts where deletion otherwise works (e.g. OpenChamber attached to a registered service instance). This lane leaks one visible root session per hidden run until an offline doctor --fix pass, and on plain-serve hosts it adds to the pile from #589.

Suggestion

On retire, if the current process created the child and no owner-bound service route exists, attempt the delete while the process is still alive, through its own credentials: process.env.OPENCODE_PASSWORD (or the legacy OPENCODE_SERVER_PASSWORD) plus the hostname/port from process.argv (serve --hostname <h> --port <p>). Hosts that inject the password (OpenChamber does — it sets OPENCODE_PASSWORD on the managed instance) would then clean up at retire time. That same fallback also fixes the plain-serve case in #589. The fully general fix remains an in-process session remove in the plugin host API (anomalyco/opencode#49389).

Diagnostics

• Affected children have no owner recorded; retirement logs "cannot be deleted: no owner-bound host removal route; run doctor --fix with OpenCode closed".
• Code path: hostServiceOwner() → child.owner → resolveOwnerHostService gate (a) → throw before HTTP.

Plugin version

0.44.4 (dist analysis)

OpenCode version

2.0.18

Platform

linux x64

Client

OpenChamber 2.0.4 (web) against opencode serve; OPENCODE_EXPERIMENTAL_BACKGROUND_SUBAGENTS=true