fix(subagent): report resumable children as ready

list_agents called a storage-only continuable child 'complete', inviting
parents to poll it for a result that will never appear there. Rename the
status to 'ready' — resumable, not terminal — and rewrite the tool
description to say a parent is told when a child finishes, so listing is
for recall, not polling.

packages/subagent/tool-subagent-control/README.md

@@ -8,7 +8,7 @@ The tool performs no lifecycle routing — residency and cold resume belong to t
 
 `interrupt_agent(agent_id)` passes `exec.agent` as the exact live ancestor authority for `ctx.subagents.interrupt()`: the target may be a direct child or a deeper descendant, and the service — never this tool — verifies the caller against the target Activation's recorded lineage. Only the target's current turn stops (`keepInbox`): queued messages stay parked until a later `send_message`, published descendants keep running, and the child stays available for follow-ups. The call returns as soon as the stop request is accepted, without waiting for target quiescence; an absent or already-settled target is an accepted no-op, while self, sibling, stale, and non-ancestor callers become errored results.
 
-`list_agents` takes one optional `scope` argument, derives the root id from the calling agent, and projects the service catalog to continuable children without a cursor. The default `children` scope reads `ctx.subagents.listChildren()`; `descendants` reads `ctx.subagents.listDescendants()`, whose one-corpus walk crosses ordinary sessions and one-shot children and renders surviving rows in stable pre-order with `parent=<id> depth=<n>`. The `parent` annotation is the durable direct-parent session id and may name an ordinary session omitted from the output. For the calling agent, only depth-1 child entries are `send_message` candidates; deeper child entries are `interrupt_agent` candidates only. Status comes from the live Agent registry: `running` (active driver), `idle` (resident between turns, possibly waiting on agents it started), `complete` (storage only). The service result also contains one-shot session-backed subagents for consumers such as a UI, but those entries are omitted from this model tool because they cannot accept `send_message`. Diagnostics remain visible, with positions in the descendants scope. Durable identity and mode come from each child's descriptor, while delivery-time authority and Activation ownership checks remain the service's.
+`list_agents` takes one optional `scope` argument, derives the root id from the calling agent, and projects the service catalog to continuable children without a cursor. The default `children` scope reads `ctx.subagents.listChildren()`; `descendants` reads `ctx.subagents.listDescendants()`, whose one-corpus walk crosses ordinary sessions and one-shot children and renders surviving rows in stable pre-order with `parent=<id> depth=<n>`. The `parent` annotation is the durable direct-parent session id and may name an ordinary session omitted from the output. For the calling agent, only depth-1 child entries are `send_message` candidates; deeper child entries are `interrupt_agent` candidates only. Status comes from the live Agent registry: `running` (active driver), `idle` (resident between turns, possibly waiting on agents it started), or `ready` (storage only and resumable rather than terminal). The service result also contains one-shot session-backed subagents for consumers such as a UI, but those entries are omitted from this model tool because they cannot accept `send_message`. Diagnostics remain visible, with positions in the descendants scope. Durable identity and mode come from each child's descriptor, while delivery-time authority and Activation ownership checks remain the service's.
 
 ## Model Experience
 
@@ -58,7 +58,7 @@ Append-only; newly visible content follows the reusable request prefix and does
 
 #### What the model sees
 
-One line per continuable child in stable catalog order: `<id> [<status>] — <label>` (`running` = active driver, `idle` = resident between turns, `complete` = storage only; a direct child in that state can be resumed by `send_message`), plus `<id> [diagnostic: <reason>]` for a candidate that could not be read (`corrupt`, `unsupported`, or `unavailable`). The `descendants` scope inserts ` parent=<id> depth=<n>` before the label dash on every line, in pre-order. One-shot children are intentionally absent; `(no subagents)` means no continuable child or diagnostic survived the projection. Diagnostics never expose descriptor contents.
+One line per continuable child in stable catalog order: `<id> [<status>] — <label>` (`running` = active driver, `idle` = resident between turns, `ready` = storage only; resumable rather than terminal, not a result waiting to be collected — a direct child in that state can be resumed by `send_message`), plus `<id> [diagnostic: <reason>]` for a candidate that could not be read (`corrupt`, `unsupported`, or `unavailable`). The `descendants` scope inserts ` parent=<id> depth=<n>` before the label dash on every line, in pre-order. One-shot children are intentionally absent; `(no subagents)` means no continuable child or diagnostic survived the projection. Diagnostics never expose descriptor contents.
 
 #### Token effect
 
@@ -72,5 +72,5 @@ Append-only; each result follows the reusable request prefix.
 
 - **A queued message has no independent result** — acceptance returns only its inbox `messageId`; the child's work lands in the durable child Session and is never collected through this tool. A child granted `report` may send selected content back separately, but that message is not this call's result.
 - **No steering of the current turn** — every message opens a later FIFO turn, so a message sent while the child is working runs only after its current turn finishes and cannot redirect it.
-- **Listing is a snapshot, not a delivery promise** — it may race publication, disposal, or a later message, and another process may activate a child this process reports as `complete`; cross-process accuracy requires a shared lease. `interrupt_agent` performs the authoritative live-lineage check itself, so discovery staleness cannot grant authority.
+- **Listing is a snapshot, not a delivery promise** — it may race publication, disposal, or a later message, and another process may activate a child this process reports as `ready`; cross-process accuracy requires a shared lease. `interrupt_agent` performs the authoritative live-lineage check itself, so discovery staleness cannot grant authority.
 - **No pagination or deletion** — the complete stably ordered set is returned, and persisted children remain listed for as long as their sessions remain in persistence; a service-level bound or delete operation is a later product decision.