fix(timeline): retain child state and recover rewinds on resume

Provider children now live in the parent's timeline next to its history,
so their descriptors, rows and retirements survive close, archive and a
manager rebuilt over the same backend, and deleting the agent removes
them all. Resuming settles a rewind that was still open when the runtime
stopped instead of leaving its rows half-retired.

A stored child's status is only the last report, possibly from provider
history or an earlier runtime. Workspace activity and idle cleanup now
read the children the current runtime reported running, and closing a
runtime cancels only those, so a child stored as running from an earlier
runtime no longer keeps the agent busy or blocks cleanup.

docs/agent-lifecycle.md

@@ -38,8 +38,8 @@ An unarchived agent may be `closed` without being deleted or archived. Closing r
 processes and subscriptions while retaining its Paseo identity, persistence handle, timeline,
 workspace, labels, title, usage, attention, timestamps, and parent relationship. Opening or prompting
 the agent runs through `ensureAgentLoaded()`, which resumes the durable provider session under the
-same Paseo agent ID. Provider history is not appended again when the canonical timeline is already
-primed.
+same Paseo agent ID. Resume does not read provider history when the agent already has a timeline;
+see [owned history](timeline-sync.md#owned-history).
 
 Reload releases the old runtime before resuming its durable session: an idle provider process can
 still own an exclusive writer. A close failure retains that runtime for cleanup and blocks the
@@ -213,7 +213,8 @@ lifecycle is separate from public workspace visibility and is not a public creat
 Archive is a **soft delete**: the agent record stays on disk with `archivedAt` set, the runtime is closed, and the agent disappears from active lists. Archive is **global** — it lives on the server and propagates to every connected client.
 
 Archive sets `archivedAt`, invokes the provider's native archive hook, and cascades to managed
-children.
+children. The timeline and the provider children stay, so an archived chat reads them without its
+provider; deleting the agent removes them.
 
 `create_agent_request` can opt an agent into `autoArchive`. In that mode the daemon archives the agent after the first terminal turn event (`turn_completed`, `turn_failed`, or `turn_canceled`). When the agent owns an isolated workspace, auto-archive archives that workspace too; the managed worktree is removed when its final workspace reference is gone.
 
@@ -285,6 +286,8 @@ Workspace status is an aggregate activity signal computed **per `workspaceId`**.
 
 Running provider-native subagents contribute `running` to the workspace owned by their parent agent. Their completed, failed, and canceled states stay in the parent's subagents track.
 
+Only the parent's current runtime makes a provider child running. A child's stored status is the last report about it, and that report can come from provider history or from a runtime an earlier daemon ran, so a stored `running` child does not make the workspace running or keep the parent's runtime alive. It counts again once the live session reports it running. Closing a runtime cancels the children that runtime reported running; children it never reported keep their stored status.
+
 A finished workspace can be marked unread after it has been reviewed. The daemon restores
 `finished` attention on its newest eligible workspace-root agent without sending a new completion
 notification. Opening the workspace clears that attention through the normal focus flow.