Show provider subagents in the subagents track (#2013)

* Add provider-owned subagent stream contract

* OpenCode provider: detect child sessions, attach adopted children to the hosting server, synthesize external turns

- Emit internal provider_child_session_detected / provider_session_deleted stream events from the global event stream (before the no-active-turn gate), including BFS hydration of existing descendants on subscribe
- Track child sessions in a registry mapping child session id -> hosting server url; resumeSession attaches via acquireExisting() so adopted children share the parent's server generation and keep receiving live events
- Synthesize external turns for adopted (externally driven) sessions so timeline, tool calls, and permission requests stream without a Paseo-initiated prompt
- Honor launchContext.env in resumeSession (acquireDedicated parity with createSession)
- Stop folding child tool parts into the parent's sub_agent action log; the parent row stays as a pointer

* Render provider subagents in workspace timelines

* fix provider subagent timeline reliability

* fix provider subagent lifecycle edge cases

* fix provider subagent event fidelity

* Fix provider subagent history fidelity

* Fix restored provider subagent state

* Fix provider subagent visibility edges

* Restore provider subagent timelines

* Page provider subagent history

* Forward subagent questions reliably

* fix(subagents): preserve OpenCode child context

* fix(subagents): harden provider timeline routing

* fix(subagents): preserve provider page continuity

* fix(subagents): retain live child prompts

---------

Co-authored-by: Omer <639682+omercnet@users.noreply.github.com>

packages/app/src/contexts/session-context.tsx

@@ -78,6 +78,7 @@ import {
   applyLegacyDaemonWorkspaceOwnership,
   backfillLegacyDaemonWorkspaceDirectoryIfEmpty,
 } from "@/workspace/legacy-daemon-workspaces";
+import { useProviderSubagentStore } from "@/subagents/provider-store";
 
 // Re-export types from session-store and draft-store for backward compatibility
 export type { DraftInput } from "@/stores/draft-store";
@@ -1349,6 +1350,11 @@ function SessionProviderInternal({ children, serverId, client }: SessionProvider
       applyTimelineResponse(message.payload);
     });
 
+    const unsubProviderSubagentUpdate = client.on("agent.provider_subagents.update", (message) => {
+      if (message.type !== "agent.provider_subagents.update") return;
+      useProviderSubagentStore.getState().applyUpdate(serverId, message.payload);
+    });
+
     const unsubWorkspaceUpdate = client.on("workspace_update", (message) => {
       if (message.type !== "workspace_update") return;
       if (message.payload.kind === "remove") {
@@ -1750,6 +1756,7 @@ function SessionProviderInternal({ children, serverId, client }: SessionProvider
       unsubAgentUpdate();
       unsubAgentStream();
       unsubAgentTimeline();
+      unsubProviderSubagentUpdate();
       unsubWorkspaceUpdate();
       unsubScriptStatusUpdate();
       unsubCheckoutStatusUpdate();