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

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

packages/app/src/screens/workspace/workspace-screen.tsx

@@ -377,6 +377,9 @@ function getFallbackTabOptionDescription(
   if (tab.target.kind === "browser") {
     return labels.browser;
   }
+  if (tab.target.kind === "provider_subagent") {
+    return labels.agent;
+  }
   return tab.target.path;
 }
 

packages/app/src/screens/workspace/workspace-tab-menu.ts

@@ -138,6 +138,9 @@ function getCloseButtonTestId(tab: WorkspaceTabDescriptor): string {
   if (tab.target.kind === "setup") {
     return `workspace-setup-close-${encodeWorkspaceIdForPathSegment(tab.target.workspaceId)}`;
   }
+  if (tab.target.kind === "provider_subagent") {
+    return `workspace-provider-subagent-close-${tab.target.subagentId}`;
+  }
   return `workspace-file-close-${encodeFilePathForPathSegment(tab.target.path)}`;
 }