bug(tui): subagent navigation broken for nested sessions and imprecise for multiple concurrent tasks

[guazi04]

Summary

After #15607 replaced BlockTool (with onClick) with InlineTool (keybind-only) for the Task component, subagent session navigation has two issues:

1. session_child_first does not work in nested subagent sessions

Steps to reproduce:

1. Start a session that spawns a subagent (task tool)
2. Press <leader>down (session_child_first) to enter the child session — works fine
3. If that child session also spawns subagents, press <leader>down again — nothing happens

Root cause:

children() in session/index.tsx (line 125-130) computes siblings, not descendants:

const children = createMemo(() => {
  const parentID = session()?.parentID ?? session()?.id
  return sync.data.session
    .filter((x) => x.parentID === parentID || x.id === parentID)
    .toSorted(...)
})

When already inside a child session, session()?.parentID is set, so parentID resolves to the grandparent. children() then returns the current session's siblings, not its children. moveFirstChild() searches these siblings for one with parentID set — which finds a sibling, not a deeper child.

2. No way to navigate to a specific subagent when multiple tasks are concurrent

Previously, each BlockTool Task had an onClick handler that navigated directly to that specific subagent's session. Now the only option is:

1. session_child_first → jumps to the first child
2. left/right → cycle through siblings

When an agent spawns 3+ concurrent subagent tasks, there's no way to directly enter a specific one. You have to cycle blindly, which is significantly worse UX than the previous click-to-enter behavior.

Suggestion

Consider one or more of:

• Restore onClick on Task items (re-add click-to-navigate via BlockTool or add onClick to InlineTool)
• Fix children() / moveFirstChild() to support arbitrary nesting depth
• Add a picker UI (e.g., a dialog listing child sessions) when session_child_first is pressed and multiple children exist

Environment

• Commit: 5dcf330 (dev branch)
• Introduced in: 90270c6 (feat(tui): improve task tool display with subagent keybind hints and spinner animations #15607)
• File: packages/opencode/src/cli/cmd/tui/routes/session/index.tsx

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• Clicking on Task tool no longer navigates to subagent session #15769: Same root cause (commit 90270c615 replacing BlockTool with InlineTool removing onClick navigation) — covers the "no way to navigate to a specific subagent" point directly
• session_child_cycle + session_child_cycle_reverse stopped working #10444: session_child_cycle / session_child_first keybinds not working as expected for subagent navigation

If these don't fully cover your report (particularly the nested subagent children() logic bug), please clarify what's new so maintainers can decide whether to keep this open or consolidate.

[guazi04]

Thanks for flagging the potential duplicates. After reviewing them:

Re #15769 — covers the same click-to-navigate regression (Bug 2 in this issue). Our fix restores BlockTool with onClick directly on the Task component, rather than making the hint text clickable (which is the approach in PR #15770). Both address the same root cause from 90270c615.

Re #10444 — related but distinct. That issue covers session_child_cycle / session_child_cycle_reverse not working at all (terminal key parsing + guard logic). Our Bug 1 is specifically about session_child_first / moveFirstChild() not drilling into nested subagents because children() computes siblings rather than the current session's own children. The fix adds a separate subagents memo scoped to direct children of the viewed session, leaving children() untouched.

So this issue covers ground that partially overlaps with #15769 (Bug 2) but also includes the nested navigation logic bug (Bug 1) which is not reported there. Happy to consolidate if maintainers prefer.

[diegonix]

Confirming this bug — regression from PR #14814 in v1.2.16

I can confirm this issue. I've been using OpenCode daily and this is a clear regression introduced in v1.2.16. Navigation with Ctrl+X + Down Arrow into nested sub-agents (sub-sub-agents / grandchildren) is completely broken — it only traverses one level deep.

What changed

In v1.2.15, the old keybindings (Ctrl+X Left/Right) cycled through all agents flatly — the main agent and every sub-agent regardless of nesting depth. This worked correctly for multi-level sub-agent trees.

In v1.2.16, PR #14814 ("Change keybindings to navigate between child sessions" by @jlongster) introduced a new hierarchical navigation model:

Ctrl+X Down → enter the child session level
Left/Right → cycle between sibling sub-agents
Up → go back to the parent

While the hierarchical approach is a great UX improvement in concept, the implementation only works for the first level of children. When a sub-agent spawns another sub-agent (which is common with tools like Task/background_task), pressing Down again from a child session does nothing — the grandchild sessions are unreachable.

Steps to reproduce

Install OpenCode v1.2.16
Give the agent a task complex enough that it spawns a sub-agent via Task, and that sub-agent also spawns its own sub-agent (2+ levels deep)
Press Ctrl+X Down to navigate into the first-level sub-agent ✅ works
Press Ctrl+X Down again to navigate into the second-level sub-agent ❌ nothing happens

Expected behavior

Ctrl+X Down should recursively navigate deeper into the sub-agent hierarchy, allowing access to any nesting depth. The Up key should then walk back up through each parent level.

Environment

OpenCode version: v1.2.16
OS: Ubuntu 24.04 (Linux x64)
Previous version: v1.2.15 (worked correctly with the old flat navigation)