fix(tui): fix nested subagent navigation and restore click-to-navigate on tasks

[guazi04]

Issue for this PR

Closes#15972

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

After #15607 replaced BlockTool (clickable) with InlineTool (keybind-only) for the Task component, two navigation regressions were introduced:

Bug 1: session_child_first keybind broken for nested subagents

children() computes siblings (sessions sharing the same parent), not the current session's own children. When you're already inside a child session and press the keybind, moveFirstChild() searches siblings instead of deeper children, so it can't drill down further.

Fix: Added a subagents memo that filters for parentID === route.sessionID (direct children of the currently viewed session). moveFirstChild() now uses subagents()[0] instead of searching children(). The original children() memo is untouched — it's still used by permissions() and questions() for sibling-level aggregation.

Bug 2: No way to navigate to a specific subagent when multiple tasks run concurrently

Previously each Task had an onClick handler via BlockTool that navigated directly to that subagent's session. After #15607, the only option is session_child_first → first child → cycle with left/right, which is imprecise.

Fix: Task component now uses BlockTool with onClick when sessionId exists (restoring click-to-navigate), falling back to InlineTool when no sessionId is available. All #15607 improvements (spinner, toolcall count, keybind hints) are preserved.

How did you verify your code works?

• Reviewed the navigation logic: subagents memo correctly scopes to direct children at any depth, children() still serves sibling aggregation for permissions/questions
• Verified moveChild() has proper empty-array guard after the original guard was removed
• Confirmed BlockTool onClick handler matches the pattern used in the codebase before feat(tui): improve task tool display with subagent keybind hints and spinner animations #15607
• LSP diagnostics show no new errors (all existing errors are pre-existing Solid.js JSX children false positives)

Screenshots / recordings

N/A — terminal TUI change, navigation behavior only.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Potential Duplicate PRs Found:

1. PR fix(tui): make "view subagents" hint clickable to restore Task click-to-navigate #15770 - "fix(tui): make "view subagents" hint clickable to restore Task click-to-navigate"

   • fix(tui): make "view subagents" hint clickable to restore Task click-to-navigate #15770
   • Related Issue: This appears to be addressing the same click-to-navigate regression on tasks that PR fix(tui): fix nested subagent navigation and restore click-to-navigate on tasks #15974 is fixing. Both PRs seem to be working on restoring the ability to click on tasks to navigate to subagent sessions.

2. PR fix(opencode): collect nested subagent sessions in TUI sidebar #15820 - "fix(opencode): collect nested subagent sessions in TUI sidebar"

   • fix(opencode): collect nested subagent sessions in TUI sidebar #15820
   • Related Issue: This may address nested subagent collection which could overlap with the nested navigation fix in PR fix(tui): fix nested subagent navigation and restore click-to-navigate on tasks #15974.

Why they're related: PR #15974 fixes both nested subagent navigation (the moveFirstChild() logic) and click-to-navigate on tasks (BlockTool vs InlineTool). PR #15770 specifically targets the click-to-navigate issue, and PR #15820 deals with nested subagent session collection in the sidebar—both are closely related areas of the TUI subagent navigation system.

[github-actions]

Thanks for updating your PR! It now meets our contributing guidelines. 👍

[guazi04]

Regarding the flagged potential duplicates:

vs PR #15770 — Both fix the click-to-navigate regression. #15770 makes the "view subagents" hint text clickable (adds hover/click to a <box> around the hint in AssistantMessage). This PR instead restores BlockTool with onClick on the Task component itself, which is closer to the pre-#15607 behavior — users click the task block directly, not a hint label. Additionally, this PR preserves all the #15607 improvements (spinner, toolcall count, keybind hints) by using a <Switch> between BlockTool (when sessionId exists) and InlineTool (fallback).

vs PR #15820 — Both fix nested subagent navigation. #15820 rewrites children() to BFS-collect all descendants from the root session, which changes the semantics of children() globally — callers like permissions() and questions() that aggregate at the sibling level would now see the entire tree. This PR takes a more conservative approach: adds a new subagents memo (session.filter(x => x.parentID === route.sessionID)) used only by moveFirstChild(), leaving children() untouched so existing sibling-level aggregation is unaffected.

Both bugs are fixed in a single file change with minimal blast radius.

[nexxeln]

Actually there is a problem. Please keep the Task row visually inline. This change swaps Task from InlineTool to BlockTool, which changes intended UI (panel/border/hover block). Can you restore click-to-navigate while preserving the existing inline presentation (e.g. inline click target or InlineTool click support)?

[nexxeln]

I'm gonna be tackling this myself, so closing this. Thank you for your contribution.

[guazi04]

Hey @nexxeln, I went ahead and addressed the feedback before seeing the close — here's the approach in case it's useful as reference:

InlineTool click support (keeps inline visual, no BlockTool swap):

• Added optional onClick prop to InlineTool
• Wired onMouseOver/onMouseOut/onMouseUp on the outer <box> (same selection-check pattern as BlockTool)
• Hover feedback: text fg brightens from contextual color to theme.text — no border, padding, or background change
• Spinner branch also gets hover color for consistent clickability feedback

Task component always renders <InlineTool> with onClick when sessionId exists:

constsid=props.metadata.sessionIdreturn(<InlineToolicon="│"spinner={isRunning()}complete={props.input.description}pending="Delegating..."part={props.part}onClick={sid ? ()=>navigate({type: "session",sessionID: sid}) : undefined}>{content()}</InlineTool>)

Full diff on the branch: 94b7888...4f36ef6

Good luck with the fix! 🙌