Agentic UI: open slash-command dropdown when typing / in chat

[sejas]

Related issues

• Fixes STU-2244

How AI was used in this PR

• AI helped writing the code and tests

Proposed Changes

• Typing / in the Agentic UI chat composer now opens the same inline skill-command dropdown that the Classic UI already has: it filters as you type (matching names and descriptions), supports full keyboard navigation (ArrowUp/Down, Enter/Tab to insert, Escape to dismiss), and inserts the chosen command into the draft without stealing focus from the textarea.
• Bare skill prompts (e.g. /rank-me-up) sent from the browser UI are now expanded into the actual skill invocation instruction before reaching the agent. Previously the local web backend passed the literal slash string through, so skills triggered from the browser UI (including the existing “+ → Skills” menu) did not actually run the skill.
• The chat transcript still shows the short /command form the user typed; only the prompt the agent receives is expanded — matching the desktop app behavior.

Testing Instructions

1. Run npm start and start the agentic UI
2. Type / in the composer — the dropdown opens listing the five skills. Keep typing (e.g. /sp) to filter; ArrowUp/Down moves the highlight; Enter or Tab inserts (e.g. /need-for-speed ); Escape closes and removes the unfinished token; clicking an item inserts it while the textarea keeps focus.
3. Verify path/to (slash glued to a word) does not open the dropdown.
4. Send /rank-me-up and confirm the agent actually runs the skill (previously it received the literal string).
5. Test classic UI to check any regressions

slash-command.mp4

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors?

[wpmobilebot]

📊 Performance Test Results

Comparing 92473d4 vs trunk

app-size

Metric	trunk	92473d4	Diff	Change
App Size (Mac)	1406.69 MB	1406.70 MB	+0.01 MB	⚪ 0.0%

site-editor

Metric	trunk	92473d4	Diff	Change
load	1063 ms	1068 ms	+5 ms	⚪ 0.0%

site-startup

Metric	trunk	92473d4	Diff	Change
siteCreation	7542 ms	7529 ms	13 ms	⚪ 0.0%
siteStartup	2882 ms	2869 ms	13 ms	⚪ 0.0%

---

Results are median values from multiple test runs.

Legend: 🟢 Improvement (faster) | 🔴 Regression (slower) | ⚪ No change (<50ms diff)

[bcotrim]

Nice change, thanks!

One issue I ran into: the command picker still work in mid sentences but the command won't actually trigger. Should we display it only at the start of the prompt?

In classic UI we have the "/" button, I wonder if we should keep it, I think it's nice for discoverability. What do you think?

[sejas]

I think that's expected. In claude code you can trigger multiple skills at once if you want. The skill is loaded correctly even if you trigger it in the mid sentence.

[bcotrim]

I think that's expected. In claude code you can trigger multiple skills at once if you want. The skill is loaded correctly even if you trigger it in the mid sentence.

Yes it makes sense in that case, disregard! 🙇

[bcotrim]

Approving after the clarification on the mid sentence commands.
The "/" button is a suggestion we can revisit later