Studio Code: don't wipe in-progress typing on turn boundaries

[youknowriad]

Related issues

• Related to: in-session bug report — while Studio Code's agent is running, text the user is typing into the prompt sometimes disappears (most often right when the agent finishes a turn).

How AI was used in this PR

Investigated the AiChatUI lifecycle, identified the two editor.setText('') calls that fire across turn boundaries, and removed them after confirming pi-tui already clears the editor on submit.

Proposed Changes

• Remove this.editor.setText('') from AiChatUI.waitForInput() and AiChatUI.beginAgentTurn() in apps/cli/ai/ui.ts.

The TUI editor stays focused while the agent runs, so users can keep typing during a turn. pi-tui's Editor.submitValue() already clears the editor synchronously when the user presses Enter, so the additional setText('') calls only ever fire on text the user typed during the async gap around turn start/end:

• waitForInput — runs after the agent returns control. If you typed (without pressing Enter) while the turn was finishing, those characters get wiped here. This is the case the bug report described.
• beginAgentTurn — runs after several awaits in runAgentTurn (provider/env setup). Anything typed in that gap also gets wiped.

In both cases the editor is already empty in the normal flow (because submitValue cleared it), so removing these calls is a no-op except in the race window where the user's input was being lost.

Testing Instructions

1. npm run cli:build && node apps/cli/dist/cli/main.mjs — start Studio Code.
2. Send any prompt that triggers a multi-step agent turn.
3. While the agent is running, start typing into the prompt (without pressing Enter).
4. Wait for the turn to complete.
5. Before this PR: the typed text disappears the moment the turn ends. After this PR: the text stays in the editor, ready to submit.
6. Sanity-check that the normal submit-and-clear flow still works (press Enter on a prompt → editor clears as expected).

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors? (Pre-existing typecheck errors on trunk are unrelated.)

🤖 Generated with Claude Code

[wpmobilebot]

📊 Performance Test Results

Comparing f39b1f2 vs trunk

app-size

Metric	trunk	f39b1f2	Diff	Change
App Size (Mac)	1454.06 MB	1454.06 MB	+0.00 MB	⚪ 0.0%

site-editor

Metric	trunk	f39b1f2	Diff	Change
load	1494 ms	1502 ms	+8 ms	⚪ 0.0%

site-startup

Metric	trunk	f39b1f2	Diff	Change
siteCreation	8086 ms	8080 ms	6 ms	⚪ 0.0%
siteStartup	4934 ms	4923 ms	11 ms	⚪ 0.0%

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Results are median values from multiple test runs.

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