fix: keep textarea editable during half-question API call

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

.plans/debug_2026-05-18_half_question_textarea_lock.md

@@ -0,0 +1,133 @@
+# Debug Plan: Half Question Button Locks QueryBox
+
+**Date:** 2026-05-18
+**Symptom:** After clicking "Half Question", the textarea appears locked (grayed out, cursor-not-allowed), raising concern that incoming ASR text chunks won't accumulate.
+
+---
+
+## Root Cause Analysis
+
+### The Disable Chain
+
+```
+User clicks "Half Question"
+  → QueryInput.onClick: onHalfQuestion(trimmed)
+  → LTTPage.handleHalfQuestion: queryStream.decomposeOnly({ question })
+  → queries.tsx decomposeOnly: setState({ phase: 'decomposing' })  [IMMEDIATE]
+  → LTTPage: isLoading = true (phase !== 'idle' && !== 'completed' && !== 'error')
+  → QueryInput.textarea: disabled={isLoading} = true            ← TEXTAREA LOCKS
+  → QueryInput.buttons: disabled={isDisabled} = true             ← BUTTONS LOCK
+```
+
+### What ACTUALLY Happens vs What User Perceives
+
+| Concern | Reality |
+|---------|---------|
+| Text accumulation stops? | **No.** React controlled `value={displayValue}` updates even when `disabled`. ASR text continues to display. Playwright confirmed: 250→421 chars during Half Question processing. |
+| Buttons permanently locked? | **No.** When SSE `completed` event arrives, phase→`completed`, `isLoading`→`false`, all re-enabled. |
+| Textarea editable during wait? | **No.** This IS the issue. Textarea is `disabled={isLoading}`, so user cannot edit/select text during the 5-30s LLM decomposition call. |
+
+### The Real Bug
+
+The textarea should NOT be disabled during half-question processing. The half-question feature is meant to be non-blocking — users should be able to:
+
+1. **Continue seeing ASR text accumulate** ✅ (works via controlled component)
+2. **Edit the accumulating text** ❌ (textarea disabled prevents typing/selection)
+3. **Click "Final Submit" later** ❌ (button disabled during API call)
+4. **Click "Half Question" again** ❌ (button disabled during API call)
+
+**But** #2 is the primary concern. Users physically cannot interact with the textarea while the LLM decomposes the question — and they can't even see that text IS still accumulating because the grayed-out disabled style makes it look frozen.
+
+---
+
+## Where Every Prop Wires
+
+```
+frontend/src/pages/LTTPage.tsx
+  line 73:  handleHalfQuestion → queryStream.decomposeOnly({ question })
+  line 81:  isLoading = phase !== 'idle' && !== 'completed' && !== 'error'
+  line 166: <QueryInput isLoading={isLoading} ... />  ← shared isLoading
+
+frontend/src/components/QueryInput.tsx
+  line 52:  isDisabled = isLoading || displayValue.trim() === ''
+  line 66:  <textarea disabled={isLoading} ... />          ← THIS locks the textarea
+  line 81:  <button "Half Question" disabled={isDisabled} />
+  line 89:  <button "Final Submit"  disabled={isDisabled} />
+```
+
+---
+
+## Root Cause Summary
+
+**Line 66 of QueryInput.tsx**: `disabled={isLoading}`
+
+The textarea shares `isLoading` with the buttons. During the API call, `isLoading=true`, which:
+- `disabled` attribute on textarea → gray background, no cursor, no user input
+- Buttons become disabled via `isDisabled` (line 52)
+
+The textarea **does not need to be disabled** during an API call — the buttons are sufficient to prevent duplicate submissions. The textarea should remain interactive so users can continue seeing and editing the accumulating ASR text.
+
+---
+
+## Fix Plan
+
+### Step 1: Remove `disabled={isLoading}` from textarea (line 66)
+
+Change:
+```tsx
+disabled={isLoading}
+```
+To:
+```tsx
+disabled={false}  // or remove the disabled prop entirely
+```
+
+The textarea should never be disabled — `isDisabled` on the buttons already prevents submissions when text is empty.
+
+### Step 2: Keep buttons on `isDisabled` (lines 81, 89)
+
+Buttons continue to use `isDisabled = isLoading || displayValue.trim() === ''` — they remain disabled during API calls AND when text is empty.
+
+### Step 3: (Optional) Remove `disabled:bg-gray-100 disabled:cursor-not-allowed` from textarea CSS
+
+Line 55-57 of the `textareaClassName` includes `disabled:bg-gray-100 disabled:cursor-not-allowed` — if the textarea is no longer disabled, these are inert. Can be removed for cleanliness but not required.
+
+### Risk Assessment
+
+| Risk | Severity | Mitigation |
+|------|----------|------------|
+| User types while LLM uses old text | Low | Half Question already sent with the text at click time. ASR accumulation doesn't invalidate previous half-question results. |
+| Double-click Half Question | Low | `isDisabled` on the button prevents this (isLoading=true during call). |
+| User edits text then clicks Final Submit | None | This is desired behavior. |
+
+### Test Update
+
+File: `frontend/src/test/test_phase2_QueryInput_integration.test.tsx`
+
+No test currently asserts that the textarea is disabled during `isLoading`. Only tests check button disabled state. If any test relies on textarea being disabled, update it to expect `toBeEnabled()`.
+
+---
+
+## Phase Sequence Timeline (decomposeOnly)
+
+```
+t=0ms    setState({ phase: 'decomposing' })    → isLoading=true  (textarea locked, buttons locked)
+t=2s     SSE event 'decomposed' → phase='retrieving'             (still locked)
+t=3s     SSE event 'completed'  → phase='completed'              → isLoading=false (UNLOCKED)
+```
+
+The textarea is locked for ~3 seconds (LLM network round trip + decomposition time). This is the window where users see the grayed-out textarea and think text has stopped accumulating.
+
+---
+
+## Verification Checklist
+
+- [ ] Textarea never gets `disabled` attribute, regardless of `isLoading`
+- [ ] Textarea remains editable/selectable during API calls
+- [ ] ASR partial text continues to display in textarea during API calls
+- [ ] Half Question button disabled during API call (prevents double-click)
+- [ ] Final Submit button disabled during API call
+- [ ] Both buttons re-enable after API call completes
+- [ ] Both buttons disabled when textarea is empty
+- [ ] `pnpm test` passes
+- [ ] Playwright confirms: textarea interactive during ASR streaming + half-question processing

frontend/src/components/QueryInput.tsx

@@ -52,7 +52,7 @@ export const QueryInput: React.FC<QueryInputProps> = ({ onSubmit, onHalfQuestion
   const isDisabled = isLoading || displayValue.trim() === ''
 
   const textareaClassName = [
-    'w-full rounded border border-gray-300 px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500 focus:border-transparent disabled:bg-gray-100 disabled:cursor-not-allowed',
+    'w-full rounded border border-gray-300 px-3 py-2 focus:outline-none focus:ring-2 focus:ring-blue-500 focus:border-transparent',
     showPartialStyle ? 'text-gray-400 italic' : '',
   ].filter(Boolean).join(' ')
 
@@ -63,7 +63,6 @@ export const QueryInput: React.FC<QueryInputProps> = ({ onSubmit, onHalfQuestion
         onChange={handleChange}
         onKeyDown={handleKeyDown}
         placeholder="Ask a question about your documents..."
-        disabled={isLoading}
         rows={3}
         className={textareaClassName}
       />

frontend/src/test/components/QueryInput.test.tsx

@@ -43,10 +43,10 @@ describe('QueryInput', () => {
     expect(button).toBeDisabled()
   })
 
-  it('textarea is disabled when isLoading is true', () => {
+  it('textarea is NOT disabled when isLoading is true (remains editable)', () => {
     render(<QueryInput onSubmit={mockOnSubmit} isLoading={true} />)
     const textarea = screen.getByPlaceholderText('Ask a question about your documents...')
-    expect(textarea).toBeDisabled()
+    expect(textarea).toBeEnabled()
   })
 
   it('button is disabled when isLoading is true even with text', () => {