fix(ui): preserve prompt text when dismissing mention picker (#285)

## Summary
- preserve the current prompt text when dismissing the `@` mention/file
picker with `Esc`
- let `Enter` fall back to normal prompt submission when the mention
picker is open but there is no selectable result

## Verification
- source inspection of the prompt input and picker flow
- local `npm run typecheck --workspace @codenomad/ui` is blocked in this
environment because workspace dependencies are not installed

--
Yours,
[CodeNomadBot](https://github.com/NeuralNomadsAI/CodeNomad)

Co-authored-by: Shantur Rathore <i@shantur.com>

packages/ui/src/components/prompt-input.tsx

@@ -540,6 +540,10 @@ export default function PromptInput(props: PromptInputProps) {
               mode={pickerMode()}
               onClose={handlePickerClose}
               onSelect={handlePickerSelect}
+              onSubmitWithoutSelection={() => {
+                handlePickerClose()
+                void handleSend()
+              }}
               agents={instanceAgents()}
               commands={getCommands(props.instanceId)}
               instanceClient={instance()!.client}

packages/ui/src/components/prompt-input/usePromptPicker.ts

@@ -324,28 +324,6 @@ export function usePromptPicker(options: PromptPickerOptions): PromptPickerContr
     const pos = atPosition()
     if (pickerMode() === "mention" && pos !== null) {
       setIgnoredAtPositions((prev) => new Set(prev).add(pos))
-
-      // Remove the partial @mention text from the textarea when ESC is pressed
-      const textarea = options.getTextarea()
-      if (textarea) {
-        const currentPrompt = options.prompt()
-        const cursorPos = textarea.selectionStart
-        // Remove text from @ position to cursor position
-        const before = currentPrompt.substring(0, pos)
-        const after = currentPrompt.substring(cursorPos)
-        options.setPrompt(before + after)
-
-        // Restore cursor position to where @ was
-        setTimeout(() => {
-          const nextTextarea = options.getTextarea()
-          if (nextTextarea) {
-            nextTextarea.setSelectionRange(pos, pos)
-          }
-        }, 0)
-
-        // Clear ignoredAtPositions so typing @ again will work
-        setIgnoredAtPositions(new Set<number>())
-      }
     }
     setShowPicker(false)
     setAtPosition(null)

packages/ui/src/components/unified-picker.tsx

@@ -79,6 +79,7 @@ interface UnifiedPickerProps {
   mode?: "mention" | "command"
   onSelect: (item: PickerItem, action: PickerSelectAction) => void
   onClose: () => void
+  onSubmitWithoutSelection?: () => void
   agents: Agent[]
   commands?: SDKCommand[]
   instanceClient: OpencodeClient | null
@@ -404,6 +405,8 @@ const UnifiedPicker: Component<UnifiedPickerProps> = (props) => {
       if (selected) {
         const action: PickerSelectAction = e.key === "Tab" ? "tab" : e.shiftKey ? "shiftEnter" : "enter"
         props.onSelect(selected, action)
+      } else if (e.key === "Enter" && mode() === "mention") {
+        props.onSubmitWithoutSelection?.()
       }
     } else if (e.key === "Escape") {
       e.preventDefault()