fix(ui): preserve draft across prompt history

Stop resetting history navigation on input so editing recalled entries doesn't wipe the bottom draft. Allow ArrowDown navigation while in history and persist the session draft only for fresh prompts.

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

@@ -135,7 +135,6 @@ export default function PromptInput(props: PromptInputProps) {
     instanceFolder: () => props.instanceFolder,
     prompt,
     setPrompt,
-    resetHistoryNavigation,
     getTextarea: () => textareaRef ?? null,
     instanceAgents,
     commands: () => getCommands(props.instanceId),
@@ -303,7 +302,6 @@ export default function PromptInput(props: PromptInputProps) {
     const nextValue = before + insertion + after
 
     setPrompt(nextValue)
-    resetHistoryNavigation()
     setShowPicker(false)
     setAtPosition(null)
 

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

@@ -17,7 +17,6 @@ type PromptPickerOptions = {
 
   prompt: Accessor<string>
   setPrompt: (value: string) => void
-  resetHistoryNavigation?: () => void
   getTextarea: () => HTMLTextAreaElement | null
 
   instanceAgents: Accessor<Agent[]>
@@ -53,7 +52,6 @@ export function usePromptPicker(options: PromptPickerOptions): PromptPickerContr
     const target = e.target as HTMLTextAreaElement
     const value = target.value
     options.setPrompt(value)
-    options.resetHistoryNavigation?.()
 
     const cursorPos = target.selectionStart
 

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

@@ -50,7 +50,11 @@ export function usePromptState(options: PromptStateOptions): PromptState {
 
   const setPrompt = (value: string) => {
     setPromptInternal(value)
-    setSessionDraftPrompt(options.instanceId(), options.sessionId(), value)
+    // Persist drafts only when the user is at the "fresh" position (not browsing history).
+    // This keeps the bottom-of-history draft stable even if the user edits recalled history entries.
+    if (historyIndex() === -1) {
+      setSessionDraftPrompt(options.instanceId(), options.sessionId(), value)
+    }
   }
 
   const clearPrompt = () => {
@@ -121,6 +125,12 @@ export function usePromptState(options: PromptStateOptions): PromptState {
 
     const textarea = selectOptions.getTextarea()
     if (!textarea) return false
+
+    // Only require the cursor to be at the buffer start when *entering* history navigation.
+    // Once we're already navigating history (historyIndex >= 0), allow ArrowUp/ArrowDown
+    // regardless of cursor position (we focus the end of the entry).
+    if (historyIndex() !== -1) return true
+
     return textarea.selectionStart === 0 && textarea.selectionEnd === 0
   }
 
@@ -164,7 +174,7 @@ export function usePromptState(options: PromptStateOptions): PromptState {
       setPrompt(entries[newIndex])
     } else {
       setHistoryIndex(-1)
-      const draft = historyDraft()
+      const draft = historyDraft() ?? getSessionDraftPrompt(options.instanceId(), options.sessionId())
       setPrompt(draft ?? "")
       setHistoryDraft(null)
     }