feat(composer): recall sent messages with the arrow keys

CHANGELOG.md

@@ -19,6 +19,9 @@ version with its date and start a fresh empty `[Unreleased]` above it.
 - An update icon appears in the view header when GitHub has a newer stable
   release; click it to open Qoderian's plugin page, where Obsidian's update
   button lives.
+- With the message input empty, ArrowUp walks back through the messages you
+  sent in this conversation and ArrowDown walks forward again, so you can
+  recall, edit, or resend an earlier prompt without scrolling the transcript.
 
 ### Changed
 

src/features/chat/controllers/input-controller.ts

@@ -31,6 +31,7 @@ import type { BrowserSelectionController } from './browser-selection-controller'
 import type { CanvasSelectionController } from './canvas-selection-controller';
 import type { ConversationController } from './conversation-controller';
 import { InputCommandController } from './input-command-controller';
+import { PromptHistoryController } from './prompt-history-controller';
 import { QueuedMessageController } from './queued-message-controller';
 import { cloneChatTurnRequest, type QueuedChatTurn } from './queued-turn';
 import type { SelectionController } from './selection-controller';
@@ -76,6 +77,7 @@ export class InputController {
   private deps: InputControllerDeps;
   private readonly approvalFlow: ApprovalFlowController;
   private readonly inputCommands: InputCommandController;
+  private readonly promptHistory: PromptHistoryController;
   private readonly queuedMessages: QueuedMessageController;
   private activeStreamingAssistantMessage: ChatMessage | null = null;
   // While a steer splice is swapping the render target (finalizing the old
@@ -134,6 +136,11 @@ export class InputController {
         });
       },
     });
+    this.promptHistory = new PromptHistoryController({
+      getInputEl: deps.getInputEl,
+      getMessages: () => deps.state.messages,
+      getConversationId: () => deps.state.currentConversationId,
+    });
   }
 
   private getAgentService(): ChatRuntime | null {
@@ -1106,6 +1113,12 @@ export class InputController {
     return this.inputCommands.handleResumeKeydown(e);
   }
 
+  handlePromptHistoryKeydown(e: KeyboardEvent): boolean {
+    // An armed instruction mode (#) owns the empty composer; leave the arrows alone.
+    if (this.deps.getInstructionModeManager()?.isActive()) return false;
+    return this.promptHistory.handleKeydown(e);
+  }
+
   isResumeDropdownVisible(): boolean {
     return this.inputCommands.isResumeDropdownVisible();
   }

src/features/chat/controllers/prompt-history-controller.ts

@@ -0,0 +1,107 @@
+import type { ChatMessage } from '../../../core/types';
+import { extractUserDisplayContent } from '../../../qoder/prompt/context/prompt-context';
+import { autoResizeTextarea } from '../ui/textarea-resize';
+
+export interface PromptHistoryControllerDeps {
+  getInputEl: () => HTMLTextAreaElement;
+  getMessages: () => ChatMessage[];
+  getConversationId: () => string | null;
+}
+
+/**
+ * ArrowUp in an empty composer walks back through the messages sent in the
+ * current session; ArrowDown walks forward again and finally back to the empty
+ * draft. Browsing is considered intact only while the composer still shows the
+ * entry that was last recalled, so typing, sending, or switching conversations
+ * drops out of history mode.
+ */
+export class PromptHistoryController {
+  private entries: string[] = [];
+  private position = 0;
+  private sourceConversationId: string | null = null;
+
+  constructor(private readonly deps: PromptHistoryControllerDeps) {}
+
+  /** Returns true when the key was consumed as history navigation. */
+  handleKeydown(event: KeyboardEvent): boolean {
+    if (event.isComposing) return false;
+    if (event.shiftKey || event.ctrlKey || event.metaKey || event.altKey) return false;
+    if (event.key === 'ArrowUp') return this.showPreviousEntry(event);
+    if (event.key === 'ArrowDown') return this.showNextEntry(event);
+    return false;
+  }
+
+  private showPreviousEntry(event: KeyboardEvent): boolean {
+    if (!this.isBrowsingIntact()) {
+      if (this.deps.getInputEl().value.length > 0) return false;
+      this.entries = this.collectSentMessages();
+      if (this.entries.length === 0) return false;
+      this.position = this.entries.length;
+      this.sourceConversationId = this.deps.getConversationId();
+    }
+
+    if (this.position === 0) return false;
+
+    this.position -= 1;
+    this.restoreEntry(this.entries[this.position]);
+    event.preventDefault();
+    return true;
+  }
+
+  private showNextEntry(event: KeyboardEvent): boolean {
+    if (!this.isBrowsingIntact()) return false;
+    if (this.position >= this.entries.length) return false;
+
+    this.position += 1;
+    event.preventDefault();
+
+    if (this.position === this.entries.length) {
+      this.clearInput();
+      return true;
+    }
+
+    this.restoreEntry(this.entries[this.position]);
+    return true;
+  }
+
+  private isBrowsingIntact(): boolean {
+    if (this.entries.length === 0) return false;
+    if (this.sourceConversationId !== this.deps.getConversationId()) return false;
+
+    const shown = this.position < this.entries.length ? this.entries[this.position] : '';
+    return this.deps.getInputEl().value === shown;
+  }
+
+  private collectSentMessages(): string[] {
+    const entries: string[] = [];
+
+    for (const message of this.deps.getMessages()) {
+      if (message.role !== 'user') continue;
+      if (message.isInterrupt || message.isRebuiltContext) continue;
+
+      const text = this.getDisplayText(message).trim();
+      if (text.length > 0) entries.push(text);
+    }
+
+    return entries;
+  }
+
+  private getDisplayText(message: ChatMessage): string {
+    return message.displayContent
+      ?? extractUserDisplayContent(message.content)
+      ?? message.content;
+  }
+
+  private restoreEntry(text: string): void {
+    const inputEl = this.deps.getInputEl();
+    inputEl.value = text;
+    autoResizeTextarea(inputEl);
+    inputEl.setSelectionRange(text.length, text.length);
+  }
+
+  private clearInput(): void {
+    const inputEl = this.deps.getInputEl();
+    inputEl.value = '';
+    autoResizeTextarea(inputEl);
+  }
+}

src/features/chat/tabs/tab-input-events.ts

@@ -49,6 +49,7 @@ export function wireTabInputEvents(tab: TabData, plugin: QoderianPlugin): void {
     if (ui.instructionModeManager?.handleKeydown(event)) return;
     if (sendTabInputMessageFromExplicitEnterShortcut(tab, event)) return;
     if (handleDropdownKeydown(event)) return;
+    if (controllers.inputController?.handlePromptHistoryKeydown(event)) return;
 
     if (event.key === 'Escape' && !event.isComposing && state.isStreaming) {
       event.preventDefault();