fix(tui): keep long sessions responsive and bound resumed history

.changeset/long-session-tui-performance.md

@@ -0,0 +1,7 @@
+---
+"@moonshot-ai/kimi-code": patch
+"@moonshot-ai/kimi-code-sdk": patch
+"@moonshot-ai/agent-core": patch
+---
+
+Improve TUI performance and resume speed for long-running sessions.

.changeset/pi-tui-frame-line-reuse.md

@@ -0,0 +1,5 @@
+---
+"@moonshot-ai/pi-tui": patch
+---
+
+Speed up the terminal renderer in long sessions by reusing processed lines across frames.

apps/kimi-code/src/tui/commands/undo.ts

@@ -107,8 +107,9 @@ async function undoByCount(host: SlashCommandHost, count: number): Promise<boole
   const children = host.state.transcriptContainer.children;
   const lastUserComponentIndex = findUndoAnchorComponentIndex(children, count);
   if (lastUserComponentIndex !== undefined) {
+    // Structural removal only: the container's ref-checked render cache
+    // detects the child-list change; no tree-wide invalidate needed.
     removeUndoContextComponents(children, lastUserComponentIndex);
-    host.state.transcriptContainer.invalidate();
   }
 
   const preservedEntries = entries.slice(lastUserIndex).filter(

apps/kimi-code/src/tui/components/chrome/gutter-container.ts

@@ -7,6 +7,12 @@
  * prefixed with `left` plain spaces. Right padding is logical only — we
  * never emit trailing spaces, since terminals already paint background to
  * the edge and adding them would just churn the diff renderer.
+ *
+ * The render cache below validates per child (component identity + the
+ * identity of its rendered line array), so structural child-list changes —
+ * append, splice-removal, in-place replacement — are picked up correctly
+ * without a tree-wide `invalidate()`. Reserve `invalidate()` for global
+ * style changes that genuinely dirty every child (e.g. theme switches).
  */
 
 import { Container } from '@moonshot-ai/pi-tui';

apps/kimi-code/src/tui/components/messages/step-summary.ts

@@ -3,21 +3,24 @@ import type { Component } from '@moonshot-ai/pi-tui';
 import { currentTheme } from '#/tui/theme';
 
 /**
- * A collapsed summary of older steps within a turn. Accumulates counts of
- * merged steps (thinking blocks and tool calls) and renders them as a single
- * muted line, e.g. `… thinking 5 times, call 50 tools`.
+ * A collapsed summary of older content within a turn. Accumulates counts of
+ * merged steps (thinking blocks and tool calls) and folded assistant messages,
+ * rendering them as a single muted line, e.g.
+ * `… thinking 5 times, call 50 tools, 12 messages`.
  */
 export class StepSummaryComponent implements Component {
   private thinking = 0;
   private tool = 0;
+  private message = 0;
 
   get isEmpty(): boolean {
-    return this.thinking === 0 && this.tool === 0;
+    return this.thinking === 0 && this.tool === 0 && this.message === 0;
   }
 
-  addCounts(thinking: number, tool: number): void {
+  addCounts(thinking: number, tool: number, message = 0): void {
     this.thinking += thinking;
     this.tool += tool;
+    this.message += message;
   }
 
   invalidate(): void {}
@@ -26,6 +29,7 @@ export class StepSummaryComponent implements Component {
     const parts: string[] = [];
     if (this.thinking > 0) parts.push(`thinking ${this.thinking} times`);
     if (this.tool > 0) parts.push(`call ${this.tool} tools`);
+    if (this.message > 0) parts.push(`${this.message} messages`);
     if (parts.length === 0) return [];
     return [currentTheme.dim(`\u2026 ${parts.join(', ')}`)];
   }

apps/kimi-code/src/tui/components/messages/user-message.ts

@@ -96,3 +96,17 @@ export class UserMessageComponent implements Component {
 function isImageLine(line: string): boolean {
   return line.includes('\u001B_G') || line.includes('\u001B]1337;File=');
 }
+
+/**
+ * Invisible turn-boundary marker for replay. Some replayed records start a
+ * new turn without anything to show — the goal driver's synthetic
+ * continuation prompt is model-facing and never rendered live — but the
+ * transcript still needs a mounted boundary component so step/assistant
+ * folding (and window trimming) can find the turn edges. Renders zero lines.
+ */
+export class ReplayTurnBoundaryComponent implements Component {
+  invalidate(): void {}
+  render(_width: number): string[] {
+    return [];
+  }
+}

apps/kimi-code/src/tui/controllers/session-event-handler.ts

@@ -936,8 +936,9 @@ export class SessionEventHandler {
     const children = state.transcriptContainer.children;
     const idx = children.indexOf(spinner);
     if (idx >= 0) {
+      // In-place replacement is picked up by the container's ref-checked
+      // render cache; a tree-wide invalidate is unnecessary (and costly).
       children[idx] = status;
-      state.transcriptContainer.invalidate();
     } else {
       state.transcriptContainer.addChild(status);
     }

apps/kimi-code/src/tui/controllers/session-replay.ts

@@ -10,6 +10,7 @@ import type {
 } from '@moonshot-ai/kimi-code-sdk';
 
 import { ToolCallComponent } from '../components/messages/tool-call';
+import { ReplayTurnBoundaryComponent } from '../components/messages/user-message';
 import { currentTheme } from '../theme';
 import type { TodoItem } from '../components/chrome/todo-panel';
 import type {
@@ -23,6 +24,7 @@ import { formatBackgroundAgentTranscript } from '../utils/background-agent-statu
 import { formatBackgroundTaskTranscript } from '../utils/background-task-status';
 import { buildGoalCompletionMessage } from '../utils/goal-completion';
 import { formatBashOutputForDisplay } from '../utils/shell-output';
+import { markTranscriptComponent } from '../utils/transcript-component-metadata';
 import {
   appStateFromResumeAgent,
   backgroundOrigin,
@@ -305,6 +307,16 @@ export class SessionReplayRenderer {
     // reminders, stop-hook reasons, …) are model-facing only: the live event
     // stream never renders them, so replay must not leak them either.
     if (message.origin?.kind === 'system_trigger') {
+      if (message.origin.name === 'goal_continuation') {
+        // The goal driver's synthetic "continue" prompt starts a new replay
+        // turn even though nothing visible is mounted: advance the turn and
+        // mark an invisible boundary so each goal round groups under its own
+        // turn and step/assistant folding can find the turn edges.
+        this.advanceTurn(context);
+        const boundary = new ReplayTurnBoundaryComponent();
+        markTranscriptComponent(boundary, replayEntry(context, 'user', '', 'plain'));
+        this.host.state.transcriptContainer.addChild(boundary);
+      }
       return;
     }
 
@@ -647,8 +659,9 @@ export class SessionReplayRenderer {
       (child) => child instanceof ToolCallComponent && child.toolCallView.id === toolCallId,
     );
     if (childIndex >= 0) {
+      // Structural removal only: the container's ref-checked render cache
+      // detects the child-list change; no tree-wide invalidate needed.
       children.splice(childIndex, 1);
-      state.transcriptContainer.invalidate();
     }
   }
 

apps/kimi-code/src/tui/controllers/streaming-ui.ts

@@ -36,6 +36,7 @@ export interface StreamingUIHost {
   shiftQueuedMessage(): QueuedMessage | undefined;
   pushTranscriptEntry(entry: TranscriptEntry): void;
   mergeCurrentTurnSteps(): void;
+  mergeCompletedTurnAssistants(): void;
 }
 
 export class StreamingUIController {
@@ -555,6 +556,9 @@ export class StreamingUIController {
     const completedTurnKey =
       this._currentTurnId ?? `local:${String(state.appState.streamingStartTime)}`;
     this.finalizeLiveTextBuffers('idle');
+    // The finished turn keeps only its conclusion-bearing tail; intermediate
+    // chatter folds into the step summary.
+    this.host.mergeCompletedTurnAssistants();
     this.resetToolCallState();
     this._currentTurnId = undefined;
 
@@ -835,8 +839,9 @@ export class StreamingUIController {
     const children = state.transcriptContainer.children;
     const idx = children.indexOf(solo);
     if (idx >= 0) {
+      // In-place replacement is picked up by the container's ref-checked
+      // render cache; a tree-wide invalidate is unnecessary (and costly).
       children[idx] = group;
-      state.transcriptContainer.invalidate();
     } else {
       state.transcriptContainer.addChild(group);
     }
@@ -892,8 +897,9 @@ export class StreamingUIController {
     const children = state.transcriptContainer.children;
     const idx = children.indexOf(solo);
     if (idx >= 0) {
+      // In-place replacement is picked up by the container's ref-checked
+      // render cache; a tree-wide invalidate is unnecessary (and costly).
       children[idx] = group;
-      state.transcriptContainer.invalidate();
     } else {
       state.transcriptContainer.addChild(group);
     }

apps/kimi-code/src/tui/controllers/subagent-event-handler.ts

@@ -552,8 +552,9 @@ export class SubAgentEventHandler {
     const children = this.host.state.transcriptContainer.children;
     const index = children.indexOf(progress);
     if (index >= 0) {
+      // Structural removal only: GutterContainer's ref-checked render cache
+      // detects the child-list change; no tree-wide invalidate needed.
       children.splice(index, 1);
-      this.host.state.transcriptContainer.invalidate();
     }
     this.host.updateActivityPane();
   }