Fix rendering duplication, overlap, and input leaks

.claude/CLAUDE.md

@@ -76,8 +76,8 @@ Only update the `Status` field. Do not modify any other frontmatter or prompt co
 
 <!-- BEGIN:REPO:current-state -->
 ## Current State
-Branch: `feature/version-1.0.0-alpha.72`
-In-progress: PR shellicar/claude-cli#160 open, auto-merge enabled. Awaiting CodeQL and merge. Phase 2 (github-release) to follow after merge.
+Branch: `main`
+In-progress: PR shellicar/claude-cli#162 open, auto-merge enabled. Awaiting CodeQL and merge.
 <!-- END:REPO:current-state -->
 
 <!-- BEGIN:REPO:architecture -->

.claude/sessions/2026-03-30.md

@@ -1,3 +1,31 @@
+### 07:15 - fix/rendering-duplication Phase 2 (#161)
+
+- Did: Pushed `fix/161-rendering-duplication` branch; created PR shellicar/claude-cli#162 with `Closes #161`, milestone `1.0`, label `bug`, reviewer `bananabot9000`, auto-merge enabled. Build and signature checks passed; CodeQL in progress.
+- Files: (no code changes)
+- Decisions: None.
+- Next: Nothing. PR will auto-merge when CodeQL passes.
+
+### 07:01 - fix/rendering-duplication Phase 1 (#161)
+
+- Did: Fixed three rendering bugs: (1) split embedded newlines in `Terminal.writeHistory()` so each segment is its own `displayBuffer` / `historyBuffer` entry; (2) added `this.term.isHistoryMode` guard before the editor block in `handleKey()` to block editor input during history mode; (3) removed redundant `this.term.refresh()` from the `appState.on('changed')` handler, leaving only `this.redraw()`. Added 6 tests in `test/terminal.spec.ts` covering multi-line split and edge cases. Added `testDisplayBuffer` getter to `Terminal` for test access. All 230 tests pass.
+- Files: `src/terminal.ts`, `src/ClaudeCli.ts`, `test/terminal.spec.ts`
+- Decisions: `testDisplayBuffer` getter added to Terminal to expose private `displayBuffer` for tests without changing production access patterns. Tests mock `process.stdout.write` to suppress noise from the non-alt-buffer screen write path. History mode guard test skipped (not testable without a ClaudeCli harness, per prompt qualifier).
+- Next: Phase 2 (push branch + PR with Closes #161)
+
+### 06:50 - investigation/rendering-duplication (#161)
+
+- Did: Investigated rendering duplication symptoms. Read all core rendering files (TerminalRenderer, terminal, Layout, Viewport, Screen, HistoryViewport, ClaudeCli, AppState, renderer). Identified 9 bugs across the rendering pipeline. Wrote investigation report to fleet investigations directory.
+- Files: (no code changes, investigation only)
+- Decisions: Primary bug is embedded newlines in displayBuffer entries breaking the renderer's row structure. Secondary bugs: editor accepting input during history mode, double render on AppState change, ANSI state leak in wrapLine, prepareEditor column mismatch, flushHistory without sync protocol.
+- Next: Fix implementation per suggested order in report (Bug 1 embedded newlines first, Bug 2 history input guard, Bug 3 double render)
+
+### 06:23 - release/publish (1.0.0-alpha.72)
+
+- Did: Published GitHub release 1.0.0-alpha.72 (pre-release); npm-publish workflow succeeded; @shellicar/claude-cli@1.0.0-alpha.72 live on npm
+- Files: (no code changes)
+- Decisions: Auto-generated notes accepted; milestone 1.0 left open (pre-release series)
+- Next: Nothing remaining for this release
+
 ### 06:12 - release/version-bump (1.0.0-alpha.72)
 
 - Did: Bumped version to 1.0.0-alpha.72, updated CHANGELOG.md with 12 commits of rendering pipeline and scrollback changes, created PR shellicar/claude-cli#160 with auto-merge enabled

src/ClaudeCli.ts

@@ -643,6 +643,11 @@ export class ClaudeCli {
       return;
     }
 
+    // Block editor input during history mode; navigation keys are handled above.
+    if (this.term.isHistoryMode) {
+      return;
+    }
+
     switch (key.type) {
       case 'ctrl+d': {
         if (this.prompts.isOtherMode) {
@@ -1030,7 +1035,6 @@ export class ClaudeCli {
       }, 300);
     });
     this.appState.on('changed', () => {
-      this.term.refresh();
       this.redraw();
     });
 

src/terminal.ts

@@ -70,6 +70,11 @@ export class Terminal {
     return this.historyViewport.mode === 'history';
   }
 
+  /** Exposed for testing only. Do not use in production code. */
+  public get testDisplayBuffer(): readonly string[] {
+    return this.displayBuffer;
+  }
+
   public scrollHistoryPageUp(): void {
     this.historyViewport.pageUp();
   }
@@ -398,14 +403,21 @@ export class Terminal {
   }
 
   private writeHistory(line: string): void {
+    const segments = line.split('\n');
     if (this._paused) {
-      this.pauseBuffer.push(line);
+      for (const segment of segments) {
+        this.pauseBuffer.push(segment);
+      }
       return;
     }
-    this.displayBuffer.push(line);
+    for (const segment of segments) {
+      this.displayBuffer.push(segment);
+    }
     if (this.inAltBuffer) {
       // Accumulate in memory; re-render zone (status may have changed)
-      this.historyBuffer.push(line);
+      for (const segment of segments) {
+        this.historyBuffer.push(segment);
+      }
       this.renderZone();
     } else {
       // Main buffer (startup messages, post-exit): write directly

test/terminal.spec.ts

@@ -0,0 +1,56 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { AppState } from '../src/AppState.js';
+import { AttachmentStore } from '../src/AttachmentStore.js';
+import { CommandMode } from '../src/CommandMode.js';
+import { Terminal } from '../src/terminal.js';
+
+function makeTerminal(): Terminal {
+  return new Terminal(new AppState(), null, new AttachmentStore(), new CommandMode());
+}
+
+describe('Terminal.writeHistory newline splitting', () => {
+  beforeEach(() => {
+    vi.spyOn(process.stdout, 'write').mockReturnValue(true);
+  });
+
+  afterEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  it('single-line input produces one displayBuffer entry', () => {
+    const term = makeTerminal();
+    term.info('hello');
+    expect(term.testDisplayBuffer).toEqual(['hello']);
+  });
+
+  it('multi-line input produces separate displayBuffer entries per line', () => {
+    const term = makeTerminal();
+    term.info('line one\nline two');
+    expect(term.testDisplayBuffer).toEqual(['line one', 'line two']);
+  });
+
+  it('three-line input produces three displayBuffer entries', () => {
+    const term = makeTerminal();
+    term.info('a\nb\nc');
+    expect(term.testDisplayBuffer).toEqual(['a', 'b', 'c']);
+  });
+
+  it('consecutive newlines preserve empty entries', () => {
+    const term = makeTerminal();
+    term.info('before\n\nafter');
+    expect(term.testDisplayBuffer).toEqual(['before', '', 'after']);
+  });
+
+  it('trailing newline produces a trailing empty entry', () => {
+    const term = makeTerminal();
+    term.info('line\n');
+    expect(term.testDisplayBuffer).toEqual(['line', '']);
+  });
+
+  it('multiple info calls accumulate correctly', () => {
+    const term = makeTerminal();
+    term.info('first');
+    term.info('second\nthird');
+    expect(term.testDisplayBuffer).toEqual(['first', 'second', 'third']);
+  });
+});