test(cli): tolerate transient incomplete TUI frames

packages/cli/src/__tests__/pi-tui-runner.test.ts

@@ -55,7 +55,7 @@ import { BUSY_SPINNER_FRAMES } from '../tui-attention.js';
 import {
   assertBottomPickerPlacement,
   FakeTerminal,
-  inputSurfaceRows,
+  findInputSurfaceRows,
   latestPlainLineContaining,
   plainTerminalOutput,
   WAIT_BUDGET_MS,
@@ -5476,7 +5476,7 @@ describe('Maka Pi TUI runner', () => {
     // Sentinel render: a wrongly-opened picker would be on screen by the time
     // the typed char paints.
     terminal.input('z');
-    await waitFor(() => editorInputText(terminal).endsWith('z'));
+    await waitFor(() => editorInputText(terminal)?.endsWith('z') === true);
     assert.equal(plainTerminalOutput(terminal.screenOutput()).includes('回到选定轮次'), false);
 
     exitMaka(terminal);
@@ -6489,9 +6489,11 @@ function bellCount(terminal: FakeTerminal): number {
   return terminal.writes.filter((write) => write === '\x07').length;
 }
 
-function editorInputText(terminal: FakeTerminal): string {
+function editorInputText(terminal: FakeTerminal): string | undefined {
   const lines = plainTerminalOutput(terminal.screenOutput()).split(/\r?\n/);
-  const [topEditorBorderIndex, bottomEditorBorderIndex] = inputSurfaceRows(lines);
+  const inputRows = findInputSurfaceRows(lines);
+  if (!inputRows) return undefined;
+  const [topEditorBorderIndex, bottomEditorBorderIndex] = inputRows;
   return lines
     .slice(topEditorBorderIndex + 1, bottomEditorBorderIndex)
     .join('\n')

packages/cli/src/__tests__/tui-terminal-mock.test.ts

@@ -0,0 +1,12 @@
+import assert from 'node:assert/strict';
+import { test } from 'node:test';
+import { findInputSurfaceRows, inputSurfaceRows } from './tui-terminal-mock.js';
+
+test('input surface lookup distinguishes an intermediate frame from a settled frame', () => {
+  const intermediate = ['────────────────'];
+  const settled = ['────────────────', 'draft', '────────────────'];
+
+  assert.equal(findInputSurfaceRows(intermediate), undefined);
+  assert.deepEqual(findInputSurfaceRows(settled), [0, 2]);
+  assert.throws(() => inputSurfaceRows(intermediate));
+});

packages/cli/src/__tests__/tui-terminal-mock.ts

@@ -67,17 +67,23 @@ export function plainTerminalOutput(output: string): string {
     .replace(/\x1b\[[0-9;?]*[ -/]*[@-~]/g, '');
 }
 
-export function inputSurfaceRows(lines: readonly string[]): [number, number] {
+export function findInputSurfaceRows(lines: readonly string[]): [number, number] | undefined {
   const editorBorderIndexes = lines
     .map((line, index) => (/^─+$/.test(line) ? index : -1))
     .filter((index) => index >= 0);
-  assert.ok(editorBorderIndexes.length >= 2);
+  if (editorBorderIndexes.length < 2) return undefined;
   return [
     editorBorderIndexes[editorBorderIndexes.length - 2]!,
     editorBorderIndexes[editorBorderIndexes.length - 1]!,
   ];
 }
 
+export function inputSurfaceRows(lines: readonly string[]): [number, number] {
+  const rows = findInputSurfaceRows(lines);
+  assert.ok(rows, 'expected a settled input surface with top and bottom editor borders');
+  return rows;
+}
+
 /**
  * The slash-autocomplete suggestion rows on the input surface: the contiguous
  * `/command` lines sitting immediately above the editor's top border. The
@@ -89,11 +95,9 @@ export function inputSurfaceRows(lines: readonly string[]): [number, number] {
  */
 export function autocompleteSuggestionLines(lines: readonly string[]): readonly string[] {
   if (!lines.some((line) => line.includes('→'))) return [];
-  const editorBorders = lines
-    .map((line, index) => (/^─+$/.test(line) ? index : -1))
-    .filter((index) => index >= 0);
-  if (editorBorders.length < 2) return [];
-  const editorTopBorder = editorBorders[editorBorders.length - 2]!;
+  const inputRows = findInputSurfaceRows(lines);
+  if (!inputRows) return [];
+  const [editorTopBorder] = inputRows;
   let start = editorTopBorder;
   while (start > 0 && /\/\w/.test(lines[start - 1]!)) start -= 1;
   return lines.slice(start, editorTopBorder);