fix(tui): measure display width so CJK output cannot overflow the terminal

.pi/extensions/_shared/width.test.ts

@@ -59,3 +59,19 @@ describe("truncateLineToWidth", () => {
     void honey; // keep import shape parity with the tracker
   });
 });
+
+describe("wide characters", () => {
+  it("counts CJK and fullwidth characters as two columns", () => {
+    expect(visibleWidth("中文")).toBe(4);
+    expect(visibleWidth("a中b")).toBe(4);
+    expect(visibleWidth("（全角）")).toBe(8);
+  });
+  it("counts combining marks as zero columns", () => {
+    expect(visibleWidth("é")).toBe(1);
+  });
+  it("truncates CJK text to the column budget", () => {
+    const out = truncateLineToWidth("研究报告：仓库实际位于子目录", 10);
+    expect(visibleWidth(out)).toBeLessThanOrEqual(10);
+    expect(stripAnsi(out).endsWith("…")).toBe(true);
+  });
+});

.pi/extensions/_shared/width.ts

@@ -20,12 +20,48 @@ export function stripAnsi(s: string): string {
   return s.replace(SGR_RE, "").replace(OSC_RE, "");
 }
 
-// Approximation: ANSI-stripped char count (treats every visible char as width
-// 1). Exact for ASCII / Latin / single-cell glyphs the tracker and status
-// widgets emit. Wide CJK or emoji *under*count here, so callers should leave a
-// small safety margin (see terminalColumns/SAFETY_MARGIN).
+// Terminal column width of one code point: 0 for combining marks and
+// zero-width characters, 2 for East Asian Wide/Fullwidth characters and
+// emoji, 1 otherwise. Mirrors wcwidth closely enough for pi-tui's
+// line-width check; CJK text counted as 1 column per char overflowed the
+// terminal and crashed pi.
+export function charWidth(ch: string): number {
+  const cp = ch.codePointAt(0) ?? 0;
+  if (cp === 0 || cp < 0x20 || (cp >= 0x7f && cp < 0xa0)) return 0;
+  if (
+    (cp >= 0x0300 && cp <= 0x036f) || // combining diacritics
+    (cp >= 0x200b && cp <= 0x200f) || // zero-width space/joiners, marks
+    (cp >= 0xfe00 && cp <= 0xfe0f) || // variation selectors
+    (cp >= 0xe0100 && cp <= 0xe01ef)
+  ) {
+    return 0;
+  }
+  if (
+    (cp >= 0x1100 && cp <= 0x115f) || // Hangul Jamo
+    (cp >= 0x2e80 && cp <= 0x303e) || // CJK radicals, punctuation
+    (cp >= 0x3041 && cp <= 0x33ff) || // kana, CJK symbols
+    (cp >= 0x3400 && cp <= 0x4dbf) || // CJK Ext A
+    (cp >= 0x4e00 && cp <= 0x9fff) || // CJK Unified
+    (cp >= 0xa000 && cp <= 0xa4cf) || // Yi
+    (cp >= 0xac00 && cp <= 0xd7a3) || // Hangul syllables
+    (cp >= 0xf900 && cp <= 0xfaff) || // CJK compatibility
+    (cp >= 0xfe30 && cp <= 0xfe4f) || // CJK compatibility forms
+    (cp >= 0xff00 && cp <= 0xff60) || // fullwidth forms
+    (cp >= 0xffe0 && cp <= 0xffe6) ||
+    (cp >= 0x1f300 && cp <= 0x1f64f) || // emoji
+    (cp >= 0x1f900 && cp <= 0x1f9ff) ||
+    (cp >= 0x20000 && cp <= 0x3fffd) // CJK Ext B+
+  ) {
+    return 2;
+  }
+  return 1;
+}
+
+// Display width of an ANSI-stripped string, in terminal columns.
 export function visibleWidth(s: string): number {
-  return [...stripAnsi(s)].length;
+  let w = 0;
+  for (const ch of stripAnsi(s)) w += charWidth(ch);
+  return w;
 }
 
 // Truncate `line` so its visible width fits `maxWidth`. ANSI escapes are
@@ -57,17 +93,20 @@ export function truncateLineToWidth(line: string, maxWidth: number, ellipsis = "
         continue;
       }
     }
-    if (visible >= cutAt) break;
-    out += ch;
-    visible += 1;
-    i += 1;
+    const cp = line.codePointAt(i) ?? 0;
+    const glyph = String.fromCodePoint(cp);
+    const w = charWidth(glyph);
+    if (visible + w > cutAt) break;
+    out += glyph;
+    visible += w;
+    i += glyph.length;
   }
   return out + ellipsis + "\x1b[0m";
 }
 
-// Current terminal width, with a small safety margin to absorb wide Unicode
-// chars that visibleWidth's char-count approximation under-measures. Falls
-// back to `fallback` columns when stdout isn't a TTY (headless runs).
+// Current terminal width, with a small safety margin for glyphs whose
+// rendered width differs from charWidth's table (ambiguous-width symbols,
+// newer emoji). Falls back to `fallback` columns when stdout isn't a TTY.
 const SAFETY_MARGIN = 2;
 export function terminalColumns(fallback = 80): number {
   const c = (process.stdout && (process.stdout as any).columns) | 0;

.pi/extensions/subagent/cjk-width-repro.test.ts

@@ -0,0 +1,36 @@
+import { describe, it, expect } from "vitest";
+import { makeComponent } from "./index.ts";
+
+// Independent of the code under test: CJK ideographs, CJK punctuation and
+// fullwidth forms take two terminal columns, everything used here takes one.
+const columns = (s: string) =>
+  [...s.replace(/\x1b\[[0-9;]*[a-zA-Z]/g, "")].reduce(
+    (w, ch) => w + (/[\u3000-\u303f\u4e00-\u9fff\uff00-\uff60]/.test(ch) ? 2 : 1),
+    0,
+  );
+
+// Regression for a crash with CJK sub-coder reports: the wrap measured
+// String.length, so a Chinese sentence fitting in 241 chars rendered
+// 245 columns wide at terminal width 243 and pi-tui aborted the session
+// ("Rendered line 147 exceeds terminal width (245 > 243)").
+
+const report =
+  "**直接回答**：skill 成功获取。`github.com/pans0020/research-writing` 为 404，实际仓库是 **Pans0020/opencode-skills** 的 `research-writing/` 目录（含 4 个文件：SKILL.md 24.1KB、DEPLOY.md、QUICKSTART.md、README.md）。agentskill.sh 可正常访问。";
+
+describe("CJK sub-coder report fits the pi-supplied width", () => {
+  for (const width of [243, 120, 80, 40]) {
+    it(`wraps to width ${width}`, () => {
+      const out = makeComponent(["✓ pans0020-research-writing", report, "  …"]).render(width);
+      for (const line of out) expect(columns(line)).toBeLessThanOrEqual(width - 1);
+      // No text is lost: every CJK char of the report is still present.
+      const joined = out.join("");
+      for (const ch of "直接回答成功获取实际仓库是目录可正常访问") expect(joined).toContain(ch);
+    });
+  }
+
+  it("wraps a long CJK run with no spaces", () => {
+    const out = makeComponent(["中".repeat(300)]).render(81);
+    expect(out.length).toBeGreaterThan(1);
+    for (const line of out) expect(columns(line)).toBeLessThanOrEqual(80);
+  });
+});

.pi/extensions/subagent/index.ts

@@ -9,6 +9,7 @@ import {
   type SubCoderResult,
 } from "./spawn.ts";
 import { SubCoderTracker } from "./tracker.ts";
+import { charWidth, visibleWidth } from "../_shared/width.ts";
 
 // The `dispatch` tool: the main little-coder spawns isolated child little-coder
 // sessions ("sub-coders") to research a focused question — they read the repo
@@ -256,21 +257,50 @@ function stripAnsi(text: string): string {
   return text.replace(ANSI_RE, "");
 }
 
-/** Word-wrap plain text at whitespace; assumes long tokens are pre-chunked. */
+/** Split a word into pieces no wider than maxWidth display columns. */
+function splitByWidth(word: string, maxWidth: number): string[] {
+  const pieces: string[] = [];
+  let current = "";
+  let width = 0;
+  for (const ch of word) {
+    const w = charWidth(ch);
+    if (width + w > maxWidth && current) {
+      pieces.push(current);
+      current = "";
+      width = 0;
+    }
+    current += ch;
+    width += w;
+  }
+  if (current) pieces.push(current);
+  return pieces;
+}
+
+/**
+ * Word-wrap plain text at whitespace, measuring display columns so CJK text
+ * (two columns per char, often with no spaces to break at) cannot overflow.
+ */
 function wrapPlainText(text: string, maxWidth: number): string[] {
-  if (text.length <= maxWidth) return [text];
-  const words = text.split(/\s+/);
+  if (visibleWidth(text) <= maxWidth) return [text];
+  const words = text.split(/\s+/).flatMap((word) =>
+    visibleWidth(word) > maxWidth ? splitByWidth(word, maxWidth) : [word],
+  );
   const result: string[] = [];
   let current = "";
+  let currentWidth = 0;
   for (const word of words) {
     if (!word) continue;
-    if (current.length === 0) {
+    const w = visibleWidth(word);
+    if (currentWidth === 0) {
       current = word;
-    } else if (current.length + 1 + word.length <= maxWidth) {
+      currentWidth = w;
+    } else if (currentWidth + 1 + w <= maxWidth) {
       current += " " + word;
+      currentWidth += 1 + w;
     } else {
       result.push(current);
       current = word;
+      currentWidth = w;
     }
   }
   if (current) result.push(current);
@@ -280,7 +310,7 @@ function wrapPlainText(text: string, maxWidth: number): string[] {
 /** Wrap one ANSI-aware line to width, re-applying any leading SGR prefix. */
 function wrapLine(line: string, width: number): string[] {
   const plain = stripAnsi(line);
-  if (plain.length <= width) return [line];
+  if (visibleWidth(plain) <= width) return [line];
   const { prefix } = extractAnsiPrefix(line);
   const wrappedLines = wrapPlainText(plain, width);
   return wrappedLines.map((l) => prefix + l);