fix: emoji text wrapping crash in pi-tui

Fixed crash when rendering text containing emojis followed by long content.
The breakLongWord function was iterating over UTF-16 code units instead of
grapheme clusters, causing emojis (surrogate pairs) to be miscounted during
line wrapping. Now uses Intl.Segmenter to properly handle multi-codepoint
characters.

fuck.txt

@@ -0,0 +1,12 @@
+↑21 ↓442 R12k W10k $0.048 3.7%                                  claude-sonnet-4-5file:///opt/homebrew/lib/node_modules/@mariozechner/pi-coding-agent/node_modules/@mariozechner/pi-tui/dist/tui.js:174
+                throw new Error(`Rendered line ${i} exceeds terminal width\n\n${newLines[i]}`);
+                ^
+
+Error: Rendered line 160 exceeds terminal width
+
+ 😂\n\n[2025-11-21T21-45-04-863Z_b85e1b94-c1f2-4592-8521-b36cb24f93e7.html](https:
+    at TUI.doRender (file:///opt/homebrew/lib/node_modules/@mariozechner/pi-coding-agent/node_modules/@mariozechner/pi-tui/dist/tui.js:174:23)
+    at file:///opt/homebrew/lib/node_modules/@mariozechner/pi-coding-agent/node_modules/@mariozechner/pi-tui/dist/tui.js:68:18
+    at process.processTicksAndRejections (node:internal/process/task_queues:85:11)
+
+Node.js v23.4.0

packages/coding-agent/CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Fixed
 
+- **Emoji Text Wrapping Crash**: Fixed crash when rendering text containing emojis (e.g., 😂) followed by long content like URLs. The `breakLongWord` function in `pi-tui` was iterating over UTF-16 code units instead of grapheme clusters, causing emojis (which are surrogate pairs) to be miscounted during line wrapping. Now uses `Intl.Segmenter` to properly handle multi-codepoint characters.
 - **Footer Cost Display**: Added `$` prefix to cost display in footer. Now shows `$0.078` instead of `0.078`. ([#53](https://github.com/badlogic/pi-mono/issues/53))
 
 ## [0.9.3] - 2025-11-24

packages/tui/src/utils.ts

@@ -203,33 +203,60 @@ function wrapSingleLine(line: string, width: number): string[] {
 	return wrapped.length > 0 ? wrapped : [""];
 }
 
+// Grapheme segmenter for proper Unicode iteration (handles emojis, etc.)
+const segmenter = new Intl.Segmenter();
+
 function breakLongWord(word: string, width: number, tracker: AnsiCodeTracker): string[] {
 	const lines: string[] = [];
 	let currentLine = tracker.getActiveCodes();
 	let currentWidth = 0;
+
+	// First, separate ANSI codes from visible content
+	// We need to handle ANSI codes specially since they're not graphemes
 	let i = 0;
+	const segments: Array<{ type: "ansi" | "grapheme"; value: string }> = [];
 
 	while (i < word.length) {
 		const ansiResult = extractAnsiCode(word, i);
 		if (ansiResult) {
-			currentLine += ansiResult.code;
-			tracker.process(ansiResult.code);
+			segments.push({ type: "ansi", value: ansiResult.code });
 			i += ansiResult.length;
+		} else {
+			// Find the next ANSI code or end of string
+			let end = i;
+			while (end < word.length) {
+				const nextAnsi = extractAnsiCode(word, end);
+				if (nextAnsi) break;
+				end++;
+			}
+			// Segment this non-ANSI portion into graphemes
+			const textPortion = word.slice(i, end);
+			for (const seg of segmenter.segment(textPortion)) {
+				segments.push({ type: "grapheme", value: seg.segment });
+			}
+			i = end;
+		}
+	}
+
+	// Now process segments
+	for (const seg of segments) {
+		if (seg.type === "ansi") {
+			currentLine += seg.value;
+			tracker.process(seg.value);
 			continue;
 		}
 
-		const char = word[i];
-		const charWidth = visibleWidth(char);
+		const grapheme = seg.value;
+		const graphemeWidth = visibleWidth(grapheme);
 
-		if (currentWidth + charWidth > width) {
+		if (currentWidth + graphemeWidth > width) {
 			lines.push(currentLine);
 			currentLine = tracker.getActiveCodes();
 			currentWidth = 0;
 		}
 
-		currentLine += char;
-		currentWidth += charWidth;
-		i++;
+		currentLine += grapheme;
+		currentWidth += graphemeWidth;
 	}
 
 	if (currentLine) {