feat: add xterm-zerolag-input standalone library

Extract Claudeman's local echo overlay into a reusable xterm.js addon at packages/xterm-zerolag-input/. Provides instant keystroke feedback via a DOM overlay, eliminating perceived input latency over high-RTT connections (SSH, mobile, cloud IDEs). - Zero dependencies, compatible with xterm v5.x and @xterm/xterm v5.4+ - Configurable prompt detection (character, regex, or custom function) - Flushed text tracking for tab-switch / deferred echo scenarios - Per-character grid-aligned rendering matching xterm's canvas output - 56 tests passing (prompt finder, overlay renderer, full addon lifecycle) - Dual CJS/ESM build with full TypeScript declarations Claudeman source is unchanged — migration to consume this lib is a separate follow-up. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-10-10 09:19:42 +02:00 · 2026-02-22 10:14:37 +01:00
parent 4aa38c1bbb
commit d14ac9de65
16 changed files with 2178 additions and 0 deletions
@@ -0,0 +1,77 @@
+import type { XtermTerminal, PromptFinder, PromptPosition } from './types.js';
+
+/**
+ * Find the prompt in the terminal buffer using the configured strategy.
+ * Scans bottom-up through the viewport to find the most recent prompt.
+ *
+ * @returns The prompt position (viewport-relative), or `null` if not found.
+ */
+export function findPrompt(
+    terminal: XtermTerminal,
+    finder: PromptFinder,
+): PromptPosition | null {
+    try {
+        const buffer = terminal.buffer.active;
+        const viewportTop = buffer.viewportY;
+
+        switch (finder.type) {
+            case 'character': {
+                for (let row = terminal.rows - 1; row >= 0; row--) {
+                    const line = buffer.getLine(viewportTop + row);
+                    if (!line) continue;
+                    const text = line.translateToString(true);
+                    const idx = text.lastIndexOf(finder.char);
+                    if (idx >= 0) return { row, col: idx };
+                }
+                return null;
+            }
+
+            case 'regex': {
+                for (let row = terminal.rows - 1; row >= 0; row--) {
+                    const line = buffer.getLine(viewportTop + row);
+                    if (!line) continue;
+                    const text = line.translateToString(true);
+                    const match = text.match(finder.pattern);
+                    if (match) {
+                        const col = match.index ?? 0;
+                        return { row, col };
+                    }
+                }
+                return null;
+            }
+
+            case 'custom':
+                return finder.find(terminal);
+
+            default:
+                return null;
+        }
+    } catch {
+        return null;
+    }
+}
+
+/**
+ * Read text after the prompt position on the same line.
+ *
+ * @param terminal - The xterm.js terminal instance
+ * @param prompt - The prompt position in the viewport
+ * @param offset - Characters to skip after the prompt marker (e.g., 2 for "> ")
+ * @returns The text after the prompt, trimmed. Empty string if nothing found.
+ */
+export function readTextAfterPrompt(
+    terminal: XtermTerminal,
+    prompt: PromptPosition,
+    offset: number,
+): string {
+    try {
+        const buffer = terminal.buffer.active;
+        const absRow = buffer.viewportY + prompt.row;
+        const line = buffer.getLine(absRow);
+        if (!line) return '';
+        const lineText = line.translateToString(true);
+        return lineText.slice(prompt.col + offset).trimEnd();
+    } catch {
+        return '';
+    }
+}