feat(utils): add watch mode trigger detection and context extraction functions

Author: stefanoamorelli

codex-cli/src/utils/watch-mode-utils.ts

@@ -0,0 +1,63 @@
+/**
+ * Pattern to match various "AI!" style trigger comments with possible instructions
+ * This will match patterns like:
+ * - "// what does this function do, AI?"
+ * - "// change this variable name to something more precise, AI!"
+ * - "# fix this code, AI!"
+ */
+export const TRIGGER_PATTERN =
+  /\/\/\s*(.*),?\s*AI[!?]|#\s*(.*),?\s*AI[!?]|\/\*\s*(.*),?\s*AI[!?]\s*\*\//;
+
+/**
+ * Function to find all AI trigger matches in a file content
+ */
+export function findAllTriggers(content: string): Array<RegExpMatchArray> {
+  const matches: Array<RegExpMatchArray> = [];
+  const regex = new RegExp(TRIGGER_PATTERN, "g");
+
+  let match;
+  while ((match = regex.exec(content)) != null) {
+    matches.push(match);
+  }
+
+  return matches;
+}
+
+/**
+ * Function to extract context around an AI trigger
+ */
+export function extractContextAroundTrigger(
+  content: string,
+  triggerMatch: RegExpMatchArray,
+  contextSize = 15
+): { context: string; instruction: string } {
+  // Get the lines of the file
+  const lines = content.split("\n");
+
+  // Find the line number of the trigger
+  const triggerPos =
+    content.substring(0, triggerMatch.index).split("\n").length - 1;
+
+  // Calculate start and end lines for context
+  const startLine = Math.max(0, triggerPos - contextSize);
+  const endLine = Math.min(lines.length - 1, triggerPos + contextSize);
+
+  // Extract the context lines
+  const contextLines = lines.slice(startLine, endLine + 1);
+
+  // Join the context lines back together
+  const context = contextLines.join("\n");
+
+  // Extract the instruction from the capture groups
+  // The regex has 3 capture groups for different comment styles:
+  // Group 1: // instruction AI!
+  // Group 2: # instruction AI!
+  // Group 3: /* instruction AI! */
+  const instruction =
+    triggerMatch[1] ||
+    triggerMatch[2] ||
+    triggerMatch[3] ||
+    "fix or improve this code";
+
+  return { context, instruction };
+}