feat: initial Lam Agent extension (#1)

src/lib/utils.ts

@@ -0,0 +1,56 @@
+/** Small pure helpers shared across the extension. Kept dependency-free so they are trivial to test. */
+
+/**
+ * Collapses whitespace and clips to `max` characters, adding an ellipsis when clipped.
+ * Used for list rows and session titles, where a stray newline would break the layout.
+ */
+export function truncate(text: string, max: number): string {
+  const collapsed = text.replace(/\s+/g, " ").trim();
+  if (collapsed.length <= max) return collapsed;
+  return `${collapsed.slice(0, Math.max(0, max - 1)).trimEnd()}…`;
+}
+
+/** "just now", "12m ago", "3h ago", then an absolute date once it is older than a day. */
+export function formatRelativeTime(timestamp: number, now: number = Date.now()): string {
+  const deltaSeconds = Math.round((now - timestamp) / 1000);
+
+  if (!Number.isFinite(deltaSeconds) || deltaSeconds < 0) return "just now";
+  if (deltaSeconds < 45) return "just now";
+
+  const minutes = Math.round(deltaSeconds / 60);
+  if (minutes < 60) return `${minutes}m ago`;
+
+  const hours = Math.round(minutes / 60);
+  if (hours < 24) return `${hours}h ago`;
+
+  const days = Math.round(hours / 24);
+  if (days < 7) return `${days}d ago`;
+
+  return new Date(timestamp).toLocaleDateString(undefined, { month: "short", day: "numeric" });
+}
+
+/** Pulls a human-readable message out of anything that can be thrown. */
+export function errorMessage(error: unknown): string {
+  if (error instanceof Error) return error.message;
+  if (typeof error === "string") return error;
+  try {
+    return JSON.stringify(error);
+  } catch {
+    return String(error);
+  }
+}
+
+/** True when a rejected promise came from an AbortController rather than a real failure. */
+export function isAbortError(error: unknown): boolean {
+  return error instanceof Error && (error.name === "AbortError" || error.message.includes("aborted"));
+}
+
+/**
+ * Builds the first line of a prompt into a session title.
+ * Prompt text often starts with markdown decoration, which reads badly in a list row.
+ */
+export function titleFromPrompt(prompt: string, max: number): string {
+  const firstLine = prompt.split("\n").find((line) => line.trim().length > 0) ?? prompt;
+  const cleaned = firstLine.replace(/^[#>*\-\s]+/, "").trim();
+  return truncate(cleaned || "New chat", max);
+}