chat-messages: add timeline module with builder, grouping, items, and rendering.

surfsense_web/features/chat-messages/timeline/subagent-rename.ts

@@ -0,0 +1,47 @@
+import type { TimelineItem, ToolCallItem } from "./types";
+
+function asNonEmptyString(v: unknown): string | undefined {
+	return typeof v === "string" && v.trim().length > 0 ? v.trim() : undefined;
+}
+
+/**
+ * Title-case a subagent identifier:
+ *   "notion"        → "Notion"
+ *   "doc_research"  → "Doc Research"
+ *   "ux-review"     → "Ux Review"
+ */
+export function titleCaseSubagent(raw: string): string {
+	return raw
+		.split(/[\s_-]+/)
+		.filter(Boolean)
+		.map((part) => part.charAt(0).toUpperCase() + part.slice(1))
+		.join(" ");
+}
+
+/**
+ * Display title for a tool-call item. For the ``task`` delegation
+ * primitive, substitute ``args.subagent_type`` (e.g. "Notion" instead
+ * of the generic "Task" label). Returns ``undefined`` if no rename
+ * applies — caller falls back to ``getToolDisplayName(toolName)``.
+ */
+export function resolveSubagentTitle(item: ToolCallItem): string | undefined {
+	if (item.toolName !== "task") return undefined;
+	const subagent = asNonEmptyString(item.args?.subagent_type);
+	return subagent ? titleCaseSubagent(subagent) : undefined;
+}
+
+/**
+ * Unified title resolver for any timeline item. Reasoning items use
+ * their own ``title``; tool-call items try the subagent rename first,
+ * then fall back to the resolver passed in (typically
+ * ``getToolDisplayName``).
+ *
+ * Pure: no React, no I/O. Trivially testable.
+ */
+export function resolveItemTitle(
+	item: TimelineItem,
+	getToolDisplayName: (toolName: string) => string
+): string {
+	if (item.kind === "reasoning") return item.title;
+	return resolveSubagentTitle(item) ?? getToolDisplayName(item.toolName);
+}