fix(web): align session search contracts

packages/host/apiproxy/src/api/session-search.ts

@@ -0,0 +1,22 @@
+/** Maximum number of sessions returned by one sidebar search. */
+export const SESSION_SEARCH_RESULT_LIMIT = 20
+
+/** Maximum snippet length in Unicode code points. */
+export const SESSION_SEARCH_SNIPPET_MAX_CODE_POINTS = 240
+
+/**
+ * Return the longest prefix containing at most `maximum` Unicode code points.
+ * @param value - text to bound.
+ * @param maximum - non-negative code-point limit.
+ * @returns `value` unchanged when it fits, otherwise a code-point-safe prefix.
+ */
+export function truncateUnicodeCodePoints(value: string, maximum: number): string {
+  let count = 0
+  let end = 0
+  for (const codePoint of value) {
+    if (count === maximum) return value.slice(0, end)
+    count++
+    end += codePoint.length
+  }
+  return value
+}