Initial import of LogDarioSeq baseline

Establishes version control for the personal Logseq DB fork before
starting the server-client architecture migration and domain features
described in docs/agent-guide and the approved implementation plan.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

deps/db-sync/worker/semantic_request.mjs

@@ -0,0 +1,48 @@
+const MAX_ASSET_SIZE = 100 * 1024 * 1024;
+
+function decodedBase64Size(value) {
+  if (typeof value !== "string") throw new Error("base64 asset body must be a string");
+
+  let length = 0;
+  let padding = 0;
+  let sawPadding = false;
+  for (let index = 0; index < value.length; index += 1) {
+    const character = value[index];
+    const code = value.charCodeAt(index);
+    if (code === 9 || code === 10 || code === 12 || code === 13 || code === 32) continue;
+    if (character === "=") {
+      sawPadding = true;
+      padding += 1;
+    } else {
+      const base64Character = (code >= 65 && code <= 90) ||
+        (code >= 97 && code <= 122) ||
+        (code >= 48 && code <= 57) || code === 43 || code === 47;
+      if (sawPadding || !base64Character) {
+        throw new Error("invalid base64 asset body");
+      }
+    }
+    length += 1;
+  }
+  if (length % 4 !== 0 || padding > 2) throw new Error("invalid base64 asset body");
+  return (length / 4) * 3 - padding;
+}
+
+export function semanticRequestUrl(options, baseUrl) {
+  const url = new URL(options.path, baseUrl);
+  for (const [key, value] of Object.entries(options.query ?? {})) {
+    if (value !== undefined) url.searchParams.set(key, String(value));
+  }
+  if (url.searchParams.get("encoding") === "base64") {
+    const size = decodedBase64Size(options.body);
+    if (size > MAX_ASSET_SIZE) throw new Error("decoded asset exceeds the 100MB limit");
+    url.searchParams.set("size", String(size));
+  }
+  return url;
+}
+
+export function semanticRequestBody(options, url) {
+  if (options.body === undefined) return undefined;
+  return options.rawBody || url.searchParams.get("encoding") === "base64"
+    ? options.body
+    : JSON.stringify(options.body);
+}