fix(core): correct WAAPI rediscovery seek baselines and preview reuse invalidation

packages/cli/src/server/runtimeSource.ts

@@ -1,3 +1,4 @@
+import { createHash } from "node:crypto";
 import { existsSync, readFileSync } from "node:fs";
 import { resolve, dirname } from "node:path";
 
@@ -16,6 +17,21 @@ export async function loadRuntimeSource(): Promise<string | null> {
   return (await buildFromSource()) ?? (await getInlinedRuntime()) ?? readPrebuiltArtifact();
 }
 
+export async function loadRuntimeSourceSignature(): Promise<string | null> {
+  const source = await loadRuntimeSource();
+  if (!source) return null;
+  return createHash("sha256").update(source).digest("hex");
+}
+
+export function hashSignatureParts(parts: Array<string | null | undefined>): string {
+  const hash = createHash("sha256");
+  for (const part of parts) {
+    hash.update(part ?? "");
+    hash.update("\n--hf-signature-part--\n");
+  }
+  return hash.digest("hex");
+}
+
 // ── Strategy 1: live build from source (dev only) ──────────────────────────
 
 const ENTRY_TS = resolve(__dirname, "..", "..", "..", "core", "src", "runtime", "entry.ts");