docs(hopper): clarify realpath fallback scope

Closes #642

src/hopper/HopperTargetLease.ts

@@ -35,6 +35,12 @@ export const acquireHopperTargetLease = async (input: {
 }): Promise<HopperTargetLeaseAcquisition> => {
   const directory = input.directory ?? leaseDirectory;
   await ensureLeaseDirectory(directory);
+  // The normal Hopper path supplies a readable canonical target from
+  // `parseBinaryTarget`. This extra `realpath` also canonicalizes direct
+  // callers and may fail if the filesystem changes before lease acquisition.
+  // Any failure falls back to a lexical absolute path because this value only
+  // keys coordination and never authorizes access. The fallback discards the
+  // filesystem error and can let aliases of the same target take separate leases.
   const targetPath = await realpath(input.targetPath).catch(() =>
     resolve(input.targetPath),
   );