Prepare consistent Chunk sizes and fresh Fast Fetch integration

utils/flyio/generate_setupuri.test.ts

@@ -1,6 +1,7 @@
 import {
   decodeSettingsFromSetupURI,
   DEFAULT_SETTINGS,
+  PREFERRED_SETTING_SELF_HOSTED,
 } from "../setup/livesync-commonlib.ts";
 
 function assert(condition: unknown, message: string): asserts condition {
@@ -9,8 +10,14 @@ function assert(condition: unknown, message: string): asserts condition {
 
 Deno.test("generates a current self-hosted Setup URI through the published Commonlib contract", async () => {
   const scriptPath = new URL("./generate_setupuri.ts", import.meta.url);
+  const candidateConfig = Deno.env.get("LIVESYNC_TEST_COMMONLIB_CONFIG");
   const command = new Deno.Command(Deno.execPath(), {
-    args: ["run", "-A", scriptPath.pathname],
+    args: [
+      "run",
+      "-A",
+      ...(candidateConfig ? ["--config", candidateConfig, "--no-lock"] : []),
+      scriptPath.pathname,
+    ],
     env: {
       hostname: "https://couch.example.test",
       username: "alice",
@@ -38,7 +45,9 @@ Deno.test("generates a current self-hosted Setup URI through the published Commo
   const recoveryCode = stdout.match(/sls-id-v1:[0-9a-f]{64}/u)?.[0];
   assert(recoveryCode, "the generator did not print an ID recovery code");
   assert(
-    (effectiveSettings as typeof effectiveSettings & { idDerivationKey?: string }).idDerivationKey ===
+    (effectiveSettings as typeof effectiveSettings & {
+      idDerivationKey?: string;
+    }).idDerivationKey ===
       recoveryCode.slice("sls-id-v1:".length),
     "the CouchDB Setup URI did not contain the generated ID key",
   );
@@ -47,8 +56,9 @@ Deno.test("generates a current self-hosted Setup URI through the published Commo
     "the CouchDB Setup URI left the imported device unconfigured",
   );
   assert(
-    effectiveSettings.customChunkSize === 60,
-    "the Setup URI did not use the current self-hosted chunk-size recommendation",
+    effectiveSettings.customChunkSize ===
+      PREFERRED_SETTING_SELF_HOSTED.customChunkSize,
+    "the Setup URI did not use the self-hosted chunk-size preference from Commonlib",
   );
   assert(
     effectiveSettings.chunkSplitterVersion === "v3-rabin-karp",