diff --git a/tests/support/collaboration.ts b/tests/support/collaboration.ts
new file mode 100644
index 000000000..459098ed0
--- /dev/null
+++ b/tests/support/collaboration.ts
@@ -0,0 +1,76 @@
+import type { PeerManager, RadiclePeer } from "@tests/support/peerManager.js";
+
+import * as Fs from "node:fs/promises";
+import * as Path from "node:path";
+
+import * as issue from "@tests/support/cobs/issue.js";
+import * as patch from "@tests/support/cobs/patch.js";
+import { defaultConfig, gitOptions } from "@tests/support/fixtures.js";
+import { createRepo } from "@tests/support/repo.js";
+
+// Bob maintains the repo; eve is connected to him and can clone it, but isn't
+// a delegate.
+export async function createCollaborators(peerManager: PeerManager) {
+  const bob = await peerManager.createPeer({
+    name: "bob",
+    gitOptions: gitOptions["bob"],
+  });
+  await bob.startNode();
+  const eve = await peerManager.createPeer({
+    name: "eve",
+    gitOptions: gitOptions["eve"],
+  });
+  await eve.startNode({
+    node: { ...defaultConfig.node, connect: [bob.address], alias: "eve" },
+  });
+  return { bob, eve };
+}
+
+// A repo with one file, one issue and one patch, all by `peer`.
+export async function createProject(peer: RadiclePeer, name = "project") {
+  const { rid, repoFolder } = await createRepo(peer, { name });
+  const file = Path.join(repoFolder, "notes.txt");
+  await Fs.writeFile(file, "one\ntwo\nthree\nfour\nfive\n");
+  await peer.git(["add", "."], { cwd: repoFolder });
+  await peer.git(["commit", "-m", "Add notes"], { cwd: repoFolder });
+  await peer.git(["push", "rad", "main"], { cwd: repoFolder });
+  const issueId = await issue.create(
+    peer,
+    "The notes are too quiet",
+    "Nobody reads them.",
+    [],
+    { cwd: repoFolder },
+  );
+  const patchId = await patch.create(
+    peer,
+    ["Shout the third line"],
+    "feature/shout",
+    () => Fs.writeFile(file, "one\ntwo\nTHREE\nfour\nfive\n"),
+    [],
+    { cwd: repoFolder },
+  );
+  return { rid, repoFolder, issueId, patchId };
+}
+
+export async function clone(peer: RadiclePeer, rid: string) {
+  await peer.rad(["clone", rid], { cwd: peer.checkoutPath });
+}
+
+// Resolves once `peer` has fetched `remote`'s changes to the COB `cobId`.
+export async function waitForCobFrom(
+  peer: RadiclePeer,
+  remote: RadiclePeer,
+  rid: string,
+  cobId: string,
+) {
+  await peer.waitForEvent(
+    event =>
+      event.type === "refsFetched" &&
+      event.rid === rid &&
+      event.remote === remote.nodeId &&
+      event.updated.some(update =>
+        Object.values(update).some(ref => ref.name.endsWith(`/${cobId}`)),
+      ),
+    15_000,
+  );
+}
diff --git a/tests/support/fixtures.ts b/tests/support/fixtures.ts
index d8f6d2df3..54759b1a4 100644
--- a/tests/support/fixtures.ts
+++ b/tests/support/fixtures.ts
@@ -173,9 +173,9 @@ const reloading = new WeakSet<Page>();
 const tearingDown = new WeakSet<Page>();
 
 // WebKit reports a fetch that was cancelled because the page went away as an
-// access control failure.
+// access control failure, or as a failed load.
 function isCancelledFetch(error: Error) {
-  return /Fetch API cannot load .* due to access control checks/.test(
+  return /Fetch API cannot load .* due to access control checks|Load failed/.test(
     error.message + error.stack,
   );
 }
@@ -192,6 +192,20 @@ export async function reload(page: Page) {
   }
 }
 
+// Runs `action` and waits for the backend command it sends to finish. The UI
+// often updates before the write lands, and a reload would cancel it.
+export async function waitForCommand(
+  page: Page,
+  command: string,
+  action: () => Promise<void>,
+) {
+  const response = page.waitForResponse(
+    response => new URL(response.url()).pathname === `/${command}`,
+  );
+  await action();
+  await response;
+}
+
 // Call before the first `page.goto`.
 export async function useBackend(page: Page, peer: RadiclePeer) {
   await page.addInitScript(port => {