diff --git a/tests/browser/agent-activity.spec.mjs b/tests/browser/agent-activity.spec.mjs
index 5ae2635..17dc83b 100644
--- a/tests/browser/agent-activity.spec.mjs
+++ b/tests/browser/agent-activity.spec.mjs
@@ -1,7 +1,11 @@
 import { test, expect } from "./fixture.mjs";
 import { open } from "./timeline.mjs";
 import { finalizeEvent, generateSecretKey, getPublicKey } from "nostr-tools";
-test.use({ productionBroker: true, developmentReact: true });
+test.use({
+  productionBroker: true,
+  developmentReact: true,
+  historyCounts: { alpha: 1, beta: 1 },
+});
 
 const channelActivity = (page) =>
   page.getByRole("region", {
@@ -374,7 +378,11 @@ test("profile activity opens the exact agent and originating channel before its
 });
 
 test.describe("thread activity", () => {
-  test.use({ threadUnread: true, readState: true });
+  test.use({
+    threadUnread: true,
+    readState: true,
+    historyCounts: { alpha: 2, beta: 1 }, // Thread fixtures replace the last two Alpha rows with roots.
+  });
 
   test("thread typing uses the existing route, stays isolated, and opens channel details above the composer", async ({
     page,
diff --git a/tests/browser/appearance.spec.mjs b/tests/browser/appearance.spec.mjs
index 6ae7095..8f34a73 100644
--- a/tests/browser/appearance.spec.mjs
+++ b/tests/browser/appearance.spec.mjs
@@ -1,6 +1,7 @@
 import { test, expect } from "./fixture.mjs";
 import { open, anchor, expectAnchor } from "./timeline.mjs";
 
+test.use({ historyCounts: { alpha: 20, beta: 1 } });
 const key = "buzz-appearance.v1";
 const button = (page, name) => page.getByRole("button", { name, exact: true });
 async function settings(page) {
diff --git a/tests/browser/buzz-links.spec.mjs b/tests/browser/buzz-links.spec.mjs
index 4a4bf88..3bf3a02 100644
--- a/tests/browser/buzz-links.spec.mjs
+++ b/tests/browser/buzz-links.spec.mjs
@@ -6,6 +6,7 @@ test.use({
   readState: true,
   threadUnread: true,
   pluginFixtures: true,
+  historyCounts: { alpha: 640, beta: 1 },
 });
 const button = (page, name) => page.getByRole("button", { name, exact: true });
 const state = (page) =>
diff --git a/tests/browser/channel-opening.spec.mjs b/tests/browser/channel-opening.spec.mjs
index bd00e6c..b967c56 100644
--- a/tests/browser/channel-opening.spec.mjs
+++ b/tests/browser/channel-opening.spec.mjs
@@ -2,7 +2,11 @@ import { readFile } from "node:fs/promises";
 import { test, expect } from "./fixture.mjs";
 import { open } from "./timeline.mjs";
 
-test.use({ productionBroker: true, largeSidebar: true });
+test.use({
+  productionBroker: true,
+  largeSidebar: true,
+  historyCounts: { alpha: 20, beta: 20 },
+});
 const heads = (app, channel) =>
   app.report.queries.filter(
     ({ filter }) =>
diff --git a/tests/browser/completion-layout.spec.mjs b/tests/browser/completion-layout.spec.mjs
index 7a727a1..cd70201 100644
--- a/tests/browser/completion-layout.spec.mjs
+++ b/tests/browser/completion-layout.spec.mjs
@@ -1,5 +1,6 @@
 import { test, expect } from "./fixture.mjs";
 
+test.use({ historyCounts: { alpha: 1, beta: 0 } });
 test("completion menu stays reachable in the production channel layout", async ({
   page,
   app,
diff --git a/tests/browser/dm-labels.spec.mjs b/tests/browser/dm-labels.spec.mjs
index 63e95b9..c9f2248 100644
--- a/tests/browser/dm-labels.spec.mjs
+++ b/tests/browser/dm-labels.spec.mjs
@@ -1,7 +1,11 @@
 import { test, expect } from "./fixture.mjs";
 import { open } from "./timeline.mjs";
 
-test.use({ productionBroker: true, dmLabels: true });
+test.use({
+  productionBroker: true,
+  dmLabels: true,
+  historyCounts: { alpha: 1, beta: 1 },
+});
 
 for (const cold of [false, true]) {
   test(`DM names recover after ${cold ? "hidden channel deletion aborts a cold fetch" : "channel deletion purges loaded profiles"}`, async ({
diff --git a/tests/browser/external-links.spec.mjs b/tests/browser/external-links.spec.mjs
index 9e8dcbc..31dd8e6 100644
--- a/tests/browser/external-links.spec.mjs
+++ b/tests/browser/external-links.spec.mjs
@@ -1,6 +1,7 @@
 import { test, expect } from "./fixture.mjs";
 import { end } from "./timeline.mjs";
 
+test.use({ historyCounts: { alpha: 1, beta: 0 } });
 const github = "https://github.com/block/buzz/pull/1";
 const ordinary = "https://example.test/external-link";
 const unsupported = "https://github.com/block/buzz/blob/main/README.md";
diff --git a/tests/browser/gifs.spec.mjs b/tests/browser/gifs.spec.mjs
index fabf4e6..71d285c 100644
--- a/tests/browser/gifs.spec.mjs
+++ b/tests/browser/gifs.spec.mjs
@@ -1,6 +1,7 @@
 import { expectPhosphor } from "./phosphor.mjs";
 import { test, expect } from "./fixture.mjs";
 
+test.use({ historyCounts: { alpha: 1, beta: 0 } });
 test("relay-backed GIF tab searches KLIPY and inserts URL-only media", async ({
   page,
   app,
diff --git a/tests/browser/history-loading.spec.mjs b/tests/browser/history-loading.spec.mjs
index 3507345..1f51650 100644
--- a/tests/browser/history-loading.spec.mjs
+++ b/tests/browser/history-loading.spec.mjs
@@ -1,7 +1,10 @@
 import { test, expect } from "./fixture.mjs";
 import { open, settle } from "./timeline.mjs";
 
-test.use({ productionBroker: true });
+test.use({
+  productionBroker: true,
+  historyCounts: { alpha: 640, beta: 20 },
+});
 const history = (page) =>
   page.getByRole("region", { name: "Channel message history" });
 
diff --git a/tests/browser/layout.spec.mjs b/tests/browser/layout.spec.mjs
index f99b6ad..04a8a7c 100644
--- a/tests/browser/layout.spec.mjs
+++ b/tests/browser/layout.spec.mjs
@@ -2,6 +2,7 @@ import { test, expect } from "./fixture.mjs";
 import { settle, upper, expectAnchor } from "./timeline.mjs";
 
 // Resize tests must not enter the fixture’s deliberately held paging path.
+test.use({ historyCounts: { alpha: 640, beta: 80 } });
 const readingTest = test.extend({ tallMessages: true });
 async function expectNonPaging(page, app) {
   expect(
diff --git a/tests/browser/live-status.spec.mjs b/tests/browser/live-status.spec.mjs
index 76b43b8..5ff6080 100644
--- a/tests/browser/live-status.spec.mjs
+++ b/tests/browser/live-status.spec.mjs
@@ -1,5 +1,8 @@
 import { test, expect } from "./fixture.mjs";
-test.use({ productionBroker: true });
+test.use({
+  productionBroker: true,
+  historyCounts: { alpha: 1, beta: 1 },
+});
 test("clean pending setup stays in diagnostics and never flashes a warning during channel switches", async ({
   page,
   app,
diff --git a/tests/browser/live.spec.mjs b/tests/browser/live.spec.mjs
index c879de7..984a80a 100644
--- a/tests/browser/live.spec.mjs
+++ b/tests/browser/live.spec.mjs
@@ -1,7 +1,10 @@
 import { test, expect } from "./fixture.mjs";
 import { open, settle, upper, expectAnchor, end, anchor } from "./timeline.mjs";
 
-test.use({ productionBroker: true });
+test.use({
+  productionBroker: true,
+  historyCounts: { alpha: 640, beta: 20 },
+});
 const history = (page) =>
   page.getByRole("region", { name: "Channel message history" });
 const retry = (page) =>
diff --git a/tests/browser/membership.spec.mjs b/tests/browser/membership.spec.mjs
index f973953..fd68c52 100644
--- a/tests/browser/membership.spec.mjs
+++ b/tests/browser/membership.spec.mjs
@@ -1,7 +1,11 @@
 import { test, expect } from "./fixture.mjs";
 import { anchor, expectAnchor, settle } from "./timeline.mjs";
 
-test.use({ membershipActivity: true, productionBroker: true });
+test.use({
+  membershipActivity: true,
+  productionBroker: true,
+  historyCounts: { alpha: 640, beta: 1 },
+});
 
 // Do not let the shared fixture's legacy WebKit exception mask timeline reflow
 // errors. These journeys must preserve the reader without observer-loop errors.
diff --git a/tests/browser/navigation-groups.spec.mjs b/tests/browser/navigation-groups.spec.mjs
index 72e8266..0b4c28a 100644
--- a/tests/browser/navigation-groups.spec.mjs
+++ b/tests/browser/navigation-groups.spec.mjs
@@ -6,6 +6,7 @@ test.use({
   savedSidebar: true,
   largeSidebar: true,
   developmentReact: true,
+  historyCounts: { alpha: 1, beta: 1 },
 });
 test("Home → Messages keeps saved groups, selected channel, and scroll on every visible frame without re-decoding", async ({
   page,
diff --git a/tests/browser/navigation-join.spec.mjs b/tests/browser/navigation-join.spec.mjs
index 3daaade..03a3844 100644
--- a/tests/browser/navigation-join.spec.mjs
+++ b/tests/browser/navigation-join.spec.mjs
@@ -1,6 +1,7 @@
 import { test, expect } from "./fixture.mjs";
 import { open } from "./timeline.mjs";
 
+test.use({ historyCounts: { alpha: 640, beta: 1 } });
 const button = (page, name) => page.getByRole("button", { name, exact: true });
 const entry = (page) =>
   page.evaluate(() => history.state.buzzNavigationV1.entry);
diff --git a/tests/browser/navigation-repairs.spec.mjs b/tests/browser/navigation-repairs.spec.mjs
index 08fd321..032b4a4 100644
--- a/tests/browser/navigation-repairs.spec.mjs
+++ b/tests/browser/navigation-repairs.spec.mjs
@@ -1,6 +1,7 @@
 import { test, expect } from "./fixture.mjs";
 import { open } from "./timeline.mjs";
 
+test.use({ historyCounts: { alpha: 1, beta: 1 } });
 // Regressions independently reproduced by Pinky against the first wiring handoff.
 const button = (page, name) => page.getByRole("button", { name, exact: true });
 const entry = (page) =>
diff --git a/tests/browser/navigation-scroll-intent.spec.mjs b/tests/browser/navigation-scroll-intent.spec.mjs
index 69abfab..0041a79 100644
--- a/tests/browser/navigation-scroll-intent.spec.mjs
+++ b/tests/browser/navigation-scroll-intent.spec.mjs
@@ -2,7 +2,12 @@ import { test, expect } from "./fixture.mjs";
 import { open } from "./timeline.mjs";
 
 const button = (page, name) => page.getByRole("button", { name, exact: true });
-test.use({ largeSidebar: true, productionBroker: true, readState: true });
+test.use({
+  largeSidebar: true,
+  productionBroker: true,
+  readState: true,
+  historyCounts: { alpha: 1, beta: 1 },
+});
 
 for (const action of [
   "untouched",
diff --git a/tests/browser/navigation-sidebar.spec.mjs b/tests/browser/navigation-sidebar.spec.mjs
index 29dde65..251a75f 100644
--- a/tests/browser/navigation-sidebar.spec.mjs
+++ b/tests/browser/navigation-sidebar.spec.mjs
@@ -1,7 +1,10 @@
 import { test, expect } from "./fixture.mjs";
 import { open } from "./timeline.mjs";
 const button = (page, name) => page.getByRole("button", { name, exact: true });
-test.use({ largeSidebar: true });
+test.use({
+  largeSidebar: true,
+  historyCounts: { alpha: 1, beta: 1 },
+});
 
 test("channel navigation preserves sidebar search, DOM, group state and scroll", async ({
   page,
diff --git a/tests/browser/navigation-thread-history.spec.mjs b/tests/browser/navigation-thread-history.spec.mjs
index 1f5dc87..2137c67 100644
--- a/tests/browser/navigation-thread-history.spec.mjs
+++ b/tests/browser/navigation-thread-history.spec.mjs
@@ -1,7 +1,12 @@
 import { test, expect } from "./fixture.mjs";
 import { open } from "./timeline.mjs";
 
-test.use({ productionBroker: true, readState: true, threadUnread: true });
+test.use({
+  productionBroker: true,
+  readState: true,
+  threadUnread: true,
+  historyCounts: { alpha: 20, beta: 20 },
+});
 
 test("Back restores each thread visit before the previous channel", async ({
   page,
diff --git a/tests/browser/plugin-import.spec.mjs b/tests/browser/plugin-import.spec.mjs
index 70aed2b..7a43326 100644
--- a/tests/browser/plugin-import.spec.mjs
+++ b/tests/browser/plugin-import.spec.mjs
@@ -1,6 +1,7 @@
 import { readFile } from "node:fs/promises";
 import { test, expect } from "./fixture.mjs";
 
+test.use({ historyCounts: { alpha: 0, beta: 0 } });
 const button = (page, name) => page.getByRole("button", { name, exact: true });
 async function openPlugins(page, origin) {
   await page.goto(origin);
diff --git a/tests/browser/profiles-appearance.spec.mjs b/tests/browser/profiles-appearance.spec.mjs
index 5deeae5..a700794 100644
--- a/tests/browser/profiles-appearance.spec.mjs
+++ b/tests/browser/profiles-appearance.spec.mjs
@@ -1,6 +1,7 @@
 import { test, expect } from "./fixture.mjs";
 import { open } from "./timeline.mjs";
 
+test.use({ historyCounts: { alpha: 20, beta: 0 } });
 for (const mode of ["light", "dark"]) {
   test(`Profiles uses shared styles and host keyboard focus in ${mode} mode`, async ({
     page,
diff --git a/tests/browser/scroll.spec.mjs b/tests/browser/scroll.spec.mjs
index bc501e5..d92c9b1 100644
--- a/tests/browser/scroll.spec.mjs
+++ b/tests/browser/scroll.spec.mjs
@@ -11,6 +11,7 @@ import {
   edge,
 } from "./timeline.mjs";
 
+test.use({ historyCounts: { alpha: 640, beta: 80 } });
 // Keep non-paging reading gestures outside the unchanged near-top read zone,
 // even with a 20-row head. The cursor journey below keeps ordinary-height rows.
 const readingTest = test.extend({ tallMessages: true });
diff --git a/tests/browser/sidebar-unread.spec.mjs b/tests/browser/sidebar-unread.spec.mjs
index c5b6a24..e5fa9ff 100644
--- a/tests/browser/sidebar-unread.spec.mjs
+++ b/tests/browser/sidebar-unread.spec.mjs
@@ -11,6 +11,7 @@ test.use({
   readState: true,
   largeSidebar: true,
   sidebarUnread: true,
+  historyCounts: { alpha: 20, beta: 20 },
 });
 const sidebar = (page) =>
   page.getByRole("complementary", { name: "Channel sidebar", exact: true });
diff --git a/tests/browser/terminal.spec.mjs b/tests/browser/terminal.spec.mjs
index b8913a1..f92aa29 100644
--- a/tests/browser/terminal.spec.mjs
+++ b/tests/browser/terminal.spec.mjs
@@ -1,6 +1,7 @@
 import { test, expect } from "./fixture.mjs";
 import { open } from "./timeline.mjs";
 const button = (page, name) => page.getByRole("button", { name, exact: true });
+test.use({ historyCounts: { alpha: 1, beta: 0 } });
 test("web hides the unusable terminal and does not consume its shortcut, including re-enable", async ({
   page,
   app,
diff --git a/tests/browser/thread-unread.spec.mjs b/tests/browser/thread-unread.spec.mjs
index 384163d..760b9fc 100644
--- a/tests/browser/thread-unread.spec.mjs
+++ b/tests/browser/thread-unread.spec.mjs
@@ -5,6 +5,7 @@ test.use({
   productionBroker: true,
   readState: true,
   threadUnread: true,
+  historyCounts: { alpha: 20, beta: 1 },
   largeSidebar: true,
   pluginFixtures: true, // Observe the real navigation completion, not reply mount timing.
 });
diff --git a/tests/browser/timeline-setup.spec.mjs b/tests/browser/timeline-setup.spec.mjs
index 520a45c..aa08008 100644
--- a/tests/browser/timeline-setup.spec.mjs
+++ b/tests/browser/timeline-setup.spec.mjs
@@ -2,7 +2,10 @@ import { test, expect } from "./fixture.mjs";
 import { open, upper, anchor, expectAnchor } from "./timeline.mjs";
 
 // Reading setup must not accidentally exercise older-page loading.
-test.use({ tallMessages: true });
+test.use({
+  tallMessages: true,
+  historyCounts: { alpha: 640, beta: 1 },
+});
 const history = (page) =>
   page.getByRole("region", { name: "Channel message history" });
 
diff --git a/tests/browser/typing.spec.mjs b/tests/browser/typing.spec.mjs
index 8b2b2a3..cbaf491 100644
--- a/tests/browser/typing.spec.mjs
+++ b/tests/browser/typing.spec.mjs
@@ -1,7 +1,12 @@
 import { test, expect } from "./fixture.mjs";
 import { open, end } from "./timeline.mjs";
 
-test.use({ productionBroker: true, readState: true, threadUnread: true });
+test.use({
+  productionBroker: true,
+  readState: true,
+  threadUnread: true,
+  historyCounts: { alpha: 20, beta: 1 },
+});
 test("Messages receives scoped typing through authenticated live traffic and expires it without publishing", async ({
   page,
   app,
diff --git a/tests/browser/unread.spec.mjs b/tests/browser/unread.spec.mjs
index 5336c90..d87f314 100644
--- a/tests/browser/unread.spec.mjs
+++ b/tests/browser/unread.spec.mjs
@@ -1,7 +1,11 @@
 import { test, expect } from "./fixture.mjs";
 import { open, settle } from "./timeline.mjs";
 
-test.use({ productionBroker: true, readState: true });
+test.use({
+  productionBroker: true,
+  readState: true,
+  historyCounts: { alpha: 640, beta: 20 },
+});
 const history = (page) =>
   page.getByRole("region", { name: "Channel message history" });
 const alpha = (page) => page.getByRole("button", { name: /^Alpha/ });