diff --git a/tests/ui/COVERAGE.md b/tests/ui/COVERAGE.md
index 32304b9b..f27e7fb6 100644
--- a/tests/ui/COVERAGE.md
+++ b/tests/ui/COVERAGE.md
@@ -92,3 +92,35 @@ in a real browser against the dev stack. Outcomes + reusable gotchas:
   with queue=collection: play links → chain hops keep the param; order
   controls appear ONLY in feed mode (player + feed page share the
   persisted override).
+
+## 2026-10-31 — round 4: user-reported control defects → knob matrix (automated)
+
+The panel sweep's blind spot, proven by the user's own two minutes:
+DOM-text snapshots show HIDDEN menus' text — "the field menu opened"
+was an illusion; the menus never VISIBLY opened, the op menu rendered
+zero items, `closeCollectionModal` removed the hidden confirm dialog
+instead of the modal, and the theme buttons died silently
+(`selectTheme(opt.Name)` — templ gotcha #1, since the CSP migration).
+
+Now automated: `knob_matrix.spec.ts` (6 specs — theme picker PUTs,
+pencil-glyph vs card body at real coordinates, builder field/op menus
+with toBeVisible + non-empty items + connective both directions, the
+Smart→Episodes create-modal seed, picker modal ladder+geometry via
+`elementFromPoint`/`boundingBox`, chain-order select persistence).
+Run: `cd tests/ui && BH_FEED=<feed uuid> npx playwright test
+--workers=1` — **`--workers=1` is load-bearing**: the login endpoint
+rate-limits and every suite shares `testuser`, so a parallel worker's
+login revokes another's mid-run (symptom: `session has expired` pages).
+
+Standing rules for every sweep from now on:
+- Menus/modals assert VISIBILITY (toBeVisible / computed display /
+  screenshot), never DOM text; every toggle click has an asserted
+  observable outcome (request fired, class flipped, value changed).
+- Geometry asserts where geometry is the bug (z-ladder via
+  `elementFromPoint`, sheet within viewport via `boundingBox`).
+- Zero new console errors per interaction; the only tolerated noise is
+  the two cancelled-transition shapes swallowed by main.ts's gate —
+  new noise gets fixed at the source, never filtered.
+- API-mutating tests seed localStorage token + selectedLibrary=__all__
+  (the mutators read the bearer from localStorage; library-scoped views
+  correctly hide episodes).
diff --git a/tests/ui/knob_matrix.spec.ts b/tests/ui/knob_matrix.spec.ts
new file mode 100644
index 00000000..39fc173e
--- /dev/null
+++ b/tests/ui/knob_matrix.spec.ts
@@ -0,0 +1,316 @@
+// The knob matrix (2026-10-31 round): every control the round touched,
+// clicked the way a user clicks, with the two assertion classes that
+// catch the whole silent-failure family:
+//   1. VISIBILITY after click — toBeVisible() on what should open.
+//      (DOM-text snapshots show hidden menus' text; only visibility
+//      catches the invisible-menu and instant-close bugs.)
+//   2. ZERO NEW console problems per interaction — the CSP build
+//      rejects bad Alpine expressions SILENTLY at the click site; an
+//      uncaught "Alpine Expression Error" is the fingerprint of every
+//      dead control this round (theme buttons, connective chip).
+// Plus geometry where geometry was the bug (modal under the sidebar,
+// modal taller than the window).
+//
+// Env-gated against the dev server: BH_BASE, BH_FEED (any feed with
+// downloaded episodes for the chain/picker checks). Fixtures are
+// created via the API and deleted at the end.
+import { test, expect, type Page } from "@playwright/test";
+
+const BASE = process.env.BH_BASE ?? "http://localhost:8765";
+const FEED = process.env.BH_FEED ?? "";
+
+test.skip(!FEED, "set BH_FEED=<feed uuid with downloaded episodes>");
+
+let consoleErrors: string[] = [];
+
+// ONE endpoint login for the whole file; rls_sweep shares this server
+// and account, and the login route rate-limits rapid attempts (a sweep
+// must not look like brute force). Tests inject the cached session
+// (cookie + localStorage) instead of logging in again.
+let sessionToken = "";
+
+async function loginEndpoint(): Promise<string> {
+  if (sessionToken) return sessionToken;
+  const res = await fetch(`${BASE}/api/auth/login`, {
+    method: "POST",
+    headers: { "Content-Type": "application/json" },
+    body: JSON.stringify({ login: "testuser", password: "Test@Pass123!" }),
+  });
+  const body = (await res.json()) as { access_token?: string };
+  if (!body.access_token) throw new Error("knob matrix login failed");
+  sessionToken = body.access_token;
+  return sessionToken;
+}
+
+async function setupSession(page: Page): Promise<void> {
+  const token = await loginEndpoint();
+  // SSR auth rides the token cookie; the theme/chain-order mutators
+  // read the bearer from localStorage (the interactive login stores it).
+  await page.addInitScript((t) => localStorage.setItem("token", t), token);
+  // Browse ALL libraries: under a single-library scope the switcher
+  // contract correctly hides episodes (the empty state is right), and
+  // the episodes fixtures here would never render.
+  await page.context().addCookies([
+    { name: "token", value: token, url: BASE },
+    { name: "selectedLibrary", value: "__all__", url: BASE },
+  ]);
+}
+
+function watchConsole(page: Page): void {
+  consoleErrors = [];
+  page.on("console", (m) => {
+    if (m.type() === "error") consoleErrors.push(m.text());
+  });
+  page.on("pageerror", (e) => consoleErrors.push(String(e)));
+}
+
+async function authedGoto(page: Page, path: string): Promise<void> {
+  await page.goto(`${BASE}${path}`);
+  if (page.url().includes("/login")) {
+    // A shared-account race (or an expired cache) — re-establish the
+    // session once and continue. The endpoint login is re-fetched fresh.
+    sessionToken = "";
+    await setupSession(page);
+    await page.goto(`${BASE}${path}`);
+  }
+}
+
+function expectNoNewConsoleErrors(): void {
+  const real = consoleErrors.filter(
+    (t) => !t.includes("Transition was skipped") && !t.includes("isFromCancelledTransition"),
+  );
+  expect(real, `console errors: ${JSON.stringify(real)}`).toEqual([]);
+}
+
+test.describe.configure({ mode: "serial" });
+
+let token = "";
+let episodesCollectionID = "";
+let staticCollectionID = "";
+
+test.beforeAll(async ({ browser }) => {
+  const page = await browser.newPage();
+  token = await loginEndpoint();
+
+  // Episodes-scope smart collection over BH_FEED (the scope door's own
+  // seed shape).
+  const res = await page.request.post(`${BASE}/api/collections`, {
+    headers: { Authorization: `Bearer ${token}` },
+    data: {
+      name: "test KnobMatrix episodes",
+      collection_type: "smart",
+      filter_tree: {
+        scope: "episodes",
+        mode: "all",
+        children: [{ field: "feed", op: "in", values: [FEED] }],
+      },
+    },
+  });
+  expect(res.status()).toBe(201);
+  episodesCollectionID = (await res.json()).id;
+
+  const stat = await page.request.post(`${BASE}/api/collections`, {
+    headers: { Authorization: `Bearer ${token}` },
+    data: { name: "test KnobMatrix static", collection_type: "static" },
+  });
+  expect(stat.status()).toBe(201);
+  staticCollectionID = (await stat.json()).id;
+  await page.close();
+});
+
+test.afterAll(async ({ browser }) => {
+  const page = await browser.newPage();
+  await loginEndpoint();
+  for (const id of [episodesCollectionID, staticCollectionID]) {
+    if (id) {
+      await page.request.delete(`${BASE}/api/collections/${id}`, {
+        headers: { Authorization: `Bearer ${token}` },
+      });
+    }
+  }
+  await page.close();
+});
+
+test("theme picker: every click persists and flips the body class", async ({ page }) => {
+  watchConsole(page);
+  await setupSession(page);
+  await authedGoto(page, "/collections");
+
+  const appearance = page.getByRole("button", { name: "Appearance" });
+  await appearance.click();
+  const dracula = page.locator('.theme-btn[data-theme="dracula"]');
+  await expect(dracula).toBeVisible();
+
+  const putTheme = page.waitForRequest(
+    (r) => r.method() === "PUT" && r.url().includes("/api/auth/theme"),
+  );
+  await dracula.click();
+  const req = await putTheme;
+  expect(req.postDataJSON()).toEqual({ theme: "dracula" });
+  await expect.poll(() => page.locator("body").getAttribute("class")).toContain("theme-dracula");
+  expectNoNewConsoleErrors();
+
+  // Back to the default (the collection list must not stay repainted).
+  // selectTheme CLOSES the panel after every pick — reopen first.
+  await appearance.click();
+  const back = page.waitForRequest(
+    (r) => r.method() === "PUT" && r.url().includes("/api/auth/theme"),
+  );
+  await page.locator('.theme-btn[data-theme="tokyo-night"]').click();
+  await back;
+  expectNoNewConsoleErrors();
+});
+
+test("pencil glyph vs card body: modal stays, card navigates", async ({ page }) => {
+  watchConsole(page);
+  await setupSession(page);
+  await authedGoto(page, "/collections");
+  const firstCard = page.locator("#collections-list > div").first();
+
+  // Click the PENCIL GLYPH (the svg inside the button) — the exact
+  // target that used to sail past the HTMLElement guard and navigate.
+  const glyph = firstCard.locator('button[aria-label="Edit collection"] svg');
+  await glyph.click();
+  await expect(page.locator("#modal-container")).toContainText("Edit Collection");
+  expect(page.url()).not.toContain("/collections/"); // still on the list
+  expectNoNewConsoleErrors();
+
+  // Card body navigates to the builder/detail page.
+  await page.locator("#modal-container button[aria-label='Close']").click();
+  // The card wrapper itself carries data-href; its center is the title
+  // area, clear of the corner buttons. (Playwright's nested locator()
+  // is descendants-only, so firstCard.locator("[data-href]") could
+  // never match — the attribute is ON the wrapper, not inside it.)
+  await firstCard.click();
+  await expect(page).toHaveURL(/\/collections\/[0-9a-f-]{36}/);
+  expectNoNewConsoleErrors();
+});
+
+test("builder: field menu, op menu (full vocabulary), connective both ways", async ({ page }) => {
+  watchConsole(page);
+  await setupSession(page);
+  await authedGoto(page, "/bookshelf");
+  await page.getByRole("button", { name: "Filters", exact: true }).click();
+
+  const fieldBtn = page.locator("button.fb-picker").first();
+  await expect(fieldBtn).toBeVisible();
+
+  // FIELD menu opens VISIBLY and a field is pickable.
+  await fieldBtn.click();
+  const fieldMenu = page.locator(".fb-menu-fields").first();
+  await expect(fieldMenu).toBeVisible();
+  await fieldMenu.locator(".fb-menu-item").first().click();
+  await expect(fieldMenu).toBeHidden();
+  expectNoNewConsoleErrors();
+
+  // OP menu opens VISIBLY with the field's operators; pick one.
+  const opBtn = page.locator("button.fb-picker-op").first();
+  await opBtn.click();
+  const opMenu = page.locator(".fb-picker-op + .fb-menu").first();
+  await expect(opMenu).toBeVisible();
+  const ops = opMenu.locator(".fb-menu-item");
+  expect(await ops.count()).toBeGreaterThan(0); // the invisible-menu bug
+  await ops.first().click();
+  await expect(opMenu).toBeHidden();
+  expectNoNewConsoleErrors();
+
+  // Second rule → the connective chip appears and toggles AND → OR → AND.
+  await page.getByRole("button", { name: "+ Rule" }).click();
+  const chip = page.locator(".fb-connective-btn:not(.fb-chip-static)").first();
+  await expect(chip).toBeVisible();
+  await expect(chip).toHaveText(/AND|OR/);
+  const before = (await chip.textContent())?.trim();
+  await chip.click();
+  const after = (await chip.textContent())?.trim();
+  expect(after).not.toBe(before); // flipped
+  await chip.click();
+  await expect(chip).toHaveText(before ?? ""); // flipped back
+  expectNoNewConsoleErrors();
+});
+
+test("create modal: Smart reveals the scope door and seeds the episodes tree", async ({ page }) => {
+  watchConsole(page);
+  await setupSession(page);
+  await authedGoto(page, "/collections");
+  await page.getByRole("button", { name: "New Collection" }).click();
+
+  // The radios are sr-only (visually hidden); a human clicks the LABEL.
+  await page.locator('#modal-container label:has(input[value="smart"])').click();
+  const scopeRow = page.locator("#modal-container #collection-tree-seed");
+  await expect(scopeRow).toBeAttached();
+
+  await page.getByRole("button", { name: "🎧 Podcast episodes" }).click();
+  const hidden = page.locator("#collection-tree-seed");
+  const seed = await hidden.inputValue();
+  const parsed = JSON.parse(seed);
+  expect(parsed).toEqual({ scope: "episodes", mode: "all", children: [] });
+
+  // Books scope clears the seed (tree-less = the books default).
+  await page.getByRole("button", { name: "📚 Books" }).click();
+  expect(await hidden.inputValue()).toBe("");
+  expectNoNewConsoleErrors();
+});
+
+test("episodes picker modal: above the sidebar, inside the viewport", async ({ page }) => {
+  watchConsole(page);
+  await setupSession(page);
+  await page.setViewportSize({ width: 1280, height: 720 });
+  await authedGoto(page, `/collections/${staticCollectionID}`);
+
+  await page.getByRole("button", { name: "Add Items" }).click();
+  const overlay = page.locator('div[x-data="bookPicker"]');
+  await expect(overlay).toBeVisible();
+
+  // LADDER: the point over the SIDEBAR must hit the OVERLAY, not the
+  // nav (the z-50-under-z-60 bug put the modal's left edge beneath it).
+  const sidebar = page.locator(".app-sidebar");
+  const sb = await sidebar.boundingBox();
+  const ov = await overlay.boundingBox();
+  expect(sb).not.toBeNull();
+  expect(ov).not.toBeNull();
+  const hit = await page.evaluate(
+    ([x, y]) => {
+      const el = document.elementFromPoint(x as number, y as number);
+      return el ? el.closest('div[x-data="bookPicker"]') !== null : false;
+    },
+    [sb!.x + 20, sb!.y + 300] as [number, number],
+  );
+  expect(hit, "the sidebar point must land on the picker overlay").toBe(true);
+
+  // GEOMETRY: the dialog card fits the viewport (footer reachable).
+  const card = overlay.locator(".card").first();
+  const cb = await card.boundingBox();
+  expect(cb).not.toBeNull();
+  expect(cb!.y + cb!.height).toBeLessThanOrEqual(720 + 1);
+  expectNoNewConsoleErrors();
+
+  // Scope tabs: Episodes tab loads rows (downloaded badge present).
+  await overlay.getByRole("button", { name: /Episodes/ }).click();
+  const epGrid = page.locator("#episode-picker-grid");
+  await expect(epGrid).toBeVisible();
+  await expect(epGrid.locator(".fb-menu-empty, div").first()).toBeVisible();
+  await page.keyboard.press("Escape");
+  await expect(overlay).toBeHidden();
+  expectNoNewConsoleErrors();
+});
+
+test("chain order select: flip persists and the chain honors it", async ({ page }) => {
+  watchConsole(page);
+  await setupSession(page);
+  await authedGoto(page, `/collections/${episodesCollectionID}`);
+
+  const select = page.locator("#chain-order-select");
+  await expect(select).toBeVisible(); // only renders with playable episodes
+
+  const putOrder = page.waitForRequest(
+    (r) => r.method() === "PUT" && r.url().includes("/view-settings"),
+  );
+  await select.selectOption("newest");
+  const req = await putOrder;
+  expect(req.postDataJSON()).toEqual({ chain_order: "newest" });
+
+  // The page reloads; the stored order renders as selected.
+  await page.waitForLoadState("load");
+  await expect(select).toHaveValue("newest");
+  expectNoNewConsoleErrors();
+});