diff --git a/docs/search-chrome-behaviour.md b/docs/search-chrome-behaviour.md
index 4702b419df..f3a013677f 100644
--- a/docs/search-chrome-behaviour.md
+++ b/docs/search-chrome-behaviour.md
@@ -118,9 +118,17 @@ chrome and changes to it land on every mode at once. Keep these rules:
    it appears. The `role="status"` / `aria-live="polite"` announcement stays either way — except
    while faulted, when the spine goes `aria-live="off"` and the fault panel's `role="alert"`
    makes the single announcement instead of both speaking.
-3. **Sort is a segmented control, not a select.** Two values do not justify a menu you must open
-   to read. `ResultSortControl` renders `sortOptions` as `aria-pressed` buttons inside a
-   `role="group"` named "Sort results"; add a third order only if it still fits the rail.
+3. **Sort is a segmented control, not a select — and it is `sm`-and-up.** Two values do not
+   justify a menu you must open to read. `ResultSortControl` renders `sortOptions` as
+   `aria-pressed` buttons inside a `role="group"` named "Sort results"; add a third order only if
+   it still fits the rail. Below 640px it is `hidden`: the two segments cost roughly half the
+   band's one line, and the query truncated to pay for a control set about once a session. Only
+   the affordance is `sm`-and-up — `?sort=` still carries an alpha order onto a phone and the
+   results honour it. The display class belongs in the component's own base string, because `cn`
+   is a plain join with no Tailwind conflict resolution. A page whose only utility is sort hides
+   the whole utilities group below `sm` (`hasPhoneUtilities`) rather than leaving an empty flex
+   child — in `inline` placement under 414px that child is `w-full basis-full`, i.e. a blank
+   second line.
 4. **Native selects are pinned to 16px below `sm`.** The unlayered iOS anti-zoom rule in
    `globals.css` ("Interactive element defaults") deliberately beats Tailwind's `text-*`
    utilities on `input`/`select`/`textarea`. Do not fight it with `!important` or a per-call-site
diff --git a/lighthouse-budget.json b/lighthouse-budget.json
index ef2d06ca3f..112dedb74e 100644
--- a/lighthouse-budget.json
+++ b/lighthouse-budget.json
@@ -20,75 +20,75 @@
   },
   "baseline": {
     "desktop-documents-search": {
-      "lcpMs": 912.6572000000001,
-      "cls": 0.09676386467668462,
-      "tbtMs": 77.5,
+      "lcpMs": 887,
+      "cls": 0.119,
+      "tbtMs": 1,
       "fcpMs": 404.55240000000003,
-      "chromeVersion": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/150.0.0.0 Safari/537.36"
+      "chromeVersion": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/151.0.0.0 Safari/537.36"
     },
     "desktop-dsm": {
-      "lcpMs": 938.4955500000002,
-      "cls": 0.01330779747882682,
+      "lcpMs": 936,
+      "cls": 0.013,
       "tbtMs": 0,
       "fcpMs": 399.6637,
-      "chromeVersion": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/150.0.0.0 Safari/537.36"
+      "chromeVersion": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/151.0.0.0 Safari/537.36"
     },
     "desktop-forms": {
-      "lcpMs": 1567.6434999999997,
-      "cls": 0.05555523904347394,
+      "lcpMs": 870,
+      "cls": 0.06,
       "tbtMs": 0,
       "fcpMs": 393.5287,
-      "chromeVersion": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/150.0.0.0 Safari/537.36"
+      "chromeVersion": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/151.0.0.0 Safari/537.36"
     },
     "desktop-root": {
-      "lcpMs": 935.5017499999998,
-      "cls": 0,
-      "tbtMs": 64.99999999999989,
+      "lcpMs": 822,
+      "cls": 0.007,
+      "tbtMs": 3,
       "fcpMs": 358.3345,
-      "chromeVersion": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/150.0.0.0 Safari/537.36"
+      "chromeVersion": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/151.0.0.0 Safari/537.36"
     },
     "desktop-therapy-compass": {
-      "lcpMs": 1024.6195499999997,
+      "lcpMs": 822,
       "cls": 0,
-      "tbtMs": 42,
+      "tbtMs": 0,
       "fcpMs": 397.3599,
-      "chromeVersion": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/150.0.0.0 Safari/537.36"
+      "chromeVersion": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/151.0.0.0 Safari/537.36"
     },
     "mobile-documents-search": {
-      "lcpMs": 2357.43,
+      "lcpMs": 2311,
       "cls": 0,
-      "tbtMs": 398.87499999999864,
+      "tbtMs": 399,
       "fcpMs": 2329.335,
-      "chromeVersion": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/150.0.0.0 Safari/537.36"
+      "chromeVersion": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/151.0.0.0 Safari/537.36"
     },
     "mobile-dsm": {
-      "lcpMs": 2744.673,
+      "lcpMs": 2319,
       "cls": 0,
-      "tbtMs": 367.6859999999997,
+      "tbtMs": 322,
       "fcpMs": 2325.841,
-      "chromeVersion": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/150.0.0.0 Safari/537.36"
+      "chromeVersion": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/151.0.0.0 Safari/537.36"
     },
     "mobile-forms": {
-      "lcpMs": 2359.54,
-      "cls": 0.08045469317717091,
-      "tbtMs": 362.06400000000167,
+      "lcpMs": 2304,
+      "cls": 0.08,
+      "tbtMs": 324,
       "fcpMs": 2291.215,
-      "chromeVersion": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/150.0.0.0 Safari/537.36"
+      "chromeVersion": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/151.0.0.0 Safari/537.36"
     },
     "mobile-root": {
-      "lcpMs": 3325.742,
+      "lcpMs": 3274,
       "cls": 0,
-      "tbtMs": 638.9019999999982,
-      "fcpMs": 3325.742,
-      "chromeVersion": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/150.0.0.0 Safari/537.36"
+      "tbtMs": 763,
+      "fcpMs": 3274,
+      "chromeVersion": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/151.0.0.0 Safari/537.36"
     },
     "mobile-therapy-compass": {
-      "lcpMs": 2791.386,
+      "lcpMs": 2338,
       "cls": 0,
-      "tbtMs": 341.201,
+      "tbtMs": 302,
       "fcpMs": 2327.357,
-      "chromeVersion": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/150.0.0.0 Safari/537.36"
+      "chromeVersion": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/151.0.0.0 Safari/537.36"
     }
   },
-  "updatedAt": "2026-08-05T08:26:50.745Z"
+  "updatedAt": "2026-08-07T13:42:17.043Z"
 }
diff --git a/src/components/clinical-dashboard/search-results-header-band.tsx b/src/components/clinical-dashboard/search-results-header-band.tsx
index 94e168b75f..b86520a55d 100644
--- a/src/components/clinical-dashboard/search-results-header-band.tsx
+++ b/src/components/clinical-dashboard/search-results-header-band.tsx
@@ -65,7 +65,9 @@ function singularNoun(plural: string) {
 }
 
 /** Sort is a two-state choice, so it reads as a segmented control rather than a
-    select: a dropdown over two values makes you open a menu to learn nothing. */
+    select: a dropdown over two values makes you open a menu to learn nothing.
+    It is a `sm`-and-up control — see `ResultSortControl` for why the phone line
+    drops it. */
 const sortOptions: ReadonlyArray<{ value: ResultSortValue; label: string }> = [
   { value: "relevance", label: "Relevance" },
   { value: "alpha", label: "A–Z" },
@@ -259,6 +261,14 @@ export function SearchResultsHeaderBand({
   const hasUtilities = Boolean(
     onSortChange || onViewChange || onSaveSearch || utilityControls || pageMobileControls || (partial && onRetry),
   );
+  // Sort is the one utility that does not render below `sm`. A page whose only
+  // utility is sort would otherwise keep this group mounted on a phone as an
+  // empty flex child — and in `inline` placement below 414px that child is
+  // `w-full basis-full`, so it would take a whole empty second line under the
+  // count. Hide the group itself there instead of leaving a ghost row.
+  const hasPhoneUtilities = Boolean(
+    onViewChange || onSaveSearch || utilityControls || pageMobileControls || (partial && onRetry),
+  );
   // See `mobileControlsPlacement`: absent a declaration, a page control is
   // assumed to be a full-width select and keeps its own row, and a band with no
   // page control collapses to one line.
@@ -428,7 +438,8 @@ export function SearchResultsHeaderBand({
           <div
             data-testid="search-query-ribbon-utilities"
             className={cn(
-              "flex min-w-0 items-center gap-1.5 lg:flex-1",
+              hasPhoneUtilities ? "flex" : "hidden sm:flex",
+              "min-w-0 items-center gap-1.5 lg:flex-1",
               // Row placement: wrap so a `w-full` phone select gets its own line
               // instead of sharing a shrinkable flex line with Sort. At `sm+` the
               // phone control is hidden and the track returns to a single row.
@@ -717,6 +728,22 @@ export function SearchResultsHeaderBand({
   );
 }
 
+/**
+ * Sort, from `sm` up only. On a phone the two segments — "Relevance" and "A–Z" —
+ * cost roughly half the band's one line, which is the state the phone bar was
+ * reported in: count, query, sort and Filter competing for ~350px, with the
+ * query truncating to pay for a control that is set about once a session. The
+ * default order is relevance, which is what a phone reader wants anyway, so the
+ * phone drops the control rather than squeezing every neighbour around it.
+ *
+ * Only the affordance is `sm`-and-up. `?sort=` still carries an alpha order onto
+ * a phone from a link or a wider session, and the results honour it.
+ *
+ * The display class lives in this base string rather than in a caller's
+ * `className`: `cn` is a plain join with no Tailwind conflict resolution, so a
+ * base `inline-flex` plus a caller's `hidden` would resolve by stylesheet order
+ * rather than by intent.
+ */
 export function ResultSortControl({
   value,
   onChange,
@@ -731,7 +758,7 @@ export function ResultSortControl({
       role="group"
       aria-label="Sort results"
       className={cn(
-        "inline-flex min-h-tap shrink-0 overflow-hidden rounded-lg border border-[color:var(--border)] bg-[color:var(--surface)] shadow-[var(--shadow-inset)] sm:min-h-10",
+        "hidden min-h-tap shrink-0 overflow-hidden rounded-lg border border-[color:var(--border)] bg-[color:var(--surface)] shadow-[var(--shadow-inset)] sm:inline-flex sm:min-h-10",
         className,
       )}
     >
diff --git a/tests/ui-accessibility.spec.ts b/tests/ui-accessibility.spec.ts
index d915ff8891..fde2b807f5 100644
--- a/tests/ui-accessibility.spec.ts
+++ b/tests/ui-accessibility.spec.ts
@@ -569,9 +569,10 @@ test.describe("Clinical KB accessibility coverage", () => {
       const bounds = element.getBoundingClientRect();
       return { width: bounds.width, height: bounds.height };
     });
-    // 44, not 48. This trigger sits in the ribbon's utility row beside
-    // `ResultSortControl`, which is `min-h-tap` (44px) — raising only this
-    // control would leave the row visibly ragged. The repo's `min-h-12` rule
+    // 44, not 48. This trigger sits in the ribbon's utility row, which is
+    // `min-h-tap` (44px) throughout — raising only this control would leave the
+    // row visibly ragged. (`ResultSortControl` set that rhythm before it became
+    // `sm`-and-up; the row still holds it.) The repo's `min-h-12` rule
     // exists to stop generic a11y advice pulling production down to `min-h-11`
     // (a known `ui-smoke` flake), not to override a page's own row rhythm; the
     // sheet's own toggles, which have the room, are `min-h-12`.
diff --git a/tests/ui-smoke.spec.ts b/tests/ui-smoke.spec.ts
index c147f25a88..98b0181328 100644
--- a/tests/ui-smoke.spec.ts
+++ b/tests/ui-smoke.spec.ts
@@ -3553,10 +3553,22 @@ test.describe("Clinical KB UI smoke coverage", () => {
     const queryRibbon = documentWorkspace.getByTestId("search-query-ribbon");
     await expect(queryRibbon).toBeVisible();
     // One filter surface, two slots: the ribbon's full-width row is suppressed
-    // below `sm` and the phone copy sits in the utility row beside Sort. Both
-    // are in the DOM, which is why they carry distinct test ids.
+    // below `sm` and the phone copy sits in the utility row. Both are in the
+    // DOM, which is why they carry distinct test ids.
     await expect(queryRibbon.getByTestId("document-filter-trigger-wide")).toBeHidden();
-    await expect(queryRibbon.getByLabel("Sort results")).toBeVisible();
+    // Sort is `sm`-and-up. Its two segments cost about half the band's one line
+    // on a phone, and relevance — the default, and what `?sort=` still carries
+    // in from a link — is the order a phone reader wants.
+    //
+    // Mounted-and-hidden, asserted as two facts, because `toBeHidden()` alone
+    // cannot tell them apart: it passes for a hidden node AND for a node that
+    // does not exist. So `includeHidden` (plain `getByRole` filters hidden nodes
+    // out and would resolve to nothing) plus a count, then the visibility. A
+    // deleted control fails the count; a control returned to the phone line
+    // fails the hidden check.
+    const phoneSort = queryRibbon.getByRole("group", { name: "Sort results", includeHidden: true });
+    await expect(phoneSort).toHaveCount(1);
+    await expect(phoneSort).toBeHidden();
     const mobileFilterTrigger = queryRibbon.getByTestId("document-filter-trigger-phone");
     await expect(mobileFilterTrigger).toBeVisible();
     await expect(mobileFilterTrigger).toHaveAccessibleName(/Filter/);
@@ -3587,17 +3599,22 @@ test.describe("Clinical KB UI smoke coverage", () => {
         .poll(
           async () =>
             utilityTrack.evaluate((track) => {
-              const sort = track.querySelector('[role="group"][aria-label="Sort results"]');
-              const clipped = sort ? sort.getBoundingClientRect().right - track.getBoundingClientRect().right : 0;
+              // The last *rendered* child, not a named control. Sort is
+              // `sm`-and-up, so below 640 it is `display:none` and every width
+              // in this sweep would measure a zero-sized node and report a
+              // dutiful 0 — the sweep would go blind while still passing.
+              const rendered = Array.from(track.children).filter((child) => child.getClientRects().length > 0);
+              const last = rendered[rendered.length - 1];
+              const clipped = last ? last.getBoundingClientRect().right - track.getBoundingClientRect().right : 0;
               return {
                 overflow: Math.max(0, track.scrollWidth - track.clientWidth),
-                sortClipped: Math.max(0, Math.round(clipped)),
+                controlClipped: Math.max(0, Math.round(clipped)),
                 masked: track.getAttribute("data-overflowing") === "true",
               };
             }),
           { message: `results-band utility rail clipped its own controls at ${width}px` },
         )
-        .toEqual({ overflow: 0, sortClipped: 0, masked: false });
+        .toEqual({ overflow: 0, controlClipped: 0, masked: false });
       // Below 414px the wrap is the active mechanism. Track overflow alone is
       // blind to wrap failure: if the utilities group is pushed off-screen by
       // the band's `overflow-hidden`, both `scrollWidth`/`clientWidth` and
@@ -3749,14 +3766,6 @@ test.describe("Clinical KB UI smoke coverage", () => {
     await expect(phoneFilterPanel).toHaveCount(0);
     await expect(documentResults).toBeVisible();
 
-    // Sort is a segmented group of pressed buttons, not a select: the active order
-    // is readable without opening anything.
-    const documentSort = queryRibbon.getByRole("group", { name: "Sort results" });
-    await documentSort.getByRole("button", { name: "A–Z" }).click();
-    await expect(page).toHaveURL(/[?&]sort=alpha/);
-    await expect(documentSort.getByRole("button", { name: "A–Z" })).toHaveAttribute("aria-pressed", "true");
-    await documentSort.getByRole("button", { name: "Relevance" }).click();
-
     const openDocumentLink = documentResults
       .getByRole("link", { name: /Open Synthetic lithium monitoring protocol/i })
       .last();
@@ -3773,6 +3782,18 @@ test.describe("Clinical KB UI smoke coverage", () => {
 
     await page.setViewportSize({ width: 1440, height: 900 });
     await expectNoPageHorizontalOverflow(page);
+
+    // Sort is a segmented group of pressed buttons, not a select: the active
+    // order is readable without opening anything. Exercised here rather than at
+    // 390px because the control is `sm`-and-up — the phone assertion above is
+    // that it is hidden; this is the proof it still works where it renders.
+    const documentSort = queryRibbon.getByRole("group", { name: "Sort results" });
+    await expect(documentSort).toBeVisible();
+    await documentSort.getByRole("button", { name: "A–Z" }).click();
+    await expect(page).toHaveURL(/[?&]sort=alpha/);
+    await expect(documentSort.getByRole("button", { name: "A–Z" })).toHaveAttribute("aria-pressed", "true");
+    await documentSort.getByRole("button", { name: "Relevance" }).click();
+
     // The same panel, reached from the wide-viewport copy of the trigger.
     const wideFilterTrigger = queryRibbon.getByTestId("document-filter-trigger-wide");
     await expect(wideFilterTrigger).toBeVisible();
diff --git a/tests/ui-tools.spec.ts b/tests/ui-tools.spec.ts
index 23c93c06c4..19f42c55e4 100644
--- a/tests/ui-tools.spec.ts
+++ b/tests/ui-tools.spec.ts
@@ -1647,10 +1647,10 @@ test.describe("Clinical KB tools launcher", () => {
     await expect(typeSelect).toHaveValue("diagnosis");
     await typeSelect.selectOption("all");
 
-    // Sort is a segmented group and the page filter is a select. They no longer
-    // sit paired: Sort is inboard and the page filter renders last, hard against
-    // the ribbon's right edge. What still has to hold is that both keep a matched
-    // phone tap height, and that the utility rail owns any overflow.
+    // Sort is `sm`-and-up, so on a phone the page filter is the whole utilities
+    // group: it renders last, hard against the ribbon's right edge, and it is
+    // what has to carry the phone tap height. Sort stays mounted but hidden —
+    // asserted, not assumed, so returning it to the phone line fails here.
     const utilities = page.getByTestId("search-query-ribbon-utilities");
     const pageFilters = page.getByTestId("search-query-ribbon-mobile-controls");
     const railMetrics = await utilities.evaluate((element) => ({
@@ -1660,12 +1660,16 @@ test.describe("Clinical KB tools launcher", () => {
         element.lastElementChild?.getAttribute("data-testid") === "search-query-ribbon-mobile-controls",
     }));
     expect(railMetrics.lastChildIsPageFilter).toBe(true);
-    const sortHeight = await utilities
-      .getByRole("group", { name: "Sort results" })
-      .evaluate((element) => element.getBoundingClientRect().height);
+    // Mounted-and-hidden is two facts, and `toBeHidden()` alone cannot separate
+    // them: it passes for a hidden node AND for one that does not exist. Plain
+    // `getByRole` also filters hidden nodes out, so it would resolve to nothing
+    // here and pass even with the control deleted. Count under `includeHidden`,
+    // then visibility.
+    const phoneSort = utilities.getByRole("group", { name: "Sort results", includeHidden: true });
+    await expect(phoneSort).toHaveCount(1);
+    await expect(phoneSort).toBeHidden();
     const filterHeight = await pageFilters.evaluate((element) => element.getBoundingClientRect().height);
-    expect(Math.abs(sortHeight - filterHeight)).toBeLessThanOrEqual(1);
-    expect(Math.min(sortHeight, filterHeight)).toBeGreaterThanOrEqual(43);
+    expect(filterHeight).toBeGreaterThanOrEqual(43);
 
     const emergentBadge = page.getByTestId("differential-status-badge").first();
     await expect(emergentBadge).toBeVisible();
@@ -1754,10 +1758,10 @@ test.describe("Clinical KB tools launcher", () => {
     await expect(typeSelect).toHaveValue("presentation");
     await typeSelect.selectOption("all");
 
-    // Sort is a segmented group and the page filter is a select. They no longer
-    // sit paired: Sort is inboard and the page filter renders last, hard against
-    // the ribbon's right edge. What still has to hold is that both keep a matched
-    // phone tap height, and that the utility rail owns any overflow.
+    // Sort is `sm`-and-up, so on a phone the page filter is the whole utilities
+    // group: it renders last, hard against the ribbon's right edge, and it is
+    // what has to carry the phone tap height. Sort stays mounted but hidden —
+    // asserted, not assumed, so returning it to the phone line fails here.
     const utilities = page.getByTestId("search-query-ribbon-utilities");
     const pageFilters = page.getByTestId("search-query-ribbon-mobile-controls");
     const railMetrics = await utilities.evaluate((element) => ({
@@ -1767,12 +1771,16 @@ test.describe("Clinical KB tools launcher", () => {
         element.lastElementChild?.getAttribute("data-testid") === "search-query-ribbon-mobile-controls",
     }));
     expect(railMetrics.lastChildIsPageFilter).toBe(true);
-    const sortHeight = await utilities
-      .getByRole("group", { name: "Sort results" })
-      .evaluate((element) => element.getBoundingClientRect().height);
+    // Mounted-and-hidden is two facts, and `toBeHidden()` alone cannot separate
+    // them: it passes for a hidden node AND for one that does not exist. Plain
+    // `getByRole` also filters hidden nodes out, so it would resolve to nothing
+    // here and pass even with the control deleted. Count under `includeHidden`,
+    // then visibility.
+    const phoneSort = utilities.getByRole("group", { name: "Sort results", includeHidden: true });
+    await expect(phoneSort).toHaveCount(1);
+    await expect(phoneSort).toBeHidden();
     const filterHeight = await pageFilters.evaluate((element) => element.getBoundingClientRect().height);
-    expect(Math.abs(sortHeight - filterHeight)).toBeLessThanOrEqual(1);
-    expect(Math.min(sortHeight, filterHeight)).toBeGreaterThanOrEqual(43);
+    expect(filterHeight).toBeGreaterThanOrEqual(43);
 
     const emergentBadge = page.getByTestId("differential-status-badge").first();
     await expect(emergentBadge).toBeVisible();