chore(coach): lift the rail-tray chevrons out of the overlay

The mobile history + sources tray triggers used to mount as absolute
chevron buttons over the message thread, so they (a) overlapped the
first message bubble, (b) sat at a 28 px tap target (`h-7`), and (c)
relied on `backdrop-blur` to stay legible — which still failed on
busy threads.

Lift them into a sub-header strip above the thread: a flex row with
two ghost buttons at `min-h-11`. The strip itself carries `xl:hidden`
since both rails are inline at xl+; the history trigger keeps its own
`lg:hidden` because the history rail mounts inline already at lg+.

While the rail surface is in scope, drop the `opacity-0
group-hover:opacity-100` reveal on the history-rail per-row delete
button — touch surfaces have no hover, so the affordance was
invisible on mobile. The button now sits at `size-11` always-visible;
the confirming state still styles via `data-confirming`.

Test re-baselined to assert the new strip wrapper + `min-h-11` floor.

src/components/insights/coach-panel/__tests__/coach-drawer-mobile-trays.test.tsx

@@ -41,18 +41,22 @@ describe("<CoachDrawerBody> — mobile rail trays", () => {
   });
 
   it("hides the history trigger on >=lg and the sources trigger on >=xl", () => {
+    // v1.4.27 R3d MB2 — the strip wrapper carries `xl:hidden` so the
+    // sources trigger inherits the breakpoint; the history trigger
+    // keeps its own `lg:hidden` because the history rail mounts
+    // inline already on lg+ while the sources rail still needs the
+    // chevron until xl.
     const html = render(<CoachDrawerBody {...baseProps} />);
+    const strip = html.match(
+      /<div[^>]*data-slot="coach-drawer-rail-tray-strip"[^>]*>/,
+    );
+    expect(strip?.[0]).toContain("xl:hidden");
+
     const historyTrigger = html.match(
       /<button[^>]*data-slot="coach-drawer-history-tray-trigger"[^>]*>/,
     );
     expect(historyTrigger).not.toBeNull();
     expect(historyTrigger?.[0]).toContain("lg:hidden");
-
-    const sourcesTrigger = html.match(
-      /<button[^>]*data-slot="coach-drawer-sources-tray-trigger"[^>]*>/,
-    );
-    expect(sourcesTrigger).not.toBeNull();
-    expect(sourcesTrigger?.[0]).toContain("xl:hidden");
   });
 
   it("renders the desktop history rail (lg+) and sources rail (xl+)", () => {
@@ -95,12 +99,16 @@ describe("<CoachDrawerBody> — mobile rail trays", () => {
     expect(html).toContain("Worauf ich zugreife");
   });
 
-  it("the thread region wraps the rail triggers in a relative container", () => {
-    // The triggers use absolute positioning; the thread region must
-    // be `relative` for them to anchor inside it.
+  it("renders the rail triggers in a sub-header strip above the thread", () => {
+    // v1.4.27 R3d MB2 — the triggers were lifted out of the absolute
+    // overlay into a sub-header strip so the chevrons sit at a 44 px
+    // tap target and never overlay the first message bubble. The
+    // strip lives above the thread within the centre column.
     const html = render(<CoachDrawerBody {...baseProps} />);
-    expect(html).toMatch(
-      /<main[^>]*data-slot="coach-drawer-thread"[^>]*relative/,
+    expect(html).toMatch(/data-slot="coach-drawer-rail-tray-strip"/);
+    const trigger = html.match(
+      /<button[^>]*data-slot="coach-drawer-history-tray-trigger"[^>]*>/,
     );
+    expect(trigger?.[0]).toContain("min-h-11");
   });
 });

src/components/insights/coach-panel/coach-drawer-body.tsx

@@ -59,36 +59,48 @@ export function CoachDrawerBody({
       {/* Centre — message thread. */}
       <main
         data-slot="coach-drawer-thread"
-        className="relative flex h-full min-h-0 flex-col"
+        className="flex h-full min-h-0 flex-col"
       >
-        {/* v1.4.20 phase B4 — mobile rail tray triggers. Hidden on
-            `>=lg` because the rails are inline there. */}
-        <Button
-          type="button"
-          variant="ghost"
-          size="sm"
-          onClick={onOpenHistoryTray}
-          data-slot="coach-drawer-history-tray-trigger"
-          aria-label={t("insights.coach.historyTitle")}
-          className="bg-background/80 border-border/60 absolute top-2 left-2 z-10 h-7 gap-1 border px-2 text-[11px] backdrop-blur lg:hidden"
+        {/* v1.4.27 R3d MB2 — rail-tray triggers lifted out of the
+            absolute overlay into a sub-header strip so the chevrons
+            sit at a 44 px tap target and never overlay the first
+            message bubble. Hidden on `>=xl` because both rails are
+            inline at that breakpoint. The history trigger remains
+            visible up to lg-1 (rail is inline at lg+); the sources
+            trigger remains visible up to xl-1 (rail is inline at
+            xl+). */}
+        <div
+          data-slot="coach-drawer-rail-tray-strip"
+          className="border-border/70 flex items-center justify-between gap-2 border-b px-3 py-2 xl:hidden"
         >
-          <ChevronRight className="size-3" aria-hidden="true" />
-          {t("insights.coach.historyTitle")}
-        </Button>
-        {/* Sources tray trigger stays visible up to xl since the
-            inline sources rail is xl+ only. */}
-        <Button
-          type="button"
-          variant="ghost"
-          size="sm"
-          onClick={onOpenSourcesTray}
-          data-slot="coach-drawer-sources-tray-trigger"
-          aria-label={t("insights.coach.sourcesTitle")}
-          className="bg-background/80 border-border/60 absolute top-2 right-2 z-10 h-7 gap-1 border px-2 text-[11px] backdrop-blur xl:hidden"
-        >
-          {t("insights.coach.sourcesTitle")}
-          <ChevronLeft className="size-3" aria-hidden="true" />
-        </Button>
+          <Button
+            type="button"
+            variant="ghost"
+            onClick={onOpenHistoryTray}
+            data-slot="coach-drawer-history-tray-trigger"
+            aria-label={t("insights.coach.historyTitle")}
+            className="min-h-11 gap-1.5 text-xs lg:hidden"
+          >
+            <ChevronRight className="size-4" aria-hidden="true" />
+            {t("insights.coach.historyTitle")}
+          </Button>
+          {/* Sources tray trigger stays visible up to xl since the
+              inline sources rail is xl+ only. The empty `<span>` to
+              the left keeps the right-aligned button placement when
+              the history trigger hides at lg+. */}
+          <span aria-hidden="true" className="hidden lg:block" />
+          <Button
+            type="button"
+            variant="ghost"
+            onClick={onOpenSourcesTray}
+            data-slot="coach-drawer-sources-tray-trigger"
+            aria-label={t("insights.coach.sourcesTitle")}
+            className="min-h-11 gap-1.5 text-xs"
+          >
+            {t("insights.coach.sourcesTitle")}
+            <ChevronLeft className="size-4" aria-hidden="true" />
+          </Button>
+        </div>
 
         <div className="min-h-0 flex-1">{thread}</div>
         {/* Composer pinned to the bottom. */}

src/components/insights/coach-panel/history-rail.tsx

@@ -138,6 +138,12 @@ export function HistoryRail({
                     {formatRelativeTime(c.updatedAt, t)}
                   </span>
                 </button>
+                {/* v1.4.27 R3d MB2 — drop the hover-only `opacity-0`
+                    reveal: touch surfaces have no hover, so the delete
+                    affordance was invisible on mobile. The button now
+                    sits at 44 px always-visible per the WCAG 2.5.5
+                    floor; confirming state stays styled via the
+                    `data-confirming` attribute. */}
                 <Button
                   type="button"
                   variant="ghost"
@@ -151,12 +157,12 @@ export function HistoryRail({
                   data-slot="coach-history-delete"
                   data-confirming={isConfirming ? "true" : undefined}
                   className={cn(
-                    "size-6 shrink-0 opacity-0 transition-opacity group-hover:opacity-100",
+                    "size-11 shrink-0",
                     isConfirming &&
-                      "text-dracula-red hover:text-dracula-red opacity-100",
+                      "text-dracula-red hover:text-dracula-red",
                   )}
                 >
-                  <Trash2 className="size-3.5" aria-hidden="true" />
+                  <Trash2 className="size-4" aria-hidden="true" />
                 </Button>
               </div>
             );