fix(coach): cap drawer width on lg+ and route sources rail via tray

The drawer's lg:max-w-[1080px] cap left only ~200-286px of underlying
/insights visible on common laptop viewports (1280-1366px), turning
the "keep dashboard context behind it" sheet into a near-takeover.

Drop the lg cap to min(960px,75vw) with the inline sources rail
hidden below xl — the rail still surfaces on lg via the existing
mobile chevron tab. xl+ restores the full three-column layout. The
history rail stays visible inline on lg+ (it's the more frequently
referenced of the two).

Update the SSR test contract to match: history trigger hides on lg+,
sources trigger hides on xl+.

Fixes Design-HIGH-1.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

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

@@ -9,10 +9,13 @@ import { CoachDrawerBody } from "../coach-drawer-body";
  *
  * The drawer hides the history + sources rails on `<lg`. B4 adds two
  * chevron-button triggers along the edges of the message thread that
- * open side-sheets surfacing the same rails. The triggers live on
+ * open side-sheets surfacing the same rails.
- * `<CoachDrawerBody>` so the SSR test can pin their `lg:hidden` class
+ *
- * + slot markers without rendering the outer Radix `<Sheet>` portal
+ * Phase D reconcile narrowed the lg drawer cap (was 1080px → now
- * (which is client-only).
+ * min(960px,75vw)) so the inline sources rail no longer fits below
+ * xl. The history rail surfaces inline on lg; the sources rail
+ * surfaces inline on xl. Mobile chevron triggers cover the missing
+ * rails: history hidden on lg+, sources hidden on xl+.
  */
 
 function render(node: React.ReactNode, locale: "en" | "de" = "en") {
@@ -37,7 +40,7 @@ describe("<CoachDrawerBody> — mobile rail trays", () => {
     expect(html).toMatch(/data-slot="coach-drawer-sources-tray-trigger"/);
   });
 
-  it("hides both triggers on >=lg via the lg:hidden class", () => {
+  it("hides the history trigger on >=lg and the sources trigger on >=xl", () => {
     const html = render(<CoachDrawerBody {...baseProps} />);
     const historyTrigger = html.match(
       /<button[^>]*data-slot="coach-drawer-history-tray-trigger"[^>]*>/,
@@ -49,16 +52,16 @@ describe("<CoachDrawerBody> — mobile rail trays", () => {
       /<button[^>]*data-slot="coach-drawer-sources-tray-trigger"[^>]*>/,
     );
     expect(sourcesTrigger).not.toBeNull();
-    expect(sourcesTrigger?.[0]).toContain("lg:hidden");
+    expect(sourcesTrigger?.[0]).toContain("xl:hidden");
   });
 
-  it("renders the desktop history + sources rails (visible on >=lg)", () => {
+  it("renders the desktop history rail (lg+) and sources rail (xl+)", () => {
     const html = render(<CoachDrawerBody {...baseProps} />);
     expect(html).toMatch(
       /<aside[^>]*data-slot="coach-drawer-history"[^>]*lg:flex/,
     );
     expect(html).toMatch(
-      /<aside[^>]*data-slot="coach-drawer-sources"[^>]*lg:flex/,
+      /<aside[^>]*data-slot="coach-drawer-sources"[^>]*xl:flex/,
     );
   });
 

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

@@ -41,7 +41,11 @@ export function CoachDrawerBody({
   return (
     <div
       data-slot="coach-drawer-body"
-      className="grid min-h-0 flex-1 grid-cols-1 lg:grid-cols-[260px_1fr_280px]"
+      // v1.4.20 phase D reconcile — narrower drawer cap at lg means the
+      // sources rail no longer fits inline below xl. lg gets the
+      // history rail + thread (sources surface via the chevron tray);
+      // xl+ restores the full three-column layout.
+      className="grid min-h-0 flex-1 grid-cols-1 lg:grid-cols-[260px_1fr] xl:grid-cols-[260px_1fr_280px]"
     >
       {/* History rail — desktop only. Mobile users summon it via the
           tray trigger inside the thread column. */}
@@ -71,6 +75,8 @@ export function CoachDrawerBody({
           <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"
@@ -78,7 +84,7 @@ export function CoachDrawerBody({
           onClick={onOpenSourcesTray}
           data-slot="coach-drawer-sources-tray-trigger"
           aria-label={t("insights.coach.sourcesTitle")}
-          className="bg-background/80 border-border/60 absolute right-2 top-2 z-10 h-7 gap-1 border px-2 text-[11px] backdrop-blur lg:hidden"
+          className="bg-background/80 border-border/60 absolute right-2 top-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" />
@@ -94,10 +100,12 @@ export function CoachDrawerBody({
         </div>
       </main>
 
-      {/* Sources rail — desktop only. */}
+      {/* Sources rail — xl+ only. lg viewports surface it via the
+          mobile chevron tray to keep the underlying /insights column
+          readable behind the narrowed drawer cap. */}
       <aside
         data-slot="coach-drawer-sources"
-        className="border-border/70 hidden h-full min-h-0 border-l lg:flex lg:flex-col"
+        className="border-border/70 hidden h-full min-h-0 border-l xl:flex xl:flex-col"
       >
         {sourcesRail}
       </aside>

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

@@ -134,7 +134,15 @@ export function CoachDrawer({
         showCloseButton
         data-slot="coach-drawer"
         className={cn(
-          "w-full p-0 sm:max-w-[720px] lg:max-w-[1080px]",
+          // Drawer keeps the dashboard context behind it. On laptops
+          // (1280-1366px viewports) the previous lg:max-w-[1080px] cap
+          // left only ~200-286px of underlying /insights visible — a
+          // takeover, not a sheet. Drop the lg cap to min(960px,75vw)
+          // so /insights always retains a readable column; restore
+          // the wider three-column layout at xl+ (≥1280px sources rail
+          // is hidden below xl by the body's lg:hidden chevron rules).
+          "w-full p-0 sm:max-w-[720px]",
+          "lg:!max-w-[min(960px,75vw)] xl:!max-w-[1080px]",
           "flex h-[100dvh] flex-col gap-0",
         )}
       >
@@ -260,7 +268,9 @@ export function CoachDrawer({
           <SheetContent
             side="right"
             data-slot="coach-drawer-sources-tray"
-            className="w-[88vw] max-w-[320px] p-0 lg:hidden"
+            // Sources rail is xl+ inline; on lg it's only available
+            // via this tray to match the narrowed drawer cap.
+            className="w-[88vw] max-w-[320px] p-0 xl:hidden"
           >
             <SheetHeader className="border-border/70 border-b p-3">
               <SheetTitle className="text-sm">