fix(coach): default to new chat and never dead-end on conversations

Reverse the resume-most-recent entry default: opening the Coach now lands
on the new-chat hero. The only exception is an unread coach-initiated
message (nudge-status `unread`), which auto-opens the most-recent thread so
the user sees what the Coach wrote. The `?c=<id>` deep-link is unchanged.

Add a dedicated, always-visible Conversations button (plus a New chat
button) to the page surface so reaching past conversations no longer hides
in the composer menu. The drawer's Conversations handoff now routes to
`/coach?view=conversations`, which opens the history drawer on arrival, so
the side-view to full-view path always shows the list instead of a blank
pane.

src/app/coach/page.tsx

@@ -2,11 +2,15 @@
 
 import { Suspense, useEffect } from "react";
 import { useRouter, useSearchParams } from "next/navigation";
+import { useQuery } from "@tanstack/react-query";
 
 import { CoachConversation } from "@/components/insights/coach-panel/coach-conversation";
+import type { CoachNudgeStatus } from "@/components/insights/layout-coach-fab";
 import { useCoachLaunch } from "@/lib/insights/coach-launch-context";
 import { useFeatureFlags } from "@/hooks/use-feature-flags";
 import { useDisableCoach } from "@/hooks/use-disable-coach";
+import { queryKeys } from "@/lib/query-keys";
+import { apiGet } from "@/lib/api/api-fetch";
 
 /**
  * v1.12.0 (Coach v2 #6) — full-page Coach conversation.
@@ -41,32 +45,53 @@ import { useDisableCoach } from "@/hooks/use-disable-coach";
  * the active conversation. All of that lives in `<CoachConversation>`'s
  * page branch, so the page stays a thin gating + sizing wrapper.
  *
- * v1.18.11 (W11, #67) — the page is now a deep-link target INTO a
- * conversation. A `?c=<id>` query param opens that specific thread on
- * mount; absent it, the page auto-opens the user's most-recent thread
- * (server-authoritative `updatedAt desc` head of the rail, so it lands the
- * same thread on web + mobile). Both feed `<CoachConversation>`'s existing
- * selection state — the dashboard Coach entry navigates straight into the
- * live conversation instead of a blank landing. `?c=new` (or no thread at
- * all) keeps the new-chat hero. The search-param read sits in a Suspense
- * child so the client-bailout never de-opts the route.
+ * v1.19.1 (C1/C5) — the Coach now DEFAULTS to the new-chat hero, reversing
+ * the v1.19.0 (W7) "always resume most-recent" default the maintainer
+ * disliked. Resolution order on mount:
+ *   - `?c=<id>` → open that specific thread (explicit deep-link, unchanged).
+ *   - `?c=new` or no param → the new-chat hero.
+ *   - `?view=conversations` → land on the new-chat hero AND open the
+ *     conversation-history drawer, so the drawer's "Conversations" handoff
+ *     (C5) never drops the user on a blank pane.
+ *   - EXCEPTION: when the Coach has proactively written an UNREAD message
+ *     (`/api/insights/coach/nudge-status` → `unread`), auto-open the
+ *     most-recent thread so the user lands on what the Coach said.
+ * The search-param read sits in a Suspense child so the client-bailout
+ * never de-opts the route.
  */
 function CoachPageBody() {
   const searchParams = useSearchParams();
   // `?c=new` is an explicit "start a fresh chat" escape hatch; any other
   // value is treated as a conversation id to open. A blank/absent param
-  // falls through to most-recent auto-open.
+  // defaults to the new-chat hero.
   const rawC = searchParams.get("c");
   const deepLinkedId = rawC && rawC !== "new" ? rawC : null;
+  // C5 — the drawer's "Conversations" handoff routes here with this flag so
+  // the page opens the history drawer on arrival instead of a blank hero.
+  const openConversations = searchParams.get("view") === "conversations";
+
+  // C1 exception — an unread coach-initiated message opens the most-recent
+  // conversation (which holds that proactive turn). Only consulted when the
+  // entry did not pin a specific thread or ask for a fresh chat / list.
+  const exceptionEligible = deepLinkedId === null && rawC !== "new";
+  const { data: nudge } = useQuery({
+    queryKey: queryKeys.coachNudgeStatus(),
+    queryFn: async (): Promise<CoachNudgeStatus> =>
+      apiGet<CoachNudgeStatus>("/api/insights/coach/nudge-status"),
+    enabled: exceptionEligible && !openConversations,
+    staleTime: 5 * 60 * 1000,
+  });
+  const hasUnreadCoachMessage = exceptionEligible && nudge?.unread === true;
 
   return (
     <CoachConversation
       surface="page"
       autoFocusComposer
       initialConversationId={deepLinkedId}
-      // Only auto-resolve most-recent when the entry did not pin a thread
-      // and did not ask for a fresh chat.
-      autoOpenMostRecent={deepLinkedId === null && rawC !== "new"}
+      // Default is the new-chat hero; only resume most-recent for the
+      // unread coach-initiated exception.
+      autoOpenMostRecent={hasUnreadCoachMessage}
+      openHistoryOnMount={openConversations}
     />
   );
 }

src/components/insights/coach-panel/__tests__/coach-conversation-deeplink.test.tsx

@@ -135,4 +135,25 @@ describe("<CoachConversation> page deep-link (#67)", () => {
     // though recent conversations exist in the cache.
     expect(html).toContain('data-slot="coach-hero"');
   });
+
+  // v1.19.1 (C2) — a dedicated, always-visible Conversations button on the
+  // page surface (not buried in the composer `+` menu).
+  it("renders the dedicated Conversations button on the page surface", () => {
+    const html = render(<CoachConversation surface="page" />, makeClient());
+    expect(html).toContain('data-slot="coach-page-conversations"');
+    expect(html).toContain('data-slot="coach-page-new-chat"');
+  });
+
+  // v1.19.1 (C5) — entering via the drawer handoff (`?view=conversations`)
+  // keeps the new-chat hero (no thread auto-resumed) while opening the
+  // history drawer; the toolbar + button stay present so the pane is never
+  // a blank dead-end.
+  it("keeps the hero and toolbar when opened with openHistoryOnMount", () => {
+    const html = render(
+      <CoachConversation surface="page" openHistoryOnMount />,
+      makeClient(),
+    );
+    expect(html).toContain('data-slot="coach-hero"');
+    expect(html).toContain('data-slot="coach-page-conversations"');
+  });
 });

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

@@ -3,7 +3,7 @@
 import { useEffect, useReducer, useState } from "react";
 import Link from "next/link";
 import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
-import { Plus, Settings, Sparkles } from "lucide-react";
+import { MessagesSquare, Plus, Settings, Sparkles } from "lucide-react";
 import { toast } from "sonner";
 
 import { Button } from "@/components/ui/button";
@@ -137,6 +137,13 @@ export interface CoachConversationProps {
    * "new chat" or thread switch is never overridden.
    */
   autoOpenMostRecent?: boolean;
+  /**
+   * v1.19.1 (C5) — page surface only: open the conversation-history drawer
+   * once on mount. The drawer's "Conversations" handoff routes to
+   * `/coach?view=conversations`, which sets this so the user always sees the
+   * conversation list on arrival instead of a blank new-chat pane.
+   */
+  openHistoryOnMount?: boolean;
 }
 
 export function CoachConversation({
@@ -152,6 +159,7 @@ export function CoachConversation({
   surface,
   initialConversationId,
   autoOpenMostRecent = false,
+  openHistoryOnMount = false,
 }: CoachConversationProps) {
   const { t } = useTranslations();
 
@@ -165,7 +173,12 @@ export function CoachConversation({
   // the composer's `+` actions menu. Replaces the old inline collapsible
   // rail + top rail-tray strip; the top header bar is gone entirely on the
   // page so the composer is the single control hub.
-  const [historyDrawerOpen, setHistoryDrawerOpen] = useState(false);
+  // v1.19.1 (C5) — seed the history drawer open when the page is entered via
+  // the drawer's "Conversations" handoff (`?view=conversations`), so the
+  // list is on screen immediately rather than a blank hero.
+  const [historyDrawerOpen, setHistoryDrawerOpen] = useState(
+    () => openHistoryOnMount,
+  );
   const [inputValue, setInputValue] = useResettableValue(prefill ?? "");
   // v1.16.4 — self-context backflow: `pendingAdopt` raises a quiet
   // offer to fold a clarifying-question answer back into the
@@ -484,6 +497,37 @@ export function CoachConversation({
         data-variant={surface}
         className={cn("flex min-h-0 flex-1 flex-col", className)}
       >
+        {/* v1.19.1 (C2) — a clear, always-visible "Conversations" button on
+            the page surface. The composer's `+` menu still carries the same
+            action, but the maintainer wanted an obvious, dedicated affordance
+            to reach past conversations rather than one buried in a menu. */}
+        <div
+          data-slot="coach-page-toolbar"
+          className="flex shrink-0 items-center justify-between gap-2 px-4 pt-2 sm:px-6"
+        >
+          <Button
+            type="button"
+            variant="ghost"
+            size="sm"
+            onClick={() => setHistoryDrawerOpen(true)}
+            data-slot="coach-page-conversations"
+            className="text-muted-foreground hover:text-foreground -ml-1 gap-1.5"
+          >
+            <MessagesSquare className="size-4" aria-hidden="true" />
+            {t("insights.coach.historyTitle")}
+          </Button>
+          <Button
+            type="button"
+            variant="ghost"
+            size="sm"
+            onClick={handleNewChat}
+            data-slot="coach-page-new-chat"
+            className="text-muted-foreground hover:text-foreground -mr-1 gap-1.5"
+          >
+            <Plus className="size-4" aria-hidden="true" />
+            {t("insights.coach.newChat")}
+          </Button>
+        </div>
         {heroActive ? (
           <CoachHero composer={composerNode} />
         ) : (

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

@@ -88,6 +88,17 @@ export function CoachDrawer({ open, onOpenChange, prefill }: CoachDrawerProps) {
     router.push("/coach");
   }, [onOpenChange, router]);
 
+  // v1.19.1 (C5) — the drawer's "Conversations" affordance hands off to the
+  // full page WITH the `?view=conversations` flag so the page opens the
+  // conversation-history drawer on arrival. Previously it shared
+  // `handleMaximize` and, after the v1.19.1 new-chat default (C1), landed on
+  // a blank hero with no list — the dead-end the maintainer reported.
+  const handleOpenConversations = useCallback(() => {
+    onOpenChange(false);
+    resetRef.current?.();
+    router.push("/coach?view=conversations");
+  }, [onOpenChange, router]);
+
   return (
     <Sheet open={open} onOpenChange={handleOpenChange}>
       <SheetContent
@@ -118,9 +129,10 @@ export function CoachDrawer({ open, onOpenChange, prefill }: CoachDrawerProps) {
           autoFocusComposer
           registerReset={registerReset}
           // v1.16.1 — the "Conversations" affordance hands off to the
-          // full-page route (same path as maximize) instead of opening
-          // the broken in-panel left tray.
-          onRequestFullView={handleMaximize}
+          // full-page route instead of opening the broken in-panel left
+          // tray. v1.19.1 (C5) — it now carries `?view=conversations` so the
+          // page opens the history list on arrival, never a blank hero.
+          onRequestFullView={handleOpenConversations}
           // Radix requires an accessible name + description on the
           // dialog content. Mount them through the title/description
           // render-props so the page can swap in a plain heading.