diff --git a/src/app/insights/blutdruck/page.tsx b/src/app/insights/blutdruck/page.tsx
index 84e74486f..046bf3171 100644
--- a/src/app/insights/blutdruck/page.tsx
+++ b/src/app/insights/blutdruck/page.tsx
@@ -11,6 +11,7 @@ import { useTranslations } from "@/lib/i18n/context";
 import { useInsightsLayoutPrefs } from "@/hooks/use-insights-layout-prefs";
 import { Button } from "@/components/ui/button";
 import { EmptyState } from "@/components/ui/empty-state";
+import { CoachLaunchButton } from "@/components/insights/coach-launch-button";
 import { InsightStatusCard } from "@/components/insights/insight-status-card";
 import { SubPageShell } from "@/components/insights/sub-page-shell";
 import { getBpTargets } from "@/lib/analytics/bp-targets";
@@ -139,6 +140,8 @@ export default function InsightsBlutdruckPage() {
         updatedAt={status?.updatedAt ?? null}
         loading={isStatusLoading}
       />
+
+      <CoachLaunchButton />
     </SubPageShell>
   );
 }
diff --git a/src/app/insights/bmi/page.tsx b/src/app/insights/bmi/page.tsx
index e1ef69dab..314a5ae1c 100644
--- a/src/app/insights/bmi/page.tsx
+++ b/src/app/insights/bmi/page.tsx
@@ -11,6 +11,7 @@ import { useTranslations } from "@/lib/i18n/context";
 import { useInsightsLayoutPrefs } from "@/hooks/use-insights-layout-prefs";
 import { Button } from "@/components/ui/button";
 import { EmptyState } from "@/components/ui/empty-state";
+import { CoachLaunchButton } from "@/components/insights/coach-launch-button";
 import { InsightStatusCard } from "@/components/insights/insight-status-card";
 import { SubPageShell } from "@/components/insights/sub-page-shell";
 import type { DataSummary } from "@/lib/analytics/trends";
@@ -140,6 +141,8 @@ export default function InsightsBmiPage() {
         updatedAt={status?.updatedAt ?? null}
         loading={isStatusLoading}
       />
+
+      <CoachLaunchButton />
     </SubPageShell>
   );
 }
diff --git a/src/app/insights/gewicht/page.tsx b/src/app/insights/gewicht/page.tsx
index 6d9003f5a..726c7ebbc 100644
--- a/src/app/insights/gewicht/page.tsx
+++ b/src/app/insights/gewicht/page.tsx
@@ -11,6 +11,7 @@ import { useTranslations } from "@/lib/i18n/context";
 import { useInsightsLayoutPrefs } from "@/hooks/use-insights-layout-prefs";
 import { Button } from "@/components/ui/button";
 import { EmptyState } from "@/components/ui/empty-state";
+import { CoachLaunchButton } from "@/components/insights/coach-launch-button";
 import { InsightStatusCard } from "@/components/insights/insight-status-card";
 import { SubPageShell } from "@/components/insights/sub-page-shell";
 import { buildWeightBandsFromHeight } from "@/lib/analytics/value-bands";
@@ -117,6 +118,8 @@ export default function InsightsGewichtPage() {
         updatedAt={status?.updatedAt ?? null}
         loading={isStatusLoading}
       />
+
+      <CoachLaunchButton />
     </SubPageShell>
   );
 }
diff --git a/src/app/insights/layout.tsx b/src/app/insights/layout.tsx
index 6db91e360..25b0b4cb7 100644
--- a/src/app/insights/layout.tsx
+++ b/src/app/insights/layout.tsx
@@ -1,6 +1,8 @@
 import type { ReactNode } from "react";
 
 import { InsightsLayoutShell } from "@/components/insights/insights-layout-shell";
+import { LayoutCoachMount } from "@/components/insights/layout-coach-mount";
+import { CoachLaunchProvider } from "@/lib/insights/coach-launch-context";
 
 /**
  * v1.4.25 W4 — shared layout for the routed `/insights` sub-pages.
@@ -10,12 +12,20 @@ import { InsightsLayoutShell } from "@/components/insights/insights-layout-shell
  * into a sub-page. The actual page body still owns its own data fetches
  * — the layout is a thin presentational frame.
  *
- * Critical design rule (Marc directive 2026-05-11):
- *   The `<CoachDrawer>` is NOT mounted in this layout. It stays inside
- *   `src/app/insights/page.tsx` body so navigating into a sub-page
- *   unmounts the drawer (matches the Apple Health convention that AI/
- *   coach surfaces only live on the overview, never on a metric page).
+ * v1.4.27 R3d MB4 — the Coach drawer now mounts here (above the routed
+ * children) inside a `<CoachLaunchProvider>` so navigating into a sub-
+ * page no longer unmounts the drawer. Every sub-page mounts a
+ * `<CoachLaunchButton>` that calls `askCoach()` on the same context;
+ * the mother `/insights/page.tsx` consumes the same hook for its hero
+ * strip + suggested-prompt chips. Decision F (audit MA3) drove the
+ * promotion: a mobile user who navigates from `/insights` to
+ * `/insights/blutdruck` keeps a one-tap path back into the Coach.
  */
 export default function InsightsLayout({ children }: { children: ReactNode }) {
-  return <InsightsLayoutShell>{children}</InsightsLayoutShell>;
+  return (
+    <CoachLaunchProvider>
+      <InsightsLayoutShell>{children}</InsightsLayoutShell>
+      <LayoutCoachMount />
+    </CoachLaunchProvider>
+  );
 }
diff --git a/src/app/insights/medikamente/page.tsx b/src/app/insights/medikamente/page.tsx
index ff982be9e..022a3fbaf 100644
--- a/src/app/insights/medikamente/page.tsx
+++ b/src/app/insights/medikamente/page.tsx
@@ -12,6 +12,7 @@ import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
 import { EmptyState } from "@/components/ui/empty-state";
 import { Progress } from "@/components/ui/progress";
 import { ComplianceHeatmap } from "@/components/charts/compliance-heatmap";
+import { CoachLaunchButton } from "@/components/insights/coach-launch-button";
 import { InsightStatusCard } from "@/components/insights/insight-status-card";
 import { SubPageShell } from "@/components/insights/sub-page-shell";
 import { TherapyTimeline } from "@/components/insights/therapy-timeline";
@@ -225,6 +226,8 @@ export default function InsightsMedikamentePage() {
           without an active GLP-1 medication, so the page collapses
           back to the compliance grid for everyone else. */}
       <TherapyTimeline />
+
+      <CoachLaunchButton />
     </SubPageShell>
   );
 }
diff --git a/src/app/insights/page.tsx b/src/app/insights/page.tsx
index 62b698b49..e563ddbe6 100644
--- a/src/app/insights/page.tsx
+++ b/src/app/insights/page.tsx
@@ -1,6 +1,5 @@
 "use client";
 
-import { useState } from "react";
 import { useQuery } from "@tanstack/react-query";
 import Link from "next/link";
 import { Loader2, TrendingUp } from "lucide-react";
@@ -12,10 +11,10 @@ import { EmptyState } from "@/components/ui/empty-state";
 import { InsightAdvisorCard } from "@/components/insights/insight-advisor-card";
 import { HeroStrip } from "@/components/insights/hero-strip";
 import { DailyBriefing } from "@/components/insights/daily-briefing";
-import { CoachDrawer } from "@/components/insights/coach-panel/coach-drawer";
 import { TrendsRow } from "@/components/insights/trends-row";
 import { CorrelationRow } from "@/components/insights/correlation-row";
 import { useInsightsAdvisorQuery } from "@/components/insights/use-insights-advisor";
+import { useCoachLaunch } from "@/lib/insights/coach-launch-context";
 import type { CorrelationResult } from "@/lib/insights/correlations";
 import { toWeekISO } from "@/lib/insights/week-iso";
 import type { DataSummary } from "@/lib/analytics/trends";
@@ -96,12 +95,12 @@ export default function InsightsPage() {
   const { isAuthenticated, user } = useAuth();
   const { t } = useTranslations();
 
-  // CoachDrawer state. The hero strip's "Ask the coach" button +
-  // suggested-prompt chips toggle the drawer here; the drawer ingests
-  // `coachPrefill` once on open and resets on close so the next open
-  // starts blank.
-  const [coachOpen, setCoachOpen] = useState<boolean>(false);
-  const [coachPrefill, setCoachPrefill] = useState<string | null>(null);
+  // v1.4.27 R3d MB4 — Coach drawer state lives in the layout-level
+  // `<CoachLaunchProvider>` so every routed sub-page can reach it.
+  // The hero strip + suggested-prompt chips call `askCoach(prefill)`
+  // on the same context, and the drawer itself is mounted next to
+  // the provider in `src/app/insights/layout.tsx`.
+  const coachLaunch = useCoachLaunch();
 
   const { data, isLoading } = useQuery({
     queryKey: ["insights", "comprehensive"],
@@ -183,14 +182,16 @@ export default function InsightsPage() {
         briefing={briefingPayload}
         updatedAt={heroStripUpdatedAt}
         userName={heroGreetingName}
-        onAskCoach={(prefill?: string) => {
-          setCoachPrefill(prefill ?? null);
-          setCoachOpen(true);
-        }}
-        onPickPrompt={(prompt) => {
-          setCoachPrefill(prompt);
-          setCoachOpen(true);
-        }}
+        onAskCoach={
+          coachLaunch
+            ? (prefill?: string) => coachLaunch.askCoach(prefill ?? null)
+            : undefined
+        }
+        onPickPrompt={
+          coachLaunch
+            ? (prompt) => coachLaunch.askCoach(prompt)
+            : undefined
+        }
         weeklyReportReady={weeklyReportReady}
         weeklyReportHref={currentWeekHref}
         healthScore={analytics?.healthScore ?? undefined}
@@ -217,12 +218,6 @@ export default function InsightsPage() {
         cachedAt={advisor.payload?.cachedAt ?? null}
         legacyPayload={advisor.payload?.legacyPayload ?? false}
       />
-
-      <CoachDrawer
-        open={coachOpen}
-        onOpenChange={setCoachOpen}
-        prefill={coachPrefill}
-      />
     </div>
   );
 }
diff --git a/src/app/insights/puls/page.tsx b/src/app/insights/puls/page.tsx
index 2a031d43f..d8e5f76b4 100644
--- a/src/app/insights/puls/page.tsx
+++ b/src/app/insights/puls/page.tsx
@@ -11,6 +11,7 @@ import { useTranslations } from "@/lib/i18n/context";
 import { useInsightsLayoutPrefs } from "@/hooks/use-insights-layout-prefs";
 import { Button } from "@/components/ui/button";
 import { EmptyState } from "@/components/ui/empty-state";
+import { CoachLaunchButton } from "@/components/insights/coach-launch-button";
 import { InsightStatusCard } from "@/components/insights/insight-status-card";
 import { SubPageShell } from "@/components/insights/sub-page-shell";
 import { Vo2MaxChartRow } from "@/components/insights/vo2-max-chart-row";
@@ -164,6 +165,8 @@ export default function InsightsPulsPage() {
         compareBaseline={compareBaseline}
         userTimezone={user?.timezone}
       />
+
+      <CoachLaunchButton />
     </SubPageShell>
   );
 }
diff --git a/src/app/insights/schlaf/page.tsx b/src/app/insights/schlaf/page.tsx
index 596c0941c..be0bcc06d 100644
--- a/src/app/insights/schlaf/page.tsx
+++ b/src/app/insights/schlaf/page.tsx
@@ -8,6 +8,7 @@ import { useAuth } from "@/hooks/use-auth";
 import { useTranslations } from "@/lib/i18n/context";
 import { Button } from "@/components/ui/button";
 import { EmptyState } from "@/components/ui/empty-state";
+import { CoachLaunchButton } from "@/components/insights/coach-launch-button";
 import { SleepOverview } from "@/components/insights/sleep-overview";
 import { SubPageShell } from "@/components/insights/sub-page-shell";
 import type { DataSummary } from "@/lib/analytics/trends";
@@ -79,6 +80,8 @@ export default function InsightsSchlafPage() {
       description={t("insights.sleep.description")}
     >
       <SleepOverview />
+
+      <CoachLaunchButton />
     </SubPageShell>
   );
 }
diff --git a/src/app/insights/stimmung/page.tsx b/src/app/insights/stimmung/page.tsx
index 21df0ed7b..d4889c2dc 100644
--- a/src/app/insights/stimmung/page.tsx
+++ b/src/app/insights/stimmung/page.tsx
@@ -11,6 +11,7 @@ import { useTranslations } from "@/lib/i18n/context";
 import { useInsightsLayoutPrefs } from "@/hooks/use-insights-layout-prefs";
 import { Button } from "@/components/ui/button";
 import { EmptyState } from "@/components/ui/empty-state";
+import { CoachLaunchButton } from "@/components/insights/coach-launch-button";
 import { InsightStatusCard } from "@/components/insights/insight-status-card";
 import { SubPageShell } from "@/components/insights/sub-page-shell";
 
@@ -99,6 +100,8 @@ export default function InsightsStimmungPage() {
         updatedAt={status?.updatedAt ?? null}
         loading={isStatusLoading}
       />
+
+      <CoachLaunchButton />
     </SubPageShell>
   );
 }
diff --git a/src/components/insights/coach-launch-button.tsx b/src/components/insights/coach-launch-button.tsx
new file mode 100644
index 000000000..69454539c
--- /dev/null
+++ b/src/components/insights/coach-launch-button.tsx
@@ -0,0 +1,93 @@
+"use client";
+
+import { Sparkles } from "lucide-react";
+
+import { Button } from "@/components/ui/button";
+import { cn } from "@/lib/utils";
+import { useTranslations } from "@/lib/i18n/context";
+import { useCoachLaunch } from "@/lib/insights/coach-launch-context";
+
+/**
+ * v1.4.27 R3d MB4 — Coach launch button.
+ *
+ * Decision F: every routed Insights sub-page mounts this button so the
+ * Coach drawer (mounted at the layout root) is always reachable. The
+ * button renders as a sticky-bottom FAB on `<lg` viewports (so a phone
+ * user always sees it within thumb range) and as an inline header
+ * action on `lg+` (where the desktop drawer slides in from the right
+ * edge and the FAB would overlap the chart legend).
+ *
+ * The button is a thin wrapper around `useCoachLaunch()` — it only
+ * renders when the context provider is mounted (so dropping the button
+ * onto a non-Insights page is a no-op rather than a crash).
+ */
+export interface CoachLaunchButtonProps {
+  /** Optional override for the visual label. Defaults to the shared CTA. */
+  label?: string;
+  /** Optional prefill seed for the next Coach turn. */
+  prefill?: string;
+  /** Optional className passthrough for inline overrides. */
+  className?: string;
+}
+
+export function CoachLaunchButton({
+  label,
+  prefill,
+  className,
+}: CoachLaunchButtonProps) {
+  const { t } = useTranslations();
+  const launch = useCoachLaunch();
+
+  if (!launch) {
+    // The button only makes sense beneath the provider. Render nothing
+    // so the sub-page doesn't paint a dead control.
+    return null;
+  }
+
+  const accessibleLabel = label ?? t("insights.heroActionAskCoach");
+
+  return (
+    <>
+      {/* Sticky FAB on `<lg` viewports — pinned to the bottom-right so
+          the user's thumb always finds it. `bottom-20` clears the
+          mobile bottom navigation; `safe-area-inset-bottom` plus the
+          existing app shell padding keep it clear of the iOS home bar.
+          Hidden on `lg+` where the inline button below takes over. */}
+      <Button
+        type="button"
+        size="lg"
+        data-slot="coach-launch-fab"
+        onClick={() => launch.askCoach(prefill ?? null)}
+        aria-label={accessibleLabel}
+        title={accessibleLabel}
+        className={cn(
+          "fixed right-4 bottom-20 z-40 h-12 rounded-full px-4 shadow-lg",
+          "from-dracula-purple to-dracula-pink bg-gradient-to-br text-white",
+          "hover:from-dracula-purple/90 hover:to-dracula-pink/90",
+          "lg:hidden",
+          className,
+        )}
+      >
+        <Sparkles className="size-4" aria-hidden="true" />
+        <span>{accessibleLabel}</span>
+      </Button>
+      {/* Inline header-style action on `lg+`. Lives in the page body so
+          it picks up the sub-page layout's spacing instead of fighting
+          a sticky header overlay. */}
+      <Button
+        type="button"
+        variant="outline"
+        size="sm"
+        data-slot="coach-launch-inline"
+        onClick={() => launch.askCoach(prefill ?? null)}
+        className={cn(
+          "hidden h-10 gap-2 self-end lg:inline-flex",
+          className,
+        )}
+      >
+        <Sparkles className="size-4" aria-hidden="true" />
+        <span>{accessibleLabel}</span>
+      </Button>
+    </>
+  );
+}
diff --git a/src/components/insights/layout-coach-mount.tsx b/src/components/insights/layout-coach-mount.tsx
new file mode 100644
index 000000000..b93f953b5
--- /dev/null
+++ b/src/components/insights/layout-coach-mount.tsx
@@ -0,0 +1,26 @@
+"use client";
+
+import { CoachDrawer } from "@/components/insights/coach-panel/coach-drawer";
+import { useCoachLaunch } from "@/lib/insights/coach-launch-context";
+
+/**
+ * v1.4.27 R3d MB4 — bridge between the layout-level
+ * `<CoachLaunchProvider>` and the Coach drawer mount.
+ *
+ * The layout file is a server component (it lives next to other server
+ * components and feeds the `metadata` chain), so the actual `useState`
+ * + `<CoachDrawer>` consumer has to live inside a client island. This
+ * file is intentionally tiny — its only job is to read the context and
+ * render the drawer at the layout's mount site.
+ */
+export function LayoutCoachMount() {
+  const launch = useCoachLaunch();
+  if (!launch) return null;
+  return (
+    <CoachDrawer
+      open={launch.open}
+      onOpenChange={launch.setOpen}
+      prefill={launch.prefill}
+    />
+  );
+}
diff --git a/src/lib/insights/__tests__/coach-launch-context.test.tsx b/src/lib/insights/__tests__/coach-launch-context.test.tsx
new file mode 100644
index 000000000..4a8fdc5fd
--- /dev/null
+++ b/src/lib/insights/__tests__/coach-launch-context.test.tsx
@@ -0,0 +1,71 @@
+import { describe, it, expect } from "vitest";
+import { renderToStaticMarkup } from "react-dom/server";
+
+import {
+  CoachLaunchProvider,
+  useCoachLaunch,
+} from "../coach-launch-context";
+
+/**
+ * v1.4.27 R3d MB4 — Coach launch context smoke contract.
+ *
+ * The project's test convention is `renderToStaticMarkup` (no
+ * `@testing-library/react` dependency). We can't simulate interaction
+ * inside SSR, but we can verify:
+ *   1. The provider mounts and renders its children.
+ *   2. The hook returns a value-shape (open, prefill, askCoach,
+ *      setOpen) when called beneath the provider.
+ *   3. The hook returns `null` when called outside the provider —
+ *      consumers degrade gracefully (e.g. the launch button renders
+ *      nothing rather than crashing).
+ */
+
+function Probe({ output }: { output: string[] }) {
+  const launch = useCoachLaunch();
+  if (!launch) {
+    output.push("null");
+    return null;
+  }
+  output.push(
+    JSON.stringify({
+      hasAskCoach: typeof launch.askCoach,
+      hasSetOpen: typeof launch.setOpen,
+      open: launch.open,
+      prefill: launch.prefill,
+    }),
+  );
+  return <span data-slot="probe-output">{output.join(",")}</span>;
+}
+
+describe("CoachLaunchProvider", () => {
+  it("returns null when consumed outside the provider", () => {
+    const output: string[] = [];
+    renderToStaticMarkup(<Probe output={output} />);
+    expect(output).toEqual(["null"]);
+  });
+
+  it("exposes the full context shape when consumed beneath the provider", () => {
+    const output: string[] = [];
+    renderToStaticMarkup(
+      <CoachLaunchProvider>
+        <Probe output={output} />
+      </CoachLaunchProvider>,
+    );
+    expect(output).toHaveLength(1);
+    const parsed = JSON.parse(output[0]);
+    expect(parsed.hasAskCoach).toBe("function");
+    expect(parsed.hasSetOpen).toBe("function");
+    expect(parsed.open).toBe(false);
+    expect(parsed.prefill).toBeNull();
+  });
+
+  it("renders the children inside the provider mount", () => {
+    const html = renderToStaticMarkup(
+      <CoachLaunchProvider>
+        <div data-slot="child-mount">child</div>
+      </CoachLaunchProvider>,
+    );
+    expect(html).toContain('data-slot="child-mount"');
+    expect(html).toContain("child");
+  });
+});
diff --git a/src/lib/insights/coach-launch-context.tsx b/src/lib/insights/coach-launch-context.tsx
new file mode 100644
index 000000000..3dbd14c69
--- /dev/null
+++ b/src/lib/insights/coach-launch-context.tsx
@@ -0,0 +1,103 @@
+"use client";
+
+import {
+  createContext,
+  useCallback,
+  useContext,
+  useMemo,
+  useState,
+  type ReactNode,
+} from "react";
+
+/**
+ * v1.4.27 R3d MB4 — Coach launch context.
+ *
+ * Until v1.4.27 the Coach drawer was mounted inline on
+ * `/insights/page.tsx` body, which meant navigating to a routed
+ * sub-page (`/insights/blutdruck`, etc.) unmounted the drawer and
+ * removed every entry point to the Coach. The MA3 audit + Decision F
+ * promoted the drawer up to `/insights/layout.tsx` so every routed
+ * Insights surface can launch it.
+ *
+ * Shape:
+ *   - `<CoachLaunchProvider>` owns the drawer's open / prefill state
+ *     and renders the children beneath the launch surface.
+ *   - `useCoachLaunch()` returns `{ open, askCoach, setOpen, prefill }`
+ *     so any descendant can open the drawer with an optional prefill
+ *     string (the hero-strip suggested-prompt chips feed prefills;
+ *     the sticky `<CoachLaunchButton>` opens without one).
+ *
+ * The provider is intentionally tiny — the actual drawer mount sits
+ * next to it in the layout, reading the same state via the hook.
+ */
+export interface CoachLaunchScope {
+  /**
+   * Optional metric the user is looking at when they open the Coach.
+   * Reserved for v1.4.28 so the drawer can pre-narrow the source rail
+   * to the active metric; ignored in v1.4.27.
+   */
+  metric?: string;
+}
+
+interface CoachLaunchValue {
+  /** Whether the Coach drawer is currently open. */
+  open: boolean;
+  /** Current prefill string (or null when the next open should start blank). */
+  prefill: string | null;
+  /** Open the drawer with an optional prefill + scope hint. */
+  askCoach: (prefill?: string | null, scope?: CoachLaunchScope) => void;
+  /** Direct setter for the open state — the drawer consumes this. */
+  setOpen: (next: boolean) => void;
+}
+
+const CoachLaunchContext = createContext<CoachLaunchValue | null>(null);
+
+export interface CoachLaunchProviderProps {
+  children: ReactNode;
+}
+
+export function CoachLaunchProvider({ children }: CoachLaunchProviderProps) {
+  const [open, setOpen] = useState<boolean>(false);
+  const [prefill, setPrefill] = useState<string | null>(null);
+
+  const askCoach = useCallback(
+    (nextPrefill?: string | null, scope?: CoachLaunchScope) => {
+      // `scope` is currently reserved for v1.4.28 (metric-narrow on the
+      // sources rail). Accept the parameter today so the call sites
+      // don't need to change shape when the rail starts honouring it.
+      void scope;
+      setPrefill(nextPrefill ?? null);
+      setOpen(true);
+    },
+    [],
+  );
+
+  const handleSetOpen = useCallback((next: boolean) => {
+    setOpen(next);
+    if (!next) {
+      // Drop the prefill on close so the next open starts blank.
+      setPrefill(null);
+    }
+  }, []);
+
+  const value = useMemo<CoachLaunchValue>(
+    () => ({ open, prefill, askCoach, setOpen: handleSetOpen }),
+    [open, prefill, askCoach, handleSetOpen],
+  );
+
+  return (
+    <CoachLaunchContext.Provider value={value}>
+      {children}
+    </CoachLaunchContext.Provider>
+  );
+}
+
+/**
+ * Read the Coach launch context. Returns `null` when called outside a
+ * `<CoachLaunchProvider>` so consumer components can degrade gracefully
+ * (e.g. the hero strip's "Ask the coach" action stays disabled until
+ * the provider mounts).
+ */
+export function useCoachLaunch(): CoachLaunchValue | null {
+  return useContext(CoachLaunchContext);
+}