diff --git a/packages/web/src/__tests__/setup.ts b/packages/web/src/__tests__/setup.ts
index f149f27ae..533b774d3 100644
--- a/packages/web/src/__tests__/setup.ts
+++ b/packages/web/src/__tests__/setup.ts
@@ -1 +1,19 @@
 import "@testing-library/jest-dom/vitest";
+
+// jsdom does not implement window.matchMedia. Provide a minimal stub so
+// components that call useMediaQuery (e.g. Dashboard) work in unit tests.
+// The stub always returns `false` (non-matching), which keeps tests in the
+// desktop/non-mobile rendering path and avoids spurious re-renders.
+Object.defineProperty(window, "matchMedia", {
+  writable: true,
+  value: (query: string) => ({
+    matches: false,
+    media: query,
+    onchange: null,
+    addListener: () => {},
+    removeListener: () => {},
+    addEventListener: () => {},
+    removeEventListener: () => {},
+    dispatchEvent: () => false,
+  }),
+});
diff --git a/packages/web/src/app/globals.css b/packages/web/src/app/globals.css
index 3bf74e6ce..705c4474b 100644
--- a/packages/web/src/app/globals.css
+++ b/packages/web/src/app/globals.css
@@ -1818,6 +1818,93 @@ html.light .xterm .xterm-viewport:hover::-webkit-scrollbar-thumb:active {
 
 /* Card glow effects removed for Linear-clean look */
 
+/* ── Mobile accordion board ─────────────────────────────────────────── */
+
+.accordion-board {
+  display: flex;
+  flex-direction: column;
+  gap: 0;
+  margin-top: 8px;
+}
+
+.accordion-section {
+  border: 1px solid var(--color-border-default);
+  background: var(--color-bg-surface);
+  overflow: hidden;
+  transition: background 0.15s ease;
+}
+
+.accordion-section + .accordion-section {
+  margin-top: 6px;
+}
+
+.accordion-header {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  width: 100%;
+  min-height: 44px;
+  padding: 0 14px;
+  background: none;
+  border: none;
+  cursor: pointer;
+  text-align: left;
+  color: var(--color-text-primary);
+  transition: background 0.12s ease;
+}
+
+.accordion-header:hover {
+  background: var(--color-bg-hover);
+}
+
+.accordion-header__dot {
+  width: 8px;
+  height: 8px;
+  border-radius: 999px;
+  flex-shrink: 0;
+}
+
+.accordion-header__label {
+  font-size: 14px;
+  font-weight: 600;
+  flex: 1;
+  color: var(--color-text-primary);
+}
+
+.accordion-header__count {
+  font-size: 12px;
+  font-weight: 500;
+  min-width: 20px;
+  padding: 2px 6px;
+  background: color-mix(in srgb, var(--color-border-default) 60%, transparent);
+  border-radius: 999px;
+  text-align: center;
+  color: var(--color-text-secondary);
+  font-variant-numeric: tabular-nums;
+}
+
+.accordion-header__chevron {
+  font-size: 10px;
+  color: var(--color-text-tertiary);
+  flex-shrink: 0;
+  transition: transform 0.25s ease;
+}
+
+/* Accordion body: hidden when collapsed, visible when expanded */
+.accordion-body {
+  display: grid;
+  grid-template-rows: 1fr;
+  transition: grid-template-rows 0.25s ease;
+}
+
+.accordion-section--collapsed .accordion-body {
+  grid-template-rows: 0fr;
+}
+
+.accordion-section--collapsed .accordion-body > * {
+  overflow: hidden;
+}
+
 @media (max-width: 960px) {
   .dashboard-hero__content {
     padding: 12px 14px;
@@ -1997,10 +2084,9 @@ html.light .xterm .xterm-viewport:hover::-webkit-scrollbar-thumb:active {
     max-height: 400px;
   }
 
+  /* Hide the "Attention Board" heading + legend on mobile — accordion provides its own headers */
   .board-section-head {
-    flex-direction: column;
-    align-items: flex-start;
-    gap: 8px;
+    display: none;
   }
 
   .board-section-head__legend {
diff --git a/packages/web/src/components/AttentionZone.tsx b/packages/web/src/components/AttentionZone.tsx
index 420b95744..764b40954 100644
--- a/packages/web/src/components/AttentionZone.tsx
+++ b/packages/web/src/components/AttentionZone.tsx
@@ -11,6 +11,10 @@ interface AttentionZoneProps {
   onKill?: (sessionId: string) => void;
   onMerge?: (prNumber: number) => void;
   onRestore?: (sessionId: string) => void;
+  /** Accordion mode: whether this section is collapsed (mobile only) */
+  collapsed?: boolean;
+  /** Accordion mode: called when the header is tapped to toggle */
+  onToggle?: () => void;
 }
 
 const zoneConfig: Record<
@@ -56,6 +60,11 @@ const zoneConfig: Record<
 /**
  * Kanban column — always renders (even when empty) to preserve
  * the board shape. Cards scroll independently within each column.
+ *
+ * When `collapsed` and `onToggle` are provided the component renders
+ * in accordion mode (mobile): a 44 px tappable header only, with the
+ * card list hidden. Empty sections in accordion mode omit the dashed
+ * placeholder entirely — just the single-line header is shown.
  */
 function AttentionZoneView({
   level,
@@ -64,8 +73,51 @@ function AttentionZoneView({
   onKill,
   onMerge,
   onRestore,
+  collapsed,
+  onToggle,
 }: AttentionZoneProps) {
   const config = zoneConfig[level];
+  const isAccordion = onToggle !== undefined;
+
+  if (isAccordion) {
+    return (
+      <div
+        className={`accordion-section${collapsed ? " accordion-section--collapsed" : " accordion-section--expanded"}`}
+        data-level={level}
+      >
+        <button
+          type="button"
+          className="accordion-header"
+          onClick={onToggle}
+          aria-expanded={!collapsed}
+        >
+          <span className="accordion-header__dot" style={{ background: config.color }} />
+          <span className="accordion-header__label">{config.label}</span>
+          <span className="accordion-header__count">{sessions.length}</span>
+          <span className="accordion-header__chevron" aria-hidden="true">
+            {collapsed ? "▶" : "▼"}
+          </span>
+        </button>
+
+        <div className="accordion-body">
+          {sessions.length > 0 && (
+            <div className="flex flex-col gap-2 p-3">
+              {sessions.map((session) => (
+                <SessionCard
+                  key={session.id}
+                  session={session}
+                  onSend={onSend}
+                  onKill={onKill}
+                  onMerge={onMerge}
+                  onRestore={onRestore}
+                />
+              ))}
+            </div>
+          )}
+        </div>
+      </div>
+    );
+  }
 
   return (
     <div className="kanban-column" data-level={level}>
@@ -105,6 +157,8 @@ function AttentionZoneView({
 function areAttentionZonePropsEqual(prev: AttentionZoneProps, next: AttentionZoneProps): boolean {
   return (
     prev.level === next.level &&
+    prev.collapsed === next.collapsed &&
+    prev.onToggle === next.onToggle &&
     prev.onSend === next.onSend &&
     prev.onKill === next.onKill &&
     prev.onMerge === next.onMerge &&
diff --git a/packages/web/src/components/Dashboard.tsx b/packages/web/src/components/Dashboard.tsx
index ad67cd9ce..cf0053523 100644
--- a/packages/web/src/components/Dashboard.tsx
+++ b/packages/web/src/components/Dashboard.tsx
@@ -2,6 +2,7 @@
 
 import { useCallback, useEffect, useMemo, useState } from "react";
 import { useSearchParams } from "next/navigation";
+import { useMediaQuery } from "@/hooks/useMediaQuery";
 import {
   type DashboardSession,
   type DashboardStats,
@@ -32,6 +33,8 @@ interface DashboardProps {
 }
 
 const KANBAN_LEVELS = ["working", "pending", "review", "respond", "merge"] as const;
+/** Urgency-first order for the mobile accordion (reversed from desktop) */
+const MOBILE_KANBAN_ORDER = ["respond", "merge", "review", "pending", "working"] as const;
 const EMPTY_ORCHESTRATORS: DashboardOrchestratorLink[] = [];
 
 function mergeOrchestrators(
@@ -71,6 +74,8 @@ export function Dashboard({
   const [spawnErrors, setSpawnErrors] = useState<Record<string, string>>({});
   const [sidebarCollapsed, setSidebarCollapsed] = useState(false);
   const [mobileMenuOpen, setMobileMenuOpen] = useState(false);
+  const isMobile = useMediaQuery(767);
+  const [expandedLevel, setExpandedLevel] = useState<AttentionLevel | null>(null);
   const showSidebar = projects.length > 1;
   const allProjectsView = showSidebar && projectId === undefined;
 
@@ -102,6 +107,14 @@ export function Dashboard({
     return zones;
   }, [displaySessions]);
 
+  // Auto-expand the most urgent non-empty section when switching to mobile
+  // or when session data first loads. Only runs when isMobile is true.
+  useEffect(() => {
+    if (!isMobile) return;
+    const firstNonEmpty = MOBILE_KANBAN_ORDER.find((level) => grouped[level].length > 0) ?? null;
+    setExpandedLevel(firstNonEmpty);
+  }, [isMobile, grouped]);
+
   const sessionsByProject = useMemo(() => {
     const groupedSessions = new Map<string, DashboardSession[]>();
     for (const session of sessions) {
@@ -417,19 +430,40 @@ export function Dashboard({
                 <BoardLegendItem label="Ready to land" tone="var(--color-status-ready)" />
               </div>
             </div>
-            <div className="kanban-board">
-              {KANBAN_LEVELS.map((level) => (
-                <AttentionZone
-                  key={level}
-                  level={level}
-                  sessions={grouped[level]}
-                  onSend={handleSend}
-                  onKill={handleKill}
-                  onMerge={handleMerge}
-                  onRestore={handleRestore}
-                />
-              ))}
-            </div>
+
+            {isMobile ? (
+              <div className="accordion-board">
+                {MOBILE_KANBAN_ORDER.map((level) => (
+                  <AttentionZone
+                    key={level}
+                    level={level}
+                    sessions={grouped[level]}
+                    onSend={handleSend}
+                    onKill={handleKill}
+                    onMerge={handleMerge}
+                    onRestore={handleRestore}
+                    collapsed={expandedLevel !== level}
+                    onToggle={() =>
+                      setExpandedLevel((current) => (current === level ? null : level))
+                    }
+                  />
+                ))}
+              </div>
+            ) : (
+              <div className="kanban-board">
+                {KANBAN_LEVELS.map((level) => (
+                  <AttentionZone
+                    key={level}
+                    level={level}
+                    sessions={grouped[level]}
+                    onSend={handleSend}
+                    onKill={handleKill}
+                    onMerge={handleMerge}
+                    onRestore={handleRestore}
+                  />
+                ))}
+              </div>
+            )}
           </div>
         )}