diff --git a/frontend/src/pages/Senders.jsx b/frontend/src/pages/Senders.jsx
index d7cdccf..6f74d63 100644
--- a/frontend/src/pages/Senders.jsx
+++ b/frontend/src/pages/Senders.jsx
@@ -1,69 +1,288 @@
-import { useEffect, useMemo, useState } from 'react';
-import { AnalyticsApi } from '../api/client.js';
+import { useEffect, useCallback, useRef, useState } from 'react';
+import { AnalyticsApi, SearchApi, EmailApi } from '../api/client.js';
 
-// Volume tiers, highest first.
-const TIERS = [
-  { key: '1000+', label: '1000+ emails', min: 1000, max: Infinity, accent: '#eb5757' },
-  { key: '500-1000', label: '500 – 1000', min: 500, max: 999, accent: '#f2994a' },
-  { key: '250-500', label: '250 – 500', min: 250, max: 499, accent: '#f2c94c' },
-  { key: '100-250', label: '100 – 250', min: 100, max: 249, accent: '#56ccf2' },
-  { key: '<100', label: 'Under 100', min: 0, max: 99, accent: '#6fcf97' }
-];
+// ── helpers ──────────────────────────────────────────────────────────────────
 
-const PER_TIER = 60; // cap visible blocks per tier to keep it light
+const fmtDate = (iso) => {
+  const d = new Date(iso);
+  const now = new Date();
+  const diffDays = (now - d) / 86400000;
+  if (diffDays < 1) return d.toLocaleTimeString([], { hour: '2-digit', minute: '2-digit' });
+  if (diffDays < 7) return d.toLocaleDateString([], { weekday: 'short' });
+  return d.toLocaleDateString([], { month: 'short', day: 'numeric' });
+};
 
-export default function Senders() {
-  const [senders, setSenders] = useState(null);
+const fmtSize = (b) => {
+  if (!b) return '';
+  if (b < 1024) return `${b} B`;
+  if (b < 1048576) return `${(b / 1024).toFixed(0)} KB`;
+  return `${(b / 1048576).toFixed(1)} MB`;
+};
 
-  useEffect(() => { AnalyticsApi.allSenders().then(setSenders).catch(() => setSenders([])); }, []);
+const PAGE_SIZE = 50;
 
-  const buckets = useMemo(() => {
-    const map = Object.fromEntries(TIERS.map((t) => [t.key, []]));
-    (senders || []).forEach((s) => {
-      const tier = TIERS.find((t) => s.emailCount >= t.min && s.emailCount <= t.max);
-      if (tier) map[tier.key].push(s);
-    });
-    Object.values(map).forEach((arr) => arr.sort((a, b) => b.emailCount - a.emailCount));
-    return map;
-  }, [senders]);
+// ── SenderList (left panel) ───────────────────────────────────────────────────
 
-  if (!senders) return <div className="page"><h2>Senders by Volume</h2><p className="muted">Loading…</p></div>;
+function SenderList({ senders, selectedId, onSelect, search, onSearch }) {
+  const filtered = senders.filter((s) => {
+    const q = search.toLowerCase();
+    return !q || (s.address + ' ' + (s.displayName ?? '')).toLowerCase().includes(q);
+  });
 
   return (
-    <div className="page senders-page">
-      <h2>Senders by Volume</h2>
-      <p className="muted">Who fills your inbox, grouped by how many emails they've sent you.</p>
-
-      {TIERS.map((tier) => {
-        const list = buckets[tier.key];
-        if (!list.length) return null;
-        const shown = list.slice(0, PER_TIER);
-        return (
-          <section className="tier" key={tier.key}>
-            <div className="tier-head">
-              <span className="tier-dot" style={{ background: tier.accent }} />
-              <h3>{tier.label}</h3>
-              <span className="tier-count">{list.length} sender{list.length === 1 ? '' : 's'}</span>
-            </div>
-            <div className="sender-blocks">
-              {shown.map((s) => (
-                <div className="sender-block" key={s.senderId} style={{ borderTopColor: tier.accent }}>
-                  <div className="sb-name" title={s.address}>{s.displayName || s.address}</div>
-                  <div className="sb-domain">{s.domain}</div>
-                  <div className="sb-stats">
-                    <span className="sb-count">{s.emailCount.toLocaleString()}</span>
-                    {s.unreadCount > 0 && <span className="sb-unread">{s.unreadCount} unread</span>}
-                    {s.hasUnsubscribe && <span className="sb-unsub">unsub</span>}
-                  </div>
-                </div>
-              ))}
-            </div>
-            {list.length > PER_TIER && <div className="muted tier-more">+ {list.length - PER_TIER} more</div>}
-          </section>
-        );
-      })}
-
-      {senders.length === 0 && <p className="muted">No senders yet — run a sync first.</p>}
+    <div className="sl-panel">
+      <div className="sl-search-wrap">
+        <input
+          className="sl-search"
+          type="search"
+          placeholder="Filter senders…"
+          value={search}
+          onChange={(e) => onSearch(e.target.value)}
+          aria-label="Filter senders"
+        />
+      </div>
+      <div className="sl-count">{filtered.length.toLocaleString()} sender{filtered.length !== 1 ? 's' : ''}</div>
+      <ul className="sl-list">
+        {filtered.map((s) => (
+          <li key={s.senderId}>
+            <button
+              className={`sl-item${selectedId === s.senderId ? ' sl-item--active' : ''}`}
+              onClick={() => onSelect(s)}
+            >
+              <div className="sl-name">{s.displayName || s.address}</div>
+              <div className="sl-addr">{s.displayName ? s.address : s.domain}</div>
+              <div className="sl-meta">
+                <span className="sl-email-count">{s.emailCount.toLocaleString()}</span>
+                {s.unreadCount > 0 && <span className="sl-unread">{s.unreadCount} unread</span>}
+              </div>
+            </button>
+          </li>
+        ))}
+      </ul>
+    </div>
+  );
+}
+
+// ── EmailDetail (full single-email view) ──────────────────────────────────────
+
+function EmailDetail({ email, onBack }) {
+  return (
+    <div className="sd-detail">
+      <button className="sd-back" onClick={onBack}>← Back to list</button>
+      <div className="sd-detail-header">
+        <div className="sd-detail-subject">{email.subject || '(no subject)'}</div>
+        <div className="sd-detail-meta">
+          <span>{email.senderDisplayName || email.senderAddress}</span>
+          <span className="sd-detail-sep">·</span>
+          <span>{new Date(email.sentAtUtc).toLocaleString()}</span>
+          {email.sizeEstimateBytes > 0 && (
+            <>
+              <span className="sd-detail-sep">·</span>
+              <span>{fmtSize(email.sizeEstimateBytes)}</span>
+            </>
+          )}
+        </div>
+      </div>
+      {email.snippet && (
+        <div className="sd-snippet">{email.snippet}</div>
+      )}
+      <div className="sd-detail-actions">
+        <button
+          className="btn-sm"
+          onClick={() => window.open(
+            `https://mail.google.com/mail/u/0/#all/${email.gmailMessageId}`,
+            '_blank', 'noopener,noreferrer'
+          )}
+        >Open in Gmail ↗</button>
+      </div>
+    </div>
+  );
+}
+
+// ── EmailListRow (row inside sender email list) ───────────────────────────────
+
+function EmailListRow({ email: initial, onRemove, onOpen }) {
+  const [email, setEmail] = useState(initial);
+  const [acting, setActing] = useState(false);
+
+  const act = (fn, patch) => async (e) => {
+    e.stopPropagation();
+    if (acting) return;
+    setActing(true);
+    try { await fn(email.id); setEmail((p) => ({ ...p, ...patch })); }
+    finally { setActing(false); }
+  };
+
+  const handleTrash = async (e) => {
+    e.stopPropagation();
+    if (acting) return;
+    setActing(true);
+    try { await EmailApi.trash(email.id); onRemove?.(email.id); }
+    finally { setActing(false); }
+  };
+
+  return (
+    <tr
+      className={`email-row${email.isUnread ? ' email-row--unread' : ''}${acting ? ' email-row--acting' : ''}`}
+      onClick={() => onOpen(email)}
+      title="View email"
+      style={{ cursor: 'pointer' }}
+    >
+      <td className="el-unread">{email.isUnread && <span className="unread-dot" />}</td>
+      <td className="el-subject">
+        <span className="el-subj-text">{email.subject || '(no subject)'}</span>
+        {email.snippet && <span className="el-snippet"> — {email.snippet}</span>}
+      </td>
+      <td className="el-meta">
+        {email.hasAttachments && <span className="el-attach" title="Has attachment">📎</span>}
+        {email.sizeEstimateBytes > 1048576 && <span className="el-size">{fmtSize(email.sizeEstimateBytes)}</span>}
+      </td>
+      <td className="el-date">{fmtDate(email.sentAtUtc)}</td>
+      <td className="el-actions" onClick={(e) => e.stopPropagation()}>
+        <button
+          className="action-btn"
+          title={email.isUnread ? 'Mark as read' : 'Mark as unread'}
+          onClick={email.isUnread
+            ? act(EmailApi.markRead,   { isUnread: false })
+            : act(EmailApi.markUnread, { isUnread: true  })}
+        >{email.isUnread ? '✓' : '●'}</button>
+        <button
+          className={`action-btn${email.isStarred ? ' action-btn--active' : ''}`}
+          title={email.isStarred ? 'Unstar' : 'Star'}
+          onClick={email.isStarred
+            ? act(EmailApi.unstar, { isStarred: false })
+            : act(EmailApi.star,   { isStarred: true  })}
+        >⭐</button>
+        <button
+          className="action-btn action-btn--danger"
+          title="Move to trash"
+          onClick={handleTrash}
+        >🗑️</button>
+      </td>
+    </tr>
+  );
+}
+
+// ── SenderEmails (right panel) ────────────────────────────────────────────────
+
+function SenderEmails({ sender }) {
+  const [emails, setEmails] = useState([]);
+  const [totalCount, setTotalCount] = useState(null);
+  const [page, setPage] = useState(1);
+  const [hasMore, setHasMore] = useState(true);
+  const [loading, setLoading] = useState(false);
+  const [openEmail, setOpenEmail] = useState(null);
+  const sentinelRef = useRef(null);
+
+  // Reset when sender changes
+  useEffect(() => {
+    setEmails([]);
+    setTotalCount(null);
+    setPage(1);
+    setHasMore(true);
+    setOpenEmail(null);
+  }, [sender.senderId]);
+
+  const fetchPage = useCallback((p) => {
+    setLoading(true);
+    SearchApi.query(`from:${sender.address}`, p, PAGE_SIZE)
+      .then((r) => {
+        setEmails((prev) => p === 1 ? r.items : [...prev, ...r.items]);
+        setTotalCount(r.totalCount);
+        setHasMore(p < r.totalPages);
+        setPage(p);
+      })
+      .finally(() => setLoading(false));
+  }, [sender]);
+
+  useEffect(() => { fetchPage(1); }, [fetchPage]);
+
+  // Infinite scroll sentinel
+  useEffect(() => {
+    const el = sentinelRef.current;
+    if (!el) return;
+    const obs = new IntersectionObserver(
+      (entries) => { if (entries[0].isIntersecting && hasMore && !loading) fetchPage(page + 1); },
+      { rootMargin: '200px' }
+    );
+    obs.observe(el);
+    return () => obs.disconnect();
+  }, [hasMore, loading, page, fetchPage]);
+
+  if (openEmail) {
+    return <EmailDetail email={openEmail} onBack={() => setOpenEmail(null)} />;
+  }
+
+  return (
+    <div className="sd-panel">
+      <div className="sd-panel-header">
+        <div className="sd-panel-name">{sender.displayName || sender.address}</div>
+        <div className="sd-panel-addr">{sender.displayName ? sender.address : ''}</div>
+        {totalCount !== null && (
+          <div className="sd-panel-count">{totalCount.toLocaleString()} email{totalCount !== 1 ? 's' : ''}</div>
+        )}
+      </div>
+
+      {emails.length > 0 && (
+        <table className="email-list">
+          <tbody>
+            {emails.map((e) => (
+              <EmailListRow
+                key={e.id}
+                email={e}
+                onOpen={setOpenEmail}
+                onRemove={(id) => setEmails((prev) => prev.filter((x) => x.id !== id))}
+              />
+            ))}
+          </tbody>
+        </table>
+      )}
+
+      <div ref={sentinelRef} />
+      {loading && <div className="fv-loading-more">Loading…</div>}
+      {!loading && !hasMore && emails.length > 0 && (
+        <div className="fv-end">— {emails.length.toLocaleString()} emails —</div>
+      )}
+      {!loading && emails.length === 0 && (
+        <div className="fv-empty">No emails found from this sender.</div>
+      )}
+    </div>
+  );
+}
+
+// ── Page ──────────────────────────────────────────────────────────────────────
+
+export default function Senders() {
+  const [senders, setSenders] = useState(null);
+  const [selected, setSelected] = useState(null);
+  const [search, setSearch] = useState('');
+
+  useEffect(() => {
+    AnalyticsApi.allSenders().then((list) => {
+      setSenders(list);
+      if (list.length > 0) setSelected(list[0]);
+    }).catch(() => setSenders([]));
+  }, []);
+
+  if (!senders) return <div className="page"><h2>Senders</h2><p className="muted">Loading…</p></div>;
+
+  if (senders.length === 0) return (
+    <div className="page">
+      <h2>Senders</h2>
+      <p className="muted">No senders yet — run a sync first.</p>
+    </div>
+  );
+
+  return (
+    <div className="senders-master-detail">
+      <SenderList
+        senders={senders}
+        selectedId={selected?.senderId}
+        onSelect={setSelected}
+        search={search}
+        onSearch={setSearch}
+      />
+      {selected && <SenderEmails key={selected.senderId} sender={selected} />}
     </div>
   );
 }
diff --git a/frontend/src/styles.css b/frontend/src/styles.css
index 8e52555..5bdbcc1 100644
--- a/frontend/src/styles.css
+++ b/frontend/src/styles.css
@@ -160,22 +160,85 @@ table.grid th, table.grid td { padding: 8px; border-bottom: 1px solid #2c3550; t
 }
 .react-grid-item.react-grid-placeholder { background: var(--accent); opacity: 0.25; border-radius: 10px; }
 
-/* Senders by volume */
-.senders-page { max-width: 1100px; }
-.tier { margin-top: 22px; }
-.tier-head { display: flex; align-items: center; gap: 10px; margin-bottom: 10px; }
-.tier-head h3 { margin: 0; font-size: 16px; }
-.tier-dot { width: 12px; height: 12px; border-radius: 50%; }
-.tier-count { color: var(--muted); font-size: 12px; }
-.sender-blocks { display: grid; grid-template-columns: repeat(auto-fill, minmax(190px, 1fr)); gap: 10px; }
-.sender-block { background: var(--panel); border: 1px solid #2c3550; border-top: 3px solid var(--accent); border-radius: 8px; padding: 10px 12px; }
-.sb-name { font-weight: 600; font-size: 13px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
-.sb-domain { color: var(--muted); font-size: 11px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; margin-bottom: 6px; }
-.sb-stats { display: flex; align-items: baseline; gap: 8px; flex-wrap: wrap; }
-.sb-count { font-size: 20px; font-weight: 700; }
-.sb-unread { font-size: 11px; color: var(--accent); }
-.sb-unsub { font-size: 10px; color: var(--muted); border: 1px solid #36405c; border-radius: 4px; padding: 0 4px; }
-.tier-more { margin-top: 8px; }
+/* ── Senders master-detail ─────────────────────────────────────────────── */
+.senders-master-detail {
+  display: grid;
+  grid-template-columns: 280px 1fr;
+  height: calc(100vh - 56px); /* fill below topbar */
+  overflow: hidden;
+}
+
+/* Left panel — sender list */
+.sl-panel {
+  display: flex;
+  flex-direction: column;
+  border-right: 1px solid #2c3550;
+  overflow: hidden;
+}
+.sl-search-wrap { padding: 10px 12px 6px; }
+.sl-search {
+  width: 100%;
+  box-sizing: border-box;
+  background: var(--panel-2);
+  border: 1px solid #2c3550;
+  color: var(--text);
+  border-radius: 6px;
+  padding: 7px 10px;
+  font-size: 13px;
+}
+.sl-count { padding: 0 14px 6px; font-size: 11px; color: var(--muted); }
+.sl-list { flex: 1; overflow-y: auto; margin: 0; padding: 0; list-style: none; }
+.sl-item {
+  display: block; width: 100%; text-align: left;
+  background: none; border: none; cursor: pointer;
+  padding: 10px 14px; border-bottom: 1px solid #1e2540;
+  color: var(--text);
+}
+.sl-item:hover { background: var(--panel-2); }
+.sl-item--active { background: var(--panel-2); border-left: 3px solid var(--accent); padding-left: 11px; }
+.sl-name { font-size: 13px; font-weight: 600; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+.sl-addr { font-size: 11px; color: var(--muted); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; margin-bottom: 3px; }
+.sl-meta { display: flex; align-items: baseline; gap: 8px; }
+.sl-email-count { font-size: 13px; font-weight: 700; color: var(--accent); }
+.sl-unread { font-size: 11px; color: var(--muted); }
+
+/* Right panel — email list for selected sender */
+.sd-panel {
+  display: flex;
+  flex-direction: column;
+  overflow-y: auto;
+  padding: 0;
+}
+.sd-panel-header {
+  padding: 16px 20px 12px;
+  border-bottom: 1px solid #2c3550;
+  background: var(--panel);
+  position: sticky; top: 0; z-index: 1;
+}
+.sd-panel-name { font-size: 16px; font-weight: 700; }
+.sd-panel-addr { font-size: 12px; color: var(--muted); margin-bottom: 4px; }
+.sd-panel-count { font-size: 12px; color: var(--muted); }
+
+/* Single email detail view */
+.sd-detail { padding: 20px; max-width: 760px; }
+.sd-back {
+  display: inline-flex; align-items: center; gap: 4px;
+  background: none; border: 1px solid #2c3550; border-radius: 6px;
+  color: var(--text); font-size: 13px; cursor: pointer;
+  padding: 5px 12px; margin-bottom: 18px;
+}
+.sd-back:hover { background: var(--panel-2); }
+.sd-detail-header { margin-bottom: 14px; }
+.sd-detail-subject { font-size: 18px; font-weight: 700; margin-bottom: 6px; }
+.sd-detail-meta { font-size: 12px; color: var(--muted); display: flex; flex-wrap: wrap; gap: 4px; align-items: center; }
+.sd-detail-sep { opacity: 0.4; }
+.sd-snippet { background: var(--panel); border: 1px solid #2c3550; border-radius: 8px; padding: 14px 16px; font-size: 13px; line-height: 1.6; color: var(--muted); white-space: pre-wrap; margin-bottom: 18px; }
+.sd-detail-actions { display: flex; gap: 10px; }
+.btn-sm {
+  background: var(--accent); color: #fff; border: none; border-radius: 6px;
+  padding: 7px 14px; font-size: 13px; cursor: pointer; font-weight: 600;
+}
+.btn-sm:hover { opacity: 0.85; }
 
 .page { max-width: 900px; }
 .form-row { display: flex; gap: 10px; margin: 14px 0; }