diff --git a/src/viewer/index.html b/src/viewer/index.html
index 551d016..9751807 100644
--- a/src/viewer/index.html
+++ b/src/viewer/index.html
@@ -1005,7 +1005,7 @@ <h1>agentmemory</h1>
 
     var state = {
       activeTab: 'dashboard',
-      dashboard: { loaded: false, health: null, sessions: [], memories: [], graphStats: null, recentAudit: [], lessons: [], crystals: [] },
+      dashboard: { loaded: false, health: null, sessions: [], memories: [], graphStats: null, recentAudit: [], lessons: [], crystals: [], semantic: [], procedural: [], relations: [] },
       graph: { loaded: false, nodes: [], edges: [], stats: null, filters: {}, selectedNode: null },
       memories: { loaded: false, items: [], search: '', typeFilter: '' },
       timeline: { loaded: false, observations: [], sessionId: '', minImportance: 0, page: 0, pageSize: 50 },
@@ -1039,6 +1039,18 @@ <h1>agentmemory</h1>
       if (!s) return '';
       return s.length > n ? s.slice(0, n) + '...' : s;
     }
+    function asArray(value) {
+      return Array.isArray(value) ? value : [];
+    }
+    function firstArray() {
+      for (var i = 0; i < arguments.length; i++) {
+        if (Array.isArray(arguments[i])) return arguments[i];
+      }
+      return [];
+    }
+    function asString(value) {
+      return value === undefined || value === null ? '' : String(value);
+    }
     function debounce(fn, ms) {
       var t;
       return function() {
@@ -1128,15 +1140,15 @@ <h1>agentmemory</h1>
           apiGet('crystals')
         ]);
         state.dashboard.health = results[0];
-        state.dashboard.sessions = (results[1] && results[1].sessions) || [];
-        state.dashboard.memories = (results[2] && results[2].memories) || [];
+        state.dashboard.sessions = asArray(results[1] && results[1].sessions);
+        state.dashboard.memories = asArray(results[2] && results[2].memories);
         state.dashboard.graphStats = results[3];
-        state.dashboard.recentAudit = (results[4] && results[4].entries) || [];
-        state.dashboard.semantic = (results[5] && results[5].facts) || (results[5] && results[5].semantic) || [];
-        state.dashboard.procedural = (results[6] && results[6].procedures) || (results[6] && results[6].procedural) || [];
-        state.dashboard.lessons = (results[8] && results[8].lessons) || [];
-        state.dashboard.crystals = (results[9] && results[9].crystals) || [];
-        state.dashboard.relations = (results[7] && results[7].relations) || [];
+        state.dashboard.recentAudit = asArray(results[4] && results[4].entries);
+        state.dashboard.semantic = firstArray(results[5] && results[5].facts, results[5] && results[5].semantic);
+        state.dashboard.procedural = firstArray(results[6] && results[6].procedures, results[6] && results[6].procedural);
+        state.dashboard.lessons = asArray(results[8] && results[8].lessons);
+        state.dashboard.crystals = asArray(results[9] && results[9].crystals);
+        state.dashboard.relations = asArray(results[7] && results[7].relations);
         state.dashboard.loaded = true;
         renderDashboard();
       } catch (err) {
@@ -1167,17 +1179,20 @@ <h1>agentmemory</h1>
       var snap = h.health || {};
       var healthStatus = h.status || 'unknown';
       var dotClass = healthStatus === 'healthy' ? 'healthy' : healthStatus === 'degraded' ? 'degraded' : healthStatus === 'critical' ? 'critical' : '';
-      var activeSessions = d.sessions.filter(function(s) { return s.status === 'active'; }).length;
+      var sessions = asArray(d.sessions).filter(function(s) { return s && typeof s === 'object'; });
+      var memories = asArray(d.memories).filter(function(m) { return m && typeof m === 'object'; });
+      var recentAudit = asArray(d.recentAudit).filter(function(a) { return a && typeof a === 'object'; });
+      var activeSessions = sessions.filter(function(s) { return s.status === 'active'; }).length;
       var gs = d.graphStats || {};
       var nodeCount = gs.totalNodes !== undefined ? gs.totalNodes : (gs.nodes !== undefined ? gs.nodes : (gs.nodeCount || 0));
       var edgeCount = gs.totalEdges !== undefined ? gs.totalEdges : (gs.edges !== undefined ? gs.edges : (gs.edgeCount || 0));
-      var fMetrics = h.functionMetrics || [];
+      var fMetrics = asArray(h.functionMetrics).filter(function(m) { return m && typeof m === 'object'; });
       var cb = h.circuitBreaker || null;
-      var workers = snap.workers || [];
+      var workers = asArray(snap.workers).filter(function(w) { return w && typeof w === 'object'; });
 
       var html = '';
       // First-run hero: empty dashboard = guided next step
-      if (d.sessions.length === 0) {
+      if (sessions.length === 0) {
         html += '<div class="card" style="margin-bottom:14px;padding:24px 28px;background:var(--bg-subtle);border-left:3px solid var(--accent);">' +
           '<div style="font-family:var(--font-ui);font-size:11px;letter-spacing:0.15em;text-transform:uppercase;color:var(--accent);font-weight:700;margin-bottom:8px;">First run &rarr; magical moment in 10 seconds</div>' +
           '<div style="font-family:var(--font-display,Lora,Georgia,serif);font-size:22px;font-weight:700;color:var(--ink);margin-bottom:8px;">Seed sample data + prove semantic recall works</div>' +
@@ -1187,10 +1202,10 @@ <h1>agentmemory</h1>
           '</div>';
       }
       html += '<div class="stats-grid">';
-      html += '<div class="stat-card"><div class="label">Sessions</div><div class="value">' + d.sessions.length + '</div><div class="sub">' + activeSessions + ' active</div></div>';
-      html += '<div class="stat-card"><div class="label">Memories</div><div class="value">' + d.memories.length + '</div><div class="sub">latest versions</div></div>';
-      var lessonCount = (d.lessons || []).length;
-      var crystalCount = (d.crystals || []).length;
+      html += '<div class="stat-card"><div class="label">Sessions</div><div class="value">' + sessions.length + '</div><div class="sub">' + activeSessions + ' active</div></div>';
+      html += '<div class="stat-card"><div class="label">Memories</div><div class="value">' + memories.length + '</div><div class="sub">latest versions</div></div>';
+      var lessonCount = asArray(d.lessons).length;
+      var crystalCount = asArray(d.crystals).length;
       html += '<div class="stat-card"><div class="label">Lessons</div><div class="value">' + lessonCount + '</div><div class="sub">confidence-scored</div></div>';
       html += '<div class="stat-card"><div class="label">Crystals</div><div class="value">' + crystalCount + '</div><div class="sub">action digests</div></div>';
       html += '<div class="stat-card"><div class="label">Graph Nodes</div><div class="value">' + nodeCount + '</div><div class="sub">' + edgeCount + ' edges</div></div>';
@@ -1203,10 +1218,10 @@ <h1>agentmemory</h1>
         html += '<div class="stat-card"><div class="label">Circuit Breaker</div><div class="value"><span class="cb-indicator ' + cbClass + '">' + esc(cb.state) + '</span></div>';
         html += '<div class="sub">' + (cb.failures || 0) + ' failures</div></div>';
       }
-      var totalObs = d.sessions.reduce(function(a, s) { return a + (s.observationCount || 0); }, 0);
+      var totalObs = sessions.reduce(function(a, s) { return a + (s.observationCount || 0); }, 0);
       var tokenBudget = parseInt(new URLSearchParams(window.location.search).get('tokenBudget') || '2000', 10) || 2000;
       var estFull = totalObs * 80;
-      var estInjected = d.sessions.length * tokenBudget;
+      var estInjected = sessions.length * tokenBudget;
       var savings = estFull > 0 ? Math.round((1 - estInjected / Math.max(estFull, 1)) * 100) : 0;
       if (savings < 0) savings = 0;
       var tokensSaved = Math.max(0, estFull - estInjected);
@@ -1252,17 +1267,19 @@ <h1>agentmemory</h1>
         html += '</div>';
       }
 
-      if (snap.alerts && snap.alerts.length > 0) {
-        html += '<div class="card" style="margin-bottom:16px;border-color:var(--accent);border-width:2px;"><div class="card-title" style="color:var(--accent);border-bottom-color:var(--accent);">Alerts (' + snap.alerts.length + ')</div>';
-        snap.alerts.forEach(function(al) {
+      var alerts = asArray(snap.alerts);
+      if (alerts.length > 0) {
+        html += '<div class="card" style="margin-bottom:16px;border-color:var(--accent);border-width:2px;"><div class="card-title" style="color:var(--accent);border-bottom-color:var(--accent);">Alerts (' + alerts.length + ')</div>';
+        alerts.forEach(function(al) {
           html += '<div style="font-size:12px;color:var(--accent);padding:4px 0;border-bottom:1px solid var(--border-light);font-family:var(--font-ui);">' + esc(al) + '</div>';
         });
         html += '</div>';
       }
 
-      if (snap.notes && snap.notes.length > 0) {
-        html += '<div class="card" style="margin-bottom:16px;"><div class="card-title" style="color:var(--ink-muted);">Notes (' + snap.notes.length + ')</div>';
-        snap.notes.forEach(function(n) {
+      var notes = asArray(snap.notes);
+      if (notes.length > 0) {
+        html += '<div class="card" style="margin-bottom:16px;"><div class="card-title" style="color:var(--ink-muted);">Notes (' + notes.length + ')</div>';
+        notes.forEach(function(n) {
           html += '<div style="font-size:12px;color:var(--ink-muted);padding:4px 0;border-bottom:1px solid var(--border-light);font-family:var(--font-ui);">' + esc(n) + '</div>';
         });
         html += '</div>';
@@ -1271,14 +1288,16 @@ <h1>agentmemory</h1>
       html += '<div class="two-col">';
 
       html += '<div class="card"><div class="card-title">Recent Sessions</div>';
-      if (d.sessions.length === 0) {
+      if (sessions.length === 0) {
         html += '<div class="empty-state"><p>No sessions yet. Start a coding session with agentmemory hooks enabled.</p></div>';
       } else {
-        var recent = d.sessions.slice().sort(function(a, b) { return (b.startedAt || '').localeCompare(a.startedAt || ''); }).slice(0, 5);
+        var recent = sessions.slice().sort(function(a, b) { return (b.startedAt || '').localeCompare(a.startedAt || ''); }).slice(0, 5);
         html += '<table><tr><th>Project</th><th>Status</th><th>Obs</th><th>Started</th></tr>';
         recent.forEach(function(s) {
           var statusBadge = s.status === 'active' ? 'badge-green' : s.status === 'completed' ? 'badge-blue' : 'badge-muted';
-          html += '<tr><td style="color:var(--ink);font-weight:500;">' + esc(s.project ? s.project.split('/').pop() : s.id.slice(0,8)) + '</td>';
+          var sessionId = asString(s.id || s.sessionId);
+          var projectLabel = s.project ? asString(s.project).split('/').pop() : truncate(sessionId, 8);
+          html += '<tr><td style="color:var(--ink);font-weight:500;">' + esc(projectLabel || 'unknown') + '</td>';
           html += '<td><span class="badge ' + statusBadge + '">' + esc(s.status) + '</span></td>';
           html += '<td style="color:var(--ink-muted);font-family:var(--font-mono);font-size:12px;">' + (s.observationCount || 0) + '</td>';
           html += '<td style="font-family:var(--font-mono);font-size:11px;color:var(--ink-faint);">' + esc(shortTime(s.startedAt)) + '</td></tr>';
@@ -1288,10 +1307,10 @@ <h1>agentmemory</h1>
       html += '</div>';
 
       html += '<div class="card"><div class="card-title">Recent Activity</div>';
-      if (d.recentAudit.length === 0) {
+      if (recentAudit.length === 0) {
         html += '<div class="empty-state"><p>No activity recorded yet</p></div>';
       } else {
-        d.recentAudit.forEach(function(a) {
+        recentAudit.forEach(function(a) {
           var badgeClass = OP_BADGES[a.operation] || 'badge-muted';
           html += '<div style="padding:6px 0;border-bottom:1px solid var(--border-light);font-size:13px;">';
           html += '<span class="badge ' + badgeClass + '">' + esc(a.operation) + '</span> ';
@@ -1346,9 +1365,9 @@ <h1>agentmemory</h1>
         html += '</div>';
       }
 
-      var semFacts = d.semantic || [];
-      var procItems = d.procedural || [];
-      var relItems = d.relations || [];
+      var semFacts = asArray(d.semantic).filter(function(f) { return f && typeof f === 'object'; });
+      var procItems = asArray(d.procedural).filter(function(p) { return p && typeof p === 'object'; });
+      var relItems = asArray(d.relations).filter(function(r) { return r && typeof r === 'object'; });
 
       html += '<hr class="section-rule">';
       html += '<div class="two-col">';
@@ -1380,10 +1399,11 @@ <h1>agentmemory</h1>
             html += '<div style="font-weight:600;color:var(--ink);font-family:var(--font-display);font-size:13px;">' + esc(p.name || p.title || 'Procedure') + '</div>';
             if (p.trigger || p.triggerCondition) html += '<div style="font-size:11px;color:var(--ink-faint);font-family:var(--font-mono);margin-top:2px;">Trigger: ' + esc(p.trigger || p.triggerCondition) + '</div>';
             if (p.frequency) html += '<div style="font-size:11px;color:var(--ink-faint);margin-top:2px;">Freq: ' + p.frequency + '</div>';
-            if (p.steps && p.steps.length > 0) {
+            var steps = asArray(p.steps);
+            if (steps.length > 0) {
               html += '<ol class="procedure-steps">';
-              p.steps.slice(0, 4).forEach(function(s) { html += '<li>' + esc(typeof s === 'string' ? s : s.description || s.action || JSON.stringify(s)) + '</li>'; });
-              if (p.steps.length > 4) html += '<li style="color:var(--ink-faint);font-style:italic;">+ ' + (p.steps.length - 4) + ' more...</li>';
+              steps.slice(0, 4).forEach(function(s) { html += '<li>' + esc(typeof s === 'string' ? s : s.description || s.action || JSON.stringify(s)) + '</li>'; });
+              if (steps.length > 4) html += '<li style="color:var(--ink-faint);font-style:italic;">+ ' + (steps.length - 4) + ' more...</li>';
               html += '</ol>';
             }
             html += '</div>';
diff --git a/test/viewer-dashboard.test.ts b/test/viewer-dashboard.test.ts
new file mode 100644
index 0000000..deabcf8
--- /dev/null
+++ b/test/viewer-dashboard.test.ts
@@ -0,0 +1,168 @@
+import { readFileSync } from "node:fs";
+import { runInNewContext } from "node:vm";
+import { describe, expect, it, vi } from "vitest";
+
+type ViewerElement = {
+  innerHTML: string;
+  textContent: string;
+  value: string;
+  dataset: Record<string, string>;
+  classList: {
+    toggle: ReturnType<typeof vi.fn>;
+    add: ReturnType<typeof vi.fn>;
+    remove: ReturnType<typeof vi.fn>;
+  };
+  addEventListener: ReturnType<typeof vi.fn>;
+  removeEventListener: ReturnType<typeof vi.fn>;
+  querySelector: ReturnType<typeof vi.fn>;
+  querySelectorAll: ReturnType<typeof vi.fn>;
+};
+
+function escapeHtml(value: string): string {
+  return value
+    .replaceAll("&", "&amp;")
+    .replaceAll("<", "&lt;")
+    .replaceAll(">", "&gt;")
+    .replaceAll('"', "&quot;");
+}
+
+function loadViewerScript(): string {
+  const html = readFileSync(
+    new URL("../src/viewer/index.html", import.meta.url),
+    "utf8",
+  );
+  const match = html.match(
+    /<script nonce="__AGENTMEMORY_VIEWER_NONCE__">([\s\S]*?)<\/script>/,
+  );
+  if (!match) throw new Error("viewer script not found");
+
+  return match[1].replace(
+    /\s+loadTab\('dashboard'\);\s+connectWs\(\);\s+startDashboardAutoRefresh\(\);\s*$/,
+    "\n",
+  );
+}
+
+function createViewerSandbox() {
+  const elements = new Map<string, ViewerElement>();
+  const getElement = (id: string) => {
+    if (!elements.has(id)) {
+      elements.set(id, {
+        innerHTML: "",
+        textContent: "",
+        value: "",
+        dataset: {},
+        classList: { toggle: vi.fn(), add: vi.fn(), remove: vi.fn() },
+        addEventListener: vi.fn(),
+        removeEventListener: vi.fn(),
+        querySelector: vi.fn(() => null),
+        querySelectorAll: vi.fn(() => []),
+      });
+    }
+    return elements.get(id);
+  };
+
+  const sandbox: Record<string, unknown> = {
+    console: { log: vi.fn(), warn: vi.fn(), error: vi.fn() },
+    URLSearchParams,
+    Date,
+    JSON,
+    Math,
+    Number,
+    Object,
+    Promise,
+    String,
+    Array,
+    parseInt,
+    setTimeout,
+    clearTimeout,
+    setInterval: vi.fn(() => 0),
+    clearInterval: vi.fn(),
+    fetch: vi.fn(),
+    alert: vi.fn(),
+    localStorage: { getItem: vi.fn(() => null), setItem: vi.fn() },
+    WebSocket: vi.fn(),
+    document: {
+      documentElement: { dataset: {} },
+      addEventListener: vi.fn(),
+      querySelectorAll: vi.fn(() => []),
+      getElementById: vi.fn(getElement),
+      createElement: vi.fn(() => {
+        const node: { innerHTML: string; value: string; textContent?: string } = {
+          innerHTML: "",
+          value: "",
+        };
+        Object.defineProperty(node, "textContent", {
+          get: () => node.value,
+          set(value: unknown) {
+            node.value = String(value);
+            node.innerHTML = escapeHtml(String(value));
+          },
+        });
+        return node;
+      }),
+    },
+  };
+
+  sandbox.window = sandbox;
+  sandbox.location = {
+    search: "",
+    protocol: "http:",
+    hostname: "localhost",
+    port: "3113",
+    host: "localhost:3113",
+    origin: "http://localhost:3113",
+  };
+  sandbox.matchMedia = vi.fn(() => ({ matches: false }));
+
+  return { sandbox, elements };
+}
+
+describe("viewer dashboard", () => {
+  it("renders partial dashboard payloads without crashing", () => {
+    const { sandbox, elements } = createViewerSandbox();
+    runInNewContext(loadViewerScript(), sandbox, { filename: "viewer.html" });
+
+    const state = sandbox.state as { dashboard: unknown };
+    state.dashboard = {
+      loaded: true,
+      health: {
+        status: "healthy",
+        health: {
+          connectionState: "connected",
+          alerts: { malformed: true },
+          notes: "not-an-array",
+        },
+        functionMetrics: undefined,
+      },
+      sessions: [
+        {
+          status: "completed",
+          observationCount: 2,
+          startedAt: "2026-05-14T03:00:00.000Z",
+        },
+        null,
+        {
+          id: "ses_good",
+          project: "C:/work/app",
+          status: "active",
+          observationCount: 1,
+          startedAt: "2026-05-14T04:00:00.000Z",
+        },
+      ],
+      memories: { malformed: true },
+      graphStats: { nodes: 1, edges: 0 },
+      recentAudit: undefined,
+      lessons: undefined,
+      crystals: undefined,
+      semantic: { malformed: true },
+      procedural: [{ title: "Recovered procedure", steps: undefined }],
+      relations: [{ type: "related" }],
+    };
+
+    expect(() => (sandbox.renderDashboard as () => void)()).not.toThrow();
+    const dashboard = elements.get("view-dashboard");
+    expect(dashboard?.innerHTML).toContain("Recent Sessions");
+    expect(dashboard?.innerHTML).toContain("unknown");
+    expect(dashboard?.innerHTML).toContain("Recovered procedure");
+  });
+});