diff --git a/README.md b/README.md
index ec26e75..1d374ad 100644
--- a/README.md
+++ b/README.md
@@ -27,11 +27,6 @@ npm run lint
 ```
 
 ## Current scope
-- Minimal frontend shell only.
-- No live API wiring in the baseline commit.
-- `environment summary` stays mock-only until a worker-visible route exists in the current backend runtime.
-
-## Next development slice
-1. Add app shell sections for `timeline`, `audit feed`, and `environment summary`.
-2. Introduce typed DTO/fixture layer from the approved first-slice contracts.
-3. Keep `environment summary` behind mock data until the live route is available.
+- App shell slice for `timeline`, `audit feed`, and `environment summary`.
+- Local typed fixtures only. No live API wiring.
+- `environment summary` stays explicitly mock-only until a worker-visible route exists in the current backend runtime.
diff --git a/src/App.css b/src/App.css
index 6f16b54..b7c82f0 100644
--- a/src/App.css
+++ b/src/App.css
@@ -1,7 +1,7 @@
 :root {
-  color: #e5eef7;
-  background: #0b1220;
-  font-family: Inter, system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
+  color: #ebf1ea;
+  background: #101611;
+  font-family: 'IBM Plex Sans', 'Segoe UI', sans-serif;
 }
 
 body {
@@ -9,8 +9,9 @@ body {
   min-width: 320px;
   min-height: 100vh;
   background:
-    radial-gradient(circle at top, rgba(56, 189, 248, 0.18), transparent 35%),
-    linear-gradient(180deg, #020617 0%, #0f172a 100%);
+    radial-gradient(circle at top left, rgba(201, 255, 148, 0.14), transparent 32%),
+    radial-gradient(circle at right, rgba(102, 163, 255, 0.1), transparent 28%),
+    linear-gradient(180deg, #0b100c 0%, #161d17 100%);
 }
 
 #root {
@@ -18,23 +19,38 @@ body {
 }
 
 .app-shell {
-  max-width: 1120px;
+  max-width: 1180px;
   margin: 0 auto;
-  padding: 48px 24px 64px;
+  padding: 40px 20px 56px;
 }
 
 .hero-card,
-.next-slice-card,
-.status-grid article {
-  background: rgba(15, 23, 42, 0.8);
-  border: 1px solid rgba(148, 163, 184, 0.18);
-  border-radius: 24px;
-  box-shadow: 0 20px 45px rgba(2, 6, 23, 0.35);
+.overview-strip article,
+.panel,
+.summary-card,
+.timeline-item,
+.audit-item {
+  background: rgba(18, 25, 20, 0.84);
+  border: 1px solid rgba(207, 234, 212, 0.1);
+  box-shadow: 0 18px 40px rgba(5, 8, 6, 0.3);
 }
 
 .hero-card,
-.next-slice-card {
+.panel,
+.overview-strip article,
+.summary-card,
+.timeline-item,
+.audit-item {
+  border-radius: 22px;
+}
+
+.hero-card {
+  display: grid;
+  grid-template-columns: minmax(0, 1.1fr) minmax(280px, 0.9fr);
+  gap: 24px;
+  align-items: end;
   padding: 28px;
+  margin-bottom: 20px;
 }
 
 .eyebrow {
@@ -42,52 +58,177 @@ body {
   text-transform: uppercase;
   letter-spacing: 0.12em;
   font-size: 0.8rem;
-  color: #38bdf8;
+  color: #b8f36b;
 }
 
 h1,
 h2,
-p,
-ul {
+h3,
+p {
   margin-top: 0;
 }
 
 h1 {
-  font-size: clamp(2.4rem, 5vw, 4rem);
-  margin-bottom: 16px;
+  font-size: clamp(2.4rem, 4vw, 3.5rem);
+  margin-bottom: 0;
+  line-height: 0.95;
+  letter-spacing: -0.04em;
+}
+
+h2 {
+  margin-bottom: 0;
+  font-size: 1.2rem;
+}
+
+h3 {
+  margin-bottom: 8px;
+  font-size: 1rem;
 }
 
 .lede {
-  font-size: 1.1rem;
+  margin-bottom: 0;
+  align-self: stretch;
+  font-size: 1rem;
   line-height: 1.7;
-  max-width: 68ch;
-  color: #cbd5e1;
+  color: #c8d4c8;
 }
 
-.status-grid {
+.overview-strip {
   display: grid;
   grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
-  gap: 20px;
-  margin: 28px 0;
+  gap: 16px;
+  margin-bottom: 20px;
 }
 
-.status-grid article {
+.overview-strip article {
+  padding: 18px 20px;
+}
+
+.kicker,
+.section-label,
+.item-meta {
+  display: inline-block;
+  margin: 0 0 8px;
+  font-size: 0.75rem;
+  text-transform: uppercase;
+  letter-spacing: 0.1em;
+  color: #93a393;
+}
+
+.overview-strip strong {
+  display: block;
+  font-size: 1rem;
+  color: #f5f8f4;
+}
+
+.content-grid {
+  display: grid;
+  grid-template-columns: repeat(12, minmax(0, 1fr));
+  gap: 20px;
+}
+
+.panel {
+  grid-column: span 4;
   padding: 22px;
 }
 
-.status-grid h2,
-.next-slice-card h2 {
-  margin-bottom: 12px;
-  font-size: 1.1rem;
+.panel-wide {
+  grid-column: span 8;
 }
 
-.status-grid p,
-.next-slice-card li {
-  color: #cbd5e1;
-  line-height: 1.6;
+.panel-heading {
+  display: flex;
+  align-items: flex-start;
+  justify-content: space-between;
+  gap: 16px;
+  margin-bottom: 18px;
 }
 
-.next-slice-card ul {
-  padding-left: 20px;
+.panel-badge {
+  border-radius: 999px;
+  padding: 7px 12px;
+  font-size: 0.8rem;
+  color: #d8f4af;
+  background: rgba(184, 243, 107, 0.12);
+  border: 1px solid rgba(184, 243, 107, 0.18);
+}
+
+.panel-badge.muted {
+  color: #c6d0c6;
+  background: rgba(198, 208, 198, 0.08);
+  border-color: rgba(198, 208, 198, 0.12);
+}
+
+.timeline-list,
+.audit-list,
+.summary-grid {
+  display: grid;
+  gap: 14px;
+}
+
+.timeline-list {
+  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
+}
+
+.timeline-item,
+.audit-item,
+.summary-card {
+  padding: 18px;
+}
+
+.timeline-item h3,
+.audit-item h3,
+.summary-card h3 {
+  color: #f5f8f4;
+}
+
+.timeline-item p,
+.audit-item p,
+.summary-card p {
   margin-bottom: 0;
+  line-height: 1.55;
+  color: #c8d4c8;
+}
+
+.timeline-stable {
+  border-color: rgba(157, 255, 172, 0.16);
+}
+
+.timeline-active {
+  border-color: rgba(255, 211, 122, 0.18);
+}
+
+.timeline-attention {
+  border-color: rgba(255, 143, 143, 0.18);
+}
+
+.audit-target {
+  color: #b8f36b;
+}
+
+.summary-grid {
+  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
+}
+
+@media (max-width: 900px) {
+  .hero-card,
+  .content-grid {
+    grid-template-columns: 1fr;
+  }
+
+  .panel,
+  .panel-wide {
+    grid-column: auto;
+  }
+}
+
+@media (max-width: 640px) {
+  .app-shell {
+    padding-inline: 16px;
+  }
+
+  .hero-card,
+  .panel {
+    padding: 20px;
+  }
 }
diff --git a/src/App.tsx b/src/App.tsx
index 1458746..2d2e82d 100644
--- a/src/App.tsx
+++ b/src/App.tsx
@@ -1,45 +1,101 @@
 import './App.css'
-
-const nextSlice = [
-  'Timeline block wired to approved DTO fixtures',
-  'Audit feed block wired to approved DTO fixtures',
-  'Environment summary placeholder kept mock-only',
-]
+import {
+  auditEntries,
+  environmentSummaryItems,
+  timelineEntries,
+} from './fixtures/dashboard'
 
 function App() {
   return (
     <main className="app-shell">
-      <section className="hero-card">
-        <p className="eyebrow">Mission Control / devopspanel</p>
-        <h1>DevOps orchestration admin panel</h1>
+      <header className="hero-card">
+        <div>
+          <p className="eyebrow">Mission Control / devopspanel</p>
+          <h1>Operations shell</h1>
+        </div>
         <p className="lede">
-          Baseline frontend scaffold for the first implementation slice. This commit
-          intentionally sets the stack and shell contract before live integrations.
+          Local mock slice for shell structure only. Timeline, audit feed, and
+          environment summary are rendered from typed fixtures with no live API wiring.
         </p>
-      </section>
+      </header>
 
-      <section className="status-grid">
+      <section className="overview-strip" aria-label="App slice overview">
         <article>
-          <h2>Baseline stack</h2>
-          <p>React + TypeScript + Vite</p>
+          <span className="kicker">Stack</span>
+          <strong>React + TypeScript + Vite</strong>
         </article>
         <article>
-          <h2>Current state</h2>
-          <p>Scaffold only, no runtime data wiring yet</p>
+          <span className="kicker">Data mode</span>
+          <strong>Local typed fixtures</strong>
         </article>
         <article>
-          <h2>Guardrail</h2>
-          <p>Environment summary remains mock-only until live worker-visible route exists</p>
+          <span className="kicker">Guardrail</span>
+          <strong>Environment summary is mock-only</strong>
         </article>
       </section>
 
-      <section className="next-slice-card">
-        <h2>Next development slice</h2>
-        <ul>
-          {nextSlice.map((item) => (
-            <li key={item}>{item}</li>
-          ))}
-        </ul>
+      <section className="content-grid">
+        <article className="panel panel-wide">
+          <div className="panel-heading">
+            <div>
+              <p className="section-label">Timeline</p>
+              <h2>Planned operator moments</h2>
+            </div>
+            <span className="panel-badge">{timelineEntries.length} items</span>
+          </div>
+
+          <div className="timeline-list">
+            {timelineEntries.map((entry) => (
+              <div key={entry.id} className={`timeline-item timeline-${entry.tone}`}>
+                <p className="item-meta">{entry.windowLabel}</p>
+                <h3>{entry.title}</h3>
+                <p>{entry.detail}</p>
+              </div>
+            ))}
+          </div>
+        </article>
+
+        <article className="panel">
+          <div className="panel-heading">
+            <div>
+              <p className="section-label">Audit Feed</p>
+              <h2>Recent shell events</h2>
+            </div>
+          </div>
+
+          <div className="audit-list">
+            {auditEntries.map((entry) => (
+              <div key={entry.id} className="audit-item">
+                <p className="item-meta">{entry.occurredAt}</p>
+                <h3>
+                  {entry.actor} {entry.action}
+                </h3>
+                <p className="audit-target">{entry.target}</p>
+                <p>{entry.summary}</p>
+              </div>
+            ))}
+          </div>
+        </article>
+
+        <article className="panel panel-wide">
+          <div className="panel-heading">
+            <div>
+              <p className="section-label">Environment Summary</p>
+              <h2>Mock-only environment snapshot</h2>
+            </div>
+            <span className="panel-badge muted">mock only</span>
+          </div>
+
+          <div className="summary-grid">
+            {environmentSummaryItems.map((item) => (
+              <div key={item.id} className="summary-card">
+                <p className="item-meta">{item.label}</p>
+                <h3>{item.value}</h3>
+                <p>{item.note}</p>
+              </div>
+            ))}
+          </div>
+        </article>
       </section>
     </main>
   )
diff --git a/src/fixtures/dashboard.ts b/src/fixtures/dashboard.ts
new file mode 100644
index 0000000..c6fa143
--- /dev/null
+++ b/src/fixtures/dashboard.ts
@@ -0,0 +1,77 @@
+import type {
+  AuditEntry,
+  EnvironmentSummaryItem,
+  TimelineEntry,
+} from '../types/dashboard'
+
+export const timelineEntries: TimelineEntry[] = [
+  {
+    id: 'tl-1',
+    title: 'Morning maintenance window',
+    windowLabel: '08:30-09:00 UTC',
+    detail: 'Patch validation and worker drift review staged for operator sign-off.',
+    tone: 'stable',
+  },
+  {
+    id: 'tl-2',
+    title: 'Release rehearsal',
+    windowLabel: '11:15-12:00 UTC',
+    detail: 'Dry-run checklist for deployment sequencing and rollback notes.',
+    tone: 'active',
+  },
+  {
+    id: 'tl-3',
+    title: 'Credential rotation follow-up',
+    windowLabel: '15:00-15:30 UTC',
+    detail: 'Pending verification items remain isolated to the mock shell.',
+    tone: 'attention',
+  },
+]
+
+export const auditEntries: AuditEntry[] = [
+  {
+    id: 'af-1',
+    actor: 'ops.release',
+    action: 'approved',
+    target: 'frontend-shell-slice',
+    occurredAt: '10:42 UTC',
+    summary: 'Scope held to local fixtures and presentational shell changes only.',
+  },
+  {
+    id: 'af-2',
+    actor: 'runtime.guardrail',
+    action: 'flagged',
+    target: 'environment-summary',
+    occurredAt: '09:18 UTC',
+    summary: 'Section copy must stay explicitly mock-only until backend visibility exists.',
+  },
+  {
+    id: 'af-3',
+    actor: 'design.review',
+    action: 'recorded',
+    target: 'layout-baseline',
+    occurredAt: '08:05 UTC',
+    summary: 'Three-panel shell accepted as the next UI slice for iteration.',
+  },
+]
+
+export const environmentSummaryItems: EnvironmentSummaryItem[] = [
+  {
+    id: 'env-1',
+    label: 'Mock worker coverage',
+    value: '12 workers',
+    note: 'Mock dataset only. Not sourced from runtime inventory.',
+  },
+  {
+    id: 'env-2',
+    label: 'Mock alert posture',
+    value: '2 advisory notices',
+    note: 'Mock status text for layout validation only.',
+  },
+  {
+    id: 'env-3',
+    label: 'Mock change queue',
+    value: '5 queued actions',
+    note: 'Mock placeholder until live API contracts are introduced.',
+  },
+]
diff --git a/src/types/dashboard.ts b/src/types/dashboard.ts
new file mode 100644
index 0000000..29dfb27
--- /dev/null
+++ b/src/types/dashboard.ts
@@ -0,0 +1,25 @@
+export type TimelineTone = 'stable' | 'active' | 'attention'
+
+export interface TimelineEntry {
+  id: string
+  title: string
+  windowLabel: string
+  detail: string
+  tone: TimelineTone
+}
+
+export interface AuditEntry {
+  id: string
+  actor: string
+  action: string
+  target: string
+  occurredAt: string
+  summary: string
+}
+
+export interface EnvironmentSummaryItem {
+  id: string
+  label: string
+  value: string
+  note: string
+}