diff --git a/src/App.jsx b/src/App.jsx
index 45da7e0..169eb51 100644
--- a/src/App.jsx
+++ b/src/App.jsx
@@ -2,18 +2,21 @@ import { useState, useEffect } from 'react'
 import { generateToken, loadState, saveState } from './api.js'
 import { createState } from './gameState.js'
 import { BACKGROUNDS } from './constants.js'
-import Ledger from './screens/Ledger.jsx'
+import Shell from './components/Shell.jsx'
+import Actor from './screens/Actor.jsx'
+import Forum from './screens/Forum.jsx'
 import Map from './screens/Map.jsx'
-import Prologue from './screens/Prologue.jsx'
 import './App.css'
 
+import contextsJson from './config/contexts.json'
+
 const TOKEN_KEY = 'otivm_token'
 
 export default function App() {
-  const [state, setState] = useState(null)
-  const [token, setToken] = useState(null)
+  const [state, setState]     = useState(null)
+  const [token, setToken]     = useState(null)
   const [loading, setLoading] = useState(true)
-  const [screen, setScreen] = useState('prologue')
+  const [context, setContext] = useState('actor')
 
   useEffect(() => {
     async function bootstrap() {
@@ -26,13 +29,12 @@ export default function App() {
       const saved = await loadState(tok)
       if (saved) {
         setState(saved)
-        // If background already chosen, open on ledger
-        setScreen(saved.background_id ? 'ledger' : 'prologue')
+        setContext(saved.background_id && saved.background_id !== 'unknown' ? 'forum' : 'actor')
       } else {
         const fresh = createState(tok)
         setState(fresh)
         await saveState(tok, fresh)
-        setScreen('prologue')
+        setContext('actor')
       }
       setLoading(false)
     }
@@ -44,8 +46,6 @@ export default function App() {
     await saveState(token, newState)
   }
 
-  // Called from Prologue when player confirms a background.
-  // Seeds background_id into state, saves, switches to Ledger.
   async function onSelectBackground(backgroundId) {
     const bg = BACKGROUNDS.find(b => b.id === backgroundId)
     if (!bg) return
@@ -56,15 +56,9 @@ export default function App() {
     }
     setState(updated)
     await saveState(token, updated)
-    setScreen('ledger')
+    setContext('forum')
   }
 
-  // Session abandonment — forward-looking lifecycle handler.
-  // Does not delete the old save. Appends a terminal event so the record
-  // is complete. The old save becomes a historical artefact on disk.
-  // In the Simulator this event will have social and ecological consequences
-  // for the clan — a Constructor who stops participating leaves a gap.
-  // For now: mark abandoned, generate new token, bootstrap fresh in-place.
   async function onNewGame() {
     if (state && token) {
       const abandoned = {
@@ -82,53 +76,93 @@ export default function App() {
     const fresh = createState(newTok)
     setState(fresh)
     await saveState(newTok, fresh)
-    setScreen('prologue')
+    setContext('actor')
   }
 
   if (loading) {
-    return (
-      <div className="loading">
-        <span>Consulting the ledger...</span>
-      </div>
-    )
+    return <div className="otivm-loading"><span>Consulting the ledger...</span></div>
   }
 
-  return (
-    <div>
-      <nav className="main-nav">
-        <span className="nav-title">OTIVM</span>
-        <div className="nav-links">
-          <button
-            className={`nav-btn${screen === 'prologue' ? ' active' : ''}`}
-            onClick={() => setScreen('prologue')}
-          >
-            Prologue
-          </button>
-          <button
-            className={`nav-btn${screen === 'ledger' ? ' active' : ''}`}
-            onClick={() => setScreen('ledger')}
-          >
-            Ledger
-          </button>
-          <button
-            className={`nav-btn${screen === 'map' ? ' active' : ''}`}
-            onClick={() => setScreen('map')}
-          >
-            Map
-          </button>
-        </div>
-      </nav>
-      <div className="screen-wrap">
-        <div style={{ display: screen === 'prologue' ? 'block' : 'none' }}>
-          <Prologue state={state} onSelectBackground={onSelectBackground} />
-        </div>
-        <div style={{ display: screen === 'ledger' ? 'block' : 'none' }}>
-          <Ledger state={state} onStateChange={onStateChange} onNewGame={onNewGame} />
-        </div>
-        <div style={{ display: screen === 'map' ? 'block' : 'none' }}>
-          <Map state={state} />
-        </div>
+  // Active context config for Shell
+  const activeCtx   = contextsJson.find(c => c.id === context) || contextsJson[0]
+  const subitems    = activeCtx.subitems || []
+
+  // Context header text
+  const ctxHeader = (
+    <div className="otivm-ctx-header">
+      <div>
+        <span className="otivm-ctx-eyebrow">Context</span>
+        <span className="otivm-ctx-name">{activeCtx.name} — {activeCtx.subtitle}</span>
       </div>
     </div>
   )
+
+  // Screen content
+  let screen
+  if (context === 'actor') {
+    screen = (
+      <Actor
+        state={state}
+        onSelectBackground={onSelectBackground}
+      />
+    )
+  } else if (context === 'forum') {
+    screen = (
+      <Forum
+        state={state}
+        onStateChange={onStateChange}
+        onNewGame={onNewGame}
+      />
+    )
+  } else if (context === 'map') {
+    screen = <Map state={state} />
+  }
+
+  return (
+    <Shell
+      contexts={contextsJson}
+      activeId={context}
+      onContext={setContext}
+      subitems={subitems}
+      layout={activeCtx.layout}
+      token={token}
+      onNewGame={onNewGame}
+    >
+      {ctxHeader}
+      <div className="otivm-layout-wrap">
+        {context === 'actor' && (
+          <div className={activeCtx.layout === 'three-col' ? 'otivm-layout-three-col' : ''}>
+            {activeCtx.layout === 'three-col' ? (
+              <>
+                <div>{filterCol(screen, 'left')}</div>
+                <div>{filterCol(screen, 'center')}</div>
+                <div>{filterCol(screen, 'right')}</div>
+              </>
+            ) : screen}
+          </div>
+        )}
+        {context === 'forum' && (
+          <div className={activeCtx.layout === 'two-col' ? 'otivm-layout-two-col' : ''}>
+            {activeCtx.layout === 'two-col' ? (
+              <>
+                <div>{filterCol(screen, 'left')}</div>
+                <div>{filterCol(screen, 'right')}</div>
+              </>
+            ) : screen}
+          </div>
+        )}
+        {context === 'map' && screen}
+      </div>
+    </Shell>
+  )
+}
+
+// Extract children from a screen component by their col prop.
+// Actor and Forum return arrays of Section elements with col props.
+function filterCol(screen, col) {
+  if (!screen) return null
+  const children = screen.props?.children
+  if (!children) return null
+  const arr = Array.isArray(children) ? children : [children]
+  return arr.filter(c => c?.props?.col === col)
 }