feat(v2): add tiling layout, sidebar controls, and keyboard shortcuts

- TilingGrid: dynamic CSS Grid with auto-preset based on pane count
- Layout presets: 1-col, 2-col, 3-col, 2x2, master-stack
- PaneContainer: close button, status indicator, focus highlight
- SessionList: new terminal button, layout preset selector, pane list
- Layout store: pane CRUD, focus management, grid template generation
- Keyboard: Ctrl+N new terminal, Ctrl+1-4 focus pane by index

v2/src/App.svelte

@@ -1,6 +1,39 @@
 <script lang="ts">
+  import { onMount } from 'svelte';
   import SessionList from './lib/components/Sidebar/SessionList.svelte';
   import TilingGrid from './lib/components/Layout/TilingGrid.svelte';
+  import { addPane, focusPaneByIndex, getPanes } from './lib/stores/layout';
+
+  function newTerminal() {
+    const id = crypto.randomUUID();
+    const num = getPanes().length + 1;
+    addPane({
+      id,
+      type: 'terminal',
+      title: `Terminal ${num}`,
+    });
+  }
+
+  onMount(() => {
+    function handleKeydown(e: KeyboardEvent) {
+      // Ctrl+N — new terminal
+      if (e.ctrlKey && !e.shiftKey && e.key === 'n') {
+        e.preventDefault();
+        newTerminal();
+        return;
+      }
+
+      // Ctrl+1-4 — focus pane by index
+      if (e.ctrlKey && !e.shiftKey && e.key >= '1' && e.key <= '4') {
+        e.preventDefault();
+        focusPaneByIndex(parseInt(e.key) - 1);
+        return;
+      }
+    }
+
+    window.addEventListener('keydown', handleKeydown);
+    return () => window.removeEventListener('keydown', handleKeydown);
+  });
 </script>
 
 <aside class="sidebar">

v2/src/lib/components/Layout/PaneContainer.svelte

@@ -3,15 +3,25 @@
 
   interface Props {
     title: string;
+    status?: 'idle' | 'running' | 'error' | 'done';
+    onClose?: () => void;
     children: Snippet;
   }
 
-  let { title, children }: Props = $props();
+  let { title, status = 'idle', onClose, children }: Props = $props();
 </script>
 
 <div class="pane-container">
   <div class="pane-header">
     <span class="pane-title">{title}</span>
+    <div class="pane-controls">
+      {#if status !== 'idle'}
+        <span class="status {status}">{status}</span>
+      {/if}
+      {#if onClose}
+        <button class="close-btn" onclick={onClose} title="Close pane">&times;</button>
+      {/if}
+    </div>
   </div>
   <div class="pane-content">
     {@render children()}
@@ -26,12 +36,14 @@
     border-radius: var(--border-radius);
     overflow: hidden;
     border: 1px solid var(--border);
+    height: 100%;
   }
 
   .pane-header {
     height: var(--pane-header-height);
     display: flex;
     align-items: center;
+    justify-content: space-between;
     padding: 0 10px;
     background: var(--bg-tertiary);
     border-bottom: 1px solid var(--border);
@@ -47,8 +59,39 @@
     text-overflow: ellipsis;
   }
 
+  .pane-controls {
+    display: flex;
+    align-items: center;
+    gap: 6px;
+  }
+
+  .status {
+    font-size: 10px;
+    padding: 1px 5px;
+    border-radius: 3px;
+  }
+
+  .status.running { color: var(--ctp-blue); }
+  .status.error { color: var(--ctp-red); }
+  .status.done { color: var(--ctp-green); }
+
+  .close-btn {
+    background: none;
+    border: none;
+    color: var(--text-muted);
+    font-size: 16px;
+    cursor: pointer;
+    padding: 0 2px;
+    line-height: 1;
+  }
+
+  .close-btn:hover {
+    color: var(--ctp-red);
+  }
+
   .pane-content {
     flex: 1;
-    overflow: auto;
+    overflow: hidden;
+    min-height: 0;
   }
 </style>

v2/src/lib/components/Layout/TilingGrid.svelte

@@ -1,33 +1,84 @@
 <script lang="ts">
   import PaneContainer from './PaneContainer.svelte';
+  import TerminalPane from '../Terminal/TerminalPane.svelte';
+  import {
+    getPanes,
+    getGridTemplate,
+    getPaneGridArea,
+    focusPane,
+    removePane,
+  } from '../../stores/layout';
 
-  // Phase 2: dynamic pane management, resize, presets
+  let gridTemplate = $derived(getGridTemplate());
-  // For now: single empty pane as placeholder
+  let panes = $derived(getPanes());
 </script>
 
-<div class="tiling-grid">
+<div
-  <PaneContainer title="Welcome">
+  class="tiling-grid"
-    <div class="welcome">
+  style:grid-template-columns={gridTemplate.columns}
+  style:grid-template-rows={gridTemplate.rows}
+>
+  {#if panes.length === 0}
+    <div class="empty-state">
       <h1>BTerminal v2</h1>
       <p>Claude Agent Mission Control</p>
-      <div class="status">
+      <p class="hint">Press <kbd>Ctrl+N</kbd> to open a terminal</p>
-        <span class="badge">Phase 1 — Scaffold</span>
-      </div>
     </div>
-  </PaneContainer>
+  {:else}
+    {#each panes as pane, i (pane.id)}
+      {@const gridArea = getPaneGridArea(i)}
+      <!-- svelte-ignore a11y_click_events_have_key_events -->
+      <!-- svelte-ignore a11y_no_static_element_interactions -->
+      <div
+        class="pane-slot"
+        class:focused={pane.focused}
+        style:grid-area={gridArea}
+        onclick={() => focusPane(pane.id)}
+      >
+        <PaneContainer
+          title={pane.title}
+          status={pane.focused ? 'running' : 'idle'}
+          onClose={() => removePane(pane.id)}
+        >
+          {#if pane.type === 'terminal'}
+            <TerminalPane
+              shell={pane.shell}
+              cwd={pane.cwd}
+              args={pane.args}
+              onExit={() => removePane(pane.id)}
+            />
+          {:else}
+            <div class="placeholder">
+              <p>{pane.type} pane — coming in Phase 3/4</p>
+            </div>
+          {/if}
+        </PaneContainer>
+      </div>
+    {/each}
+  {/if}
 </div>
 
 <style>
   .tiling-grid {
     display: grid;
-    grid-template-columns: 1fr;
-    grid-template-rows: 1fr;
     gap: var(--pane-gap);
     height: 100%;
     padding: var(--pane-gap);
   }
 
-  .welcome {
+  .pane-slot {
+    min-width: 0;
+    min-height: 0;
+    border-radius: var(--border-radius);
+    overflow: hidden;
+  }
+
+  .pane-slot.focused {
+    outline: 1px solid var(--accent);
+    outline-offset: -1px;
+  }
+
+  .empty-state {
     display: flex;
     flex-direction: column;
     align-items: center;
@@ -37,22 +88,33 @@
     color: var(--text-muted);
   }
 
-  .welcome h1 {
+  .empty-state h1 {
     font-size: 24px;
     font-weight: 700;
     color: var(--text-primary);
   }
 
-  .welcome p {
+  .empty-state p { font-size: 14px; }
-    font-size: 14px;
+
+  .hint {
+    margin-top: 8px;
+    font-size: 12px;
+    color: var(--ctp-overlay0);
   }
 
-  .badge {
+  kbd {
     background: var(--bg-surface);
-    color: var(--accent);
+    padding: 2px 6px;
-    padding: 4px 12px;
+    border-radius: 3px;
-    border-radius: var(--border-radius);
+    font-size: 11px;
+  }
+
+  .placeholder {
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    height: 100%;
+    color: var(--text-muted);
     font-size: 12px;
-    margin-top: 8px;
   }
 </style>

v2/src/lib/components/Sidebar/SessionList.svelte

@@ -1,27 +1,127 @@
 <script lang="ts">
-  // Phase 4: session CRUD, groups, types
+  import {
+    getPanes,
+    addPane,
+    focusPane,
+    removePane,
+    getActivePreset,
+    setPreset,
+    type LayoutPreset,
+  } from '../../stores/layout';
+
+  let panes = $derived(getPanes());
+  let preset = $derived(getActivePreset());
+
+  const presets: LayoutPreset[] = ['1-col', '2-col', '3-col', '2x2', 'master-stack'];
+
+  function newTerminal() {
+    const id = crypto.randomUUID();
+    const num = panes.length + 1;
+    addPane({
+      id,
+      type: 'terminal',
+      title: `Terminal ${num}`,
+    });
+  }
 </script>
 
 <div class="session-list">
   <div class="header">
     <h2>Sessions</h2>
+    <button class="new-btn" onclick={newTerminal} title="New terminal (Ctrl+N)">+</button>
   </div>
-  <div class="empty-state">
+
-    <p>No sessions yet.</p>
+  <div class="layout-presets">
-    <p class="hint">Phase 2 will add terminal sessions.</p>
+    {#each presets as p}
+      <button
+        class="preset-btn"
+        class:active={preset === p}
+        onclick={() => setPreset(p)}
+        title={p}
+      >{p}</button>
+    {/each}
   </div>
+
+  {#if panes.length === 0}
+    <div class="empty-state">
+      <p>No sessions yet.</p>
+      <p class="hint">Click + or press Ctrl+N</p>
+    </div>
+  {:else}
+    <ul class="pane-list">
+      {#each panes as pane (pane.id)}
+        <li class="pane-item" class:focused={pane.focused}>
+          <button class="pane-btn" onclick={() => focusPane(pane.id)}>
+            <span class="pane-icon">{pane.type === 'terminal' ? '>' : '#'}</span>
+            <span class="pane-name">{pane.title}</span>
+          </button>
+          <button class="remove-btn" onclick={() => removePane(pane.id)}>&times;</button>
+        </li>
+      {/each}
+    </ul>
+  {/if}
 </div>
 
 <style>
   .session-list {
     padding: 12px;
+    display: flex;
+    flex-direction: column;
+    gap: 8px;
+  }
+
+  .header {
+    display: flex;
+    align-items: center;
+    justify-content: space-between;
   }
 
   .header h2 {
     font-size: 14px;
     font-weight: 600;
     color: var(--text-primary);
-    margin-bottom: 12px;
+  }
+
+  .new-btn {
+    background: var(--bg-surface);
+    border: 1px solid var(--border);
+    color: var(--text-primary);
+    width: 24px;
+    height: 24px;
+    border-radius: var(--border-radius);
+    cursor: pointer;
+    font-size: 16px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+  }
+
+  .new-btn:hover {
+    background: var(--bg-surface-hover);
+    color: var(--accent);
+  }
+
+  .layout-presets {
+    display: flex;
+    gap: 2px;
+    flex-wrap: wrap;
+  }
+
+  .preset-btn {
+    background: var(--bg-surface);
+    border: 1px solid var(--border);
+    color: var(--text-muted);
+    font-size: 9px;
+    padding: 2px 5px;
+    border-radius: 3px;
+    cursor: pointer;
+  }
+
+  .preset-btn:hover { color: var(--text-primary); }
+  .preset-btn.active {
+    background: var(--accent);
+    color: var(--ctp-crust);
+    border-color: var(--accent);
   }
 
   .empty-state {
@@ -36,4 +136,62 @@
     font-size: 11px;
     color: var(--ctp-overlay0);
   }
+
+  .pane-list {
+    list-style: none;
+    display: flex;
+    flex-direction: column;
+    gap: 2px;
+  }
+
+  .pane-item {
+    display: flex;
+    align-items: center;
+    border-radius: var(--border-radius);
+  }
+
+  .pane-item.focused {
+    background: var(--bg-surface);
+  }
+
+  .pane-btn {
+    flex: 1;
+    background: none;
+    border: none;
+    color: var(--text-secondary);
+    font-size: 12px;
+    padding: 4px 6px;
+    cursor: pointer;
+    display: flex;
+    align-items: center;
+    gap: 6px;
+    text-align: left;
+  }
+
+  .pane-btn:hover { color: var(--text-primary); }
+
+  .pane-icon {
+    color: var(--ctp-green);
+    font-weight: bold;
+    font-size: 11px;
+  }
+
+  .pane-name {
+    overflow: hidden;
+    text-overflow: ellipsis;
+    white-space: nowrap;
+  }
+
+  .remove-btn {
+    background: none;
+    border: none;
+    color: var(--text-muted);
+    cursor: pointer;
+    font-size: 14px;
+    padding: 2px 4px;
+    opacity: 0;
+  }
+
+  .pane-item:hover .remove-btn { opacity: 1; }
+  .remove-btn:hover { color: var(--ctp-red); }
 </style>

v2/src/lib/stores/layout.ts

@@ -1,28 +1,90 @@
-// Layout state management — Svelte 5 runes
-// Phase 2: pane positions, resize, presets
-
 export type LayoutPreset = '1-col' | '2-col' | '3-col' | '2x2' | 'master-stack';
 
-export interface PaneState {
+export type PaneType = 'terminal' | 'agent' | 'markdown' | 'empty';
+
+export interface Pane {
   id: string;
-  sessionId: string;
+  type: PaneType;
-  row: number;
+  title: string;
-  col: number;
+  shell?: string;
-  rowSpan: number;
+  cwd?: string;
-  colSpan: number;
+  args?: string[];
+  focused: boolean;
 }
 
+let panes = $state<Pane[]>([]);
 let activePreset = $state<LayoutPreset>('1-col');
-let panes = $state<PaneState[]>([]);
+let focusedPaneId = $state<string | null>(null);
 
-export function getActivePreset() {
+export function getPanes(): Pane[] {
+  return panes;
+}
+
+export function getActivePreset(): LayoutPreset {
   return activePreset;
 }
 
-export function setPreset(preset: LayoutPreset) {
+export function getFocusedPaneId(): string | null {
+  return focusedPaneId;
+}
+
+export function addPane(pane: Omit<Pane, 'focused'>): void {
+  panes.push({ ...pane, focused: false });
+  focusPane(pane.id);
+  autoPreset();
+}
+
+export function removePane(id: string): void {
+  panes = panes.filter(p => p.id !== id);
+  if (focusedPaneId === id) {
+    focusedPaneId = panes.length > 0 ? panes[0].id : null;
+  }
+  autoPreset();
+}
+
+export function focusPane(id: string): void {
+  focusedPaneId = id;
+  panes = panes.map(p => ({ ...p, focused: p.id === id }));
+}
+
+export function focusPaneByIndex(index: number): void {
+  if (index >= 0 && index < panes.length) {
+    focusPane(panes[index].id);
+  }
+}
+
+export function setPreset(preset: LayoutPreset): void {
   activePreset = preset;
 }
 
-export function getPanes() {
+function autoPreset(): void {
-  return panes;
+  const count = panes.length;
+  if (count <= 1) activePreset = '1-col';
+  else if (count === 2) activePreset = '2-col';
+  else if (count === 3) activePreset = 'master-stack';
+  else activePreset = '2x2';
+}
+
+/** CSS grid-template for current preset */
+export function getGridTemplate(): { columns: string; rows: string } {
+  switch (activePreset) {
+    case '1-col':
+      return { columns: '1fr', rows: '1fr' };
+    case '2-col':
+      return { columns: '1fr 1fr', rows: '1fr' };
+    case '3-col':
+      return { columns: '1fr 1fr 1fr', rows: '1fr' };
+    case '2x2':
+      return { columns: '1fr 1fr', rows: '1fr 1fr' };
+    case 'master-stack':
+      return { columns: '2fr 1fr', rows: '1fr 1fr' };
+  }
+}
+
+/** For master-stack: first pane spans full height */
+export function getPaneGridArea(index: number): string | undefined {
+  if (activePreset === 'master-stack' && index === 0) {
+    return '1 / 1 / 3 / 2';
+  }
+  return undefined;
 }