feat: tab system with per-tab agents, DB persistence, and DaisyUI tabs-lift UI

- Add tabs, messages, and settings tables to SQLite database
- Backend: refactor AgentManager to manage per-tab Agent instances via Map<tabId, TabAgent>
- Backend: WebSocket events tagged with tabId for multiplexing
- Backend: tab CRUD routes (create, list, update, archive, messages)
- Backend: persist user and assistant messages to DB during chat
- Frontend: new tabStore replaces single chatStore with multi-tab reactive state
- Frontend: TabBar component using DaisyUI tabs-lift style with status dots
- Frontend: Settings sidebar panel for title generation model selection
- Frontend: wire ChatPanel, ChatInput, Header to use tabStore
- Fix HMR listener accumulation via wsClient.clearCallbacks()
- Delete old single-chat chatStore (chat.svelte.ts)

6 files changed, 195 insertions, 36 deletions

diff --git a/packages/frontend/src/lib/components/ChatInput.svelte b/packages/frontend/src/lib/components/ChatInput.svelte
index 92c78b9..9563a9f 100644
--- a/packages/frontend/src/lib/components/ChatInput.svelte
+++ b/packages/frontend/src/lib/components/ChatInput.svelte
@@ -1,9 +1,9 @@
 <script lang="ts">
-import { chatStore } from "../chat.svelte.js";
+import { tabStore } from "../tabs.svelte.js";
 
 let inputEl: HTMLInputElement | undefined;
 let inputValue = $state("");
-const isDisabled = $derived(chatStore.agentStatus === "running");
+const isDisabled = $derived((tabStore.activeTab?.agentStatus ?? "idle") === "running");
 
 $effect(() => {
 	inputEl?.focus();
@@ -20,7 +20,7 @@ function submit() {
 	const text = inputValue.trim();
 	if (!text || isDisabled) return;
 	inputValue = "";
-	chatStore.sendMessage(text);
+	tabStore.sendMessage(text);
 }
 </script>
 
diff --git a/packages/frontend/src/lib/components/ChatPanel.svelte b/packages/frontend/src/lib/components/ChatPanel.svelte
index 11c3b5d..24d8c7f 100644
--- a/packages/frontend/src/lib/components/ChatPanel.svelte
+++ b/packages/frontend/src/lib/components/ChatPanel.svelte
@@ -1,13 +1,14 @@
 <script lang="ts">
 	import { untrack } from "svelte";
-	import { chatStore } from "../chat.svelte.js";
-	import { wsClient } from "../ws.svelte.js";
+	import { tabStore } from "../tabs.svelte.js";
 	import ChatMessageComponent from "./ChatMessage.svelte";
 
 	let messagesEl: HTMLDivElement | undefined;
 	let userScrolledUp = $state(false);
 	let isAutoScrolling = false;
 
+	const messages = $derived(tabStore.activeTab?.messages ?? []);
+
 	function isNearBottom(el: HTMLElement): boolean {
 		return el.scrollHeight - el.scrollTop - el.clientHeight < 64;
 	}
@@ -32,8 +33,7 @@
 	}
 
 	$effect(() => {
-		// Trigger on any message appended; track length explicitly
-		const count = chatStore.messages.length;
+		const count = messages.length;
 		void count;
 		if (messagesEl) {
 			untrack(() => {
@@ -44,27 +44,6 @@
 </script>
 
 <div class="flex flex-col h-full">
-	<!-- Status bar -->
-	<div class="flex items-center gap-3 px-4 py-2 bg-base-200 border-b border-base-300 text-xs">
-		<span class="flex items-center gap-1.5">
-			<span class="status status-sm {wsClient.connectionStatus === 'connected' ? 'status-success' : wsClient.connectionStatus === 'connecting' ? 'status-warning' : 'status-error'}"></span>
-			<span class="capitalize text-base-content/70">{wsClient.connectionStatus}</span>
-		</span>
-		<span class="text-base-content/50">|</span>
-		<span class="text-base-content/70">
-			Agent:
-			<span
-				class="font-semibold {chatStore.agentStatus === 'running'
-					? 'text-warning'
-					: chatStore.agentStatus === 'error'
-						? 'text-error'
-						: 'text-success'}"
-			>
-				{chatStore.agentStatus === "running" ? "running..." : chatStore.agentStatus}
-			</span>
-		</span>
-	</div>
-
 	<!-- Messages -->
 	<div class="relative flex-1 min-h-0">
 		<div
@@ -75,12 +54,12 @@
 				isAutoScrolling = false;
 			}}
 		>
-			{#if chatStore.messages.length === 0}
+			{#if messages.length === 0}
 				<div class="flex items-center justify-center h-full text-base-content/40 text-sm">
 					Send a message to start a conversation
 				</div>
 			{/if}
-			{#each chatStore.messages as message (message.id)}
+			{#each messages as message (message.id)}
 				<ChatMessageComponent {message} />
 			{/each}
 		</div>
diff --git a/packages/frontend/src/lib/components/Header.svelte b/packages/frontend/src/lib/components/Header.svelte
index 721a773..ada5500 100644
--- a/packages/frontend/src/lib/components/Header.svelte
+++ b/packages/frontend/src/lib/components/Header.svelte
@@ -1,5 +1,6 @@
 <script lang="ts">
-import { chatStore } from "../chat.svelte.js";
+import { tabStore } from "../tabs.svelte.js";
+import { wsClient } from "../ws.svelte.js";
 import ThemeSwitcher from "./ThemeSwitcher.svelte";
 
 const { onToggleSidebar }: { onToggleSidebar: () => void } = $props();
@@ -12,7 +13,7 @@ function resetCopyLabel() {
 }
 
 async function handleCopy() {
-	const text = chatStore.copyConversation();
+	const text = tabStore.copyConversation();
 	try {
 		await navigator.clipboard.writeText(text);
 		copyLabel = "Copied";
@@ -29,8 +30,9 @@ async function handleCopy() {
 		<span class="text-xl font-bold tracking-tight">Dispatch</span>
 	</div>
 	<div class="navbar-end flex items-center gap-3">
-		<span class="text-xs text-base-content/60 hidden sm:block">
-			{chatStore.activeModelId ?? "Default Model"}
+		<span class="flex items-center gap-1.5 text-xs text-base-content/60">
+			<span class="status status-sm {wsClient.connectionStatus === 'connected' ? 'status-success' : wsClient.connectionStatus === 'connecting' ? 'status-warning' : 'status-error'}"></span>
+			<span class="capitalize">{wsClient.connectionStatus}</span>
 		</span>
 		<button
 			type="button"
@@ -54,7 +56,7 @@ async function handleCopy() {
 			onclick={onToggleSidebar}
 			aria-label="Toggle sidebar"
 		>
-			☰ Sidebar
+			Sidebar
 		</button>
 	</div>
 </header>
diff --git a/packages/frontend/src/lib/components/SettingsPanel.svelte b/packages/frontend/src/lib/components/SettingsPanel.svelte
new file mode 100644
index 0000000..8449aa4
--- /dev/null
+++ b/packages/frontend/src/lib/components/SettingsPanel.svelte
@@ -0,0 +1,128 @@
+<script lang="ts">
+	import type { KeyInfo } from "../types.js";
+
+	const {
+		keys = [],
+		apiBase = "",
+	}: {
+		keys?: KeyInfo[];
+		apiBase?: string;
+	} = $props();
+
+	let titleKeyId = $state<string | null>(null);
+	let titleModelId = $state<string | null>(null);
+	let availableModels = $state<string[]>([]);
+	let loadingModels = $state(false);
+	let saving = $state(false);
+	let saved = $state(false);
+
+	async function loadSettings(): Promise<void> {
+		try {
+			const res = await fetch(`${apiBase}/tabs/settings/title-model`);
+			if (!res.ok) return;
+			const data = await res.json() as { keyId: string | null; modelId: string | null };
+			titleKeyId = data.keyId;
+			if (titleKeyId) {
+				await loadModelsForKey(titleKeyId);
+			}
+			// Set model AFTER options are loaded so the select can match the value
+			titleModelId = data.modelId;
+		} catch {
+			// ignore
+		}
+	}
+
+	async function loadModelsForKey(keyId: string): Promise<void> {
+		loadingModels = true;
+		try {
+			const res = await fetch(`${apiBase}/models/available?keyId=${encodeURIComponent(keyId)}`);
+			if (!res.ok) { availableModels = []; return; }
+			const data = await res.json() as { models: string[] };
+			availableModels = data.models ?? [];
+		} catch {
+			availableModels = [];
+		} finally {
+			loadingModels = false;
+		}
+	}
+
+	async function onKeyChange(e: Event): Promise<void> {
+		const select = e.target as HTMLSelectElement;
+		titleKeyId = select.value || null;
+		titleModelId = null;
+		availableModels = [];
+		if (titleKeyId) {
+			await loadModelsForKey(titleKeyId);
+		}
+	}
+
+	async function onModelChange(e: Event): Promise<void> {
+		const select = e.target as HTMLSelectElement;
+		titleModelId = select.value || null;
+	}
+
+	async function saveSettings(): Promise<void> {
+		saving = true;
+		try {
+			await fetch(`${apiBase}/tabs/settings/title-model`, {
+				method: "PUT",
+				headers: { "Content-Type": "application/json" },
+				body: JSON.stringify({ keyId: titleKeyId, modelId: titleModelId }),
+			});
+			saved = true;
+			setTimeout(() => { saved = false; }, 2000);
+		} catch {
+			// ignore
+		} finally {
+			saving = false;
+		}
+	}
+
+	$effect(() => {
+		void loadSettings();
+	});
+</script>
+
+<div class="flex flex-col gap-3">
+	<div class="text-xs font-semibold text-base-content/50 uppercase tracking-wide">Settings</div>
+
+	<div class="flex flex-col gap-2">
+		<p class="text-xs text-base-content/70">Title Generation Model</p>
+		<p class="text-xs text-base-content/40">Used to generate short titles for new tabs after the first message.</p>
+
+		<label class="text-xs text-base-content/60">Key</label>
+		<select class="select select-bordered select-sm w-full" onchange={onKeyChange} value={titleKeyId ?? ""}>
+			<option value="">Select a key...</option>
+			{#each keys as key (key.id)}
+				<option value={key.id}>{key.id} ({key.provider})</option>
+			{/each}
+		</select>
+
+		<label class="text-xs text-base-content/60">Model</label>
+		<select
+			class="select select-bordered select-sm w-full"
+			onchange={onModelChange}
+			value={titleModelId ?? ""}
+			disabled={!titleKeyId || loadingModels}
+		>
+			<option value="">{loadingModels ? "Loading models..." : "Select a model..."}</option>
+			{#each availableModels as model (model)}
+				<option value={model}>{model}</option>
+			{/each}
+		</select>
+
+		<button
+			class="btn btn-sm btn-primary w-full mt-1"
+			disabled={saving || !titleKeyId || !titleModelId}
+			onclick={saveSettings}
+		>
+			{#if saving}
+				<span class="loading loading-spinner loading-xs"></span>
+			{:else if saved}
+				Saved
+			{:else}
+				Save
+			{/if}
+		</button>
+	</div>
+</div>
diff --git a/packages/frontend/src/lib/components/SidebarPanel.svelte b/packages/frontend/src/lib/components/SidebarPanel.svelte
index e5536de..7e71bd5 100644
--- a/packages/frontend/src/lib/components/SidebarPanel.svelte
+++ b/packages/frontend/src/lib/components/SidebarPanel.svelte
@@ -7,6 +7,7 @@
 	import PermissionLog from "./PermissionLog.svelte";
 	import KeyUsage from "./KeyUsage.svelte";
 	import ClaudeReset from "./ClaudeReset.svelte";
+	import SettingsPanel from "./SettingsPanel.svelte";
 	import type { TaskItem, LogEntry, KeyInfo } from "../types.js";
 
 	const {
@@ -41,7 +42,7 @@
 	let nextId = 0;
 	let panels = $state<Panel[]>([{ id: nextId++, selected: "Current Model" }]);
 
-	const viewOptions = ["Select a view", "Current Model", "Key Usage", "Claude Reset", "Model Status", "Tasks", "Config", "Skills", "Permission Log"];
+	const viewOptions = ["Select a view", "Current Model", "Key Usage", "Claude Reset", "Model Status", "Tasks", "Config", "Skills", "Permission Log", "Settings"];
 
 	function addPanel() {
 		panels = [...panels, { id: nextId++, selected: "Select a view" }];
@@ -114,6 +115,8 @@
 					<SkillsBrowser {apiBase} />
 				{:else if panel.selected === "Permission Log"}
 					<PermissionLog entries={permissionLog} />
+				{:else if panel.selected === "Settings"}
+					<SettingsPanel {keys} {apiBase} />
 				{/if}
 			</div>
 		</div>
diff --git a/packages/frontend/src/lib/components/TabBar.svelte b/packages/frontend/src/lib/components/TabBar.svelte
new file mode 100644
index 0000000..d1a3936
--- /dev/null
+++ b/packages/frontend/src/lib/components/TabBar.svelte
@@ -0,0 +1,47 @@
+<script lang="ts">
+	import { tabStore } from "../tabs.svelte.js";
+
+	function statusColor(status: string): string {
+		if (status === "running") return "bg-warning";
+		if (status === "error") return "bg-error";
+		return "bg-success";
+	}
+</script>
+
+<div class="overflow-x-auto bg-base-200 flex-shrink-0">
+	<div role="tablist" class="tabs tabs-lift min-w-max">
+		<!-- New tab button — always first -->
+		<button
+			type="button"
+			class="tab"
+			onclick={() => tabStore.createNewTab()}
+			aria-label="New tab"
+		>
+			+
+		</button>
+
+		{#each tabStore.tabs as tab (tab.id)}
+			<!-- svelte-ignore a11y_no_static_element_interactions -->
+			<div
+				role="tab"
+				class="tab {tab.id === tabStore.activeTabId ? 'tab-active' : ''}"
+				onclick={() => tabStore.switchTab(tab.id)}
+				onkeydown={(e) => { if (e.key === 'Enter' || e.key === ' ') tabStore.switchTab(tab.id); }}
+				tabindex="0"
+			>
+				<span class="flex items-center gap-1.5">
+					<span class="w-1.5 h-1.5 rounded-full shrink-0 {statusColor(tab.agentStatus)}"></span>
+					<span class="max-w-32 truncate text-xs">{tab.title}</span>
+					<button
+						type="button"
+						class="ml-0.5 text-base-content/30 hover:text-error transition-colors text-xs leading-none"
+						onclick={(e) => { e.stopPropagation(); tabStore.closeTab(tab.id); }}
+						aria-label="Close tab"
+					>
+						x
+					</button>
+				</span>
+			</div>
+		{/each}
+	</div>
+</div>