feat(sidebar): add Debug panel with copy-conversation action

New "Debug" panel option in the sidebar, grouping dev-facing actions.
Currently exposes the Copy-conversation button (ported from the old
header). Leaves room for additional debug actions without re-cluttering
the header.

The Copy action wraps `tabStore.copyConversation()` and shows a
"Copied"/"Failed" affordance for 1.5s, matching the previous header
behavior.

2 files changed, 39 insertions, 0 deletions

diff --git a/packages/frontend/src/lib/components/DebugPanel.svelte b/packages/frontend/src/lib/components/DebugPanel.svelte
new file mode 100644
index 0000000..aea1ccb
--- /dev/null
+++ b/packages/frontend/src/lib/components/DebugPanel.svelte
@@ -0,0 +1,35 @@
+<script lang="ts">
+import { tabStore } from "../tabs.svelte.js";
+
+let copyLabel = $state("Copy conversation");
+
+function resetCopyLabel(): void {
+	copyLabel = "Copy conversation";
+}
+
+async function handleCopy(): Promise<void> {
+	const text = tabStore.copyConversation();
+	try {
+		await navigator.clipboard.writeText(text);
+		copyLabel = "Copied";
+	} catch {
+		copyLabel = "Failed";
+	}
+	setTimeout(resetCopyLabel, 1500);
+}
+</script>
+
+<div class="flex flex-col gap-3">
+	<div class="text-xs font-semibold text-base-content/50 uppercase tracking-wide">Debug</div>
+
+	<div class="flex flex-col gap-2">
+		<p class="text-xs text-base-content/70">Conversation</p>
+		<p class="text-xs text-base-content/40">
+			Copy a structured plain-text dump of the active tab's conversation
+			(chunk shape included) for bug reports.
+		</p>
+		<button type="button" class="btn btn-sm btn-primary w-full" onclick={handleCopy}>
+			{copyLabel}
+		</button>
+	</div>
+</div>
diff --git a/packages/frontend/src/lib/components/SidebarPanel.svelte b/packages/frontend/src/lib/components/SidebarPanel.svelte
index 206ed09..66fa6a4 100644
--- a/packages/frontend/src/lib/components/SidebarPanel.svelte
+++ b/packages/frontend/src/lib/components/SidebarPanel.svelte
@@ -4,6 +4,7 @@ import type { CacheStats, KeyInfo, LogEntry, TaskItem } from "../types.js";
 import CacheRatePanel from "./CacheRatePanel.svelte";
 import ClaudeReset from "./ClaudeReset.svelte";
 import ConfigPanel from "./ConfigPanel.svelte";
+import DebugPanel from "./DebugPanel.svelte";
 import KeyUsage from "./KeyUsage.svelte";
 import ModelSelector from "./ModelSelector.svelte";
 import ModelStatus from "./ModelStatus.svelte";
@@ -95,6 +96,7 @@ const viewOptions = [
 	"Skills",
 	"Tools",
 	"Settings",
+	"Debug",
 ];
 
 function addPanel() {
@@ -181,6 +183,8 @@ function contentClass(_selected: string): string {
 					<ToolPermissions entries={permissionLog} {apiBase} />
 				{:else if panel.selected === "Settings"}
 					<SettingsPanel {keys} {apiBase} />
+				{:else if panel.selected === "Debug"}
+					<DebugPanel />
 				{/if}
 			</div>
 		</div>