diff --git a/app/globals.css b/app/globals.css
index 7ad08e1..12b4b32 100644
--- a/app/globals.css
+++ b/app/globals.css
@@ -305,3 +305,39 @@ body {
 		animation: none;
 	}
 }
+
+/* ─────────────────────────────────────────────────────────────────────────
+   Electron merged chrome (owner, 2026-09-17). The system title bar is
+   hidden (titleBarStyle: "hiddenInset" in electron/main.cjs); the app's
+   own 60px header bands are the drag surface. Everything here is inert
+   in the plain browser — it keys off <html class="lh-electron">, which
+   SidebarProvider sets after mount when it detects the Electron shell.
+
+   - .lh-drag        window-drag region (must sit on pointer-receiving els)
+   - .lh-no-drag     carve-out for interactive elements inside a drag band
+   - .lh-lights-gutter  the sidebar LH band's traffic-light gutter: lights
+                       end at x≈68, the wordmark starts at 80px (5rem)
+   - .lh-closed-toggle  same gutter for the sidebar toggle when the sidebar
+                       is closed — the lights are static, the toggle moves
+   - .lh-float-drag  the home header strip floats pointer-events-none over
+                       the graph; only in Electron does it claim events and
+                       become the drag surface for that page
+   ───────────────────────────────────────────────────────────────────────── */
+.lh-electron .lh-drag {
+	-webkit-app-region: drag;
+}
+.lh-electron .lh-no-drag {
+	-webkit-app-region: no-drag;
+}
+/* 92px = measured lights' right edge (~75pt) + the lights' own 16px
+   inset from the window edge — comfortable, symmetric air (owner). */
+.lh-electron .lh-lights-gutter {
+	padding-left: 92px;
+}
+.lh-electron .lh-closed-toggle {
+	margin-left: 92px;
+}
+.lh-electron .lh-float-drag {
+	pointer-events: auto;
+	-webkit-app-region: drag;
+}
diff --git a/components/chat.tsx b/components/chat.tsx
index 2594701..446119c 100644
--- a/components/chat.tsx
+++ b/components/chat.tsx
@@ -637,7 +637,7 @@ export function Chat({
 				    60px is an ALIGNMENT, not just a size: it equals the sidebar's
 				    LH wordmark band, so the header's border-b continues that
 				    band's bottom edge as one line across the app (owner, round 6). */}
-				<header className="flex h-15 items-center gap-3 border-b border-border px-3">
+				<header className="lh-drag flex h-15 items-center gap-3 border-b border-border px-3">
 					<SidebarToggle />
 					{renaming ? (
 						<input
@@ -651,9 +651,10 @@ export function Chat({
 							onBlur={() => void commitRename(titleDraft)}
 							spellCheck={false}
 							aria-label="Session title"
-							className="min-w-0 flex-1 bg-transparent font-title text-3xl tracking-tight caret-current outline-none"
+							className="lh-no-drag min-w-0 flex-1 bg-transparent font-title text-3xl tracking-tight caret-current outline-none"
 						/>
 					) : (
+					<>
 						<button
 							type="button"
 							title="Rename session"
@@ -661,10 +662,14 @@ export function Chat({
 								setTitleDraft(titleText);
 								setRenaming(true);
 							}}
-							className="min-w-0 flex-1 cursor-text truncate text-left font-title text-3xl tracking-tight"
+							className="lh-no-drag -mx-1.5 min-w-4 shrink cursor-text truncate rounded-md px-1.5 text-left font-title text-3xl tracking-tight transition-colors hover:bg-accent"
 						>
 							{titleText}
-						</button>
+							</button>
+							{/* flex-1 spacer: keeps the chips at the right edge AND stays a
+							    drag surface (no carve-out) — the freed bar is grippable. */}
+							<div className="min-w-4 flex-1" aria-hidden="true" />
+					</>
 					)}
 					{/* The plan chip (owner, plan-placement round): session-level
 					    structure beside the phase chip — access to the full-DAG popup
@@ -675,7 +680,7 @@ export function Chat({
 							data-testid="plan-chip"
 							onClick={() => setPlanOpen(true)}
 							title="Open the full plan"
-							className="flex shrink-0 cursor-pointer items-center gap-1.5 rounded-full border border-border/80 px-2 py-0.5 text-xs font-medium uppercase tracking-wide text-muted-foreground transition-colors hover:border-border hover:text-foreground"
+							className="lh-no-drag flex shrink-0 cursor-pointer items-center gap-1.5 rounded-full border border-border/80 px-2 py-0.5 text-xs font-medium uppercase tracking-wide text-muted-foreground transition-colors hover:border-border hover:text-foreground"
 						>
 							<WaypointsIcon className="size-3.5 text-primary" aria-hidden />
 							Plan
diff --git a/components/home.tsx b/components/home.tsx
index 30a3053..4ea95de 100644
--- a/components/home.tsx
+++ b/components/home.tsx
@@ -60,7 +60,7 @@ export function Home() {
 
 			{/* Header floats over the graph — pointer-events-none except the
 			    toggle, so the canvas stays draggable/hoverable around it. */}
-			<header className="pointer-events-none absolute inset-x-0 top-0 flex items-center gap-2 px-3 py-2">
+			<header className="lh-float-drag pointer-events-none absolute inset-x-0 top-0 flex items-center gap-2 px-3 py-2">
 				<div className="pointer-events-auto">
 					<SidebarToggle />
 				</div>
diff --git a/components/lh-mark.tsx b/components/lh-mark.tsx
new file mode 100644
index 0000000..b8778f6
--- /dev/null
+++ b/components/lh-mark.tsx
@@ -0,0 +1,42 @@
+/**
+ * LhMark — the app mark (owner's icon-no-padding.svg, 2026-09-17), inlined
+ * as JSX so it rides along with the components (no network fetch, recolorable,
+ * crisp at any size). 806×806 viewBox, no padding: sizing/padding is the
+ * consumer's job. The gray path is the harness spiral; the white ring is
+ * the mark's own stroke on dark backgrounds.
+ *
+ * Replaces the "LH" wordmark text in the sidebar band (also the traffic-light
+ * gutter's resident in the merged desktop chrome).
+ */
+export function LhMark({ className = "" }: { className?: string }) {
+	return (
+		<svg
+			viewBox="0 0 806 806"
+			className={className}
+			style={{ fillRule: "evenodd", clipRule: "evenodd", strokeLinejoin: "round", strokeMiterlimit: 2 }}
+			aria-hidden="true"
+		>
+			<g transform="matrix(1,0,0,1,-109.002299,-109.002299)">
+				<g transform="matrix(0.939904,0,0,0.939904,30.769428,30.766742)">
+					<g transform="matrix(-0.232199,0,0,0.232199,1384.403797,-416.791824)">
+						<g transform="matrix(0.573992,-2.142166,2.142166,0.573992,-5516.07298,4432.117471)">
+							<path
+								d="M1234.728,3305.937C871.642,3324.965 587,3624.915 587,3988.5C587,4365.734 893.266,4672 1270.5,4672C1647.734,4672 1954,4365.734 1954,3988.5C1954,3880.637 1928.472,3774.304 1879.503,3678.197L1794.243,3721.64C1836.356,3804.292 1858.31,3895.737 1858.31,3988.5C1858.31,4312.921 1594.921,4576.31 1270.5,4576.31C946.079,4576.31 682.69,4312.921 682.69,3988.5C682.69,3675.817 927.482,3417.86 1239.736,3401.496L1234.728,3305.937Z"
+								style={{ fill: "rgb(148,148,148)" }}
+							/>
+						</g>
+						<g transform="matrix(1.261034,-0,-0,1.261034,1170.373407,-2014.261188)">
+							<path
+								d="M1270.5,3305C893.266,3305 587,3611.266 587,3988.5C587,4365.734 893.266,4672 1270.5,4672C1647.734,4672 1954,4365.734 1954,3988.5C1954,3611.266 1647.734,3305 1270.5,3305ZM1270.5,3471.537C1555.819,3471.537 1787.463,3703.181 1787.463,3988.5C1787.463,4273.819 1555.819,4505.463 1270.5,4505.463C985.181,4505.463 753.537,4273.819 753.537,3988.5C753.537,3703.181 985.181,3471.537 1270.5,3471.537Z"
+								style={{ fill: "#fff" }}
+							/>
+						</g>
+						<g transform="matrix(1.261034,0,-0,1.261034,3139.627182,-45.007413)">
+							<circle cx="1270.5" cy="3988.5" r="683.5" style={{ fill: "#fff" }} />
+						</g>
+					</g>
+				</g>
+			</g>
+		</svg>
+	);
+}
diff --git a/components/new-session.tsx b/components/new-session.tsx
index cf5dfbf..3c66e76 100644
--- a/components/new-session.tsx
+++ b/components/new-session.tsx
@@ -79,7 +79,7 @@ export function DraftShell({
 			<div className="flex min-w-0 flex-1 flex-col">
 				{/* h-15 (60px) matches the chat header and the sidebar's LH wordmark
 			    band (owner, round 6). */}
-			<header className="relative flex h-15 items-center gap-3 px-3">
+			<header className="lh-drag relative flex h-15 items-center gap-3 px-3">
 					<SidebarToggle />
 					<div className="min-w-0 flex-1 truncate font-title text-3xl tracking-tight">New session</div>
 					<PhaseChip phase="probe" />
diff --git a/components/phase-divider.tsx b/components/phase-divider.tsx
index 9d6f617..c9c6ff5 100644
--- a/components/phase-divider.tsx
+++ b/components/phase-divider.tsx
@@ -39,7 +39,7 @@ export function PhaseChip({ phase }: { phase: Phase3 }) {
 			data-testid="phase-chip"
 			data-phase={phase}
 			title={`Session phase: ${CHIP_LABEL[phase]}`}
-			className="flex shrink-0 items-center rounded-full border border-border/80 px-2 py-0.5 text-xs font-medium uppercase tracking-wide text-muted-foreground"
+			className="lh-no-drag flex shrink-0 items-center rounded-full border border-border/80 px-2 py-0.5 text-xs font-medium uppercase tracking-wide text-muted-foreground"
 		>
 			{CHIP_LABEL[phase]}
 		</span>
diff --git a/components/sidebar.tsx b/components/sidebar.tsx
index d138dd0..5a3927d 100644
--- a/components/sidebar.tsx
+++ b/components/sidebar.tsx
@@ -5,6 +5,7 @@ import Link from "next/link";
 import { usePathname, useRouter } from "next/navigation";
 import { PanelLeftCloseIcon, PanelLeftOpenIcon, PlusIcon, SearchIcon } from "lucide-react";
 import { ActivitySection } from "@/components/activity-dock";
+import { LhMark } from "@/components/lh-mark";
 import { BrailleSpinner } from "@/components/braille-spinner";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
@@ -36,6 +37,15 @@ export function SidebarProvider({ children }: { children: React.ReactNode }) {
 	const [mounted, setMounted] = useState(false);
 
 	useEffect(() => {
+		// Electron shell detection (merged chrome, 2026-09-17): keys the
+		// .lh-electron CSS (app/globals.css) that turns the header bands
+		// into the window's drag surface. Post-mount only — server HTML
+		// and first client render must agree (no hydration mismatch),
+		// and in the plain browser the class never appears.
+		if (typeof navigator !== "undefined" && navigator.userAgent.includes("Electron")) {
+			document.documentElement.classList.add("lh-electron");
+		}
+
 		const stored = localStorage.getItem(STORAGE_KEY);
 		// Default: open (first run introduces the sidebar).
 		setOpen(stored === null ? true : stored === "1");
@@ -74,8 +84,8 @@ export function SidebarToggle() {
 	return (
 		<span
 			className={cn(
-				"sidebar-motion relative flex h-9 shrink-0 overflow-hidden duration-200",
-				open ? "w-0 -mr-3" : "w-9 mr-0",
+				"sidebar-motion lh-no-drag relative flex h-9 shrink-0 overflow-hidden duration-200",
+				open ? "w-0 -mr-3" : "w-9 mr-0 lh-closed-toggle",
 			)}
 		>
 			<Button
@@ -245,12 +255,29 @@ function SessionsSidebar() {
 			aria-hidden={!open}
 		>
 			<div className="flex h-full w-72 flex-col border-r bg-background">
-				{/* LH wordmark — the owner's header; close toggle sits at the edge. */}
-				<div className="flex items-center justify-between px-4 py-3">
-					<Link href="/" className="text-sm font-bold uppercase tracking-widest hover:opacity-80">
-						LH
+				{/* LH wordmark — the owner's header; close toggle sits at the edge.
+				    Merged chrome (2026-09-17): in Electron this band is the
+				    window's drag surface and starts after the traffic lights
+				    (.lh-lights-gutter); in the browser those classes are inert. */}
+				<div className="lh-drag lh-lights-gutter flex items-center justify-between px-4 py-3">
+					{/* The owner's mark (2026-09-17) replaces the "LH" text — still the
+					    home link, still vertically centered by the band's items-center.
+					    The 92px .lh-lights-gutter keeps it clear of the traffic lights
+					    with the lights' own edge-inset as the gap. */}
+					<Link
+						href="/"
+						aria-label="Home"
+						className="lh-no-drag shrink-0 rounded-md transition-opacity hover:opacity-80"
+					>
+						<LhMark className="size-6" />
 					</Link>
-					<Button variant="ghost" size="icon" aria-label="Close sidebar" onClick={toggle}>
+					<Button
+						variant="ghost"
+						size="icon"
+						aria-label="Close sidebar"
+						onClick={toggle}
+						className="lh-no-drag"
+					>
 						<PanelLeftCloseIcon className="size-4" />
 					</Button>
 				</div>
diff --git a/electron/main.cjs b/electron/main.cjs
index c0979d6..ad9d962 100644
--- a/electron/main.cjs
+++ b/electron/main.cjs
@@ -42,6 +42,14 @@ function serverEntry() {
 }
 
 // ─── Single instance: two instances would fight over the data dir ─────────
+// Dev shell (LH_DEV_URL) runs BESIDE the packaged app, not instead of it:
+// its own userData so (a) the single-instance lock — checked below — doesn't
+// silently kill it, and (b) it never reads/writes the real app's
+// localStorage, auth.json, or logs. Must run before the lock check.
+if (process.env.LH_DEV_URL) {
+	app.setPath("userData", `${app.getPath("userData")}-dev`);
+}
+
 if (!app.requestSingleInstanceLock()) {
 	app.quit();
 } else {
@@ -176,6 +184,14 @@ function createWindow(url) {
 		width: 1440,
 		height: 900,
 		title: PRODUCT_NAME,
+		// Merged chrome (owner, 2026-09-17): the system title bar is gone;
+		// the app's own 60px header bands ARE the title bar. The traffic
+		// lights float over the sidebar's LH wordmark band, vertically
+		// centered on its 60px line (12px circles: y 24–36), with the LH
+		// wordmark starting at x≈80 (components/sidebar.tsx gutter).
+		// Dragging comes from the renderer's .lh-drag bands (app/globals.css).
+		titleBarStyle: "hiddenInset",
+		trafficLightPosition: { x: 16, y: 24 },
 		webPreferences: {
 			contextIsolation: true,
 			sandbox: true,