fix: prevent cumulative terminal shrinkage in fullscreen mode

When switching terminal sessions in fullscreen mode, the viewport
shrank cumulatively because .terminal-wrapper uses
grid-template-rows: auto 1fr. With showControls=false, the single
child (.terminal-container) landed in the auto track instead of 1fr,
creating a feedback loop with xterm fit().

- Add .terminal-wrapper.no-controls with grid-template-rows: 1fr
  so the container fills the wrapper when the header is hidden.
- Apply no-controls class in TerminalComponent when showControls=false.
- Replace setTimeout(50) with double requestAnimationFrame in
  TerminalPage for more reliable fit() timing after tab switches.

Quality gates: tsc --noEmit (clean), pytest (208 passed, 6 pre-existing)

apps/web/src/components/terminal.tsx

@@ -568,7 +568,7 @@ export const TerminalComponent = React.forwardRef<TerminalRef, TerminalProps>(
 		};
 
 		return (
-			<div className={`terminal-wrapper ${isMobile ? "mobile" : ""}`}>
+			<div className={`terminal-wrapper ${isMobile ? "mobile" : ""} ${!showControls ? "no-controls" : ""}`}>
 				{showControls && (
 					<div className="terminal-header">
 						<div className="terminal-header-left">

apps/web/src/pages/terminal.tsx

@@ -17,7 +17,12 @@ const SESSIONS_TO_INFO = (sessions: TerminalSession[]): TerminalSessionInfo[] =>
 		status: s.status as TerminalSessionInfo["status"],
 	}));
 
-type TerminalStatus = "connecting" | "connected" | "disconnected" | "error" | "resetting";
+type TerminalStatus =
+	| "connecting"
+	| "connected"
+	| "disconnected"
+	| "error"
+	| "resetting";
 
 export const TerminalPage: React.FC = () => {
 	const { instanceId } = useParams<{
@@ -30,7 +35,9 @@ export const TerminalPage: React.FC = () => {
 	const headerAutoHide = useAutoHide({ timeout: 3000, enabled: isMobile });
 
 	// Track terminal status and callbacks for unified fullscreen header
-	const [terminalStatuses, setTerminalStatuses] = useState<Record<string, TerminalStatus>>({});
+	const [terminalStatuses, setTerminalStatuses] = useState<
+		Record<string, TerminalStatus>
+	>({});
 	const changeFontSizeRef = useRef<((delta: number) => void) | null>(null);
 	const [showResetConfirm, setShowResetConfirm] = useState(false);
 
@@ -73,12 +80,19 @@ export const TerminalPage: React.FC = () => {
 	useEffect(() => {
 		if (activeSessionId && terminalRefs.current[activeSessionId]) {
 			const ref = terminalRefs.current[activeSessionId];
-			// Small delay to allow display:block to apply
-			const timer = setTimeout(() => {
-				ref.current?.fit();
-				ref.current?.focus();
-			}, 50);
-			return () => clearTimeout(timer);
+			// Double rAF ensures layout has settled after the display:block switch
+			let raf1 = 0;
+			let raf2 = 0;
+			raf1 = requestAnimationFrame(() => {
+				raf2 = requestAnimationFrame(() => {
+					ref.current?.fit();
+					ref.current?.focus();
+				});
+			});
+			return () => {
+				cancelAnimationFrame(raf1);
+				cancelAnimationFrame(raf2);
+			};
 		}
 	}, [activeSessionId]);
 
@@ -192,7 +206,10 @@ export const TerminalPage: React.FC = () => {
 			_focusInput: () => void,
 			changeFontSize: (delta: number) => void,
 		) => {
-			setTerminalStatuses((prev) => ({ ...prev, [activeSessionId ?? "default"]: status }));
+			setTerminalStatuses((prev) => ({
+				...prev,
+				[activeSessionId ?? "default"]: status,
+			}));
 			changeFontSizeRef.current = changeFontSize;
 		},
 		[activeSessionId],

apps/web/src/styles.css

@@ -2562,6 +2562,13 @@ a.nav-item,
 	background: #1e1e1e;
 }
 
+/* When controls are hidden (fullscreen), only the container is in flow;
+   force it into the 1fr track so it fills the wrapper instead of landing
+   in the auto track and shrinking on each fit(). */
+.terminal-wrapper.no-controls {
+	grid-template-rows: 1fr;
+}
+
 .terminal-header {
 	display: flex;
 	justify-content: space-between;

openspec/changes/terminal-fullscreen-unified-header/.openspec.yaml

@@ -1,6 +1,6 @@
 name: terminal-fullscreen-unified-header
-status: in-progress
-phase: apply
+status: completed
+phase: verify
 type: bugfix
 description: Fix terminal fullscreen mode where session switcher overlays terminal controls. Combine both elements into a single unified header visible at all times.
 created_at: 2026-05-28