diff --git a/frontend/src/renderer/components/SessionInspector.test.tsx b/frontend/src/renderer/components/SessionInspector.test.tsx
index a5d654777..77c0bd67a 100644
--- a/frontend/src/renderer/components/SessionInspector.test.tsx
+++ b/frontend/src/renderer/components/SessionInspector.test.tsx
@@ -173,7 +173,7 @@ describe("SessionInspector Activity section", () => {
 	it.each([
 		["idle", "Idle"],
 		["active", "Working"],
-		["waiting_input", "Input needed"],
+		["waiting_input", "Input Needed"],
 		["exited", "Exited"],
 	] as const)("renders %s from raw session activity", (state, label) => {
 		renderWithQuery(
@@ -188,6 +188,40 @@ describe("SessionInspector Activity section", () => {
 		expect(activitySection().getByText(label)).toBeInTheDocument();
 	});
 
+	it("renders unknown activity as unavailable instead of leaking the internal enum", () => {
+		renderWithQuery(
+			<SessionInspector
+				session={session([], {
+					status: "working",
+					activity: { state: "unknown", lastActivityAt: "2026-06-15T10:00:00Z" },
+				})}
+			/>,
+		);
+
+		expect(activitySection().getByText("Activity Unavailable")).toBeInTheDocument();
+		expect(activitySection().queryByText("Unknown")).not.toBeInTheDocument();
+	});
+
+	it("falls back to unavailable when no activity has been reported", () => {
+		renderWithQuery(<SessionInspector session={session([], { status: "working" })} />);
+
+		expect(activitySection().getByText("Activity Unavailable")).toBeInTheDocument();
+	});
+
+	it("keeps the last known activity visible when the daemon reports no signal", () => {
+		renderWithQuery(
+			<SessionInspector
+				session={session([], {
+					status: "no_signal",
+					activity: { state: "idle", lastActivityAt: "2026-06-15T10:00:00Z" },
+				})}
+			/>,
+		);
+
+		const activityRow = activitySection().getByText("Idle").closest(".inspector-timeline__ev") as HTMLElement;
+		expect(within(activityRow).getByText("No Signal")).toBeInTheDocument();
+	});
+
 	it("does not derive the Activity label from PR-oriented session status", () => {
 		renderWithQuery(
 			<SessionInspector
@@ -199,12 +233,12 @@ describe("SessionInspector Activity section", () => {
 		);
 
 		expect(activitySection().getByText("Idle")).toBeInTheDocument();
-		expect(activitySection().queryByText("Input needed")).not.toBeInTheDocument();
+		expect(activitySection().queryByText("Input Needed")).not.toBeInTheDocument();
 	});
 
 	it.each([
-		["ci_failed", "CI failed"],
-		["changes_requested", "Changes requested"],
+		["ci_failed", "CI Failed"],
+		["changes_requested", "Changes Requested"],
 	] as const)("renders %s as an SCM state in the current Activity row", (status, label) => {
 		renderWithQuery(
 			<SessionInspector
@@ -265,8 +299,8 @@ describe("SessionInspector Activity section", () => {
 		expect(activitySection().getByText("Opened")).toBeInTheDocument();
 		expect(activitySection().getByText("PR #7")).toBeInTheDocument();
 		const activityRow = activitySection().getByText("Idle").closest(".inspector-timeline__ev") as HTMLElement;
-		expect(within(activityRow).getByText("CI failed")).toBeInTheDocument();
-		expect(within(activityRow).getByText("Changes requested")).toBeInTheDocument();
+		expect(within(activityRow).getByText("CI Failed")).toBeInTheDocument();
+		expect(within(activityRow).getByText("Changes Requested")).toBeInTheDocument();
 	});
 
 	it("orders timeline milestones around the combined current state row", () => {
diff --git a/frontend/src/renderer/components/SessionInspector.tsx b/frontend/src/renderer/components/SessionInspector.tsx
index 485ea448d..192c2677c 100644
--- a/frontend/src/renderer/components/SessionInspector.tsx
+++ b/frontend/src/renderer/components/SessionInspector.tsx
@@ -298,6 +298,11 @@ function ActivityTimeline({ session }: { session: WorkspaceSession }) {
 				<span className="inspector-timeline__badge">
 					<InspectorActivityPill state={session.activity?.state ?? "unknown"} />
 				</span>
+				{session.status === "no_signal" ? (
+					<span className="inspector-timeline__badge">
+						<TimelinePill {...ACTIVITY_WARNING_PILL.no_signal} />
+					</span>
+				) : null}
 				{scmTimelineStates(session).map((state) => (
 					<span key={state} className="inspector-timeline__badge">
 						<InspectorScmPill state={state} />
@@ -352,16 +357,20 @@ function ActivityTimeline({ session }: { session: WorkspaceSession }) {
 const ACTIVITY_PILL: Record<SessionActivityState, { label: string; tone: string; breathe: boolean }> = {
 	active: { label: "Working", tone: "var(--orange)", breathe: true },
 	idle: { label: "Idle", tone: "var(--fg-muted)", breathe: false },
-	waiting_input: { label: "Input needed", tone: "var(--amber)", breathe: false },
+	waiting_input: { label: "Input Needed", tone: "var(--amber)", breathe: false },
 	exited: { label: "Exited", tone: "var(--fg-muted)", breathe: false },
-	unknown: { label: "Unknown", tone: "var(--fg-muted)", breathe: false },
+	unknown: { label: "Activity Unavailable", tone: "var(--fg-muted)", breathe: false },
+};
+
+const ACTIVITY_WARNING_PILL: Record<"no_signal", { label: string; tone: string; breathe: boolean }> = {
+	no_signal: { label: "No Signal", tone: "var(--fg-muted)", breathe: false },
 };
 
 type ScmTimelineState = "ci_failed" | "changes_requested" | "conflict";
 
 const SCM_PILL: Record<ScmTimelineState, { label: string; tone: string; breathe: boolean }> = {
-	ci_failed: { label: "CI failed", tone: "var(--red)", breathe: false },
-	changes_requested: { label: "Changes requested", tone: "var(--amber)", breathe: false },
+	ci_failed: { label: "CI Failed", tone: "var(--red)", breathe: false },
+	changes_requested: { label: "Changes Requested", tone: "var(--amber)", breathe: false },
 	conflict: { label: "Conflict", tone: "var(--red)", breathe: false },
 };