feat: show workspace health error alert above agents in WorkspacePage (#19400)

closes #19338 

<img width="1840" height="1191" alt="image"
src="https://github.com/user-attachments/assets/eeefda13-88d1-4a26-ba57-9749abda3f17"
/>

site/src/pages/WorkspacePage/Workspace.stories.tsx

@@ -9,6 +9,7 @@ import type { ProvisionerJobLog } from "api/typesGenerated";
 import { action } from "storybook/actions";
 import type { WorkspacePermissions } from "../../modules/workspaces/permissions";
 import { Workspace } from "./Workspace";
+import { defaultPermissions } from "./WorkspaceNotifications/WorkspaceNotifications.stories";
 
 // Helper function to create timestamps easily - Copied from AppStatuses.stories.tsx
 const createTimestamp = (
@@ -349,6 +350,23 @@ export const Stopping: Story = {
 	},
 };
 
+export const Unhealthy: Story = {
+	args: {
+		...Running.args,
+		workspace: Mocks.MockUnhealthyWorkspace,
+	},
+};
+
+export const UnhealthyWithoutUpdatePermission: Story = {
+	args: {
+		...Unhealthy.args,
+		permissions: {
+			...defaultPermissions,
+			updateWorkspace: false,
+		},
+	},
+};
+
 export const FailedWithLogs: Story = {
 	args: {
 		...Running.args,

site/src/pages/WorkspacePage/Workspace.tsx

@@ -21,6 +21,8 @@ import {
 	WorkspaceBuildProgress,
 } from "./WorkspaceBuildProgress";
 import { WorkspaceDeletedBanner } from "./WorkspaceDeletedBanner";
+import { NotificationActionButton } from "./WorkspaceNotifications/Notifications";
+import { findTroubleshootingURL } from "./WorkspaceNotifications/WorkspaceNotifications";
 import { WorkspaceTopbar } from "./WorkspaceTopbar";
 
 interface WorkspaceProps {
@@ -97,6 +99,8 @@ export const Workspace: FC<WorkspaceProps> = ({
 		(workspace.latest_build.matched_provisioners?.available ?? 1) > 0;
 	const shouldShowProvisionerAlert =
 		workspacePending && !haveBuildLogs && !provisionersHealthy && !isRestarting;
+	const troubleshootingURL = findTroubleshootingURL(workspace.latest_build);
+	const hasActions = permissions.updateWorkspace || troubleshootingURL;
 
 	return (
 		<div className="flex flex-col flex-1 min-h-0">
@@ -194,6 +198,41 @@ export const Workspace: FC<WorkspaceProps> = ({
 							</Alert>
 						)}
 
+						{!workspace.health.healthy && (
+							<Alert severity="warning">
+								<AlertTitle>Workspace is unhealthy</AlertTitle>
+								<AlertDetail>
+									<p>
+										Your workspace is running but{" "}
+										{workspace.health.failing_agents.length > 1
+											? `${workspace.health.failing_agents.length} agents are unhealthy`
+											: "1 agent is unhealthy"}
+										.
+									</p>
+									{hasActions && (
+										<div className="flex items-center gap-2">
+											{permissions.updateWorkspace && (
+												<NotificationActionButton
+													onClick={() => handleRestart()}
+												>
+													Restart
+												</NotificationActionButton>
+											)}
+											{troubleshootingURL && (
+												<NotificationActionButton
+													onClick={() =>
+														window.open(troubleshootingURL, "_blank")
+													}
+												>
+													Troubleshooting
+												</NotificationActionButton>
+											)}
+										</div>
+									)}
+								</AlertDetail>
+							</Alert>
+						)}
+
 						{transitionStats !== undefined && (
 							<WorkspaceBuildProgress
 								workspace={workspace}

site/src/pages/WorkspacePage/WorkspaceNotifications/WorkspaceNotifications.stories.tsx

@@ -12,7 +12,7 @@ import type { WorkspacePermissions } from "modules/workspaces/permissions";
 import { expect, userEvent, waitFor, within } from "storybook/test";
 import { WorkspaceNotifications } from "./WorkspaceNotifications";
 
-const defaultPermissions: WorkspacePermissions = {
+export const defaultPermissions: WorkspacePermissions = {
 	readWorkspace: true,
 	updateWorkspaceVersion: true,
 	updateWorkspace: true,

site/src/pages/WorkspacePage/WorkspaceNotifications/WorkspaceNotifications.tsx

@@ -275,7 +275,7 @@ const styles = {
 	},
 } satisfies Record<string, Interpolation<Theme>>;
 
-const findTroubleshootingURL = (
+export const findTroubleshootingURL = (
 	workspaceBuild: WorkspaceBuild,
 ): string | undefined => {
 	for (const resource of workspaceBuild.resources) {

site/src/testHelpers/entities.ts

@@ -994,6 +994,15 @@ export const MockWorkspaceSubAgent: TypesGen.WorkspaceAgent = {
 	],
 };
 
+const MockWorkspaceUnhealthyAgent: TypesGen.WorkspaceAgent = {
+	...MockWorkspaceAgent,
+	id: "test-workspace-unhealthy-agent",
+	name: "a-workspace-unhealthy-agent",
+	status: "timeout",
+	lifecycle_state: "start_error",
+	health: { healthy: false },
+};
+
 export const MockWorkspaceAppStatus: TypesGen.WorkspaceAppStatus = {
 	id: "test-app-status",
 	created_at: "2022-05-17T17:39:01.382927298Z",
@@ -1445,6 +1454,20 @@ export const MockStoppingWorkspace: TypesGen.Workspace = {
 		status: "stopping",
 	},
 };
+export const MockUnhealthyWorkspace: TypesGen.Workspace = {
+	...MockWorkspace,
+	id: "test-unhealthy-workspace",
+	health: {
+		healthy: false,
+		failing_agents: [MockWorkspaceUnhealthyAgent.id],
+	},
+	latest_build: {
+		...MockWorkspace.latest_build,
+		resources: [
+			{ ...MockWorkspaceResource, agents: [MockWorkspaceUnhealthyAgent] },
+		],
+	},
+};
 export const MockStartingWorkspace: TypesGen.Workspace = {
 	...MockWorkspace,
 	id: "test-starting-workspace",