feat: add FeatureInstallPrompt component for uninstalled AI tool pages

Show an install prompt instead of the normal tool UI when an AI feature
bundle is not installed. Admins see a one-click install button with SSE
progress tracking and polling fallback; non-admins see a message to
contact their administrator.

apps/web/src/components/features/feature-install-prompt.tsx

@@ -0,0 +1,192 @@
+import type { FeatureBundleState } from "@ashim/shared";
+import { AlertCircle, Download, Loader2, RotateCcw } from "lucide-react";
+import { useEffect, useRef, useState } from "react";
+import { apiPost } from "@/lib/api";
+import { useFeaturesStore } from "@/stores/features-store";
+
+interface FeatureInstallPromptProps {
+  bundle: FeatureBundleState;
+  isAdmin: boolean;
+}
+
+interface ProgressState {
+  percent: number;
+  stage: string;
+}
+
+export function FeatureInstallPrompt({ bundle, isAdmin }: FeatureInstallPromptProps) {
+  const [installing, setInstalling] = useState(false);
+  const [progress, setProgress] = useState<ProgressState | null>(null);
+  const [error, setError] = useState<string | null>(null);
+  const eventSourceRef = useRef<EventSource | null>(null);
+  const pollingRef = useRef<ReturnType<typeof setInterval> | null>(null);
+  const refresh = useFeaturesStore((s) => s.refresh);
+
+  // If bundle is already installing on mount, show progress state immediately
+  useEffect(() => {
+    if (bundle.status === "installing") {
+      setInstalling(true);
+      setProgress(bundle.progress ?? { percent: 0, stage: "Installing..." });
+    }
+  }, [bundle.status, bundle.progress]);
+
+  // Cleanup on unmount
+  useEffect(() => {
+    return () => {
+      eventSourceRef.current?.close();
+      if (pollingRef.current) clearInterval(pollingRef.current);
+    };
+  }, []);
+
+  function startPollingFallback() {
+    if (pollingRef.current) return;
+    pollingRef.current = setInterval(async () => {
+      try {
+        await refresh();
+        const updated = useFeaturesStore.getState().bundles.find((b) => b.id === bundle.id);
+        if (!updated || updated.status !== "installing") {
+          if (pollingRef.current) clearInterval(pollingRef.current);
+          pollingRef.current = null;
+          setInstalling(false);
+          if (updated?.status === "error") {
+            setError(updated.error ?? "Installation failed");
+          } else {
+            setProgress(null);
+          }
+        } else if (updated.progress) {
+          setProgress(updated.progress);
+        }
+      } catch {
+        // ignore polling errors
+      }
+    }, 3000);
+  }
+
+  function listenToProgress(jobId: string) {
+    const es = new EventSource(`/api/v1/jobs/${jobId}/progress`);
+    eventSourceRef.current = es;
+
+    es.onmessage = (event) => {
+      try {
+        const data = JSON.parse(event.data) as {
+          phase: string;
+          percent: number;
+          stage: string;
+          error?: string;
+        };
+
+        if (data.phase === "complete") {
+          es.close();
+          eventSourceRef.current = null;
+          setInstalling(false);
+          setProgress(null);
+          refresh();
+          return;
+        }
+
+        if (data.phase === "failed") {
+          es.close();
+          eventSourceRef.current = null;
+          setInstalling(false);
+          setError(data.error ?? "Installation failed");
+          return;
+        }
+
+        setProgress({ percent: data.percent, stage: data.stage });
+      } catch {
+        // ignore malformed messages
+      }
+    };
+
+    es.onerror = () => {
+      es.close();
+      eventSourceRef.current = null;
+      startPollingFallback();
+    };
+  }
+
+  async function handleInstall() {
+    setInstalling(true);
+    setError(null);
+    setProgress({ percent: 0, stage: "Starting installation..." });
+
+    try {
+      const result = await apiPost<{ jobId: string }>(`/v1/admin/features/${bundle.id}/install`);
+      listenToProgress(result.jobId);
+    } catch (err) {
+      setInstalling(false);
+      setError(err instanceof Error ? err.message : "Failed to start installation");
+    }
+  }
+
+  // Non-admin: show "not enabled" message
+  if (!isAdmin) {
+    return (
+      <div className="flex flex-col items-center justify-center h-full gap-4 text-center px-4">
+        <Download className="h-16 w-16 text-muted-foreground" />
+        <h2 className="text-xl font-semibold text-foreground">Feature Not Enabled</h2>
+        <p className="text-muted-foreground max-w-md">
+          This feature is not enabled. Ask your administrator to enable it in Settings.
+        </p>
+      </div>
+    );
+  }
+
+  // Admin: show install prompt
+  return (
+    <div className="flex flex-col items-center justify-center h-full gap-6 text-center px-4">
+      <Download className="h-16 w-16 text-muted-foreground" />
+      <div className="space-y-2">
+        <h2 className="text-xl font-semibold text-foreground">{bundle.name}</h2>
+        <p className="text-muted-foreground max-w-md">{bundle.description}</p>
+        <p className="text-sm text-muted-foreground">
+          This feature requires an additional download (~{bundle.estimatedSize})
+        </p>
+      </div>
+
+      {/* Error banner */}
+      {error && (
+        <div className="flex items-center gap-2 bg-destructive/10 text-destructive rounded-lg px-4 py-3 max-w-md w-full">
+          <AlertCircle className="h-4 w-4 shrink-0" />
+          <span className="text-sm flex-1 text-left">{error}</span>
+          <button
+            type="button"
+            onClick={handleInstall}
+            className="flex items-center gap-1 text-sm font-medium hover:opacity-80"
+          >
+            <RotateCcw className="h-3.5 w-3.5" />
+            Retry
+          </button>
+        </div>
+      )}
+
+      {/* Progress bar */}
+      {installing && progress && (
+        <div className="w-full max-w-md space-y-2">
+          <div className="h-2 bg-muted rounded-full overflow-hidden">
+            <div
+              className="h-full bg-primary rounded-full transition-all duration-300"
+              style={{ width: `${progress.percent}%` }}
+            />
+          </div>
+          <div className="flex items-center justify-center gap-2 text-sm text-muted-foreground">
+            <Loader2 className="h-4 w-4 animate-spin" />
+            <span>{progress.stage}</span>
+          </div>
+        </div>
+      )}
+
+      {/* Install button (hidden when installing or showing error) */}
+      {!installing && !error && (
+        <button
+          type="button"
+          onClick={handleInstall}
+          disabled={installing || bundle.status === "installing"}
+          className="px-6 py-2.5 bg-primary text-primary-foreground rounded-lg hover:bg-primary/90 disabled:opacity-50 font-medium"
+        >
+          Enable {bundle.name}
+        </button>
+      )}
+    </div>
+  );
+}

apps/web/src/pages/tool-page.tsx

@@ -1,4 +1,4 @@
-import { TOOLS } from "@ashim/shared";
+import { PYTHON_SIDECAR_TOOLS, TOOLS } from "@ashim/shared";
 import {
   CheckCircle2,
   ChevronLeft,
@@ -16,15 +16,18 @@ import { type BgPreviewState, ImageViewer } from "@/components/common/image-view
 import { ReviewPanel } from "@/components/common/review-panel";
 import { SideBySideComparison } from "@/components/common/side-by-side-comparison";
 import { ThumbnailStrip } from "@/components/common/thumbnail-strip";
+import { FeatureInstallPrompt } from "@/components/features/feature-install-prompt";
 import { AppLayout } from "@/components/layout/app-layout";
 import { CropCanvas } from "@/components/tools/crop-canvas";
 import type { EraserCanvasRef } from "@/components/tools/eraser-canvas";
 import { EraserCanvas } from "@/components/tools/eraser-canvas";
 import type { PreviewTransform } from "@/components/tools/rotate-settings";
+import { useAuth } from "@/hooks/use-auth";
 import { useMobile } from "@/hooks/use-mobile";
 import { formatFileSize } from "@/lib/download";
 import { ICON_MAP } from "@/lib/icon-map";
 import { getToolRegistryEntry } from "@/lib/tool-registry";
+import { useFeaturesStore } from "@/stores/features-store";
 import { useFileStore } from "@/stores/file-store";
 
 /** Formats that browsers can render in <img> tags. */
@@ -106,6 +109,13 @@ export function ToolPage() {
     () => (toolId ? getToolRegistryEntry(toolId) : undefined),
     [toolId],
   );
+  const isAiTool = toolId ? (PYTHON_SIDECAR_TOOLS as readonly string[]).includes(toolId) : false;
+  const getBundleForTool = useFeaturesStore((s) => s.getBundleForTool);
+  const isToolInstalled = useFeaturesStore((s) => s.isToolInstalled);
+  const featureBundle = toolId ? getBundleForTool(toolId) : null;
+  const toolInstalled = toolId ? isToolInstalled(toolId) : true;
+  const { hasPermission } = useAuth();
+  const isAdmin = hasPermission("settings:write");
   const {
     files,
     entries,
@@ -234,6 +244,14 @@ export function ToolPage() {
     );
   }
 
+  if (isAiTool && !toolInstalled && featureBundle) {
+    return (
+      <AppLayout>
+        <FeatureInstallPrompt bundle={featureBundle} isAdmin={isAdmin} />
+      </AppLayout>
+    );
+  }
+
   const IconComponent =
     (ICON_MAP[tool.icon] as React.ComponentType<{ className?: string }>) ?? FileImage;