fix(web): avoid reusing unrelated html artifact groups

apps/web/src/components/ProjectView.tsx

@@ -1144,22 +1144,26 @@ export function ProjectView({
       // keeping index.html stable for multi-page HTML artifacts.
       const currentProjectFiles = projectFilesSnapshot ?? projectFilesRef.current;
       const existing = new Set(currentProjectFiles.map((f) => f.name));
+      const canOverwriteExistingEntry = canOverwriteHtmlArtifactEntry({
+        baseName,
+        ext,
+        projectFiles: currentProjectFiles,
+        savedArtifactName: savedArtifactRef.current,
+        artifactIdentifier: art.identifier,
+      });
       const fileName = resolveHtmlArtifactFileName({
         baseName,
         ext,
         existingFileNames: existing,
         savedArtifactName: savedArtifactRef.current,
-        canOverwriteExistingEntry: canOverwriteHtmlArtifactEntry({
-          baseName,
-          ext,
-          projectFiles: currentProjectFiles,
-          savedArtifactName: savedArtifactRef.current,
-          artifactIdentifier: art.identifier,
-        }),
+        canOverwriteExistingEntry,
       });
       const artifactGroupIdentifier =
         ext === '.html'
-          ? htmlArtifactGroupIdentifierFor(art, currentProjectFiles, fileName)
+          ? htmlArtifactGroupIdentifierFor(art, currentProjectFiles, fileName, {
+              canReuseExistingGroup:
+                canOverwriteExistingEntry || savedArtifactRef.current === fileName,
+            })
           : undefined;
       const html =
         ext === '.html'
@@ -4640,23 +4644,40 @@ function htmlArtifactGroupIdentifierFor(
   art: Artifact,
   projectFiles: ProjectFile[],
   fileName: string,
+  options: { canReuseExistingGroup: boolean },
 ): string {
-  const identifier = normalizeArtifactGroupSegment(art.identifier);
-  if (identifier) {
-    const existingGroup = projectFiles
-      .filter((file) => {
-        return normalizeArtifactGroupSegment(file.artifactManifest?.metadata?.identifier) === identifier;
-      })
-      .sort((a, b) => b.mtime - a.mtime)
-      .map((file) => file.artifactManifest?.metadata?.artifactGroupIdentifier)
-      .find((value): value is string => {
-        return typeof value === 'string' && normalizeArtifactGroupSegment(value).length > 0;
-      });
-    if (existingGroup) return existingGroup;
+  const existingFile = projectFiles.find((file) => file.name === fileName || file.path === fileName);
+  const existingFileGroup = existingArtifactGroupIdentifier(
+    existingFile?.artifactManifest?.metadata?.artifactGroupIdentifier,
+  );
+  if (options.canReuseExistingGroup && existingFileGroup) {
+    return existingFileGroup;
   }
+
+  if (options.canReuseExistingGroup) {
+    const identifier = normalizeArtifactGroupSegment(art.identifier);
+    if (identifier) {
+      const existingGroup = projectFiles
+        .filter((file) => {
+          return normalizeArtifactGroupSegment(file.artifactManifest?.metadata?.identifier) === identifier;
+        })
+        .sort((a, b) => b.mtime - a.mtime)
+        .map((file) => file.artifactManifest?.metadata?.artifactGroupIdentifier)
+        .find((value): value is string => {
+          return typeof value === 'string' && normalizeArtifactGroupSegment(value).length > 0;
+        });
+      if (existingGroup) return existingGroup;
+    }
+  }
+
   return `html-artifact:${fileName}`;
 }
 
+function existingArtifactGroupIdentifier(value: unknown): string | null {
+  if (typeof value !== 'string') return null;
+  return normalizeArtifactGroupSegment(value).length > 0 ? value : null;
+}
+
 function normalizeArtifactGroupSegment(value: unknown): string {
   if (typeof value !== 'string') return '';
   return value

apps/web/tests/components/ProjectView.api-empty-response.test.tsx

@@ -643,6 +643,54 @@ describe('ProjectView API empty response handling', () => {
     expect(content).toContain('href="about-2.html"');
   });
 
+  it('starts a fresh group when a new index artifact is relocated away from an existing owner', async () => {
+    mockedFetchProjectFiles.mockResolvedValue([
+      htmlProjectFile('index.html', 10, {
+        artifactIdentifier: 'Index',
+        artifactGroupIdentifier: 'site-a',
+      }),
+      htmlProjectFile('about.html', 20, {
+        artifactIdentifier: 'about',
+        artifactGroupIdentifier: 'site-a',
+      }),
+      htmlProjectFile('about-2.html', 40, {
+        artifactIdentifier: 'about',
+        artifactGroupIdentifier: 'site-a',
+      }),
+    ] as never);
+    mockedWriteProjectTextFile.mockResolvedValue(htmlProjectFile('index-2.html', 50) as never);
+    const artifact =
+      '<artifact identifier="index" type="text/html" title="Multipage Site">' +
+      '<!doctype html><html><head><title>Home</title></head><body>' +
+      '<main><h1>Home</h1><a href="about.html">About</a></main>' +
+      '</body></html>' +
+      '</artifact>';
+    mockedStreamMessage.mockImplementation(async (
+      _cfg: AppConfig,
+      _system: string,
+      _history: ChatMessage[],
+      _signal: AbortSignal,
+      handlers: StreamHandlers,
+    ) => {
+      handlers.onDelta(artifact);
+      handlers.onDone('');
+    });
+    renderProjectView();
+
+    await sendTestPrompt();
+
+    await waitFor(() => {
+      expect(mockedWriteProjectTextFile).toHaveBeenCalled();
+    });
+    const [, fileName, content, options] = mockedWriteProjectTextFile.mock.calls.at(-1) ?? [];
+    expect(fileName).toBe('index-2.html');
+    expect(content).toContain('href="about.html"');
+    expect(content).not.toContain('href="about-2.html"');
+    expect(options?.artifactManifest?.metadata?.artifactGroupIdentifier).toBe(
+      'html-artifact:index-2.html',
+    );
+  });
+
   it('rewrites child links for legacy multipage artifacts without group metadata', async () => {
     mockedFetchProjectFiles.mockResolvedValue([
       htmlProjectFile('index.html', 10, { artifactIdentifier: 'index' }),