Exclude default shared workspaces from tab

Co-Authored-By: Paperclip <noreply@paperclip.ing>

ui/src/lib/project-workspaces-tab.test.ts

@@ -195,4 +195,31 @@ describe("buildProjectWorkspaceSummaries", () => {
     expect(summaries).toHaveLength(1);
     expect(summaries[0]?.key).toBe("execution:exec-2");
   });
+
+  it("excludes issues that only use the default shared workspace", () => {
+    const summaries = buildProjectWorkspaceSummaries({
+      project,
+      issues: [
+        createIssue({
+          id: "issue-default-shared",
+          projectWorkspaceId: primaryWorkspace.id,
+          executionWorkspaceId: "exec-shared-default",
+          updatedAt: new Date("2026-03-26T12:00:00Z"),
+        }),
+      ],
+      executionWorkspaces: [
+        createExecutionWorkspace({
+          id: "exec-shared-default",
+          mode: "shared_workspace",
+          strategyType: "project_primary",
+          projectWorkspaceId: primaryWorkspace.id,
+          branchName: null,
+          baseRef: null,
+          providerType: "local_fs",
+        }),
+      ],
+    });
+
+    expect(summaries).toHaveLength(0);
+  });
 });

ui/src/lib/project-workspaces-tab.ts

@@ -36,6 +36,16 @@ function primaryWorkspaceId(project: ProjectWorkspaceLike): string | null {
     ?? null;
 }
 
+function isDefaultSharedExecutionWorkspace(input: {
+  executionWorkspace: ExecutionWorkspace;
+  issue: Issue;
+  primaryWorkspaceId: string | null;
+}) {
+  const linkedProjectWorkspaceId =
+    input.executionWorkspace.projectWorkspaceId ?? input.issue.projectWorkspaceId ?? null;
+  return input.executionWorkspace.mode === "shared_workspace" && linkedProjectWorkspaceId === input.primaryWorkspaceId;
+}
+
 export function buildProjectWorkspaceSummaries(input: {
   project: ProjectWorkspaceLike;
   issues: Issue[];
@@ -54,6 +64,11 @@ export function buildProjectWorkspaceSummaries(input: {
     if (issue.executionWorkspaceId) {
       const executionWorkspace = executionWorkspacesById.get(issue.executionWorkspaceId);
       if (!executionWorkspace) continue;
+      if (isDefaultSharedExecutionWorkspace({
+        executionWorkspace,
+        issue,
+        primaryWorkspaceId: primaryId,
+      })) continue;
 
       const existing = summaries.get(`execution:${executionWorkspace.id}`);
       const nextIssues = [...(existing?.issues ?? []), issue].sort(