Reject workspace names without manifest #1710

Author: Widthdom

src/CodeIndex/Cli/WorkspaceCommandRunner.cs

@@ -66,6 +66,9 @@ private static int Use(string[] args, bool json, JsonSerializerOptions jsonOptio
         var name = args[0];
         var manifest = WorkspaceManifestLoader.Find(Environment.CurrentDirectory);
         var useDefault = string.Equals(name, "default", StringComparison.OrdinalIgnoreCase);
+        if (manifest == null && !useDefault)
+            return CommandErrorWriter.WriteJsonOrHuman(json, jsonOptions, "workspace manifest was not found.", CommandExitCodes.UsageError, "run `cdidx workspace use <name>` from a manifest member or pass `default`.");
+
         var member = useDefault
             ? null
             : manifest?.Members.FirstOrDefault(m => string.Equals(Path.GetFileName(m.Path), name, StringComparison.OrdinalIgnoreCase));

tests/CodeIndex.Tests/WorkspaceCommandRunnerTests.cs

@@ -189,6 +189,38 @@ public void WorkspaceUse_RejectsUnknownManifestMember()
         }
     }
 
+    [Fact]
+    public void WorkspaceUse_RejectsNamedWorkspaceWithoutManifest()
+    {
+        var root = TestProjectHelper.CreateTempProject("cdidx_workspace_use_no_manifest");
+        var configHome = TestProjectHelper.CreateTempProject("cdidx_workspace_use_no_manifest_config");
+        try
+        {
+            using var env = EnvironmentVariableScope.Capture("XDG_CONFIG_HOME");
+            Environment.SetEnvironmentVariable("XDG_CONFIG_HOME", configHome);
+
+            var previous = Environment.CurrentDirectory;
+            try
+            {
+                Environment.CurrentDirectory = root;
+                var (exitCode, _, stderr) = ConsoleCapture.Capture(() => WorkspaceCommandRunner.Run(["use", "typo"], _jsonOptions));
+
+                Assert.Equal(CommandExitCodes.UsageError, exitCode);
+                Assert.Contains("workspace manifest was not found", stderr);
+                Assert.False(File.Exists(ActiveWorkspace.StatePath));
+            }
+            finally
+            {
+                Environment.CurrentDirectory = previous;
+            }
+        }
+        finally
+        {
+            TestProjectHelper.DeleteDirectory(root);
+            TestProjectHelper.DeleteDirectory(configHome);
+        }
+    }
+
     [Fact]
     public void WorkspaceUseDefault_DoesNotSelectFirstManifestMember()
     {