openFile opens files kept by another file system (ABAP); the diff tools refuse them plainly

com.anthropic.claudecode.eclipse/src/com/anthropic/claudecode/eclipse/editor/EditorParts.java

@@ -1,6 +1,7 @@
 package com.anthropic.claudecode.eclipse.editor;
 
 import java.net.URI;
+import java.net.URISyntaxException;
 import java.util.function.Function;
 
 import org.eclipse.core.resources.IResource;
@@ -59,6 +60,46 @@ public static String pathOf(IEditorInput input) {
         return null;
     }
 
+    /**
+     * Whether {@code path} is not a path on the local disk but a URI of another file system
+     * ({@code semanticfs:/E10/...} for ABAP, a remote project's): what {@link #pathOf(IResource)}
+     * reports for a file that has no disk path. A Windows drive letter ({@code C:\x}) is not a
+     * scheme, nor is {@code file:}, which names a disk file.
+     */
+    public static boolean isNonDiskPath(String path) {
+        String scheme = schemeOf(path);
+        return scheme != null && !scheme.equalsIgnoreCase("file");
+    }
+
+    /** The URI {@code path} names when {@link #isNonDiskPath} says it is one, else null. */
+    public static URI nonDiskUriOf(String path) {
+        if (!isNonDiskPath(path)) return null;
+        try {
+            return new URI(path);
+        } catch (URISyntaxException e) {
+            return null;
+        }
+    }
+
+    /** What a tool that reads and writes by disk path says when it is handed a URI of another file system. */
+    public static String notOnDiskMessage(String path) {
+        return path + " is not a file on disk: the \"" + schemeOf(path) + "\" file system keeps it, so this tool, "
+            + "which reads and writes files by path, cannot work on it. Use the editor it is open in instead.";
+    }
+
+    /** The scheme of a URI-looking path (two or more characters, so not a drive letter), or null. */
+    private static String schemeOf(String path) {
+        if (path == null) return null;
+        int colon = path.indexOf(':');
+        if (colon < 2) return null;
+        if (!Character.isLetter(path.charAt(0))) return null;
+        for (int i = 1; i < colon; i++) {
+            char c = path.charAt(i);
+            if (!Character.isLetterOrDigit(c) && c != '+' && c != '-' && c != '.') return null;
+        }
+        return path.substring(0, colon);
+    }
+
     /**
      * The disk path of a workspace resource. One kept on a file system other than the
      * local one (ABAP's {@code semanticfs:}, a remote project) has no disk path, so its

com.anthropic.claudecode.eclipse/src/com/anthropic/claudecode/eclipse/tools/AcceptDiffTool.java

@@ -9,6 +9,7 @@
 import org.eclipse.ui.IEditorReference;
 import org.eclipse.ui.IWorkbenchPage;
 
+import com.anthropic.claudecode.eclipse.editor.EditorParts;
 import com.anthropic.claudecode.eclipse.editor.UiHelper;
 import com.anthropic.claudecode.eclipse.mcp.McpTool;
 import com.anthropic.claudecode.eclipse.mcp.McpToolResult;
@@ -48,6 +49,7 @@ public JsonObject inputSchema() {
     @Override
     public McpToolResult execute(JsonObject params) {
         String filePath = EditorUtils.requireString(params, "file_path", "filePath");
+        if (EditorParts.isNonDiskPath(filePath)) return McpToolResult.error(EditorParts.notOnDiskMessage(filePath));
 
         DiffRegistry.DiffEntry entry = DiffRegistry.getInstance().get(filePath);
         if (entry == null) {

com.anthropic.claudecode.eclipse/src/com/anthropic/claudecode/eclipse/tools/OpenDiffTool.java

@@ -38,6 +38,7 @@
 
 import com.anthropic.claudecode.eclipse.Activator;
 import com.anthropic.claudecode.eclipse.Constants;
+import com.anthropic.claudecode.eclipse.editor.EditorParts;
 import com.anthropic.claudecode.eclipse.editor.UiHelper;
 import com.anthropic.claudecode.eclipse.mcp.McpTool;
 import com.anthropic.claudecode.eclipse.mcp.McpToolResult;
@@ -99,6 +100,7 @@ public JsonObject inputSchema() {
     @Override
     public McpToolResult execute(JsonObject params) {
         String filePath = EditorUtils.requireString(params, "old_file_path", "filePath");
+        if (EditorParts.isNonDiskPath(filePath)) return McpToolResult.error(EditorParts.notOnDiskMessage(filePath));
         String newContent = EditorUtils.requireString(params, "new_file_contents", "newContent");
         String rawTabLabel = EditorUtils.getString(params, "tab_name", "tabLabel");
         String tabLabel = rawTabLabel != null ? rawTabLabel

com.anthropic.claudecode.eclipse/src/com/anthropic/claudecode/eclipse/tools/OpenFileTool.java

@@ -1,15 +1,19 @@
 package com.anthropic.claudecode.eclipse.tools;
 
+import java.net.URI;
 import java.nio.file.Path;
 
 import org.eclipse.core.filesystem.EFS;
 import org.eclipse.core.filesystem.IFileStore;
+import org.eclipse.core.resources.IFile;
+import org.eclipse.core.resources.ResourcesPlugin;
 import org.eclipse.jface.text.IDocument;
 import org.eclipse.ui.IEditorPart;
 import org.eclipse.ui.IWorkbenchPage;
 import org.eclipse.ui.ide.IDE;
 import org.eclipse.ui.texteditor.ITextEditor;
 
+import com.anthropic.claudecode.eclipse.editor.EditorParts;
 import com.anthropic.claudecode.eclipse.editor.UiHelper;
 import com.anthropic.claudecode.eclipse.mcp.McpTool;
 import com.anthropic.claudecode.eclipse.mcp.McpToolResult;
@@ -77,10 +81,20 @@ public McpToolResult execute(JsonObject params) {
                     return McpToolResult.error("No active workbench page");
                 }
 
-                IFileStore fileStore = EFS.getLocalFileSystem().getStore(Path.of(filePath).toUri());
-                IEditorPart editor = IDE.openEditorOnFileStore(page, fileStore);
+                IEditorPart editor;
+                if (EditorParts.isNonDiskPath(filePath)) {
+                    // A file another file system keeps (ABAP's semanticfs:): named by the URI
+                    // getOpenEditors reports, and opened through the workspace, not the disk.
+                    editor = openByUri(page, filePath);
+                    if (editor == null) return McpToolResult.error("No file found for: " + filePath);
+                } else {
+                    IFileStore fileStore = EFS.getLocalFileSystem().getStore(Path.of(filePath).toUri());
+                    editor = IDE.openEditorOnFileStore(page, fileStore);
+                }
 
-                if (editor instanceof ITextEditor textEditor && line > 0) {
+                // A multi-page editor's text is the page it is showing, not the editor itself.
+                ITextEditor textEditor = EditorParts.textEditorOf(editor);
+                if (textEditor != null && line > 0) {
                     IDocument doc = textEditor.getDocumentProvider().getDocument(textEditor.getEditorInput());
                     if (doc != null) {
                         int lineOffset = doc.getLineOffset(line - 1);
@@ -109,4 +123,18 @@ public McpToolResult execute(JsonObject params) {
             }
         });
     }
+
+    /**
+     * Opens the file a non-disk URI names: the workspace's own file when it has one (what the
+     * file's own editor, such as ADT's, expects to be given), else whatever the file system
+     * behind the URI has there. Null when there is no such file.
+     */
+    private static IEditorPart openByUri(IWorkbenchPage page, String path) throws Exception {
+        URI uri = EditorParts.nonDiskUriOf(path);
+        if (uri == null) return null;
+        IFile[] files = ResourcesPlugin.getWorkspace().getRoot().findFilesForLocationURI(uri);
+        if (files.length > 0) return IDE.openEditor(page, files[0]);
+        IFileStore store = EFS.getStore(uri);
+        return store.fetchInfo().exists() ? IDE.openEditorOnFileStore(page, store) : null;
+    }
 }

com.anthropic.claudecode.eclipse/test/com/anthropic/claudecode/eclipse/editor/EditorPartsTest.java

@@ -1,8 +1,10 @@
 package com.anthropic.claudecode.eclipse.editor;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.lang.reflect.Proxy;
 import java.net.URI;
@@ -172,4 +174,44 @@ void anyOtherInputGivesNoPath() {
         assertNull(EditorParts.pathOf(fake(IEditorInput.class, Map.of())));
         assertNull(EditorParts.pathOf((IEditorInput) null));
     }
+    // ---- non-disk paths ----
+
+    @Test
+    void aUriOfAnotherFileSystemIsNotADiskPath() {
+        assertTrue(EditorParts.isNonDiskPath("semanticfs:/E10_900_user_de/.adt/programs/zdemo.prog"));
+        assertTrue(EditorParts.isNonDiskPath("semanticfs:/E10/%2FDMO%2FCL_FLIGHT.aclass"));
+        assertTrue(EditorParts.isNonDiskPath("http://example.com/a"));
+    }
+
+    @Test
+    void everyKindOfDiskPathIsADiskPath() {
+        for (String path : new String[] { "/home/me/work/A.java", "/home/me/a:b/c.txt", "C:\\ws\\A.java", "D:/ws/a.txt",
+                "\\\\server\\share\\x.txt", "file:/C:/ws/notes.txt", "FILE:///tmp/x", "relative/A.java", "", "9:x" }) {
+            assertFalse(EditorParts.isNonDiskPath(path), path);
+        }
+        assertFalse(EditorParts.isNonDiskPath(null));
+    }
+
+    @Test
+    void aNonDiskPathGivesItsUriAndADiskPathGivesNone() {
+        String path = "semanticfs:/E10_900_user_de/zdemo.prog";
+        assertEquals(URI.create(path), EditorParts.nonDiskUriOf(path));
+        assertNull(EditorParts.nonDiskUriOf("/home/me/A.java"));
+        assertNull(EditorParts.nonDiskUriOf("C:\\ws\\A.java"));
+        assertNull(EditorParts.nonDiskUriOf(null));
+    }
+
+    @Test
+    void aNonDiskPathThatIsNotAValidUriGivesNoUriButIsStillNotADiskPath() {
+        String path = "semanticfs:/E10/a file with spaces.prog";
+        assertTrue(EditorParts.isNonDiskPath(path));
+        assertNull(EditorParts.nonDiskUriOf(path));
+    }
+
+    @Test
+    void theMessageForANonDiskPathNamesThePathAndTheFileSystem() {
+        String message = EditorParts.notOnDiskMessage("semanticfs:/E10/zdemo.prog");
+        assertTrue(message.startsWith("semanticfs:/E10/zdemo.prog is not a file on disk"), message);
+        assertTrue(message.contains("\"semanticfs\" file system"), message);
+    }
 }

com.anthropic.claudecode.eclipse/test/com/anthropic/claudecode/eclipse/tools/NonDiskDiffToolsTest.java

@@ -0,0 +1,40 @@
+package com.anthropic.claudecode.eclipse.tools;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+import com.anthropic.claudecode.eclipse.mcp.McpToolResult;
+import com.google.gson.JsonObject;
+
+/**
+ * The diff tools read and write files by disk path, so a file another file system keeps (ABAP's
+ * {@code semanticfs:}, #153) is refused with a plain message, before anything touches the
+ * workbench: this runs with none. It used to fail on the path, or be taken for a new file.
+ */
+class NonDiskDiffToolsTest {
+
+    private static final String ABAP = "semanticfs:/E10_900_user_de/.adt/programs/zdemo.prog";
+
+    private static void assertRefused(McpToolResult result) {
+        assertTrue(result.isError(), "refused");
+        String text = result.toJson().toString();
+        assertTrue(text.contains("is not a file on disk"), text);
+        assertTrue(text.contains(ABAP), text);
+    }
+
+    @Test
+    void openDiffRefusesAFileThatIsNotOnDisk() {
+        JsonObject params = new JsonObject();
+        params.addProperty("old_file_path", ABAP);
+        params.addProperty("new_file_contents", "REPORT zdemo.");
+        assertRefused(new OpenDiffTool().execute(params));
+    }
+
+    @Test
+    void acceptDiffRefusesAFileThatIsNotOnDisk() {
+        JsonObject params = new JsonObject();
+        params.addProperty("file_path", ABAP);
+        assertRefused(new AcceptDiffTool().execute(params));
+    }
+}