fix(cli): close handle on all error paths, return Optional from openOnWorker

ViewCommand leaked the opened VortexHandle if anything threw between opening it
and entering the grid-source try block (Sonar S2095, BLOCKER → reliability E):
the close lived only in the inner try's finally. Wrap every post-open step in a
try/finally that closes the handle on the worker thread.

CliHandles.openOnWorker now returns Optional<VortexHandle> instead of null, and
ViewCommand/TuiCommand branch on isEmpty(). The null sentinel made Sonar flag
the missing-file guards as always-false (S2583) because it lost dataflow across
the runAndAwait lambda; Optional both removes the smell and is idiomatic.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: dfa1

cli/src/main/java/io/github/dfa1/vortex/cli/CliHandles.java

@@ -10,6 +10,7 @@
 import java.net.URISyntaxException;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.util.Optional;
 import java.util.concurrent.atomic.AtomicReference;
 
 /// Shared handle plumbing for the interactive subcommands (`view`, `tui`).
@@ -27,10 +28,10 @@ private CliHandles() {
     ///
     /// @param worker the I/O worker that owns the handle's arena
     /// @param target a local path or an `http(s)://` URL
-    /// @return the opened handle, or `null` if the target is missing or malformed
+    /// @return the opened handle, or empty if the target is missing or malformed
     /// @throws InterruptedException if interrupted while waiting on the worker
     /// @throws IOException          if opening the file or URL fails
-    static VortexHandle openOnWorker(IoWorker worker, String target)
+    static Optional<VortexHandle> openOnWorker(IoWorker worker, String target)
             throws InterruptedException, IOException {
         AtomicReference<VortexHandle> handle = new AtomicReference<>();
         AtomicReference<IOException> failure = new AtomicReference<>();
@@ -44,7 +45,7 @@ static VortexHandle openOnWorker(IoWorker worker, String target)
         if (failure.get() != null) {
             throw failure.get();
         }
-        return handle.get();
+        return Optional.ofNullable(handle.get());
     }
 
     /// Closes `handle` on the worker thread that opened it.

cli/src/main/java/io/github/dfa1/vortex/cli/TuiCommand.java

@@ -7,6 +7,7 @@
 
 import java.io.IOException;
 import java.io.PrintStream;
+import java.util.Optional;
 
 final class TuiCommand {
 
@@ -19,10 +20,11 @@ static int run(String[] args) {
             return ExitStatus.USAGE_ERROR;
         }
         try (IoWorker worker = new IoWorker("vortex-tui-io")) {
-            VortexHandle handle = CliHandles.openOnWorker(worker, args[1]);
-            if (handle == null) {
+            Optional<VortexHandle> opened = CliHandles.openOnWorker(worker, args[1]);
+            if (opened.isEmpty()) {
                 return ExitStatus.FILE_NOT_FOUND;
             }
+            VortexHandle handle = opened.get();
             try {
                 VortexInspectorTui.show(handle, worker, progressBar(System.err));
             } finally {

cli/src/main/java/io/github/dfa1/vortex/cli/ViewCommand.java

@@ -6,6 +6,7 @@
 import io.github.dfa1.vortex.reader.VortexHandle;
 
 import java.io.IOException;
+import java.util.Optional;
 
 @SuppressWarnings("java:S106")
 final class ViewCommand {
@@ -22,24 +23,27 @@ static int run(String[] args) {
             System.err.print("Opening file... ");
             System.err.flush();
             long tOpen = System.nanoTime();
-            VortexHandle handle = CliHandles.openOnWorker(worker, args[1]);
-            if (handle == null) {
+            Optional<VortexHandle> opened = CliHandles.openOnWorker(worker, args[1]);
+            if (opened.isEmpty()) {
                 return ExitStatus.FILE_NOT_FOUND;
             }
-            System.err.println("done (" + (System.nanoTime() - tOpen) / 1_000_000L + " ms)");
+            VortexHandle handle = opened.get();
+            try {
+                System.err.println("done (" + (System.nanoTime() - tOpen) / 1_000_000L + " ms)");
 
-            System.err.print("Indexing chunks... ");
-            System.err.flush();
-            long tIdx = System.nanoTime();
-            try (LazyGridSource source = LazyGridSource.open(handle, worker)) {
-                long ms = (System.nanoTime() - tIdx) / 1_000_000L;
-                System.err.println("done — " + source.totalRows() + " rows × "
-                        + source.columns().size() + " cols (" + ms + " ms)");
-                VortexGridTui.show(args[1], source);
+                System.err.print("Indexing chunks... ");
+                System.err.flush();
+                long tIdx = System.nanoTime();
+                try (LazyGridSource source = LazyGridSource.open(handle, worker)) {
+                    long ms = (System.nanoTime() - tIdx) / 1_000_000L;
+                    System.err.println("done — " + source.totalRows() + " rows × "
+                            + source.columns().size() + " cols (" + ms + " ms)");
+                    VortexGridTui.show(args[1], source);
+                }
+                return ExitStatus.OK;
             } finally {
                 CliHandles.closeOnWorker(worker, handle);
             }
-            return ExitStatus.OK;
         } catch (IOException | RuntimeException | InterruptedException e) {
             if (e instanceof InterruptedException) {
                 Thread.currentThread().interrupt();