Fixed model discovery failing when CR is absorbed as newline in prompt

CHANGELOG.md

@@ -1,3 +1,5 @@
+- Fixed model discovery failing when Enter was absorbed as a newline in the prompt instead of submitting the /model command (race condition under load)
+
 # 0.22.24 (2026-04-29)
 
 - Fixed model name detection for new Claude CLI format where the default item has a long label ("Default (recommended)") with only 2-space alignment, and for model names that include a space (e.g. "Sonnet 4")

pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>io.github.nbclaudecodegui</groupId>
     <artifactId>netbeans-claude-code-gui</artifactId>
-    <version>0.22.33-SNAPSHOT</version>
+    <version>0.22.34-SNAPSHOT</version>
     <packaging>nbm</packaging>
     <name>Netbeans Claude Code GUI</name>
     <description>NetBeans plugin that provides a GUI for Claude Code CLI — run claude code sessions directly inside the IDE.</description>

src/main/java/io/github/nbclaudecodegui/controller/ClaudeSessionController.java

@@ -59,6 +59,9 @@ public class ClaudeSessionController {
     /** ESC byte sent to the PTY (dismiss autocomplete, close menus). */
     private static final byte[] PTY_ESC = {0x1b};
 
+    /** DEL character (0x7F) — acts as BackSpace in xterm-256color terminals. */
+    private static final byte[] PTY_BACKSPACE = {0x7f};
+
     private static final int MAX_MODEL_DISCOVERY_ATTEMPTS = 1;
 
     private final ClaudeSessionModel model;
@@ -803,6 +806,14 @@ void discoverModels() {
                         LOG.fine("[discoverModels] ModelMenuParser found models on poll " + (poll + 1));
                         break;
                     }
+                    // If ❯ /model is still in the prompt with a blank line below it, CR was
+                    // absorbed as a newline — retry: BackSpace to remove the blank line, then CR.
+                    if (poll < 12 && isModelCommandPendingWithBlankLine(lines)) {
+                        LOG.fine("[discoverModels] /model pending with blank line on poll " + (poll + 1) + ", retrying CR");
+                        connector.write(PTY_BACKSPACE);
+                        Thread.sleep(200);
+                        connector.write("\r");
+                    }
                 }
 
                 // Scan the rolling PTY line buffer for the /model hint line, which is
@@ -1261,6 +1272,30 @@ private void startStatusPollTimer() {
         statusTimer.start();
     }
 
+    /**
+     * Returns {@code true} when the screen shows {@code ❯ /model} followed by a blank line
+     * and then a separator — meaning CR was absorbed as a newline instead of submitting the
+     * command. Only the active input area (cursor line) is checked to avoid false positives
+     * when "/model" appears in Claude's output history.
+     */
+    boolean isModelCommandPendingWithBlankLine(List<String> lines) {
+        for (int i = 0; i < lines.size() - 2; i++) {
+            String trimmed = lines.get(i).trim();
+            if ((trimmed.startsWith("❯") || trimmed.startsWith(">")) && trimmed.contains("/model")) {
+                if (lines.get(i + 1).isBlank() && isSeparatorLine(lines.get(i + 2))) {
+                    return true;
+                }
+            }
+        }
+        return false;
+    }
+
+    private static boolean isSeparatorLine(String line) {
+        String t = line.trim();
+        return t.length() >= 4 && t.chars().allMatch(c ->
+                c == '─' || c == '━' || c == '—' || c == '-' || c == '=');
+    }
+
     /**
      * Opens the {@code /model} selection menu via a safe three-step sequence:
      * type {@code /model}, wait, ESC to dismiss autocomplete (keeping the

src/test/java/io/github/nbclaudecodegui/controller/ClaudeSessionControllerTest.java

@@ -661,6 +661,47 @@ void discoverModels() {
                 "Blocking dialog must be shown to the user while discovery is deferred");
     }
 
+    // -------------------------------------------------------------------------
+    // isModelCommandPendingWithBlankLine
+    // -------------------------------------------------------------------------
+
+    @Test
+    void isModelCommandPendingWithBlankLine_detectsNewlineInsertedByEnter() {
+        List<String> lines = List.of(
+                "   ● Built successfully. Install target/nbm/foo.nbm and test.",
+                "",
+                "  ─────────────────────────────────────────────────────────────",
+                "  ──────── fix-kotlin-extensions-nosuchmethoderror ──",
+                "  ❯ /model",
+                "",
+                "  ─────────────────────────────────────────────────────────────",
+                "  ─────────────────────────────────────────────────────────────",
+                "  ─────────────────────────────────",
+                "    ⏵⏵ bypass permissions on (shift+tab to cycle)"
+        );
+        assertTrue(controller.isModelCommandPendingWithBlankLine(lines));
+    }
+
+    @Test
+    void isModelCommandPendingWithBlankLine_falseWhenNoBlankAfterModel() {
+        List<String> lines = List.of(
+                "  ❯ /model",
+                "  ─────────────────────────────────────────────────────────────"
+        );
+        assertFalse(controller.isModelCommandPendingWithBlankLine(lines));
+    }
+
+    @Test
+    void isModelCommandPendingWithBlankLine_falseWhenModelInHistory() {
+        List<String> lines = List.of(
+                "  You used /model earlier",
+                "",
+                "  ─────────────────────────────────────────────────────────────",
+                "  ❯ "
+        );
+        assertFalse(controller.isModelCommandPendingWithBlankLine(lines));
+    }
+
     // -------------------------------------------------------------------------
     // No-op listener base class
     // -------------------------------------------------------------------------