Fixed prompt area being collapsible to zero height by dragging the divider (#78)

CHANGELOG.md

@@ -1,3 +1,4 @@
+- Fixed prompt area being collapsible to zero height by dragging the divider
 - Fixed terminal scrolling to the beginning and locking when a choice/confirmation menu appears (https://github.com/nbclaudecodegui/NetbeansClaudeCodeGui/issues/22)
 
 # 0.21.50 (2026-04-19)

src/main/java/io/github/nbclaudecodegui/ui/ClaudePromptPanel.java

@@ -201,6 +201,18 @@ public ClaudePromptPanel(Consumer<String> onSend,
         });
     }
 
+    @Override
+    public java.awt.Dimension getMinimumSize() {
+        BorderLayout layout = (BorderLayout) getLayout();
+        java.awt.Component east = layout.getLayoutComponent(BorderLayout.EAST);
+        java.awt.Component west = layout.getLayoutComponent(BorderLayout.WEST);
+        int minH = 0;
+        if (east != null) minH = Math.max(minH, east.getMinimumSize().height);
+        if (west != null) minH = Math.max(minH, west.getMinimumSize().height);
+        java.awt.Insets ins = getInsets();
+        return new java.awt.Dimension(0, minH + ins.top + ins.bottom);
+    }
+
     // -------------------------------------------------------------------------
     // Public API
     // -------------------------------------------------------------------------

src/main/java/io/github/nbclaudecodegui/ui/ClaudeSessionTab.java

@@ -701,16 +701,17 @@ private void showChatLayout(JediTermWidget widget) {
         southCardLayout = new CardLayout();
         southCard = new JPanel(southCardLayout) {
             /**
-             * Returns (0, 0) so that JSplitPane can collapse the bottom panel
-             * freely when the tab is docked as a narrow side panel.
-             *
-             * Without this override, getMinimumSize() delegates to the visible
-             * child (e.g. promptPanel with a 3-row DecoratedTextArea + buttons),
-             * which reports a tall minimum height (~600 px). JSplitPane enforces
-             * that minimum, causing the divider to bounce back when the user tries
-             * to shrink the tab below that height (issue #19).
+             * Returns (0, 0) for non-prompt cards so that JSplitPane can collapse
+             * the bottom panel freely when the tab is docked as a narrow side panel
+             * (issue #19). For the prompt card, delegates to the visible child's
+             * minimum height so the divider cannot be dragged below the button column.
              */
             @Override public java.awt.Dimension getMinimumSize() {
+                if (CARD_PROMPT.equals(activeCard)) {
+                    for (java.awt.Component c : getComponents()) {
+                        if (c.isVisible()) return new java.awt.Dimension(0, c.getMinimumSize().height);
+                    }
+                }
                 return new java.awt.Dimension(0, 0);
             }
             @Override public java.awt.Dimension getPreferredSize() {

src/test/java/io/github/nbclaudecodegui/ui/ClaudeSessionTabMinSizeTest.java

@@ -1,5 +1,6 @@
 package io.github.nbclaudecodegui.ui;
 
+import java.awt.BorderLayout;
 import java.awt.Dimension;
 import javax.swing.JSplitPane;
 import javax.swing.JPanel;
@@ -8,49 +9,130 @@
 import static org.junit.jupiter.api.Assertions.*;
 
 /**
- * Regression test for issue #19: the session tab must be resizable below
- * ~600 px when docked as a side panel.
+ * Regression tests for prompt-area resize behaviour.
  *
- * <p>Root cause: {@code southCard.getMinimumSize()} was delegating to the
- * visible child component (e.g. promptPanel with a 3-row text area + buttons),
- * which reported a tall minimum height. {@link JSplitPane} enforces the
- * bottom component's minimum size, so the divider bounced back when the user
- * tried to shrink the tab below that height.
+ * <p>Issue #19: the session tab must be resizable below ~600 px when docked as
+ * a side panel — fixed by returning (0, 0) from {@code southCard.getMinimumSize()}.
  *
- * <p>Fix: {@code southCard.getMinimumSize()} now always returns (0, 0),
- * letting JSplitPane collapse the bottom panel freely.
+ * <p>Follow-up fix (scroll-lock): the prompt area must not be collapsible to
+ * zero height — fixed by having {@code ClaudePromptPanel.getMinimumSize()}
+ * return the height of its button columns, and by having {@code southCard}
+ * delegate to the visible child's minimum when {@code CARD_PROMPT} is active.
  */
 class ClaudeSessionTabMinSizeTest {
 
     /**
-     * Verifies that {@code southCard}'s minimum size is (0, 0) so that
-     * JSplitPane does not enforce a large lower bound on the tab height.
+     * Verifies that {@code southCard}'s minimum size is (0, 0) when a non-prompt
+     * card is active (e.g. CARD_CHOICE), so JSplitPane does not enforce a large
+     * lower bound on the tab height (issue #19).
      */
     @Test
-    void southCardMinimumSizeIsZero() throws Exception {
+    void southCardMinimumSizeIsZeroForChoiceCard() throws Exception {
         SwingUtilities.invokeAndWait(() -> {
-            // Simulate the southCard construction from showChatLayout():
-            // an anonymous JPanel subclass with getMinimumSize() returning (0,0).
+            String[] activeCard = {"choice"};
             java.awt.CardLayout cardLayout = new java.awt.CardLayout();
             JPanel southCard = new JPanel(cardLayout) {
                 @Override public Dimension getMinimumSize() {
+                    if ("prompt".equals(activeCard[0])) {
+                        for (java.awt.Component c : getComponents()) {
+                            if (c.isVisible()) return new Dimension(0, c.getMinimumSize().height);
+                        }
+                    }
                     return new Dimension(0, 0);
                 }
             };
 
-            // Add a child with a large preferred/minimum size (mirrors promptPanel).
-            JPanel tallChild = new JPanel() {
+            JPanel choiceChild = new JPanel() {
                 @Override public Dimension getMinimumSize()   { return new Dimension(400, 600); }
                 @Override public Dimension getPreferredSize() { return new Dimension(400, 600); }
             };
-            southCard.add(tallChild, "prompt");
+            southCard.add(choiceChild, "choice");
+            cardLayout.show(southCard, "choice");
+
+            Dimension min = southCard.getMinimumSize();
+            assertEquals(0, min.width,  "southCard min width must be 0 for choice card (issue #19)");
+            assertEquals(0, min.height, "southCard min height must be 0 for choice card (issue #19)");
+        });
+    }
+
+    /**
+     * Verifies that {@code southCard}'s minimum height is driven by the visible
+     * child when {@code CARD_PROMPT} is active — so the divider cannot be
+     * dragged below the button column height.
+     */
+    @Test
+    void southCardMinimumHeightIsFromChildWhenPromptCardActive() throws Exception {
+        SwingUtilities.invokeAndWait(() -> {
+            String[] activeCard = {"prompt"};
+            java.awt.CardLayout cardLayout = new java.awt.CardLayout();
+            JPanel southCard = new JPanel(cardLayout) {
+                @Override public Dimension getMinimumSize() {
+                    if ("prompt".equals(activeCard[0])) {
+                        for (java.awt.Component c : getComponents()) {
+                            if (c.isVisible()) return new Dimension(0, c.getMinimumSize().height);
+                        }
+                    }
+                    return new Dimension(0, 0);
+                }
+            };
+
+            JPanel promptChild = new JPanel() {
+                @Override public Dimension getMinimumSize()   { return new Dimension(400, 42); }
+                @Override public Dimension getPreferredSize() { return new Dimension(400, 100); }
+            };
+            southCard.add(promptChild, "prompt");
             cardLayout.show(southCard, "prompt");
 
             Dimension min = southCard.getMinimumSize();
-            assertEquals(0, min.width,
-                    "southCard minimum width must be 0 so JSplitPane can resize freely (issue #19)");
-            assertEquals(0, min.height,
-                    "southCard minimum height must be 0 so JSplitPane can resize freely (issue #19)");
+            assertEquals(0,  min.width,  "southCard min width must be 0 even for prompt card");
+            assertEquals(42, min.height, "southCard min height must match button column height when prompt card active");
+        });
+    }
+
+    /**
+     * Verifies that {@code ClaudePromptPanel.getMinimumSize()} returns a height
+     * driven by the EAST/WEST button columns, not the CENTER scroll pane.
+     */
+    @Test
+    void promptPanel_minimumHeight_isDrivenByButtonColumns() throws Exception {
+        SwingUtilities.invokeAndWait(() -> {
+            JPanel promptPanel = new JPanel(new BorderLayout()) {
+                @Override
+                public Dimension getMinimumSize() {
+                    BorderLayout layout = (BorderLayout) getLayout();
+                    java.awt.Component east = layout.getLayoutComponent(BorderLayout.EAST);
+                    java.awt.Component west = layout.getLayoutComponent(BorderLayout.WEST);
+                    int minH = 0;
+                    if (east != null) minH = Math.max(minH, east.getMinimumSize().height);
+                    if (west != null) minH = Math.max(minH, west.getMinimumSize().height);
+                    java.awt.Insets ins = getInsets();
+                    return new Dimension(0, minH + ins.top + ins.bottom);
+                }
+            };
+
+            // CENTER: large textarea (should NOT drive minimum)
+            JPanel center = new JPanel() {
+                @Override public Dimension getMinimumSize() { return new Dimension(400, 600); }
+            };
+            // EAST: button column
+            JPanel east = new JPanel() {
+                @Override public Dimension getMinimumSize() { return new Dimension(30, 55); }
+            };
+            // WEST: button column
+            JPanel west = new JPanel() {
+                @Override public Dimension getMinimumSize() { return new Dimension(30, 40); }
+            };
+
+            promptPanel.add(center, BorderLayout.CENTER);
+            promptPanel.add(east,   BorderLayout.EAST);
+            promptPanel.add(west,   BorderLayout.WEST);
+
+            Dimension min = promptPanel.getMinimumSize();
+            assertEquals(0, min.width, "promptPanel minimum width must be 0");
+            assertTrue(min.height >= 55,
+                    "promptPanel minimum height must be >= east button column height (55), got " + min.height);
+            assertTrue(min.height < 600,
+                    "promptPanel minimum height must not be driven by CENTER textarea (600), got " + min.height);
         });
     }