Fixed diff panel height and stale card on second diff (#71)

CHANGELOG.md

@@ -1,3 +1,5 @@
+- Fixed diff panel appearing at wrong height (nearly invisible) after Reset Windows or on first use
+- Fixed second diff in the same Claude session being invisible (stale card accumulation)
 - Fixed terminal scrolling to the beginning when a choice menu or diff panel appears (regression since 0.20.20)
 
 # 0.21.46 (2026-04-17)

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

@@ -162,9 +162,10 @@ public class ClaudeSessionTab extends TopComponent
     private JediTermWidget  terminalWidget;
     private JSplitPane      splitPane;
     private JPanel          errorPanel;
-    private JPanel          southCard;
-    private CardLayout      southCardLayout;
-    private String          activeCard;
+    JPanel          southCard;
+    CardLayout      southCardLayout;
+    String          activeCard;
+    JPanel          currentDiffCard;
     private Runnable        pendingDiffOnClose;
 
     // -------------------------------------------------------------------------
@@ -741,19 +742,10 @@ private void showChatLayout(JediTermWidget widget) {
             public void componentResized(ComponentEvent e) {
                 int total = splitPane.getHeight();
                 if (total <= 0) return;
-                int bottom;
-                if (!savingEnabled[0]) {
-                    bottom = savedBottomHeight > 0 ? savedBottomHeight
-                                                   : southCard.getPreferredSize().height;
-                    savingEnabled[0] = true;
-                } else {
-                    bottom = NbPreferences.forModule(ClaudeSessionTab.class)
-                            .getInt(getSavedCardKey(), southCard.getPreferredSize().height);
-                }
-                int divLoc = total - splitPane.getDividerSize() - bottom;
-                LOG.fine(sessionTag + "[splitPane resize] total=" + total
-                        + " bottom=" + bottom + " divLoc=" + divLoc);
-                splitPane.setDividerLocation(divLoc);
+                LOG.fine(sessionTag + "[componentResized] activeCard=" + activeCard
+                        + " total=" + total + " savedBottomHeight=" + savedBottomHeight);
+                applyDividerForCard(activeCard, total, savedBottomHeight);
+                savingEnabled[0] = true;
             }
         });
         splitPane.addPropertyChangeListener(JSplitPane.DIVIDER_LOCATION_PROPERTY, e -> {
@@ -893,11 +885,53 @@ private void showStartError(String command, String error,
      * @return preference key string
      */
     private String getSavedCardKey() {
-        if (CARD_PROMPT.equals(activeCard) || activeCard == null) return "bottomHeight";
-        return activeCard + "Height";
+        return getSavedCardKeyFor(activeCard);
+    }
+
+    /**
+     * Reads the saved divider height for {@code card}, falls back to sensible defaults,
+     * sets the divider location, and returns the bottom height used.
+     * {@code legacyPromptHeight} is the pre-migration "bottomHeight" value (pass -1 to skip).
+     */
+    private int applyDividerForCard(String card, int total, int legacyPromptHeight) {
+        int saved = NbPreferences.forModule(ClaudeSessionTab.class)
+                .getInt(getSavedCardKeyFor(card), -1);
+        int bottom = computeBottomHeight(card, total, saved, legacyPromptHeight,
+                southCard.getPreferredSize().height);
+        int divLoc = total - splitPane.getDividerSize() - bottom;
+        LOG.fine(sessionTag + "[applyDivider] card=" + card
+                + " total=" + total + " saved=" + saved
+                + " legacy=" + legacyPromptHeight
+                + " preferred=" + southCard.getPreferredSize().height
+                + " bottom=" + bottom + " divLoc=" + divLoc);
+        if (divLoc >= 0) splitPane.setDividerLocation(divLoc);
+        return bottom;
+    }
+
+    /**
+     * Pure function: computes the south-panel height for a given card.
+     * Extracted for unit testing — no Swing state access.
+     *
+     * @param card              active card name (CARD_PROMPT or CARD_DIFF)
+     * @param total             total splitPane height
+     * @param saved             persisted height (negative means not saved)
+     * @param legacyPromptHeight "bottomHeight" pref value for backward-compat (negative to skip)
+     * @param preferredHeight   southCard preferred height (fallback)
+     */
+    static int computeBottomHeight(String card, int total, int saved,
+                                   int legacyPromptHeight, int preferredHeight) {
+        if (saved > 0) return saved;
+        if (CARD_DIFF.equals(card)) return total * 2 / 3;
+        if (CARD_PROMPT.equals(card) && legacyPromptHeight > 0) return legacyPromptHeight;
+        return preferredHeight;
     }
 
-    private void switchSouthCard(String card) {
+    String getSavedCardKeyFor(String card) {
+        if (CARD_PROMPT.equals(card) || card == null) return "bottomHeight";
+        return card + "Height";
+    }
+
+    void switchSouthCard(String card) {
         if (southCard == null || southCardLayout == null) return;
         activeCard = card;
         southCardLayout.show(southCard, card);
@@ -912,11 +946,14 @@ private void switchSouthCard(String card) {
         if (!CARD_CHOICE.equals(card)) {
             // restore divider for this card
             int total = splitPane.getHeight();
+            LOG.fine(sessionTag + "[switchSouthCard] card=" + card + " total=" + total);
             if (total > 0) {
-                int bottom = NbPreferences.forModule(ClaudeSessionTab.class)
-                        .getInt(getSavedCardKey(), DEFAULT_DIFF_HEIGHT);
-                int divLoc = total - splitPane.getDividerSize() - bottom;
-                splitPane.setDividerLocation(divLoc);
+                applyDividerForCard(card, total, -1);
+            } else {
+                SwingUtilities.invokeLater(() -> {
+                    int t = splitPane != null ? splitPane.getHeight() : 0;
+                    if (t > 0) applyDividerForCard(activeCard, t, -1);
+                });
             }
         } else {
             // lock divider for choice menu
@@ -1058,6 +1095,7 @@ private void cleanupChatLayout() {
             southCard       = null;
             southCardLayout = null;
             activeCard      = null;
+            currentDiffCard = null;
         }
         if (errorPanel != null) {
             remove(errorPanel);
@@ -1124,14 +1162,19 @@ public boolean showEmbeddedDiff(boolean outsideProject, String outsideWarning,
             permPanel.showWarning(outsideWarning);
         }
 
+        if (currentDiffCard != null) {
+            southCard.remove(currentDiffCard);
+            currentDiffCard = null;
+        }
         JPanel diffCard = new JPanel(new BorderLayout());
         if (toolbar != null) {
             diffCard.add(toolbar, BorderLayout.NORTH);
         }
         diffCard.add(diffComponent, BorderLayout.CENTER);
         diffCard.add(permPanel,     BorderLayout.SOUTH);
 
-        southCard.add(diffCard, CARD_DIFF);
+        currentDiffCard = diffCard;
+        southCard.add(currentDiffCard, CARD_DIFF);
 
         pendingDiffOnClose = onTabClose;
         switchSouthCard(CARD_DIFF);
@@ -1148,6 +1191,10 @@ public void hideEmbeddedDiff() {
         pendingDiffOnClose = null;
         if (southCard == null) return;
         switchSouthCard(CARD_PROMPT);
+        if (currentDiffCard != null) {
+            southCard.remove(currentDiffCard);
+            currentDiffCard = null;
+        }
         revalidate();
         repaint();
     }

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

@@ -0,0 +1,175 @@
+package io.github.nbclaudecodegui.ui;
+
+import java.awt.CardLayout;
+import java.awt.Component;
+import javax.swing.JLabel;
+import javax.swing.JPanel;
+import javax.swing.JSplitPane;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+/**
+ * Tests for the two embedded-diff bugs fixed in 0.22.2:
+ * <ol>
+ *   <li>Stale {@code CARD_DIFF} accumulates in the CardLayout when
+ *       {@link ClaudeSessionTab#showEmbeddedDiff} is called multiple times.</li>
+ *   <li>Wrong divider position when the diff card first appears ({@link
+ *       ClaudeSessionTab#computeBottomHeight} default logic).</li>
+ * </ol>
+ */
+class ClaudeSessionTabDiffTest {
+
+    // -------------------------------------------------------------------------
+    // Bug 1 — computeBottomHeight default values
+    // -------------------------------------------------------------------------
+
+    @Test
+    void computeBottomHeight_savedValue_returnsSaved() {
+        assertEquals(123, ClaudeSessionTab.computeBottomHeight("diff", 900, 123, -1, 50));
+    }
+
+    @Test
+    void computeBottomHeight_diffCard_noSaved_returnsTwoThirdsTotal() {
+        int total = 900;
+        int expected = total * 2 / 3;  // 600
+        assertEquals(expected, ClaudeSessionTab.computeBottomHeight("diff", total, -1, -1, 50));
+    }
+
+    @Test
+    void computeBottomHeight_promptCard_noSaved_legacyPresent_returnsLegacy() {
+        assertEquals(200, ClaudeSessionTab.computeBottomHeight("prompt", 900, -1, 200, 50));
+    }
+
+    @Test
+    void computeBottomHeight_promptCard_noSaved_noLegacy_returnsPreferred() {
+        assertEquals(50, ClaudeSessionTab.computeBottomHeight("prompt", 900, -1, -1, 50));
+    }
+
+    @Test
+    void computeBottomHeight_diffCard_savedZeroIgnored_returnsTwoThirds() {
+        // saved == 0 is treated as "not saved" (condition is saved > 0)
+        int total = 600;
+        assertEquals(total * 2 / 3, ClaudeSessionTab.computeBottomHeight("diff", total, 0, -1, 50));
+    }
+
+    // -------------------------------------------------------------------------
+    // getSavedCardKeyFor
+    // -------------------------------------------------------------------------
+
+    @Test
+    void savedCardKey_promptCard_returnsBackwardCompatKey() {
+        ClaudeSessionTab tab = new ClaudeSessionTab();
+        assertEquals("bottomHeight", tab.getSavedCardKeyFor("prompt"));
+    }
+
+    @Test
+    void savedCardKey_nullCard_returnsBackwardCompatKey() {
+        ClaudeSessionTab tab = new ClaudeSessionTab();
+        assertEquals("bottomHeight", tab.getSavedCardKeyFor(null));
+    }
+
+    @Test
+    void savedCardKey_diffCard_returnsDiffHeight() {
+        ClaudeSessionTab tab = new ClaudeSessionTab();
+        assertEquals("diffHeight", tab.getSavedCardKeyFor("diff"));
+    }
+
+    // -------------------------------------------------------------------------
+    // Bug 2 — stale CARD_DIFF accumulates in CardLayout
+    // -------------------------------------------------------------------------
+
+    /**
+     * Sets up a minimal south-card environment on a tab (without starting a PTY)
+     * so that {@link ClaudeSessionTab#showEmbeddedDiff} can be called.
+     * {@code switchSouthCard} is overridden to a no-op to avoid needing a full
+     * JediTerm widget and splitPane.
+     */
+    private ClaudeSessionTab tabWithSouthCard() {
+        ClaudeSessionTab tab = new ClaudeSessionTab() {
+            @Override
+            void switchSouthCard(String card) {
+                // no-op: avoids splitPane / terminalWidget dependency in tests
+                activeCard = card;
+            }
+        };
+        CardLayout layout = new CardLayout();
+        JPanel south = new JPanel(layout);
+        tab.southCard = south;
+        tab.southCardLayout = layout;
+        tab.activeCard = "prompt";
+        return tab;
+    }
+
+    @Test
+    void showEmbeddedDiff_firstCall_addsDiffCard() {
+        ClaudeSessionTab tab = tabWithSouthCard();
+
+        boolean shown = tab.showEmbeddedDiff(false, null, null,
+                new JLabel("diff1"),
+                new FileDiffPermissionPanel(() -> {}, r -> {}, () -> {}, () -> {}, null),
+                null);
+
+        assertTrue(shown, "showEmbeddedDiff must return true when southCard is set");
+        assertNotNull(tab.currentDiffCard, "currentDiffCard must be set after first call");
+        // southCard now contains exactly one CARD_DIFF panel
+        assertEquals(1, countComponents(tab.southCard));
+    }
+
+    @Test
+    void showEmbeddedDiff_secondCall_replacesOldCard() {
+        ClaudeSessionTab tab = tabWithSouthCard();
+
+        tab.showEmbeddedDiff(false, null, null,
+                new JLabel("diff1"),
+                new FileDiffPermissionPanel(() -> {}, r -> {}, () -> {}, () -> {}, null),
+                null);
+        JPanel firstCard = tab.currentDiffCard;
+
+        tab.showEmbeddedDiff(false, null, null,
+                new JLabel("diff2"),
+                new FileDiffPermissionPanel(() -> {}, r -> {}, () -> {}, () -> {}, null),
+                null);
+        JPanel secondCard = tab.currentDiffCard;
+
+        assertNotSame(firstCard, secondCard, "currentDiffCard must be replaced on second call");
+        // Only the new card should remain in southCard — no stale accumulation
+        assertEquals(1, countComponents(tab.southCard),
+                "southCard must contain exactly one diff card after second showEmbeddedDiff");
+        assertFalse(isChildOf(tab.southCard, firstCard),
+                "Old diff card must be removed from southCard");
+        assertTrue(isChildOf(tab.southCard, secondCard),
+                "New diff card must be present in southCard");
+    }
+
+    @Test
+    void hideEmbeddedDiff_removesCardAndClearsField() {
+        ClaudeSessionTab tab = tabWithSouthCard();
+
+        tab.showEmbeddedDiff(false, null, null,
+                new JLabel("diff"),
+                new FileDiffPermissionPanel(() -> {}, r -> {}, () -> {}, () -> {}, null),
+                null);
+
+        tab.hideEmbeddedDiff();
+
+        assertNull(tab.currentDiffCard, "currentDiffCard must be null after hide");
+        assertEquals(0, countComponents(tab.southCard),
+                "southCard must have no diff card after hide");
+    }
+
+    // -------------------------------------------------------------------------
+    // Helpers
+    // -------------------------------------------------------------------------
+
+    private static int countComponents(JPanel panel) {
+        return panel.getComponentCount();
+    }
+
+    private static boolean isChildOf(JPanel parent, Component child) {
+        for (int i = 0; i < parent.getComponentCount(); i++) {
+            if (parent.getComponent(i) == child) return true;
+        }
+        return false;
+    }
+}