fix(jetbrains): reconcile session layout cache

packages/kilo-jetbrains/frontend/src/main/kotlin/ai/kilocode/client/session/ui/SessionLayout.kt

@@ -152,6 +152,33 @@ open class SessionLayoutPanel(
         layout = SessionLayout(gap, pad)
     }
 
+    override fun doLayout() {
+        super.doLayout()
+        reconcileValidateRoot()
+    }
+
+    /**
+     * Keep the parent [SessionLayout]'s cached height honest across validate-root boundaries.
+     *
+     * A validate root, such as a settled [ai.kilocode.client.session.views.TurnView], can be laid out
+     * independently by `RepaintManager`. Its `isValid` flag can flip back to `true` before the parent
+     * transcript remeasures it, so [SessionLayout] may otherwise keep stacking it at a stale cached
+     * height until some unrelated resize changes the cache key.
+     *
+     * Once this root has laid out its own content, its rendered height should match its preferred
+     * height. If it does not, the parent cache is stale: drop this entry and revalidate the parent so
+     * the outer transcript geometry follows the content. Non-roots are skipped because their
+     * invalidation already propagates to the parent and keeps `isValid` an honest cache signal.
+     */
+    private fun reconcileValidateRoot() {
+        if (!isValidateRoot()) return
+        val host = parent ?: return
+        val layout = host.layout as? SessionLayout ?: return
+        if (preferredSize.height == height) return
+        layout.forget(this)
+        (host as? javax.swing.JComponent)?.revalidate()
+    }
+
     override fun getScrollableTracksViewportWidth() = true
     override fun getScrollableTracksViewportHeight() = false
     override fun getPreferredScrollableViewportSize(): Dimension = preferredSize

packages/kilo-jetbrains/frontend/src/test/kotlin/ai/kilocode/client/session/ui/SessionLayoutTest.kt

@@ -361,6 +361,34 @@ class SessionLayoutTest : BasePlatformTestCase() {
         assertEquals(sCount + 1, second.count)
     }
 
+    fun `test validate root child reconciles stale parent cache after self layout`() {
+        val p = panel(width = 300)
+        val child = rootProbe(root = true)
+        p.add(child)
+        p.doLayout()
+        child.markValid()
+        child.preferred = 80
+
+        child.doLayout()
+        p.doLayout()
+
+        assertEquals(80, child.height)
+    }
+
+    fun `test non validate root child keeps parent cache until it invalidates upward`() {
+        val p = panel(width = 300)
+        val child = rootProbe(root = false)
+        p.add(child)
+        p.doLayout()
+        child.markValid()
+        child.preferred = 80
+
+        child.doLayout()
+        p.doLayout()
+
+        assertEquals(20, child.height)
+    }
+
     // ---- helpers ------
 
     /** A fixed-height JLabel. The width is reported as 0 until layout sets it. */
@@ -394,4 +422,24 @@ class SessionLayoutTest : BasePlatformTestCase() {
             return Dimension(0, height)
         }
     }
+
+    private fun rootProbe(root: Boolean) = object : SessionLayoutPanel() {
+        var preferred = 20
+        private var valid = false
+
+        override fun isValid() = valid
+
+        override fun invalidate() {
+            valid = false
+            super.invalidate()
+        }
+
+        fun markValid() {
+            valid = true
+        }
+
+        override fun isValidateRoot() = root
+
+        override fun getPreferredSize(): Dimension = Dimension(0, preferred)
+    }
 }