From d0d1577bfe54bc29632d7be07cfc617220a3caa4 Mon Sep 17 00:00:00 2001
From: Vitor Pamplona <vitor@vitorpamplona.com>
Date: Mon, 22 Jun 2026 19:00:24 -0400
Subject: [PATCH] fix(napplets): remove the stray white band at the bottom of
 the applet WebView

Two edge-to-edge issues on the napplet/nsite host, both surfacing as a white strip below
the applet on a light page:

- Double bottom inset. The root inset listener turned the system-bar/cutout insets into
  padding but returned them un-consumed, so the child WebView (which on targetSdk 35+
  auto-applies any insets it receives to its web content) padded the bottom a SECOND time.
  Zero those types before they reach the WebView, keeping IME flowing so keyboard resize
  still works.

- Over-scroll reveal. Forcing a scroll past the content edge stretched the view and
  exposed the shell document's background behind the applet iframe. WebView.overScrollMode
  only governs the outer frame, so also inject `overscroll-behavior: none` into the applet
  document (alongside the shim) to kill the stretch at the source, theme-independently.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 .../amethyst/napplethost/NappletContentServer.kt  |  8 +++++++-
 .../amethyst/napplethost/NappletHostActivity.kt   | 15 +++++++++++++--
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/nappletHost/src/main/kotlin/com/vitorpamplona/amethyst/napplethost/NappletContentServer.kt b/nappletHost/src/main/kotlin/com/vitorpamplona/amethyst/napplethost/NappletContentServer.kt
index 360475cd17..0b569af9c4 100644
--- a/nappletHost/src/main/kotlin/com/vitorpamplona/amethyst/napplethost/NappletContentServer.kt
+++ b/nappletHost/src/main/kotlin/com/vitorpamplona/amethyst/napplethost/NappletContentServer.kt
@@ -169,9 +169,15 @@ class NappletContentServer(
     /** Inserts the `window.napplet` client shim into the applet's HTML document. */
     private fun injectShim(html: ByteArray): ByteArray {
         val text = html.decodeToString()
+        // Disable the document's overscroll affordance (the bounce/stretch): the Android-level
+        // WebView.overScrollMode only governs the outer frame, so an applet whose own root background is
+        // transparent stretched on over-scroll and exposed the shell's background behind it (a stray
+        // white band at the bottom). `overscroll-behavior: none` removes the stretch at the source,
+        // theme-independently. Allowed by the app CSP's `style-src 'unsafe-inline'`.
+        val style = "<style>html,body{overscroll-behavior:none !important}</style>"
         // In website mode, set the NIP-07 flag synchronously *before* the shim so window.nostr installs.
         val nip07Flag = if (websiteMode) "<script>window.__nappletNip07=true;</script>" else ""
-        val script = "$nip07Flag<script>$shimJs</script>"
+        val script = "$style$nip07Flag<script>$shimJs</script>"
         val headIdx = text.indexOf("<head", ignoreCase = true)
         val injected =
             when {
diff --git a/nappletHost/src/main/kotlin/com/vitorpamplona/amethyst/napplethost/NappletHostActivity.kt b/nappletHost/src/main/kotlin/com/vitorpamplona/amethyst/napplethost/NappletHostActivity.kt
index 2a8aff28bf..1489bb987d 100644
--- a/nappletHost/src/main/kotlin/com/vitorpamplona/amethyst/napplethost/NappletHostActivity.kt
+++ b/nappletHost/src/main/kotlin/com/vitorpamplona/amethyst/napplethost/NappletHostActivity.kt
@@ -51,6 +51,7 @@ import android.widget.Toast
 import androidx.activity.ComponentActivity
 import androidx.activity.OnBackPressedCallback
 import androidx.core.content.ContextCompat
+import androidx.core.graphics.Insets
 import androidx.core.view.ViewCompat
 import androidx.core.view.WindowInsetsCompat
 import androidx.webkit.JavaScriptReplyProxy
@@ -229,9 +230,15 @@ class NappletHostActivity : ComponentActivity() {
         // Activities are edge-to-edge by default on recent Android; pad by the system bar and
         // display-cutout insets so neither the chrome nor the applet draws under the system bars.
         ViewCompat.setOnApplyWindowInsetsListener(root) { view, insets ->
-            val bars = insets.getInsets(WindowInsetsCompat.Type.systemBars() or WindowInsetsCompat.Type.displayCutout())
+            val applied = WindowInsetsCompat.Type.systemBars() or WindowInsetsCompat.Type.displayCutout()
+            val bars = insets.getInsets(applied)
             view.setPadding(bars.left, bars.top, bars.right, bars.bottom)
-            insets
+            // Zero the insets we just turned into padding before they reach the child WebView: on
+            // targetSdk 35+ the WebView auto-applies any insets it receives to its own web content, so
+            // leaving them un-consumed padded the bottom a SECOND time — a band of the page's own
+            // background above the navigation bar. Keep the other types (notably IME) flowing so the
+            // applet's keyboard-aware resize still works.
+            WindowInsetsCompat.Builder(insets).setInsets(applied, Insets.NONE).build()
         }
 
         probeAndMount()
@@ -375,6 +382,10 @@ class NappletHostActivity : ComponentActivity() {
                 safeBrowsingEnabled = true
             }
         }
+        // Disable the overscroll stretch/glow: forcing a scroll past the content edge stretched the
+        // WebView's output and exposed the shell document's background behind the applet iframe at the
+        // seam (a stray white band at the bottom). The applet's own content still scrolls normally.
+        webView.overScrollMode = View.OVER_SCROLL_NEVER
         WebView.setWebContentsDebuggingEnabled(false)
         webView.webViewClient = NappletWebViewClient()
     }