fix(ux): 10 UI/UX bugs from pre-release audit (toward no-bug launch gate)

Found via parallel screen audit; each confirmed in code:
- AuthGate: auto-prompt biometrics on lock (useEffect was imported but unused)
- CodeBlock: horizontal scroll for long code lines (were wrapped/mangled)
- DiffView: horizontal scroll instead of numberOfLines=1 truncation
- chat: biometric-cancel on send shows feedback instead of silently dropping msg
- chat: send failure restores input + attachments and alerts
- chat: removed dead /compact + /clear builtin commands (advertised, no-op)
- sessions: delete + rename failures alert instead of silent; rename guarded
  against double-submit
- sessions: onRefresh spinner no longer hangs forever if a refresh rejects
- add/edit connection: validate URL has http(s):// scheme before save/test

typecheck clean, 65/65 unit tests pass. Runtime UI behavior still needs on-device
verification per the pre-posting test gate (HANDOFF §0b).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/components/AuthGate.tsx

@@ -13,6 +13,16 @@ export function AuthGate({ children }: Props) {
 
   const { isAuthenticated, settings, hasBiometrics, biometricType, authenticate, error } = useAuth()
 
+  // Auto-prompt the OS biometric dialog once when the lock screen appears, so users
+  // aren't forced to tap "Unlock" on every cold start. If they cancel/fail, the
+  // manual "Unlock" button below is the fallback.
+  useEffect(() => {
+    if (settings.requireBiometric && hasBiometrics && !isAuthenticated) {
+      authenticate()
+    }
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [])
+
   // If biometric not required, or no biometrics available, show children
   if (!settings.requireBiometric || !hasBiometrics) {
     return <>{children}</>

src/components/chat/DiffView.tsx

@@ -1,4 +1,4 @@
-import { View, Text, StyleSheet, Platform } from "react-native"
+import { View, Text, StyleSheet, Platform, ScrollView } from "react-native"
 
 const mono = Platform.OS === "ios" ? "Menlo" : "monospace"
 
@@ -76,32 +76,35 @@ export function DiffView({ before, after, isDark }: Props) {
 
   return (
     <View style={[s.container, isDark && s.containerDark]}>
-      {lines.map((line, idx) => (
-        <View
-          key={idx}
-          style={[
-            s.line,
-            line.type === "add" && (isDark ? s.addDark : s.add),
-            line.type === "remove" && (isDark ? s.removeDark : s.remove),
-          ]}
-        >
-          <Text style={[s.prefix, isDark && s.prefixDark]}>
-            {line.type === "add" ? "+" : line.type === "remove" ? "-" : " "}
-          </Text>
-          <Text
-            style={[
-              s.text,
-              isDark && s.textDark,
-              line.type === "add" && s.addText,
-              line.type === "remove" && s.removeText,
-            ]}
-            selectable
-            numberOfLines={1}
-          >
-            {line.text}
-          </Text>
+      <ScrollView horizontal showsHorizontalScrollIndicator>
+        <View>
+          {lines.map((line, idx) => (
+            <View
+              key={idx}
+              style={[
+                s.line,
+                line.type === "add" && (isDark ? s.addDark : s.add),
+                line.type === "remove" && (isDark ? s.removeDark : s.remove),
+              ]}
+            >
+              <Text style={[s.prefix, isDark && s.prefixDark]}>
+                {line.type === "add" ? "+" : line.type === "remove" ? "-" : " "}
+              </Text>
+              <Text
+                style={[
+                  s.text,
+                  isDark && s.textDark,
+                  line.type === "add" && s.addText,
+                  line.type === "remove" && s.removeText,
+                ]}
+                selectable
+              >
+                {line.text}
+              </Text>
+            </View>
+          ))}
         </View>
-      ))}
+      </ScrollView>
     </View>
   )
 }
@@ -135,7 +138,6 @@ const s = StyleSheet.create({
   prefixDark: { color: "#666666" },
 
   text: {
-    flex: 1,
     fontSize: 12,
     fontFamily: mono,
     color: "#0a0a0a",

src/components/markdown/CodeBlock.tsx

@@ -1,5 +1,5 @@
 import { useState } from "react"
-import { View, Text, TouchableOpacity, StyleSheet, useColorScheme, Platform } from "react-native"
+import { View, Text, TouchableOpacity, StyleSheet, useColorScheme, Platform, ScrollView } from "react-native"
 import * as Clipboard from "expo-clipboard"
 
 interface Props {
@@ -27,9 +27,11 @@ export function CodeBlock({ code, language }: Props) {
           <Text style={[styles.copyBtn, isDark && styles.copyBtnDark]}>{copied ? "Copied!" : "Copy"}</Text>
         </TouchableOpacity>
       </View>
-      <Text style={[styles.code, isDark && styles.codeDark]} selectable>
-        {code}
-      </Text>
+      <ScrollView horizontal showsHorizontalScrollIndicator contentContainerStyle={styles.codeScroll}>
+        <Text style={[styles.code, isDark && styles.codeDark]} selectable>
+          {code}
+        </Text>
+      </ScrollView>
     </View>
   )
 }
@@ -72,12 +74,14 @@ const styles = StyleSheet.create({
   copyBtnDark: {
     color: "#a78bfa",
   },
+  codeScroll: {
+    padding: 12,
+  },
   code: {
     fontFamily: Platform.OS === "ios" ? "Menlo" : "monospace",
     fontSize: 13,
     lineHeight: 20,
     color: "#1a1a1a",
-    padding: 12,
   },
   codeDark: {
     color: "#e5e5e5",