diff --git a/app/(tabs)/index.tsx b/app/(tabs)/index.tsx
index 2800a34..facc4f5 100644
--- a/app/(tabs)/index.tsx
+++ b/app/(tabs)/index.tsx
@@ -111,6 +111,7 @@ export default function SessionsScreen() {
   const [isCreating, setIsCreating] = useState(false)
   const [renaming, setRenaming] = useState<Session | null>(null)
   const [renameText, setRenameText] = useState("")
+  const renamingInFlight = useRef(false)
 
   const { sessions, isLoading, error, loadSessions, createSession, deleteSession } = useSessions()
   const {
@@ -149,9 +150,14 @@ export default function SessionsScreen() {
 
   const onRefresh = useCallback(async () => {
     setRefreshing(true)
-    await Promise.all([loadSessions(), refreshProject()])
-    setRefreshing(false)
-  }, [])
+    try {
+      await Promise.all([loadSessions(), refreshProject()])
+    } catch (err) {
+      console.error("Refresh failed:", err)
+    } finally {
+      setRefreshing(false)
+    }
+  }, [loadSessions, refreshProject])
 
   const handleRename = useCallback((session: Session) => {
     setRenameText(session.title || "")
@@ -160,13 +166,21 @@ export default function SessionsScreen() {
 
   const submitRename = useCallback(async () => {
     const title = renameText.trim()
-    if (!title || !renaming) return
+    if (!title || !renaming || renamingInFlight.current) return
     const renameClient = renaming.directory ? (clientForDirectory(renaming.directory) ?? client) : client
     if (!renameClient) return
-    await renameClient.session.update(renaming.id, { title })
-    setRenaming(null)
-    setRenameText("")
-    loadSessions()
+    renamingInFlight.current = true
+    try {
+      await renameClient.session.update(renaming.id, { title })
+      setRenaming(null)
+      setRenameText("")
+      loadSessions()
+    } catch (err) {
+      console.error("Rename failed:", err)
+      Alert.alert("Rename failed", "Could not rename the session. Please try again.")
+    } finally {
+      renamingInFlight.current = false
+    }
   }, [renaming, renameText, client, clientForDirectory, loadSessions])
 
   const handleDelete = useCallback(
@@ -177,7 +191,12 @@ export default function SessionsScreen() {
           text: "Delete",
           style: "destructive",
           onPress: async () => {
-            await deleteSession(session.id)
+            try {
+              await deleteSession(session.id)
+            } catch (err) {
+              console.error("Delete failed:", err)
+              Alert.alert("Delete failed", "Could not delete the session. Please try again.")
+            }
           },
         },
       ])
diff --git a/app/connection/[id].tsx b/app/connection/[id].tsx
index 2839dad..73bd9b4 100644
--- a/app/connection/[id].tsx
+++ b/app/connection/[id].tsx
@@ -16,6 +16,7 @@ import { useConnections } from "../../src/stores/connections"
 import type { ConnectionType } from "../../src/lib/types"
 import { probeConnection, shareReport } from "../../src/lib/diagnostics"
 import { captureDiagnostic } from "../../src/lib/sentry"
+import { parseUrl } from "../../src/lib/diagnostics-classify"
 
 const CONNECTION_TYPES: Array<{
   type: ConnectionType
@@ -68,6 +69,10 @@ export default function EditConnectionScreen() {
       Alert.alert("Error", "Please enter a server URL")
       return
     }
+    if (!parseUrl(url).valid) {
+      Alert.alert("Invalid URL", "Enter a full URL including http:// or https://, e.g. http://192.168.1.100:4096")
+      return
+    }
 
     setIsTesting(true)
     const result = await testConnection(
@@ -111,6 +116,10 @@ export default function EditConnectionScreen() {
       Alert.alert("Error", "Please enter a server URL")
       return
     }
+    if (!parseUrl(url).valid) {
+      Alert.alert("Invalid URL", "Enter a full URL including http:// or https://, e.g. http://192.168.1.100:4096")
+      return
+    }
 
     setIsSaving(true)
     await updateConnection(connection.id, {
diff --git a/app/connection/add.tsx b/app/connection/add.tsx
index 3ae2e9f..d07228b 100644
--- a/app/connection/add.tsx
+++ b/app/connection/add.tsx
@@ -17,6 +17,7 @@ import { useConnections } from "../../src/stores/connections"
 import type { ConnectionType } from "../../src/lib/types"
 import { probeConnection, shareReport } from "../../src/lib/diagnostics"
 import { captureDiagnostic } from "../../src/lib/sentry"
+import { parseUrl } from "../../src/lib/diagnostics-classify"
 
 export default function AddConnectionScreen() {
   const colorScheme = useColorScheme()
@@ -121,6 +122,10 @@ export default function AddConnectionScreen() {
       Alert.alert("Error", "Please enter a server URL")
       return
     }
+    if (!parseUrl(url).valid) {
+      Alert.alert("Invalid URL", "Enter a full URL including http:// or https://, e.g. http://192.168.1.100:4096")
+      return
+    }
 
     setIsConnecting(true)
     await addConnection(
diff --git a/app/session/[id].tsx b/app/session/[id].tsx
index 192320f..41a3c78 100644
--- a/app/session/[id].tsx
+++ b/app/session/[id].tsx
@@ -61,14 +61,6 @@ const BUILTIN_COMMANDS: SlashCommand[] = [
     icon: "person-outline",
     type: "builtin",
   },
-  {
-    trigger: "compact",
-    title: "Compact",
-    description: "Summarize conversation",
-    icon: "contract-outline",
-    type: "builtin",
-  },
-  { trigger: "clear", title: "Clear", description: "Clear the session", icon: "trash-outline", type: "builtin" },
 ]
 
 function getShortDir(dir?: string): string | null {
@@ -214,12 +206,6 @@ export default function SessionScreen() {
             setInput("")
             cycleAgent()
             return
-          case "compact":
-            setInput("")
-            return
-          case "clear":
-            setInput("")
-            return
         }
       }
       setInput(`/${cmd.trigger} `)
@@ -316,7 +302,10 @@ export default function SessionScreen() {
   const handleSend = async () => {
     if (!input.trim() && attachments.length === 0) return
     const authenticated = await authenticateForMessage()
-    if (!authenticated) return
+    if (!authenticated) {
+      Alert.alert("Authentication required", "Biometric authentication is required to send. Please try again.")
+      return
+    }
 
     const text = input.trim()
     const files = [...attachments]
@@ -343,7 +332,15 @@ export default function SessionScreen() {
 
     // Messages are queued server-side when the session is busy.
     // No need to abort - just send and it will be processed after current response.
-    await sendMessage(text, model || undefined, agent || undefined, files)
+    try {
+      await sendMessage(text, model || undefined, agent || undefined, files)
+    } catch (err) {
+      console.error("Send failed:", err)
+      // Restore the user's text and attachments so their input isn't lost.
+      setInput((prev) => (prev ? prev : text))
+      setAttachments((prev) => (prev.length ? prev : files))
+      Alert.alert("Message not sent", "Could not send your message. Check your connection and try again.")
+    }
   }
 
   // In inverted mode, offset 0 = bottom. Show scroll button when scrolled away from bottom.
diff --git a/src/components/AuthGate.tsx b/src/components/AuthGate.tsx
index db7e7a5..7e3a831 100644
--- a/src/components/AuthGate.tsx
+++ b/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}</>
diff --git a/src/components/chat/DiffView.tsx b/src/components/chat/DiffView.tsx
index 7209a99..b3ebe7b 100644
--- a/src/components/chat/DiffView.tsx
+++ b/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",
diff --git a/src/components/markdown/CodeBlock.tsx b/src/components/markdown/CodeBlock.tsx
index a7f529d..df2bd3f 100644
--- a/src/components/markdown/CodeBlock.tsx
+++ b/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",