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>

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.")
+            }
           },
         },
       ])

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, {

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(

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.