added typeaheead and introspetion

DBSyn/DatabaseModel.swift

@@ -197,6 +197,21 @@ final class DatabaseModel: ObservableObject {
         let views: [String]
         let columnsByTable: [String: [IntrospectedColumn]]
     }
+    // Resolve USE statements from the editor buffer even before Run is pressed.
+    // The completion provider must not depend on navigator selection alone.
+    var completionDatabase: String {
+        let pattern = #"(?im)^\s*USE\s+`?([A-Za-z_][A-Za-z0-9_]*)`?\s*;?"#
+        if let regex = try? NSRegularExpression(pattern: pattern) {
+            let value = sql as NSString
+            let range = NSRange(location: 0, length: value.length)
+            if let match = regex.matches(in: sql, range: range).last,
+               match.numberOfRanges > 1 {
+                return value.substring(with: match.range(at: 1))
+            }
+        }
+        return selectedDatabase.isEmpty ? (selected?.database ?? "") : selectedDatabase
+    }
+
     @Published private(set) var introspections: [String: SchemaIntrospection] = [:]
     private let introspectionStorageKey = "DBSyn.introspection.snapshots.v2"
     private func persistIntrospections() {
@@ -581,6 +596,7 @@ final class DatabaseModel: ObservableObject {
                         selectedDatabase = usedSchema
                         // Metadata is cached in memory for native SQL completion.
                         loadTables(database: usedSchema)
+                        introspect(database: usedSchema)
                     }
                 }
                 if listingDatabases {