diff --git a/crates/prometeu-compiler/src/frontends/pbs/collector.rs b/crates/prometeu-compiler/src/frontends/pbs/collector.rs
index f999d1cc..ebf22ac2 100644
--- a/crates/prometeu-compiler/src/frontends/pbs/collector.rs
+++ b/crates/prometeu-compiler/src/frontends/pbs/collector.rs
@@ -47,6 +47,7 @@ impl SymbolCollector {
             namespace: Namespace::Value,
             visibility: Visibility::FilePrivate,
             ty: None, // Will be resolved later
+            is_host: false,
             span: decl.span,
         };
         self.insert_value_symbol(symbol);
@@ -64,6 +65,7 @@ impl SymbolCollector {
             namespace: Namespace::Type, // Service is a type
             visibility: vis,
             ty: None,
+            is_host: false,
             span: decl.span,
         };
         self.insert_type_symbol(symbol);
@@ -87,6 +89,7 @@ impl SymbolCollector {
             namespace: Namespace::Type,
             visibility: vis,
             ty: None,
+            is_host: decl.is_host,
             span: decl.span,
         };
         self.insert_type_symbol(symbol);
diff --git a/crates/prometeu-compiler/src/frontends/pbs/contracts.rs b/crates/prometeu-compiler/src/frontends/pbs/contracts.rs
index 542a3971..ab7b858f 100644
--- a/crates/prometeu-compiler/src/frontends/pbs/contracts.rs
+++ b/crates/prometeu-compiler/src/frontends/pbs/contracts.rs
@@ -61,6 +61,26 @@ impl ContractRegistry {
         log.insert("writeTag".to_string(), 0x5002);
         mappings.insert("Log".to_string(), log);
 
+        // System mappings
+        let mut system = HashMap::new();
+        system.insert("hasCart".to_string(), 0x0001);
+        system.insert("runCart".to_string(), 0x0002);
+        mappings.insert("System".to_string(), system);
+
+        // Asset mappings
+        let mut asset = HashMap::new();
+        asset.insert("load".to_string(), 0x6001);
+        asset.insert("status".to_string(), 0x6002);
+        asset.insert("commit".to_string(), 0x6003);
+        asset.insert("cancel".to_string(), 0x6004);
+        mappings.insert("Asset".to_string(), asset);
+
+        // Bank mappings
+        let mut bank = HashMap::new();
+        bank.insert("info".to_string(), 0x6101);
+        bank.insert("slotInfo".to_string(), 0x6102);
+        mappings.insert("Bank".to_string(), bank);
+
         Self { mappings }
     }
 
diff --git a/crates/prometeu-compiler/src/frontends/pbs/lowering.rs b/crates/prometeu-compiler/src/frontends/pbs/lowering.rs
index b3982730..53911326 100644
--- a/crates/prometeu-compiler/src/frontends/pbs/lowering.rs
+++ b/crates/prometeu-compiler/src/frontends/pbs/lowering.rs
@@ -7,7 +7,7 @@ use crate::ir_core::{Block, Function, Instr, Module, Param, Program, Terminator,
 use std::collections::HashMap;
 
 pub struct Lowerer<'a> {
-    _module_symbols: &'a ModuleSymbols,
+    module_symbols: &'a ModuleSymbols,
     program: Program,
     current_function: Option<Function>,
     current_block: Option<Block>,
@@ -21,7 +21,7 @@ pub struct Lowerer<'a> {
 impl<'a> Lowerer<'a> {
     pub fn new(module_symbols: &'a ModuleSymbols) -> Self {
         Self {
-            _module_symbols: module_symbols,
+            module_symbols,
             program: Program {
                 const_pool: ir_core::ConstPool::new(),
                 modules: Vec::new(),
@@ -224,16 +224,25 @@ impl<'a> Lowerer<'a> {
             }
             Node::MemberAccess(ma) => {
                 if let Node::Ident(obj_id) = &*ma.object {
-                    if let Some(syscall_id) = self.contract_registry.resolve(&obj_id.name, &ma.member) {
-                        self.emit(Instr::Syscall(syscall_id));
-                    } else {
-                        // Regular member call (method)
-                        // In v0 we don't handle this yet, so emit dummy call
-                        self.emit(Instr::Call(FunctionId(0), n.args.len() as u32));
+                    // Check if it's a host contract according to symbol table
+                    let is_host_contract = self.module_symbols.type_symbols.get(&obj_id.name)
+                        .map(|sym| sym.kind == SymbolKind::Contract && sym.is_host)
+                        .unwrap_or(false);
+                    
+                    // Ensure it's not shadowed by a local variable
+                    let is_shadowed = self.lookup_local(&obj_id.name).is_some();
+
+                    if is_host_contract && !is_shadowed {
+                        if let Some(syscall_id) = self.contract_registry.resolve(&obj_id.name, &ma.member) {
+                            self.emit(Instr::Syscall(syscall_id));
+                            return;
+                        }
                     }
-                } else {
-                    self.emit(Instr::Call(FunctionId(0), n.args.len() as u32));
                 }
+                
+                // Regular member call (method) or fallback
+                // In v0 we don't handle this yet, so emit dummy call
+                self.emit(Instr::Call(FunctionId(0), n.args.len() as u32));
             }
             _ => {
                 self.emit(Instr::Call(FunctionId(0), n.args.len() as u32));
diff --git a/crates/prometeu-compiler/src/frontends/pbs/resolver.rs b/crates/prometeu-compiler/src/frontends/pbs/resolver.rs
index c0b931e8..5dbb469a 100644
--- a/crates/prometeu-compiler/src/frontends/pbs/resolver.rs
+++ b/crates/prometeu-compiler/src/frontends/pbs/resolver.rs
@@ -171,9 +171,17 @@ impl<'a> Resolver<'a> {
                 self.exit_scope();
             }
             Node::MemberAccess(n) => {
-                self.resolve_node(&n.object);
-                // For member access, the member name itself isn't resolved in the value namespace
-                // unless it's a property. In v0, we mostly care about host calls.
+                if let Node::Ident(id) = &*n.object {
+                    if self.lookup_identifier(&id.name, Namespace::Value).is_none() {
+                        // If not found in Value namespace, try Type namespace (for Contracts/Services)
+                        if self.lookup_identifier(&id.name, Namespace::Type).is_none() {
+                            // Still not found, use resolve_identifier to report error in Value namespace
+                            self.resolve_identifier(&id.name, id.span, Namespace::Value);
+                        }
+                    }
+                } else {
+                    self.resolve_node(&n.object);
+                }
             }
             _ => {}
         }
@@ -235,21 +243,41 @@ impl<'a> Resolver<'a> {
     }
 
     fn resolve_identifier(&mut self, name: &str, span: Span, namespace: Namespace) -> Option<Symbol> {
-        // Built-ins (minimal for v0)
-        if namespace == Namespace::Type {
-            match name {
-                "int" | "float" | "string" | "bool" | "void" | "optional" | "result" => return None,
-                _ => {}
-            }
+        if self.is_builtin(name, namespace) {
+            return None;
         }
 
-        if namespace == Namespace::Value {
-            match name {
-                "none" | "some" | "ok" | "err" | "true" | "false" => return None,
-                _ => {}
+        if let Some(sym) = self.lookup_identifier(name, namespace) {
+            Some(sym)
+        } else {
+            if namespace == Namespace::Type {
+                self.diagnostics.push(Diagnostic {
+                    level: DiagnosticLevel::Error,
+                    code: Some("E_TYPE_UNKNOWN_TYPE".to_string()),
+                    message: format!("Unknown type: {}", name),
+                    span: Some(span),
+                });
+            } else {
+                self.error_undefined(name, span);
             }
+            None
         }
+    }
 
+    fn is_builtin(&self, name: &str, namespace: Namespace) -> bool {
+        match namespace {
+            Namespace::Type => match name {
+                "int" | "float" | "string" | "bool" | "void" | "optional" | "result" => true,
+                _ => false,
+            },
+            Namespace::Value => match name {
+                "none" | "some" | "ok" | "err" | "true" | "false" => true,
+                _ => false,
+            },
+        }
+    }
+
+    fn lookup_identifier(&self, name: &str, namespace: Namespace) -> Option<Symbol> {
         // 1. local bindings
         if namespace == Namespace::Value {
             for scope in self.scopes.iter().rev() {
@@ -280,16 +308,6 @@ impl<'a> Resolver<'a> {
             return Some(sym.clone());
         }
 
-        if namespace == Namespace::Type {
-            self.diagnostics.push(Diagnostic {
-                level: DiagnosticLevel::Error,
-                code: Some("E_TYPE_UNKNOWN_TYPE".to_string()),
-                message: format!("Unknown type: {}", name),
-                span: Some(span),
-            });
-        } else {
-            self.error_undefined(name, span);
-        }
         None
     }
 
@@ -323,6 +341,7 @@ impl<'a> Resolver<'a> {
                 namespace: Namespace::Value,
                 visibility: Visibility::FilePrivate,
                 ty: None, // Will be set by TypeChecker
+                is_host: false,
                 span,
             });
         }
diff --git a/crates/prometeu-compiler/src/frontends/pbs/symbols.rs b/crates/prometeu-compiler/src/frontends/pbs/symbols.rs
index a29097ea..b5c4b03c 100644
--- a/crates/prometeu-compiler/src/frontends/pbs/symbols.rs
+++ b/crates/prometeu-compiler/src/frontends/pbs/symbols.rs
@@ -19,7 +19,7 @@ pub enum SymbolKind {
     Local,
 }
 
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum Namespace {
     Type,
     Value,
@@ -32,6 +32,7 @@ pub struct Symbol {
     pub namespace: Namespace,
     pub visibility: Visibility,
     pub ty: Option<PbsType>,
+    pub is_host: bool,
     pub span: Span,
 }
 
diff --git a/crates/prometeu-compiler/src/frontends/pbs/typecheck.rs b/crates/prometeu-compiler/src/frontends/pbs/typecheck.rs
index bf847704..896b217a 100644
--- a/crates/prometeu-compiler/src/frontends/pbs/typecheck.rs
+++ b/crates/prometeu-compiler/src/frontends/pbs/typecheck.rs
@@ -4,6 +4,7 @@ use crate::frontends::pbs::ast::*;
 use crate::frontends::pbs::symbols::*;
 use crate::frontends::pbs::types::PbsType;
 use crate::frontends::pbs::resolver::ModuleProvider;
+use crate::frontends::pbs::contracts::ContractRegistry;
 use std::collections::HashMap;
 
 pub struct TypeChecker<'a> {
@@ -13,6 +14,7 @@ pub struct TypeChecker<'a> {
     mut_bindings: Vec<HashMap<String, bool>>,
     current_return_type: Option<PbsType>,
     diagnostics: Vec<Diagnostic>,
+    contract_registry: ContractRegistry,
 }
 
 impl<'a> TypeChecker<'a> {
@@ -27,6 +29,7 @@ impl<'a> TypeChecker<'a> {
             mut_bindings: Vec::new(),
             current_return_type: None,
             diagnostics: Vec::new(),
+            contract_registry: ContractRegistry::new(),
         }
     }
 
@@ -140,6 +143,24 @@ impl<'a> TypeChecker<'a> {
     }
 
     fn check_member_access(&mut self, n: &MemberAccessNode) -> PbsType {
+        if let Node::Ident(id) = &*n.object {
+            // Check if it's a known host contract
+            if let Some(sym) = self.module_symbols.type_symbols.get(&id.name) {
+                if sym.kind == SymbolKind::Contract && sym.is_host {
+                    // Check if the method exists in registry
+                    if self.contract_registry.resolve(&id.name, &n.member).is_none() {
+                        self.diagnostics.push(Diagnostic {
+                            level: DiagnosticLevel::Error,
+                            code: Some("E_RESOLVE_UNDEFINED".to_string()),
+                            message: format!("Method '{}' not found on host contract '{}'", n.member, id.name),
+                            span: Some(n.span),
+                        });
+                    }
+                    return PbsType::Void;
+                }
+            }
+        }
+
         let _obj_ty = self.check_node(&n.object);
         // For v0, we assume member access on a host contract is valid and return a dummy type
         // or resolve it if we have contract info.
diff --git a/crates/prometeu-compiler/tests/pbs_contract_tests.rs b/crates/prometeu-compiler/tests/pbs_contract_tests.rs
index 73a51d6e..b160345b 100644
--- a/crates/prometeu-compiler/tests/pbs_contract_tests.rs
+++ b/crates/prometeu-compiler/tests/pbs_contract_tests.rs
@@ -7,6 +7,8 @@ use prometeu_compiler::ir_core;
 #[test]
 fn test_host_contract_call_lowering() {
     let code = "
+        declare contract Gfx host {}
+        declare contract Log host {}
         fn main() {
             Gfx.clear(0);
             Log.write(\"Hello\");
@@ -31,9 +33,61 @@ fn test_host_contract_call_lowering() {
     assert!(instrs.iter().any(|i| matches!(i, ir_core::Instr::Syscall(0x5001))));
 }
 
+#[test]
+fn test_contract_call_without_host_lowering() {
+    let code = "
+        declare contract Gfx {}
+        fn main() {
+            Gfx.clear(0);
+        }
+    ";
+    let mut parser = Parser::new(code, 0);
+    let ast = parser.parse_file().expect("Failed to parse");
+
+    let mut collector = SymbolCollector::new();
+    let (type_symbols, value_symbols) = collector.collect(&ast).expect("Failed to collect symbols");
+    let module_symbols = ModuleSymbols { type_symbols, value_symbols };
+
+    let lowerer = Lowerer::new(&module_symbols);
+    let program = lowerer.lower_file(&ast, "test");
+
+    let func = &program.modules[0].functions[0];
+    let instrs: Vec<_> = func.blocks.iter().flat_map(|b| b.instrs.iter()).collect();
+    
+    // Should NOT be a syscall if not declared as host
+    assert!(!instrs.iter().any(|i| matches!(i, ir_core::Instr::Syscall(_))));
+}
+
+#[test]
+fn test_shadowed_contract_call_lowering() {
+    let code = "
+        declare contract Gfx host {}
+        fn main() {
+            let Gfx = 10;
+            Gfx.clear(0);
+        }
+    ";
+    let mut parser = Parser::new(code, 0);
+    let ast = parser.parse_file().expect("Failed to parse");
+
+    let mut collector = SymbolCollector::new();
+    let (type_symbols, value_symbols) = collector.collect(&ast).expect("Failed to collect symbols");
+    let module_symbols = ModuleSymbols { type_symbols, value_symbols };
+
+    let lowerer = Lowerer::new(&module_symbols);
+    let program = lowerer.lower_file(&ast, "test");
+
+    let func = &program.modules[0].functions[0];
+    let instrs: Vec<_> = func.blocks.iter().flat_map(|b| b.instrs.iter()).collect();
+    
+    // Should NOT be a syscall because Gfx is shadowed by a local
+    assert!(!instrs.iter().any(|i| matches!(i, ir_core::Instr::Syscall(_))));
+}
+
 #[test]
 fn test_invalid_contract_call_lowering() {
     let code = "
+        declare contract Gfx host {}
         fn main() {
             Gfx.invalidMethod(0);
         }
diff --git a/crates/prometeu-compiler/tests/pbs_resolver_tests.rs b/crates/prometeu-compiler/tests/pbs_resolver_tests.rs
index 468dcde3..ed230404 100644
--- a/crates/prometeu-compiler/tests/pbs_resolver_tests.rs
+++ b/crates/prometeu-compiler/tests/pbs_resolver_tests.rs
@@ -116,6 +116,7 @@ fn test_visibility_error() {
         namespace: Namespace::Type,
         visibility: Visibility::FilePrivate,
         ty: None,
+        is_host: false,
         span: Span::new(1, 0, 0),
     }).unwrap();
     
@@ -160,6 +161,7 @@ fn test_import_resolution() {
         namespace: Namespace::Type,
         visibility: Visibility::Pub,
         ty: None,
+        is_host: false,
         span: Span::new(1, 0, 0),
     }).unwrap();
     
diff --git a/crates/prometeu-compiler/tests/pbs_typecheck_tests.rs b/crates/prometeu-compiler/tests/pbs_typecheck_tests.rs
index 15a5bef2..66d8c4aa 100644
--- a/crates/prometeu-compiler/tests/pbs_typecheck_tests.rs
+++ b/crates/prometeu-compiler/tests/pbs_typecheck_tests.rs
@@ -18,7 +18,9 @@ fn check_code(code: &str) -> Result<(), String> {
                 let code = diag.code.unwrap_or_else(|| "NO_CODE".to_string());
                 errors.push(format!("{}: {}", code, diag.message));
             }
-            Err(errors.join(", "))
+            let err_msg = errors.join(", ");
+            println!("Compilation failed: {}", err_msg);
+            Err(err_msg)
         }
     }
 }
@@ -101,6 +103,31 @@ fn test_unknown_type() {
     assert!(res.unwrap_err().contains("E_TYPE_UNKNOWN_TYPE"));
 }
 
+#[test]
+fn test_invalid_host_method() {
+    let code = "
+        declare contract Gfx host {}
+        fn main() {
+            Gfx.invalidMethod();
+        }
+    ";
+    let res = check_code(code);
+    assert!(res.is_err());
+    assert!(res.unwrap_err().contains("E_RESOLVE_UNDEFINED"));
+}
+
+#[test]
+fn test_valid_host_method() {
+    let code = "
+        declare contract Gfx host {}
+        fn main() {
+            Gfx.clear(0);
+        }
+    ";
+    let res = check_code(code);
+    assert!(res.is_ok());
+}
+
 #[test]
 fn test_void_return_ok() {
     let code = "fn main() { return; }";