diff --git a/fuzz/.gitignore b/fuzz/.gitignore
new file mode 100644
index 0000000..1a45eee
--- /dev/null
+++ b/fuzz/.gitignore
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new file mode 100644
index 0000000..2448438
--- /dev/null
+++ b/fuzz/Cargo.lock
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diff --git a/fuzz/Cargo.toml b/fuzz/Cargo.toml
new file mode 100644
index 0000000..af8bedd
--- /dev/null
+++ b/fuzz/Cargo.toml
@@ -0,0 +1,42 @@
+[package]
+name = "nescript-fuzz"
+version = "0.0.0"
+publish = false
+edition = "2021"
+
+[package.metadata]
+cargo-fuzz = true
+
+[dependencies]
+libfuzzer-sys = "0.4"
+
+[dependencies.nescript]
+path = ".."
+
+[[bin]]
+name = "fuzz_target_1"
+path = "fuzz_targets/fuzz_target_1.rs"
+test = false
+doc = false
+bench = false
+
+[[bin]]
+name = "fuzz_lexer"
+path = "fuzz_targets/fuzz_lexer.rs"
+test = false
+doc = false
+bench = false
+
+[[bin]]
+name = "fuzz_parser"
+path = "fuzz_targets/fuzz_parser.rs"
+test = false
+doc = false
+bench = false
+
+[[bin]]
+name = "fuzz_compile"
+path = "fuzz_targets/fuzz_compile.rs"
+test = false
+doc = false
+bench = false
diff --git a/fuzz/fuzz_targets/fuzz_compile.rs b/fuzz/fuzz_targets/fuzz_compile.rs
new file mode 100644
index 0000000..2724992
--- /dev/null
+++ b/fuzz/fuzz_targets/fuzz_compile.rs
@@ -0,0 +1,33 @@
+#![no_main]
+
+use libfuzzer_sys::fuzz_target;
+
+fuzz_target!(|data: &[u8]| {
+    // The full compilation pipeline must never panic — errors are reported
+    // via diagnostics, not panics.
+    if let Ok(source) = std::str::from_utf8(data) {
+        let (program, parse_diags) = nescript::parser::parse(source);
+        if parse_diags.iter().any(|d| d.is_error()) {
+            return;
+        }
+        let Some(program) = program else { return };
+
+        let analysis = nescript::analyzer::analyze(&program);
+        if analysis.diagnostics.iter().any(|d| d.is_error()) {
+            return;
+        }
+
+        // IR lowering + optimization
+        let mut ir = nescript::ir::lower(&program, &analysis);
+        nescript::optimizer::optimize(&mut ir);
+
+        // Codegen + assembly
+        let codegen =
+            nescript::codegen::CodeGen::new(&analysis.var_allocations, &program.constants);
+        let instructions = codegen.generate(&program);
+
+        // Linking
+        let linker = nescript::linker::Linker::new(program.game.mirroring);
+        let _rom = linker.link(&instructions);
+    }
+});
diff --git a/fuzz/fuzz_targets/fuzz_lexer.rs b/fuzz/fuzz_targets/fuzz_lexer.rs
new file mode 100644
index 0000000..53f803f
--- /dev/null
+++ b/fuzz/fuzz_targets/fuzz_lexer.rs
@@ -0,0 +1,10 @@
+#![no_main]
+
+use libfuzzer_sys::fuzz_target;
+
+fuzz_target!(|data: &[u8]| {
+    // The lexer must never panic on any input — always produce tokens or errors.
+    if let Ok(source) = std::str::from_utf8(data) {
+        let _ = nescript::lexer::lex(source);
+    }
+});
diff --git a/fuzz/fuzz_targets/fuzz_parser.rs b/fuzz/fuzz_targets/fuzz_parser.rs
new file mode 100644
index 0000000..f4182b6
--- /dev/null
+++ b/fuzz/fuzz_targets/fuzz_parser.rs
@@ -0,0 +1,10 @@
+#![no_main]
+
+use libfuzzer_sys::fuzz_target;
+
+fuzz_target!(|data: &[u8]| {
+    // The parser must never panic — always produce an AST or diagnostics.
+    if let Ok(source) = std::str::from_utf8(data) {
+        let _ = nescript::parser::parse(source);
+    }
+});
diff --git a/fuzz/fuzz_targets/fuzz_target_1.rs b/fuzz/fuzz_targets/fuzz_target_1.rs
new file mode 100644
index 0000000..43a88c1
--- /dev/null
+++ b/fuzz/fuzz_targets/fuzz_target_1.rs
@@ -0,0 +1,7 @@
+#![no_main]
+
+use libfuzzer_sys::fuzz_target;
+
+fuzz_target!(|data: &[u8]| {
+    // fuzzed code goes here
+});
diff --git a/src/parser/tests.rs b/src/parser/tests.rs
index 9505467..4b4992a 100644
--- a/src/parser/tests.rs
+++ b/src/parser/tests.rs
@@ -678,3 +678,240 @@ fn parse_bank_decl() {
     assert_eq!(prog.banks[0].name, "Level1Data");
     assert_eq!(prog.banks[0].bank_type, BankType::Prg);
 }
+
+// ── Edge cases and regression tests ──
+
+#[test]
+fn draw_followed_by_statement() {
+    // Regression: draw keyword-arg parser used to consume the next statement's
+    // identifier as a keyword arg, causing "expected ':'" errors.
+    let src = r#"
+        game "T" { mapper: NROM }
+        var i: u8 = 0
+        on frame {
+            draw Sprite at: (0, 0)
+            i += 1
+        }
+        start Main
+    "#;
+    let prog = parse_ok(src);
+    let frame = prog.states[0].on_frame.as_ref().unwrap();
+    assert_eq!(frame.statements.len(), 2); // draw + assignment
+}
+
+#[test]
+fn draw_with_frame_followed_by_statement() {
+    let src = r#"
+        game "T" { mapper: NROM }
+        var x: u8 = 0
+        on frame {
+            draw Sprite at: (0, 0) frame: 1
+            x = 5
+        }
+        start Main
+    "#;
+    let prog = parse_ok(src);
+    let frame = prog.states[0].on_frame.as_ref().unwrap();
+    assert_eq!(frame.statements.len(), 2);
+}
+
+#[test]
+fn nested_if_else_chain() {
+    let src = r#"
+        game "T" { mapper: NROM }
+        var x: u8 = 0
+        on frame {
+            if x == 0 {
+                x = 1
+            } else if x == 1 {
+                x = 2
+            } else if x == 2 {
+                x = 3
+            } else {
+                x = 0
+            }
+        }
+        start Main
+    "#;
+    let prog = parse_ok(src);
+    let frame = prog.states[0].on_frame.as_ref().unwrap();
+    match &frame.statements[0] {
+        Statement::If(_, _, else_ifs, else_block, _) => {
+            assert_eq!(else_ifs.len(), 2);
+            assert!(else_block.is_some());
+        }
+        other => panic!("expected If, got {other:?}"),
+    }
+}
+
+#[test]
+fn deeply_nested_blocks() {
+    let src = r#"
+        game "T" { mapper: NROM }
+        var x: u8 = 0
+        on frame {
+            if x == 0 {
+                if x == 0 {
+                    if x == 0 {
+                        if x == 0 {
+                            x = 1
+                        }
+                    }
+                }
+            }
+        }
+        start Main
+    "#;
+    parse_ok(src); // should not stack overflow
+}
+
+#[test]
+fn empty_function_body() {
+    let src = r#"
+        game "T" { mapper: NROM }
+        fun noop() {}
+        on frame { wait_frame }
+        start Main
+    "#;
+    let prog = parse_ok(src);
+    assert_eq!(prog.functions.len(), 1);
+    assert!(prog.functions[0].body.statements.is_empty());
+}
+
+#[test]
+fn empty_state_handlers() {
+    let src = r#"
+        game "T" { mapper: NROM }
+        state Main {
+            on enter {}
+            on exit {}
+            on frame {}
+        }
+        start Main
+    "#;
+    let prog = parse_ok(src);
+    assert!(prog.states[0]
+        .on_enter
+        .as_ref()
+        .unwrap()
+        .statements
+        .is_empty());
+    assert!(prog.states[0]
+        .on_exit
+        .as_ref()
+        .unwrap()
+        .statements
+        .is_empty());
+    assert!(prog.states[0]
+        .on_frame
+        .as_ref()
+        .unwrap()
+        .statements
+        .is_empty());
+}
+
+#[test]
+fn button_start_in_condition() {
+    // "start" is a keyword but valid as a button name
+    let src = r#"
+        game "T" { mapper: NROM }
+        on frame {
+            if button.start { wait_frame }
+        }
+        start Main
+    "#;
+    let prog = parse_ok(src);
+    let frame = prog.states[0].on_frame.as_ref().unwrap();
+    match &frame.statements[0] {
+        Statement::If(Expr::ButtonRead(_, button, _), _, _, _, _) => {
+            assert_eq!(button, "start");
+        }
+        other => panic!("expected if with button.start, got {other:?}"),
+    }
+}
+
+#[test]
+fn button_select_in_condition() {
+    let src = r#"
+        game "T" { mapper: NROM }
+        on frame {
+            if button.select { wait_frame }
+        }
+        start Main
+    "#;
+    parse_ok(src); // "select" is a keyword too — must parse as button name
+}
+
+#[test]
+fn multiple_draws_in_sequence() {
+    let src = r#"
+        game "T" { mapper: NROM }
+        var x: u8 = 0
+        on frame {
+            draw A at: (0, 0)
+            draw B at: (10, 10)
+            draw C at: (20, 20)
+            x += 1
+        }
+        start Main
+    "#;
+    let prog = parse_ok(src);
+    let frame = prog.states[0].on_frame.as_ref().unwrap();
+    assert_eq!(frame.statements.len(), 4); // 3 draws + 1 assignment
+}
+
+#[test]
+fn parser_no_panic_on_garbage() {
+    // The parser should never panic, only return errors.
+    let garbage_inputs = [
+        "",
+        "{}{}{}",
+        "game",
+        "game \"\"",
+        "game \"\" {",
+        "game \"\" { mapper: }",
+        "var : = 0",
+        "fun () {}",
+        "if if if",
+        "while { }",
+        "draw",
+        "draw X",
+        "draw X at:",
+        "draw X at: (",
+        "draw X at: (0",
+        "draw X at: (0,",
+        "draw X at: (0, 0",
+        "sprite {",
+        "palette { colors: }",
+        "[[[",
+        "))))",
+        "0x 0b",
+        "\"unterminated",
+        "/* no block comments */",
+        "!@#$%",
+        &"x ".repeat(1000), // long input
+    ];
+    for input in &garbage_inputs {
+        let _ = parse(input); // must not panic
+    }
+}
+
+#[test]
+fn lexer_no_panic_on_garbage() {
+    use crate::lexer::lex;
+    let garbage_inputs = [
+        "\0\0\0",
+        "\x01\x02\x03",
+        "\"\\",
+        "0x",
+        "0b",
+        "99999999999999999999",
+        "0xFFFFFFFFFF",
+        &"a".repeat(10000),
+        "!!!!!!",
+        "\t\r\n \t\r\n",
+    ];
+    for input in &garbage_inputs {
+        let _ = lex(input); // must not panic
+    }
+}