diff --git a/crates/oxide_cli/src/main.rs b/crates/oxide_cli/src/main.rs
index 627cdea1..59011273 100644
--- a/crates/oxide_cli/src/main.rs
+++ b/crates/oxide_cli/src/main.rs
@@ -1,3 +1,116 @@
-fn main() {
-    println!("OxideJS CLI - not yet implemented");
+use std::fs;
+use std::process::ExitCode;
+
+use ansi_term::Colour::Red;
+use clap::{Parser, Subcommand};
+use oxide_parser::Allocator;
+
+#[derive(Parser)]
+#[command(name = "oxide", version, about = "OxideJS - Rust JavaScript engine")]
+struct Cli {
+    #[command(subcommand)]
+    command: Option<Commands>,
+
+    #[arg(short, long, global = true)]
+    verbose: bool,
+
+    #[arg(short, long, global = true)]
+    quiet: bool,
+}
+
+#[derive(Subcommand)]
+enum Commands {
+    Eval { code: String },
+    Run { file: String },
+    Bench { suite: Option<String> },
+    Test { suite: Option<String> },
+}
+
+fn main() -> ExitCode {
+    let cli = Cli::parse();
+
+    match cli.command {
+        Some(Commands::Eval { code }) => eval(&code),
+        Some(Commands::Run { file }) => run(&file),
+        Some(Commands::Bench { .. }) => not_implemented("bench"),
+        Some(Commands::Test { .. }) => not_implemented("test"),
+        None => repl(),
+    }
+}
+
+fn eval(code: &str) -> ExitCode {
+    let allocator = Allocator::default();
+    match oxide_parser::parse(&allocator, code) {
+        Ok(program) => {
+            println!("{program:#?}");
+            ExitCode::SUCCESS
+        }
+        Err(errors) => {
+            for err in &errors {
+                eprintln!("{}", Red.paint(err.to_string()));
+            }
+            ExitCode::FAILURE
+        }
+    }
+}
+
+fn run(file: &str) -> ExitCode {
+    match fs::read_to_string(file) {
+        Ok(source) => eval(&source),
+        Err(err) => {
+            eprintln!("{}", Red.paint(format!("Cannot read {file}: {err}")));
+            ExitCode::FAILURE
+        }
+    }
+}
+
+fn repl() -> ExitCode {
+    use rustyline::error::ReadlineError;
+    use rustyline::DefaultEditor;
+
+    let mut rl = match DefaultEditor::new() {
+        Ok(editor) => editor,
+        Err(err) => {
+            eprintln!("{}", Red.paint(format!("Failed to start REPL: {err}")));
+            return ExitCode::FAILURE;
+        }
+    };
+
+    loop {
+        match rl.readline("oxide> ") {
+            Ok(line) => {
+                let trimmed = line.trim();
+                if trimmed.is_empty() {
+                    continue;
+                }
+                if trimmed == ".exit" || trimmed == ".quit" {
+                    println!("exit");
+                    return ExitCode::SUCCESS;
+                }
+                rl.add_history_entry(trimmed).ok();
+                eval(trimmed);
+            }
+            Err(ReadlineError::Interrupted) => {
+                println!("^C");
+                return ExitCode::SUCCESS;
+            }
+            Err(ReadlineError::Eof) => {
+                println!("exit");
+                return ExitCode::SUCCESS;
+            }
+            Err(err) => {
+                eprintln!("{}", Red.paint(format!("REPL error: {err}")));
+                return ExitCode::FAILURE;
+            }
+        }
+    }
+}
+
+fn not_implemented(command: &str) -> ExitCode {
+    use ansi_term::Colour::Yellow;
+    eprintln!(
+        "{}",
+        Yellow.paint(format!("'{command}' is not yet implemented"))
+    );
+    ExitCode::SUCCESS
 }
diff --git a/crates/oxide_cli/tests/cli_smoke.rs b/crates/oxide_cli/tests/cli_smoke.rs
new file mode 100644
index 00000000..30459e21
--- /dev/null
+++ b/crates/oxide_cli/tests/cli_smoke.rs
@@ -0,0 +1,64 @@
+use std::process::Command;
+
+#[test]
+fn eval_simple_expression() {
+    let output = Command::new("cargo")
+        .args(["run", "--", "eval", "1 + 2"])
+        .output()
+        .expect("failed to run oxide eval");
+
+    assert!(output.status.success(), "eval 1+2 should exit 0");
+    let stdout = String::from_utf8_lossy(&output.stdout);
+    assert!(
+        stdout.contains("Program"),
+        "output should contain AST node: {stdout}"
+    );
+}
+
+#[test]
+fn eval_syntax_error() {
+    let output = Command::new("cargo")
+        .args(["run", "--", "eval", "function("])
+        .output()
+        .expect("failed to run oxide eval");
+
+    assert!(
+        !output.status.success(),
+        "syntax error should exit non-zero"
+    );
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    assert!(
+        !stderr.is_empty(),
+        "syntax error should produce stderr output"
+    );
+}
+
+#[test]
+fn run_file() {
+    let fixture = concat!(env!("CARGO_MANIFEST_DIR"), "/tests/fixtures/hello.js");
+    let output = Command::new("cargo")
+        .args(["run", "--", "run", fixture])
+        .output()
+        .expect("failed to run oxide run");
+
+    assert!(output.status.success(), "run hello.js should exit 0");
+    let stdout = String::from_utf8_lossy(&output.stdout);
+    assert!(
+        stdout.contains("Program"),
+        "run output should contain AST node"
+    );
+}
+
+#[test]
+fn bench_not_implemented() {
+    let output = Command::new("cargo")
+        .args(["run", "--", "bench"])
+        .output()
+        .expect("failed to run oxide bench");
+
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    assert!(
+        stderr.contains("not yet implemented"),
+        "bench should print not-implemented message"
+    );
+}
diff --git a/crates/oxide_cli/tests/fixtures/hello.js b/crates/oxide_cli/tests/fixtures/hello.js
new file mode 100644
index 00000000..e0ef5840
--- /dev/null
+++ b/crates/oxide_cli/tests/fixtures/hello.js
@@ -0,0 +1 @@
+1 + 2