Add the startup self-test and the loopd selftest command

Implemented-By: OpenCode session (model recorded in docs/implementer-log.md)

crates/loopd/src/main.rs

@@ -1,4 +1,47 @@
-fn main() {
-    eprintln!("loopd: not implemented until M2");
-    std::process::exit(2);
+//! `loopd`: the agent loop daemon. Its one command today is `selftest`, which runs the startup
+//! checks before `loopd` serves anyone.
+
+use std::path::Path;
+use std::process::ExitCode;
+
+use loopd::config::Config;
+use loopd::llama::Client;
+use loopd::selftest::run;
+
+fn main() -> ExitCode {
+    let args: Vec<String> = std::env::args().skip(1).collect();
+    let args: Vec<&str> = args.iter().map(String::as_str).collect();
+    match args.as_slice() {
+        ["selftest", "--config", path] => run_selftest(path),
+        _ => {
+            eprintln!("usage: loopd selftest --config <path>");
+            ExitCode::from(2)
+        }
+    }
+}
+
+fn run_selftest(path: &str) -> ExitCode {
+    let cfg = match Config::load(Path::new(path)) {
+        Ok(cfg) => cfg,
+        Err(e) => {
+            eprintln!("loopd: {e}");
+            return ExitCode::from(1);
+        }
+    };
+
+    let mut on_step = |step: &str| {
+        eprintln!("selftest: {step}");
+    };
+    let result = run(&Client::new(cfg), &mut on_step);
+
+    match result {
+        Ok(()) => {
+            eprintln!("selftest: ok");
+            ExitCode::SUCCESS
+        }
+        Err(e) => {
+            eprintln!("selftest: FAILED: {e}");
+            ExitCode::from(1)
+        }
+    }
 }