Add the paths, channel, loop and baseline config tables

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

crates/loopd/tests/config.rs

@@ -141,3 +141,86 @@ fn load_reports_which_file_failed() {
     let e: Box<dyn std::error::Error> = Box::new(Config::load(&missing).unwrap_err());
     assert!(e.to_string().contains("does-not-exist.toml"));
 }
+
+// ---- M2b: paths, channel, loop and baseline ----
+
+#[test]
+fn the_m2b_tables_have_defaults() {
+    let c = Config::load(&fixture("minimal.toml")).unwrap();
+    assert_eq!(
+        c.channel.socket,
+        PathBuf::new(),
+        "empty means: under the home"
+    );
+    assert_eq!(c.channel_socket(), c.paths.home.join("run/loop/loop.sock"));
+    assert_eq!(
+        (
+            c.r#loop.tool_iterations,
+            c.r#loop.repeat_detection,
+            c.r#loop.tool_result_cap
+        ),
+        (8, true, 16 * 1024)
+    );
+    // A relative system prompt is taken from the config file's directory.
+    assert_eq!(c.baseline.system, fixture("system.md"));
+    // The home comes from BOXMAKER_HOME when set, else /var/lib/boxmaker. Either way it is absolute.
+    assert!(c.paths.home.is_absolute(), "{:?}", c.paths.home);
+}
+
+#[test]
+fn the_m2b_tables_can_be_set() {
+    let c = Config::load(&fixture("m2b.toml")).unwrap();
+    assert_eq!(c.paths.home, PathBuf::from("/srv/boxmaker"));
+    assert_eq!(
+        c.channel.socket,
+        PathBuf::from("/run/boxmaker/loop/loop.sock")
+    );
+    assert_eq!(
+        c.channel_socket(),
+        PathBuf::from("/run/boxmaker/loop/loop.sock")
+    );
+    assert_eq!(
+        (
+            c.r#loop.tool_iterations,
+            c.r#loop.repeat_detection,
+            c.r#loop.tool_result_cap
+        ),
+        (3, false, 1024)
+    );
+    assert_eq!(
+        c.baseline.system,
+        fixture("prompts/agent.md"),
+        "relative to the config file"
+    );
+    let text = std::fs::read_to_string(fixture("m2b.toml")).unwrap();
+    let absolute = text.replace("prompts/agent.md", "/etc/boxmaker/system.md");
+    assert_eq!(
+        Config::parse(&absolute).unwrap().baseline.system,
+        PathBuf::from("/etc/boxmaker/system.md")
+    );
+}
+
+#[test]
+fn unknown_keys_are_errors_in_the_m2b_tables_too() {
+    let text = std::fs::read_to_string(fixture("m2b.toml")).unwrap();
+    assert!(Config::parse(&text).is_ok());
+    for table in ["paths", "channel", "loop", "baseline"] {
+        let header = format!("[{table}]\n");
+        let bad = text.replacen(&header, &format!("{header}zz_unknown = 1\n"), 1);
+        assert!(
+            Config::parse(&bad).is_err(),
+            "[{table}] accepted an unknown key"
+        );
+    }
+    let partial = text.replace("tool_iterations = 3\nrepeat_detection = false\n", "");
+    let c = Config::parse(&partial).unwrap();
+    assert_eq!(
+        (
+            c.r#loop.tool_iterations,
+            c.r#loop.repeat_detection,
+            c.r#loop.tool_result_cap
+        ),
+        (8, true, 1024),
+        "a partial table keeps the other defaults"
+    );
+}

crates/loopd/tests/fixtures/config/m2b.toml

@@ -0,0 +1,26 @@
+[infer]
+socket = "/tmp/infer.sock"
+model = "some-model"
+
+[slots]
+main = 0
+background = 1
+
+[expect]
+template_sha256 = "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f"
+n_ctx = 4096
+slots = 2
+
+[paths]
+home = "/srv/boxmaker"
+
+[channel]
+socket = "/run/boxmaker/loop/loop.sock"
+
+[loop]
+tool_iterations = 3
+repeat_detection = false
+tool_result_cap = 1024
+
+[baseline]
+system = "prompts/agent.md"