[codex] split protocol crate modules

crates/protocol/src/error.rs

@@ -0,0 +1,11 @@
+use thiserror::Error;
+use tokio_util::codec::LinesCodecError;
+
+#[derive(Debug, Error)]
+pub enum ProtocolError {
+    #[error("daemon protocol JSON error: {0}")]
+    Json(#[from] serde_json::Error),
+
+    #[error("daemon protocol frame error: {0}")]
+    Frame(#[from] LinesCodecError),
+}

crates/protocol/src/event.rs

@@ -0,0 +1,27 @@
+use serde::Serialize;
+
+#[derive(Debug, Serialize)]
+#[serde(tag = "type", rename_all = "snake_case")]
+pub enum DaemonEvent<'message> {
+    JobStarted {
+        job_id: &'message str,
+        kind: &'message str,
+        scope: &'message str,
+    },
+    Progress {
+        job_id: &'message str,
+        message: &'message str,
+    },
+    Log {
+        job_id: &'message str,
+        message: &'message str,
+    },
+    JobCompleted {
+        job_id: &'message str,
+        summary: &'message str,
+    },
+    JobFailed {
+        job_id: &'message str,
+        error: &'message str,
+    },
+}