From 9a7cc8faed186668e08a2b15df6c29482e9e570f Mon Sep 17 00:00:00 2001
From: CJ van den Berg <cj@vdbonline.com>
Date: Tue, 10 Mar 2026 15:46:02 +0100
Subject: [PATCH] refactor: implement transport_error

---
 src/remote/endpoint.zig        |  3 ++-
 test/remote_child_endpoint.zig | 19 +++++++++++++++++--
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/src/remote/endpoint.zig b/src/remote/endpoint.zig
index 4bcb450..72d70b9 100644
--- a/src/remote/endpoint.zig
+++ b/src/remote/endpoint.zig
@@ -165,7 +165,8 @@ const Endpoint = struct {
                 if (self.proxies.get(e.id)) |p|
                     p.send(.{ "exit", e.reason }) catch {};
             },
-            .link, .transport_error => return tp.exit_error(error.UnexpectedMessage, null),
+            .transport_error => |te| return tp.exit(te.reason),
+            .link => return tp.exit_error(error.UnexpectedMessage, null),
         }
     }
 
diff --git a/test/remote_child_endpoint.zig b/test/remote_child_endpoint.zig
index fdb3e8a..5fbfe22 100644
--- a/test/remote_child_endpoint.zig
+++ b/test/remote_child_endpoint.zig
@@ -218,6 +218,7 @@ const StdioEndpoint = struct {
             try self.dispatch_stdin();
             try self.fd_stdin.wait_read();
         } else if (try m.match(.{ "fd", "stdin", "read_error", tp.any, tp.any })) {
+            self.send_transport_error("stdin_closed");
             return tp.exit("stdin_closed");
         } else if (try m.match(.{ "send", tp.extract(&from_id), tp.extract(&to_id_wire), cbor.extract_cbor(&payload) })) {
             try self.send_wire_by_id(from_id, to_id_wire, payload);
@@ -233,7 +234,10 @@ const StdioEndpoint = struct {
             error.WouldBlock => return,
             else => return tp.exit_error(e, @errorReturnTrace()),
         };
-        if (n == 0) return tp.exit("stdin_closed");
+        if (n == 0) {
+            self.send_transport_error("stdin_closed");
+            return tp.exit("stdin_closed");
+        }
         if (self.accumulator.feed(self.read_buf[0..n])) |frame| {
             try self.dispatch_frame(frame);
         }
@@ -254,7 +258,8 @@ const StdioEndpoint = struct {
                 else
                     return tp.exit_error(error.UnknownWireId, null);
             },
-            .link, .exit, .transport_error => return tp.exit_error(error.UnexpectedMessage, null),
+            .transport_error => |te| return tp.exit(te.reason),
+            .link, .exit => return tp.exit_error(error.UnexpectedMessage, null),
         }
     }
 
@@ -279,6 +284,16 @@ const StdioEndpoint = struct {
         try framing.write_frame(&frame_stream, msg_stream.buffered());
         try std.fs.File.stdout().writeAll(frame_stream.buffered());
     }
+
+    fn send_transport_error(_: *@This(), reason: []const u8) void {
+        var msg_buf: [framing.max_frame_size]u8 = undefined;
+        var msg_stream: std.Io.Writer = .fixed(&msg_buf);
+        protocol.encode_transport_error(&msg_stream, reason) catch return;
+        var frame_buf: [framing.max_frame_size + 4]u8 = undefined;
+        var frame_stream: std.Io.Writer = .fixed(&frame_buf);
+        framing.write_frame(&frame_stream, msg_stream.buffered()) catch return;
+        std.fs.File.stdout().writeAll(frame_stream.buffered()) catch {};
+    }
 };
 
 // ---------------------------------------------------------------------------