feat(remote): implement outbound ID table for local actor identity on the wire

- Proxy passes sender's handle pointer as from_id instead of 0
- Endpoint assigns stable wire IDs to local actors on first send, keyed by handle pointer
- Reverse table (wire_id → pid) enables inbound send routing to local actors by ID
- Full bidirectional send-by-ID is now functional end-to-end

src/remote/endpoint.zig

@@ -31,6 +31,11 @@ const Endpoint = struct {
     accumulator: framing.Accumulator,
     /// Inbound proxy table: remote actor ID → local proxy pid.
     proxies: std.AutoHashMap(u64, tp.pid),
+    /// Outbound table: local actor handle pointer → assigned wire ID.
+    outbound: std.AutoHashMap(usize, u64),
+    /// Local actor table: wire ID → local actor pid (reverse of outbound).
+    local_actors: std.AutoHashMap(u64, tp.pid),
+    next_id: u64,
     receiver: tp.Receiver(*@This()),
 
     fn start(args: Args) tp.result {
@@ -46,6 +51,9 @@ const Endpoint = struct {
             .proc = proc,
             .accumulator = .{},
             .proxies = std.AutoHashMap(u64, tp.pid).init(args.allocator),
+            .outbound = std.AutoHashMap(usize, u64).init(args.allocator),
+            .local_actors = std.AutoHashMap(u64, tp.pid).init(args.allocator),
+            .next_id = 1,
             .receiver = .init(receive_fn, deinit, self),
         };
         errdefer self.deinit();
@@ -54,12 +62,16 @@ const Endpoint = struct {
 
     fn deinit(self: *@This()) void {
         // Exit all live proxies (best-effort; endpoint may already be shutting down).
-        var it = self.proxies.valueIterator();
-        while (it.next()) |p| {
+        var proxy_it = self.proxies.valueIterator();
+        while (proxy_it.next()) |p| {
             p.send(.{ "exit", "transport_closed" }) catch {};
             p.deinit();
         }
         self.proxies.deinit();
+        var actor_it = self.local_actors.valueIterator();
+        while (actor_it.next()) |p| p.deinit();
+        self.local_actors.deinit();
+        self.outbound.deinit();
         self.proc.deinit();
         self.allocator.destroy(self);
     }
@@ -81,7 +93,9 @@ const Endpoint = struct {
         } else if (try m.match(.{ proc_tag, "stderr", tp.any })) {
         } else if (try m.match(.{ "send", tp.extract(&from_id), tp.extract(&to_id), cbor.extract_cbor(&payload) })) {
             // Outbound send by remote ID — from a local proxy.
-            try self.send_wire_by_id(from_id, to_id, payload);
+            // from_id carries the sender's handle pointer; resolve to wire ID.
+            const wire_from_id = try self.get_or_assign_outbound_id(from_id);
+            try self.send_wire_by_id(wire_from_id, to_id, payload);
         } else if (try m.match(.{ "send", tp.extract(&from_id), tp.extract(&to_name), cbor.extract_cbor(&payload) })) {
             // Outbound send_named — from a local actor addressing a well-known remote actor by name.
             try self.send_wire_named(from_id, to_name, payload);
@@ -95,6 +109,20 @@ const Endpoint = struct {
         }
     }
 
+    /// Look up or assign a stable wire ID for a local actor identified by its
+    /// handle pointer. Also records the pid so inbound sends can be routed back.
+    fn get_or_assign_outbound_id(self: *@This(), handle_int: u64) !u64 {
+        const key: usize = @intCast(handle_int);
+        if (self.outbound.get(key)) |id| return id;
+        const id = self.next_id;
+        self.next_id += 1;
+        // Reconstruct a pid_ref from the handle pointer and clone it for storage.
+        const pid_ref: tp.pid_ref = .{ .h = @ptrFromInt(key) };
+        try self.local_actors.put(id, pid_ref.clone());
+        try self.outbound.put(key, id);
+        return id;
+    }
+
     /// Get the local proxy for remote_id, creating one if it doesn't exist yet.
     fn get_or_create_proxy(self: *@This(), remote_id: u64) !tp.pid_ref {
         if (self.proxies.getPtr(remote_id)) |p| return p.ref();
@@ -113,11 +141,11 @@ const Endpoint = struct {
             .send => |s| {
                 // Ensure a local proxy exists for the sender.
                 _ = try self.get_or_create_proxy(s.from_id);
-                // Deliver payload to the local actor identified by to_id.
-                // Requires the outbound ID table (not yet implemented); error for now.
-                _ = s.to_id;
-                _ = s.payload;
-                return tp.exit_error(error.OutboundTableNotImplemented, null);
+                // Route to the local actor that owns this wire ID.
+                if (self.local_actors.get(s.to_id)) |actor|
+                    try actor.send_raw(tp.message{ .buf = s.payload })
+                else
+                    return tp.exit_error(error.UnknownLocalActor, null);
             },
             .send_named => |s| {
                 // Ensure a local proxy exists for the sender so it can receive replies.

src/remote/proxy.zig

@@ -54,7 +54,7 @@ const Proxy = struct {
         return self.receive(from, m) catch |e| return tp.exit_error(e, @errorReturnTrace());
     }
 
-    fn receive(self: *@This(), _: tp.pid_ref, m: tp.message) !void {
+    fn receive(self: *@This(), from: tp.pid_ref, m: tp.message) !void {
         var reason: []const u8 = "";
 
         if (try m.match(.{ "exit", tp.extract(&reason) })) {
@@ -66,8 +66,9 @@ const Proxy = struct {
         }
 
         // Forward all other messages to the endpoint for wire transmission.
-        // from_id = 0 until outbound ID tracking is implemented.
-        try self.endpoint.send(.{ "send", @as(u64, 0), self.remote_id, protocol.RawCbor{ .bytes = m.buf } });
+        // Pass the sender's handle pointer as an opaque u64 so the endpoint
+        // can assign (or look up) a stable outbound wire ID for this actor.
+        try self.endpoint.send(.{ "send", @as(u64, @intFromPtr(from.h)), self.remote_id, protocol.RawCbor{ .bytes = m.buf } });
     }
 };