diff --git a/src/internal/xrpc/xrpc.zig b/src/internal/xrpc/xrpc.zig
index dd2e853..f50095c 100644
--- a/src/internal/xrpc/xrpc.zig
+++ b/src/internal/xrpc/xrpc.zig
@@ -38,6 +38,21 @@ pub const XrpcClient = struct {
         };
     }
 
+    /// Same as `init`, naming the calling application in the User-Agent rather
+    /// than zat. Anything issuing XRPC at scale should use this: the operator
+    /// on the other end wants to know which service is calling, not which
+    /// library it happens to be built on.
+    pub fn initWithUserAgent(
+        io: std.Io,
+        allocator: std.mem.Allocator,
+        host: []const u8,
+        user_agent: []const u8,
+    ) XrpcClient {
+        var client = init(io, allocator, host);
+        if (user_agent.len > 0) client.transport.user_agent = user_agent;
+        return client;
+    }
+
     pub fn deinit(self: *XrpcClient) void {
         self.transport.deinit();
     }
@@ -389,6 +404,18 @@ fn isRetryableTransportErrorForMethod(method: std.http.Method, err: anyerror) bo
 
 // === tests ===
 
+test "client user agent override reaches the transport" {
+    const testing = std.testing;
+
+    var named = XrpcClient.initWithUserAgent(std.Options.debug_io, testing.allocator, "https://bsky.social", "stream/1.2.3 (+https://example.invalid)");
+    defer named.deinit();
+    try testing.expectEqualStrings("stream/1.2.3 (+https://example.invalid)", named.transport.user_agent);
+
+    var empty = XrpcClient.initWithUserAgent(std.Options.debug_io, testing.allocator, "https://bsky.social", "");
+    defer empty.deinit();
+    try testing.expectEqualStrings(@import("transport.zig").default_user_agent, empty.transport.user_agent);
+}
+
 test "build url without params" {
     var client = XrpcClient.init(std.Options.debug_io, std.testing.allocator, "https://bsky.social");
     defer client.deinit();