From d05b9343f69a0841043963088e0003368e205bd9 Mon Sep 17 00:00:00 2001
From: Felix Morgner <felix.morgner@gmail.com>
Date: Tue, 22 Sep 2026 22:47:33 +0200
Subject: lib: restructure into vertical slices

---
 ttwhy/core/concepts.cppm | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 ttwhy/core/concepts.cppm

(limited to 'ttwhy/core/concepts.cppm')

diff --git a/ttwhy/core/concepts.cppm b/ttwhy/core/concepts.cppm
new file mode 100644
index 0000000..f7ac583
--- /dev/null
+++ b/ttwhy/core/concepts.cppm
@@ -0,0 +1,30 @@
+module;
+
+#include <asio.hpp>
+
+#include <concepts>
+#include <span>
+
+export module ttwhy.core:concepts;
+
+namespace ttwhy
+{
+
+  export template<typename Candidate>
+  concept scanner = requires(Candidate a, std::span<char const> buffer) {
+    { a.process(buffer) } -> std::same_as<void>;
+    { a.timeout() } -> std::same_as<void>;
+    { a.is_pending() } -> std::same_as<bool>;
+  };
+
+  export template<typename Candidate, typename Event>
+  concept router = requires(Candidate candidate, Event event) {
+    { candidate.process(event) } -> std::same_as<asio::awaitable<void>>;
+  };
+
+  export template<typename Sink, typename Event>
+  concept event_sink = requires(Sink sink, Event event) {
+    { sink(event) } -> std::same_as<void>;
+  };
+
+}  // namespace ttwhy
-- 
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