1 files changed, 34 insertions, 0 deletions
diff --git a/lib/dispatch/adapter/interface/pricing.rb b/lib/dispatch/adapter/interface/pricing.rb
new file mode 100644
index 0000000..a3ec9eb
--- /dev/null
+++ b/lib/dispatch/adapter/interface/pricing.rb
@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+module Dispatch
+  module Adapter
+    module Pricing
+      module_function
+
+      # Calculates UsageCost from a Usage and ModelInfo.
+      #
+      # NOTE: Reasoning tokens are NOT separately priced here.
+      # Anthropic bills them as output tokens; OpenAI o-series likewise.
+      # It is assumed that output_tokens includes reasoning_tokens if applicable.
+      def calculate(usage, model_info)
+        return nil unless model_info&.pricing
+
+        p = model_info.pricing
+        mtok = ->(tokens, rate) { (rate.to_f / 1_000_000.0) * tokens.to_i }
+
+        input  = mtok.call(usage.input_tokens,           p.input_per_mtok)
+        output = mtok.call(usage.output_tokens,          p.output_per_mtok)
+        cread  = mtok.call(usage.cache_read_tokens,      p.cache_read_per_mtok)
+        cwrite = mtok.call(usage.cache_creation_tokens,  p.cache_write_per_mtok)
+
+        UsageCost.new(
+          input: input,
+          output: output,
+          cache_read: cread,
+          cache_write: cwrite,
+          total: input + output + cread + cwrite
+        )
+      end
+    end
+  end
+end