feat(token-meter): project durable token usage

packages/llm/token-meter/src/projection.ts

@@ -0,0 +1,25 @@
+/**
+ * Pure client-safe token-usage projection vocabulary.
+ *
+ * @module @deepseek-ai/dsh-token-meter/projection
+ */
+
+/**
+ * Durable cumulative provider usage for a complete session log.
+ *
+ * The four buckets are disjoint. In particular, reasoning tokens are already
+ * included in `outputTokens` and are not accumulated again.
+ */
+export interface TokenUsageProjection {
+  uncachedInputTokens: number
+  outputTokens: number
+  cacheReadTokens: number
+  cacheWriteTokens: number
+}
+
+declare module '@deepseek-ai/dsh-session-projection/types' {
+  interface SessionProjectionMap {
+    /** Provider-reported usage accumulated across the complete durable log. */
+    tokenUsage: TokenUsageProjection
+  }
+}