fix(token-meter): close projected usage review gaps

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

@@ -20,8 +20,8 @@ export interface TokenUsageProjection {
 /**
  * Approximate context occupancy for a status display.
  *
- * The two fields are deliberately NOT one atomic request observation:
- * `pressureTokens` is the newest provider-reported prompt size in the log,
+ * The two fields, when present, are deliberately NOT one atomic request
+ * observation: `pressureTokens` is the newest provider-reported prompt size,
  * `contextWindow` the newest recorded route capacity. Switching models can
  * therefore pair a fresh capacity with the previous route's pressure until the
  * next request reports usage. This is an intentional trade — the value is a
@@ -33,9 +33,9 @@ export interface ContextPressureProjection {
   /**
    * Provider-reported prompt size of the most recent request: uncached input
    * plus cache reads and writes. Response output is excluded, so this does not
-   * grow as the current turn streams.
+   * grow as the current turn streams. Absent until a provider reports usage.
    */
-  pressureTokens: number
+  pressureTokens?: number
   /** Newest recorded route capacity; absent when no adapter advertised one. */
   contextWindow?: number
 }

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

@@ -56,10 +56,10 @@ const projectionSchema = z.object({
   cacheWriteTokens: z.number().int().nonnegative(),
 }).strict()
 
-// Cast for the optional capacity: under exactOptionalPropertyTypes zod infers
-// `number | undefined` where the interface declares an absent-or-number field.
+// Cast for the optional values: under exactOptionalPropertyTypes zod infers
+// `number | undefined` where the interface declares absent-or-number fields.
 const pressureSchema = z.object({
-  pressureTokens: z.number().int().nonnegative(),
+  pressureTokens: z.number().int().nonnegative().optional(),
   contextWindow: z.number().int().positive().optional(),
 }).strict() as unknown as z.ZodType<ContextPressureProjection>
 
@@ -128,12 +128,14 @@ export const contextPressureProjectionDefinition:
 ProjectionDefinition<'contextPressure', ContextPressureProjection> = {
   key: 'contextPressure',
   schema: pressureSchema,
-  init: () => ({ pressureTokens: 0 }),
+  init: () => ({}),
   apply: (state, event) => {
     if (event.type === 'request/context') {
-      return event.data.contextWindow === state.contextWindow
-        ? state
-        : { ...state, contextWindow: event.data.contextWindow }
+      const contextWindow = event.data.contextWindow
+      if (contextWindow === state.contextWindow) return state
+      if (contextWindow !== undefined) return { ...state, contextWindow }
+      const { contextWindow: _removed, ...withoutContextWindow } = state
+      return withoutContextWindow
     }
     const usage = event.type === 'assistant/chunk' && event.data.chunk.type === 'usage'
       ? event.data.chunk.usage
@@ -147,5 +149,5 @@ ProjectionDefinition<'contextPressure', ContextPressureProjection> = {
       : { ...state, pressureTokens }
   },
   view: state => state,
-  stateVersion: 1,
+  stateVersion: 2,
 }