fix(session): tolerate negative token counts in stored parts (#26620)

packages/opencode/src/session/message-v2.ts

@@ -270,13 +270,13 @@ export const StepFinishPart = Schema.Struct({
   snapshot: Schema.optional(Schema.String),
   cost: Schema.Finite,
   tokens: Schema.Struct({
-    total: Schema.optional(NonNegativeInt),
-    input: NonNegativeInt,
-    output: NonNegativeInt,
-    reasoning: NonNegativeInt,
+    total: Schema.optional(Schema.Finite),
+    input: Schema.Finite,
+    output: Schema.Finite,
+    reasoning: Schema.Finite,
     cache: Schema.Struct({
-      read: NonNegativeInt,
-      write: NonNegativeInt,
+      read: Schema.Finite,
+      write: Schema.Finite,
     }),
   }),
 })
@@ -554,13 +554,13 @@ export const Assistant = Schema.Struct({
   summary: Schema.optional(Schema.Boolean),
   cost: Schema.Finite,
   tokens: Schema.Struct({
-    total: Schema.optional(NonNegativeInt),
-    input: NonNegativeInt,
-    output: NonNegativeInt,
-    reasoning: NonNegativeInt,
+    total: Schema.optional(Schema.Finite),
+    input: Schema.Finite,
+    output: Schema.Finite,
+    reasoning: Schema.Finite,
     cache: Schema.Struct({
-      read: NonNegativeInt,
-      write: NonNegativeInt,
+      read: Schema.Finite,
+      write: Schema.Finite,
     }),
   }),
   structured: Schema.optional(Schema.Any),

packages/opencode/src/session/message.ts

@@ -172,12 +172,12 @@ export const Info = Schema.Struct({
         cost: Schema.Finite,
         summary: Schema.optional(Schema.Boolean),
         tokens: Schema.Struct({
-          input: NonNegativeInt,
-          output: NonNegativeInt,
-          reasoning: NonNegativeInt,
+          input: Schema.Finite,
+          output: Schema.Finite,
+          reasoning: Schema.Finite,
           cache: Schema.Struct({
-            read: NonNegativeInt,
-            write: NonNegativeInt,
+            read: Schema.Finite,
+            write: Schema.Finite,
           }),
         }),
       }),

packages/opencode/src/session/session.ts

@@ -353,7 +353,7 @@ export function plan(input: { slug: string; time: { created: number } }, instanc
 export const getUsage = (input: { model: Provider.Model; usage: LanguageModelUsage; metadata?: ProviderMetadata }) => {
   const safe = (value: number) => {
     if (!Number.isFinite(value)) return 0
-    return value
+    return Math.max(0, value)
   }
   const inputTokens = safe(input.usage.inputTokens ?? 0)
   const outputTokens = safe(input.usage.outputTokens ?? 0)