feat(session): expose LLM response headers on assistant messages

Author: jtbnz

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

@@ -578,6 +578,7 @@ export const Assistant = Schema.Struct({
   structured: Schema.optional(Schema.Any),
   variant: Schema.optional(Schema.String),
   finish: Schema.optional(Schema.String),
+  responseHeaders: Schema.optional(Schema.Record(Schema.String, Schema.String)),
 })
   .annotate({ identifier: "AssistantMessage" })
   .pipe(withStatics((s) => ({ zod: zod(s) })))

packages/opencode/src/session/processor.ts

@@ -471,6 +471,8 @@ export const layer: Layer.Layer<
             ctx.assistantMessage.finish = value.finishReason
             ctx.assistantMessage.cost += usage.cost
             ctx.assistantMessage.tokens = usage.tokens
+            if (value.response.headers && Object.keys(value.response.headers).length > 0)
+              ctx.assistantMessage.responseHeaders = value.response.headers
             yield* session.updatePart({
               id: PartID.ascending(),
               reason: value.finishReason,