refactor(core): resolve attachments durably at promotion

packages/schema/src/session-event.ts

@@ -105,10 +105,24 @@ export const Forked = Event.define({
 })
 export type Forked = typeof Forked.Type
 
+/**
+ * Model-visible content captured for one attachment URI at promotion time:
+ * a data URL for media, otherwise text. Recorded on the event so projection
+ * replay stays deterministic without filesystem access.
+ */
+export const AttachmentResolution = Schema.Struct({
+  uri: Schema.String,
+  resolved: Schema.String,
+}).annotate({ identifier: "session.next.event.attachment-resolution" })
+export interface AttachmentResolution extends Schema.Schema.Type<typeof AttachmentResolution> {}
+
 export const Prompted = Event.define({
   type: "session.next.prompted",
   ...options,
-  schema: PromptFields,
+  schema: {
+    ...PromptFields,
+    resolutions: Schema.Array(AttachmentResolution).pipe(optional),
+  },
 })
 export type Prompted = typeof Prompted.Type
 

packages/schema/src/session-message.ts

@@ -41,11 +41,22 @@ export const ModelSwitched = Schema.Struct({
   model: Model.Ref,
 }).annotate({ identifier: "Session.Message.ModelSwitched" })
 
+/**
+ * A prompt attachment plus the model-visible content captured for it at
+ * promotion time: a data URL for media, otherwise text. The original `uri`
+ * and `mime` are preserved for provenance; only `resolved` is server-produced.
+ */
+export interface UserFile extends Schema.Schema.Type<typeof UserFile> {}
+export const UserFile = Schema.Struct({
+  ...FileAttachment.fields,
+  resolved: Schema.String.pipe(optional),
+}).annotate({ identifier: "Session.Message.UserFile" })
+
 export interface User extends Schema.Schema.Type<typeof User> {}
 export const User = Schema.Struct({
   ...Base,
   text: Prompt.fields.text,
-  files: Prompt.fields.files,
+  files: Schema.Array(UserFile).pipe(optional),
   agents: Prompt.fields.agents,
   type: Schema.Literal("user"),
 }).annotate({ identifier: "Session.Message.User" })