wip: file part source in server/api (optional)

packages/opencode/src/session/index.ts

@@ -490,6 +490,12 @@ export namespace Session {
                     synthetic: true,
                     text: result.output,
                   },
+                  {
+                    ...part,
+                    id: part.id ?? Identifier.ascending("part"),
+                    messageID: userMsg.id,
+                    sessionID: input.sessionID,
+                  },
                 ]
               }
 
@@ -505,13 +511,14 @@ export namespace Session {
                   synthetic: true,
                 },
                 {
-                  id: Identifier.ascending("part"),
+                  id: part.id ?? Identifier.ascending("part"),
                   messageID: userMsg.id,
                   sessionID: input.sessionID,
                   type: "file",
                   url: `data:${part.mime};base64,` + Buffer.from(await file.bytes()).toString("base64"),
                   mime: part.mime,
                   filename: part.filename!,
+                  source: part.source,
                 },
               ]
           }

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

@@ -4,6 +4,7 @@ import { NamedError } from "../util/error"
 import { Message } from "./message"
 import { convertToModelMessages, type ModelMessage, type UIMessage } from "ai"
 import { Identifier } from "../id/id"
+import { LSP } from "../lsp"
 
 export namespace MessageV2 {
   export const OutputLengthError = NamedError.create("MessageOutputLengthError", z.object({}))
@@ -118,11 +119,45 @@ export namespace MessageV2 {
   })
   export type ToolPart = z.infer<typeof ToolPart>
 
+  const FilePartSourceBase = z.object({
+    text: z
+      .object({
+        value: z.string(),
+        start: z.number().int(),
+        end: z.number().int(),
+      })
+      .openapi({
+        ref: "FilePartSourceText",
+      }),
+  })
+
+  export const FileSource = FilePartSourceBase.extend({
+    type: z.literal("file"),
+    path: z.string(),
+  }).openapi({
+    ref: "FileSource",
+  })
+
+  export const SymbolSource = FilePartSourceBase.extend({
+    type: z.literal("symbol"),
+    path: z.string(),
+    range: LSP.Range,
+    name: z.string(),
+    kind: z.number().int(),
+  }).openapi({
+    ref: "SymbolSource",
+  })
+
+  export const FilePartSource = z.discriminatedUnion("type", [FileSource, SymbolSource]).openapi({
+    ref: "FilePartSource",
+  })
+
   export const FilePart = PartBase.extend({
     type: z.literal("file"),
     mime: z.string(),
     filename: z.string().optional(),
     url: z.string(),
+    source: FilePartSource.optional(),
   }).openapi({
     ref: "FilePart",
   })
@@ -394,7 +429,8 @@ export namespace MessageV2 {
                   text: part.text,
                 },
               ]
-            if (part.type === "file")
+            // text/plain files are converted into text parts, ignore them
+            if (part.type === "file" && part.mime !== "text/plain")
               return [
                 {
                   type: "file",