fix(core): resolve prompt attachment mime types

packages/core/src/session.ts

@@ -10,6 +10,7 @@ import { ModelV2 } from "./model"
 import { Location } from "./location"
 import { SessionMessage } from "./session/message"
 import { Prompt } from "./session/prompt"
+import { PromptInput } from "@opencode-ai/schema/prompt-input"
 import { EventV2 } from "./event"
 import { Database } from "./database/database"
 import { SessionProjector } from "./session/projector"
@@ -32,6 +33,7 @@ import { SessionInput } from "./session/input"
 import { Snapshot } from "./snapshot"
 import { SessionRevert } from "./session/revert"
 import { Revert } from "@opencode-ai/schema/revert"
+import { FSUtil } from "./fs-util"
 
 export const RevertState = Revert.State
 export type RevertState = Revert.State
@@ -137,7 +139,7 @@ export interface Interface {
   readonly prompt: (input: {
     id?: SessionMessage.ID
     sessionID: SessionSchema.ID
-    prompt: Prompt
+    prompt: PromptInput.Prompt
     delivery?: SessionInput.Delivery
     resume?: boolean
   }) => Effect.Effect<SessionInput.Admitted, NotFoundError | PromptConflictError>
@@ -349,13 +351,14 @@ export const layer = Layer.unwrap(
               Effect.uninterruptible(
                 Effect.gen(function* () {
                   yield* result.get(input.sessionID)
+                  const prompt = resolvePrompt(input.prompt)
                   const messageID = input.id ?? SessionMessage.ID.create()
                   const delivery = input.delivery ?? "steer"
-                  const expected = { sessionID: input.sessionID, messageID, prompt: input.prompt, delivery }
+                  const expected = { sessionID: input.sessionID, messageID, prompt, delivery }
                   const admitted = yield* SessionInput.admit(db, events, {
                     id: messageID,
                     sessionID: input.sessionID,
-                    prompt: input.prompt,
+                    prompt,
                     delivery,
                   }).pipe(
                     Effect.catchDefect((defect) =>
@@ -452,3 +455,17 @@ export const defaultLayer = layer.pipe(
   Layer.provide(ProjectV2.defaultLayer),
   Layer.orDie,
 )
+
+const resolvePrompt = (input: PromptInput.Prompt) =>
+  Prompt.make({
+    text: input.text,
+    agents: input.agents,
+    files: input.files?.map((file) => {
+      const dataMime = file.uri.match(/^data:([^;,]+)[;,]/i)?.[1]
+      const target = URL.canParse(file.uri) ? new URL(file.uri).pathname : (file.name ?? file.uri)
+      return {
+        ...file,
+        mime: dataMime ?? (target.endsWith("/") ? "application/x-directory" : FSUtil.mimeType(target)),
+      }
+    }),
+  })

packages/core/test/session-prompt.test.ts

@@ -173,6 +173,27 @@ describe("SessionV2.prompt", () => {
     }),
   )
 
+  it.effect("resolves attachment MIME before admission", () =>
+    Effect.gen(function* () {
+      yield* setup
+      const session = yield* SessionV2.Service
+
+      const message = yield* session.prompt({
+        sessionID,
+        prompt: {
+          text: "Inspect this image",
+          files: [{ uri: "data:image/png;base64,aGVsbG8=", name: "image.png" }],
+        },
+        resume: false,
+      })
+
+      expect(message.prompt.files).toEqual([
+        { uri: "data:image/png;base64,aGVsbG8=", name: "image.png", mime: "image/png" },
+      ])
+      expect((yield* admitted(message.id))?.prompt.files).toEqual(message.prompt.files)
+    }),
+  )
+
   it.effect("streams durable Session events after an aggregate sequence", () =>
     Effect.gen(function* () {
       yield* setup