diff --git a/src/sessions/user-turn-transcript.test.ts b/src/sessions/user-turn-transcript.test.ts
index dd2b4022356..42ce88b85a6 100644
--- a/src/sessions/user-turn-transcript.test.ts
+++ b/src/sessions/user-turn-transcript.test.ts
@@ -1,5 +1,8 @@
 import { describe, expect, it } from "vitest";
-import { buildPersistedUserTurnMediaFields } from "./user-turn-transcript.js";
+import {
+  buildPersistedUserTurnMediaFields,
+  buildPersistedUserTurnMessage,
+} from "./user-turn-transcript.js";
 
 describe("user turn transcript persistence", () => {
   describe("buildPersistedUserTurnMediaFields", () => {
@@ -66,4 +69,84 @@ describe("user turn transcript persistence", () => {
       });
     });
   });
+
+  describe("buildPersistedUserTurnMessage", () => {
+    it("builds a plain user transcript message for text-only turns", () => {
+      expect(
+        buildPersistedUserTurnMessage({
+          text: "hello",
+          timestamp: 123,
+          idempotencyKey: "turn-1",
+        }),
+      ).toEqual({
+        role: "user",
+        content: "hello",
+        timestamp: 123,
+        idempotencyKey: "turn-1",
+      });
+    });
+
+    it("adds structured media fields to the user transcript message", () => {
+      expect(
+        buildPersistedUserTurnMessage({
+          text: "What is in this image?",
+          media: [{ path: "/tmp/a.png", contentType: "image/png" }],
+          timestamp: 123,
+        }),
+      ).toEqual({
+        role: "user",
+        content: "What is in this image?",
+        timestamp: 123,
+        MediaPath: "/tmp/a.png",
+        MediaPaths: ["/tmp/a.png"],
+        MediaType: "image/png",
+        MediaTypes: ["image/png"],
+      });
+    });
+
+    it("does not infer media from marker-like user text", () => {
+      expect(
+        buildPersistedUserTurnMessage({
+          text: "[media attached: media://inbound/photo.png]\nWhat is this?",
+          timestamp: 123,
+        }),
+      ).toEqual({
+        role: "user",
+        content: "[media attached: media://inbound/photo.png]\nWhat is this?",
+        timestamp: 123,
+      });
+    });
+
+    it("uses an explicit media-only display text when provided", () => {
+      expect(
+        buildPersistedUserTurnMessage({
+          text: "",
+          mediaOnlyText: "[User sent media]",
+          media: [{ path: "/tmp/a.png", contentType: "image/png" }],
+        }),
+      ).toEqual({
+        role: "user",
+        content: "[User sent media]",
+        MediaPath: "/tmp/a.png",
+        MediaPaths: ["/tmp/a.png"],
+        MediaType: "image/png",
+        MediaTypes: ["image/png"],
+      });
+    });
+
+    it("keeps media-only transcript content empty by default", () => {
+      expect(
+        buildPersistedUserTurnMessage({
+          media: [{ path: "/tmp/a.png", contentType: "image/png" }],
+        }),
+      ).toEqual({
+        role: "user",
+        content: "",
+        MediaPath: "/tmp/a.png",
+        MediaPaths: ["/tmp/a.png"],
+        MediaType: "image/png",
+        MediaTypes: ["image/png"],
+      });
+    });
+  });
 });
diff --git a/src/sessions/user-turn-transcript.ts b/src/sessions/user-turn-transcript.ts
index f53fbfa2bda..1e4f1ec23e2 100644
--- a/src/sessions/user-turn-transcript.ts
+++ b/src/sessions/user-turn-transcript.ts
@@ -1,3 +1,5 @@
+import type { AgentMessage } from "@earendil-works/pi-agent-core";
+
 export type PersistedUserTurnMediaInput = {
   path?: string | null;
   url?: string | null;
@@ -12,11 +14,25 @@ export type PersistedUserTurnMediaFields = {
   MediaTypes?: string[];
 };
 
+export type PersistedUserTurnMessage = Extract<AgentMessage, { role: "user" }>;
+
+export type BuildPersistedUserTurnMessageParams = {
+  text?: string | null;
+  media?: readonly PersistedUserTurnMediaInput[] | null;
+  timestamp?: number;
+  idempotencyKey?: string;
+  mediaOnlyText?: string;
+};
+
 function normalizeOptionalText(value: string | null | undefined): string | undefined {
   const normalized = value?.trim();
   return normalized ? normalized : undefined;
 }
 
+function normalizeTranscriptText(value: string | null | undefined): string {
+  return value ?? "";
+}
+
 function mediaTypeForTranscript(media: PersistedUserTurnMediaInput): string {
   return (
     normalizeOptionalText(media.contentType) ??
@@ -60,3 +76,19 @@ export function buildPersistedUserTurnMediaFields(
     MediaTypes: types,
   };
 }
+
+export function buildPersistedUserTurnMessage(
+  params: BuildPersistedUserTurnMessageParams,
+): PersistedUserTurnMessage {
+  const mediaFields = buildPersistedUserTurnMediaFields(params.media);
+  const hasMedia = Boolean(mediaFields.MediaPath);
+  const text = normalizeTranscriptText(params.text);
+  const content = text || (hasMedia ? (params.mediaOnlyText ?? "") : "");
+  return {
+    role: "user",
+    content,
+    ...(params.timestamp !== undefined ? { timestamp: params.timestamp } : {}),
+    ...(params.idempotencyKey ? { idempotencyKey: params.idempotencyKey } : {}),
+    ...mediaFields,
+  } as PersistedUserTurnMessage;
+}