diff --git a/packages/server/src/server/agent/providers/opencode-agent.test.ts b/packages/server/src/server/agent/providers/opencode-agent.test.ts
index fd36a75cb9..1ba8b282a9 100644
--- a/packages/server/src/server/agent/providers/opencode-agent.test.ts
+++ b/packages/server/src/server/agent/providers/opencode-agent.test.ts
@@ -1944,6 +1944,75 @@ describe("OpenCode adapter startTurn error handling", () => {
     ]);
   });
 
+  test("streamHistory hides user text that OpenCode marks synthetic", async () => {
+    const fakeClient = {
+      session: {
+        get: vi.fn().mockResolvedValue({
+          data: { revert: undefined },
+          error: undefined,
+        }),
+        messages: vi.fn().mockResolvedValue({
+          data: [
+            {
+              info: { id: "msg_continue", sessionID: "ses_unit_test", role: "user" },
+              parts: [
+                {
+                  id: "prt_continue",
+                  sessionID: "ses_unit_test",
+                  messageID: "msg_continue",
+                  type: "text",
+                  text: "Summarize the task tool output above and continue with your task.",
+                  synthetic: true,
+                },
+              ],
+            },
+            {
+              info: { id: "msg_user", sessionID: "ses_unit_test", role: "user" },
+              parts: [
+                {
+                  id: "prt_user",
+                  sessionID: "ses_unit_test",
+                  messageID: "msg_user",
+                  type: "text",
+                  text: "Read the notes",
+                },
+                {
+                  id: "prt_resource",
+                  sessionID: "ses_unit_test",
+                  messageID: "msg_user",
+                  type: "text",
+                  text: "Reading MCP resource: notes.md",
+                  synthetic: true,
+                },
+              ],
+            },
+          ],
+          error: undefined,
+        }),
+      },
+    } as never;
+
+    const session = new __openCodeInternals.OpenCodeAgentSession(
+      { provider: "opencode", cwd: "/tmp/test" },
+      fakeClient,
+      "ses_unit_test",
+      createTestLogger(),
+    );
+
+    const history: AgentStreamEvent[] = [];
+    for await (const event of session.streamHistory()) {
+      history.push(event);
+    }
+
+    expect(history).toEqual([
+      {
+        type: "timeline",
+        provider: "opencode",
+        item: { type: "user_message", text: "Read the notes", messageId: "msg_user" },
+      },
+    ]);
+  });
+
   test("streamHistory omits replay timestamps when OpenCode omits times", async () => {
     const fakeClient = {
       session: {
diff --git a/packages/server/src/server/agent/providers/opencode-agent.ts b/packages/server/src/server/agent/providers/opencode-agent.ts
index 362f2a7442..2276e85786 100644
--- a/packages/server/src/server/agent/providers/opencode-agent.ts
+++ b/packages/server/src/server/agent/providers/opencode-agent.ts
@@ -1318,7 +1318,10 @@ function buildOpenCodeReplayTimelineEvents(
   }
   if (info.role === "user") {
     const text = parts
-      .filter((part): part is Extract<OpenCodePart, { type: "text" }> => part.type === "text")
+      .filter(
+        (part): part is Extract<OpenCodePart, { type: "text" }> =>
+          part.type === "text" && isUserAuthoredOpenCodeText(part),
+      )
       .map((part) => part.text)
       .join("");
 
@@ -2854,6 +2857,11 @@ function shouldSuppressOpenCodeAssistantPart(
   );
 }
 
+// OpenCode marks text it adds to a user message itself with `synthetic` and hides it from its own UI.
+function isUserAuthoredOpenCodeText(part: { synthetic?: boolean }): boolean {
+  return part.synthetic !== true;
+}
+
 function appendOpenCodeTextPart(
   part: Extract<
     Extract<OpenCodeEvent, { type: "message.part.updated" }>["properties"]["part"],
@@ -2864,7 +2872,11 @@ function appendOpenCodeTextPart(
   events: AgentStreamEvent[],
 ): void {
   if (messageRole === "user") {
-    if (!part.text || state.emittedUserMessageIds?.has(part.messageID)) {
+    if (
+      !part.text ||
+      !isUserAuthoredOpenCodeText(part) ||
+      state.emittedUserMessageIds?.has(part.messageID)
+    ) {
       return;
     }
     state.emittedUserMessageIds?.add(part.messageID);
diff --git a/packages/server/src/server/agent/providers/opencode/event-translator.test.ts b/packages/server/src/server/agent/providers/opencode/event-translator.test.ts
index 50a3a9edfe..69977f1ab9 100644
--- a/packages/server/src/server/agent/providers/opencode/event-translator.test.ts
+++ b/packages/server/src/server/agent/providers/opencode/event-translator.test.ts
@@ -1276,6 +1276,44 @@ describe("translateOpenCodeEvent", () => {
     expect(result).toEqual([]);
   });
 
+  it("shows OpenCode user text parts unless OpenCode marks them synthetic", () => {
+    const state = createState();
+    const userTextPart = (messageId: string, text: string, synthetic: boolean) => {
+      translateOpenCodeEvent(
+        {
+          type: "message.updated",
+          properties: { info: { id: messageId, sessionID: "session-1", role: "user" } },
+        },
+        state,
+      );
+      return translateOpenCodeEvent(
+        {
+          type: "message.part.updated",
+          properties: {
+            part: {
+              id: `part-${messageId}`,
+              sessionID: "session-1",
+              messageID: messageId,
+              type: "text",
+              text,
+              synthetic,
+            },
+          },
+        },
+        state,
+      );
+    };
+
+    expect(userTextPart("msg-continue", "Continue if you have next steps", true)).toEqual([]);
+    expect(userTextPart("msg-user", "Plugin prompt", false)).toEqual([
+      {
+        type: "timeline",
+        provider: "opencode",
+        item: { type: "user_message", text: "Plugin prompt", messageId: "msg-user" },
+      },
+    ]);
+  });
+
   it("ignores message.part.delta for user messages", () => {
     const state = createState();