diff --git a/packages/opencode/src/cli/cmd/run.ts b/packages/opencode/src/cli/cmd/run.ts
index b80a2389ef24..6e4c4db8df35 100644
--- a/packages/opencode/src/cli/cmd/run.ts
+++ b/packages/opencode/src/cli/cmd/run.ts
@@ -789,12 +789,18 @@ export const RunCommand = effectCmd({
           }
 
           const model = pick(args.model)
+          const parts = [...files, { type: "text" as const, text: message }]
+          // Mirror the prompt to --format json consumers. The streamed
+          // message.part events only cover the assistant reply, so without this
+          // the user turn never appears in the stream (it lives only in
+          // `opencode export`).
+          emit("user", { parts })
           const result = await client.session.prompt({
             sessionID,
             agent,
             model,
             variant: args.variant,
-            parts: [...files, { type: "text", text: message }],
+            parts,
           })
           if (result.error) {
             if (!emit("error", { error: result.error })) UI.error(formatRunError(result.error))
diff --git a/packages/opencode/test/cli/run/run-process.test.ts b/packages/opencode/test/cli/run/run-process.test.ts
index 00d2e64b377e..8c526c4cdc61 100644
--- a/packages/opencode/test/cli/run/run-process.test.ts
+++ b/packages/opencode/test/cli/run/run-process.test.ts
@@ -81,4 +81,28 @@ describe("opencode run (non-interactive subprocess)", () => {
       }),
     60_000,
   )
+
+  // Regression for #29997: the user's prompt must surface in --format json as a
+  // `user` event. Previously the stream began at step_start and the prompt was
+  // only retrievable via `opencode export`, so anything rebuilding a transcript
+  // from the stream lost the user turn entirely.
+  cliIt.concurrent(
+    "--format json emits a user event carrying the prompt (regression for #29997)",
+    ({ llm, opencode }) =>
+      Effect.gen(function* () {
+        yield* llm.text("ok")
+        const result = yield* opencode.run("marco", { format: "json" })
+        opencode.expectExit(result, 0)
+
+        const events = opencode.parseJsonEvents(result.stdout)
+        const user = events.find((e) => e.type === "user")
+        expect(user).toBeDefined()
+        expect(JSON.stringify(user!.parts)).toContain("marco")
+
+        // The user turn must precede the assistant's reply in the stream.
+        const types = events.map((e) => e.type)
+        expect(types.indexOf("user")).toBeLessThan(types.indexOf("text"))
+      }),
+    60_000,
+  )
 })