fix: StartUserProgram based on protocol version

Author: afarago

src/ble-pybricks-service/actions.ts

@@ -55,17 +55,6 @@ export const sendStopUserProgramCommand = createAction((id: number) => ({
     id,
 }));
 
-/**
- * Action that requests a start user program to be sent.
- * @param id Unique identifier for this transaction.
- *
- * @since Pybricks Profile v1.2.0.
- */
-export const sendLegacyStartUserProgramCommand = createAction((id: number) => ({
-    type: 'blePybricksServiceCommand.action.sendLegacyStartUserProgramCommand',
-    id,
-}));
-
 /**
  * Action that requests a start user program to be sent.
  * @param id Unique identifier for this transaction.

src/ble-pybricks-service/sagas.ts

@@ -9,9 +9,11 @@ import {
     fork,
     put,
     race,
+    select,
     take,
     takeEvery,
 } from 'typed-redux-saga/macro';
+import { RootState } from '../reducers';
 import { ensureError, hex } from '../utils';
 import {
     didFailToSendCommand,
@@ -35,6 +37,7 @@ import {
 import {
     EventType,
     ProtocolError,
+    createLegacyStartUserProgramCommand,
     createStartReplCommand,
     createStartUserProgramCommand,
     createStopUserProgramCommand,
@@ -53,6 +56,7 @@ import {
  * the bytecodes to to the device.
  */
 function* encodeRequest(): Generator {
+    const { useLegacyStartUserProgram } = yield* select((s: RootState) => s.hub);
     // Using a loop to serialize sending data to avoid "busy" errors.
 
     const chan = yield* actionChannel(
@@ -68,9 +72,15 @@ function* encodeRequest(): Generator {
         if (sendStopUserProgramCommand.matches(action)) {
             yield* put(writeCommand(action.id, createStopUserProgramCommand()));
         } else if (sendStartUserProgramCommand.matches(action)) {
-            yield* put(
-                writeCommand(action.id, createStartUserProgramCommand(action.slot)),
-            );
+            if (useLegacyStartUserProgram) {
+                yield* put(
+                    writeCommand(action.id, createLegacyStartUserProgramCommand()),
+                );
+            } else {
+                yield* put(
+                    writeCommand(action.id, createStartUserProgramCommand(action.slot)),
+                );
+            }
         } else if (sendStartReplCommand.matches(action)) {
             yield* put(writeCommand(action.id, createStartReplCommand()));
         } else if (sendWriteUserProgramMetaCommand.matches(action)) {

src/hub/reducers.ts

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-// Copyright (c) 2020-2023 The Pybricks Authors
+// Copyright (c) 2020-2024 The Pybricks Authors
 
 import { Reducer, combineReducers } from 'redux';
 import * as semver from 'semver';
@@ -263,6 +263,18 @@ const useLegacyStdio: Reducer<boolean> = (state = false, action) => {
     return state;
 };
 
+/**
+ * When true, use Legacy StartUserProgram.
+ */
+const useLegacyStartUserProgram: Reducer<boolean> = (state = false, action) => {
+    if (bleDIServiceDidReceiveSoftwareRevision.matches(action)) {
+        // Behavior changed starting with Pybricks Profile v1.4.0.
+        return !semver.satisfies(action.version, '^1.4.0');
+    }
+
+    return state;
+};
+
 export default combineReducers({
     runtime,
     downloadProgress,
@@ -272,4 +284,5 @@ export default combineReducers({
     preferredFileFormat,
     useLegacyDownload,
     useLegacyStdio,
+    useLegacyStartUserProgram,
 });