updated api

docs/android-questionnaire-api.md

@@ -254,7 +254,8 @@ Fields:
 - `clients[].completedQuestionnaires`: array of questionnaires already completed by this client. Empty array if none.
 - `clients[].completedQuestionnaires[].questionnaireID`: the questionnaire ID, matching the IDs from the questionnaire list endpoint.
 - `clients[].completedQuestionnaires[].sumPoints`: total points from the last upload for this questionnaire.
-- `clients[].completedQuestionnaires[].completedAt`: Unix timestamp (seconds) of when the questionnaire was completed, or `null` if not recorded.
+- `clients[].completedQuestionnaires[].completedAt`: when the questionnaire was completed on the device (milliseconds), or `null`.
+- `clients[].completedQuestionnaires[].uploadedAt`: when the latest version was received on the server (milliseconds), or `null`.
 
 Common failures:
 
@@ -368,14 +369,16 @@ Answer fields:
 - `numericValue`: for numeric/range answers.
 - `answeredAt`: timestamp for this answer.
 
-Current upload behavior:
+Upload behavior:
 
 - Unknown or empty `questionID` values are skipped.
 - Unknown `answerOptionKey` values are stored as no selected option for that question.
-- Re-uploading the same `clientCode` and `questionID` overwrites the previous answer.
-- Re-uploading the same `clientCode` and `questionnaireID` overwrites the completed questionnaire status and point sum.
+- Each successful POST **appends** an immutable `questionnaire_submission` record (version increments per client + questionnaire).
+- The latest answers are also written to the `client_answer` cache used by web results/CSV (always shows newest only).
+- `uploadedAt` is set by the server at POST time (milliseconds); do not send it from the client.
+- `completedAt` in the request is the device completion time; it is stored separately from `uploadedAt`.
 - `sumPoints` is calculated from recognized `answerOptionKey` values.
-- The current database stores one selected answer option per question. If the Android UI allows multiple selections for a layout, coordinate a server change before uploading multiple option keys for one question.
+- Coaches may re-open, edit, and POST again; each upload creates a new submission version.
 
 Success:
 
@@ -384,11 +387,20 @@ Success:
   "ok": true,
   "data": {
     "submitted": true,
-    "sumPoints": 0
+    "sumPoints": 0,
+    "submissionID": "sub_…",
+    "uploadedAt": 1714471800123,
+    "submissionVersion": 2
   }
 }
 ```
 
+## Fetch Latest Answers (re-edit)
+
+`GET /api/app_questionnaires?clientCode={code}&questionnaireID={id}&answers=1`
+
+Returns the **latest** cached answers for a client/questionnaire in the same shape as POST `answers[]`. Use before reopening a completed questionnaire on the tablet.
+
 Common failures:
 
 - `400 INVALID_BODY`: request body is not valid JSON.