fix(send-poll): preserve whatsmeow's 0=unlimited semantics

Reverts the over-restrictive validation introduced in 9b8e7f0:
whatsmeow's BuildPollCreation treats selectableOptionCount=0 as
"multi-select with no limit" (msgsecret.go:300-308) and silently
coerces out-of-range values to 0. Forcing a minimum of 1 and
defaulting omitted requests to 1 silently removed access to the
unlimited-select mode and rewrote caller intent.

- Allow 0 (unlimited) again in both Python and Go validation; reject
  only negative or > len(options).
- Drop the *int pointer indirection on SendPollRequest — int's
  zero-value already maps cleanly to whatsmeow's "unlimited" sentinel.
- Document the three-way semantics on the request type and update
  error messages.
- Replace the zero-rejection test with one asserting 0 is accepted
  and forwarded as-is, plus a negative-value rejection test.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: Ortes

whatsapp-bridge/main.go

@@ -819,14 +819,17 @@ func sendWhatsAppMessage(client *whatsmeow.Client, recipient string, message str
 	return true, fmt.Sprintf("Message sent to %s", recipient)
 }
 
-// SendPollRequest represents the request body for the send poll API
+// SendPollRequest represents the request body for the send poll API.
+// SelectableOptionCount follows whatsmeow semantics:
+//
+//	0 = multi-select with no limit (also the zero-value default when omitted)
+//	1 = single-select
+//	N = multi-select up to N (1 < N <= len(Options))
 type SendPollRequest struct {
-	Recipient string   `json:"recipient"`
-	Name      string   `json:"name"`
-	Options   []string `json:"options"`
-	// Pointer so we can distinguish "omitted" (nil → default to 1)
-	// from "explicitly set to 0" (rejected by validation).
-	SelectableOptionCount *int `json:"selectable_option_count,omitempty"`
+	Recipient             string   `json:"recipient"`
+	Name                  string   `json:"name"`
+	Options               []string `json:"options"`
+	SelectableOptionCount int      `json:"selectable_option_count,omitempty"`
 }
 
 // resolveRecipientJID parses a phone number or JID string and resolves PN -> LID
@@ -1518,16 +1521,14 @@ func startRESTServer(client *whatsmeow.Client, messageStore *MessageStore, port
 				return
 			}
 		}
-		selectable := 1
-		if req.SelectableOptionCount != nil {
-			selectable = *req.SelectableOptionCount
-		}
-		if selectable < 1 || selectable > len(req.Options) {
-			http.Error(w, "selectable_option_count must be between 1 and len(options)", http.StatusBadRequest)
+		// whatsmeow coerces out-of-range values to 0, which silently changes the
+		// poll's selection mode. Reject them upfront so the caller knows.
+		if req.SelectableOptionCount < 0 || req.SelectableOptionCount > len(req.Options) {
+			http.Error(w, "selectable_option_count must be 0 (unlimited) or between 1 and len(options)", http.StatusBadRequest)
 			return
 		}
 
-		success, message := sendWhatsAppPoll(client, req.Recipient, req.Name, req.Options, selectable)
+		success, message := sendWhatsAppPoll(client, req.Recipient, req.Name, req.Options, req.SelectableOptionCount)
 
 		w.Header().Set("Content-Type", "application/json")
 		if !success {

whatsapp-mcp-server/tests/test_send_poll.py

@@ -36,11 +36,22 @@ def test_selectable_count_out_of_range(self):
         assert not ok
         assert "selectable_option_count" in msg
 
-    def test_selectable_count_zero_rejected(self):
-        ok, msg = send_poll("123@s.whatsapp.net", "Q?", ["a", "b"], selectable_option_count=0)
+    def test_selectable_count_negative_rejected(self):
+        ok, msg = send_poll("123@s.whatsapp.net", "Q?", ["a", "b"], selectable_option_count=-1)
         assert not ok
         assert "selectable_option_count" in msg
 
+    def test_selectable_count_zero_allowed_unlimited(self):
+        # whatsmeow treats 0 as "multi-select with no limit" — must remain valid.
+        with patch("whatsapp.requests.post") as mock_post:
+            mock_post.return_value.status_code = 200
+            mock_post.return_value.json.return_value = {"success": True, "message": "Poll sent to 123"}
+
+            ok, _ = send_poll("123@s.whatsapp.net", "Q?", ["a", "b"], selectable_option_count=0)
+
+            assert ok
+            assert mock_post.call_args.kwargs["json"]["selectable_option_count"] == 0
+
     def test_valid_request_calls_bridge(self):
         with patch("whatsapp.requests.post") as mock_post:
             mock_post.return_value.status_code = 200