Track altbody in change-detection so existing campaigns actually re-sync

Campaign/parseCampaign never fetched altbody, so campaignUnchanged()
compared everything except it -- a campaign synced before v0.1.3
(altbody always null) whose content otherwise hasn't changed would be
judged unchanged forever and never get updated with the new altbody,
even though every subsequent sync now intends to send one.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

internal/campaign/sync.go

@@ -217,6 +217,10 @@ func attachmentFilename(slug, relPath string, content []byte) string {
 func campaignUnchanged(existing *listmonk.Campaign, input listmonk.CampaignInput) bool {
 	return existing.Subject == input.Subject &&
 		existing.Body == input.Body &&
+		// altbody always mirrors body (see CampaignInput.payload) -- comparing
+		// it here is what catches a campaign synced before that started, whose
+		// stored altbody is still null even though its body hasn't changed.
+		existing.AltBody == input.Body &&
 		existing.FromEmail == input.FromEmail &&
 		existing.TemplateID == input.TemplateID &&
 		existing.Type == input.Type &&

internal/campaign/sync_test.go

@@ -31,6 +31,7 @@ type fakeCampaign struct {
 	Status     string
 	Subject    string
 	Body       string
+	AltBody    string
 	FromEmail  string
 	TemplateID int
 	Type       string
@@ -138,7 +139,7 @@ func (c fakeCampaign) toJSON() map[string]any {
 	}
 	return map[string]any{
 		"id": c.ID, "name": c.Name, "status": c.Status, "subject": c.Subject,
-		"body": c.Body, "from_email": c.FromEmail, "template_id": c.TemplateID,
+		"body": c.Body, "altbody": c.AltBody, "from_email": c.FromEmail, "template_id": c.TemplateID,
 		"type": c.Type, "tags": c.Tags, "lists": lists, "media": media,
 	}
 }
@@ -155,7 +156,7 @@ func (f *fakeListmonk) createCampaign(w http.ResponseWriter, r *http.Request) {
 	body := decodeBody(r)
 	c := fakeCampaign{
 		ID: f.id(), Name: str(body["name"]), Status: "draft",
-		Subject: str(body["subject"]), Body: str(body["body"]),
+		Subject: str(body["subject"]), Body: str(body["body"]), AltBody: str(body["altbody"]),
 		FromEmail: str(body["from_email"]), TemplateID: toInt(body["template_id"]),
 		Type: str(body["type"]), Tags: toStrings(body["tags"]),
 		ListIDs: toInts(body["lists"]), MediaIDs: toInts(body["media"]),
@@ -171,6 +172,7 @@ func (f *fakeListmonk) updateCampaign(w http.ResponseWriter, r *http.Request) {
 		if f.campaigns[i].ID == id {
 			f.campaigns[i].Subject = str(body["subject"])
 			f.campaigns[i].Body = str(body["body"])
+			f.campaigns[i].AltBody = str(body["altbody"])
 			f.campaigns[i].FromEmail = str(body["from_email"])
 			f.campaigns[i].TemplateID = toInt(body["template_id"])
 			f.campaigns[i].Type = str(body["type"])

internal/listmonk/listmonk.go

@@ -289,6 +289,7 @@ type Campaign struct {
 	Status     string
 	Subject    string
 	Body       string
+	AltBody    string
 	FromEmail  string
 	TemplateID int
 	Type       string
@@ -381,6 +382,7 @@ func parseCampaign(data []byte) (*Campaign, error) {
 		Status     string   `json:"status"`
 		Subject    string   `json:"subject"`
 		Body       string   `json:"body"`
+		AltBody    string   `json:"altbody"`
 		FromEmail  string   `json:"from_email"`
 		TemplateID int      `json:"template_id"`
 		Type       string   `json:"type"`
@@ -409,6 +411,7 @@ func parseCampaign(data []byte) (*Campaign, error) {
 		Status:     parsed.Status,
 		Subject:    parsed.Subject,
 		Body:       parsed.Body,
+		AltBody:    parsed.AltBody,
 		FromEmail:  parsed.FromEmail,
 		TemplateID: parsed.TemplateID,
 		Type:       parsed.Type,