fix: report the old translated content_html on API post events

syncTranslations adds content_html to a translation that sends content, after
snapshotPost read the old values, so the event saw content_html as newly
submitted and reported Old: nil for a translation that existed.
submittedTranslations now lists content_html whenever a non-blank content is
sent, so the snapshot and the event cover the same fields.

controllers/api/record_events.go

@@ -2,9 +2,11 @@ package api
 
 import (
 	"context"
+	"fmt"
 	"reflect"
 	"sort"
 	"strconv"
+	"strings"
 	"time"
 
 	"git.golem15.com/golem15/sm-journal-plugin/models"
@@ -121,7 +123,11 @@ func postSavedEvent(ctx context.Context, db *gorm.DB, before *postSnapshot, post
 }
 
 // submittedTranslations lists, per locale, the translated fields a request
-// body submits with a value, in translatedEventFields order.
+// body submits with a value, in translatedEventFields order. content_html is
+// listed whenever a non-blank content is, as the write derives it from the
+// content (classes.FormatTranslation): the snapshot before the write and the
+// event after it then cover the same fields, whether or not the write has
+// already added content_html to the body.
 func submittedTranslations(body map[string]any) map[string][]string {
 	out := map[string][]string{}
 	m, ok := body["translations"].(map[string]any)
@@ -134,7 +140,8 @@ func submittedTranslations(body map[string]any) map[string][]string {
 			continue
 		}
 		for _, field := range translatedEventFields {
-			if v, has := attrs[field]; has && v != nil {
+			v, has := attrs[field]
+			if (has && v != nil) || (field == "content_html" && derivesContentHTML(attrs)) {
 				out[locale] = append(out[locale], field)
 			}
 		}
@@ -142,6 +149,13 @@ func submittedTranslations(body map[string]any) map[string][]string {
 	return out
 }
 
+// derivesContentHTML reports whether a translation's attributes carry a
+// content the write turns into content_html (a non-blank value).
+func derivesContentHTML(attrs map[string]any) bool {
+	content, has := attrs["content"]
+	return has && content != nil && strings.TrimSpace(fmt.Sprint(content)) != ""
+}
+
 // derefValue is a pointer column's value, nil for a nil pointer.
 func derefValue[T any](p *T) any {
 	if p == nil {

record_events_test.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"net/http"
+	"strings"
 	"sync"
 	"testing"
 
@@ -239,6 +240,24 @@ func TestAPIRecordEvents(t *testing.T) {
 		t.Fatalf("PUT described URL = %q", got[0].url)
 	}
 
+	// A translated content derives its content_html: the event reports the
+	// stored content_html as Old, not nil (WR-05).
+	env.expect(t, http.StatusOK, http.MethodPut, "/_journal/api/v1/posts/"+id, token, map[string]any{
+		"translations": map[string]any{"pl": map[string]any{"content": "Stara treść"}},
+	})
+	l.reset()
+	env.expect(t, http.StatusOK, http.MethodPut, "/_journal/api/v1/posts/"+id, token, map[string]any{
+		"translations": map[string]any{"pl": map[string]any{"content": "Nowa treść"}},
+	})
+	got = l.savedEvents()
+	if len(got) != 1 {
+		t.Fatalf("PUT content events = %+v, want one RecordSaved", got)
+	}
+	html, ok := findChange(got[0].ev.Changes, "content_html", "pl")
+	if old, _ := html.Old.(string); !ok || !strings.Contains(old, "Stara") || !strings.Contains(fmt.Sprint(html.New), "Nowa") {
+		t.Fatalf("pl content_html change = %+v (found %v); changes %+v", html, ok, got[0].ev.Changes)
+	}
+
 	// A write that fails after the row is saved rolls the row back and
 	// fires nothing (WR-04).
 	l.reset()