feat: record events from the Journal API writes (D-102)

- POST/PUT/DELETE /_journal/api/v1/posts fire RecordSaved/RecordDeleted
  through cabana.EmitRecordSaved/EmitRecordDeleted, so a slug changed over
  MCP reaches subscribers like an admin save
- PUT reports the changed columns and each submitted translation that
  changed, read before the write (a translated slug per locale)
- TestAPIRecordEvents covers POST, PUT slug change and DELETE

controllers/api/posts.go

@@ -16,6 +16,7 @@ import (
 	"git.golem15.com/golem15/summercms/modules/cooler"
 	"git.golem15.com/golem15/summercms/modules/lagoon"
 	"git.golem15.com/golem15/summercms/modules/lagoon/attach"
+	"git.golem15.com/golem15/summercms/modules/pact"
 	"git.golem15.com/golem15/summercms/modules/wire"
 	"gocloud.dev/blob"
 	"gorm.io/gorm"
@@ -232,6 +233,7 @@ func Store(app *backpack.App) http.HandlerFunc {
 			return
 		}
 		purgeSiteCache(r, app, post)
+		cabana.EmitRecordSaved(r.Context(), app, nil, postSavedEvent(r.Context(), db.WithContext(r.Context()), nil, post, body))
 		wire.WriteJSON(w, http.StatusCreated, map[string]any{"data": serializePost(post, db.WithContext(r.Context()))})
 	}
 }
@@ -265,6 +267,9 @@ func Update(app *backpack.App) http.HandlerFunc {
 			writeAPIError(w, http.StatusBadRequest, errValidationFailed)
 			return
 		}
+		// D-92/D-102: the values before the write, for the RecordSaved
+		// subscribers hear (a slug changed over MCP gets its redirect).
+		before := snapshotPost(r.Context(), db.WithContext(r.Context()), post, body)
 		if verrs := applyPostUpdate(r, db.WithContext(r.Context()), post, body); verrs != nil {
 			writeValidation(w, verrs)
 			return
@@ -286,6 +291,7 @@ func Update(app *backpack.App) http.HandlerFunc {
 			return
 		}
 		purgeSiteCache(r, app, post)
+		cabana.EmitRecordSaved(r.Context(), app, nil, postSavedEvent(r.Context(), db.WithContext(r.Context()), before, post, body))
 		wire.WriteJSON(w, http.StatusOK, map[string]any{"data": serializePost(post, db.WithContext(r.Context()))})
 	}
 }
@@ -319,6 +325,10 @@ func Destroy(app *backpack.App) http.HandlerFunc {
 			return
 		}
 		purgeSiteCache(r, app, post)
+		cabana.EmitRecordDeleted(r.Context(), app, nil, pact.RecordDeleted{
+			Model: post.MorphName(),
+			ID:    strconv.FormatUint(uint64(post.ID), 10),
+		})
 		wire.WriteJSON(w, http.StatusOK, map[string]any{"message": msgPostDeleted})
 	}
 }

controllers/api/record_events.go

@@ -0,0 +1,161 @@
+package api
+
+import (
+	"context"
+	"reflect"
+	"sort"
+	"strconv"
+	"time"
+
+	"git.golem15.com/golem15/sm-journal-plugin/models"
+	translate "git.golem15.com/golem15/sm-translate-plugin/classes"
+	"git.golem15.com/golem15/summercms/modules/pact"
+	"git.golem15.com/golem15/summercms/modules/towel"
+	"gorm.io/gorm"
+)
+
+// postEventColumns are the post columns a record event reports, in order.
+var postEventColumns = []struct {
+	name  string
+	value func(p *models.Post) any
+}{
+	{"user_id", func(p *models.Post) any { return derefValue(p.UserID) }},
+	{"redactor_id", func(p *models.Post) any { return derefValue(p.RedactorID) }},
+	{"title", func(p *models.Post) any { return p.Title }},
+	{"slug", func(p *models.Post) any { return p.Slug }},
+	{"excerpt", func(p *models.Post) any { return p.Excerpt }},
+	{"content", func(p *models.Post) any { return p.Content }},
+	{"content_html", func(p *models.Post) any { return p.ContentHTML }},
+	{"published_at", func(p *models.Post) any { return derefValue(p.PublishedAt) }},
+	{"published", func(p *models.Post) any { return p.Published }},
+	{"is_pinned", func(p *models.Post) any { return p.IsPinned }},
+	{"metadata", func(p *models.Post) any { return derefValue(p.Metadata) }},
+	{"sources", func(p *models.Post) any { return derefValue(p.Sources) }},
+}
+
+// translatedEventFields are the translated fields a write may submit under
+// "translations" (syncTranslations).
+var translatedEventFields = []string{"title", "slug", "content", "content_html", "excerpt", "metadata"}
+
+// postSnapshot is a post's values before an API write: its columns and the
+// stored translations of the fields the request submits per locale.
+type postSnapshot struct {
+	columns      map[string]any
+	translations map[string]map[string]any // locale -> field -> old (nil when missing)
+}
+
+// snapshotPost takes the values an update may change, before it changes
+// them. A translation read error leaves that value out (reported as new).
+func snapshotPost(ctx context.Context, db *gorm.DB, post *models.Post, body map[string]any) *postSnapshot {
+	snap := &postSnapshot{columns: map[string]any{}, translations: map[string]map[string]any{}}
+	for _, col := range postEventColumns {
+		snap.columns[col.name] = col.value(post)
+	}
+	for locale, fields := range submittedTranslations(body) {
+		snap.translations[locale] = map[string]any{}
+		for _, field := range fields {
+			text, ok, err := translate.TranslatedExact(ctx, db, post, field, locale)
+			if err == nil && ok {
+				snap.translations[locale][field] = text
+			} else {
+				snap.translations[locale][field] = nil
+			}
+		}
+	}
+	return snap
+}
+
+// postSavedEvent is the RecordSaved of an API write, which the handler
+// fires with cabana.EmitRecordSaved once the write is committed (the API
+// writes run outside a transaction, so at once). before is nil on create:
+// every column with a value and every submitted translation is then
+// reported with a nil Old. Controller is "": the write did not go through an
+// admin form.
+func postSavedEvent(ctx context.Context, db *gorm.DB, before *postSnapshot, post *models.Post, body map[string]any) pact.RecordSaved {
+	changes := []pact.RecordChange{}
+	for _, col := range postEventColumns {
+		next := col.value(post)
+		if before == nil {
+			if next == nil || reflect.ValueOf(next).IsZero() {
+				continue
+			}
+			changes = append(changes, pact.RecordChange{Attribute: col.name, New: next})
+			continue
+		}
+		prev := before.columns[col.name]
+		if sameEventValue(prev, next) {
+			continue
+		}
+		changes = append(changes, pact.RecordChange{Attribute: col.name, Old: prev, New: next})
+	}
+	submitted := submittedTranslations(body)
+	locales := make([]string, 0, len(submitted))
+	for locale := range submitted {
+		locales = append(locales, locale)
+	}
+	sort.Strings(locales)
+	for _, locale := range locales {
+		for _, field := range submitted[locale] {
+			text, ok, err := translate.TranslatedExact(ctx, db, post, field, locale)
+			if err != nil || !ok {
+				continue
+			}
+			var prev any
+			if before != nil {
+				prev = before.translations[locale][field]
+			}
+			if old, _ := prev.(string); old == text {
+				continue
+			}
+			changes = append(changes, pact.RecordChange{Attribute: field, Locale: locale, Old: prev, New: text})
+		}
+	}
+	locale, _ := towel.Locale(ctx)
+	return pact.RecordSaved{
+		Model:   post.MorphName(),
+		ID:      strconv.FormatUint(uint64(post.ID), 10),
+		Locale:  locale,
+		Created: before == nil,
+		Changes: changes,
+	}
+}
+
+// submittedTranslations lists, per locale, the translated fields a request
+// body submits with a value, in translatedEventFields order.
+func submittedTranslations(body map[string]any) map[string][]string {
+	out := map[string][]string{}
+	m, ok := body["translations"].(map[string]any)
+	if !ok {
+		return out
+	}
+	for locale, raw := range m {
+		attrs, ok := raw.(map[string]any)
+		if !ok {
+			continue
+		}
+		for _, field := range translatedEventFields {
+			if v, has := attrs[field]; has && v != nil {
+				out[locale] = append(out[locale], field)
+			}
+		}
+	}
+	return out
+}
+
+// derefValue is a pointer column's value, nil for a nil pointer.
+func derefValue[T any](p *T) any {
+	if p == nil {
+		return nil
+	}
+	return *p
+}
+
+// sameEventValue compares two column values; times compare as instants.
+func sameEventValue(a, b any) bool {
+	ta, okA := a.(time.Time)
+	tb, okB := b.(time.Time)
+	if okA && okB {
+		return ta.Equal(tb)
+	}
+	return reflect.DeepEqual(a, b)
+}