Latest Chapter provenance line naming the actor class (#152)

backend/internal/web/admin_series_detail.go

@@ -33,6 +33,12 @@ type seriesDetailView struct {
 	// owner's, and it dies with the stamp (a machine write of the number).
 	Corrected string
 
+	// Provenance is the actor class behind the current Chapter: "correction",
+	// "sighting" or "machine read"; "" while the Series was never read, when
+	// the line is not rendered. Derived from the same anonymous stamps the
+	// marks above read — no Reader identity crosses here.
+	Provenance string
+
 	// Marks, one per hygiene fact, rendered only while it holds.
 	Unpollable     bool // no SeriesURL to fetch
 	NoCover        bool
@@ -130,6 +136,24 @@ func (h *Handler) seriesDetailView(a store.AdminSeries) seriesDetailView {
 		v.Checked = since(time.Now(), time.UnixMilli(a.LatestCheckedAt))
 	}
 	v.Corrected = correctedAge(time.Now(), a.LatestCorrectedAt)
+
+	// Provenance: the actor class behind the current number, evaluated in the
+	// order the classes outrank one another — the owner's stamp, which a
+	// Correction leaves standing and a machine write clears (issue #149); a
+	// raising Reader, which a Correction drops; then any check stamp at all.
+	// An Acquisition reads as a machine read because it stamps
+	// latest_checked_at exactly as a Poll does, so the two are
+	// indistinguishable the moment it finishes; telling them apart would need
+	// the column this project declines to add (spec #135), and the one
+	// actionable case — acquired once, never read again — is already the
+	// unchecked filter.
+	if a.LatestCorrectedAt != 0 {
+		v.Provenance = "correction"
+	} else if a.RaisedByReader {
+		v.Provenance = "sighting"
+	} else if a.LatestCheckedAt != 0 {
+		v.Provenance = "machine read"
+	}
 	return v
 }