3 files changed, 82 insertions, 0 deletions
diff --git a/internal/calfeed/calfeed.go b/internal/calfeed/calfeed.go
new file mode 100644
index 0000000..cb2a8ff
--- /dev/null
+++ b/internal/calfeed/calfeed.go
@@ -0,0 +1,30 @@
+package calfeed
+
+type ReadingView struct {
+	Part     string `json:"part"`
+	Citation string `json:"citation"`
+}
+
+type CelView struct {
+	Slug  string `json:"slug"`
+	Name  string `json:"name"`
+	Rank  string `json:"rank"`
+	Class int    `json:"class"`
+}
+
+type DayView struct {
+	Date     string        `json:"date"` // YYYY-MM-DD
+	Season   string        `json:"season"`
+	Week     int           `json:"week"`
+	Weekday  string        `json:"weekday"`
+	Colour   string        `json:"colour"`
+	Observed CelView       `json:"observed"`
+	Others   []CelView     `json:"others"`
+	Cycles   Cycles        `json:"cycles"`
+	Readings []ReadingView `json:"readings"`
+}
+
+type Cycles struct {
+	Sunday  string `json:"sunday"`
+	Weekday string `json:"weekday"`
+}
diff --git a/internal/calfeed/json.go b/internal/calfeed/json.go
new file mode 100644
index 0000000..c1a50ca
--- /dev/null
+++ b/internal/calfeed/json.go
@@ -0,0 +1,17 @@
+package calfeed
+
+import "encoding/json"
+
+const Schema = "lectio.calendar/1"
+
+// JSON renders days as the stable lectio.calendar/1 envelope.
+func JSON(form string, days []DayView) ([]byte, error) {
+	if days == nil {
+		days = []DayView{}
+	}
+	return json.MarshalIndent(struct {
+		Schema string    `json:"schema"`
+		Form   string    `json:"form"`
+		Days   []DayView `json:"days"`
+	}{Schema, form, days}, "", "  ")
+}
diff --git a/internal/calfeed/json_test.go b/internal/calfeed/json_test.go
new file mode 100644
index 0000000..d2bc856
--- /dev/null
+++ b/internal/calfeed/json_test.go
@@ -0,0 +1,35 @@
+package calfeed
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+func TestJSONShape(t *testing.T) {
+	days := []DayView{{
+		Date: "2026-01-06", Season: "time-after-epiphany", Week: 1,
+		Weekday: "Tuesday", Colour: "white",
+		Observed: CelView{Slug: "ef-epiphany", Name: "The Epiphany of the Lord", Rank: "class-1", Class: 1},
+		Others:   []CelView{},
+		Cycles:   Cycles{},
+		Readings: []ReadingView{{Part: "gospel", Citation: "Matt 2:1-12"}},
+	}}
+	b, err := JSON("old", days)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var out struct {
+		Schema string    `json:"schema"`
+		Form   string    `json:"form"`
+		Days   []DayView `json:"days"`
+	}
+	if err := json.Unmarshal(b, &out); err != nil {
+		t.Fatal(err)
+	}
+	if out.Schema != "lectio.calendar/1" || out.Form != "old" || len(out.Days) != 1 {
+		t.Fatalf("bad envelope: %s", b)
+	}
+	if out.Days[0].Observed.Name != "The Epiphany of the Lord" {
+		t.Fatalf("bad day: %s", b)
+	}
+}