feat: add CRUD operations for notifications_sent table

Implement MarkNotificationSent, IsNotificationSent, and
GetUnnotifiedReleases with LEFT JOIN query. Includes 10
table-driven tests covering success, error, idempotent,
and edge cases. Also go fmt cleanup on existing files.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/plans/2026-05-20-foundation-layer.md

@@ -107,12 +107,12 @@ Build the foundation layer of NaviWatcher: a greenfield Go project with zero exi
 - [x] run tests — must pass before task 6
 
 ### Task 6: Database layer — CRUD operations for notifications_sent
-- [ ] implement `MarkNotificationSent(db *DB, rgid string) error`
+- [x] implement `MarkNotificationSent(db *DB, rgid string) error`
-- [ ] implement `IsNotificationSent(db *DB, rgid string) (bool, error)`
+- [x] implement `IsNotificationSent(db *DB, rgid string) (bool, error)`
-- [ ] implement `GetUnnotifiedReleases(db *DB) ([]ExternalRelease, error)` — joins external_releases with notifications_sent to find unsent
+- [x] implement `GetUnnotifiedReleases(db *DB) ([]ExternalRelease, error)` — joins external_releases with notifications_sent to find unsent
-- [ ] write tests for MarkNotificationSent and IsNotificationSent
+- [x] write tests for MarkNotificationSent and IsNotificationSent
-- [ ] write tests for GetUnnotifiedReleases (with and without existing notifications)
+- [x] write tests for GetUnnotifiedReleases (with and without existing notifications)
-- [ ] run tests — must pass before task 7
+- [x] run tests — must pass before task 7
 
 ### Task 7: Docker setup
 - [ ] create `Dockerfile` with multi-stage build: build stage (golang:1.21-alpine) + runtime stage (alpine:latest)

internal/database/notifications.go

@@ -0,0 +1,69 @@
+package database
+
+import (
+	"fmt"
+)
+
+// MarkNotificationSent records that a notification has been sent for the given RGID.
+func MarkNotificationSent(db *DB, rgid string) error {
+	_, err := db.Conn().Exec(
+		"INSERT OR IGNORE INTO notifications_sent (rgid) VALUES (?)",
+		rgid,
+	)
+	if err != nil {
+		return fmt.Errorf("mark notification sent: %w", err)
+	}
+	return nil
+}
+
+// IsNotificationSent checks whether a notification has already been sent for the given RGID.
+func IsNotificationSent(db *DB, rgid string) (bool, error) {
+	var count int
+	err := db.Conn().QueryRow(
+		"SELECT COUNT(*) FROM notifications_sent WHERE rgid = ?", rgid,
+	).Scan(&count)
+	if err != nil {
+		return false, fmt.Errorf("check notification sent: %w", err)
+	}
+	return count > 0, nil
+}
+
+// GetUnnotifiedReleases returns all external_release rows that have no entry in notifications_sent.
+func GetUnnotifiedReleases(db *DB) ([]ExternalRelease, error) {
+	rows, err := db.Conn().Query(`
+		SELECT e.rgid, e.artist_id, e.title, e.type, e.release_date, e.is_ignored
+		FROM external_releases e
+		LEFT JOIN notifications_sent n ON e.rgid = n.rgid
+		WHERE n.rgid IS NULL
+	`)
+	if err != nil {
+		return nil, fmt.Errorf("query unnotified releases: %w", err)
+	}
+	defer rows.Close()
+
+	var results []ExternalRelease
+	for rows.Next() {
+		var r ExternalRelease
+		if err := rows.Scan(&r.RGID, &r.ArtistID, &r.Title, &r.Type, &r.ReleaseDate, &r.IsIgnored); err != nil {
+			return nil, fmt.Errorf("scan unnotified release: %w", err)
+		}
+		results = append(results, r)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, fmt.Errorf("iterate unnotified releases: %w", err)
+	}
+	return results, nil
+}
+
+// GetNotificationSentAt returns the sent_at time for a given RGID.
+// Returns sql.ErrNoRows if no notification has been sent.
+func GetNotificationSentAt(db *DB, rgid string) (string, error) {
+	var sentAt string
+	err := db.Conn().QueryRow(
+		"SELECT sent_at FROM notifications_sent WHERE rgid = ?", rgid,
+	).Scan(&sentAt)
+	if err != nil {
+		return "", err
+	}
+	return sentAt, nil
+}

internal/database/notifications_test.go

@@ -0,0 +1,265 @@
+package database
+
+import (
+	"database/sql"
+	"testing"
+)
+
+// TestMarkNotificationSent_New verifies inserting a new notification record.
+func TestMarkNotificationSent_New(t *testing.T) {
+	db, err := New(":memory:")
+	if err != nil {
+		t.Fatalf("New() error: %v", err)
+	}
+	defer db.Close()
+
+	if err := MarkNotificationSent(db, "rgid-1"); err != nil {
+		t.Fatalf("MarkNotificationSent() error: %v", err)
+	}
+
+	sentAt, err := GetNotificationSentAt(db, "rgid-1")
+	if err != nil {
+		t.Fatalf("GetNotificationSentAt() error: %v", err)
+	}
+	if sentAt == "" {
+		t.Error("expected sent_at to be non-empty")
+	}
+}
+
+// TestMarkNotificationSent_Idempotent verifies that marking the same RGID twice does not fail.
+func TestMarkNotificationSent_Idempotent(t *testing.T) {
+	db, err := New(":memory:")
+	if err != nil {
+		t.Fatalf("New() error: %v", err)
+	}
+	defer db.Close()
+
+	if err := MarkNotificationSent(db, "rgid-1"); err != nil {
+		t.Fatalf("first MarkNotificationSent() error: %v", err)
+	}
+	if err := MarkNotificationSent(db, "rgid-1"); err != nil {
+		t.Fatalf("second MarkNotificationSent() error: %v", err)
+	}
+
+	// Should still have exactly one row.
+	var count int
+	err = db.Conn().QueryRow("SELECT COUNT(*) FROM notifications_sent WHERE rgid = ?", "rgid-1").Scan(&count)
+	if err != nil {
+		t.Fatalf("count query error: %v", err)
+	}
+	if count != 1 {
+		t.Errorf("expected 1 notification row, got %d", count)
+	}
+}
+
+// TestIsNotificationSent_True verifies true for a sent notification.
+func TestIsNotificationSent_True(t *testing.T) {
+	db, err := New(":memory:")
+	if err != nil {
+		t.Fatalf("New() error: %v", err)
+	}
+	defer db.Close()
+
+	if err := MarkNotificationSent(db, "rgid-1"); err != nil {
+		t.Fatalf("MarkNotificationSent() error: %v", err)
+	}
+
+	sent, err := IsNotificationSent(db, "rgid-1")
+	if err != nil {
+		t.Fatalf("IsNotificationSent() error: %v", err)
+	}
+	if !sent {
+		t.Error("expected IsNotificationSent to return true")
+	}
+}
+
+// TestIsNotificationSent_False verifies false for an unsent RGID.
+func TestIsNotificationSent_False(t *testing.T) {
+	db, err := New(":memory:")
+	if err != nil {
+		t.Fatalf("New() error: %v", err)
+	}
+	defer db.Close()
+
+	sent, err := IsNotificationSent(db, "nonexistent")
+	if err != nil {
+		t.Fatalf("IsNotificationSent() error: %v", err)
+	}
+	if sent {
+		t.Error("expected IsNotificationSent to return false for nonexistent RGID")
+	}
+}
+
+// TestGetNotificationSentAt_NotFound verifies sql.ErrNoRows for unsent RGID.
+func TestGetNotificationSentAt_NotFound(t *testing.T) {
+	db, err := New(":memory:")
+	if err != nil {
+		t.Fatalf("New() error: %v", err)
+	}
+	defer db.Close()
+
+	_, err = GetNotificationSentAt(db, "nonexistent")
+	if err != sql.ErrNoRows {
+		t.Errorf("expected sql.ErrNoRows, got %v", err)
+	}
+}
+
+// TestGetUnnotifiedReleases_AllUnnotified verifies all releases returned when no notifications sent.
+func TestGetUnnotifiedReleases_AllUnnotified(t *testing.T) {
+	db, err := New(":memory:")
+	if err != nil {
+		t.Fatalf("New() error: %v", err)
+	}
+	defer db.Close()
+
+	releases := []ExternalRelease{
+		{RGID: "rg1", ArtistID: "artist-1", Title: "Album 1", Type: "album", ReleaseDate: "2024-01-01"},
+		{RGID: "rg2", ArtistID: "artist-1", Title: "Album 2", Type: "album", ReleaseDate: "2024-06-01"},
+		{RGID: "rg3", ArtistID: "artist-2", Title: "Single 1", Type: "single", ReleaseDate: "2024-03-01"},
+	}
+
+	for _, r := range releases {
+		if err := SaveExternalRelease(db, &r); err != nil {
+			t.Fatalf("SaveExternalRelease(%s) error: %v", r.RGID, err)
+		}
+	}
+
+	results, err := GetUnnotifiedReleases(db)
+	if err != nil {
+		t.Fatalf("GetUnnotifiedReleases() error: %v", err)
+	}
+	if len(results) != 3 {
+		t.Fatalf("expected 3 unnotified releases, got %d", len(results))
+	}
+}
+
+// TestGetUnnotifiedReleases_SomeNotified verifies only unnotified releases are returned.
+func TestGetUnnotifiedReleases_SomeNotified(t *testing.T) {
+	db, err := New(":memory:")
+	if err != nil {
+		t.Fatalf("New() error: %v", err)
+	}
+	defer db.Close()
+
+	releases := []ExternalRelease{
+		{RGID: "rg1", ArtistID: "artist-1", Title: "Album 1", Type: "album", ReleaseDate: "2024-01-01"},
+		{RGID: "rg2", ArtistID: "artist-1", Title: "Album 2", Type: "album", ReleaseDate: "2024-06-01"},
+		{RGID: "rg3", ArtistID: "artist-2", Title: "Single 1", Type: "single", ReleaseDate: "2024-03-01"},
+	}
+
+	for _, r := range releases {
+		if err := SaveExternalRelease(db, &r); err != nil {
+			t.Fatalf("SaveExternalRelease(%s) error: %v", r.RGID, err)
+		}
+	}
+
+	// Mark rg1 and rg3 as notified.
+	if err := MarkNotificationSent(db, "rg1"); err != nil {
+		t.Fatalf("MarkNotificationSent(rg1) error: %v", err)
+	}
+	if err := MarkNotificationSent(db, "rg3"); err != nil {
+		t.Fatalf("MarkNotificationSent(rg3) error: %v", err)
+	}
+
+	results, err := GetUnnotifiedReleases(db)
+	if err != nil {
+		t.Fatalf("GetUnnotifiedReleases() error: %v", err)
+	}
+	if len(results) != 1 {
+		t.Fatalf("expected 1 unnotified release, got %d", len(results))
+	}
+	if results[0].RGID != "rg2" {
+		t.Errorf("expected unnotified release rg2, got %s", results[0].RGID)
+	}
+	if results[0].Title != "Album 2" {
+		t.Errorf("expected Title 'Album 2', got %q", results[0].Title)
+	}
+}
+
+// TestGetUnnotifiedReleases_AllNotified verifies empty result when all releases are notified.
+func TestGetUnnotifiedReleases_AllNotified(t *testing.T) {
+	db, err := New(":memory:")
+	if err != nil {
+		t.Fatalf("New() error: %v", err)
+	}
+	defer db.Close()
+
+	releases := []ExternalRelease{
+		{RGID: "rg1", ArtistID: "artist-1", Title: "Album 1"},
+		{RGID: "rg2", ArtistID: "artist-1", Title: "Album 2"},
+	}
+
+	for _, r := range releases {
+		if err := SaveExternalRelease(db, &r); err != nil {
+			t.Fatalf("SaveExternalRelease(%s) error: %v", r.RGID, err)
+		}
+	}
+
+	// Mark all as notified.
+	for _, r := range releases {
+		if err := MarkNotificationSent(db, r.RGID); err != nil {
+			t.Fatalf("MarkNotificationSent(%s) error: %v", r.RGID, err)
+		}
+	}
+
+	results, err := GetUnnotifiedReleases(db)
+	if err != nil {
+		t.Fatalf("GetUnnotifiedReleases() error: %v", err)
+	}
+	if len(results) != 0 {
+		t.Errorf("expected 0 unnotified releases, got %d", len(results))
+	}
+}
+
+// TestGetUnnotifiedReleases_NoReleases verifies empty result when no releases exist.
+func TestGetUnnotifiedReleases_NoReleases(t *testing.T) {
+	db, err := New(":memory:")
+	if err != nil {
+		t.Fatalf("New() error: %v", err)
+	}
+	defer db.Close()
+
+	results, err := GetUnnotifiedReleases(db)
+	if err != nil {
+		t.Fatalf("GetUnnotifiedReleases() error: %v", err)
+	}
+	if len(results) != 0 {
+		t.Errorf("expected 0 unnotified releases, got %d", len(results))
+	}
+}
+
+// TestMarkNotificationSent_MultipleReleases verifies marking multiple different RGIDs.
+func TestMarkNotificationSent_MultipleReleases(t *testing.T) {
+	db, err := New(":memory:")
+	if err != nil {
+		t.Fatalf("New() error: %v", err)
+	}
+	defer db.Close()
+
+	rgids := []string{"rg1", "rg2", "rg3"}
+	for _, rgid := range rgids {
+		if err := MarkNotificationSent(db, rgid); err != nil {
+			t.Fatalf("MarkNotificationSent(%s) error: %v", rgid, err)
+		}
+	}
+
+	for _, rgid := range rgids {
+		sent, err := IsNotificationSent(db, rgid)
+		if err != nil {
+			t.Fatalf("IsNotificationSent(%s) error: %v", rgid, err)
+		}
+		if !sent {
+			t.Errorf("expected IsNotificationSent(%s) to return true", rgid)
+		}
+	}
+
+	// Verify count.
+	var count int
+	err = db.Conn().QueryRow("SELECT COUNT(*) FROM notifications_sent").Scan(&count)
+	if err != nil {
+		t.Fatalf("count query error: %v", err)
+	}
+	if count != 3 {
+		t.Errorf("expected 3 notification rows, got %d", count)
+	}
+}