feat(web): real channel filter — multi-select of the user's channels

The free-text 'channel' filter was dead: it exact-matched SummaryRow.Channel,
which is just the provider ('youtube'), because videos never stored their source
channel. Now they do.

- migration 014: videos.channel_title (nullable; existing rows backfill on the
  next discovery pass, pasted videos immediately).
- discovery (NewVideos) + paste (VideoByID) populate channel_title; UpsertVideo
  persists it, preserving an existing title when an update arrives empty.
- store.DistinctChannels lists a user's channels (RLS-scoped); SummaryRow carries
  ChannelTitle via the shared projection.
- Filter: single Channel -> Channels []string, matching on ChannelTitle; the feed
  renders a multi-select of DistinctChannels (hidden until channels exist).
- migrate tests: 014 reversibility + fixed the relative-step counts in the 010/011
  up/down tests (014 shifted the topology).

TDD throughout: channel persist + distinct, adapter channel wiring, multi-channel
filter match, handler channel filter, migration up/down.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/adapters/store/migrate_test.go

@@ -53,7 +53,9 @@ func TestMigration010LoginEventsUpDown(t *testing.T) {
 	require.True(t, loginEventsExists(t), "login_events must exist at latest migration")
 
 	m := fileMigrator(t)
-	// 011, 012, 013 sit above 010; step them down first so 010 is exercised in isolation.
+	// 011, 012, 013, 014 sit above 010; step them down first so 010 is exercised in isolation.
+	require.NoError(t, m.Steps(-1), "down 014 drops channel_title, login_events intact")
+	require.True(t, loginEventsExists(t), "014 down leaves login_events intact")
 	require.NoError(t, m.Steps(-1), "down 013 drops channel_errors, login_events intact")
 	require.True(t, loginEventsExists(t), "013 down leaves login_events intact")
 	require.NoError(t, m.Steps(-1), "down 012 is a no-op, login_events intact")
@@ -64,7 +66,7 @@ func TestMigration010LoginEventsUpDown(t *testing.T) {
 	require.NoError(t, m.Steps(-1), "down 010 must drop login_events")
 	require.False(t, loginEventsExists(t), "login_events must be gone after the down migration")
 
-	require.NoError(t, m.Steps(4), "up must recreate 010 then re-apply 011, 012, 013")
+	require.NoError(t, m.Steps(5), "up must recreate 010 then re-apply 011, 012, 013, 014")
 	require.True(t, loginEventsExists(t), "login_events must be restored after the up migration")
 }
 
@@ -87,6 +89,7 @@ func TestMigration011AutoSummarizeDefaultUpDown(t *testing.T) {
 	require.Equal(t, "true", autoSummarizeDefault(t), "011 sets the default to TRUE")
 
 	m := fileMigrator(t)
+	require.NoError(t, m.Steps(-1), "down 014 drops channel_title")
 	require.NoError(t, m.Steps(-1), "down 013 drops channel_errors")
 	require.NoError(t, m.Steps(-1), "down 012 is a no-op")
 	require.NoError(t, m.Steps(-1), "down 011 reverts the column default")
@@ -96,6 +99,31 @@ func TestMigration011AutoSummarizeDefaultUpDown(t *testing.T) {
 	require.Equal(t, "true", autoSummarizeDefault(t))
 	require.NoError(t, m.Steps(1), "up 012 runs clean (no FORCE RLS on fresh schema)")
 	require.NoError(t, m.Steps(1), "up 013 creates channel_errors")
+	require.NoError(t, m.Steps(1), "up 014 recreates channel_title")
+}
+
+// channelTitleExists reports whether videos.channel_title is present.
+func channelTitleExists(t *testing.T) bool {
+	t.Helper()
+	var exists bool
+	require.NoError(t, rawPool(t).QueryRow(context.Background(),
+		`SELECT EXISTS (SELECT 1 FROM information_schema.columns
+		  WHERE table_name = 'videos' AND column_name = 'channel_title')`).Scan(&exists))
+	return exists
+}
+
+// TestMigration014VideoChannelTitleUpDown proves 014 is reversible: down drops
+// videos.channel_title, up recreates it.
+func TestMigration014VideoChannelTitleUpDown(t *testing.T) {
+	newStore(t) // latest (014 applied)
+	require.True(t, channelTitleExists(t), "channel_title exists at latest migration")
+
+	m := fileMigrator(t)
+	require.NoError(t, m.Steps(-1), "down 014 must drop channel_title")
+	require.False(t, channelTitleExists(t), "channel_title must be gone after the down migration")
+
+	require.NoError(t, m.Steps(1), "up 014 must recreate channel_title")
+	require.True(t, channelTitleExists(t), "channel_title must be restored after the up migration")
 }
 
 // TestMigration012FixAutoSummarizeRLS proves 012 runs cleanly and flips any

internal/adapters/store/migrations/014_video_channel_title.down.sql

@@ -0,0 +1 @@
+ALTER TABLE videos DROP COLUMN channel_title;

internal/adapters/store/migrations/014_video_channel_title.up.sql

@@ -0,0 +1,8 @@
+-- Store the source channel's title per video so the list can offer a real
+-- channel filter (multi-select of the user's channels) instead of the dead
+-- free-text field that only ever matched the provider string. Nullable: existing
+-- rows backfill on the next discovery pass (UpsertVideo writes it); pasted videos
+-- get it immediately from videos.list. No FK to a channels table at Stage 0 — the
+-- title is a denormalised display/filter value, consistent with the existing
+-- subscription_id-stays-NULL stance (data-model.md).
+ALTER TABLE videos ADD COLUMN channel_title TEXT;

internal/adapters/store/reads.go

@@ -29,6 +29,7 @@ type SummaryRow struct {
 	ProviderVideoID string    // videos.provider_video_id; empty when no videos row
 	Title           string    // videos.title; empty when no videos row
 	Channel         string    // videos.provider for now; empty when no videos row
+	ChannelTitle    string    // videos.channel_title; the source channel, for display + filtering
 	URL             string    // videos.url; empty when no videos row
 	PublishedAt     time.Time // videos.published_at; zero when absent
 	Summary         string
@@ -137,7 +138,8 @@ const selectVideo = `
 	       COALESCE(s.created_at, v.seen_at),
 	       (s.id IS NOT NULL) AS summarized,
 	       v.summarize_requested,
-	       COALESCE(v.transcript_status, '')
+	       COALESCE(v.transcript_status, ''),
+	       COALESCE(v.channel_title, '')
 	  FROM videos v
 	  LEFT JOIN summaries s ON s.video_id = v.id AND s.user_id = v.user_id`
 
@@ -254,6 +256,7 @@ func scanVideoRow(rows pgx.Row) (SummaryRow, error) {
 		&row.Summarized,
 		&row.SummarizeRequested,
 		&row.TranscriptStatus,
+		&row.ChannelTitle,
 	); err != nil {
 		return SummaryRow{}, fmt.Errorf("store: scan video: %w", err)
 	}

internal/adapters/store/videos.go

@@ -46,14 +46,15 @@ func (s *Store) UpsertVideo(ctx context.Context, v domain.Video) (string, error)
 		}
 
 		if err := tx.QueryRow(ctx,
-			`INSERT INTO videos (user_id, provider, provider_video_id, title, url, published_at)
-			 VALUES ($1, $2, $3, $4, $5, $6)
+			`INSERT INTO videos (user_id, provider, provider_video_id, title, url, published_at, channel_title)
+			 VALUES ($1, $2, $3, $4, $5, $6, $7)
 			 ON CONFLICT (user_id, provider, provider_video_id) DO UPDATE SET
-			     title        = EXCLUDED.title,
-			     url          = EXCLUDED.url,
-			     published_at = EXCLUDED.published_at
+			     title         = EXCLUDED.title,
+			     url           = EXCLUDED.url,
+			     published_at  = EXCLUDED.published_at,
+			     channel_title = COALESCE(NULLIF(EXCLUDED.channel_title, ''), videos.channel_title)
 			 RETURNING id`,
-			v.UserID, provider, v.ProviderVideoID, v.Title, v.URL, nullTime(v.PublishedAt),
+			v.UserID, provider, v.ProviderVideoID, v.Title, v.URL, nullTime(v.PublishedAt), v.ChannelTitle,
 		).Scan(&id); err != nil {
 			return fmt.Errorf("store: upsert video: %w", err)
 		}
@@ -110,3 +111,31 @@ func (s *Store) NewestUnsummarizedVideoIDs(ctx context.Context, userID string, l
 	}
 	return ids, nil
 }
+
+// DistinctChannels returns the user's distinct, non-empty source channel titles
+// (the channels they have videos from), alphabetically — the option list for the
+// feed's channel filter. RLS-scoped via withUser.
+func (s *Store) DistinctChannels(ctx context.Context, userID string) ([]string, error) {
+	var out []string
+	if err := s.withUser(ctx, userID, func(tx pgx.Tx) error {
+		rows, err := tx.Query(ctx,
+			`SELECT DISTINCT channel_title FROM videos
+			  WHERE user_id = $1 AND channel_title IS NOT NULL AND channel_title <> ''
+			  ORDER BY channel_title`, userID)
+		if err != nil {
+			return fmt.Errorf("store: distinct channels: %w", err)
+		}
+		defer rows.Close()
+		for rows.Next() {
+			var c string
+			if err := rows.Scan(&c); err != nil {
+				return fmt.Errorf("store: scan channel: %w", err)
+			}
+			out = append(out, c)
+		}
+		return rows.Err()
+	}); err != nil {
+		return nil, err
+	}
+	return out, nil
+}

internal/adapters/store/videos_test.go

@@ -113,3 +113,29 @@ func TestNewestUnsummarizedVideoIDs(t *testing.T) {
 	require.NoError(t, err)
 	require.Empty(t, none, "limit 0 returns nothing")
 }
+
+func TestUpsertVideoPersistsChannelAndDistinctChannels(t *testing.T) {
+	ctx := context.Background()
+	s := newStore(t)
+	resetDB(t, rawPool(t))
+
+	mk := func(pid, channel string) {
+		v := ytVideo(userA, pid, pid)
+		v.ChannelTitle = channel
+		_, err := s.UpsertVideo(ctx, v)
+		require.NoError(t, err)
+	}
+	mk("aa11111aaaa", "Acme Talks")
+	mk("bb22222bbbb", "Acme Talks") // same channel
+	mk("cc33333cccc", "Zeta Channel")
+	// userB's channel must not leak.
+	vb := ytVideo(userB, "dd44444dddd", "x")
+	vb.ChannelTitle = "Bravo Only"
+	_, err := s.UpsertVideo(ctx, vb)
+	require.NoError(t, err)
+
+	got, err := s.DistinctChannels(ctx, userA)
+	require.NoError(t, err)
+	require.Equal(t, []string{"Acme Talks", "Zeta Channel"}, got,
+		"distinct, alphabetical, user-scoped (no Bravo Only)")
+}

internal/adapters/youtube/videobyid_test.go

@@ -21,7 +21,7 @@ func TestVideoByID(t *testing.T) {
 		if got := r.URL.Query().Get("part"); got != "snippet" {
 			t.Errorf("expected part=snippet, got %q", got)
 		}
-		_, _ = w.Write([]byte(`{"items":[{"snippet":{"title":"Never Gonna Give You Up","publishedAt":"2026-05-20T09:00:00Z"}}]}`))
+		_, _ = w.Write([]byte(`{"items":[{"snippet":{"title":"Never Gonna Give You Up","channelTitle":"Rick Astley","publishedAt":"2026-05-20T09:00:00Z"}}]}`))
 	})
 
 	v, err := a.VideoByID(context.Background(), "u1", id)
@@ -34,6 +34,9 @@ func TestVideoByID(t *testing.T) {
 	if v.ProviderVideoID != id || v.Title != "Never Gonna Give You Up" {
 		t.Errorf("unexpected video: %+v", v)
 	}
+	if v.ChannelTitle != "Rick Astley" {
+		t.Errorf("ChannelTitle = %q, want Rick Astley", v.ChannelTitle)
+	}
 	if v.Provider != domain.ProviderYouTube || v.URL != "https://www.youtube.com/watch?v="+id {
 		t.Errorf("video not wired correctly: %+v", v)
 	}

internal/adapters/youtube/youtube.go

@@ -234,6 +234,7 @@ func (a *Adapter) NewVideos(ctx context.Context, sub domain.Subscription) ([]dom
 			Provider:        domain.ProviderYouTube,
 			ProviderVideoID: vid,
 			Title:           item.Snippet.Title,
+			ChannelTitle:    sub.ChannelTitle,
 			URL:             "https://www.youtube.com/watch?v=" + vid,
 			PublishedAt:     item.Snippet.PublishedAt,
 		})
@@ -270,6 +271,7 @@ func (a *Adapter) VideoByID(ctx context.Context, userID, videoID string) (domain
 		Provider:        domain.ProviderYouTube,
 		ProviderVideoID: videoID,
 		Title:           it.Snippet.Title,
+		ChannelTitle:    it.Snippet.ChannelTitle,
 		URL:             "https://www.youtube.com/watch?v=" + videoID,
 		PublishedAt:     it.Snippet.PublishedAt,
 	}, nil
@@ -376,8 +378,9 @@ type playlistItemListResponse struct {
 type videoListResponse struct {
 	Items []struct {
 		Snippet struct {
-			Title       string    `json:"title"`
-			PublishedAt time.Time `json:"publishedAt"`
+			Title        string    `json:"title"`
+			ChannelTitle string    `json:"channelTitle"`
+			PublishedAt  time.Time `json:"publishedAt"`
 		} `json:"snippet"`
 	} `json:"items"`
 }

internal/adapters/youtube/youtube_test.go

@@ -131,7 +131,7 @@ func TestNewVideos(t *testing.T) {
 		}`))
 	})
 
-	sub := domain.Subscription{ID: "s1", UserID: "u1", ChannelID: "UC_acme"}
+	sub := domain.Subscription{ID: "s1", UserID: "u1", ChannelID: "UC_acme", ChannelTitle: "Acme Channel"}
 	vids, err := a.NewVideos(context.Background(), sub)
 	if err != nil {
 		t.Fatalf("NewVideos: %v", err)
@@ -143,6 +143,9 @@ func TestNewVideos(t *testing.T) {
 	if v.ProviderVideoID != "vid1" || v.Title != "Designing for Attention" {
 		t.Errorf("unexpected video: %+v", v)
 	}
+	if v.ChannelTitle != "Acme Channel" {
+		t.Errorf("ChannelTitle = %q, want Acme Channel", v.ChannelTitle)
+	}
 	if v.Provider != domain.ProviderYouTube || v.URL != "https://www.youtube.com/watch?v=vid1" {
 		t.Errorf("video not wired correctly: %+v", v)
 	}