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/web/handlers.go

@@ -21,6 +21,9 @@ import (
 // fake without a database.
 type Store interface {
 	ListVideos(ctx context.Context, userID string, limit int) ([]store.SummaryRow, error)
+	// DistinctChannels lists the user's source channels — the options for the
+	// feed's channel multi-select filter.
+	DistinctChannels(ctx context.Context, userID string) ([]string, error)
 	GetSummaryByVideo(ctx context.Context, userID, videoID string) (*store.SummaryRow, error)
 	GetVideoRow(ctx context.Context, userID, videoID string) (*store.SummaryRow, error)
 	ActionsFor(ctx context.Context, userID string, videoIDs []string) (map[string][]string, error)
@@ -196,7 +199,7 @@ func (a *App) handleList(w http.ResponseWriter, r *http.Request) {
 	}
 	q := r.URL.Query()
 	f := Filter{
-		Channel:        q.Get("channel"),
+		Channels:       nonEmptyStrings(q["channel"]),
 		From:           q.Get("from"),
 		To:             q.Get("to"),
 		OnlySummarized: q.Get("summarized") == "1",
@@ -211,6 +214,13 @@ func (a *App) handleList(w http.ResponseWriter, r *http.Request) {
 	rows := f.apply(allRows)
 	buckets := bucketRows(rows, a.recencyCutoff())
 
+	// Channel options for the multi-select filter (the user's source channels).
+	channels, err := a.Store.DistinctChannels(r.Context(), userID)
+	if err != nil {
+		a.serverError(w, r, "distinct channels", err)
+		return
+	}
+
 	// hasConnected drives both the paste box (shown to ANY connected user, #2) and
 	// the empty-state copy (a fresh account with a connection but no discovery pass
 	// yet reads "connected, summaries land gradually" rather than "nothing here").
@@ -227,7 +237,7 @@ func (a *App) handleList(w http.ResponseWriter, r *http.Request) {
 		a.render(w, r, summaryList(buckets, hasConnected))
 		return
 	}
-	a.render(w, r, ListPage(buckets, f, stats, takeFlash(w, r), hasConnected))
+	a.render(w, r, ListPage(buckets, f, stats, takeFlash(w, r), hasConnected, channels))
 }
 
 // handleDetail renders one summary in full (highlights, takeaways, action group).

internal/web/handlers_test.go

@@ -207,13 +207,15 @@ func TestListChannelFilter(t *testing.T) {
 	resetDB(t, p)
 	require.NoError(t, deliver(ctx, app, videoX, "body x"))
 	seedVideo(t, p, videoX, "X Title", "https://x", time.Time{})
+	_, err := p.Exec(ctx, `UPDATE videos SET channel_title = 'Acme Channel' WHERE id = $1`, videoX)
+	require.NoError(t, err)
 
-	// Channel is "youtube" for seeded rows; a non-matching filter hides them.
-	rec := do(t, app, httptest.NewRequest(http.MethodGet, "/?channel=vimeo", nil))
+	// Selecting a different channel hides the row; selecting its channel shows it.
+	rec := do(t, app, httptest.NewRequest(http.MethodGet, "/?channel=Other+Channel", nil))
 	require.Equal(t, http.StatusOK, rec.Code)
 	require.NotContains(t, body(t, rec), "X Title")
 
-	rec = do(t, app, httptest.NewRequest(http.MethodGet, "/?channel=youtube", nil))
+	rec = do(t, app, httptest.NewRequest(http.MethodGet, "/?channel=Acme+Channel", nil))
 	require.Contains(t, body(t, rec), "X Title")
 }
 

internal/web/paste_test.go

@@ -3,6 +3,7 @@ package web
 import (
 	"bytes"
 	"context"
+	"gitea.d-ma.be/mathias/tapir/internal/adapters/store"
 	"strings"
 	"testing"
 )
@@ -64,7 +65,7 @@ func TestParseYouTubeVideoID(t *testing.T) {
 func TestListPageShowsPasteFormOnlyWhenConnected(t *testing.T) {
 	render := func(connected bool) string {
 		var buf bytes.Buffer
-		if err := ListPage(listBuckets{}, Filter{}, PipelineStats{}, "", connected).Render(context.Background(), &buf); err != nil {
+		if err := ListPage(listBuckets{}, Filter{}, PipelineStats{}, "", connected, nil).Render(context.Background(), &buf); err != nil {
 			t.Fatalf("render: %v", err)
 		}
 		return buf.String()
@@ -78,3 +79,19 @@ func TestListPageShowsPasteFormOnlyWhenConnected(t *testing.T) {
 		t.Errorf("disconnected feed must not show the paste form")
 	}
 }
+
+func TestFilterMatchesMultipleChannels(t *testing.T) {
+	f := Filter{Channels: []string{"Acme", "Zeta"}}
+	row := func(ch string) store.SummaryRow { return store.SummaryRow{ChannelTitle: ch, Summarized: true} }
+
+	rows := []store.SummaryRow{row("Acme"), row("Beta"), row("Zeta")}
+	got := f.apply(rows)
+	if len(got) != 2 || got[0].ChannelTitle != "Acme" || got[1].ChannelTitle != "Zeta" {
+		t.Fatalf("multi-channel filter = %+v, want Acme+Zeta only", got)
+	}
+
+	// Empty selection = no channel constraint (all pass).
+	if n := len(Filter{}.apply(rows)); n != 3 {
+		t.Fatalf("no channel filter should pass all rows, got %d", n)
+	}
+}

internal/web/view.go

@@ -2,6 +2,7 @@ package web
 
 import (
 	"regexp"
+	"slices"
 	"strings"
 	"time"
 	"unicode/utf8"
@@ -469,7 +470,7 @@ func (b listBuckets) empty() bool {
 // Dates are kept as the raw YYYY-MM-DD strings so the form re-renders the user's
 // input verbatim; parsing happens in matchFilter.
 type Filter struct {
-	Channel        string
+	Channels       []string // selected channel titles; empty = all channels
 	From           string
 	To             string
 	OnlySummarized bool // show only videos that have a summary
@@ -480,7 +481,28 @@ type Filter struct {
 // filter) the bar is hidden so the connect CTA stands alone (UX review C1); a
 // filter that happens to match nothing still shows the bar so it can be cleared.
 func (f Filter) active() bool {
-	return f.Channel != "" || f.From != "" || f.To != "" || f.OnlySummarized
+	return len(f.Channels) > 0 || f.From != "" || f.To != "" || f.OnlySummarized
+}
+
+// HasChannel reports whether a channel is currently selected (drives the
+// multi-select's selected state in the view).
+func (f Filter) HasChannel(c string) bool {
+	return slices.Contains(f.Channels, c)
+}
+
+// nonEmptyStrings drops blank entries. A channel multi-select submits real
+// channel titles; this guards against a stray empty value reaching the filter.
+func nonEmptyStrings(ss []string) []string {
+	out := ss[:0:0]
+	for _, s := range ss {
+		if strings.TrimSpace(s) != "" {
+			out = append(out, s)
+		}
+	}
+	if len(out) == 0 {
+		return nil
+	}
+	return out
 }
 
 // matches reports whether a row satisfies the filter. Channel is an exact match;
@@ -491,7 +513,7 @@ func (f Filter) matches(r store.SummaryRow) bool {
 	if f.OnlySummarized && !r.Summarized {
 		return false
 	}
-	if f.Channel != "" && r.Channel != f.Channel {
+	if len(f.Channels) > 0 && !slices.Contains(f.Channels, r.ChannelTitle) {
 		return false
 	}
 	if from, ok := parseDate(f.From); ok {
@@ -521,7 +543,7 @@ func parseDate(s string) (time.Time, bool) {
 
 // apply returns the subset of rows matching the filter, preserving order.
 func (f Filter) apply(rows []store.SummaryRow) []store.SummaryRow {
-	if f.Channel == "" && f.From == "" && f.To == "" && !f.OnlySummarized {
+	if len(f.Channels) == 0 && f.From == "" && f.To == "" && !f.OnlySummarized {
 		return rows
 	}
 	out := rows[:0:0]

internal/web/views.templ

@@ -104,14 +104,14 @@ templ flashBanner(code string) {
 // #summary-list region; a non-HTMX request renders the whole page. flash carries
 // a one-shot notification (e.g. "connected", "registered") surfaced on arrival
 // after a POST→redirect.
-templ ListPage(b listBuckets, f Filter, stats PipelineStats, flash string, hasConnected bool) {
+templ ListPage(b listBuckets, f Filter, stats PipelineStats, flash string, hasConnected bool, channels []string) {
 	@Layout("Tapir — Summaries") {
 		@flashBanner(flash)
 		if hasConnected {
 			@pasteForm()
 		}
 		if !b.empty() || f.active() {
-			@filterForm(f)
+			@filterForm(f, channels)
 		}
 		if stats.RateLimited > 0 || stats.Pending > 0 || stats.NoText > 0 {
 			@pipelineBar(stats)
@@ -168,7 +168,7 @@ templ pasteForm() {
 	<div id="paste-result"></div>
 }
 
-templ filterForm(f Filter) {
+templ filterForm(f Filter, channels []string) {
 	<form
 		class="filters"
 		method="get"
@@ -178,7 +178,16 @@ templ filterForm(f Filter) {
 		hx-swap="innerHTML"
 		hx-indicator="#filter-indicator"
 	>
-		<label>Channel <input type="text" name="channel" value={ f.Channel } placeholder="any"/></label>
+		if len(channels) > 0 {
+			<label>
+				Channels
+				<select name="channel" multiple size="4">
+					for _, c := range channels {
+						<option value={ c } selected?={ f.HasChannel(c) }>{ c }</option>
+					}
+				</select>
+			</label>
+		}
 		<label class="filter-check">
 			<input type="checkbox" name="summarized" value="1" if f.OnlySummarized { checked }/>
 			Summarized only