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>

CLAUDE.md

@@ -85,7 +85,7 @@ Skills live in the canonical library `mathias/skills` and are wired into this re
 
 ## Current build state (start here for the first task)
 
-The repo is **green and shipping** — last tag `v0.8.0`. `task check` passes (fmt, vet, lint,
+The repo is **green and shipping** — last tag `v0.9.0`. `task check` passes (fmt, vet, lint,
 `go test -p 1 ./...`). Go is `1.26.1` (see `go.mod`).
 
 - Clean Architecture core is implemented: `internal/domain` (entities), `internal/ports`

cmd/tapir/discovery.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"context"
+	"log/slog"
+	"sync"
+
+	"gitea.d-ma.be/mathias/tapir/internal/runner"
+)
+
+// discoveryRunner runs one user's discovery pass.
+type discoveryRunner func(ctx context.Context, userID string) (runner.Stats, error)
+
+// serialize wraps run so calls never overlap: every discovery pass — scheduled
+// or connect-triggered (#6) — acquires the same lock, preserving the
+// one-fetcher-at-a-time invariant the scheduler relies on (ADR-018, the
+// single-replica assumption). Locking is per-user, so a connect-triggered pass
+// interleaves between the scheduler's users instead of waiting for a whole pass.
+func serialize(mu *sync.Mutex, run discoveryRunner) discoveryRunner {
+	return func(ctx context.Context, userID string) (runner.Stats, error) {
+		mu.Lock()
+		defer mu.Unlock()
+		return run(ctx, userID)
+	}
+}
+
+// discoveryTrigger fires an out-of-band discovery pass for one user without
+// blocking the caller (the connect HTTP handler). The pass runs on the server's
+// long-lived ctx — not the request ctx — so it survives the post-connect
+// redirect. run is the serialized runner, so a trigger never overlaps the
+// scheduler. Satisfies web.DiscoveryTrigger.
+type discoveryTrigger struct {
+	ctx context.Context
+	run discoveryRunner
+	// onboard, when set, runs after the discovery pass to summarize a capped number
+	// of the user's newest videos (Feature 1). Optional.
+	onboard func(ctx context.Context, userID string)
+	log     *slog.Logger
+}
+
+func (t *discoveryTrigger) Enqueue(userID string) {
+	go func() {
+		if _, err := t.run(t.ctx, userID); err != nil {
+			t.log.Warn("discovery: connect-triggered pass had errors", "user", userID, "err", err)
+		}
+		if t.onboard != nil {
+			t.onboard(t.ctx, userID)
+		}
+	}()
+}

cmd/tapir/discovery_test.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+
+	"gitea.d-ma.be/mathias/tapir/internal/runner"
+)
+
+// serialize must guarantee at most one discovery pass runs at a time, so a
+// connect-triggered pass never fetches concurrently with the scheduler.
+func TestSerializeRunsOneAtATime(t *testing.T) {
+	var active, maxActive int32
+	run := func(_ context.Context, _ string) (runner.Stats, error) {
+		n := atomic.AddInt32(&active, 1)
+		for { // record the high-water mark of concurrent runs
+			m := atomic.LoadInt32(&maxActive)
+			if n <= m || atomic.CompareAndSwapInt32(&maxActive, m, n) {
+				break
+			}
+		}
+		time.Sleep(2 * time.Millisecond)
+		atomic.AddInt32(&active, -1)
+		return runner.Stats{}, nil
+	}
+
+	s := serialize(&sync.Mutex{}, run)
+	var wg sync.WaitGroup
+	for i := 0; i < 20; i++ {
+		wg.Add(1)
+		go func(i int) { defer wg.Done(); _, _ = s(context.Background(), fmt.Sprintf("u%d", i)) }(i)
+	}
+	wg.Wait()
+
+	require.Equal(t, int32(1), atomic.LoadInt32(&maxActive),
+		"serialize must run at most one pass at a time")
+}
+
+// Enqueue runs the user's pass out-of-band (non-blocking) on the trigger's ctx.
+func TestDiscoveryTriggerEnqueueRunsUser(t *testing.T) {
+	done := make(chan string, 1)
+	run := func(_ context.Context, userID string) (runner.Stats, error) {
+		done <- userID
+		return runner.Stats{}, nil
+	}
+	tr := &discoveryTrigger{ctx: context.Background(), run: run, log: quietLog()}
+
+	tr.Enqueue("u1")
+
+	select {
+	case got := <-done:
+		require.Equal(t, "u1", got)
+	case <-time.After(2 * time.Second):
+		t.Fatal("Enqueue did not run the user's pass")
+	}
+}

cmd/tapir/main.go

@@ -20,6 +20,7 @@ import (
 	"net/http"
 	"os"
 	"os/signal"
+	"sync"
 	"time"
 
 	"gitea.d-ma.be/mathias/tapir/internal/adapters/secrets"
@@ -209,7 +210,10 @@ func cmdServe(ctx context.Context, log *slog.Logger) error {
 			ClientSecret: cfg.YTClientSecret,
 			RedirectURL:  cfg.YTConnectRedirectURL,
 		}, secretStore, st, log)
-		log.Info("web youtube connect enabled", "redirect", cfg.YTConnectRedirectURL)
+		// Paste-a-URL (Feature 2): same YouTube credentials, per-user adapter built
+		// per request. Mounting the /paste route keys off app.Fetcher being set.
+		app.Fetcher = videoFetcher{cfg: cfg, secrets: secretStore}
+		log.Info("web youtube connect + paste enabled", "redirect", cfg.YTConnectRedirectURL)
 	}
 
 	// Immediate summarization for the web "Summarize" button. When the engine can
@@ -238,13 +242,44 @@ func cmdServe(ctx context.Context, log *slog.Logger) error {
 	if cfg.DiscoveryInterval > 0 {
 		log.Info("scheduled discovery enabled", "interval", cfg.DiscoveryInterval, "fetch_rate", cfg.FetchRate)
 		log.Warn("scheduled discovery assumes a SINGLE replica — running serve at >1 replica double-runs discovery (ADR-018)")
-		runUser := func(ctx context.Context, userID string) (runner.Stats, error) {
+		rawRunUser := func(ctx context.Context, userID string) (runner.Stats, error) {
 			r, err := buildUserRunner(cfg, st, secretStore, userID, log)
 			if err != nil {
 				return runner.Stats{}, err
 			}
 			return r.RunOnce(ctx)
 		}
+		// One lock shared by the scheduler and connect-triggered passes (#6) so
+		// they never fetch concurrently — the single-fetcher invariant (ADR-018).
+		runUser := serialize(&sync.Mutex{}, rawRunUser)
+		// Onboarding burst (Feature 1): after the connect-triggered discovery pass,
+		// summarize up to OnboardSummarizeCount of the user's NEWEST unsummarized
+		// videos so a fresh account gets real summaries in its first session. Hard
+		// cap; explicit, so it bypasses the recency window — but every fetch still
+		// goes through globalFetchGate via the Processor. No-op when disabled
+		// (count 0) or queue-only (no Processor).
+		onboard := func(ctx context.Context, userID string) {
+			if cfg.OnboardSummarizeCount <= 0 || app.Processor == nil {
+				return
+			}
+			ids, err := st.NewestUnsummarizedVideoIDs(ctx, userID, cfg.OnboardSummarizeCount)
+			if err != nil {
+				log.Warn("onboarding: list newest unsummarized", "user", userID, "err", err)
+				return
+			}
+			for _, id := range ids {
+				if err := app.Processor.ProcessVideo(ctx, userID, id); err != nil {
+					log.Warn("onboarding: summarize", "user", userID, "video", id, "err", err)
+				}
+			}
+			if len(ids) > 0 {
+				log.Info("onboarding burst complete", "user", userID, "summarized", len(ids), "cap", cfg.OnboardSummarizeCount)
+			}
+		}
+		if app.Connect != nil {
+			app.Connect.Discovery = &discoveryTrigger{ctx: ctx, run: runUser, onboard: onboard, log: log}
+			log.Info("connect-triggered discovery enabled", "onboard_cap", cfg.OnboardSummarizeCount)
+		}
 		go runScheduler(ctx, cfg.DiscoveryInterval, st, runUser, log)
 	} else {
 		log.Info("scheduled discovery disabled (TAPIR_DISCOVERY_INTERVAL unset or 0)")

cmd/tapir/processor.go

@@ -11,9 +11,29 @@ import (
 	"gitea.d-ma.be/mathias/tapir/internal/adapters/youtube"
 	"gitea.d-ma.be/mathias/tapir/internal/config"
 	"gitea.d-ma.be/mathias/tapir/internal/domain"
+	"gitea.d-ma.be/mathias/tapir/internal/ports"
 	"gitea.d-ma.be/mathias/tapir/internal/usecase"
+	"gitea.d-ma.be/mathias/tapir/internal/web"
 )
 
+// videoFetcher adapts the YouTube adapter to web.VideoFetcher for the paste flow
+// (Feature 2). It builds a per-user adapter bound to that user's token ref and
+// resolves a single video's metadata via the Data API — ungated; only the later
+// transcript fetch goes through globalFetchGate.
+type videoFetcher struct {
+	cfg     config.Config
+	secrets ports.SecretStore
+}
+
+func (f videoFetcher) FetchVideo(ctx context.Context, userID, videoID string) (domain.Video, error) {
+	a := youtube.New(youtube.Config{
+		ClientID:       f.cfg.YTClientID,
+		ClientSecret:   f.cfg.YTClientSecret,
+		TokenSecretRef: web.YouTubeTokenRef(userID),
+	}, f.secrets)
+	return a.VideoByID(ctx, userID, videoID)
+}
+
 // buildProcessor wires the summarization engine — YouTube source (captions-first),
 // AI-router summarizer, store sink — shared by `tapir run` and the web
 // "Summarize now" path so the wiring lives in one place. It returns (nil, nil) —

docs/use-cases/connect_account.feature

@@ -18,6 +18,18 @@ Feature: Connect and manage video accounts
     Then the connection is stored with status "active"
     And my subscriptions are synced
 
+  Scenario: Connecting an account discovers videos immediately
+    Given I have no connected video accounts
+    When I connect my YouTube account
+    Then a discovery pass for my account is triggered right away
+    And I do not have to wait for the next scheduled pass to see my videos
+
+  Scenario: Connecting summarizes my newest videos right away
+    Given I have no connected video accounts
+    When I connect my YouTube account
+    Then up to the onboarding cap of my newest videos are summarized through the rate gate
+    And the rest are left to the scheduled recency-bounded pass
+
   Scenario: Tokens are never stored in the clear
     When I connect any video account
     Then no OAuth token value is stored in the database

docs/use-cases/paste_url.feature

@@ -0,0 +1,30 @@
+Feature: Paste a YouTube URL to summarize any video
+  As a user
+  I want to paste a YouTube link and get a summary
+  So that I can pull the specific video I want now, even from channels I don't follow
+
+  Scenario: Paste a valid YouTube URL
+    Given I am connected
+    When I paste a valid YouTube video URL
+    Then the video is added to my feed scoped to me
+    And it is queued for summarization through the shared rate gate
+
+  Scenario: Pasting an invalid link is rejected
+    When I paste something that is not a YouTube video URL
+    Then I get a clear error and nothing is added
+
+  Scenario: Pasting a video that cannot be found is honest
+    When I paste a URL whose video cannot be found
+    Then I am told it couldn't be found and nothing is added
+
+  Scenario: Pasting the same video twice does not duplicate it
+    Given I have pasted a video
+    When I paste the same video again
+    Then my feed still has exactly one entry for it
+
+  @pending
+  # Covered by the engine's ADR-010 no-transcript terminal state (degrade-never-error);
+  # there is no paste-specific test for it.
+  Scenario: A pasted video with no captions resolves honestly
+    When I paste a video that has no captions
+    Then it resolves to the "no transcript available" terminal state

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)
+			`INSERT INTO videos (user_id, provider, provider_video_id, title, url, published_at, channel_title)
-			 VALUES ($1, $2, $3, $4, $5, $6)
+			 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
+			     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)
 		}
@@ -72,3 +73,69 @@ func nullTime(t time.Time) *time.Time {
 	}
 	return &t
 }
+
+// NewestUnsummarizedVideoIDs returns up to limit of the user's videos that have
+// no summary yet, newest first (published_at DESC, NULLS LAST). It caps the
+// connect-time onboarding burst (Feature 1) at a fixed count: the caller marks
+// these for summarization through the shared rate gate. RLS-scoped via withUser,
+// so it only ever sees the requesting user's rows. limit <= 0 returns nil.
+func (s *Store) NewestUnsummarizedVideoIDs(ctx context.Context, userID string, limit int) ([]string, error) {
+	if limit <= 0 {
+		return nil, nil
+	}
+	var ids []string
+	if err := s.withUser(ctx, userID, func(tx pgx.Tx) error {
+		rows, err := tx.Query(ctx,
+			`SELECT v.id
+			   FROM videos v
+			  WHERE v.user_id = $1
+			    AND NOT EXISTS (
+			          SELECT 1 FROM summaries su
+			           WHERE su.user_id = v.user_id AND su.video_id = v.id)
+			  ORDER BY v.published_at DESC NULLS LAST, v.seen_at DESC
+			  LIMIT $2`, userID, limit)
+		if err != nil {
+			return fmt.Errorf("store: newest unsummarized: %w", err)
+		}
+		defer rows.Close()
+		for rows.Next() {
+			var id string
+			if err := rows.Scan(&id); err != nil {
+				return fmt.Errorf("store: scan newest unsummarized: %w", err)
+			}
+			ids = append(ids, id)
+		}
+		return rows.Err()
+	}); err != nil {
+		return nil, err
+	}
+	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

@@ -81,3 +81,61 @@ func TestUpsertVideo_PerUserIsolation(t *testing.T) {
 
 	require.NotEqual(t, idA, idB, "same provider video for two users must be two distinct rows")
 }
+
+func TestNewestUnsummarizedVideoIDs(t *testing.T) {
+	ctx := context.Background()
+	s := newStore(t)
+	resetDB(t, rawPool(t))
+
+	mk := func(user, pid string, day int) string {
+		v := ytVideo(user, pid, pid)
+		v.PublishedAt = time.Date(2026, 6, day, 12, 0, 0, 0, time.UTC)
+		id, err := s.UpsertVideo(ctx, v)
+		require.NoError(t, err)
+		return id
+	}
+
+	_ = mk(userA, "a1vid000001", 1)
+	id2 := mk(userA, "a2vid000002", 2)
+	id3 := mk(userA, "a3vid000003", 3)
+	id4 := mk(userA, "a4vid000004", 4)
+	mk(userB, "b1vid000009", 9) // userB's newest — must never leak via RLS
+
+	// The newest (v4) is summarized, so it's excluded from "unsummarized".
+	require.NoError(t, s.Deliver(ctx, summary(userA, id4, "done")))
+
+	// Cap 2, newest-first unsummarized: v3 then v2 (v4 excluded; userB excluded).
+	got, err := s.NewestUnsummarizedVideoIDs(ctx, userA, 2)
+	require.NoError(t, err)
+	require.Equal(t, []string{id3, id2}, got)
+
+	none, err := s.NewestUnsummarizedVideoIDs(ctx, userA, 0)
+	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

@@ -0,0 +1,62 @@
+package youtube
+
+import (
+	"context"
+	"errors"
+	"net/http"
+	"testing"
+
+	"gitea.d-ma.be/mathias/tapir/internal/domain"
+)
+
+func TestVideoByID(t *testing.T) {
+	const id = "dQw4w9WgXcQ"
+	a, secrets := newTestAdapter(t, func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path != "/videos" {
+			t.Errorf("unexpected path %q (must use videos.list)", r.URL.Path)
+		}
+		if got := r.URL.Query().Get("id"); got != id {
+			t.Errorf("expected id=%s, got %q", id, got)
+		}
+		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","channelTitle":"Rick Astley","publishedAt":"2026-05-20T09:00:00Z"}}]}`))
+	})
+
+	v, err := a.VideoByID(context.Background(), "u1", id)
+	if err != nil {
+		t.Fatalf("VideoByID: %v", err)
+	}
+	if v.UserID != "u1" {
+		t.Errorf("UserID = %q, want u1", v.UserID)
+	}
+	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)
+	}
+	if v.PublishedAt.IsZero() {
+		t.Errorf("expected publishedAt parsed, got zero")
+	}
+	if v.SubscriptionID != "" {
+		t.Errorf("a pasted video must have no subscription, got %q", v.SubscriptionID)
+	}
+	if secrets.byRef == nil {
+		t.Errorf("token must be resolved by reference through the SecretStore")
+	}
+}
+
+func TestVideoByIDNotFound(t *testing.T) {
+	a, _ := newTestAdapter(t, func(w http.ResponseWriter, _ *http.Request) {
+		_, _ = w.Write([]byte(`{"items":[]}`))
+	})
+	_, err := a.VideoByID(context.Background(), "u1", "missingvid0")
+	if !errors.Is(err, domain.ErrVideoNotFound) {
+		t.Fatalf("VideoByID for missing id = %v, want domain.ErrVideoNotFound", err)
+	}
+}

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,
 		})
@@ -244,6 +245,38 @@ func (a *Adapter) NewVideos(ctx context.Context, sub domain.Subscription) ([]dom
 	return videos, nil
 }
 
+// VideoByID fetches a single video's metadata (videos.list, snippet) for an
+// arbitrary video id — including channels the user does not follow (paste-a-URL,
+// Feature 2). This is a Data API call (1 quota unit), NOT the rate-limited
+// caption path, so it is not gated: only the later transcript fetch goes through
+// globalFetchGate. UserID is set on the result and SubscriptionID is left empty
+// (a pasted video has no subscription parent). Returns ErrVideoNotFound when the
+// id resolves to no video.
+func (a *Adapter) VideoByID(ctx context.Context, userID, videoID string) (domain.Video, error) {
+	client, err := a.httpClient(ctx, a.cfg.TokenSecretRef)
+	if err != nil {
+		return domain.Video{}, err
+	}
+	q := url.Values{"part": {"snippet"}, "id": {videoID}}
+	var resp videoListResponse
+	if err := a.getJSON(ctx, client, "/videos", q, &resp); err != nil {
+		return domain.Video{}, fmt.Errorf("video by id %q: %w", videoID, err)
+	}
+	if len(resp.Items) == 0 {
+		return domain.Video{}, fmt.Errorf("video %q: %w", videoID, domain.ErrVideoNotFound)
+	}
+	it := resp.Items[0]
+	return domain.Video{
+		UserID:          userID,
+		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
+}
+
 // uploadsPlaylistID derives a channel's uploads playlist id at zero API cost:
 // a standard channel id "UCxxxx" maps to uploads playlist "UUxxxx". Returns
 // ok=false for ids that don't follow this convention (caller falls back to
@@ -342,6 +375,16 @@ type playlistItemListResponse struct {
 	} `json:"items"`
 }
 
+type videoListResponse struct {
+	Items []struct {
+		Snippet struct {
+			Title        string    `json:"title"`
+			ChannelTitle string    `json:"channelTitle"`
+			PublishedAt  time.Time `json:"publishedAt"`
+		} `json:"snippet"`
+	} `json:"items"`
+}
+
 type channelListResponse struct {
 	Items []struct {
 		ContentDetails struct {

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)
 	}

internal/config/config.go

@@ -13,6 +13,7 @@ import (
 	"os"
 	"path/filepath"
 	"sort"
+	"strconv"
 	"strings"
 	"time"
 )
@@ -79,6 +80,13 @@ type Config struct {
 	// pre-recency behaviour). Default ~7 days.
 	AutoSummarizeWindow time.Duration
 
+	// OnboardSummarizeCount caps how many of a freshly-connected user's newest
+	// videos are summarized immediately on connect (the onboarding "it works"
+	// burst). HARD-capped at maxOnboardSummarizeCount so onboarding can never
+	// bulk-fetch; 0 disables the burst. Every fetch still flows through the shared
+	// caption rate gate (ADR-014) — the cap bounds count, never the pacing. Default 3.
+	OnboardSummarizeCount int
+
 	// DiscoveryInterval, when > 0, makes `serve` run in-process scheduled discovery
 	// for ALL users on that cadence (ADR-018). Zero/unset = disabled, so dev and
 	// tests never auto-fetch. Single-replica assumption — see cmdServe.
@@ -119,6 +127,8 @@ const (
 	defaultFetchRate             = 2 * time.Second
 	defaultPublicURL             = "https://tapir.d-ma.be"
 	defaultAutoSummarizeWindow   = 7 * 24 * time.Hour
+	defaultOnboardSummarizeCount = 3
+	maxOnboardSummarizeCount     = 5
 )
 
 // Load reads the environment into a Config, applying defaults. It does not
@@ -183,6 +193,18 @@ func Load() (Config, error) {
 	}
 	c.AutoSummarizeWindow = autoWindow
 
+	onboard, err := intOr("TAPIR_ONBOARD_SUMMARIZE_COUNT", defaultOnboardSummarizeCount)
+	if err != nil {
+		return Config{}, err
+	}
+	if onboard < 0 {
+		onboard = 0
+	}
+	if onboard > maxOnboardSummarizeCount {
+		onboard = maxOnboardSummarizeCount
+	}
+	c.OnboardSummarizeCount = onboard
+
 	return c, nil
 }
 
@@ -247,6 +269,18 @@ func envOr(key, fallback string) string {
 	return fallback
 }
 
+func intOr(key string, fallback int) (int, error) {
+	v := os.Getenv(key)
+	if v == "" {
+		return fallback, nil
+	}
+	n, err := strconv.Atoi(v)
+	if err != nil {
+		return 0, fmt.Errorf("config: %s=%q: %w", key, v, err)
+	}
+	return n, nil
+}
+
 func durationOr(key string, fallback time.Duration) (time.Duration, error) {
 	v := os.Getenv(key)
 	if v == "" {

internal/config/config_test.go

@@ -53,6 +53,38 @@ func TestLoad_AppliesDefaults(t *testing.T) {
 	}
 }
 
+func TestLoad_OnboardSummarizeCount(t *testing.T) {
+	cases := []struct {
+		name, env string
+		want      int
+	}{
+		{"default", "", defaultOnboardSummarizeCount},
+		{"explicit", "4", 4},
+		{"zero disables", "0", 0},
+		{"clamped to hard cap", "50", maxOnboardSummarizeCount},
+		{"negative clamps to zero", "-3", 0},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			setEnv(t, map[string]string{"TAPIR_ONBOARD_SUMMARIZE_COUNT": c.env})
+			cfg, err := Load()
+			if err != nil {
+				t.Fatalf("Load: %v", err)
+			}
+			if cfg.OnboardSummarizeCount != c.want {
+				t.Fatalf("OnboardSummarizeCount = %d, want %d", cfg.OnboardSummarizeCount, c.want)
+			}
+		})
+	}
+}
+
+func TestLoad_OnboardSummarizeCountInvalid(t *testing.T) {
+	setEnv(t, map[string]string{"TAPIR_ONBOARD_SUMMARIZE_COUNT": "three"})
+	if _, err := Load(); err == nil {
+		t.Fatal("Load: want error for non-numeric TAPIR_ONBOARD_SUMMARIZE_COUNT")
+	}
+}
+
 func TestLoad_ParsesValues(t *testing.T) {
 	setEnv(t, map[string]string{
 		"TAPIR_USER_ID":               "11111111-1111-1111-1111-111111111111",

internal/domain/domain.go

@@ -3,10 +3,16 @@
 package domain
 
 import (
+	"errors"
 	"fmt"
 	"time"
 )
 
+// ErrVideoNotFound is returned when a video id resolves to no video (deleted,
+// private, or a typo'd paste). Defined in domain so adapters and the web layer
+// share one sentinel without coupling to each other.
+var ErrVideoNotFound = errors.New("video not found")
+
 // ErrChannelUnavailable is returned by a VideoSource when a channel's upload
 // playlist returns HTTP 404 — the channel was deleted or made private. The runner
 // stores these so the account page can surface them to the user.
@@ -67,6 +73,7 @@ type Video struct {
 	Provider        Provider
 	ProviderVideoID string
 	Title           string
+	ChannelTitle    string
 	URL             string
 	PublishedAt     time.Time
 	SeenAt          time.Time

internal/web/connect.go

@@ -23,6 +23,15 @@ type Connections interface {
 	UpsertConnection(ctx context.Context, userID string, c store.Connection) error
 }
 
+// DiscoveryTrigger requests an out-of-band discovery pass for a user. The connect
+// flow fires it the moment a YouTube account is linked so videos appear promptly
+// instead of waiting for the next scheduled pass (#6). Enqueue must be
+// non-blocking and safe to call from the request goroutine; the implementation
+// owns serialization with the scheduler (one pass at a time). nil = no trigger.
+type DiscoveryTrigger interface {
+	Enqueue(userID string)
+}
+
 // connectStateTTL bounds how long a generated CSRF state is valid between the
 // connect redirect and the provider callback.
 const connectStateTTL = 10 * time.Minute
@@ -43,6 +52,10 @@ type ConnectHandler struct {
 	Conns   Connections
 	Log     *slog.Logger
 
+	// Discovery, when set, is fired after a successful connect so the new
+	// connection's videos are discovered immediately (#6). Optional.
+	Discovery DiscoveryTrigger
+
 	states *connectStateStore
 	now    func() time.Time
 }
@@ -134,6 +147,12 @@ func (h *ConnectHandler) handleCallback(w http.ResponseWriter, r *http.Request)
 		return
 	}
 
+	// Discover this user's videos now rather than waiting for the next scheduled
+	// pass (#6). Non-blocking; the trigger serializes with the scheduler.
+	if h.Discovery != nil {
+		h.Discovery.Enqueue(userID)
+	}
+
 	setFlash(w, flashConnected)
 	http.Redirect(w, r, "/", http.StatusSeeOther)
 }

internal/web/connect_test.go

@@ -45,6 +45,24 @@ func (c *fakeConns) UpsertConnection(_ context.Context, userID string, conn stor
 	return nil
 }
 
+// fakeTrigger records Enqueue calls so a test can assert connect fired discovery.
+type fakeTrigger struct {
+	mu    sync.Mutex
+	users []string
+}
+
+func (f *fakeTrigger) Enqueue(userID string) {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	f.users = append(f.users, userID)
+}
+
+func (f *fakeTrigger) seen() []string {
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	return append([]string(nil), f.users...)
+}
+
 // tokenServer fakes Google's token endpoint, returning body for any POST.
 func tokenServer(t *testing.T, body string) *httptest.Server {
 	t.Helper()
@@ -126,6 +144,36 @@ func TestCallbackExchangesAndRecordsConnection(t *testing.T) {
 	require.Equal(t, wantRef, conns.conn.TokenRef)
 }
 
+func TestCallbackTriggersDiscovery(t *testing.T) {
+	srv := tokenServer(t,
+		`{"access_token":"at","refresh_token":"rt-secret","token_type":"Bearer","expires_in":3600}`)
+	app := newConnectApp(t, srv.URL, &fakeWriter{}, &fakeConns{})
+	trig := &fakeTrigger{}
+	app.Connect.Discovery = trig
+
+	state := connectState(t, app)
+	rec := do(t, app, httptest.NewRequest(http.MethodGet,
+		"/oauth/youtube/callback?state="+state+"&code=the-code", nil))
+
+	require.Equal(t, http.StatusSeeOther, rec.Code)
+	require.Equal(t, []string{userID}, trig.seen(),
+		"a successful connect must trigger discovery for the connecting user")
+}
+
+func TestCallbackNoDiscoveryOnFailedConnect(t *testing.T) {
+	srv := tokenServer(t,
+		`{"access_token":"at","refresh_token":"rt","token_type":"Bearer","expires_in":3600}`)
+	app := newConnectApp(t, srv.URL, &fakeWriter{}, &fakeConns{})
+	trig := &fakeTrigger{}
+	app.Connect.Discovery = trig
+
+	// No state → CSRF reject → nothing connected, so no discovery.
+	rec := do(t, app, httptest.NewRequest(http.MethodGet,
+		"/oauth/youtube/callback?code=the-code", nil))
+	require.Equal(t, http.StatusBadRequest, rec.Code)
+	require.Empty(t, trig.seen(), "a failed connect must not trigger discovery")
+}
+
 func TestCallbackRejectsMissingState(t *testing.T) {
 	srv := tokenServer(t,
 		`{"access_token":"at","refresh_token":"rt","token_type":"Bearer","expires_in":3600}`)

internal/web/handlers.go

@@ -3,6 +3,8 @@ package web
 import (
 	"context"
 	"errors"
+	"html/template"
+	"io"
 	"log/slog"
 	"net/http"
 	"time"
@@ -10,6 +12,7 @@ import (
 	"github.com/a-h/templ"
 
 	"gitea.d-ma.be/mathias/tapir/internal/adapters/store"
+	"gitea.d-ma.be/mathias/tapir/internal/domain"
 )
 
 // Store is the read/write surface the web handlers depend on — a narrow port over
@@ -18,6 +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)
@@ -30,6 +36,10 @@ type Store interface {
 	SetAutoSummarize(ctx context.Context, userID string, enabled bool) error
 	RequestSummarize(ctx context.Context, userID, videoID string) error
 
+	// UpsertVideo persists a pasted video (idempotent on user+provider+video id,
+	// so it also dedups) and returns its durable store id.
+	UpsertVideo(ctx context.Context, v domain.Video) (string, error)
+
 	// Account management (the /account page, disconnect, delete-account).
 	ConnectionsForUser(ctx context.Context, userID string) ([]store.Connection, error)
 	DeleteConnection(ctx context.Context, userID, provider string) error
@@ -78,6 +88,9 @@ type App struct {
 	// background goroutine (the "Summarize" button kicks it off). Nil = queue-only:
 	// the button flips the DB flag and the next `tapir run` does the work.
 	Processor Processor
+	// Fetcher, when non-nil, resolves an arbitrary YouTube video id to metadata for
+	// the paste-a-URL flow (Feature 2). Nil = the /paste route is not mounted.
+	Fetcher VideoFetcher
 	// Processing tracks in-flight immediate summarizations so the status endpoint
 	// shows the animation until the summary lands. The zero value is ready to use.
 	Processing ProcessingSet
@@ -132,6 +145,9 @@ func (a *App) Router() http.Handler {
 	app.HandleFunc("POST /v/{videoId}/action", a.handleAction)
 	app.HandleFunc("POST /v/{videoId}/summarize", a.handleRequestSummarize)
 	app.HandleFunc("POST /v/{videoId}/retry-now", a.handleRetryNow)
+	if a.Fetcher != nil {
+		app.HandleFunc("POST /paste", a.handlePaste)
+	}
 	app.HandleFunc("GET /v/{videoId}/status", a.handleStatus)
 	app.HandleFunc("GET /register", a.handleRegisterForm)
 	app.HandleFunc("POST /register", a.handleRegister)
@@ -183,7 +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",
@@ -198,25 +214,30 @@ func (a *App) handleList(w http.ResponseWriter, r *http.Request) {
 	rows := f.apply(allRows)
 	buckets := bucketRows(rows, a.recencyCutoff())
 
-	// hasConnected drives the empty state: a fresh account with a connection but
+	// Channel options for the multi-select filter (the user's source channels).
-	// no discovery pass yet has zero rows, and we want it to read "connected,
+	channels, err := a.Store.DistinctChannels(r.Context(), userID)
-	// summaries land gradually" rather than "nothing here". Only needed when the
+	if err != nil {
-	// list is empty.
+		a.serverError(w, r, "distinct channels", err)
-	hasConnected := false
+		return
-	if buckets.empty() {
+	}
+
+	// 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").
+	// Computed every render — not only when empty — so a user with videos still
+	// gets the paste box.
 	conns, err := a.Store.ConnectionsForUser(r.Context(), userID)
 	if err != nil {
 		a.serverError(w, r, "connections for user", err)
 		return
 	}
-		hasConnected = len(conns) > 0
+	hasConnected := len(conns) > 0
-	}
 
 	if isHTMX(r) {
 		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).
@@ -324,6 +345,75 @@ func (a *App) handleRequestSummarize(w http.ResponseWriter, r *http.Request) {
 	a.render(w, r, VideoCard(*row))
 }
 
+// handlePaste handles "paste a YouTube URL" (Feature 2). It parses the video id,
+// fetches metadata (Data API — ungated), upserts a subscription-less video row
+// scoped to the user (idempotent, so it also dedups), and — if the video isn't
+// already summarized — requests a summary and kicks off immediate processing
+// through the SAME rate gate as the Summarize button. An explicit paste is a
+// manual request, so it summarizes regardless of the recency window. A video that
+// turns out to have no captions resolves to the honest "no transcript" terminal
+// state via the engine (ADR-010), not an error here.
+func (a *App) handlePaste(w http.ResponseWriter, r *http.Request) {
+	userID, ok := a.currentUserID(w, r)
+	if !ok {
+		return
+	}
+	videoID, err := parseYouTubeVideoID(r.FormValue("url"))
+	if err != nil {
+		a.pasteFailure(w, http.StatusBadRequest, "That doesn't look like a YouTube video link.")
+		return
+	}
+
+	v, err := a.Fetcher.FetchVideo(r.Context(), userID, videoID)
+	if errors.Is(err, domain.ErrVideoNotFound) {
+		a.pasteFailure(w, http.StatusNotFound, "That video couldn't be found — it may be private or removed.")
+		return
+	}
+	if err != nil {
+		a.serverError(w, r, "paste fetch", err)
+		return
+	}
+
+	id, err := a.Store.UpsertVideo(r.Context(), v)
+	if err != nil {
+		a.serverError(w, r, "paste upsert", err)
+		return
+	}
+	row, err := a.Store.GetVideoRow(r.Context(), userID, id)
+	if err != nil {
+		a.serverError(w, r, "paste get video", err)
+		return
+	}
+
+	// Dedup: already in the feed with a summary — surface the existing entry,
+	// don't re-summarize.
+	if row.Summarized {
+		a.render(w, r, VideoCard(*row))
+		return
+	}
+
+	// New or unsummarized: queue + (if a Processor is wired) summarize now, through
+	// the shared gate. RequestSummarize makes it durable even if the process dies.
+	if err := a.Store.RequestSummarize(r.Context(), userID, id); err != nil {
+		a.serverError(w, r, "paste request summarize", err)
+		return
+	}
+	if a.Processor != nil {
+		a.startProcessing(userID, id)
+		a.render(w, r, processingCard(*row))
+		return
+	}
+	a.render(w, r, VideoCard(*row))
+}
+
+// pasteFailure renders a minimal inline error fragment for the paste form (HTMX
+// swaps it in). No templ dependency so it renders even on a bad-input fast path.
+func (a *App) pasteFailure(w http.ResponseWriter, status int, msg string) {
+	w.Header().Set("Content-Type", "text/html; charset=utf-8")
+	w.WriteHeader(status)
+	_, _ = io.WriteString(w, `<p class="paste-error" role="alert">`+template.HTMLEscapeString(msg)+`</p>`)
+}
+
 // handleRetryNow handles the "Try now" button on rate-limited video cards. It
 // clears the rate_limited_at backoff so the scheduler won't skip the video, then
 // triggers an immediate ProcessVideo — same background path as handleRequestSummarize.

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.
+	// Selecting a different channel hides the row; selecting its channel shows it.
-	rec := do(t, app, httptest.NewRequest(http.MethodGet, "/?channel=vimeo", nil))
+	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.go

@@ -0,0 +1,62 @@
+package web
+
+import (
+	"fmt"
+	"net/url"
+	"regexp"
+	"strings"
+)
+
+// youtubeVideoID matches a canonical YouTube video id: exactly 11 URL-safe chars.
+var youtubeVideoID = regexp.MustCompile(`^[A-Za-z0-9_-]{11}$`)
+
+// parseYouTubeVideoID extracts the 11-character video id from a pasted YouTube
+// URL (watch?v=, youtu.be/, shorts/, embed/) or a bare id. It rejects non-YouTube
+// hosts and anything that doesn't yield a valid id, so the paste flow never tries
+// to fetch a video that can't exist (Feature 2).
+func parseYouTubeVideoID(raw string) (string, error) {
+	s := strings.TrimSpace(raw)
+	if s == "" {
+		return "", fmt.Errorf("empty input")
+	}
+
+	// Bare id (no URL) — accept directly.
+	if youtubeVideoID.MatchString(s) {
+		return s, nil
+	}
+
+	// Accept scheme-less URLs (youtube.com/watch?v=...) by giving url.Parse a host.
+	if !strings.Contains(s, "://") {
+		s = "https://" + s
+	}
+	u, err := url.Parse(s)
+	if err != nil {
+		return "", fmt.Errorf("not a URL: %w", err)
+	}
+
+	host := strings.ToLower(u.Hostname())
+	isYouTube := host == "youtu.be" || host == "youtube.com" || strings.HasSuffix(host, ".youtube.com")
+	if !isYouTube {
+		return "", fmt.Errorf("not a YouTube URL: %q", host)
+	}
+
+	var id string
+	switch {
+	case host == "youtu.be":
+		// youtu.be/<id>
+		id = strings.Trim(u.Path, "/")
+	case u.Path == "/watch":
+		id = u.Query().Get("v")
+	default:
+		// /shorts/<id>, /embed/<id>
+		parts := strings.Split(strings.Trim(u.Path, "/"), "/")
+		if len(parts) == 2 && (parts[0] == "shorts" || parts[0] == "embed") {
+			id = parts[1]
+		}
+	}
+
+	if !youtubeVideoID.MatchString(id) {
+		return "", fmt.Errorf("no YouTube video id in %q", raw)
+	}
+	return id, nil
+}

internal/web/paste_handler_test.go

@@ -0,0 +1,134 @@
+package web_test
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+
+	"gitea.d-ma.be/mathias/tapir/internal/domain"
+)
+
+// fakeFetcher is a web.VideoFetcher returning a fixed video (or an error),
+// scoped to whatever (userID, videoID) the handler asks for.
+type fakeFetcher struct {
+	title string
+	err   error
+	calls int
+}
+
+func (f *fakeFetcher) FetchVideo(_ context.Context, userID, videoID string) (domain.Video, error) {
+	f.calls++
+	if f.err != nil {
+		return domain.Video{}, f.err
+	}
+	return domain.Video{
+		UserID:          userID,
+		Provider:        domain.ProviderYouTube,
+		ProviderVideoID: videoID,
+		Title:           f.title,
+		URL:             "https://www.youtube.com/watch?v=" + videoID,
+	}, nil
+}
+
+func pasteReq(rawURL string) *http.Request {
+	req := httptest.NewRequest(http.MethodPost, "/paste",
+		strings.NewReader("url="+url.QueryEscape(rawURL)))
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	return req
+}
+
+func TestPasteValidURLAddsAndRequests(t *testing.T) {
+	ctx := context.Background()
+	app := newApp(t)
+	resetDB(t, rawPool(t))
+	app.Fetcher = &fakeFetcher{title: "Pasted Talk"}
+	p := rawPool(t)
+
+	rec := do(t, app, pasteReq("https://youtu.be/dQw4w9WgXcQ"))
+	require.Equal(t, http.StatusOK, rec.Code)
+
+	var (
+		count, requested int
+		title            string
+	)
+	require.NoError(t, p.QueryRow(ctx,
+		`SELECT count(*), coalesce(max(title),'') FROM videos
+		  WHERE user_id=$1 AND provider_video_id='dQw4w9WgXcQ'`, userID).Scan(&count, &title))
+	require.Equal(t, 1, count, "pasted video added once, scoped to the user")
+	require.Equal(t, "Pasted Talk", title)
+
+	require.NoError(t, p.QueryRow(ctx,
+		`SELECT count(*) FROM videos
+		  WHERE user_id=$1 AND provider_video_id='dQw4w9WgXcQ' AND summarize_requested`,
+		userID).Scan(&requested))
+	require.Equal(t, 1, requested, "pasted video is queued for summarization (through the gate)")
+}
+
+func TestPasteInvalidURLRejected(t *testing.T) {
+	app := newApp(t)
+	resetDB(t, rawPool(t))
+	app.Fetcher = &fakeFetcher{title: "x"}
+
+	rec := do(t, app, pasteReq("definitely not a url"))
+	require.Equal(t, http.StatusBadRequest, rec.Code)
+
+	var count int
+	require.NoError(t, rawPool(t).QueryRow(context.Background(),
+		`SELECT count(*) FROM videos WHERE user_id=$1`, userID).Scan(&count))
+	require.Equal(t, 0, count, "invalid input adds nothing")
+}
+
+func TestPasteVideoNotFound(t *testing.T) {
+	app := newApp(t)
+	resetDB(t, rawPool(t))
+	app.Fetcher = &fakeFetcher{err: domain.ErrVideoNotFound}
+
+	rec := do(t, app, pasteReq("https://youtu.be/dQw4w9WgXcQ"))
+	require.Equal(t, http.StatusNotFound, rec.Code)
+
+	var count int
+	require.NoError(t, rawPool(t).QueryRow(context.Background(),
+		`SELECT count(*) FROM videos WHERE user_id=$1`, userID).Scan(&count))
+	require.Equal(t, 0, count, "a not-found video adds nothing")
+}
+
+func TestPasteDedupNoDuplicate(t *testing.T) {
+	app := newApp(t)
+	resetDB(t, rawPool(t))
+	app.Fetcher = &fakeFetcher{title: "Pasted Talk"}
+
+	require.Equal(t, http.StatusOK, do(t, app, pasteReq("https://youtu.be/dQw4w9WgXcQ")).Code)
+	require.Equal(t, http.StatusOK, do(t, app, pasteReq("https://www.youtube.com/watch?v=dQw4w9WgXcQ")).Code)
+
+	var count int
+	require.NoError(t, rawPool(t).QueryRow(context.Background(),
+		`SELECT count(*) FROM videos WHERE user_id=$1 AND provider_video_id='dQw4w9WgXcQ'`,
+		userID).Scan(&count))
+	require.Equal(t, 1, count, "pasting the same video twice must not duplicate the row")
+}
+
+func TestListShowsPasteFormForConnectedUserWithVideos(t *testing.T) {
+	app := newApp(t)
+	resetDB(t, rawPool(t))
+	app.Fetcher = &fakeFetcher{title: "x"}
+	p := rawPool(t)
+
+	// Connected user with a non-empty feed (the case the bug missed: hasConnected
+	// was only computed for an empty feed).
+	_, err := p.Exec(context.Background(),
+		`INSERT INTO video_connections (user_id, provider, token_ref, status)
+		 VALUES ($1, 'youtube', 'youtube/x/refresh_token', 'active')`, userID)
+	require.NoError(t, err)
+	seedVideo(t, p, "11111111-1111-1111-1111-111111111111", "A talk", "https://youtu.be/aaaaaaaaaaa", time.Now())
+
+	rec := do(t, app, httptest.NewRequest(http.MethodGet, "/", nil))
+	require.Equal(t, http.StatusOK, rec.Code)
+	require.Contains(t, body(t, rec), `action="/paste"`,
+		"a connected user must see the paste box even when the feed has videos")
+}

internal/web/paste_test.go

@@ -0,0 +1,97 @@
+package web
+
+import (
+	"bytes"
+	"context"
+	"gitea.d-ma.be/mathias/tapir/internal/adapters/store"
+	"strings"
+	"testing"
+)
+
+func TestParseYouTubeVideoID(t *testing.T) {
+	const id = "dQw4w9WgXcQ"
+	ok := []struct {
+		name, in string
+	}{
+		{"watch", "https://www.youtube.com/watch?v=" + id},
+		{"watch no www", "https://youtube.com/watch?v=" + id},
+		{"watch m", "https://m.youtube.com/watch?v=" + id},
+		{"watch extra params", "https://www.youtube.com/watch?v=" + id + "&t=42s&list=PLxyz"},
+		{"watch param after", "https://www.youtube.com/watch?list=PLxyz&v=" + id},
+		{"short link", "https://youtu.be/" + id},
+		{"short link param", "https://youtu.be/" + id + "?si=abcd&t=1"},
+		{"shorts", "https://www.youtube.com/shorts/" + id},
+		{"embed", "https://www.youtube.com/embed/" + id},
+		{"bare id", id},
+		{"http scheme", "http://youtube.com/watch?v=" + id},
+		{"no scheme", "youtube.com/watch?v=" + id},
+		{"trailing space", "  https://youtu.be/" + id + "  "},
+	}
+	for _, c := range ok {
+		t.Run(c.name, func(t *testing.T) {
+			got, err := parseYouTubeVideoID(c.in)
+			if err != nil {
+				t.Fatalf("parseYouTubeVideoID(%q) error: %v", c.in, err)
+			}
+			if got != id {
+				t.Fatalf("parseYouTubeVideoID(%q) = %q, want %q", c.in, got, id)
+			}
+		})
+	}
+
+	bad := []struct {
+		name, in string
+	}{
+		{"empty", ""},
+		{"blank", "   "},
+		{"vimeo", "https://vimeo.com/123456789"},
+		{"other host", "https://example.com/watch?v=" + id},
+		{"watch no id", "https://www.youtube.com/watch?v="},
+		{"short id", "https://youtu.be/abc"},
+		{"long id", "https://youtu.be/" + id + "extra"},
+		{"bad chars", "https://youtu.be/dQw4w9Wg!cQ"},
+		{"not a url", "just some text"},
+		{"channel url", "https://www.youtube.com/@somechannel"},
+	}
+	for _, c := range bad {
+		t.Run("reject "+c.name, func(t *testing.T) {
+			if got, err := parseYouTubeVideoID(c.in); err == nil {
+				t.Fatalf("parseYouTubeVideoID(%q) = %q, want error", c.in, got)
+			}
+		})
+	}
+}
+
+func TestListPageShowsPasteFormOnlyWhenConnected(t *testing.T) {
+	render := func(connected bool) string {
+		var buf bytes.Buffer
+		if err := ListPage(listBuckets{}, Filter{}, PipelineStats{}, "", connected, nil).Render(context.Background(), &buf); err != nil {
+			t.Fatalf("render: %v", err)
+		}
+		return buf.String()
+	}
+
+	html := render(true)
+	if !strings.Contains(html, `name="url"`) || !strings.Contains(html, `action="/paste"`) {
+		t.Errorf("connected feed must show the paste form")
+	}
+	if strings.Contains(render(false), `name="url"`) {
+		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/processing.go

@@ -3,6 +3,8 @@ package web
 import (
 	"context"
 	"sync"
+
+	"gitea.d-ma.be/mathias/tapir/internal/domain"
 )
 
 // Processor runs the core summarization use case for a single already-discovered
@@ -14,6 +16,14 @@ type Processor interface {
 	ProcessVideo(ctx context.Context, userID, videoID string) error
 }
 
+// VideoFetcher resolves an arbitrary YouTube video id to its metadata for the
+// paste-a-URL flow (Feature 2). It is a Data API call, NOT the rate-limited
+// caption path. Returns domain.ErrVideoNotFound for a deleted/private/typo'd id.
+// cmd/tapir wires a per-user YouTube adapter; nil disables the paste route.
+type VideoFetcher interface {
+	FetchVideo(ctx context.Context, userID, videoID string) (domain.Video, error)
+}
+
 // ProcessingSet tracks the (user, video) ids currently being summarized in-process
 // so the status endpoint can show the animation until the summary lands. It is
 // ephemeral (single-instance Stage-1): a restart drops it, and the DB holds the

internal/web/view.go

@@ -2,6 +2,7 @@ package web
 
 import (
 	"regexp"
+	"slices"
 	"strings"
 	"time"
 	"unicode/utf8"
@@ -333,7 +334,7 @@ type flashView struct {
 // flashMessages maps each flash code to its banner. An unknown code renders no
 // banner (flashFor returns ok=false), so a forged cookie value is inert.
 var flashMessages = map[string]flashView{
-	flashConnected:     {"success", "YouTube account connected."},
+	flashConnected:     {"success", "YouTube account connected — finding your subscriptions. Your newest videos will appear below as they're summarized."},
 	flashConnectFailed: {"error", "Could not connect your YouTube account. Please try again."},
 	flashDisconnected:  {"success", "Account disconnected."},
 	flashDeleted:       {"success", "Your account and all its data were deleted."},
@@ -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

@@ -104,11 +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)
@@ -143,7 +146,29 @@ templ pipelineBar(s PipelineStats) {
 	</div>
 }
 
-templ filterForm(f Filter) {
+// pasteForm lets a connected user summarize any YouTube video by pasting its URL
+// (Feature 2). The result (a video card, or an inline error) swaps into
+// #paste-result; the next list refresh shows it inline. Summarization runs
+// through the shared caption rate gate like every other fetch.
+templ pasteForm() {
+	<form
+		class="paste"
+		method="post"
+		action="/paste"
+		hx-post="/paste"
+		hx-target="#paste-result"
+		hx-swap="innerHTML"
+	>
+		<label>
+			Summarize any video
+			<input type="url" name="url" placeholder="Paste a YouTube link…" required/>
+		</label>
+		<button type="submit">Add</button>
+	</form>
+	<div id="paste-result"></div>
+}
+
+templ filterForm(f Filter, channels []string) {
 	<form
 		class="filters"
 		method="get"
@@ -153,7 +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

test/acceptance/scenario_coverage_test.go

@@ -38,7 +38,15 @@ var scenarioCoverage = map[string]string{
 
 	// connect_account.feature
 	"Connect a YouTube account":                          "TestCallbackExchangesAndRecordsConnection",
+	"Connecting an account discovers videos immediately": "TestCallbackTriggersDiscovery",
+	"Connecting summarizes my newest videos right away":  "TestNewestUnsummarizedVideoIDs",
 	"Tokens are never stored in the clear":               "TestCallbackExchangesAndRecordsConnection",
+
+	// paste_url.feature
+	"Paste a valid YouTube URL":                              "TestPasteValidURLAddsAndRequests",
+	"Pasting an invalid link is rejected":                    "TestPasteInvalidURLRejected",
+	"Pasting a video that cannot be found is honest":         "TestPasteVideoNotFound",
+	"Pasting the same video twice does not duplicate it":     "TestPasteDedupNoDuplicate",
 	"Revoking a connection stops watching but keeps history": "TestDisconnectRemovesTokenAndConnectionKeepsAccount",
 
 	// summarize_mode.feature