feat(onboard): burst picks likely-good videos, summarizes with stronger model (ADR-028)

Wire the onboarding burst to its quality-aware selection and a stronger model:
- main.go onboard uses OnboardBurstVideoIDs (junk-avoiding) instead of pure
  newest-first, bounded by MinVideoSeconds / OnboardMaxVideoSeconds.
- buildBurstProcessor builds a burst-only summarizer chain led by the onboard
  model (burstChainModels: onboard -> standard ADR-022 chain, deduped, NDA lever
  intact), over the same store/cache/sink. Collapses onto the shared Processor
  when the onboard model is empty/equal-to-primary or config is incomplete.
- summarizerEndpoint + newYouTubeSource extracted so standard and burst wiring
  share one definition.
- Remove now-superseded NewestUnsummarizedVideoIDs: OnboardBurstVideoIDs(.,0,0)
  is identical pure-newest behaviour and its test covers RLS + ordering.

cmd/tapir/main.go

@@ -262,23 +262,36 @@ func cmdServe(ctx context.Context, log *slog.Logger) error {
 		// 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).
+		// Onboarding burst (Feature 1, refined by ADR-028): after the connect-triggered
+		// discovery pass, summarize up to OnboardSummarizeCount of the user's newest
+		// LIKELY-GOOD unsummarized videos so a fresh account gets a strong first
+		// session. Selection avoids known-junk (Shorts/over-long/livestream VODs via
+		// the persisted duration); the burst leads its chain with the stronger onboard
+		// model. Hard cap; explicit, so it bypasses the recency window — but every
+		// fetch still goes through globalFetchGate. No-op when disabled (count 0) or
+		// queue-only (no processor).
+		//
+		// burstProcessor leads with the stronger model (ADR-028); it collapses onto the
+		// shared Processor when the onboard model is empty/equal-to-primary or the
+		// engine config is incomplete.
+		burstProcessor := app.Processor
+		if burstEngine, berr := buildBurstProcessor(cfg, st); berr != nil {
+			return berr
+		} else if burstEngine != nil {
+			burstProcessor = &engineProcessor{engine: burstEngine, store: st}
+			log.Info("onboarding burst uses a stronger model", "onboard_model", cfg.OnboardSummarizerModel)
+		}
 		onboard := func(ctx context.Context, userID string) {
-			if cfg.OnboardSummarizeCount <= 0 || app.Processor == nil {
+			if cfg.OnboardSummarizeCount <= 0 || burstProcessor == nil {
 				return
 			}
-			ids, err := st.NewestUnsummarizedVideoIDs(ctx, userID, cfg.OnboardSummarizeCount)
+			ids, err := st.OnboardBurstVideoIDs(ctx, userID, cfg.OnboardSummarizeCount, cfg.MinVideoSeconds, cfg.OnboardMaxVideoSeconds)
 			if err != nil {
-				log.Warn("onboarding: list newest unsummarized", "user", userID, "err", err)
+				log.Warn("onboarding: list burst candidates", "user", userID, "err", err)
 				return
 			}
 			for _, id := range ids {
-				if err := app.Processor.ProcessVideo(ctx, userID, id); err != nil {
+				if err := burstProcessor.ProcessVideo(ctx, userID, id); err != nil {
 					log.Warn("onboarding: summarize", "user", userID, "video", id, "err", err)
 				}
 			}

cmd/tapir/processor.go

@@ -52,13 +52,7 @@ func (f videoFetcher) FetchVideo(ctx context.Context, userID, videoID string) (d
 // alias, not a second client config. Empty model entries are skipped, so a
 // client deployment can set the cloud fallback empty to keep content local.
 func buildSummarizer(cfg config.Config) *summarizer.Summarizer {
-	mk := func(model string) summarizer.Endpoint {
-		return summarizer.Endpoint{
-			Client:   llm.New(cfg.GatewayURL, cfg.GatewayKey, model, cfg.SummarizerTimeout, llm.WithMaxTokens(cfg.SummaryMaxTokens)),
-			Provider: providerOf(model),
-			Model:    model,
-		}
-	}
+	mk := summarizerEndpoint(cfg)
 	eps := []summarizer.Endpoint{mk(cfg.SummarizerModel)}
 	if cfg.FallbackModel != "" && cfg.FallbackModel != cfg.SummarizerModel {
 		eps = append(eps, mk(cfg.FallbackModel))
@@ -69,6 +63,55 @@ func buildSummarizer(cfg config.Config) *summarizer.Summarizer {
 	return summarizer.NewChain(eps, cfg.MaxTranscriptChars)
 }
 
+// summarizerEndpoint returns a constructor for a chain endpoint over the one
+// LiteLLM gateway, varying only the model alias (the gateway fronts both
+// llama-swap and berget). Shared by the standard and burst chains.
+func summarizerEndpoint(cfg config.Config) func(model string) summarizer.Endpoint {
+	return func(model string) summarizer.Endpoint {
+		return summarizer.Endpoint{
+			Client:   llm.New(cfg.GatewayURL, cfg.GatewayKey, model, cfg.SummarizerTimeout, llm.WithMaxTokens(cfg.SummaryMaxTokens)),
+			Provider: providerOf(model),
+			Model:    model,
+		}
+	}
+}
+
+// burstChainModels is the ordered, deduped model list for the onboarding burst
+// (ADR-028): the stronger onboard model leads, then the standard ADR-022 chain
+// (primary → local fallback → cloud) follows as resilience. Empty entries are
+// dropped and duplicates collapsed, so the NDA lever (empty cloud fallback) keeps
+// the burst chain fully local exactly as the standard chain does.
+func burstChainModels(cfg config.Config) []string {
+	var models []string
+	add := func(m string) {
+		if m == "" {
+			return
+		}
+		for _, e := range models {
+			if e == m {
+				return
+			}
+		}
+		models = append(models, m)
+	}
+	add(cfg.OnboardSummarizerModel)
+	add(cfg.SummarizerModel)
+	add(cfg.FallbackModel)
+	add(cfg.CloudFallbackModel)
+	return models
+}
+
+// buildBurstSummarizer builds the onboarding-burst summarizer chain (ADR-028):
+// the onboard model first, then the standard chain as fallback, deduped.
+func buildBurstSummarizer(cfg config.Config) *summarizer.Summarizer {
+	mk := summarizerEndpoint(cfg)
+	var eps []summarizer.Endpoint
+	for _, m := range burstChainModels(cfg) {
+		eps = append(eps, mk(m))
+	}
+	return summarizer.NewChain(eps, cfg.MaxTranscriptChars)
+}
+
 // chatModels is the ordered, local-first set of models offered in the chat
 // switcher (ADR-027), reusing the ADR-022 chain: primary → local fallback →
 // cloud. Empty entries are dropped and duplicates collapsed, so a client/NDA
@@ -126,15 +169,7 @@ func buildProcessor(cfg config.Config, st *store.Store) (*usecase.Engine, error)
 		return nil, nil
 	}
 
-	secretStore := secrets.NewFileStore(cfg.SecretsFile)
-	src := youtube.New(youtube.Config{
-		ClientID:           cfg.YTClientID,
-		ClientSecret:       cfg.YTClientSecret,
-		TokenSecretRef:     cfg.YTTokenRef,
-		PreferredLanguages: []string{"en"},
-		MinVideoSeconds:    cfg.MinVideoSeconds,
-	}, secretStore)
-
+	src := newYouTubeSource(cfg, secrets.NewFileStore(cfg.SecretsFile))
 	sum := buildSummarizer(cfg)
 
 	// The store is both the summary sink and the shared transcript cache (ADR-021):
@@ -145,6 +180,38 @@ func buildProcessor(cfg config.Config, st *store.Store) (*usecase.Engine, error)
 	return eng, nil
 }
 
+// newYouTubeSource builds the captions-first VideoSource shared by the standard
+// and burst processors — same per-process YouTube credentials and ADR-023 Shorts
+// filter; only the summarizer chain differs between them.
+func newYouTubeSource(cfg config.Config, secretStore ports.SecretStore) ports.VideoSource {
+	return youtube.New(youtube.Config{
+		ClientID:           cfg.YTClientID,
+		ClientSecret:       cfg.YTClientSecret,
+		TokenSecretRef:     cfg.YTTokenRef,
+		PreferredLanguages: []string{"en"},
+		MinVideoSeconds:    cfg.MinVideoSeconds,
+	}, secretStore)
+}
+
+// buildBurstProcessor wires a processor whose summarizer leads with the stronger
+// onboard model (ADR-028), used only by the connect-time burst over the SAME
+// store / transcript cache / sink — a wiring choice; the engine and ports are
+// unchanged. Returns (nil, nil) — the collapse lever — when the onboard model is
+// empty or equal to the primary (the burst then reuses the shared processor), or
+// when the engine config is incomplete (queue-only, same as buildProcessor).
+func buildBurstProcessor(cfg config.Config, st *store.Store) (*usecase.Engine, error) {
+	if cfg.OnboardSummarizerModel == "" || cfg.OnboardSummarizerModel == cfg.SummarizerModel {
+		return nil, nil
+	}
+	if cfg.GatewayURL == "" || cfg.YTClientID == "" || cfg.YTClientSecret == "" || cfg.SecretsFile == "" {
+		return nil, nil
+	}
+	src := newYouTubeSource(cfg, secrets.NewFileStore(cfg.SecretsFile))
+	eng := usecase.NewEngine(src, buildBurstSummarizer(cfg), st)
+	eng.Transcripts = st
+	return eng, nil
+}
+
 // engineProcessor adapts the engine (which works in terms of a domain.Video) to
 // the web.Processor port (which works in terms of a stored video id): it loads the
 // video row, runs the engine, and — on a produced summary — clears the manual

cmd/tapir/processor_test.go

@@ -45,3 +45,65 @@ func TestBuildProcessorNilOnIncompleteConfig(t *testing.T) {
 		})
 	}
 }
+
+// TestBurstChainModelsLeadsWithOnboardModel: the onboarding burst chain (ADR-028)
+// leads with the stronger onboard model, then falls back through the standard
+// ADR-022 chain (primary -> local fallback -> cloud), deduped.
+func TestBurstChainModelsLeadsWithOnboardModel(t *testing.T) {
+	got := burstChainModels(config.Config{
+		OnboardSummarizerModel: "iguana/gemma4-26b",
+		SummarizerModel:        "koala/phi4-mini",
+		FallbackModel:          "iguana/gemma4-26b", // also the onboard model -> dedup
+		CloudFallbackModel:     "berget/mistral-small",
+	})
+	want := []string{"iguana/gemma4-26b", "koala/phi4-mini", "berget/mistral-small"}
+	if len(got) != len(want) {
+		t.Fatalf("burstChainModels = %v, want %v", got, want)
+	}
+	for i := range want {
+		if got[i] != want[i] {
+			t.Fatalf("burstChainModels = %v, want %v", got, want)
+		}
+	}
+}
+
+// TestBurstChainModelsCloudAbsentWhenDisabled: the NDA lever holds for the burst
+// too — empty cloud fallback keeps the burst chain fully local.
+func TestBurstChainModelsCloudAbsentWhenDisabled(t *testing.T) {
+	got := burstChainModels(config.Config{
+		OnboardSummarizerModel: "iguana/gemma4-26b",
+		SummarizerModel:        "koala/phi4-mini",
+		CloudFallbackModel:     "",
+	})
+	for _, m := range got {
+		if m == "" || m == "berget/mistral-small" {
+			t.Fatalf("cloud model leaked into burst chain: %v", got)
+		}
+	}
+}
+
+// TestBuildBurstProcessorNilWhenCollapsed: an empty or primary-equal onboard model
+// collapses the burst onto the shared processor (buildBurstProcessor returns nil).
+func TestBuildBurstProcessorNilWhenCollapsed(t *testing.T) {
+	base := config.Config{
+		GatewayURL:      "http://gw/v1",
+		YTClientID:      "id",
+		YTClientSecret:  "secret",
+		SecretsFile:     "/tmp/secrets.json",
+		SummarizerModel: "koala/phi4-mini",
+	}
+	t.Run("empty onboard model", func(t *testing.T) {
+		base.OnboardSummarizerModel = ""
+		eng, err := buildBurstProcessor(base, nil)
+		if err != nil || eng != nil {
+			t.Fatalf("buildBurstProcessor = (%v, %v), want (nil, nil)", eng, err)
+		}
+	})
+	t.Run("onboard model equals primary", func(t *testing.T) {
+		base.OnboardSummarizerModel = "koala/phi4-mini"
+		eng, err := buildBurstProcessor(base, nil)
+		if err != nil || eng != nil {
+			t.Fatalf("buildBurstProcessor = (%v, %v), want (nil, nil)", eng, err)
+		}
+	})
+}

internal/adapters/store/videos.go

@@ -86,44 +86,6 @@ func nullDuration(seconds int) *int {
 	return &seconds
 }
 
-// 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
-}
-
 // OnboardBurstVideoIDs returns up to limit of the user's unsummarized videos for
 // the connect-time onboarding burst (ADR-028), newest-first but quality-aware: a
 // video is excluded when its duration is KNOWN and outside [minSeconds, maxSeconds]

internal/adapters/store/videos_test.go

@@ -112,38 +112,6 @@ 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 TestOnboardBurstVideoIDs(t *testing.T) {
 	ctx := context.Background()
 	s := newStore(t)
@@ -158,15 +126,17 @@ func TestOnboardBurstVideoIDs(t *testing.T) {
 		return id
 	}
 
-	good1 := mk(userA, "good0000001", 5, 600)    // 10m, newest known-good
+	summarized := mk(userA, "summ0000001", 6, 600) // newest known-good, but already summarized
+	good1 := mk(userA, "good0000001", 5, 600)      // 10m, newest UNsummarized known-good
 	tooLong := mk(userA, "toolong0001", 4, 20000)  // > maxSeconds -> dropped
-	_ = tooLong
 	tooShort := mk(userA, "tooshort001", 3, 30)    // < minSeconds -> dropped
-	_ = tooShort
 	unknown := mk(userA, "unknown0001", 2, 0)      // NULL duration -> kept, ranked last
 	good2 := mk(userA, "good0000002", 1, 800)      // known-good but oldest
 	mk(userB, "bvid0000009", 9, 600)               // userB -> must not leak via RLS
 
+	// The newest video is summarized, so it is excluded from the burst.
+	require.NoError(t, s.Deliver(ctx, summary(userA, summarized, "done")))
+
 	const minSec, maxSec = 60, 14400
 
 	// Known-good ranked before unknown, each newest-first within its group; the