feat(config): add OnboardSummarizerModel + OnboardMaxVideoSeconds (ADR-028)

Two knobs for the onboarding-burst quality work:
- TAPIR_ONBOARD_SUMMARIZER_MODEL (default iguana/gemma4-26b): the stronger model
  the burst leads its chain with; empty collapses the burst onto the shared
  processor (lookupOr, so explicit-empty disables).
- TAPIR_ONBOARD_MAX_VIDEO_SECONDS (default 14400/4h): upper duration bound for
  burst picks; 0 disables, negative clamps to 0.

Table-driven tests cover defaults, explicit, disable, and invalid input.

internal/config/config.go

@@ -120,6 +120,21 @@ type Config struct {
 	// caption rate gate (ADR-014) — the cap bounds count, never the pacing. Default 3.
 	OnboardSummarizeCount int
 
+	// OnboardSummarizerModel is the summarizer alias the connect-time burst leads
+	// its chain with (ADR-028) — a stronger model is affordable on the ≤3 summaries
+	// that form a new user's first impression. It heads a burst-specific chain;
+	// the standard chain (ADR-022) follows as resilience. Empty (or equal to
+	// SummarizerModel) collapses the burst back onto the shared processor — the
+	// reversibility lever. Default iguana/gemma4-26b (the brain-validated model).
+	OnboardSummarizerModel string
+
+	// OnboardMaxVideoSeconds upper-bounds the duration of a video the onboarding
+	// burst will pick (ADR-028), so the burst does not spend a scarce caption fetch
+	// on a multi-hour livestream VOD that passed the live filter once it ended. Only
+	// a KNOWN duration outside [MinVideoSeconds, this] is dropped; a NULL/unknown
+	// duration is kept (degrade-open). 0 disables the upper bound. Default 14400 (4h).
+	OnboardMaxVideoSeconds 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.
@@ -149,26 +164,28 @@ func (c Config) DexConfigured() bool { return strings.TrimSpace(c.OIDCIssuer) !=
 
 // Defaults (see docs/homelab-integration.md). All overridable via env.
 const (
-	defaultGatewayURL            = "http://koala:30401/v1"
+	defaultGatewayURL             = "http://koala:30401/v1"
-	defaultSummarizerModel       = "koala/phi4-mini"
+	defaultSummarizerModel        = "koala/phi4-mini"
-	defaultFallbackModel         = "iguana/gemma4-26b"
+	defaultFallbackModel          = "iguana/gemma4-26b"
-	defaultCloudFallbackModel    = "berget/mistral-small"
+	defaultCloudFallbackModel     = "berget/mistral-small"
-	defaultSummaryMaxTokens      = 1500
+	defaultSummaryMaxTokens       = 1500
-	defaultMaxTranscriptChars    = 18000
+	defaultMaxTranscriptChars     = 18000
-	defaultMinVideoSeconds       = 60
+	defaultMinVideoSeconds        = 60
-	defaultCaptionlessThreshold  = 5
+	defaultCaptionlessThreshold   = 5
-	defaultCaptionlessWindow     = 14 * 24 * time.Hour
+	defaultCaptionlessWindow      = 14 * 24 * time.Hour
-	defaultSummarizerTimeout     = 5 * time.Minute
+	defaultSummarizerTimeout      = 5 * time.Minute
-	defaultYTTokenRef            = "youtube/refresh_token"
+	defaultYTTokenRef             = "youtube/refresh_token"
-	defaultYTConnectRedirectURL  = "https://tapir.d-ma.be/oauth/youtube/callback"
+	defaultYTConnectRedirectURL   = "https://tapir.d-ma.be/oauth/youtube/callback"
-	defaultOAuthRedirectAddr     = "localhost:8080"
+	defaultOAuthRedirectAddr      = "localhost:8080"
-	defaultHTTPAddr              = ":8080"
+	defaultHTTPAddr               = ":8080"
-	defaultFetchBackoff          = time.Hour
+	defaultFetchBackoff           = time.Hour
-	defaultFetchRate             = 2 * time.Second
+	defaultFetchRate              = 2 * time.Second
-	defaultPublicURL             = "https://tapir.d-ma.be"
+	defaultPublicURL              = "https://tapir.d-ma.be"
-	defaultAutoSummarizeWindow   = 7 * 24 * time.Hour
+	defaultAutoSummarizeWindow    = 7 * 24 * time.Hour
-	defaultOnboardSummarizeCount = 3
+	defaultOnboardSummarizeCount  = 3
-	maxOnboardSummarizeCount     = 5
+	maxOnboardSummarizeCount      = 5
+	defaultOnboardSummarizerModel = "iguana/gemma4-26b"
+	defaultOnboardMaxVideoSeconds = 14400 // 4h
 )
 
 // Load reads the environment into a Config, applying defaults. It does not
@@ -177,26 +194,27 @@ const (
 // it needs.
 func Load() (Config, error) {
 	c := Config{
-		UserID:               os.Getenv("TAPIR_USER_ID"),
+		UserID:                 os.Getenv("TAPIR_USER_ID"),
-		GatewayURL:           envOr("TAPIR_GATEWAY_URL", defaultGatewayURL),
+		GatewayURL:             envOr("TAPIR_GATEWAY_URL", defaultGatewayURL),
-		GatewayKey:           os.Getenv("TAPIR_GATEWAY_KEY"),
+		GatewayKey:             os.Getenv("TAPIR_GATEWAY_KEY"),
-		SummarizerModel:      envOr("TAPIR_SUMMARIZER_MODEL", defaultSummarizerModel),
+		SummarizerModel:        envOr("TAPIR_SUMMARIZER_MODEL", defaultSummarizerModel),
-		FallbackModel:        lookupOr("TAPIR_FALLBACK_MODEL", defaultFallbackModel),
+		OnboardSummarizerModel: lookupOr("TAPIR_ONBOARD_SUMMARIZER_MODEL", defaultOnboardSummarizerModel),
-		CloudFallbackModel:   lookupOr("TAPIR_CLOUD_FALLBACK_MODEL", defaultCloudFallbackModel),
+		FallbackModel:          lookupOr("TAPIR_FALLBACK_MODEL", defaultFallbackModel),
-		DBDSN:                os.Getenv("TAPIR_DB_DSN"),
+		CloudFallbackModel:     lookupOr("TAPIR_CLOUD_FALLBACK_MODEL", defaultCloudFallbackModel),
-		YTClientID:           os.Getenv("TAPIR_YT_CLIENT_ID"),
+		DBDSN:                  os.Getenv("TAPIR_DB_DSN"),
-		YTClientSecret:       os.Getenv("TAPIR_YT_CLIENT_SECRET"),
+		YTClientID:             os.Getenv("TAPIR_YT_CLIENT_ID"),
-		YTTokenRef:           envOr("TAPIR_YT_TOKEN_REF", defaultYTTokenRef),
+		YTClientSecret:         os.Getenv("TAPIR_YT_CLIENT_SECRET"),
-		YTConnectRedirectURL: envOr("TAPIR_YT_CONNECT_REDIRECT_URL", defaultYTConnectRedirectURL),
+		YTTokenRef:             envOr("TAPIR_YT_TOKEN_REF", defaultYTTokenRef),
-		SecretsFile:          envOr("TAPIR_SECRETS_FILE", defaultSecretsFile()),
+		YTConnectRedirectURL:   envOr("TAPIR_YT_CONNECT_REDIRECT_URL", defaultYTConnectRedirectURL),
-		OAuthRedirectAddr:    envOr("TAPIR_OAUTH_REDIRECT_ADDR", defaultOAuthRedirectAddr),
+		SecretsFile:            envOr("TAPIR_SECRETS_FILE", defaultSecretsFile()),
-		HTTPAddr:             envOr("TAPIR_HTTP_ADDR", defaultHTTPAddr),
+		OAuthRedirectAddr:      envOr("TAPIR_OAUTH_REDIRECT_ADDR", defaultOAuthRedirectAddr),
-		PublicURL:            envOr("TAPIR_PUBLIC_URL", defaultPublicURL),
+		HTTPAddr:               envOr("TAPIR_HTTP_ADDR", defaultHTTPAddr),
-		OIDCIssuer:           os.Getenv("TAPIR_OIDC_ISSUER"),
+		PublicURL:              envOr("TAPIR_PUBLIC_URL", defaultPublicURL),
-		DexClientID:          os.Getenv("TAPIR_DEX_CLIENT_ID"),
+		OIDCIssuer:             os.Getenv("TAPIR_OIDC_ISSUER"),
-		DexClientSecret:      os.Getenv("TAPIR_DEX_CLIENT_SECRET"),
+		DexClientID:            os.Getenv("TAPIR_DEX_CLIENT_ID"),
-		OIDCRedirectURL:      os.Getenv("TAPIR_OIDC_REDIRECT_URL"),
+		DexClientSecret:        os.Getenv("TAPIR_DEX_CLIENT_SECRET"),
-		SessionSecret:        os.Getenv("TAPIR_SESSION_SECRET"),
+		OIDCRedirectURL:        os.Getenv("TAPIR_OIDC_REDIRECT_URL"),
+		SessionSecret:          os.Getenv("TAPIR_SESSION_SECRET"),
 	}
 
 	timeout, err := durationOr("TAPIR_SUMMARIZER_TIMEOUT", defaultSummarizerTimeout)
@@ -286,6 +304,15 @@ func Load() (Config, error) {
 	}
 	c.OnboardSummarizeCount = onboard
 
+	onboardMax, err := intOr("TAPIR_ONBOARD_MAX_VIDEO_SECONDS", defaultOnboardMaxVideoSeconds)
+	if err != nil {
+		return Config{}, err
+	}
+	if onboardMax < 0 {
+		onboardMax = 0
+	}
+	c.OnboardMaxVideoSeconds = onboardMax
+
 	return c, nil
 }
 

internal/config/config_test.go

@@ -214,3 +214,62 @@ func TestValidateForAuth_PassesWhenComplete(t *testing.T) {
 		t.Errorf("ValidateForAuth: unexpected error %v", err)
 	}
 }
+
+func TestLoad_OnboardSummarizerModel(t *testing.T) {
+	cases := []struct {
+		name, env string
+		set       bool
+		want      string
+	}{
+		{"default", "", false, defaultOnboardSummarizerModel},
+		{"explicit", "koala/some-model", true, "koala/some-model"},
+		{"empty disables (collapses to shared processor)", "", true, ""},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			env := map[string]string{}
+			if c.set {
+				env["TAPIR_ONBOARD_SUMMARIZER_MODEL"] = c.env
+			}
+			setEnv(t, env)
+			cfg, err := Load()
+			if err != nil {
+				t.Fatalf("Load: %v", err)
+			}
+			if cfg.OnboardSummarizerModel != c.want {
+				t.Fatalf("OnboardSummarizerModel = %q, want %q", cfg.OnboardSummarizerModel, c.want)
+			}
+		})
+	}
+}
+
+func TestLoad_OnboardMaxVideoSeconds(t *testing.T) {
+	cases := []struct {
+		name, env string
+		want      int
+	}{
+		{"default", "", defaultOnboardMaxVideoSeconds},
+		{"explicit", "7200", 7200},
+		{"zero disables", "0", 0},
+		{"negative clamps to zero", "-9", 0},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			setEnv(t, map[string]string{"TAPIR_ONBOARD_MAX_VIDEO_SECONDS": c.env})
+			cfg, err := Load()
+			if err != nil {
+				t.Fatalf("Load: %v", err)
+			}
+			if cfg.OnboardMaxVideoSeconds != c.want {
+				t.Fatalf("OnboardMaxVideoSeconds = %d, want %d", cfg.OnboardMaxVideoSeconds, c.want)
+			}
+		})
+	}
+}
+
+func TestLoad_OnboardMaxVideoSecondsInvalid(t *testing.T) {
+	setEnv(t, map[string]string{"TAPIR_ONBOARD_MAX_VIDEO_SECONDS": "long"})
+	if _, err := Load(); err == nil {
+		t.Fatal("Load: want error for non-numeric TAPIR_ONBOARD_MAX_VIDEO_SECONDS")
+	}
+}