Add Seriatim configuration contract

internal/config/validate.go

@@ -36,8 +36,7 @@ func validatePipeline(cfg *PipelineConfig) error {
 	if err := validateWhisperX(cfg.WhisperX); err != nil {
 		return err
 	}
-
-	if err := validateDuration("pipeline.seriatim.timeout", cfg.Seriatim.Timeout); err != nil {
+	if err := validateSeriatim(cfg.Seriatim); err != nil {
 		return err
 	}
 	if err := validateDuration("pipeline.audita.timeout", cfg.Audita.Timeout); err != nil {
@@ -85,6 +84,44 @@ func validateWhisperX(cfg WhisperXConfig) error {
 	return nil
 }
 
+func validateSeriatim(cfg SeriatimConfig) error {
+	if strings.TrimSpace(cfg.Binary) == "" {
+		return fmt.Errorf("pipeline.seriatim.binary is required")
+	}
+	if err := validateDuration("pipeline.seriatim.timeout", cfg.Timeout); err != nil {
+		return err
+	}
+
+	switch cfg.OutputSchema {
+	case "seriatim-minimal", "seriatim-intermediate", "seriatim-full":
+	default:
+		return fmt.Errorf("pipeline.seriatim.output_schema must be one of: seriatim-minimal, seriatim-intermediate, seriatim-full")
+	}
+
+	if cfg.CoalesceGap == nil {
+		return fmt.Errorf("pipeline.seriatim.coalesce_gap must be set (defaults should populate this)")
+	}
+	if *cfg.CoalesceGap < 0 {
+		return fmt.Errorf("pipeline.seriatim.coalesce_gap must be >= 0")
+	}
+
+	for _, item := range []struct {
+		name  string
+		value *float64
+	}{
+		{name: "pipeline.seriatim.env.overlap_word_run_gap", value: cfg.Env.OverlapWordRunGap},
+		{name: "pipeline.seriatim.env.overlap_word_run_reorder_window", value: cfg.Env.OverlapWordRunReorderWindow},
+		{name: "pipeline.seriatim.env.backchannel_max_duration", value: cfg.Env.BackchannelMaxDuration},
+		{name: "pipeline.seriatim.env.filler_max_duration", value: cfg.Env.FillerMaxDuration},
+	} {
+		if item.value != nil && *item.value <= 0 {
+			return fmt.Errorf("%s must be > 0 when provided", item.name)
+		}
+	}
+
+	return nil
+}
+
 func validateSession(cfg *SessionConfig) error {
 	if strings.TrimSpace(cfg.SessionID) == "" {
 		return fmt.Errorf("session.session_id is required")