diff --git a/processors/normalize/helpers.go b/processors/normalize/helpers.go
new file mode 100644
index 0000000..3a43204
--- /dev/null
+++ b/processors/normalize/helpers.go
@@ -0,0 +1,84 @@
+package normalize
+
+import (
+	"encoding/json"
+	"fmt"
+	"time"
+
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+)
+
+// PayloadJSONBytes extracts a JSON payload into bytes suitable for json.Unmarshal.
+//
+// Supported payload shapes:
+//   - json.RawMessage
+//   - []byte
+//   - string
+//   - map[string]any
+func PayloadJSONBytes(e event.Event) ([]byte, error) {
+	if e.Payload == nil {
+		return nil, fmt.Errorf("payload is nil")
+	}
+
+	switch v := e.Payload.(type) {
+	case json.RawMessage:
+		if len(v) == 0 {
+			return nil, fmt.Errorf("payload is empty json.RawMessage")
+		}
+		return []byte(v), nil
+	case []byte:
+		if len(v) == 0 {
+			return nil, fmt.Errorf("payload is empty []byte")
+		}
+		return v, nil
+	case string:
+		if v == "" {
+			return nil, fmt.Errorf("payload is empty string")
+		}
+		return []byte(v), nil
+	case map[string]any:
+		b, err := json.Marshal(v)
+		if err != nil {
+			return nil, fmt.Errorf("marshal map payload: %w", err)
+		}
+		return b, nil
+	default:
+		return nil, fmt.Errorf("unsupported payload type %T", e.Payload)
+	}
+}
+
+// DecodeJSONPayload extracts the event payload as bytes and unmarshals it into T.
+func DecodeJSONPayload[T any](in event.Event) (T, error) {
+	var zero T
+
+	b, err := PayloadJSONBytes(in)
+	if err != nil {
+		return zero, fmt.Errorf("extract payload: %w", err)
+	}
+
+	var parsed T
+	if err := json.Unmarshal(b, &parsed); err != nil {
+		return zero, fmt.Errorf("decode raw payload: %w", err)
+	}
+
+	return parsed, nil
+}
+
+// FinalizeEvent builds the output event envelope by copying the input and applying
+// the new schema/payload, plus optional EffectiveAt.
+func FinalizeEvent(in event.Event, outSchema string, outPayload any, effectiveAt time.Time) (*event.Event, error) {
+	out := in
+	out.Schema = outSchema
+	out.Payload = outPayload
+
+	if !effectiveAt.IsZero() {
+		t := effectiveAt.UTC()
+		out.EffectiveAt = &t
+	}
+
+	if err := out.Validate(); err != nil {
+		return nil, err
+	}
+
+	return &out, nil
+}
diff --git a/processors/normalize/helpers_test.go b/processors/normalize/helpers_test.go
new file mode 100644
index 0000000..c01e7c3
--- /dev/null
+++ b/processors/normalize/helpers_test.go
@@ -0,0 +1,118 @@
+package normalize
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+	"time"
+
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+)
+
+func TestPayloadJSONBytesSupportedShapes(t *testing.T) {
+	cases := []struct {
+		name    string
+		payload any
+		want    string
+	}{
+		{name: "rawmessage", payload: json.RawMessage(`{"a":1}`), want: `{"a":1}`},
+		{name: "bytes", payload: []byte(`{"a":2}`), want: `{"a":2}`},
+		{name: "string", payload: `{"a":3}`, want: `{"a":3}`},
+		{name: "map", payload: map[string]any{"a": 4}, want: `{"a":4}`},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			got, err := PayloadJSONBytes(event.Event{Payload: tc.payload})
+			if err != nil {
+				t.Fatalf("PayloadJSONBytes() unexpected error: %v", err)
+			}
+			if string(got) != tc.want {
+				t.Fatalf("PayloadJSONBytes() = %s, want %s", string(got), tc.want)
+			}
+		})
+	}
+}
+
+func TestPayloadJSONBytesRejectsInvalidPayloads(t *testing.T) {
+	cases := []struct {
+		name    string
+		payload any
+		want    string
+	}{
+		{name: "nil", payload: nil, want: "payload is nil"},
+		{name: "empty rawmessage", payload: json.RawMessage{}, want: "payload is empty json.RawMessage"},
+		{name: "empty bytes", payload: []byte{}, want: "payload is empty []byte"},
+		{name: "empty string", payload: "", want: "payload is empty string"},
+		{name: "unsupported", payload: 123, want: "unsupported payload type"},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			_, err := PayloadJSONBytes(event.Event{Payload: tc.payload})
+			if err == nil {
+				t.Fatalf("PayloadJSONBytes() expected error")
+			}
+			if !strings.Contains(err.Error(), tc.want) {
+				t.Fatalf("PayloadJSONBytes() error = %q, want substring %q", err, tc.want)
+			}
+		})
+	}
+}
+
+func TestDecodeJSONPayload(t *testing.T) {
+	type payload struct {
+		Name string `json:"name"`
+	}
+
+	got, err := DecodeJSONPayload[payload](event.Event{
+		Payload: json.RawMessage(`{"name":"alice"}`),
+	})
+	if err != nil {
+		t.Fatalf("DecodeJSONPayload() unexpected error: %v", err)
+	}
+	if got.Name != "alice" {
+		t.Fatalf("DecodeJSONPayload() = %#v, want name alice", got)
+	}
+}
+
+func TestFinalizeEventPreservesEnvelopeAndEffectiveAtBehavior(t *testing.T) {
+	existingEffectiveAt := time.Date(2026, 3, 28, 11, 0, 0, 0, time.UTC)
+	in := event.Event{
+		ID:          "evt-1",
+		Kind:        event.Kind("observation"),
+		Source:      "source-a",
+		EmittedAt:   time.Date(2026, 3, 28, 12, 0, 0, 0, time.UTC),
+		EffectiveAt: &existingEffectiveAt,
+		Schema:      "raw.example.v1",
+		Payload:     map[string]any{"old": true},
+	}
+
+	out, err := FinalizeEvent(in, "example.v1", map[string]any{"value": 1.234567}, time.Time{})
+	if err != nil {
+		t.Fatalf("FinalizeEvent() unexpected error: %v", err)
+	}
+	if out.ID != in.ID || out.Kind != in.Kind || out.Source != in.Source || out.EmittedAt != in.EmittedAt {
+		t.Fatalf("FinalizeEvent() changed preserved envelope fields: %#v", out)
+	}
+	if out.EffectiveAt == nil || !out.EffectiveAt.Equal(existingEffectiveAt) {
+		t.Fatalf("FinalizeEvent() effectiveAt = %#v, want preserved existing value", out.EffectiveAt)
+	}
+
+	nextEffectiveAt := time.Date(2026, 3, 28, 13, 0, 0, 0, time.FixedZone("x", -4*3600))
+	out, err = FinalizeEvent(in, "example.v1", map[string]any{"value": 1.234567}, nextEffectiveAt)
+	if err != nil {
+		t.Fatalf("FinalizeEvent() unexpected overwrite error: %v", err)
+	}
+	if out.EffectiveAt == nil || !out.EffectiveAt.Equal(nextEffectiveAt.UTC()) {
+		t.Fatalf("FinalizeEvent() effectiveAt = %#v, want %s", out.EffectiveAt, nextEffectiveAt.UTC())
+	}
+
+	payloadMap, ok := out.Payload.(map[string]any)
+	if !ok {
+		t.Fatalf("FinalizeEvent() payload type = %T, want map[string]any", out.Payload)
+	}
+	if payloadMap["value"] != 1.234567 {
+		t.Fatalf("FinalizeEvent() payload value = %#v, want unrounded 1.234567", payloadMap["value"])
+	}
+}
diff --git a/sinks/helpers.go b/sinks/helpers.go
new file mode 100644
index 0000000..3188f94
--- /dev/null
+++ b/sinks/helpers.go
@@ -0,0 +1,27 @@
+package sinks
+
+import (
+	"fmt"
+	"strings"
+
+	"gitea.maximumdirect.net/ejr/feedkit/config"
+)
+
+// RegisterPostgresSchemaForConfiguredSinks registers one Postgres schema for each
+// configured sink using driver=postgres.
+func RegisterPostgresSchemaForConfiguredSinks(cfg *config.Config, schema PostgresSchema) error {
+	if cfg == nil {
+		return fmt.Errorf("register postgres schemas: config is nil")
+	}
+
+	for i, sk := range cfg.Sinks {
+		if !strings.EqualFold(strings.TrimSpace(sk.Driver), "postgres") {
+			continue
+		}
+		if err := RegisterPostgresSchema(sk.Name, schema); err != nil {
+			return fmt.Errorf("register postgres schema for sinks[%d] name=%q: %w", i, sk.Name, err)
+		}
+	}
+
+	return nil
+}
diff --git a/sinks/helpers_test.go b/sinks/helpers_test.go
new file mode 100644
index 0000000..8e318bd
--- /dev/null
+++ b/sinks/helpers_test.go
@@ -0,0 +1,86 @@
+package sinks
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"testing"
+	"time"
+
+	"gitea.maximumdirect.net/ejr/feedkit/config"
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+)
+
+func TestRegisterPostgresSchemaForConfiguredSinksNilConfig(t *testing.T) {
+	err := RegisterPostgresSchemaForConfiguredSinks(nil, testPostgresSchema())
+	if err == nil {
+		t.Fatalf("RegisterPostgresSchemaForConfiguredSinks(nil) expected error")
+	}
+	if !strings.Contains(err.Error(), "config is nil") {
+		t.Fatalf("error = %q, want config is nil", err)
+	}
+}
+
+func TestRegisterPostgresSchemaForConfiguredSinksNonPostgresNoOp(t *testing.T) {
+	cfg := &config.Config{
+		Sinks: []config.SinkConfig{
+			{Name: uniqueSinkName("stdout"), Driver: "stdout"},
+			{Name: uniqueSinkName("nats"), Driver: "nats"},
+		},
+	}
+
+	if err := RegisterPostgresSchemaForConfiguredSinks(cfg, testPostgresSchema()); err != nil {
+		t.Fatalf("RegisterPostgresSchemaForConfiguredSinks(non-postgres) error = %v", err)
+	}
+}
+
+func TestRegisterPostgresSchemaForConfiguredSinksDuplicateRegistrationFails(t *testing.T) {
+	cfg := &config.Config{
+		Sinks: []config.SinkConfig{
+			{Name: uniqueSinkName("pg"), Driver: "postgres"},
+		},
+	}
+
+	if err := RegisterPostgresSchemaForConfiguredSinks(cfg, testPostgresSchema()); err != nil {
+		t.Fatalf("first RegisterPostgresSchemaForConfiguredSinks() error = %v", err)
+	}
+
+	err := RegisterPostgresSchemaForConfiguredSinks(cfg, testPostgresSchema())
+	if err == nil {
+		t.Fatalf("second RegisterPostgresSchemaForConfiguredSinks() expected duplicate error")
+	}
+	if !strings.Contains(err.Error(), "already registered") {
+		t.Fatalf("error = %q, want already registered", err)
+	}
+}
+
+func testPostgresSchema() PostgresSchema {
+	return PostgresSchema{
+		Tables: []PostgresTable{
+			{
+				Name: "events",
+				Columns: []PostgresColumn{
+					{Name: "event_id", Type: "TEXT", Nullable: false},
+					{Name: "emitted_at", Type: "TIMESTAMPTZ", Nullable: false},
+				},
+				PrimaryKey:  []string{"event_id"},
+				PruneColumn: "emitted_at",
+			},
+		},
+		MapEvent: func(_ context.Context, e event.Event) ([]PostgresWrite, error) {
+			return []PostgresWrite{
+				{
+					Table: "events",
+					Values: map[string]any{
+						"event_id":   e.ID,
+						"emitted_at": e.EmittedAt,
+					},
+				},
+			}, nil
+		},
+	}
+}
+
+func uniqueSinkName(prefix string) string {
+	return fmt.Sprintf("%s_%d", prefix, time.Now().UnixNano())
+}
diff --git a/sources/helpers.go b/sources/helpers.go
new file mode 100644
index 0000000..2984ab9
--- /dev/null
+++ b/sources/helpers.go
@@ -0,0 +1,145 @@
+package sources
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+	"time"
+
+	"gitea.maximumdirect.net/ejr/feedkit/config"
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+)
+
+// DefaultEventID applies feedkit's default Event.ID policy:
+//
+//   - If upstream provides an ID, use it (trimmed).
+//   - Otherwise, ID is "<Source>:<EffectiveAt>" when available.
+//   - If EffectiveAt is unavailable, fall back to "<Source>:<EmittedAt>".
+//
+// Timestamps are encoded as RFC3339Nano in UTC.
+func DefaultEventID(upstreamID, sourceName string, effectiveAt *time.Time, emittedAt time.Time) string {
+	if id := strings.TrimSpace(upstreamID); id != "" {
+		return id
+	}
+
+	src := strings.TrimSpace(sourceName)
+	if src == "" {
+		src = "UNKNOWN_SOURCE"
+	}
+
+	if effectiveAt != nil && !effectiveAt.IsZero() {
+		return fmt.Sprintf("%s:%s", src, effectiveAt.UTC().Format(time.RFC3339Nano))
+	}
+
+	t := emittedAt.UTC()
+	if t.IsZero() {
+		t = time.Now().UTC()
+	}
+
+	return fmt.Sprintf("%s:%s", src, t.Format(time.RFC3339Nano))
+}
+
+// SingleEvent constructs, validates, and returns a slice containing exactly one event.
+func SingleEvent(
+	kind event.Kind,
+	sourceName string,
+	schema string,
+	id string,
+	emittedAt time.Time,
+	effectiveAt *time.Time,
+	payload any,
+) ([]event.Event, error) {
+	if emittedAt.IsZero() {
+		emittedAt = time.Now().UTC()
+	} else {
+		emittedAt = emittedAt.UTC()
+	}
+
+	e := event.Event{
+		ID:          id,
+		Kind:        kind,
+		Source:      sourceName,
+		EmittedAt:   emittedAt,
+		EffectiveAt: effectiveAt,
+		Schema:      schema,
+		Payload:     payload,
+	}
+
+	if err := e.Validate(); err != nil {
+		return nil, err
+	}
+
+	return []event.Event{e}, nil
+}
+
+// ValidateExpectedKinds checks that configured source expected kinds are a subset
+// of the kinds advertised by the built source, when the source exposes kind
+// metadata. If the source does not advertise kinds, the check is skipped.
+func ValidateExpectedKinds(cfg config.SourceConfig, in Input) error {
+	expectedKinds, err := parseExpectedKinds(cfg.ExpectedKinds())
+	if err != nil {
+		return err
+	}
+	if len(expectedKinds) == 0 {
+		return nil
+	}
+
+	advertisedKinds := advertisedSourceKinds(in)
+	if len(advertisedKinds) == 0 {
+		return nil
+	}
+
+	for kind := range expectedKinds {
+		if !advertisedKinds[kind] {
+			return fmt.Errorf(
+				"configured expected kind %q not advertised by source (configured=%v advertised=%v)",
+				kind,
+				sortedKinds(expectedKinds),
+				sortedKinds(advertisedKinds),
+			)
+		}
+	}
+	return nil
+}
+
+func parseExpectedKinds(raw []string) (map[event.Kind]bool, error) {
+	kinds := map[event.Kind]bool{}
+	for i, k := range raw {
+		kind, err := event.ParseKind(k)
+		if err != nil {
+			return nil, fmt.Errorf("invalid expected kind at index %d (%q): %w", i, k, err)
+		}
+		kinds[kind] = true
+	}
+	return kinds, nil
+}
+
+func advertisedSourceKinds(in Input) map[event.Kind]bool {
+	if in == nil {
+		return nil
+	}
+
+	kinds := map[event.Kind]bool{}
+	if ks, ok := in.(KindsSource); ok {
+		for _, kind := range ks.Kinds() {
+			kinds[kind] = true
+		}
+		return kinds
+	}
+
+	if ks, ok := in.(KindSource); ok {
+		kinds[ks.Kind()] = true
+		return kinds
+	}
+
+	return nil
+}
+
+func sortedKinds(kindSet map[event.Kind]bool) []string {
+	out := make([]string, 0, len(kindSet))
+	for kind := range kindSet {
+		out = append(out, string(kind))
+	}
+	sort.Strings(out)
+	return out
+}
diff --git a/sources/helpers_test.go b/sources/helpers_test.go
new file mode 100644
index 0000000..57d4f8a
--- /dev/null
+++ b/sources/helpers_test.go
@@ -0,0 +1,131 @@
+package sources
+
+import (
+	"strings"
+	"testing"
+	"time"
+
+	"gitea.maximumdirect.net/ejr/feedkit/config"
+	"gitea.maximumdirect.net/ejr/feedkit/event"
+)
+
+type testInput struct {
+	name string
+}
+
+func (s testInput) Name() string { return s.name }
+
+type testKindSource struct {
+	testInput
+	kind event.Kind
+}
+
+func (s testKindSource) Kind() event.Kind { return s.kind }
+
+type testKindsSource struct {
+	testInput
+	kinds []event.Kind
+}
+
+func (s testKindsSource) Kinds() []event.Kind { return s.kinds }
+
+func TestValidateExpectedKindsLegacyKindFallback(t *testing.T) {
+	cfg := config.SourceConfig{Kind: "observation"}
+	in := testKindSource{
+		testInput: testInput{name: "test"},
+		kind:      event.Kind("observation"),
+	}
+
+	if err := ValidateExpectedKinds(cfg, in); err != nil {
+		t.Fatalf("ValidateExpectedKinds() unexpected error: %v", err)
+	}
+}
+
+func TestValidateExpectedKindsSubsetAllowed(t *testing.T) {
+	cfg := config.SourceConfig{Kinds: []string{"observation"}}
+	in := testKindsSource{
+		testInput: testInput{name: "test"},
+		kinds:     []event.Kind{"observation", "forecast"},
+	}
+
+	if err := ValidateExpectedKinds(cfg, in); err != nil {
+		t.Fatalf("ValidateExpectedKinds() unexpected error: %v", err)
+	}
+}
+
+func TestValidateExpectedKindsMismatchFails(t *testing.T) {
+	cfg := config.SourceConfig{Kinds: []string{"alert"}}
+	in := testKindsSource{
+		testInput: testInput{name: "test"},
+		kinds:     []event.Kind{"observation", "forecast"},
+	}
+
+	err := ValidateExpectedKinds(cfg, in)
+	if err == nil {
+		t.Fatalf("ValidateExpectedKinds() expected mismatch error, got nil")
+	}
+	if !strings.Contains(err.Error(), "configured expected kind") {
+		t.Fatalf("ValidateExpectedKinds() error %q does not include expected message", err)
+	}
+}
+
+func TestValidateExpectedKindsNoMetadataSkipsCheck(t *testing.T) {
+	cfg := config.SourceConfig{Kinds: []string{"alert"}}
+	in := testInput{name: "test"}
+
+	if err := ValidateExpectedKinds(cfg, in); err != nil {
+		t.Fatalf("ValidateExpectedKinds() unexpected error: %v", err)
+	}
+}
+
+func TestDefaultEventIDUsesUpstreamID(t *testing.T) {
+	emittedAt := time.Date(2026, 3, 28, 15, 4, 5, 123, time.UTC)
+	got := DefaultEventID(" upstream-id ", "source", nil, emittedAt)
+	if got != "upstream-id" {
+		t.Fatalf("DefaultEventID() = %q, want upstream-id", got)
+	}
+}
+
+func TestDefaultEventIDPrefersEffectiveAt(t *testing.T) {
+	effectiveAt := time.Date(2026, 3, 28, 16, 4, 5, 987654321, time.FixedZone("x", -6*3600))
+	emittedAt := time.Date(2026, 3, 28, 15, 4, 5, 123, time.UTC)
+
+	got := DefaultEventID("", "source", &effectiveAt, emittedAt)
+	want := "source:" + effectiveAt.UTC().Format(time.RFC3339Nano)
+	if got != want {
+		t.Fatalf("DefaultEventID() = %q, want %q", got, want)
+	}
+}
+
+func TestDefaultEventIDFallsBackToEmittedAt(t *testing.T) {
+	emittedAt := time.Date(2026, 3, 28, 15, 4, 5, 123456789, time.FixedZone("y", 3*3600))
+	got := DefaultEventID("", "source", nil, emittedAt)
+	want := "source:" + emittedAt.UTC().Format(time.RFC3339Nano)
+	if got != want {
+		t.Fatalf("DefaultEventID() = %q, want %q", got, want)
+	}
+}
+
+func TestSingleEventBuildsValidatedSlice(t *testing.T) {
+	effectiveAt := time.Date(2026, 3, 28, 16, 0, 0, 0, time.UTC)
+	emittedAt := time.Date(2026, 3, 28, 15, 0, 0, 0, time.FixedZone("z", -5*3600))
+
+	got, err := SingleEvent(
+		event.Kind("observation"),
+		"source-a",
+		"raw.example.v1",
+		"evt-1",
+		emittedAt,
+		&effectiveAt,
+		map[string]any{"ok": true},
+	)
+	if err != nil {
+		t.Fatalf("SingleEvent() unexpected error: %v", err)
+	}
+	if len(got) != 1 {
+		t.Fatalf("SingleEvent() len = %d, want 1", len(got))
+	}
+	if got[0].EmittedAt != emittedAt.UTC() {
+		t.Fatalf("SingleEvent() emittedAt = %s, want %s", got[0].EmittedAt, emittedAt.UTC())
+	}
+}