diff --git a/cmd/deklarix/main.go b/cmd/deklarix/main.go
index d6dc1fb..7aef706 100644
--- a/cmd/deklarix/main.go
+++ b/cmd/deklarix/main.go
@@ -1,13 +1,31 @@
 package main
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"net/http"
 	"os"
+
+	"github.com/netcell-it/deklarix/internal/store"
 )
 
 func main() {
+	databaseURL := os.Getenv("DATABASE_URL")
+	if databaseURL == "" {
+		log.Fatal("DATABASE_URL is required")
+	}
+
+	if err := store.Migrate(databaseURL); err != nil {
+		log.Fatalf("migrate: %v", err)
+	}
+
+	db, err := store.Open(context.Background(), databaseURL)
+	if err != nil {
+		log.Fatalf("open store: %v", err)
+	}
+	defer db.Close()
+
 	port := os.Getenv("PORT")
 	if port == "" {
 		port = "8080"
diff --git a/go.mod b/go.mod
index baf539e..7597174 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,14 @@
 module github.com/netcell-it/deklarix
 
 go 1.26.6
+
+require (
+	github.com/golang-migrate/migrate/v4 v4.19.1 // indirect
+	github.com/jackc/pgerrcode v0.0.0-20220416144525-469b46aa5efa // indirect
+	github.com/jackc/pgpassfile v1.0.0 // indirect
+	github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect
+	github.com/jackc/pgx/v5 v5.10.0 // indirect
+	github.com/jackc/puddle/v2 v2.2.2 // indirect
+	golang.org/x/sync v0.18.0 // indirect
+	golang.org/x/text v0.31.0 // indirect
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..8ce40dc
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,23 @@
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/golang-migrate/migrate/v4 v4.19.1 h1:OCyb44lFuQfYXYLx1SCxPZQGU7mcaZ7gH9yH4jSFbBA=
+github.com/golang-migrate/migrate/v4 v4.19.1/go.mod h1:CTcgfjxhaUtsLipnLoQRWCrjYXycRz/g5+RWDuYgPrE=
+github.com/jackc/pgerrcode v0.0.0-20220416144525-469b46aa5efa h1:s+4MhCQ6YrzisK6hFJUX53drDT4UsSW3DEhKn0ifuHw=
+github.com/jackc/pgerrcode v0.0.0-20220416144525-469b46aa5efa/go.mod h1:a/s9Lp5W7n/DD0VrVoyJ00FbP2ytTPDVOivvn2bMlds=
+github.com/jackc/pgpassfile v1.0.0 h1:/6Hmqy13Ss2zCq62VdNG8tM1wchn8zjSGOBJ6icpsIM=
+github.com/jackc/pgpassfile v1.0.0/go.mod h1:CEx0iS5ambNFdcRtxPj5JhEz+xB6uRky5eyVu/W2HEg=
+github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 h1:iCEnooe7UlwOQYpKFhBabPMi4aNAfoODPEFNiAnClxo=
+github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761/go.mod h1:5TJZWKEWniPve33vlWYSoGYefn3gLQRzjfDlhSJ9ZKM=
+github.com/jackc/pgx/v5 v5.10.0 h1:VhSvgU2jSli8o3AqIEOTJr7rZwAEUVo4E4XhR94Zfr0=
+github.com/jackc/pgx/v5 v5.10.0/go.mod h1:mal1tBGAFfLHvZzaYh77YS/eC6IX9OWbRV1QIIM0Jn4=
+github.com/jackc/puddle/v2 v2.2.2 h1:PR8nw+E/1w0GLuRFSmiioY6UooMp6KJv0/61nB7icHo=
+github.com/jackc/puddle/v2 v2.2.2/go.mod h1:vriiEXHvEE654aYKXXjOvZM39qJ0q+azkZFrfEOc3H4=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+golang.org/x/sync v0.18.0 h1:kr88TuHDroi+UVf+0hZnirlk8o8T+4MrK6mr60WkH/I=
+golang.org/x/sync v0.18.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
+golang.org/x/text v0.31.0 h1:aC8ghyu4JhP8VojJ2lEHBnochRno1sgL6nEi9WGFGMM=
+golang.org/x/text v0.31.0/go.mod h1:tKRAlv61yKIjGGHX/4tP1LTbc13YSec1pxVEWXzfoeM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/internal/store/migrate.go b/internal/store/migrate.go
new file mode 100644
index 0000000..fd26936
--- /dev/null
+++ b/internal/store/migrate.go
@@ -0,0 +1,48 @@
+package store
+
+import (
+	"database/sql"
+	"embed"
+	"errors"
+	"fmt"
+
+	"github.com/golang-migrate/migrate/v4"
+	pgxmigrate "github.com/golang-migrate/migrate/v4/database/pgx/v5"
+	"github.com/golang-migrate/migrate/v4/source/iofs"
+	_ "github.com/jackc/pgx/v5/stdlib"
+)
+
+//go:embed migrations/*.sql
+var migrationsFS embed.FS
+
+// Migrate wendet alle ausstehenden Migrationen aus migrations/ an.
+// Die Migrationen sind im Binary eingebettet (go:embed), damit Deklarix
+// weiterhin als einzelnes Binary lauffähig bleibt.
+func Migrate(databaseURL string) error {
+	db, err := sql.Open("pgx", databaseURL)
+	if err != nil {
+		return fmt.Errorf("store: open db for migration: %w", err)
+	}
+	defer db.Close()
+
+	driver, err := pgxmigrate.WithInstance(db, &pgxmigrate.Config{})
+	if err != nil {
+		return fmt.Errorf("store: migration driver: %w", err)
+	}
+
+	source, err := iofs.New(migrationsFS, "migrations")
+	if err != nil {
+		return fmt.Errorf("store: migration source: %w", err)
+	}
+
+	m, err := migrate.NewWithInstance("iofs", source, "pgx5", driver)
+	if err != nil {
+		return fmt.Errorf("store: migrate init: %w", err)
+	}
+	defer m.Close()
+
+	if err := m.Up(); err != nil && !errors.Is(err, migrate.ErrNoChange) {
+		return fmt.Errorf("store: migrate up: %w", err)
+	}
+	return nil
+}
diff --git a/internal/store/migrations/0001_init.down.sql b/internal/store/migrations/0001_init.down.sql
new file mode 100644
index 0000000..dc451ff
--- /dev/null
+++ b/internal/store/migrations/0001_init.down.sql
@@ -0,0 +1,11 @@
+DROP TRIGGER IF EXISTS evidence_package_append_only ON evidence_package;
+DROP TRIGGER IF EXISTS finding_append_only ON finding;
+DROP TRIGGER IF EXISTS extraction_append_only ON extraction;
+DROP FUNCTION IF EXISTS forbid_update_delete();
+
+DROP TABLE IF EXISTS participant;
+DROP TABLE IF EXISTS evidence_package;
+DROP TABLE IF EXISTS finding;
+DROP TABLE IF EXISTS extraction;
+DROP TABLE IF EXISTS asset;
+DROP TABLE IF EXISTS submission;
diff --git a/internal/store/migrations/0001_init.up.sql b/internal/store/migrations/0001_init.up.sql
new file mode 100644
index 0000000..ee1190f
--- /dev/null
+++ b/internal/store/migrations/0001_init.up.sql
@@ -0,0 +1,89 @@
+CREATE EXTENSION IF NOT EXISTS pgcrypto;
+
+CREATE TABLE submission (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    platform TEXT NOT NULL CHECK (platform IN ('instagram', 'tiktok', 'youtube', 'linkedin')),
+    post_type TEXT NOT NULL,
+    status TEXT NOT NULL DEFAULT 'draft' CHECK (status IN ('draft', 'checked', 'published', 'archived')),
+    caption TEXT,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+
+CREATE TABLE asset (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    submission_id UUID NOT NULL REFERENCES submission (id),
+    kind TEXT NOT NULL CHECK (kind IN ('image', 'video', 'file')),
+    path TEXT NOT NULL,
+    sha256 TEXT NOT NULL,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+
+-- Stufe 1: striktes JSON aus der Claude-Extraktion. Append-only, siehe Trigger unten.
+CREATE TABLE extraction (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    submission_id UUID NOT NULL REFERENCES submission (id),
+    payload JSONB NOT NULL,
+    model_version TEXT NOT NULL,
+    prompt_version TEXT NOT NULL,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+
+-- Stufe 2: Ergebnis pro Regel. Append-only, Korrektur = neue Zeile.
+-- supersedes zeigt auf die alte Zeile, die diese Zeile ersetzt (gesetzt
+-- beim INSERT der Korrektur, nie per UPDATE — der Trigger würde das
+-- verbieten). "Aktuell gültig" = Zeilen, auf die kein supersedes zeigt,
+-- siehe Index unten für den Anti-Join.
+CREATE TABLE finding (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    submission_id UUID NOT NULL REFERENCES submission (id),
+    extraction_id UUID REFERENCES extraction (id),
+    rule_id TEXT NOT NULL,
+    rule_version INTEGER NOT NULL,
+    severity TEXT NOT NULL CHECK (severity IN ('niedrig', 'mittel', 'hoch')),
+    message TEXT NOT NULL,
+    supersedes UUID REFERENCES finding (id),
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+
+CREATE INDEX finding_supersedes_idx ON finding (supersedes) WHERE supersedes IS NOT NULL;
+
+-- Dossier + Beweiskette (Hash, RFC-3161-Token). Append-only.
+CREATE TABLE evidence_package (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    submission_id UUID NOT NULL REFERENCES submission (id),
+    dossier_path TEXT NOT NULL,
+    sha256 TEXT NOT NULL,
+    timestamp_token BYTEA NOT NULL,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+
+CREATE TABLE participant (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    submission_id UUID NOT NULL REFERENCES submission (id),
+    role TEXT NOT NULL CHECK (role IN ('creator', 'agentur', 'marke', 'kanzlei')),
+    name TEXT NOT NULL,
+    vorgegeben BOOLEAN NOT NULL DEFAULT false,
+    freigegeben BOOLEAN NOT NULL DEFAULT false,
+    approved_at TIMESTAMPTZ,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+
+-- Ein Beweisarchiv, in dem man Zeilen ändern kann, ist kein Beweisarchiv.
+CREATE FUNCTION forbid_update_delete() RETURNS TRIGGER AS $$
+BEGIN
+    RAISE EXCEPTION 'append-only table: % on % is not allowed', TG_OP, TG_TABLE_NAME;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE TRIGGER extraction_append_only
+    BEFORE UPDATE OR DELETE ON extraction
+    FOR EACH ROW EXECUTE FUNCTION forbid_update_delete();
+
+CREATE TRIGGER finding_append_only
+    BEFORE UPDATE OR DELETE ON finding
+    FOR EACH ROW EXECUTE FUNCTION forbid_update_delete();
+
+CREATE TRIGGER evidence_package_append_only
+    BEFORE UPDATE OR DELETE ON evidence_package
+    FOR EACH ROW EXECUTE FUNCTION forbid_update_delete();
diff --git a/internal/store/store.go b/internal/store/store.go
new file mode 100644
index 0000000..927983e
--- /dev/null
+++ b/internal/store/store.go
@@ -0,0 +1,31 @@
+package store
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+// Store hält den Verbindungspool zur Postgres-Datenbank.
+type Store struct {
+	Pool *pgxpool.Pool
+}
+
+// Open baut den Verbindungspool auf und prüft ihn mit einem Ping.
+func Open(ctx context.Context, databaseURL string) (*Store, error) {
+	pool, err := pgxpool.New(ctx, databaseURL)
+	if err != nil {
+		return nil, fmt.Errorf("store: open pool: %w", err)
+	}
+	if err := pool.Ping(ctx); err != nil {
+		pool.Close()
+		return nil, fmt.Errorf("store: ping: %w", err)
+	}
+	return &Store{Pool: pool}, nil
+}
+
+// Close gibt den Verbindungspool frei.
+func (s *Store) Close() {
+	s.Pool.Close()
+}
diff --git a/internal/store/store_test.go b/internal/store/store_test.go
new file mode 100644
index 0000000..10cdf0f
--- /dev/null
+++ b/internal/store/store_test.go
@@ -0,0 +1,86 @@
+package store_test
+
+import (
+	"context"
+	"os"
+	"testing"
+
+	"github.com/netcell-it/deklarix/internal/store"
+)
+
+// Diese Tests brauchen eine laufende Postgres-Instanz und werden ohne
+// DATABASE_URL übersprungen, statt eine Verbindung vorzutäuschen.
+func testDatabaseURL(t *testing.T) string {
+	t.Helper()
+	url := os.Getenv("DATABASE_URL")
+	if url == "" {
+		t.Skip("DATABASE_URL nicht gesetzt, überspringe Store-Integrationstest")
+	}
+	return url
+}
+
+func TestMigrateAndOpen(t *testing.T) {
+	url := testDatabaseURL(t)
+
+	if err := store.Migrate(url); err != nil {
+		t.Fatalf("Migrate: %v", err)
+	}
+
+	s, err := store.Open(context.Background(), url)
+	if err != nil {
+		t.Fatalf("Open: %v", err)
+	}
+	defer s.Close()
+
+	var tableCount int
+	err = s.Pool.QueryRow(context.Background(), `
+		SELECT count(*) FROM information_schema.tables
+		WHERE table_schema = 'public' AND table_name = ANY($1)
+	`, []string{"submission", "asset", "extraction", "finding", "evidence_package", "participant"}).Scan(&tableCount)
+	if err != nil {
+		t.Fatalf("query tables: %v", err)
+	}
+	if tableCount != 6 {
+		t.Fatalf("expected 6 tables, got %d", tableCount)
+	}
+}
+
+func TestFindingIsAppendOnly(t *testing.T) {
+	url := testDatabaseURL(t)
+
+	if err := store.Migrate(url); err != nil {
+		t.Fatalf("Migrate: %v", err)
+	}
+
+	s, err := store.Open(context.Background(), url)
+	if err != nil {
+		t.Fatalf("Open: %v", err)
+	}
+	defer s.Close()
+
+	ctx := context.Background()
+
+	var submissionID string
+	err = s.Pool.QueryRow(ctx, `
+		INSERT INTO submission (platform, post_type) VALUES ('instagram', 'reel')
+		RETURNING id
+	`).Scan(&submissionID)
+	if err != nil {
+		t.Fatalf("insert submission: %v", err)
+	}
+
+	var findingID string
+	err = s.Pool.QueryRow(ctx, `
+		INSERT INTO finding (submission_id, rule_id, rule_version, severity, message)
+		VALUES ($1, 'WK-004', 3, 'hoch', 'Testfeststellung')
+		RETURNING id
+	`, submissionID).Scan(&findingID)
+	if err != nil {
+		t.Fatalf("insert finding: %v", err)
+	}
+
+	_, err = s.Pool.Exec(ctx, `UPDATE finding SET message = 'geändert' WHERE id = $1`, findingID)
+	if err == nil {
+		t.Fatal("expected UPDATE on finding to be rejected, but it succeeded")
+	}
+}
diff --git a/scripts/test.sh b/scripts/test.sh
index 6a44740..8c55e1a 100755
--- a/scripts/test.sh
+++ b/scripts/test.sh
@@ -15,6 +15,36 @@ fail() { echo -e "${RED}[FAIL]${NC} $*"; exit 1; }
 
 cd "$REPO_DIR"
 
+# internal/store hat Integrationstests gegen echtes Postgres (u. a. die
+# Append-only-Garantie auf finding/extraction/evidence_package). Ohne
+# DATABASE_URL überspringt Go diese Tests still — das darf im
+# Release-Pfad (release.sh ruft dieses Skript auf) nicht passieren.
+# Deshalb hier immer ein Wegwerf-Postgres hochziehen.
+PG_CONTAINER="deklarix-test-pg-$$"
+PG_PORT=15432
+
+command -v docker >/dev/null 2>&1 || fail "docker wird für die Store-Tests (Postgres) benötigt"
+
+stop_test_db() { docker rm -f "$PG_CONTAINER" >/dev/null 2>&1 || true; }
+trap stop_test_db EXIT
+
+log "Starte Test-Postgres ($PG_CONTAINER) ..."
+docker run -d --name "$PG_CONTAINER" \
+    -e POSTGRES_PASSWORD=test -e POSTGRES_DB=deklarix \
+    -p "${PG_PORT}:5432" postgres:16-alpine >/dev/null
+
+ready=0
+for _ in $(seq 1 30); do
+    if docker exec "$PG_CONTAINER" pg_isready -U postgres >/dev/null 2>&1; then
+        ready=1
+        break
+    fi
+    sleep 1
+done
+[[ "$ready" -eq 1 ]] || fail "Test-Postgres wurde nicht rechtzeitig bereit"
+
+export DATABASE_URL="postgres://postgres:test@localhost:${PG_PORT}/deklarix?sslmode=disable"
+
 log "go vet ..."
 go vet ./... || fail "go vet fehlgeschlagen"