diff --git a/src/improv/api/app.py b/src/improv/api/app.py
index 9eda241..486b664 100644
--- a/src/improv/api/app.py
+++ b/src/improv/api/app.py
@@ -17,7 +17,8 @@ def create_app(config: "ImprovConfig") -> FastAPI:
     Registers service tables at startup via lifespan, injects ImageService
     via app.state for use in route dependencies.
     """
-    from amplify_db_utils import DuckDBParquetStore
+    from amplify_db_utils import DuckDBParquetStore, DuckDBParquetConfig
+    from amplify_db_utils.vastdb_store import VastDBConfig, VastDBStore
     from sqlalchemy import create_engine
     from sqlalchemy.orm import sessionmaker
 
@@ -28,7 +29,14 @@ def create_app(config: "ImprovConfig") -> FastAPI:
 
     @asynccontextmanager
     async def lifespan(app: FastAPI):
-        store = DuckDBParquetStore(config.db_config)
+        if isinstance(config.db_config, VastDBConfig):
+            store = VastDBStore(config.db_config)
+        elif isinstance(config.db_config, DuckDBParquetConfig):
+            store = DuckDBParquetStore(config.db_config)
+        else:
+            raise RuntimeError(
+                f"Unsupported db_config type: {type(config.db_config).__name__}"
+            )
         engine = create_engine(config.database_url or "sqlite:///:memory:")
         Base.metadata.create_all(engine)
         Session = sessionmaker(bind=engine)
diff --git a/src/improv/config.py b/src/improv/config.py
index 06451af..4de5b51 100644
--- a/src/improv/config.py
+++ b/src/improv/config.py
@@ -20,6 +20,7 @@
 from typing import TYPE_CHECKING
 
 from amplify_db_utils import DuckDBParquetConfig
+from amplify_db_utils.vastdb_store import VastDBConfig
 
 if TYPE_CHECKING:
     from improv.ids import ImageIdParser
@@ -30,7 +31,7 @@
 @dataclass
 class ImprovConfig:
     # Columnar store — required
-    db_config: DuckDBParquetConfig
+    db_config: DuckDBParquetConfig | VastDBConfig
 
     # OLTP database — required for service mode; omit for batch-producer use
     database_url: str | None = None
@@ -45,19 +46,28 @@ class ImprovConfig:
 
 def load_config() -> ImprovConfig:
     """Build ImprovConfig from environment variables."""
+    backend = os.environ.get("IMPROV_DB_BACKEND", "duckdb").lower()
     db_root = os.environ.get("IMPROV_DB_ROOT")
-    if not db_root:
-        raise RuntimeError(
-            "IMPROV_DB_ROOT environment variable is required. "
-            "Set it to a local path or s3:// URL."
+    
+    if backend == "vastdb":
+        db_cfg = VastDBConfig(
+            endpoint=os.environ["IMPROV_VASTDB_ENDPOINT"],
+            access_key=os.environ["IMPROV_VASTDB_ACCESS_KEY"],
+            secret_key=os.environ["IMPROV_VASTDB_SECRET_KEY"],
+            bucket=os.environ["IMPROV_VASTDB_BUCKET"],
+            schema=os.environ["IMPROV_VASTDB_SCHEMA"],
+            add_written_at=True,
+        )
+    elif backend == "duckdb":
+        db_root = os.environ.get("IMPROV_DB_ROOT")
+        if not db_root:
+            raise RuntimeError("IMPROV_DB_ROOT required for duckdb backend.")
+        db_cfg = DuckDBParquetConfig(
+            root=db_root,
+            s3_endpoint=os.environ.get("IMPROV_S3_ENDPOINT"),
+            s3_access_key=os.environ.get("IMPROV_S3_ACCESS_KEY"),
+            s3_secret_key=os.environ.get("IMPROV_S3_SECRET_KEY"),
         )
-
-    db_cfg = DuckDBParquetConfig(
-        root=db_root,
-        s3_endpoint=os.environ.get("IMPROV_S3_ENDPOINT"),
-        s3_access_key=os.environ.get("IMPROV_S3_ACCESS_KEY"),
-        s3_secret_key=os.environ.get("IMPROV_S3_SECRET_KEY"),
-    )
 
     storage = None
     storage_path = os.environ.get("IMPROV_STORAGE_PATH")
diff --git a/tests/conftest.py b/tests/conftest.py
index 5eef05d..b4fb536 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -16,6 +16,16 @@
 from improv.service import ImageService
 from improv.store.tables import register_service_tables
 
+import os
+import uuid
+import pytest
+
+from amplify_db_utils import DuckDBParquetConfig, DuckDBParquetStore
+from amplify_db_utils.vastdb_store import VastDBConfig, VastDBStore
+
+_BACKENDS = ["duckdb"]
+if os.environ.get("IMPROV_TEST_VASTDB") == "1":
+    _BACKENDS.append("vastdb")
 
 # ---------------------------------------------------------------------------
 # Synthetic parsers for tests — no real instrument format assumed
@@ -72,10 +82,27 @@ def parsers(alpha_parser, beta_parser) -> list:
 # Columnar store
 # ---------------------------------------------------------------------------
 
-@pytest.fixture
-def store(tmp_path):
-    config = DuckDBParquetConfig(root=str(tmp_path / "store"))
-    return DuckDBParquetStore(config)
+@pytest.fixture(params=_BACKENDS)
+def store(request, tmp_path):
+    if request.param == "duckdb":
+        cfg = DuckDBParquetConfig(root=str(tmp_path / "store"))
+        yield DuckDBParquetStore(cfg)
+        return
+
+    # VastDB: per-test unique schema for isolation, torn down after.
+    cfg = VastDBConfig(
+        endpoint=os.environ["IMPROV_TEST_VASTDB_ENDPOINT"],
+        access_key=os.environ["IMPROV_TEST_VASTDB_ACCESS_KEY"],
+        secret_key=os.environ["IMPROV_TEST_VASTDB_SECRET_KEY"],
+        bucket=os.environ["IMPROV_TEST_VASTDB_BUCKET"],
+        schema=f"improv_test_{uuid.uuid4().hex[:8]}",
+        add_written_at=True,
+    )
+    s = VastDBStore(cfg)
+    try:
+        yield s
+    finally:
+        s.drop_schema()
 
 
 @pytest.fixture