diff --git a/.gitignore b/.gitignore
index 0e79824..266baaf 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,7 @@ target/
 project/target/
 project/project/
 .version
+
+# the test directory is used when running tests as an ephemeral dumping ground
+test/*
+!test/README.md
diff --git a/build.sbt b/build.sbt
index 782d547..c816889 100644
--- a/build.sbt
+++ b/build.sbt
@@ -55,12 +55,17 @@ val Deps = new {
   }
 
   val MUnit: ModuleID = "org.scalameta" %% "munit" % "1.2.1"
+
+  val Slf4j = new {
+    val Nop: ModuleID = "org.slf4j" % "slf4j-nop" % "2.0.17"
+  }
 }
 
 lazy val testSettings = Seq(
   libraryDependencies ++= Seq(
     Deps.MUnit      % Test,
-    Deps.Gs.Datagen % Test
+    Deps.Gs.Datagen % Test,
+    Deps.Slf4j.Nop  % Test
   )
 )
 
diff --git a/modules/db/src/main/scala/gs/smolban/db/doobie/CuratedSqlStates.scala b/modules/db/src/main/scala/gs/smolban/db/doobie/CuratedSqlStates.scala
index bc697df..f305894 100644
--- a/modules/db/src/main/scala/gs/smolban/db/doobie/CuratedSqlStates.scala
+++ b/modules/db/src/main/scala/gs/smolban/db/doobie/CuratedSqlStates.scala
@@ -2,16 +2,26 @@ package gs.smolban.db.doobie
 
 import doobie.enumerated.SqlState
 
+/** Used to support semantic SQL states (for error handling) across database
+  * implementations. Smolban supports both SQLite and PostgreSQL.
+  */
 sealed trait CuratedSqlStates:
   def uniqueViolation: SqlState
 
 object CuratedSqlStates:
 
+  lazy val postgres: CuratedSqlStates = new PostgreSQL
+  lazy val sqlite: CuratedSqlStates   = new Sqlite
+
+  /** Should be injected when Smolban is run using PostgreSQL.
+    */
   final class PostgreSQL extends CuratedSqlStates:
 
     override val uniqueViolation: SqlState =
       doobie.postgres.sqlstate.class23.UNIQUE_VIOLATION
 
+  /** Should be injected when Smolban is run using SQLite.
+    */
   final class Sqlite extends CuratedSqlStates:
 
     override val uniqueViolation: SqlState =
diff --git a/modules/db/src/main/scala/gs/smolban/db/doobie/DoobieTagDb.scala b/modules/db/src/main/scala/gs/smolban/db/doobie/DoobieTagDb.scala
index 0900f90..c00ba51 100644
--- a/modules/db/src/main/scala/gs/smolban/db/doobie/DoobieTagDb.scala
+++ b/modules/db/src/main/scala/gs/smolban/db/doobie/DoobieTagDb.scala
@@ -52,18 +52,18 @@ object DoobieTagDb:
       tag: TagValue,
       createdAt: CreatedAt
     ): Update0 = sql"""
-    INSERT INTO tags (tag_value, created_at)
+    INSERT INTO tag (tag_value, created_at)
     VALUES ($tag, $createdAt)
     """.update
 
     def readTag(tag: TagValue): Query0[Tag] = sql"""
     SELECT tag_value, created_at
-    FROM tags
+    FROM tag
     WHERE tag_value = $tag
     """.query[Tag]
 
     def deleteTag(tag: TagValue): Update0 = sql"""
-    DELETE FROM tags
+    DELETE FROM tag
     WHERE tag_value = $tag
     """.update
 
diff --git a/modules/db/src/test/scala/gs/smolban/db/doobie/DoobieTagDbTests.scala b/modules/db/src/test/scala/gs/smolban/db/doobie/DoobieTagDbTests.scala
new file mode 100644
index 0000000..8f16ddb
--- /dev/null
+++ b/modules/db/src/test/scala/gs/smolban/db/doobie/DoobieTagDbTests.scala
@@ -0,0 +1,74 @@
+package gs.smolban.db.doobie
+
+import cats.effect.IO
+import cats.effect.Resource
+import cats.effect.unsafe.IORuntime
+import doobie.*
+import doobie.hikari.Config
+import doobie.hikari.HikariTransactor
+import doobie.implicits.*
+import doobie.util.transactor.Transactor
+import gs.smolban.db.TagDb
+import gs.smolban.model.metadata.CreatedAt
+import gs.smolban.model.metadata.Tag
+import gs.smolban.model.metadata.TagValue
+import java.time.Clock
+import munit.Location
+
+class DoobieTagDbTests extends munit.FunSuite:
+  given IORuntime = IORuntime.global
+
+  def iotest(
+    name: String
+  )(
+    f: => IO[Unit]
+  )(
+    using
+    Location
+  ): Unit =
+    test(name)(f.unsafeRunSync())
+
+  private val dbConfig: Config = Config(
+    jdbcUrl = "jdbc:sqlite:test/doobie_tag_db_tests",
+    driverClassName = Some("org.sqlite.JDBC")
+  )
+
+  private val transactor: Resource[IO, Transactor[IO]] =
+    HikariTransactor.fromConfig[IO](dbConfig)
+
+  private val tagDb: TagDb[ConnectionIO] = new DoobieTagDb(
+    CuratedSqlStates.sqlite
+  )
+
+  private val clock = Clock.systemDefaultZone()
+
+  iotest("should create, read, and delete a tag") {
+    val tagValue  = TagValue.validate("x").get
+    val createdAt = CreatedAt.now(clock)
+    transactor.use { xa =>
+      (for
+        _      <- dropTable().run
+        _      <- createTable().run
+        tag    <- tagDb.createTag(tagValue, createdAt).value
+        t2     <- tagDb.readTag(tagValue)
+        result <- tagDb.deleteTag(tagValue)
+      yield
+        assertEquals(tag, Right(Tag(tagValue, createdAt)))
+        assertEquals(t2, tag.toOption)
+        assert(result)
+      ).transact(xa)
+    }
+  }
+
+  def dropTable(): Update0 =
+    sql"""
+    DROP TABLE IF EXISTS tag
+    """.update
+
+  def createTable(): Update0 =
+    sql"""
+    CREATE TABLE IF NOT EXISTS tag(
+      tag_value TEXT NOT NULL PRIMARY KEY,
+      created_at DATETIME NOT NULL
+    )
+    """.update
diff --git a/modules/model/src/main/scala/gs/smolban/model/metadata/CreatedAt.scala b/modules/model/src/main/scala/gs/smolban/model/metadata/CreatedAt.scala
index 998536e..741bd9d 100644
--- a/modules/model/src/main/scala/gs/smolban/model/metadata/CreatedAt.scala
+++ b/modules/model/src/main/scala/gs/smolban/model/metadata/CreatedAt.scala
@@ -3,9 +3,13 @@ package gs.smolban.model.metadata
 import cats.Show
 import java.time.Clock
 import java.time.Instant
+import java.time.temporal.ChronoUnit
 
 /** Describes an instant at which something was created. Opaque type for
   * `java.time.Instant`.
+  *
+  * This type always truncates to milliseconds. This is the lowest common
+  * denominator for database representations (SQLite).
   */
 opaque type CreatedAt = Instant
 
@@ -18,7 +22,8 @@ object CreatedAt:
     * @return
     *   The new instance.
     */
-  def apply(timestamp: Instant): CreatedAt = timestamp
+  def apply(timestamp: Instant): CreatedAt =
+    timestamp.truncatedTo(ChronoUnit.MILLIS)
 
   /** Instantiate a new [[CreatedAt]] representing the current instant.
     *
@@ -27,7 +32,7 @@ object CreatedAt:
     * @return
     *   The new [[CreatedAt]] instance.
     */
-  def now(clock: Clock): CreatedAt = clock.instant()
+  def now(clock: Clock): CreatedAt = apply(clock.instant())
 
   /** Instantiate a new [[CreatedAt]].
     *
diff --git a/test/README.md b/test/README.md
new file mode 100644
index 0000000..56d968d
--- /dev/null
+++ b/test/README.md
@@ -0,0 +1,6 @@
+# Test Data
+
+This directory provides a dumping ground for test data that is produced by tests
+while running -- for example, SQLite databases.
+
+All files (aside from this file) in this directory are ignored.