diff --git a/tests/Support/TestDb.php b/tests/Support/TestDb.php
new file mode 100644
index 00000000..7a0d2645
--- /dev/null
+++ b/tests/Support/TestDb.php
@@ -0,0 +1,132 @@
+<?php
+
+/**
+ * TestDb — in-memory SQLite test double for the XC_VM Database wrapper.
+ *
+ * Mirrors the subset of Database's public API used by repositories/services
+ * (query / get_rows / get_row / get_col / get_column / num_rows /
+ * last_insert_id / escape), but backed by `sqlite::memory:` so DB-touching
+ * code can be unit-tested without a MySQL server. Inject via the service's
+ * setDb() (the DI seam present on every domain repository/service).
+ *
+ * Usage:
+ *   $db = new TestDb();
+ *   $db->exec('CREATE TABLE ...; INSERT INTO ...;');
+ *   SomeRepository::setDb($db);
+ *
+ * Caveat: SQLite is NOT MySQL. Code using MySQL-specific SQL — `JSON_CONTAINS`,
+ * `information_schema`, MySQL-only functions — cannot be exercised here and
+ * needs a real MySQL (CI service) or a query-level mock instead.
+ *
+ * @package XC_VM_Tests_Support
+ */
+final class TestDb {
+
+	public PDO $pdo;
+
+	/** @var array<int,array<string,mixed>> Buffered rows from the last SELECT. */
+	private array $rows = [];
+
+	private int $lastInsertId = 0;
+
+	public function __construct(?PDO $pdo = null) {
+		$this->pdo = $pdo ?? new PDO('sqlite::memory:');
+		$this->pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
+	}
+
+	/**
+	 * Execute raw schema/seed SQL (one or more `;`-separated statements).
+	 */
+	public function exec(string $sql): void {
+		$this->pdo->exec($sql);
+	}
+
+	/**
+	 * Run a prepared query. Bind values follow $query (as in Database::query()).
+	 * SELECT/PRAGMA/WITH results are buffered for get_rows()/get_row()/num_rows().
+	 */
+	public function query($query, ...$args): bool {
+		// Mirror Database: the literal string 'null' and PHP null bind as SQL NULL.
+		$binds = array();
+		foreach ($args as $a) {
+			$binds[] = (is_string($a) && strtolower($a) === 'null') ? null : $a;
+		}
+
+		$stmt = $this->pdo->prepare($query);
+		$stmt->execute($binds);
+
+		if (preg_match('/^\s*(SELECT|PRAGMA|WITH)/i', $query)) {
+			$this->rows = $stmt->fetchAll(PDO::FETCH_ASSOC) ?: array();
+		} else {
+			$this->rows = array();
+			$id = $this->pdo->lastInsertId();
+			if ($id) {
+				$this->lastInsertId = (int) $id;
+			}
+		}
+
+		return true;
+	}
+
+	/**
+	 * Return buffered rows, optionally keyed by a column (mirrors Database).
+	 */
+	public function get_rows($use_id = false, $column_as_id = '', $unique_row = true, $sub_row_id = '') {
+		if (!$use_id) {
+			return $this->rows;
+		}
+
+		$out = array();
+		foreach ($this->rows as $row) {
+			if ($column_as_id !== '' && array_key_exists($column_as_id, $row)) {
+				if ($unique_row) {
+					$out[$row[$column_as_id]] = $row;
+				} elseif (!empty($sub_row_id) && array_key_exists($sub_row_id, $row)) {
+					$out[$row[$column_as_id]][$row[$sub_row_id]] = $row;
+				} else {
+					$out[$row[$column_as_id]][] = $row;
+				}
+			} else {
+				$out[] = $row;
+			}
+		}
+		return $out;
+	}
+
+	public function get_row() {
+		return $this->rows[0] ?? array();
+	}
+
+	public function get_col() {
+		$row = $this->rows[0] ?? null;
+		return $row ? array_values($row)[0] : false;
+	}
+
+	public function get_column(): array {
+		$col = array();
+		foreach ($this->rows as $row) {
+			$col[] = array_values($row)[0] ?? null;
+		}
+		return $col;
+	}
+
+	public function num_rows(): int {
+		return count($this->rows);
+	}
+
+	public function last_insert_id() {
+		return $this->lastInsertId;
+	}
+
+	public function escape($string) {
+		return $this->pdo->quote((string) $string);
+	}
+
+	public function close_mysql(): bool {
+		return true;
+	}
+
+	public function clean_row($row) {
+		return $row;
+	}
+}
diff --git a/tests/Unit/StreamConfigRepositoryTest.php b/tests/Unit/StreamConfigRepositoryTest.php
new file mode 100644
index 00000000..eb7ea528
--- /dev/null
+++ b/tests/Unit/StreamConfigRepositoryTest.php
@@ -0,0 +1,76 @@
+<?php
+
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Sample of the SQLite test harness: exercises a real repository against an
+ * in-memory database injected via setDb().
+ *
+ * @covers StreamConfigRepository
+ */
+final class StreamConfigRepositoryTest extends TestCase {
+
+	private TestDb $db;
+
+	protected function setUp(): void {
+		$this->db = new TestDb();
+		$this->db->exec(
+			'CREATE TABLE profiles (profile_id INTEGER PRIMARY KEY, profile_name TEXT);
+			 CREATE TABLE streams (id INTEGER PRIMARY KEY, transcode_profile_id INTEGER DEFAULT 0);
+			 CREATE TABLE watch_folders (id INTEGER PRIMARY KEY, transcode_profile_id INTEGER DEFAULT 0);
+			 CREATE TABLE streams_arguments (id INTEGER PRIMARY KEY, argument_key TEXT, argument_cmd TEXT);
+
+			 INSERT INTO profiles (profile_id, profile_name) VALUES (1, "CPU"), (2, "GPU");
+			 INSERT INTO streams (id, transcode_profile_id) VALUES (10, 2), (11, 1);
+			 INSERT INTO watch_folders (id, transcode_profile_id) VALUES (5, 2);
+			 INSERT INTO streams_arguments (id, argument_key, argument_cmd) VALUES
+			   (1, "cookie", "-headers ?"), (2, "useragent", "-user_agent ?");'
+		);
+
+		StreamConfigRepository::setDb($this->db);
+	}
+
+	public function testGetTranscodeProfilesReturnsAll() {
+		$profiles = StreamConfigRepository::getTranscodeProfiles();
+		$this->assertCount(2, $profiles);
+		$this->assertSame('CPU', $profiles[0]['profile_name']);
+	}
+
+	public function testGetTranscodeProfileByIdReturnsRow() {
+		$profile = StreamConfigRepository::getTranscodeProfile(2);
+		$this->assertIsArray($profile);
+		$this->assertSame('GPU', $profile['profile_name']);
+	}
+
+	public function testGetTranscodeProfileReturnsNullWhenMissing() {
+		$this->assertNull(StreamConfigRepository::getTranscodeProfile(999));
+	}
+
+	public function testGetStreamArgumentsKeyedByArgumentKey() {
+		$args = StreamConfigRepository::getStreamArguments();
+		$this->assertArrayHasKey('cookie', $args);
+		$this->assertArrayHasKey('useragent', $args);
+		$this->assertSame('-user_agent ?', $args['useragent']['argument_cmd']);
+	}
+
+	public function testDeleteProfileRemovesRowAndDetachesReferences() {
+		$this->assertTrue(StreamConfigRepository::deleteProfile(2));
+
+		// Profile gone.
+		$this->assertNull(StreamConfigRepository::getTranscodeProfile(2));
+
+		// References reset to 0; the unrelated stream keeps its profile.
+		$this->db->query('SELECT transcode_profile_id FROM streams WHERE id = ?;', 10);
+		$this->assertSame(0, (int) $this->db->get_col());
+
+		$this->db->query('SELECT transcode_profile_id FROM streams WHERE id = ?;', 11);
+		$this->assertSame(1, (int) $this->db->get_col());
+
+		$this->db->query('SELECT transcode_profile_id FROM watch_folders WHERE id = ?;', 5);
+		$this->assertSame(0, (int) $this->db->get_col());
+	}
+
+	public function testDeleteProfileReturnsFalseWhenMissing() {
+		$this->assertFalse(StreamConfigRepository::deleteProfile(999));
+	}
+}
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index 9059917b..5d7aca33 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -72,3 +72,6 @@ require_once MAIN_HOME . 'autoload.php';
 require_once MAIN_HOME . 'core/Parsing/M3uParser/bootstrap.php';
 require_once MAIN_HOME . 'core/Parsing/PhpM3u8/bootstrap.php';
 require_once __DIR__ . '/Unit/M3uParser/ExtCustomTag.php';
+
+// Test support: in-memory SQLite harness for DB-touching repositories/services.
+require_once __DIR__ . '/Support/TestDb.php';