diff --git a/src/resources/extensions/sf/sf-db/sf-db-core.js b/src/resources/extensions/sf/sf-db/sf-db-core.js
index 4c4decfe7..64fbb2359 100644
--- a/src/resources/extensions/sf/sf-db/sf-db-core.js
+++ b/src/resources/extensions/sf/sf-db/sf-db-core.js
@@ -23,6 +23,8 @@ import {
 	mkdirSync,
 	readdirSync,
 	readFileSync,
+	renameSync,
+	rmSync,
 	statSync,
 	unlinkSync,
 	writeFileSync,
@@ -199,13 +201,25 @@ function createDatabaseSnapshot(rawDb, path) {
 		if (latest > 0 && Date.now() - latest < DB_BACKUP_MIN_INTERVAL_MS) return;
 		const stamp = new Date().toISOString().replace(/[:.]/g, "-");
 		const backupPath = join(dir, `sf.db.${stamp}`);
-		rawDb.exec(`VACUUM INTO ${sqliteStringLiteral(backupPath)}`);
+		const tmpPath = `${backupPath}.tmp`;
+		rmSync(tmpPath, { force: true });
+		rawDb.exec(`VACUUM INTO ${sqliteStringLiteral(tmpPath)}`);
+		renameSync(tmpPath, backupPath);
 		pruneDatabaseBackups(dir);
 	} catch (err) {
 		logWarning(
 			"sf-db",
 			`database snapshot failed: ${getErrorMessage(err)}`,
 		);
+		try {
+			for (const entry of readdirSync(dir)) {
+				if (entry.startsWith("sf.db.") && entry.endsWith(".tmp")) {
+					rmSync(join(dir, entry), { force: true });
+				}
+			}
+		} catch {
+			// Best-effort cleanup; preserve the original snapshot warning.
+		}
 	}
 }
 function performDatabaseMaintenance(rawDb, path) {
diff --git a/src/resources/extensions/sf/tests/sf-db-migration.test.mjs b/src/resources/extensions/sf/tests/sf-db-migration.test.mjs
index 0392a9a85..942b25692 100644
--- a/src/resources/extensions/sf/tests/sf-db-migration.test.mjs
+++ b/src/resources/extensions/sf/tests/sf-db-migration.test.mjs
@@ -11,6 +11,7 @@ import {
 	mkdtempSync,
 	readdirSync,
 	rmSync,
+	statSync,
 } from "node:fs";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
@@ -453,6 +454,8 @@ test("openDatabase_when_file_backed_creates_db_snapshot_and_maintenance_marker",
 		name.startsWith("sf.db."),
 	);
 	assert.equal(backups.length, 1);
+	assert.equal(backups[0].endsWith(".tmp"), false);
+	assert.equal(statSync(join(backupDir, backups[0])).size > 0, true);
 	assert.equal(existsSync(join(backupDir, "maintenance.json")), true);
 });