feat(sql-fs): fence stale sandbox writers with durable epochs

src/api/tests/integration/migrations.integration.test.ts

@@ -58,7 +58,7 @@ describe.skipIf(SKIP)("runMigrations (integration)", () => {
 		}
 	});
 
-	it("applies migrations to an empty database and second run is a no-op", async () => {
+	it("applies migrations to an empty database and second run preserves epoch state", async () => {
 		const cfg = loadTenantConfig({
 			TENANT_DATABASES: JSON.stringify({ default: testUrl }),
 		});
@@ -79,10 +79,70 @@ describe.skipIf(SKIP)("runMigrations (integration)", () => {
 				WHERE n.nspname = 'public' AND p.proname = 'fs_resolve'
 			`;
 			expect(Number(procs[0]?.n)).toBeGreaterThanOrEqual(1);
+
+			const versionColumn = await sql<{ data_type: string; is_nullable: string; column_default: string | null }[]>`
+				SELECT data_type, is_nullable, column_default
+				FROM information_schema.columns
+				WHERE table_schema = 'public' AND table_name = 'sandboxes' AND column_name = 'version'
+			`;
+			expect(versionColumn).toEqual([{ data_type: "bigint", is_nullable: "NO", column_default: "0" }]);
+
+			const epochColumns = await sql<
+				{ column_name: string; data_type: string; is_nullable: string; column_default: string | null }[]
+			>`
+				SELECT column_name, data_type, is_nullable, column_default
+				FROM information_schema.columns
+				WHERE table_schema = 'public' AND table_name = 'sandbox_epochs'
+				ORDER BY ordinal_position
+			`;
+			expect(epochColumns).toEqual([
+				{ column_name: "sandbox_id", data_type: "text", is_nullable: "NO", column_default: null },
+				{ column_name: "epoch", data_type: "bigint", is_nullable: "NO", column_default: "0" },
+				{
+					column_name: "deleted_at",
+					data_type: "timestamp with time zone",
+					is_nullable: "NO",
+					column_default: "now()",
+				},
+			]);
+
+			const sandboxId = "migration-epoch-sandbox";
+			await sql`INSERT INTO sandboxes (id, root_inode) VALUES (${sandboxId}, NULL)`;
+			const initial = await sql<{ version: string }[]>`
+				SELECT version::text FROM sandboxes WHERE id = ${sandboxId}
+			`;
+			expect(initial[0]?.version).toBe("0");
+
+			await sql`
+				INSERT INTO sandbox_epochs (sandbox_id, epoch)
+				VALUES (${sandboxId}, 1)
+			`;
+			await sql`DELETE FROM sandboxes WHERE id = ${sandboxId}`;
+			const tombstone = await sql<{ sandbox_id: string; epoch: string }[]>`
+				SELECT sandbox_id, epoch::text FROM sandbox_epochs WHERE sandbox_id = ${sandboxId}
+			`;
+			expect(tombstone).toEqual([{ sandbox_id: sandboxId, epoch: "1" }]);
 		} finally {
 			await sql.end({ timeout: 5 });
 		}
 
 		await expect(runMigrations(cfg)).resolves.toBeUndefined();
-	});
+
+		const afterRerun = postgres(testUrl, { prepare: false, max: 1 });
+		try {
+			const versionColumn = await afterRerun<{ data_type: string; is_nullable: string }[]>`
+				SELECT data_type, is_nullable
+				FROM information_schema.columns
+				WHERE table_schema = 'public' AND table_name = 'sandboxes' AND column_name = 'version'
+			`;
+			expect(versionColumn).toEqual([{ data_type: "bigint", is_nullable: "NO" }]);
+
+			const tombstone = await afterRerun<{ epoch: string }[]>`
+				SELECT epoch::text FROM sandbox_epochs WHERE sandbox_id = 'migration-epoch-sandbox'
+			`;
+			expect(tombstone).toEqual([{ epoch: "1" }]);
+		} finally {
+			await afterRerun.end({ timeout: 5 });
+		}
+	}, 60_000);
 });