feat(migrate-ts): emit CHECK constraints for postgres (create-table + alter)

Postgres: inline CONSTRAINT ... CHECK in CREATE TABLE; add-check/drop-check
emit ALTER TABLE ADD/DROP CONSTRAINT with inverse down statements.

Exhaustiveness (Change kind is a closed union): add add-check/drop-check arms
to the sqlite emit switches (STAGE_ORDER + changeTable + renderUpNative/
renderDownNative throw "CHECK migration not implemented for sqlite (recreate
path pending)" rather than mis-emit) and to errors.ts changeLocator.

Defensive: diff + create-table emit tolerate an absent `checks` array (?? [])
so older snapshots / hand-built fixtures don't crash — mirrors the v1->v2
parse upgrade that defaults absent checks to [].

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: dmealing

server/typescript/packages/migrate-ts/src/diff/index.ts

@@ -129,7 +129,7 @@ export async function diff(
           fk, status: ALLOWED,
         });
       }
-      for (const check of table.checks) {
+      for (const check of table.checks ?? []) {
         changes.push({
           kind: "add-check", table: table.name, ...schemaSpread(table.schema),
           check, status: ALLOWED,
@@ -269,8 +269,10 @@ function diffTableChecks(
 ): void {
   const table = expected.name;
   const sx = schemaSpread(expected.schema);
-  const expectedChk = new Map(expected.checks.map((c) => [c.name, c]));
-  const actualChk = new Map(actual.checks.map((c) => [c.name, c]));
+  // Tolerate a missing `checks` array (older snapshots / hand-built fixtures);
+  // mirrors the v1→v2 parse upgrade that defaults absent checks to [].
+  const expectedChk = new Map((expected.checks ?? []).map((c) => [c.name, c]));
+  const actualChk = new Map((actual.checks ?? []).map((c) => [c.name, c]));
   for (const [name, ec] of expectedChk) {
     const ac = actualChk.get(name);
     if (!ac) {

server/typescript/packages/migrate-ts/src/emit/postgres.ts

@@ -16,6 +16,7 @@ const STAGE_ORDER: Record<Change["kind"], number> = {
   "rename-column": 3, "rename-table": 3,
   "add-index": 4, "drop-index": 4,
   "add-fk": 5, "drop-fk": 5,
+  "add-check": 5, "drop-check": 5,
   "drop-table": 6,
   "create-view": 7, "replace-view": 7,
 };
@@ -61,6 +62,8 @@ function renderUp(c: Change): string {
     case "drop-index":             return `DROP INDEX ${quoteIndexQualified(c.index, c.schema)};`;
     case "add-fk":                 return renderAddFk(c.table, c.schema, c.fk);
     case "drop-fk":                return `ALTER TABLE ${quoteQualified(c.table, c.schema)} DROP CONSTRAINT ${quote(c.fk)};`;
+    case "add-check":              return `ALTER TABLE ${quoteQualified(c.table, c.schema)} ADD CONSTRAINT ${quote(c.check.name)} CHECK (${c.check.expression});`;
+    case "drop-check":             return `ALTER TABLE ${quoteQualified(c.table, c.schema)} DROP CONSTRAINT ${quote(c.check)};`;
     case "create-view":            return renderCreateView(c.view, c.schema, /* orReplace */ false);
     case "drop-view":              return `DROP VIEW ${quoteQualifiedView(c.view, c.schema)};`;
     case "replace-view":           return renderCreateView(c.view, c.schema, /* orReplace */ true);
@@ -88,6 +91,8 @@ function renderDown(c: Change): string {
     case "drop-index":             return `-- WARNING: down migration cannot restore the original index definition`;
     case "add-fk":                 return `ALTER TABLE ${quoteQualified(c.table, c.schema)} DROP CONSTRAINT ${quote(c.fk.name)};`;
     case "drop-fk":                return `-- WARNING: down migration cannot restore the original FK definition`;
+    case "add-check":              return `ALTER TABLE ${quoteQualified(c.table, c.schema)} DROP CONSTRAINT ${quote(c.check.name)};`;
+    case "drop-check":             return `-- WARNING: down migration cannot restore the original CHECK definition`;
     case "create-view":            return `DROP VIEW ${quoteQualifiedView(c.view.name, c.schema)};`;
     case "drop-view":              return `-- WARNING: down migration cannot restore the original view definition`;
     case "replace-view":           return `-- WARNING: down migration cannot restore the original view definition`;
@@ -99,6 +104,9 @@ function renderCreateTable(t: TableDescriptor): string {
   if (t.primaryKey.length > 0) {
     colDefs.push(`  CONSTRAINT ${quote(t.name + "_pkey")} PRIMARY KEY (${t.primaryKey.map(quote).join(", ")})`);
   }
+  for (const chk of t.checks ?? []) {
+    colDefs.push(`  CONSTRAINT ${quote(chk.name)} CHECK (${chk.expression})`);
+  }
   const create = `CREATE TABLE ${quoteQualified(t.name, t.schema)} (\n${colDefs.join(",\n")}\n);`;
   const comments = renderTableComments(t);
   return comments.length === 0 ? create : `${create}\n${comments.join("\n")}`;

server/typescript/packages/migrate-ts/src/emit/sqlite.ts

@@ -13,6 +13,7 @@ const STAGE_ORDER: Record<Change["kind"], number> = {
   "rename-column": 3, "rename-table": 3,
   "add-index": 4, "drop-index": 4,
   "add-fk": 5, "drop-fk": 5,
+  "add-check": 5, "drop-check": 5,
   "drop-table": 6,
   "create-view": 99, "drop-view": 99, "replace-view": 99,
 };
@@ -110,6 +111,8 @@ function changeTable(c: Change): string | undefined {
     case "drop-index":
     case "add-fk":
     case "drop-fk":
+    case "add-check":
+    case "drop-check":
       return c.table;
     default:
       return undefined;
@@ -188,6 +191,11 @@ function renderUpNative(c: Change): string {
     case "rename-column":  return `ALTER TABLE ${quote(c.table)} RENAME COLUMN ${quote(c.from)} TO ${quote(c.to)};`;
     case "add-index":      return renderCreateIndex(c.table, c.index);
     case "drop-index":     return `DROP INDEX ${quote(c.index)};`;
+    case "add-check":
+    case "drop-check":
+      // SQLite cannot ADD/DROP a CHECK in place; it needs the recreate-and-copy
+      // machinery (a follow-on). Throw rather than silently mis-emit.
+      throw new Error("CHECK migration not implemented for sqlite (recreate path pending)");
     case "change-column-type":
     case "change-column-nullable":
     case "change-column-default":
@@ -212,6 +220,11 @@ function renderDownNative(c: Change): string {
     case "rename-column":  return `ALTER TABLE ${quote(c.table)} RENAME COLUMN ${quote(c.to)} TO ${quote(c.from)};`;
     case "add-index":      return `DROP INDEX ${quote(c.index.name)};`;
     case "drop-index":     return `-- WARNING: down migration cannot restore the original index definition`;
+    case "add-check":
+    case "drop-check":
+      // SQLite cannot ADD/DROP a CHECK in place; it needs the recreate-and-copy
+      // machinery (a follow-on). Throw rather than silently mis-emit.
+      throw new Error("CHECK migration not implemented for sqlite (recreate path pending)");
     case "change-column-type":
     case "change-column-nullable":
     case "change-column-default":

server/typescript/packages/migrate-ts/src/errors.ts

@@ -65,6 +65,10 @@ function changeLocator(c: Change): string {
       return `${c.table}.${c.fk.name}`;
     case "drop-fk":
       return `${c.table}.${c.fk}`;
+    case "add-check":
+      return `${c.table}.${c.check.name}`;
+    case "drop-check":
+      return `${c.table}.${c.check}`;
     case "create-view":
     case "replace-view":
       return c.view.name;

server/typescript/packages/migrate-ts/test/check/emit-postgres-check.test.ts

@@ -0,0 +1,27 @@
+// test/check/emit-postgres-check.test.ts
+import { describe, test, expect } from "bun:test";
+import type { TableDescriptor, Change } from "../../src/types.js";
+import { emit } from "../../src/emit/index.js";
+
+const ALLOWED = { state: "ok" } as const;
+const CHK = { name: "orders_status_chk", expression: "status IN ('OPEN','CLOSED')" };
+const table: TableDescriptor = {
+  name: "orders", columns: [{ name: "status", sqlType: { kind: "text" }, nullable: false }],
+  indexes: [], foreignKeys: [], primaryKey: [], checks: [CHK],
+};
+
+describe("emit postgres — checks", () => {
+  test("create-table inlines the CHECK constraint", () => {
+    const r = emit([{ kind: "create-table", table, status: ALLOWED } as unknown as Change], { dialect: "postgres" });
+    expect(r.up).toContain(`CONSTRAINT "orders_status_chk" CHECK (status IN ('OPEN','CLOSED'))`);
+  });
+  test("add-check → ALTER TABLE ADD CONSTRAINT; down drops it", () => {
+    const r = emit([{ kind: "add-check", table: "orders", check: CHK, status: ALLOWED } as unknown as Change], { dialect: "postgres" });
+    expect(r.up).toContain(`ALTER TABLE "orders" ADD CONSTRAINT "orders_status_chk" CHECK (status IN ('OPEN','CLOSED'));`);
+    expect(r.down).toContain(`ALTER TABLE "orders" DROP CONSTRAINT "orders_status_chk";`);
+  });
+  test("drop-check → ALTER TABLE DROP CONSTRAINT", () => {
+    const r = emit([{ kind: "drop-check", table: "orders", check: "orders_status_chk", status: ALLOWED } as unknown as Change], { dialect: "postgres" });
+    expect(r.up).toContain(`ALTER TABLE "orders" DROP CONSTRAINT "orders_status_chk";`);
+  });
+});