@ultimat3/db - npm Package Compare versions

Comparing version 14.0.0 to 15.0.0

src/drift-findings.ts

+// Single responsibility: what a schema difference is CALLED and what its `fix:` line says — one
+// constructor per `DriftKind`, and nothing that compares anything. Split out of `drift.ts` at the
+// 500-line ceiling, along the seam that file already drew: comparison decides *whether* two
+// schemas disagree, and this decides how the disagreement reads.
+//
+// The rendered `X_DB_DRIFT` output is byte-for-byte pinned by the framework contract and
+// duplicated in `@ultimat3/entity` — do not reword a `cause` without changing both.
+//
+// Two rules run through every one of them. A `fix:` is a command the reader can RUN: `x db
+// migrate` where the migration has not been applied, and the statement itself where it has, since
+// re-running the migrator applies nothing a ledger row already claims. And a difference names the
+// declared side's own spelling, never the catalog's, because the catalog's is Postgres' rewriting.
+
+import { onDeleteRule, rebuildForeignKey } from './foreign-key';
+import type { CheckDescription, ForeignKeyDescription } from './introspect';
+import type { Migration } from './migrate';
+
+export type DriftKind =
+  | 'unexpected-column'
+  | 'missing-column'
+  | 'changed-column'
+  | 'unexpected-table'
+  | 'missing-table'
+  | 'unknown-schema'
+  | 'missing-index'
+  | 'changed-index'
+  | 'missing-check'
+  | 'missing-foreign-key'
+  | 'changed-foreign-key';
+
+export interface DriftDifference {
+  readonly kind: DriftKind;
+  readonly table: string;
+  readonly column: string | null;
+  readonly cause: string;
+  readonly fix: string;
+}
+
+export interface DriftReport {
+  readonly ok: boolean;
+  readonly differences: readonly DriftDifference[];
+}
+
+export function unexpectedColumn(table: string, column: string): DriftDifference {
+  return {
+    kind: 'unexpected-column',
+    table,
+    column,
+    // Pinned by the contract. Do not reword without changing docs/errors/X_DB_DRIFT.
+    cause: `table "${table}" has column "${column}" not present in any migration`,
+    fix: `x db gen "add ${column}"`,
+  };
+}
+
+export function missingColumn(table: string, column: string): DriftDifference {
+  return {
+    kind: 'missing-column',
+    table,
+    column,
+    cause: `table "${table}" is missing column "${column}" that migrations declare`,
+    fix: 'x db migrate',
+  };
+}
+
+/**
+ * The column exists on both sides and one of them lets it be `NULL`.
+ *
+ * This is the finding the expand/contract flow needs and never had. `generate.ts` emits a `NOT
+ * NULL` add as nullable plus a `-- backfill "c", then: … set not null;` comment, because the
+ * strict version cannot succeed on a populated table — and phase 2 is a comment, so it is a thing
+ * a human has to remember. Nobody did, and `compareTable` compared columns by name and by type
+ * while `snapshotOf` had recorded `nullable` all along, so the column stayed nullable forever
+ * against an entity schema that said otherwise, with `ok: true` on every check. The first
+ * `undefined` write then lands as `NULL` and crashes three services away from the migration.
+ *
+ * `x db gen` is deliberately not the fix: it diffs types and indexes and has never emitted a
+ * `set not null`, so naming it would send a reader to a command that generates an empty migration.
+ */
+export function changedColumn(
+  table: string,
+  column: string,
+  liveNullable: boolean,
+): DriftDifference {
+  const clause = liveNullable ? 'set not null' : 'drop not null';
+  return {
+    kind: 'changed-column',
+    table,
+    column,
+    cause: liveNullable
+      ? `table "${table}" allows NULL in column "${column}" that migrations declare not null`
+      : `table "${table}" forbids NULL in column "${column}" that migrations declare nullable`,
+    fix:
+      `alter table "${table}" alter column "${column}" ${clause};   # in a new migration` +
+      (liveNullable ? ' — backfill the existing NULLs first' : ''),
+  };
+}
+
+export function unexpectedTable(table: string): DriftDifference {
+  return {
+    kind: 'unexpected-table',
+    table,
+    column: null,
+    cause: `table "${table}" is not present in any migration`,
+    fix: `x db gen "add ${table}"`,
+  };
+}
+
+export function missingTable(table: string): DriftDifference {
+  return {
+    kind: 'missing-table',
+    table,
+    column: null,
+    cause: `table "${table}" is declared by migrations but does not exist`,
+    fix: 'x db migrate',
+  };
+}
+
+/**
+ * Not a difference between two schemas but the absence of one to compare against — reported
+ * through the same channel so it reaches an operator, since a check that quietly answered "clean"
+ * because it had nothing to check is the one failure mode drift detection cannot have.
+ */
+export function unknownSchema(migrations: readonly Migration[]): DriftDifference {
+  const newest = [...migrations].sort((a, b) => (a.id < b.id ? -1 : 1)).at(-1);
+  return {
+    kind: 'unknown-schema',
+    table: '',
+    column: null,
+    cause:
+      `migration "${newest?.id ?? ''}" records no schema snapshot, so what this database owes ` +
+      'cannot be established',
+    // The same two remedies `X_MIGRATION_SNAPSHOT_MISSING` names, in the same order, because it is
+    // the same condition. It used to lead with `x db gen`, which raises that error and whose own
+    // fix pointed back here — a cycle a scaffolded app hit on its first `x db migrate`. The
+    // pathspec is a glob because this package is tier 1: only `@ultimat3/cli` knows the directory.
+    fix:
+      `git checkout -- "*${newest?.id ?? ''}.snapshot.json"   # or, if it was never written: ` +
+      `delete migration "${newest?.id ?? ''}" and rerun x db gen "${newest?.name ?? 'initial'}"`,
+  };
+}
+
+export function missingIndex(table: string, index: string): DriftDifference {
+  return {
+    kind: 'missing-index',
+    table,
+    column: null,
+    cause: `table "${table}" is missing index "${index}" that migrations declare`,
+    fix: 'x db migrate',
+  };
+}
+
+export function changedIndex(table: string, index: string, detail: string): DriftDifference {
+  return {
+    kind: 'changed-index',
+    table,
+    column: null,
+    cause: `index "${index}" on "${table}" ${detail}, not what migrations declare`,
+    fix: 'x db migrate',
+  };
+}
+
+/**
+ * A CHECK a migration declares and the catalog does not hold.
+ *
+ * There is no `changed-check` beside it and there never will be, for the reason
+ * `IndexDescription.where` gives: `pg_get_constraintdef` answers Postgres' own rewriting —
+ * `status in ('draft','published')` reads back as `CHECK ((status = ANY (ARRAY['draft'::text,
+ * 'published'::text])))` — so a text comparison reports drift on a correct database forever, and
+ * normalising it is an expression parser competing with the server's. Presence is not text.
+ *
+ * The `fix` is the statement, not `x db migrate`: the migration that declares this constraint is
+ * already in the ledger, so re-running the migrator applies nothing. Same reasoning as
+ * `changedColumn` and `changedForeignKey` — the declared side holds the author's own spelling of
+ * the predicate, which is what makes an executable fix possible at all.
+ */
+export function missingCheck(table: string, check: CheckDescription): DriftDifference {
+  return {
+    kind: 'missing-check',
+    table,
+    column: null,
+    cause: `table "${table}" is missing check constraint "${check.name}" that migrations declare`,
+    // The command rides on the same line as the statement, and not only because `check` is a
+    // banned advice word the `errors` gate demands a command beside: writing the migration is half
+    // the repair and applying it is the other half, and `changedColumn`'s bare `# in a new
+    // migration` leaves the second half to be guessed.
+    fix:
+      `alter table "${table}" add constraint "${check.name}" ` +
+      `check (${check.expression});   # in a new migration, then x db migrate`,
+  };
+}
+
+export function missingForeignKey(table: string, key: ForeignKeyDescription): DriftDifference {
+  return {
+    kind: 'missing-foreign-key',
+    table,
+    column: null,
+    cause:
+      `table "${table}" has no foreign key on (${key.columns.join(', ')}) to ` +
+      `"${key.referencedTable}" (${key.referencedColumns.join(', ')}) that migrations declare`,
+    fix: 'x db migrate',
+  };
+}
+
+/**
+ * The key points where it was declared to point and one side's `on delete` rule is not the other's
+ * — reported apart from `missing-foreign-key` because it is a different repair: the constraint is
+ * there, and what changed is what happens to the child rows.
+ *
+ * The `fix` is the pair, not `x db migrate`: a rule cannot be altered in place, `add constraint`
+ * alone is `42710` on a name already taken, and no `x db gen` diff emits either statement, so
+ * naming a command would send a reader to one that generates an empty migration. Same reasoning
+ * as `changedColumn`.
+ */
+export function changedForeignKey(
+  table: string,
+  declared: ForeignKeyDescription,
+  held: ForeignKeyDescription,
+): DriftDifference {
+  const rule = onDeleteRule(held.onDelete);
+  return {
+    kind: 'changed-foreign-key',
+    table,
+    column: null,
+    cause:
+      `foreign key on "${table}" (${declared.columns.join(', ')}) to ` +
+      `"${declared.referencedTable}" ` +
+      `${rule === null ? 'declares no on delete rule' : `is on delete ${rule}`}, not what ` +
+      'migrations declare',
+    fix: `${rebuildForeignKey(table, declared, held)}   # in a new migration`,
+  };
+}

src/index-ddl.ts

+// Single responsibility: the DDL an entity's INDEX declaration becomes — the `create index` a
+// declaration writes out, what makes two definitions the same index, and what a moved definition
+// rebuilds. Split out of `generate.ts` at the 500-line ceiling, along the seam `check-ddl.ts` and
+// `generated-column.ts` already drew: `generate.ts` assembles a plan, this file writes the index
+// statements it puts in it, and `invariant-ddl.ts` decides which indexes a table declares.
+
+import { assert } from '@ultimat3/core';
+import type { EntityDescriptionLike, IndexDescriptionLike } from './entity-shape';
+import type { Plan } from './foreign-key-plan';
+import { declaredMethod, indexMethodOf, indexMethodSql } from './index-method';
+import type { IndexDescription } from './introspect';
+import { identifier } from './sql';
+
+/**
+ * A `unique` column clause already creates an index, and Postgres names it exactly what the
+ * entity's own convention names it — `<table>_<column>_key`. Emitting `create unique index` for
+ * it too is the same index twice: `42P07`, and a migration that cannot be applied at all.
+ * Mirrors the rule `entity()` already applies to a foreign key indexing its own column.
+ *
+ * A **partial** unique index is not that index: the column clause constrains every row, so
+ * skipping the partial one would silently widen the constraint the entity declared.
+ */
+export function impliedByColumnClause(
+  entity: EntityDescriptionLike,
+  index: IndexDescriptionLike,
+  added: ReadonlySet<string>,
+): boolean {
+  const [only] = index.columns;
+  if (!index.unique || index.where !== null || index.columns.length !== 1 || only === undefined) {
+    return false;
+  }
+  const column = entity.columns.find((each) => each.column === only);
+  // `columnClause` writes `unique` under exactly this condition — keep the two in step.
+  //
+  // NOT an optional chain, despite what biome's useOptionalChain suggests: `column?.unique` is
+  // `boolean | undefined`, and this function returns `boolean`. The lint rule marks its own fix
+  // unsafe for exactly this reason — applying it turned a green typecheck red.
+  // biome-ignore lint/complexity/useOptionalChain: an optional chain widens the return to include undefined
+  return column !== undefined && column.unique && !column.primaryKey && added.has(only);
+}
+
+/**
+ * Every part of the declaration reaches the statement: the whole column list in its declared
+ * order, the direction when one was asked for, and the predicate that makes it partial. A part
+ * dropped here is a constraint the database does not hold or an index the planner cannot use.
+ */
+export function createIndex(table: string, index: IndexDescriptionLike): string {
+  assert(
+    index.columns.length > 0,
+    `index "${index.name}" on "${table}" names no columns`,
+    `indexes: [{ on: ['<column>'] }]   # name the columns in the entity(), then x db gen`,
+  );
+  const method = index.using ?? 'btree';
+  // Two rules Postgres has and a declaration can break, refused here rather than at migrate time:
+  // GIN supports neither a unique index nor an ASC/DESC option, and either one reaches the server
+  // as a syntax error inside `ROLE=migrate` — a release phase that fails with the server's words
+  // and none of the entity's. `X_INVARIANT` for the reason `createIndex` already uses it on an
+  // index naming no columns: a declaration this build cannot honour is refused, never reinterpreted.
+  assert(
+    method === 'btree' || !index.unique,
+    `index "${index.name}" on "${table}" is unique and ${method}; Postgres has no unique ${method} index`,
+    `indexes: [{ on: ['<column>'], using: '${method}' }]   # drop unique, or drop using`,
+  );
+  assert(
+    method === 'btree' || index.order === null,
+    `index "${index.name}" on "${table}" is ${method} and ${index.order}; only a btree orders its keys`,
+    `indexes: [{ on: ['<column>'], using: '${method}' }]   # drop order, or drop using`,
+  );
+  const kind = index.unique ? 'create unique index' : 'create index';
+  const direction = index.order === null ? '' : ` ${index.order}`;
+  const columns = index.columns
+    .map((column) => `${identifier(column).text}${direction}`)
+    .join(', ');
+  const predicate = index.where === null ? '' : ` where (${index.where})`;
+  // Re-derived from the closed set, never spliced: `indexMethodSql` answers `''` for a btree, so
+  // an index that declared no method emits the statement this generator always emitted, byte for
+  // byte, and one that declared a method Postgres does not have is refused instead of built.
+  return (
+    `${kind} ${identifier(index.name).text} on ${identifier(table).text}` +
+    `${indexMethodSql(method)} (${columns})${predicate};`
+  );
+}
+
+/** `drop index "n";` — the one spelling, so a drop and its recreate cannot name it differently. */
+export const dropIndex = (name: string): string => `drop index ${identifier(name).text};`;
+
+/**
+ * A RECORDED index as a declaration this generator can emit again — `declaredMethod`, never a
+ * cast: the recorded side is typed open because the catalog shares the shape, and a method this
+ * generator cannot write must refuse rather than be rebuilt as a btree. One copy, because
+ * `redefineIndex`'s `down` and `retype-dependents.ts`'s restore ask the same question.
+ */
+export function asDeclared(index: IndexDescription): IndexDescriptionLike {
+  return {
+    name: index.name,
+    columns: index.columns,
+    unique: index.unique,
+    where: index.where,
+    order: index.order,
+    ...(index.using === undefined ? {} : { using: declaredMethod(index.using) }),
+  };
+}
+
+/** The parts of an index Postgres cannot alter in place — every one of them is a rebuild. */
+export function indexShape(index: IndexDescriptionLike | IndexDescription): string {
+  return JSON.stringify([
+    [...index.columns],
+    index.unique,
+    index.where,
+    index.order ?? null,
+    indexMethodOf(index),
+  ]);
+}
+
+/**
+ * A same-named index whose definition moved is dropped and recreated, because Postgres has no
+ * `alter index` for any of it — the column list, the uniqueness, the predicate and the direction
+ * are all fixed at creation.
+ *
+ * Matching on the name alone was the gap: `where` and `order` were not even recorded, so an
+ * entity narrowing an index to a predicate, or reversing it to `desc`, generated an empty
+ * migration and the database kept serving the old one. Both sides here are *generated* spellings
+ * — `recorded` is a previous migration's own snapshot, never the catalog's rewriting of it — so a
+ * text difference in `where` is a real change and not a formatting one.
+ */
+export function redefineIndex(
+  table: string,
+  index: IndexDescriptionLike,
+  recorded: IndexDescription,
+  plan: Plan,
+): void {
+  if (indexShape(index) === indexShape(recorded)) return;
+  plan.up.push(dropIndex(index.name), createIndex(table, index));
+  // `down` is reversed at assembly, so the pair is pushed forwards and read backwards: recreating
+  // the recorded definition is what must land last, after the new one is dropped.
+  plan.down.push(createIndex(table, asDeclared(recorded)), dropIndex(index.name));
+}

src/retype-dependents.ts

+// Single responsibility: which RECORDED objects a retype of one column breaks, and the statements
+// that take them out of the way before the ALTER and put them back in the `down`.
+//
+// Postgres compiles a partial index's predicate and a CHECK's expression against the column's type
+// at creation and cannot recompile either: `alter table "posts" alter column "status" type text
+// using "status"::text` answers `42883 operator does not exist: text = post_status` and the
+// migration aborts mid-run — inside `ROLE=migrate`, with the ledger recording nothing. Measured on
+// Postgres 18.4 (`generate-retype.live.test.ts`), one dependent shape at a time:
+//
+// | recorded object                          | survives the ALTER |
+// |------------------------------------------|--------------------|
+// | btree on the column, plain or unique      | yes — Postgres rebuilds it itself |
+// | composite btree including the column      | yes |
+// | partial index whose predicate names it    | **no — 42883** |
+// | partial index naming another column       | yes |
+// | CHECK whose expression names it           | **no — 42883** |
+//
+// So only an expression that MENTIONS the column is dependent, and dropping the rest would be a
+// table scan per index for nothing.
+
+import { addCheck, dropCheck } from './check-ddl';
+import type { Plan } from './foreign-key-plan';
+import { asDeclared, createIndex, dropIndex } from './index-ddl';
+import type { CheckDescription, IndexDescription, TableDescription } from './introspect';
+import { IDENTIFIER_PART, noiseAt } from './sql-scan';
+
+/**
+ * Whether `expression` reads `column`, over-approximating on purpose.
+ *
+ * The two errors are not symmetrical. A dependent object missed is `42883` in the release phase;
+ * one reported that was not is a rebuild nobody asked for — so every ambiguous case answers `true`,
+ * and the folding is case-insensitive because Postgres folds an unquoted identifier to lower case
+ * and `"Status"` naming a different column is a rarity beside a predicate this must not miss.
+ *
+ * What it does NOT count is noise, through this package's one lexer (`sql-scan.ts`): the `status`
+ * in `where kind = 'status'` is data, not a reference, and the one in `-- status` is prose. A
+ * QUOTED identifier is counted — `"status"` is the reference the catalog stores for an author who
+ * quoted it, and skipping it as noise is exactly the miss that ends in `42883`.
+ */
+export function referencesColumn(expression: string, column: string): boolean {
+  const wanted = column.toLowerCase();
+  let at = 0;
+  while (at < expression.length) {
+    const noise = noiseAt(expression, at);
+    if (noise !== null) {
+      if (
+        noise.kind === 'identifier' &&
+        expression.slice(at + 1, noise.end - 1).toLowerCase() === wanted
+      ) {
+        return true;
+      }
+      at = noise.end;
+      continue;
+    }
+    if (!IDENTIFIER_PART.test(expression[at] ?? '')) {
+      at += 1;
+      continue;
+    }
+    let end = at;
+    while (end < expression.length && IDENTIFIER_PART.test(expression[end] ?? '')) end += 1;
+    if (expression.slice(at, end).toLowerCase() === wanted) return true;
+    at = end;
+  }
+  return false;
+}
+
+/** The recorded objects a retype of `column` cannot leave in place. */
+export interface RetypeDependents {
+  /**
+   * Partial indexes whose predicate reads the column. A `primary` one is structurally impossible —
+   * a primary key index has no predicate — which is what keeps `drop index` off the two indexes
+   * Postgres refuses it on: a primary key's and a unique constraint's.
+   */
+  readonly indexes: readonly IndexDescription[];
+  /** CHECK constraints whose expression reads the column. */
+  readonly checks: readonly CheckDescription[];
+}
+
+/**
+ * What a retype of `table`.`column` breaks, read off the RECORDED schema — never the catalog.
+ * `x db gen` runs with no database open, so a hand-added expression index over the same column is
+ * invisible here and still `42883`; what this can see is every object a migration wrote down.
+ */
+export function retypeDependents(column: string, live: TableDescription): RetypeDependents {
+  return {
+    indexes: live.indexes.filter(
+      (index) => !index.primary && index.where !== null && referencesColumn(index.where, column),
+    ),
+    checks: (live.checks ?? []).filter((check) => referencesColumn(check.expression, column)),
+  };
+}
+
+/**
+ * What this plan has already dropped ahead of a retype — names only, because that is all the two
+ * readers need. The ordinary diff runs AFTER the ALTER and must not act on an object that is no
+ * longer there: the index loop CREATES a name in `indexes` instead of comparing it (a `drop index`
+ * on a name already dropped is `42704`, and a definition that never moved would emit nothing at
+ * all, leaving the table with no index), and `checkPlan` neither drops nor re-adds a name in
+ * `checks` — the declared side is added back by its own arm, and a recorded constraint the entity
+ * no longer declares is simply gone, which is what `checkPlan` would have done to it anyway.
+ */
+export interface MovedAside {
+  readonly indexes: Set<string>;
+  readonly checks: Set<string>;
+}
+
+/**
+ * Drop every dependent in `up`, restore it in `down`, and record what was moved.
+ *
+ * `down` is reversed at assembly, so the restores are pushed FORWARDS here and the retype's own
+ * reversal is pushed after them — the reversed script therefore reads: retype back to the old
+ * type, then recreate the objects that were compiled against it. Restoring first would recreate a
+ * predicate against a type the column no longer has, which is `42883` in the other direction.
+ *
+ * What is restored is what the snapshot RECORDED, never what the entity declares: an object still
+ * declared is re-created by the ordinary diff, one statement later, in its current shape.
+ */
+export function moveDependentsAside(
+  live: TableDescription,
+  column: string,
+  plan: Plan,
+  moved: MovedAside,
+): void {
+  const dependents = retypeDependents(column, live);
+  for (const index of dependents.indexes) {
+    plan.up.push(dropIndex(index.name));
+    plan.down.push(createIndex(live.name, asDeclared(index)));
+    moved.indexes.add(index.name);
+  }
+  for (const check of dependents.checks) {
+    plan.up.push(dropCheck(live.name, check.name));
+    plan.down.push(addCheck(live.name, check));
+    moved.checks.add(check.name);
+  }
+}

package.json

 {
   "name": "@ultimat3/db",
-  "version": "14.0.0",
+  "version": "15.0.0",
   "description": "Postgres access, transactions, migrations and drift detection",
@@ -34,3 +34,3 @@ "license": "MIT",
   "dependencies": {
-    "@ultimat3/core": "14.0.0"
+    "@ultimat3/core": "15.0.0"
   },
@@ -37,0 +37,0 @@ "peerDependencies": {

README.md

@@ -39,3 +39,3 @@ # @ultimat3/db 🐘
 | `isPlainRead()` | `As of 2026-08-24`: whether a statement may leave the primary. An allow-list — everything it cannot vouch for is the primary's |
-| `checkDrift()` / `diffSchema()` / `assertNoDrift()` | drift, with a `--json` report. `checkDrift()` is the **post-migrate verification** — the live database against the ledger: columns, declared indexes (access method `As of 2026-08-24`, columns, uniqueness, direction, and whether a predicate is there at all — never its text) and declared foreign keys, matched on where the key points and not on its constraint name, with the `on delete` rule compared through one normalisation `As of 2026-08-19` |
+| `checkDrift()` / `diffSchema()` / `assertNoDrift()` | drift, with a `--json` report. `checkDrift()` is the **post-migrate verification** — the live database against the ledger: columns, declared indexes (access method `As of 2026-08-24`, columns, uniqueness, direction, and whether a predicate is there at all — never its text), declared CHECK constraints by NAME (`missing-check`, `As of 2026-08-25` — never a predicate, which the catalog answers rewritten) and declared foreign keys, matched on where the key points and not on its constraint name, with the `on delete` rule compared through one normalisation `As of 2026-08-19` |
 | `declaredSchema()` / `expectedSchema()` | `As of 2026-08`: the schema the migrations write down, or `undefined` when the newest one carries no snapshot — never an older snapshot standing in for it |
@@ -46,3 +46,3 @@ | `parseSnapshot()` | `As of 2026-08`: a `<id>.snapshot.json` sidecar validated to the last nested field, or `undefined`. `{"tables":[null]}` is valid JSON and is not a schema |
 | `appTables()` / `FRAMEWORK_TABLE_PREFIX` | `As of 2026-08`: the live schema minus the `x_` namespace — no migration declares the ledger, the queue, the outbox or an auth table, so none of them is drift |
-| `generateMigration()` | `x db gen "<name>"` — reversible up/down SQL, and `destructive` for the marker the file must carry. `As of 2026-08` a foreign key is its own `alter table … add constraint`, emitted after every table statement: inline, a `references()` had to point at a table entity registration order happened to create first, and `down` had to drop them in an order it did not control. `As of 2026-08-19` a **removed** `references()` emits its `drop constraint` (it emitted nothing, and the snapshot then denied a constraint the database still held), a changed `onDelete` is a drop-and-add rebuild, and a declared `on delete` rule reaches the clause at all |
+| `generateMigration()` | `x db gen "<name>"` — reversible up/down SQL, and `destructive` for the marker the file must carry. `As of 2026-08` a foreign key is its own `alter table … add constraint`, emitted after every table statement: inline, a `references()` had to point at a table entity registration order happened to create first, and `down` had to drop them in an order it did not control. `As of 2026-08-19` a **removed** `references()` emits its `drop constraint` (it emitted nothing, and the snapshot then denied a constraint the database still held), a changed `onDelete` is a drop-and-add rebuild, and a declared `on delete` rule reaches the clause at all. `As of 2026-08-25` a **retype** drops the partial indexes and CHECK constraints written against that column first and restores them in `down`: Postgres compiles both predicates against the old type and cannot recompile either, so `alter column … type text using …::text` was `42883 operator does not exist: text = post_status` and the migration aborted mid-run. A plain btree over the column is left alone — measured, Postgres rebuilds that one itself |
 | `declaredIndexes()` / `invariantChecks()` / `constraintNameFor()` | `As of 2026-08-25`: the DDL an entity **invariant** becomes — a `check` as a named `CONSTRAINT`, a `unique` as a partial-capable unique INDEX, an `assert` as nothing. `EntityDescriptionLike` had no `invariants` field for three majors, so a regenerated migration silently held **none** of them, including the composite UNIQUE `upsertAll`'s `on conflict` is inferred against |
@@ -190,2 +190,13 @@ | `declaredChecks()` / `checkClauses()` / `checkPlan()` / `columnChecks()` / `columnCheckName()` / `columnNamesConstraint()` | `As of 2026-08-25`: **every** CHECK a table declares — a column's own (`enumerated()`'s value set, `tz()`'s IANA whitelist, `locale()`'s tags, money's currency pattern and scale bound) and an invariant's — on ONE list, so `createTable`, `diffTable` and `snapshotOf` agree about what exists. A column's check reached `create table` **inline and anonymous** and nothing else: the snapshot recorded none and the diff had no arm, so a value added to `enumerated()` generated no migration and a regenerated ENUM column came back as bare `text`. The name is `<table>_<column>_check` because that is the name **Postgres itself mints** for the old anonymous form — measured — so the repair lands on the constraint an already-generated database is holding; `checkPlan` emits `drop constraint if exists` before the `add` for exactly that column, because a bare add is `42710` there and a no-op everywhere else |
 
+**A CHECK the catalog no longer holds is drift, `As of 2026-08-25` — by NAME.**
+`pg_get_constraintdef` answers Postgres' own rewriting (`status in ('draft', 'published')` reads
+back as `CHECK ((status = ANY (ARRAY['draft'::text, 'published'::text])))`), so the catalog side is
+read as `conname` alone and lands on `TableDescription.checkNames`, a **separate field** from the
+declaration's `checks`. Only the declared side is judged, so a NOT NULL, an `enumerated()` column's
+old anonymous form and an extension's own constraint are all silent; a declared one the catalog
+does not hold is `missing-check`, whose `fix:` is the `add constraint` statement itself, because the
+migration that declares it is already in the ledger and `x db migrate` would apply nothing. There is
+no `changed-check`: presence is a boolean, a predicate is text, and normalising the text is an
+expression parser competing with the server's.
+
 **Nor is a relation an extension owns, `As of 2026-08-24`.** `create extension pg_stat_statements`
@@ -192,0 +203,0 @@ in `public` is the CNPG, RDS, Supabase and Neon default, and its view read as `unexpected-table`

src/check-ddl.ts

@@ -128,7 +128,9 @@ // Single responsibility: every CHECK constraint a table declares — a COLUMN's own and an
 
-const addCheck = (table: string, check: CheckDescription): string =>
+/** Exported for `retype-dependents.ts`: a constraint moved out of a retype's way is put back by
+ * the same statement that would have added it, never by a second spelling of `add constraint`. */
+export const addCheck = (table: string, check: CheckDescription): string =>
   `alter table ${identifier(table).text} add constraint ${identifier(check.name).text} ` +
   `check (${check.expression});`;
 
-const dropCheck = (table: string, name: string): string =>
+export const dropCheck = (table: string, name: string): string =>
   `alter table ${identifier(table).text} drop constraint ${identifier(name).text};`;
@@ -165,2 +167,10 @@
  * one level in.
+ *
+ * `predropped` names the CONSTRAINTS this plan already dropped, ahead of a retype whose predicate
+ * they were compiled against (`retype-dependents.ts`). Two arms read it and both are about a name
+ * that is provably free: a declared one takes the bare `add constraint` rather than the
+ * drop-if-exists pair, and a recorded one the entity no longer declares is left alone entirely —
+ * `drop constraint` on it a second time is `42704`, and its `down` belongs to the retype that
+ * moved it. Keyed by name and not by column because an INVARIANT's check reads a column without
+ * being derived from one, which is exactly the constraint `examples/dummy` retypes under.
  */
@@ -172,2 +182,3 @@ export function checkPlan(
   rebuilt: ReadonlySet<string> = new Set(),
+  predropped: ReadonlySet<string> = new Set(),
 ): void {
@@ -195,6 +206,7 @@ const recorded = new Map((live.checks ?? []).map((check) => [check.name, check]));
   for (const check of wanted) {
-    const held = dropped.has(check.name) ? undefined : recorded.get(check.name);
+    const gone = dropped.has(check.name) || predropped.has(check.name);
+    const held = gone ? undefined : recorded.get(check.name);
     if (held === undefined) {
       plan.up.push(
-        ...(exposed.has(check.name)
+        ...(exposed.has(check.name) && !predropped.has(check.name)
           ? rebuildCheck(entity.table, check)
@@ -212,3 +224,3 @@ : [addCheck(entity.table, check)]),
   for (const check of live.checks ?? []) {
-    if (declared.has(check.name)) continue;
+    if (declared.has(check.name) || predropped.has(check.name)) continue;
     plan.up.push(dropCheck(entity.table, check.name));
@@ -215,0 +227,0 @@ plan.down.push(addCheck(entity.table, check));

src/drift.ts

@@ -7,34 +7,26 @@ // Single responsibility: prove the live schema and the migration ledger agree. Drift is the
 import { baseClient, type DbClient } from './client';
+import type { DriftDifference } from './drift-findings';
+import {
+  changedColumn,
+  changedForeignKey,
+  changedIndex,
+  missingCheck,
+  missingColumn,
+  missingForeignKey,
+  missingIndex,
+  missingTable,
+  unexpectedColumn,
+  unexpectedTable,
+  unknownSchema,
+} from './drift-findings';
 import { DbError } from './errors';
-import { foreignKeyTarget, onDeleteRule, rebuildForeignKey } from './foreign-key';
+import { foreignKeyTarget, onDeleteRule } from './foreign-key';
 import { indexMethodOf } from './index-method';
-import {
-  type ForeignKeyDescription,
-  findTable,
-  introspect,
-  type SchemaDescription,
-  type TableDescription,
-} from './introspect';
+import { findTable, introspect, type SchemaDescription, type TableDescription } from './introspect';
 import { type LedgerRow, type Migration, readLedger } from './migrate';
 
-export type DriftKind =
-  | 'unexpected-column'
-  | 'missing-column'
-  | 'changed-column'
-  | 'unexpected-table'
-  | 'missing-table'
-  | 'unknown-schema'
-  | 'missing-index'
-  | 'changed-index'
-  | 'missing-foreign-key'
-  | 'changed-foreign-key';
+// Re-exported explicitly, never `export *`: `src/index.ts` publishes both from `'./drift'`, so the
+// split is invisible to `@ultimat3/db`'s public surface and no consumer moves with it.
+export type { DriftDifference, DriftKind } from './drift-findings';
 
-export interface DriftDifference {
-  readonly kind: DriftKind;
-  readonly table: string;
-  readonly column: string | null;
-  readonly cause: string;
-  readonly fix: string;
-}
-
 export interface DriftReport {
@@ -45,158 +37,3 @@ readonly ok: boolean;
 
-function unexpectedColumn(table: string, column: string): DriftDifference {
-  return {
-    kind: 'unexpected-column',
-    table,
-    column,
-    // Pinned by the contract. Do not reword without changing docs/errors/X_DB_DRIFT.
-    cause: `table "${table}" has column "${column}" not present in any migration`,
-    fix: `x db gen "add ${column}"`,
-  };
-}
-
-function missingColumn(table: string, column: string): DriftDifference {
-  return {
-    kind: 'missing-column',
-    table,
-    column,
-    cause: `table "${table}" is missing column "${column}" that migrations declare`,
-    fix: 'x db migrate',
-  };
-}
-
 /**
- * The column exists on both sides and one of them lets it be `NULL`.
- *
- * This is the finding the expand/contract flow needs and never had. `generate.ts` emits a `NOT
- * NULL` add as nullable plus a `-- backfill "c", then: … set not null;` comment, because the
- * strict version cannot succeed on a populated table — and phase 2 is a comment, so it is a thing
- * a human has to remember. Nobody did, and `compareTable` compared columns by name and by type
- * while `snapshotOf` had recorded `nullable` all along, so the column stayed nullable forever
- * against an entity schema that said otherwise, with `ok: true` on every check. The first
- * `undefined` write then lands as `NULL` and crashes three services away from the migration.
- *
- * `x db gen` is deliberately not the fix: it diffs types and indexes and has never emitted a
- * `set not null`, so naming it would send a reader to a command that generates an empty migration.
- */
-function changedColumn(table: string, column: string, liveNullable: boolean): DriftDifference {
-  const clause = liveNullable ? 'set not null' : 'drop not null';
-  return {
-    kind: 'changed-column',
-    table,
-    column,
-    cause: liveNullable
-      ? `table "${table}" allows NULL in column "${column}" that migrations declare not null`
-      : `table "${table}" forbids NULL in column "${column}" that migrations declare nullable`,
-    fix:
-      `alter table "${table}" alter column "${column}" ${clause};   # in a new migration` +
-      (liveNullable ? ' — backfill the existing NULLs first' : ''),
-  };
-}
-
-function unexpectedTable(table: string): DriftDifference {
-  return {
-    kind: 'unexpected-table',
-    table,
-    column: null,
-    cause: `table "${table}" is not present in any migration`,
-    fix: `x db gen "add ${table}"`,
-  };
-}
-
-function missingTable(table: string): DriftDifference {
-  return {
-    kind: 'missing-table',
-    table,
-    column: null,
-    cause: `table "${table}" is declared by migrations but does not exist`,
-    fix: 'x db migrate',
-  };
-}
-
-/**
- * Not a difference between two schemas but the absence of one to compare against — reported
- * through the same channel so it reaches an operator, since a check that quietly answered "clean"
- * because it had nothing to check is the one failure mode drift detection cannot have.
- */
-function unknownSchema(migrations: readonly Migration[]): DriftDifference {
-  const newest = [...migrations].sort((a, b) => (a.id < b.id ? -1 : 1)).at(-1);
-  return {
-    kind: 'unknown-schema',
-    table: '',
-    column: null,
-    cause:
-      `migration "${newest?.id ?? ''}" records no schema snapshot, so what this database owes ` +
-      'cannot be established',
-    // The same two remedies `X_MIGRATION_SNAPSHOT_MISSING` names, in the same order, because it is
-    // the same condition. It used to lead with `x db gen`, which raises that error and whose own
-    // fix pointed back here — a cycle a scaffolded app hit on its first `x db migrate`. The
-    // pathspec is a glob because this package is tier 1: only `@ultimat3/cli` knows the directory.
-    fix:
-      `git checkout -- "*${newest?.id ?? ''}.snapshot.json"   # or, if it was never written: ` +
-      `delete migration "${newest?.id ?? ''}" and rerun x db gen "${newest?.name ?? 'initial'}"`,
-  };
-}
-
-function missingIndex(table: string, index: string): DriftDifference {
-  return {
-    kind: 'missing-index',
-    table,
-    column: null,
-    cause: `table "${table}" is missing index "${index}" that migrations declare`,
-    fix: 'x db migrate',
-  };
-}
-
-function changedIndex(table: string, index: string, detail: string): DriftDifference {
-  return {
-    kind: 'changed-index',
-    table,
-    column: null,
-    cause: `index "${index}" on "${table}" ${detail}, not what migrations declare`,
-    fix: 'x db migrate',
-  };
-}
-
-function missingForeignKey(table: string, key: ForeignKeyDescription): DriftDifference {
-  return {
-    kind: 'missing-foreign-key',
-    table,
-    column: null,
-    cause:
-      `table "${table}" has no foreign key on (${key.columns.join(', ')}) to ` +
-      `"${key.referencedTable}" (${key.referencedColumns.join(', ')}) that migrations declare`,
-    fix: 'x db migrate',
-  };
-}
-
-/**
- * The key points where it was declared to point and one side's `on delete` rule is not the other's
- * — reported apart from `missing-foreign-key` because it is a different repair: the constraint is
- * there, and what changed is what happens to the child rows.
- *
- * The `fix` is the pair, not `x db migrate`: a rule cannot be altered in place, `add constraint`
- * alone is `42710` on a name already taken, and no `x db gen` diff emits either statement, so
- * naming a command would send a reader to one that generates an empty migration. Same reasoning
- * as `changedColumn`.
- */
-function changedForeignKey(
-  table: string,
-  declared: ForeignKeyDescription,
-  held: ForeignKeyDescription,
-): DriftDifference {
-  const rule = onDeleteRule(held.onDelete);
-  return {
-    kind: 'changed-foreign-key',
-    table,
-    column: null,
-    cause:
-      `foreign key on "${table}" (${declared.columns.join(', ')}) to ` +
-      `"${declared.referencedTable}" ` +
-      `${rule === null ? 'declares no on delete rule' : `is on delete ${rule}`}, not what ` +
-      'migrations declare',
-    fix: `${rebuildForeignKey(table, declared, held)}   # in a new migration`,
-  };
-}
-
-/**
  * Indexes migrations declare, against the ones the catalog holds — by column list and by
@@ -320,2 +157,29 @@ * uniqueness, which is what caught a composite index rebuilt with its columns the other way round
 /**
+ * CHECK constraints migrations declare, against the NAMES the catalog holds — `checkNames`, which
+ * is a separate field from `checks` precisely so this comparison cannot reach a definition it must
+ * not read (`introspect.ts`).
+ *
+ * Two absences, and they mean opposite things. `expected.checks` absent is a sidecar written
+ * before constraints were recorded: it declares nothing, so nothing can be missing. `live.checkNames`
+ * absent is a description that never asked the catalog — a stub, a fake client's rows, a
+ * `TableDescription` built by hand — and reading that as "the database holds none" is one finding
+ * per declared constraint against a database nobody looked at. `introspect()` always answers with
+ * the field, `[]` included, so a real read is never mistaken for an unread one.
+ *
+ * Only the declared side is judged, the rule `compareIndexes` and `compareForeignKeys` both state:
+ * a NOT NULL, an `enumerated()` column's old anonymous form, a constraint an extension brought and
+ * every hand-written CHECK an app has ever added would each be a finding against a database that
+ * is exactly right.
+ */
+function compareChecks(live: TableDescription, expected: TableDescription): DriftDifference[] {
+  const declared = expected.checks;
+  const held = live.checkNames;
+  if (declared === undefined || held === undefined) return [];
+  const present = new Set(held);
+  return declared
+    .filter((check) => !present.has(check.name))
+    .map((check) => missingCheck(live.name, check));
+}
+
+/**
  * A primary key column is `NOT NULL` in the catalog whether or not anything declared it — Postgres
@@ -356,2 +220,3 @@ * adds the constraint with the key. Both sides are therefore read through the union of the two
   differences.push(...compareIndexes(live, expected));
+  differences.push(...compareChecks(live, expected));
   differences.push(...compareForeignKeys(live, expected));
@@ -358,0 +223,0 @@ return differences;

src/generate.ts

@@ -6,3 +6,3 @@ // Single responsibility: turn an entity snapshot into a timestamped, reversible migration.
 
-import { assert, systemClock } from '@ultimat3/core';
+import { systemClock } from '@ultimat3/core';
 import { checkClauses, checkPlan, declaredChecks } from './check-ddl';
@@ -12,7 +12,3 @@ import { defaultExpression } from './column-default';
 import { dropOrder } from './drop-order';
-import type {
-  ColumnDescriptionLike,
-  EntityDescriptionLike,
-  IndexDescriptionLike,
-} from './entity-shape';
+import type { ColumnDescriptionLike, EntityDescriptionLike } from './entity-shape';
 import { migrationIrreversible } from './errors';
@@ -22,7 +18,6 @@ import { type ConstraintPlans, foreignKeyPlan, foreignKeysOf, type Plan } from './foreign-key-plan';
 import { generatedClause, isGenerated, regenerate } from './generated-column';
-import { declaredMethod, indexMethodOf, indexMethodSql } from './index-method';
+import { createIndex, dropIndex, impliedByColumnClause, redefineIndex } from './index-ddl';
 import {
   type ColumnDescription,
   findTable,
-  type IndexDescription,
   type SchemaDescription,
@@ -32,2 +27,4 @@ type TableDescription,
 import { declaredIndexes } from './invariant-ddl';
+import type { MovedAside } from './retype-dependents';
+import { moveDependentsAside } from './retype-dependents';
 import { identifier } from './sql';
@@ -81,30 +78,2 @@ import { type UnrenderedDeclaration, unrenderedComment, unrenderedOf } from './unrendered';
 
-/**
- * A `unique` column clause already creates an index, and Postgres names it exactly what the
- * entity's own convention names it — `<table>_<column>_key`. Emitting `create unique index` for
- * it too is the same index twice: `42P07`, and a migration that cannot be applied at all.
- * Mirrors the rule `entity()` already applies to a foreign key indexing its own column.
- *
- * A **partial** unique index is not that index: the column clause constrains every row, so
- * skipping the partial one would silently widen the constraint the entity declared.
- */
-function impliedByColumnClause(
-  entity: EntityDescriptionLike,
-  index: IndexDescriptionLike,
-  added: ReadonlySet<string>,
-): boolean {
-  const [only] = index.columns;
-  if (!index.unique || index.where !== null || index.columns.length !== 1 || only === undefined) {
-    return false;
-  }
-  const column = entity.columns.find((each) => each.column === only);
-  // `columnClause` writes `unique` under exactly this condition — keep the two in step.
-  //
-  // NOT an optional chain, despite what biome's useOptionalChain suggests: `column?.unique` is
-  // `boolean | undefined`, and this function returns `boolean`. The lint rule marks its own fix
-  // unsafe for exactly this reason — applying it turned a green typecheck red.
-  // biome-ignore lint/complexity/useOptionalChain: an optional chain widens the return to include undefined
-  return column !== undefined && column.unique && !column.primaryKey && added.has(only);
-}
-
 export function snapshotOf(entities: readonly EntityDescriptionLike[]): SchemaDescription {
@@ -181,44 +150,2 @@ const tables = [...entities]
 /**
- * Every part of the declaration reaches the statement: the whole column list in its declared
- * order, the direction when one was asked for, and the predicate that makes it partial. A part
- * dropped here is a constraint the database does not hold or an index the planner cannot use.
- */
-function createIndex(table: string, index: IndexDescriptionLike): string {
-  assert(
-    index.columns.length > 0,
-    `index "${index.name}" on "${table}" names no columns`,
-    `indexes: [{ on: ['<column>'] }]   # name the columns in the entity(), then x db gen`,
-  );
-  const method = index.using ?? 'btree';
-  // Two rules Postgres has and a declaration can break, refused here rather than at migrate time:
-  // GIN supports neither a unique index nor an ASC/DESC option, and either one reaches the server
-  // as a syntax error inside `ROLE=migrate` — a release phase that fails with the server's words
-  // and none of the entity's. `X_INVARIANT` for the reason `createIndex` already uses it on an
-  // index naming no columns: a declaration this build cannot honour is refused, never reinterpreted.
-  assert(
-    method === 'btree' || !index.unique,
-    `index "${index.name}" on "${table}" is unique and ${method}; Postgres has no unique ${method} index`,
-    `indexes: [{ on: ['<column>'], using: '${method}' }]   # drop unique, or drop using`,
-  );
-  assert(
-    method === 'btree' || index.order === null,
-    `index "${index.name}" on "${table}" is ${method} and ${index.order}; only a btree orders its keys`,
-    `indexes: [{ on: ['<column>'], using: '${method}' }]   # drop order, or drop using`,
-  );
-  const kind = index.unique ? 'create unique index' : 'create index';
-  const direction = index.order === null ? '' : ` ${index.order}`;
-  const columns = index.columns
-    .map((column) => `${identifier(column).text}${direction}`)
-    .join(', ');
-  const predicate = index.where === null ? '' : ` where (${index.where})`;
-  // Re-derived from the closed set, never spliced: `indexMethodSql` answers `''` for a btree, so
-  // an index that declared no method emits the statement this generator always emitted, byte for
-  // byte, and one that declared a method Postgres does not have is refused instead of built.
-  return (
-    `${kind} ${identifier(index.name).text} on ${identifier(table).text}` +
-    `${indexMethodSql(method)} (${columns})${predicate};`
-  );
-}
-
-/**
  * Skipping an existing column by name alone missed the type moving under it: a table created
@@ -229,10 +156,18 @@ * while money's currency was bare `char` keeps `char(1)` and rejects every ISO 4217 code, yet the
  * difference is a real kind change, not a catalog alias.
+ *
+ * The ALTER is not the whole statement list: Postgres compiled every predicate written against
+ * this column with its OLD type and cannot recompile one, so a partial index or a CHECK that reads
+ * it is dropped FIRST and `moved` carries the names on to the arms that would otherwise act on
+ * them. Without that the retype is `42883` and the migration aborts mid-run
+ * (`retype-dependents.ts`).
  */
 function retypeColumn(
-  table: string,
+  live: TableDescription,
   column: ColumnDescriptionLike,
   recorded: ColumnDescription,
   plan: Plan,
+  moved: MovedAside,
 ): Regeneration {
   const wanted = sqlType(column.kind);
+  const table = live.name;
   // A generated column moves by its own rules — see `generated-column.ts`. Asked whenever EITHER
@@ -244,2 +179,3 @@ // side is one, because becoming generated and ceasing to be are both changes with a statement.
   if (recorded.dataType === wanted) return 'unchanged';
+  moveDependentsAside(live, column.column, plan, moved);
   const alter = (type: string): string =>
@@ -253,50 +189,2 @@ `alter table ${identifier(table).text} alter column ${identifier(column.column).text} ` +
 
-/** The parts of an index Postgres cannot alter in place — every one of them is a rebuild. */
-function indexShape(index: IndexDescriptionLike | IndexDescription): string {
-  return JSON.stringify([
-    [...index.columns],
-    index.unique,
-    index.where,
-    index.order ?? null,
-    indexMethodOf(index),
-  ]);
-}
-
-/**
- * A same-named index whose definition moved is dropped and recreated, because Postgres has no
- * `alter index` for any of it — the column list, the uniqueness, the predicate and the direction
- * are all fixed at creation.
- *
- * Matching on the name alone was the gap: `where` and `order` were not even recorded, so an
- * entity narrowing an index to a predicate, or reversing it to `desc`, generated an empty
- * migration and the database kept serving the old one. Both sides here are *generated* spellings
- * — `recorded` is a previous migration's own snapshot, never the catalog's rewriting of it — so a
- * text difference in `where` is a real change and not a formatting one.
- */
-function redefineIndex(
-  table: string,
-  index: IndexDescriptionLike,
-  recorded: IndexDescription,
-  plan: Plan,
-): void {
-  if (indexShape(index) === indexShape(recorded)) return;
-  plan.up.push(`drop index ${identifier(index.name).text};`, createIndex(table, index));
-  // `down` is reversed at assembly, so the pair is pushed forwards and read backwards: recreating
-  // the recorded definition is what must land last, after the new one is dropped.
-  plan.down.push(
-    createIndex(table, {
-      name: recorded.name,
-      columns: recorded.columns,
-      unique: recorded.unique,
-      where: recorded.where,
-      order: recorded.order,
-      // `declaredMethod`, never a cast: `recorded` is a snapshot's, typed open because the catalog
-      // shares the shape, and a method this generator cannot emit must refuse rather than be
-      // rebuilt as a btree — a `down` that recreates the wrong structure is worse than none.
-      ...(recorded.using === undefined ? {} : { using: declaredMethod(recorded.using) }),
-    }),
-    `drop index ${identifier(index.name).text};`,
-  );
-}
-
 function diffTable(entity: EntityDescriptionLike, live: TableDescription, plan: Plan): void {
@@ -308,6 +196,8 @@ const existing = new Map(live.columns.map((column) => [column.name, column]));
   const rebuilt = new Set<string>();
+  // What a retype dropped ahead of itself, read by the two arms below.
+  const moved: MovedAside = { indexes: new Set(), checks: new Set() };
   for (const column of entity.columns) {
     const recorded = existing.get(column.column);
     if (recorded !== undefined) {
-      if (retypeColumn(entity.table, column, recorded, plan) === 'rebuilt') {
+      if (retypeColumn(live, column, recorded, plan, moved) === 'rebuilt') {
         rebuilt.add(column.column);
@@ -342,5 +232,7 @@ }
     const recorded = indexed.get(index.name);
-    // A rebuilt column took its indexes down with it, so this one is CREATED rather than compared:
+    // A rebuilt column took its indexes down with it, and a retype dropped the ones whose
+    // predicate it could not survive — either way this one is CREATED rather than compared:
     // `redefineIndex` sees a definition that never moved and would emit nothing at all.
-    if (recorded !== undefined && !index.columns.some((column) => rebuilt.has(column))) {
+    const gone = moved.indexes.has(index.name) || index.columns.some((each) => rebuilt.has(each));
+    if (recorded !== undefined && !gone) {
       redefineIndex(entity.table, index, recorded, plan);
@@ -353,3 +245,3 @@ continue;
     plan.up.push(createIndex(entity.table, index));
-    plan.down.push(`drop index ${identifier(index.name).text};`);
+    plan.down.push(dropIndex(index.name));
   }
@@ -359,4 +251,5 @@
   // that does not exist yet is `42703`. `check-ddl.ts` owns which of them move; `rebuilt` because a
-  // column dropped and re-added lost its constraint while the snapshot still records it.
-  checkPlan(entity, live, plan, rebuilt);
+  // column dropped and re-added lost its constraint while the snapshot still records it, and
+  // `moved.checks` because a retype already dropped the ones written against the old type.
+  checkPlan(entity, live, plan, rebuilt, moved.checks);
 }
@@ -363,0 +256,0 @@

src/introspect.ts

@@ -90,2 +90,20 @@ // Single responsibility: read the live schema out of `information_schema` / `pg_catalog` into a
   readonly checks?: readonly CheckDescription[] | undefined;
+  /**
+   * The catalog's half of `checks`, and a **separate field rather than the same one** — names
+   * only, `conname` for `contype = 'c'`, never a definition.
+   *
+   * The two readings cannot share `checks` because they are not the same value. A catalog read
+   * carries Postgres' own rewriting of the predicate and a declaration carries this generator's
+   * spelling, so a `checks` filled from `pg_constraint` would put a rewritten expression on the
+   * field `checkPlan` diffs against a generated one — every regenerated migration would then drop
+   * and re-add every constraint in the app, forever, because the two strings can never be equal.
+   * Splitting them means the type says which reading a value came from, and `checkPlan` cannot be
+   * handed a catalog value by accident.
+   *
+   * `snapshotOf` never writes it and `parseSnapshot` never reads it, so a sidecar carries `checks`
+   * alone. `introspect()` always answers with it, `[]` included: absent therefore means "nobody
+   * asked the catalog", which is what keeps `compareChecks` silent on a description that never
+   * read one instead of reporting every declared constraint as missing.
+   */
+  readonly checkNames?: readonly string[] | undefined;
 }
@@ -139,2 +157,8 @@
 
+/** A CHECK constraint's NAME. There is deliberately no column for its definition — see `checkNames`. */
+interface CheckRow {
+  readonly table_name: string;
+  readonly constraint_name: string;
+}
+
 const byName = (a: { name: string }, b: { name: string }): number => (a.name < b.name ? -1 : 1);
@@ -211,3 +235,17 @@
 
-  return buildSchema(schema, excluded, columns, indexes, foreignKeys);
+  // `conname` and nothing else. `pg_get_constraintdef(c.oid)` is one word further along this line
+  // and is the reason this query did not exist: it answers Postgres' rewriting of the predicate,
+  // which no generated spelling can ever equal, so reading it would make every drift check report
+  // a correct database as wrong. `contype = 'c'` is the CHECK constraints alone — Postgres 17
+  // onwards records a NOT NULL as `'n'`, and a domain's as `'c'` on the domain rather than here.
+  const checks = await client.query<CheckRow>(sql`
+    select src.relname as table_name, c.conname as constraint_name
+    from pg_constraint c
+    join pg_class src on src.oid = c.conrelid
+    join pg_namespace n on n.oid = src.relnamespace
+    where c.contype = 'c' and n.nspname = ${schema} and src.relkind = 'r'
+    order by src.relname, c.conname
+  `);
+
+  return buildSchema(schema, excluded, columns, indexes, foreignKeys, checks);
 }
@@ -222,2 +260,3 @@
   foreignKeys: readonly ForeignKeyRow[],
+  checks: readonly CheckRow[] = [],
 ): SchemaDescription {
@@ -268,2 +307,8 @@ const names = [...new Set(columns.map((row) => row.table_name))]
         .sort(byName),
+      // Always written, `[]` included: this reading of a table HAS asked the catalog, and absence
+      // is reserved for a description that has not (`compareChecks` is silent on that one).
+      checkNames: checks
+        .filter((row) => row.table_name === name)
+        .map((row) => row.constraint_name)
+        .sort(),
     };
@@ -270,0 +315,0 @@ });

No alert changes

Improved metrics

Total package byte prevSize

499231

5.5%

Number of package files

58

5.45%

Lines of code

7136

4.42%

Number of lines in readme file

442

2.55%

Dependency changes

• + Added

  @ultimat3/core@15.0.0
  (transitive)

• - Removed

  @ultimat3/core@14.0.0
  (transitive)

• Updated

  @ultimat3/core@15.0.0