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+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * [#25521 cut 6] The two in-place drift reconcilers of `SqlDriver`'s schema
+ * sync — `applyDriftOpInPlace`, which applies one column drift op as a dialect
+ * `ALTER` on Postgres and MySQL, and `rebuildSqliteTablePatched`, the SQLite
+ * table rebuild that applies a set of them — moved out of `sql-driver.ts`
+ * whole. `applyMigrationEntries`, which calls both, stays in the class, as do
+ * the members the two bodies call (`applyIndexDriftOp`, `buildRebuiltColumn`,
+ * `syncTableIndexes` and the rest).
+ *
+ * A MOVE, not a redesign. Each function below is the body of the `SqlDriver`
+ * method of the same name as it stood, re-indented one level and otherwise
+ * unedited: the same dialect statements, the same rebuild procedure, the same
+ * honoured-entries contract.
+ *
+ * ## How the moved bodies reach the class
+ *
+ * The shape `sql-driver-introspection.ts` (cut 1) applies, after #23050. The
+ * class keeps both methods, because the published `dist/*.d.ts` lists each
+ * one's name, docblock and position, and tests call both on the driver. Each
+ * body is now one literal of exactly the {@link SchemaSyncHost} members that
+ * method reads, plus a `.call`. The methods are no longer `async`: each
+ * returns the moved function's own promise, so a caller awaits the same
+ * promise the body settles, with no extra wrapper.
+ *
+ * The methods the bodies call go as closures that call them on the driver at
+ * call time, so a subclass override or a test spy on the instance is still the
+ * one the body reaches. The fields `knex`, `logger`, `managedObjectFields` and
+ * `managedObjectIndexes`, the getter `dialectName` and the two dialect getters
+ * go as GETTERS, so each read happens when the body makes it, as it did on the
+ * class; `this.logger.warn(...)` still calls `warn` on the logger itself.
+ *
+ * The module-level declarations the bodies read, `isIndexDriftOp` and the
+ * types `DriftOp` and `ManagedDriftEntry`, live in `schema-drift.ts`, which
+ * exports them, and are imported from there; `sql-driver.ts` still reads all
+ * three. `index.ts` re-exports nothing from this module, so the published
+ * surface does not move.
+ */
+
+import { isIndexDriftOp, type DriftOp, type ManagedDriftEntry } from './schema-drift.js';
+import type { SqlDriver } from './sql-driver.js';
+
+/**
+ * The `SqlDriver` members the functions below read — every one of them, and
+ * no other; each function's `this` is the `Pick` of the members IT reads. Each
+ * is typed AS the class member (an indexed access on the class), so a change
+ * to a member's signature on the class is a change here too, and naming a
+ * member the class does not have is a compile error. See the module header
+ * for which members are getters.
+ */
+export interface SchemaSyncHost {
+  applyDeclaredColumnDefault: SqlDriver['applyDeclaredColumnDefault'];
+  applyIndexDriftOp: SqlDriver['applyIndexDriftOp'];
+  buildRebuiltColumn: SqlDriver['buildRebuiltColumn'];
+  readonly dialectName: SqlDriver['dialectName'];
+  introspectColumns: SqlDriver['introspectColumns'];
+  readonly isMysql: SqlDriver['isMysql'];
+  readonly isPostgres: SqlDriver['isPostgres'];
+  readonly knex: SqlDriver['knex'];
+  readonly logger: SqlDriver['logger'];
+  readonly managedObjectFields: SqlDriver['managedObjectFields'];
+  readonly managedObjectIndexes: SqlDriver['managedObjectIndexes'];
+  nowColumnDefault: SqlDriver['nowColumnDefault'];
+  resolveTenantField: SqlDriver['resolveTenantField'];
+  syncTableIndexes: SqlDriver['syncTableIndexes'];
+}
+
+/** The body of `SqlDriver#applyDriftOpInPlace`; the method's docblock there is its contract. */
+export async function applyDriftOpInPlace(this: Pick<SchemaSyncHost, 'applyIndexDriftOp' | 'dialectName' | 'isMysql' | 'isPostgres' | 'knex' | 'logger'>, op: DriftOp): Promise<boolean> {
+  // Index ops need no dialect-specific ALTER — route them to the portable path.
+  if (isIndexDriftOp(op)) return this.applyIndexDriftOp(op);
+  const { table, column } = op;
+  if (this.isPostgres) {
+    switch (op.type) {
+      case 'relax_not_null':
+        await this.knex.raw('ALTER TABLE ?? ALTER COLUMN ?? DROP NOT NULL', [table, column]);
+        return true;
+      case 'tighten_not_null':
+        await this.knex.raw('ALTER TABLE ?? ALTER COLUMN ?? SET NOT NULL', [table, column]);
+        return true;
+      case 'widen_varchar':
+      case 'narrow_varchar':
+        await this.knex.raw(`ALTER TABLE ?? ALTER COLUMN ?? TYPE varchar(${op.to})`, [table, column]);
+        return true;
+      case 'drop_column':
+        await this.knex.raw('ALTER TABLE ?? DROP COLUMN ??', [table, column]);
+        return true;
+      case 'drop_column_default':
+        await this.knex.raw('ALTER TABLE ?? ALTER COLUMN ?? DROP DEFAULT', [table, column]);
+        return true;
+    }
+  }
+  if (this.isMysql) {
+    // MySQL MODIFY restates the FULL column definition — reconstruct the
+    // type (with length for char types, so a nullability change never
+    // silently drops a varchar's declared length) from columnInfo.
+    const info: any = await this.knex(table).columnInfo();
+    const ci: any = info?.[column];
+    const colType: string | undefined = ci?.type
+      ? (/char/i.test(ci.type) && ci.maxLength ? `${ci.type}(${ci.maxLength})` : ci.type)
+      : undefined;
+    switch (op.type) {
+      case 'relax_not_null':
+        if (!colType) return false;
+        await this.knex.raw(`ALTER TABLE ?? MODIFY ?? ${colType} NULL`, [table, column]);
+        return true;
+      case 'tighten_not_null':
+        if (!colType) return false;
+        await this.knex.raw(`ALTER TABLE ?? MODIFY ?? ${colType} NOT NULL`, [table, column]);
+        return true;
+      case 'widen_varchar':
+      case 'narrow_varchar':
+        await this.knex.raw(`ALTER TABLE ?? MODIFY ?? varchar(${op.to})`, [table, column]);
+        return true;
+      case 'drop_column':
+        await this.knex.raw('ALTER TABLE ?? DROP COLUMN ??', [table, column]);
+        return true;
+      case 'drop_column_default':
+        // `ALTER … ALTER COLUMN … DROP DEFAULT` — the one ALTER COLUMN form
+        // MySQL accepts without restating the type, so it cannot lose a
+        // varchar length the way MODIFY can.
+        await this.knex.raw('ALTER TABLE ?? ALTER COLUMN ?? DROP DEFAULT', [table, column]);
+        return true;
+    }
+  }
+  this.logger.warn(`[schema-drift] ${op.type} on ${table}.${column} is unsupported on dialect '${this.dialectName}' — skipped`);
+  return false;
+}
+
+/** The body of `SqlDriver#rebuildSqliteTablePatched`; the method's docblock there is its contract. */
+export async function rebuildSqliteTablePatched(this: Pick<SchemaSyncHost, 'applyDeclaredColumnDefault' | 'buildRebuiltColumn' | 'introspectColumns' | 'knex' | 'logger' | 'managedObjectFields' | 'managedObjectIndexes' | 'nowColumnDefault' | 'resolveTenantField' | 'syncTableIndexes'>, table: string, ents: ManagedDriftEntry[]): Promise<ManagedDriftEntry[]> {
+  const relax = new Set<string>();
+  const tighten = new Set<string>();
+  const drop = new Set<string>();
+  const dropDefault = new Set<string>();
+  // The entries this rebuild ACTS on, filled by the same pass that fills the
+  // four sets — deliberately not a second list of op types to keep in sync
+  // with the branches below. An entry is honoured if and only if one of those
+  // branches took it, so the returned set cannot drift from the work done.
+  const honoured: ManagedDriftEntry[] = [];
+  for (const e of ents) {
+    if (e.op.type === 'relax_not_null') relax.add(e.op.column);
+    else if (e.op.type === 'tighten_not_null') tighten.add(e.op.column);
+    else if (e.op.type === 'drop_column') drop.add(e.op.column);
+    else if (e.op.type === 'drop_column_default') dropDefault.add(e.op.column);
+    // Everything else is IGNORED here and must be reported as such (#11722):
+    // widen/narrow varchar (SQLite ignores declared length — nothing to do),
+    // `manual_column_type_change` (no reconciler arm on ANY dialect, by
+    // decision), and any column op added later, which lands in this branch by
+    // default rather than being silently absorbed into `honoured`.
+    else continue;
+    honoured.push(e);
+  }
+
+  const physical = await this.introspectColumns(table);
+  const kept = physical.filter((c) => !drop.has(c.name));
+  const keptNames = kept.map((c) => c.name);
+  const fields = this.managedObjectFields.get(table) ?? {};
+  const tmp = `__os_mig_${table}`;
+
+  // FK enforcement must be toggled OUTSIDE the transaction (SQLite ignores
+  // the PRAGMA inside one). Off during the swap so the rename doesn't trip
+  // any dangling references mid-flight.
+  await this.knex.raw('PRAGMA foreign_keys = OFF');
+  try {
+    await this.knex.transaction(async (trx) => {
+      await trx.schema.dropTableIfExists(tmp);
+      await trx.schema.createTable(tmp, (t) => {
+        for (const c of kept) {
+          const col = this.buildRebuiltColumn(t, c);
+          if (!col) continue;
+          const nullable = relax.has(c.name) ? true : tighten.has(c.name) ? false : c.nullable;
+          if (!nullable && c.name !== 'id') col.notNullable();
+          if (c.name === 'created_at' || c.name === 'updated_at') {
+            // #11321: the SAME canonical default {@link createAuditTimestampColumn}
+            // emits, not `knex.fn.now()`. This method is SQLite-only (see the
+            // `isSqlite` branch in `applyMigrationEntries`), where
+            // `knex.fn.now()` is the zone-naive `CURRENT_TIMESTAMP` — so
+            // re-emitting it here would silently REVERT a table that was
+            // created with the canonical default the moment any unrelated
+            // drift (a relaxed NOT NULL, a dropped column) triggered a
+            // rebuild. A rebuild must hand back the column `initObjects`
+            // would have built.
+            col.defaultTo(this.nowColumnDefault('datetime'));
+          } else if (!dropDefault.has(c.name)) {
+            // Re-emit the METADATA-declared default. The rebuild dropped the
+            // original table, so a column whose default is not restated here
+            // comes back without one — which is precisely what a
+            // `drop_column_default` op wants, and precisely what a
+            // `defaultValue: 'NOW()'` sibling must not suffer.
+            const f = (fields as Record<string, any>)[c.name];
+            if (f) this.applyDeclaredColumnDefault(col, f, f.type || 'string');
+          }
+        }
+      });
+      const colList = keptNames.map((n) => `"${n}"`).join(', ');
+      await trx.raw(`INSERT INTO "${tmp}" (${colList}) SELECT ${colList} FROM "${table}"`);
+      await trx.schema.dropTable(table);
+      await trx.schema.renameTable(tmp, table);
+    });
+  } finally {
+    await this.knex.raw('PRAGMA foreign_keys = ON');
+  }
+
+  // Recreate unique constraints + declared indexes from metadata. The rebuild
+  // dropped the original table, so every index went with it — this is a fresh
+  // materialization, and it must produce the SAME constraints as
+  // `initObjects` would. It used to inline its own `uniq_<table>_<col>`
+  // single-column DDL, which is how a tenant-scoped field could silently
+  // regain a global unique index after any drift rebuild (#3696); both paths
+  // now share {@link syncTableIndexes}.
+  try {
+    const keptSet = new Set(keptNames);
+    await this.syncTableIndexes(
+      table,
+      fields,
+      this.managedObjectIndexes.get(table),
+      this.resolveTenantField(table),
+      keptSet,
+    );
+  } catch (e: any) {
+    this.logger.warn(`[schema-drift] could not fully recreate indexes for '${table}' after rebuild`, e?.message ?? e);
+  }
+
+  return honoured;
+}