fix(#4560): defaultValue runtime tokens never become a column DEFAULT

The SQL DDL passed any non-object `defaultValue` through to
`col.defaultTo(dv)`, so `Field.user({ defaultValue: 'current_user' })`
was created as `DEFAULT 'current_user'` and the DATABASE stamped the
literal token into every insert the engine had deliberately left unset
(system/anonymous writes) — a non-id in a `lookup('sys_user')` column,
found by #4551's dangling-reference audit.

Declare the token family once in `@objectstack/spec/data`
(`DEFAULT_VALUE_TOKENS` + predicates) so the engine's insert-time
resolution and the driver's DDL read one set: `'NOW()'` keeps its
driver-native default, every other token emits none, literals and
Expression envelopes are unchanged. Column-default emission is now a
single `applyDeclaredColumnDefault` shared by createColumn and the
SQLite table rebuild.

Existing databases are corrected through the managed schema-drift path:
a `default_mismatch` finding with a `safe` `drop_column_default` op
(ALTER … DROP DEFAULT on pg/mysql, table rebuild on SQLite, which now
re-materializes sibling defaults from metadata). Rows already holding
the bogus value are NOT rewritten — #4551's report-never-rewrite rule.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012C2cd7tL8QDoZ2QKN3djJ5

Author: claude

.changeset/ddl-runtime-token-default.md

@@ -0,0 +1,57 @@
+---
+"@objectstack/spec": patch
+"@objectstack/objectql": patch
+"@objectstack/driver-sql": patch
+---
+
+fix(driver-sql,spec,objectql): a `defaultValue` runtime token never becomes a column DEFAULT (#4560)
+
+`Field.user({ defaultValue: 'current_user' })` is resolved by the **engine**, at
+insert time, from the request's `ExecutionContext` — and with no authenticated
+user (system / anonymous writes: seed replay, package install, boot
+provisioning) `applyFieldDefaults` deliberately leaves the field **unset**
+rather than stamp a bogus owner.
+
+The SQL DDL had never heard of the token. `createColumn` passed any non-object
+`defaultValue` straight through to `col.defaultTo(dv)`, so the column was
+created as `DEFAULT 'current_user'` and the **database** overrode the engine's
+decision: every insert that omitted the field stored the literal string
+`current_user` in a `lookup('sys_user')` column — a value that is not any user's
+id. `?expand` resolves it to nothing, and on an owner / approver field it is a
+silent mis-attribution. Found by #4551's dangling-reference audit on its first
+run against a real boot; #4441's referential check could never have caught it,
+because it inspects the values a **caller** supplied and here nobody supplied
+one.
+
+**The token vocabulary is now declared once, in `@objectstack/spec/data`**
+(`DEFAULT_VALUE_TOKENS`, `isRuntimeDefaultToken`, `isNowDefaultToken`,
+`isCurrentUserDefaultToken`, `isAppResolvedDefaultToken`). The engine's
+insert-time resolution and the driver's DDL read the same set, which is the
+actual defect: `'NOW()'` was special-cased in the branch immediately above for
+precisely this reason, and `current_user` — the same convention family — simply
+had no entry anywhere the DDL could see. A token added to the set tomorrow is
+excluded from literal column DEFAULTs automatically, rather than leaking its own
+spelling into the database the way this one did.
+
+**DDL, in one place** (`applyDeclaredColumnDefault`, shared by column creation
+and the SQLite table rebuild):
+
+- `'NOW()'` → the driver-native canonical default, exactly as before;
+- any other runtime token → **no column default at all** (the engine owns it);
+- Expression envelopes (`{ dialect, source }`) → unchanged, no default;
+- a real literal → emitted verbatim, unchanged.
+
+**Existing databases carry the wrong DEFAULT**, so it is corrected through the
+managed schema-drift path (#2186) rather than a bespoke migration: a new
+`default_mismatch` finding with a `drop_column_default` op, categorised `safe`
+(the statement cannot fail and touches no rows). Dev boots with
+`autoMigrate: 'safe'` reconcile it automatically; everywhere else it is reported
+with an actionable hint and applied by `os migrate apply`. Postgres/MySQL use
+`ALTER COLUMN … DROP DEFAULT`; SQLite, which cannot alter a default in place,
+goes through the existing table rebuild — which now re-materialises every
+column's default from **metadata**, so a sibling `defaultValue: 'NOW()'` column
+keeps the default it always had instead of losing it to the rebuild.
+
+**Rows already holding the bogus value are NOT rewritten.** That is #4551's
+standing rule — report, never rewrite — so they stay visible to the
+dangling-reference audit for operators to resolve deliberately.

packages/objectql/src/engine-default-value-tokens.test.ts

@@ -0,0 +1,113 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * The engine half of the `defaultValue` runtime-token contract (#4560).
+ *
+ * `applyFieldDefaults` owns the `current_user` token: it stamps the acting
+ * user's id on insert, and with NO authenticated user (system / anonymous
+ * writes) it deliberately leaves the field UNSET rather than invent an owner.
+ *
+ * That "leave it unset" is only worth anything if nothing downstream fills the
+ * gap behind the engine's back — which is exactly what a SQL column
+ * `DEFAULT 'current_user'` did (#4560). These tests pin the engine side of the
+ * agreement, and that the token spelling it matches is the SPEC's
+ * (`DEFAULT_VALUE_TOKENS`), the same set a driver's DDL consults when deciding
+ * which `defaultValue`s may become a physical column DEFAULT.
+ */
+
+import { describe, it, expect, beforeEach } from 'vitest';
+import { ObjectQL } from './engine.js';
+import { DEFAULT_VALUE_TOKEN_CURRENT_USER } from '@objectstack/spec/data';
+
+function makeMemoryDriver() {
+  const stores = new Map<string, Map<string, Record<string, unknown>>>();
+  const storeFor = (obj: string) => {
+    let s = stores.get(obj);
+    if (!s) { s = new Map(); stores.set(obj, s); }
+    return s;
+  };
+  let nextId = 0;
+  const driver: any = {
+    name: 'memory', version: '0.0.0', supports: {} as any,
+    async connect() {}, async disconnect() {}, async checkHealth() { return true; },
+    async execute() { return null; },
+    async find(object: string) { return Array.from(storeFor(object).values()); },
+    findStream() { throw new Error('not implemented'); },
+    async findOne(object: string) { return storeFor(object).values().next().value ?? null; },
+    async create(object: string, data: Record<string, unknown>) {
+      nextId += 1;
+      const id = (data.id as string) ?? `r_${nextId}`;
+      const row = { ...data, id };
+      storeFor(object).set(id, row);
+      return row;
+    },
+    async update() { return null; },
+    async upsert(object: string, data: Record<string, unknown>) { return this.create(object, data); },
+    async delete() { return true; },
+    async count(object: string) { return storeFor(object).size; },
+    async bulkCreate(object: string, rows: Record<string, unknown>[]) {
+      return Promise.all(rows.map((r) => this.create(object, r)));
+    },
+    async bulkUpdate() { return []; },
+    async bulkDelete() {},
+    async updateMany() { return 0; },
+    async beginTransaction() { return { commit: async () => {}, rollback: async () => {} }; },
+    async commit() {}, async rollback() {},
+  };
+  return { driver, stores };
+}
+
+const owned = {
+  name: 'tok_doc',
+  label: 'Doc',
+  fields: {
+    id: { name: 'id', label: 'ID', type: 'text' as const, primaryKey: true },
+    title: { name: 'title', label: 'Title', type: 'text' as const },
+    owner: {
+      name: 'owner', label: 'Owner', type: 'user' as const,
+      reference: 'sys_user', defaultValue: DEFAULT_VALUE_TOKEN_CURRENT_USER,
+    },
+  },
+};
+
+describe('[#4560] the `current_user` defaultValue token is engine-owned', () => {
+  let engine: ObjectQL;
+
+  beforeEach(async () => {
+    engine = new ObjectQL();
+    engine.registerDriver(makeMemoryDriver().driver, true);
+    await engine.init();
+    engine.registry.registerObject(owned as any);
+  });
+
+  it('stamps the acting user id on an authenticated insert', async () => {
+    const row: any = await engine.insert('tok_doc', { title: 'A' }, { context: { userId: 'usr_7' } } as any);
+    expect(row.owner).toBe('usr_7');
+  });
+
+  it('leaves the field UNSET on a system/anonymous insert — never the literal token', async () => {
+    // The seed-replay / package-install / boot-provisioning shape. This is the
+    // decision a column DEFAULT used to override, writing the literal string
+    // `current_user` into a lookup('sys_user') column (#4560).
+    const row: any = await engine.insert('tok_doc', { title: 'B' }, { context: { isSystem: true } } as any);
+    expect(row.owner).toBeUndefined();
+    expect(row.owner).not.toBe('current_user');
+  });
+
+  it('an explicit null is treated as "not supplied" and still resolves the token (#2706)', async () => {
+    const row: any = await engine.insert('tok_doc', { title: 'C', owner: null }, { context: { userId: 'usr_9' } } as any);
+    expect(row.owner).toBe('usr_9');
+  });
+
+  it('a NEAR-MISS spelling is a literal, not a token — it is an authoring error, not an alias', async () => {
+    engine.registry.registerObject({
+      ...owned,
+      name: 'tok_typo',
+      fields: { ...owned.fields, owner: { ...owned.fields.owner, defaultValue: 'CURRENT_USER' } },
+    } as any);
+    const row: any = await engine.insert('tok_typo', { title: 'D' }, { context: { userId: 'usr_1' } } as any);
+    // Deliberately NOT resolved: widening the match would make a genuinely
+    // intended literal unstorable. Lint catches the typo at authoring time.
+    expect(row.owner).toBe('CURRENT_USER');
+  });
+});

packages/objectql/src/engine.ts

@@ -17,7 +17,7 @@ import {
   type DroppedFieldsEvent
 } from '@objectstack/spec/data';
 import type { WriteObservabilityOptions } from '@objectstack/spec/contracts';
-import { parseAutonumberFormat, renderAutonumber, missingFieldValues, isTenancyDisabled, FILE_REFERENCE_TYPES, REFERENCE_VALUE_TYPES, referenceTargetOf, isFileIdToken, RAW_FILE_VALUES_CONTEXT_KEY } from '@objectstack/spec/data';
+import { parseAutonumberFormat, renderAutonumber, missingFieldValues, isTenancyDisabled, FILE_REFERENCE_TYPES, REFERENCE_VALUE_TYPES, referenceTargetOf, isFileIdToken, RAW_FILE_VALUES_CONTEXT_KEY, isCurrentUserDefaultToken } from '@objectstack/spec/data';
 import {
   DATA_MIGRATION_FLAG_OBJECT,
   FILE_REFERENCES_MIGRATION_ID,
@@ -1379,13 +1379,20 @@ export class ObjectQL implements IObjectQLEngine {
             object, field: f.name, error: result.error,
           });
         }
-      } else if (dv === 'current_user') {
+      } else if (isCurrentUserDefaultToken(dv)) {
         // `current_user` token → the acting user's id at insert time. Declarative
         // counterpart to writing a beforeInsert hook; mirrors the 'NOW()' string
         // convention and is resolved app-side per request (driver-agnostic), so
         // `Field.user({ defaultValue: 'current_user' })` auto-fills the actor.
         // When there is no authenticated user (system/anonymous), leave it unset
         // and let required-validation decide — never stamp a bogus owner.
+        //
+        // The token spelling comes from `@objectstack/spec/data`
+        // (`DEFAULT_VALUE_TOKENS`), the one place the family is declared, so a
+        // driver's DDL reads the SAME set when deciding which `defaultValue`s
+        // may become a physical column DEFAULT. When the two sides disagreed,
+        // SQL emitted `DEFAULT 'current_user'` and the DATABASE overrode the
+        // "leave it unset" decision below with a literal non-id (#4560).
         if (execCtx?.userId != null) out[f.name] = String(execCtx.userId);
       } else {
         out[f.name] = dv;

packages/plugins/driver-sql/src/schema-drift.ts

@@ -30,7 +30,7 @@
 
 import { createHash } from 'node:crypto';
 
-import { isGlobalUnique, isUniqueDeclared } from '@objectstack/spec/data';
+import { isAppResolvedDefaultToken, isGlobalUnique, isUniqueDeclared } from '@objectstack/spec/data';
 import type { SchemaDiffEntry } from '@objectstack/spec/shared';
 
 export type SqlDialectName = 'sqlite' | 'postgres' | 'mysql' | 'unknown';
@@ -50,6 +50,19 @@ export type DriftOp =
   | { type: 'widen_varchar'; table: string; column: string; to: number; from?: number }
   | { type: 'narrow_varchar'; table: string; column: string; to: number; from?: number }
   | { type: 'drop_column'; table: string; column: string }
+  /**
+   * Strip a column DEFAULT metadata never asked for (#4560).
+   *
+   * Today's only source is a `defaultValue` runtime token that a pre-fix build
+   * emitted as a literal (`DEFAULT 'current_user'`), so every insert that
+   * omitted the field got the token's own spelling instead of the engine's
+   * deliberate "leave it unset". Dropping it cannot fail and cannot lose data —
+   * stored rows keep whatever they hold; only FUTURE omitted inserts change,
+   * from a bogus literal to NULL. Rows already carrying the bogus value are NOT
+   * rewritten: they stay visible to the dangling-reference audit (#4551), whose
+   * standing rule is report, never rewrite.
+   */
+  | { type: 'drop_column_default'; table: string; column: string }
   /**
    * Retire the legacy platform-wide UNIQUE index on a now-tenant-scoped field
    * and put the composite `(tenantField, field)` in its place (#3696). The two
@@ -196,6 +209,13 @@ export interface PhysicalColumn {
   type: string;
   nullable: boolean;
   maxLength?: number;
+  /**
+   * The column's raw DEFAULT as the dialect reports it (knex `columnInfo`), or
+   * `null`/`undefined` when it has none. Dialect-decorated — SQLite and Postgres
+   * quote a string literal and Postgres appends a `::type` cast — so compare it
+   * through {@link physicalDefaultIsToken}, never with `===`.
+   */
+  defaultValue?: unknown;
 }
 
 /** Minimal shape of a metadata field definition. */
@@ -206,6 +226,35 @@ export interface FieldDef {
   maxLength?: number;
   /** ADR-0113: the explicit physical constraint — nullability drift reads THIS, not `required`. */
   storage?: { notNull?: boolean };
+  /**
+   * The declared default. Only consulted for the runtime-token dimension
+   * (#4560): a token is an instruction, so it must never appear as a physical
+   * column DEFAULT. Literal defaults are deliberately NOT diffed — a hand-edited
+   * DEFAULT on a column is a DBA's business, and reporting every one of them
+   * would drown the plan the same way undeclared indexes would.
+   */
+  defaultValue?: unknown;
+}
+
+/**
+ * Does the physical column DEFAULT literally spell out `token`?
+ *
+ * Each dialect decorates the literal it reports differently — SQLite
+ * `'current_user'`, Postgres `'current_user'::character varying`, MySQL a bare
+ * `current_user` — so the raw string is stripped of one layer of quoting and of
+ * a trailing cast before comparing. Deliberately EXACT after that: this is the
+ * fingerprint of a DEFAULT the platform itself emitted from a token spelling,
+ * and matching loosely would let it drop a default that merely resembles one.
+ */
+export function physicalDefaultIsToken(raw: unknown, token: string): boolean {
+  if (typeof raw !== 'string') return false;
+  let s = raw.trim();
+  const cast = s.indexOf('::');
+  if (cast > 0) s = s.slice(0, cast).trim();
+  if (s.length >= 2 && ((s.startsWith("'") && s.endsWith("'")) || (s.startsWith('"') && s.endsWith('"')))) {
+    s = s.slice(1, -1);
+  }
+  return s === token;
 }
 
 /**
@@ -305,6 +354,36 @@ export function diffManagedTable(args: {
       });
     }
 
+    // ── runtime-token column DEFAULT (#4560) ──────────
+    // A `defaultValue` the APPLICATION layer owns (`current_user`) must leave
+    // the column with no DEFAULT at all. A build that predated the token family
+    // passed it through to `col.defaultTo(...)`, so the database now supplies
+    // the token's own spelling — a literal `'current_user'` in a
+    // `lookup('sys_user')` column — for exactly the writes the engine
+    // deliberately left unset. Detected here rather than fixed inline so it
+    // travels the same plan/apply road as every other divergence.
+    if (isAppResolvedDefaultToken(field.defaultValue) && physicalDefaultIsToken(col.defaultValue, field.defaultValue)) {
+      out.push({
+        kind: 'default_mismatch',
+        remoteName: table,
+        table,
+        column: fieldName,
+        expected: '(no column default)',
+        actual: `DEFAULT '${field.defaultValue}'`,
+        severity: 'warning',
+        // Pure removal: stored rows are untouched and the statement cannot
+        // fail, so dev auto-reconcile is welcome to apply it unattended.
+        category: 'safe',
+        op: { type: 'drop_column_default', table, column: fieldName },
+        message:
+          `${table}.${fieldName}: the column carries DEFAULT '${field.defaultValue}', but ` +
+          `'${field.defaultValue}' is a runtime token the engine resolves per write — the database ` +
+          `has been stamping the literal token into every insert that omitted the field (#4560). ` +
+          `Dropping the default is non-destructive: run "os migrate apply". Rows already holding ` +
+          `'${field.defaultValue}' are NOT rewritten — the dangling-reference audit reports them.`,
+      });
+    }
+
     // ── varchar length (only where the dialect enforces it) ──────────
     if (
       enforcesVarcharLength(dialect) &&