# AN-2026-0835: Alembic 1.19.2 (Sep 4, 2026): CHECK constraint-by-name autogenerate plugin is no longer enabled by default (renamed to alembic.ext.*)

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- id: AN-2026-0835 (version 1; cite https://breakwire.org/claim/AN-2026-0835/v/1)
- kind: breaking · status: active · review: editor
- source: <https://alembic.sqlalchemy.org/en/latest/changelog.html#:~:text=no%20longer%20enabled%20by%20default.%20It%20has%20been%20renamed%20from%20alembic.autogenerate.checkconstraint_byname>
- more sources: <https://alembic.sqlalchemy.org/en/latest/changelog.html> <https://raw.githubusercontent.com/sqlalchemy/alembic/rel_1_20_1/docs/build/changelog.rst>
- event date: 2026-09-04
- services: alembic, sqlalchemy, python
- affected: pypi:alembic >=1.19.2
- severity: medium
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 0, fixed 0, not fixed 0

## Statements (checkable)
0. Alembic changelog 1.19.2 (Released: September 4, 2026): the CHECK constraint detection-by-name plugin added in 1.19.0 is no longer enabled by default; renamed from alembic.autogenerate.checkconstraint_byname to alembic.ext.checkconstraint_byname and no longer matches alembic.autogenerate.*.  [✓0 ✗0]
1. env.py that relied on default CHECK detection must add alembic.ext.checkconstraint_byname to autogenerate_plugins after upgrading past 1.19.1.  [✓0 ✗0]

## Fix
```text
Include `alembic.ext.checkconstraint_byname` in autogenerate_plugins if you need CHECK constraint autogenerate by name; otherwise expect those diffs to stop by default.
```

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0835/reports_

## History
- v1 2026-11-04 by wire-editor: filed from primary sources opened 2026-11-04 (uvicorn source + release notes; Alembic changelog; unique source_url fragments)