## Why
Fast instance commands run in the ArgoCD **PreSync** hook, before the
new pods roll. A bulk `UPDATE`/`INSERT`/`DELETE` held in the **same
transaction** as an `ADD COLUMN`/`ALTER` keeps an `ACCESS EXCLUSIVE`
lock on the table for the whole write, blocking every read of it. That
is what froze prod during the 2.13 `isUIReadOnly → isUIEditable` rename
— a bulk `UPDATE "fieldMetadata"` inside the same `up()` transaction as
the `ADD COLUMN`s → read timeouts → failed PreSync → aborted sync.
@charlesBochet already caught this exact pattern by hand on #21527
("data migration => make a slow instance command :)"). This turns that
manual review into something CI enforces.
## What
New oxlint rule **`twenty/no-data-mutation-in-fast-instance-command`**:
- Flags statement-leading `UPDATE`/`INSERT`/`DELETE`/`MERGE` passed to
`.query(...)` **inside `up()`** of a `*-instance-command-fast-*` file.
- Allows: schema DDL (`ALTER`/`CREATE`/`DROP`); `ON DELETE CASCADE` / a
column named `updatedAt` (not statement-leading, so never matched);
rollback DML in `down()`; and data migrations in **slow** commands'
`runDataMigration()`.
- The error message points the author straight at the slow-command
pattern.
Enabled as `error` in `twenty-server`.
## Grandfathering
Scoping to `up()` means **only one** existing file violates the rule:
the already-shipped 2.13 rename command. It's recorded complete in cloud
and must not be rewritten, so it's grandfathered with a documented
file-level `oxlint-disable` (the comment makes clear it's an exception,
not a precedent). The four other fast commands that contain DML keep
theirs in `down()` and are correctly unaffected.
## Tests
- 9 RuleTester cases — valid: DDL, FK cascade, `updatedAt`, `down()`
DML, slow-command DML, non-upgrade files; invalid:
`UPDATE`/`INSERT`/`DELETE` in `up()`.
- Verified end-to-end with oxlint: a throwaway violating file → 1 error;
all 141 upgrade-command files → 0 errors; full oxlint-rules suite
225/225; typecheck clean.
Part of the v2.13 deploy post-mortem follow-ups.
https://claude.ai/code/session_013Az1etaGyxWRRVhgjhPWeB
---
_Generated by [Claude
Code](https://claude.ai/code/session_013Az1etaGyxWRRVhgjhPWeB)_
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Co-authored-by: Claude <noreply@anthropic.com>
Félix Malfait
