## What
A relation with `onDelete: Cascade | SetNull` whose child FK column has
no index makes every parent delete fire a cascade that sequentially
scans the whole child table. That has shipped three times recently and
had to be fixed after the fact (#4554 `ProjectAlert.channelId`, #4555
`EnvironmentVariableValue.valueReferenceId`, #4588
`PersonalAccessToken.userId`).
This adds a schema-aware CI guard that catches the next one before it
merges.
## How
`apps/webapp/scripts/fkCascadeIndexGuard.ts` parses both Prisma schemas
(`@trigger.dev/database`, `@internal/run-ops-database`) and flags any
`onDelete: Cascade | SetNull` relation whose leading FK scalar is not
the leading column of some index (`@@index` / `@@unique` / `@@id` /
field-level `@id`/`@unique`) on the child model. A leading FK column
lets the cascade's `WHERE fk = $1` use the index instead of a seq scan.
It is modeled on the existing `runOpsLegacyGuard` (same `--check` gate,
same baseline-regenerate pattern), and it is lighter: it only reads
`schema.prisma` as text, so its CI job needs no Prisma client generation
and no raised heap.
## Why a baseline, not a hard rule
Not every unindexed cascade FK is a live bug. When the parent is only
ever soft-deleted, the cascade never fires, so the missing index is
harmless. Hard vs soft delete lives in application code
(`parent.delete()` vs `parent.update({ deletedAt })`), not in the
schema, and a `deletedAt` column proves neither direction. So the guard
makes no such judgment: it flags every unindexed cascade FK uniformly
and carries a baseline of the 72 currently-accepted cases. Only
violations **not** in the baseline fail `--check`.
The value is the forcing function: a newly added cascade FK stops CI and
makes the author answer "is the parent ever hard-deleted?" Add the index
if yes; regenerate the baseline with a reason if no.
## Wiring
- `apps/webapp/package.json`: `guard:fk-cascade-index` script
(regenerate with no args, gate with `-- --check`).
- `.github/workflows/fk-cascade-guard.yml`: the reusable workflow.
- `.github/workflows/pr_checks.yml`: runs on webapp-affecting changes,
aggregated into `all-checks`.
## Verification
- The three already-fixed columns are correctly seen as indexed (absent
from the baseline).
- `--check` passes on the current schemas (72 baselined, 0 new).
- A synthetic new unindexed cascade FK fails with exit 1 and an
actionable message.
- Adding `@@index([fk])`, or a composite leading with the FK, clears it.
No false positives.
- `oxfmt` and `oxlint` clean on the new script.
## Rollback
Pure tooling addition, no runtime code, no schema or data change. Revert
to remove.
Eric Allam
4c21af8669