fix: bulk action global validation ordering and before_action? support

[nallwhy]

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• I accept the AI Policy, or AI was not used in the creation of this PR.
• Bug fixes include regression tests
• Chores
• Documentation changes
• Features include unit/acceptance tests
• Refactoring
• Update dependencies

Summary

• Fix global validation/change ordering in bulk_create, bulk_update, and bulk_destroy to match non-bulk behavior
• Add before_action? support for validations in the bulk create and bulk update pipelines

Problem

Two bugs across all bulk action modules (Ash.Actions.Create.Bulk, Ash.Actions.Update.Bulk, Ash.Actions.Destroy.Bulk):

1. Reversed ordering: Global validations were concatenated before global changes in pre_template_all_changes.
   The non-bulk path runs action changes + global changes first, then global validations,
   but the bulk path was concatenating in action changes → global validations → global changes order.

2. before_action? ignored: The before_action? flag on validations was completely ignored in the bulk path, causing them to run inline.
   The non-bulk path checks this flag and defers via Ash.Changeset.before_action/2,
   but the bulk run_action_changes never read this field.

Changes

lib/ash/actions/create/bulk.ex

• pre_template_all_changes: Reorder concat so global changes come before global validations
• run_action_changes: Check before_action? on validations; when true, register via Ash.Changeset.before_action/2 instead of running inline
• Extract inline validation logic into run_bulk_validation/6
• Simplify validation.message error handling to reduce duplication

lib/ash/actions/update/bulk.ex

• pre_template_all_changes: Same ordering fix as bulk_create
• run_action_changes: Add before_action? support for validations
• Simplify validation.message error handling in validate_batch_non_atomically

lib/ash/actions/destroy/bulk.ex

• pre_template_all_changes: Same ordering fix as bulk_create
• before_action? support inherited via delegation to Ash.Actions.Update.Bulk.run_action_changes

[Copilot]

Pull request overview

Fixes bulk create’s change/validation pipeline so it matches the non-bulk for_create behavior, including honoring before_action? validations.

Changes:

• Reorders global changes vs global validations in bulk_create so global changes run before global validations.
• Adds before_action? support for bulk validations by registering them via Ash.Changeset.before_action/2.
• Adds regression tests covering both ordering and before_action? behavior for global validations.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
lib/ash/actions/create/bulk.ex	Fixes global change/validation ordering and defers before_action? validations via changeset hooks (with extracted helper).
test/actions/bulk/bulk_create_test.exs	Adds coverage to ensure global changes precede global validations and before_action? validations behave like the non-bulk pipeline.

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[zachdaniel]

Can we separate these two changes? The reason for that is that before_action can't necessarily be supported in bulk_update actions depending on how they are running and it would be nice to consider these separately. Thanks!