feat(BA-6628): conditional-bulk repository primitives

[jopemachine]

Summary

Generic, domain-agnostic repository primitives for gated bulk writes, split out of #12426 (BA-6626) so app_config_fragment — and future domains — build on them. No app_config-specific code.

• repositories/base: ConditionalCreator / ConditionalUpdater / ConditionalPurger and BulkConditional{Creator,Updater,Purger} — a write spec paired with an only_if existence gate.
• WriteOps.bulk_conditional_create_partial / _update_partial / _purge_partial — each item runs in its own savepoint for partial success (gate-rejected / missing / failed items reported per-item; the rest proceed). Implemented directly in WriteOps with private _update_one/_purge_one row helpers (not delegating to the standalone execute_* functions).
• Repository errors ConditionalWriteNotAllowed / ConditionalWriteTargetNotFound.
• Ops-provider unit tests.

📚 Stacked PRs

Part of the AppConfigFragment / AppConfig stack under BEP-1052 (epic BA-5781). Merge in order:

1. ✅ feat(BA-6552): add app_config_fragments DB model and Alembic migration #12306 — feat(BA-6552): app_config_fragments DB model and Alembic migration
2. ✅ feat(BA-6553): add app_config_fragments repository layer #12307 — feat(BA-6553): repository layer
3. ✅ refactor(BA-6619): consolidate AppConfigScopeType into common.data (single definition) #12403 — refactor(BA-6619): consolidate AppConfigScopeType into common.data
4. ✅ refactor(BA-6620): ExistsQuerier ops primitive + AppConfigAllowList.exists #12405 — refactor(BA-6620): ExistsQuerier + AppConfigAllowList.exists
5. ✅ feat(BA-6554): add app_config_fragment service layer #12358 — feat(BA-6554): AppConfigFragment service layer
6. 👉 feat(BA-6628): conditional-bulk repository primitives #12429 — feat(BA-6628): conditional-bulk repository primitives ← you are here
7. feat(BA-6626): app_config_fragment bulk repository layer #12426 — feat(BA-6626): app_config_fragment bulk repository layer
8. feat(BA-6618): app_config_fragment bulk CRUD service layer #12401 — feat(BA-6618): AppConfigFragment bulk CRUD service layer
9. feat(BA-6555): add app_config service layer #12359 — feat(BA-6555): app_config service layer
10. feat(BA-6556): AppConfig REST v2 API (raw fragments and merged read/update) #12377 — feat(BA-6556): AppConfig REST v2 API

[Copilot]

Pull request overview

This PR adds generic, domain-agnostic repository primitives for gated bulk writes as step 6 of the AppConfigFragment/AppConfig stack (BEP-1052). It introduces Conditional{Creator,Updater,Purger} (a write spec paired with an only_if existence gate) and their BulkConditional* bundles, plus three WriteOps.bulk_conditional_*_partial methods that isolate each item in its own savepoint so gate-rejected, missing, or failed items are reported per-item while the rest proceed. The update/purge ops paths are refactored to delegate to new private _update_one/_purge_one helpers. Two repository errors (ConditionalWriteNotAllowed, ConditionalWriteTargetNotFound) and ops-provider unit tests round it out.

Changes:

• New conditional/bulk-conditional dataclasses in repositories/base for create/update/purge.
• WriteOps.bulk_conditional_*_partial methods with per-item savepoint isolation, plus _update_one/_purge_one extracted from the standalone execute_* functions.
• New ConditionalWriteNotAllowed / ConditionalWriteTargetNotFound errors and ops-provider tests.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/ai/backend/manager/repositories/base/creator.py	Adds ConditionalCreator/BulkConditionalCreator; docstring misstates semantics and references a non-existent function.
src/ai/backend/manager/repositories/base/updater.py	Adds ConditionalUpdater/BulkConditionalUpdater; docstring misstates semantics and method name.
src/ai/backend/manager/repositories/base/purger.py	Adds ConditionalPurger/BulkConditionalPurger; docstring misstates semantics and method name.
src/ai/backend/manager/repositories/base/init.py	Exports the new conditional/bulk-conditional types.
src/ai/backend/manager/repositories/ops/base/provider.py	Adds the three bulk_conditional_*_partial methods and _update_one/_purge_one helpers; update/purge now delegate to them.
src/ai/backend/manager/errors/repository.py	Adds ConditionalWriteNotAllowed / ConditionalWriteTargetNotFound errors.
tests/unit/manager/repositories/ops/test_provider.py	Adds tests for the three conditional-bulk ops (all-pass, partial gate failure, empty, missing row).
changes/12429.misc.md	Adds the changelog entry.

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