Source: https://reporules.fyi/aspnet-core/optimistic-concurrency/

# Return a conflict when EF Core detects a stale order edit: Perch rule pack

1 saved requirement for ASP.NET Core. Inspect the selectors and adapt the example paths to your repository.

```
- name: stale-update-is-not-success
  where: "Services/CancelOrder.cs"
  ensure: >-
    Apply must return false when SaveChangesAsync throws DbUpdateConcurrencyException. A stale write must not be reported as successful.
```

[Download the rule pack ZIP](https://reporules.fyi/aspnet-core/optimistic-concurrency/rule-pack.zip) · [Download YAML](https://reporules.fyi/aspnet-core/optimistic-concurrency/rules.yaml) · [Agent repair task](https://reporules.fyi/aspnet-core/optimistic-concurrency/agent-task.txt) · [Implementation, integration requirements and captured checks](https://frameworkrecipes.dev/aspnet-core/optimistic-concurrency/)

## Install the rule without replacing your configuration

```
npm install -g @lakeday/perch
perch login
curl -fL 'https://reporules.fyi/aspnet-core/optimistic-concurrency/rule-pack.zip' -o 'perch-guide-aspnet-core-optimistic-concurrency.zip'
unzip -n 'perch-guide-aspnet-core-optimistic-concurrency.zip'
```

Keep your existing perch.yaml. Extraction preserves existing files and adds .perch/rules/perch-guide-aspnet-core-optimistic-concurrency.yaml. Review each where selector before running a check on your application.

## Configure your coding agent

```
perch setup claude-code
perch setup codex
perch setup cursor
perch setup pi
```

Choose the setup command for the agent you use.

## Check the edit, fix the finding, check again

```
perch check Services/CancelOrder.cs --rules stale-update-is-not-success --json
```

Run the check after an agent edit. Read the finding and affected code, repair the implementation, and repeat the identical command. Keep the application regression tests as separate gates.

Exit 3 means a finding. Exit 1 or 2 means the check did not complete. A pass does not prove application correctness. Fresh judgments can vary; unchanged requests reuse cached answers. Relevant source is sent to the configured model service.

[Pack manifest and SHA-256 hash](https://reporules.fyi/aspnet-core/optimistic-concurrency/rule-pack.json) · [Pack README](https://reporules.fyi/aspnet-core/optimistic-concurrency/rule-pack-readme.md)

**Repo Rules**

Requirements that stay in the repo.

Published by Perch · © 2026 Verglas LLC. Repo Rules is a Perch publication.

Perch’s MIT license covers the CLI; hosted model analysis is a paid service. Relevant source is sent to the configured model service.

[Perch CLI MIT license](https://github.com/lakeday-org/perch/blob/main/LICENSE) · [Article text](https://reporules.fyi/aspnet-core/optimistic-concurrency/index.md) · [Resource index](https://reporules.fyi/llms.txt)