Preserve complete POSIX writes when appending an order record: Perch rule pack
1 saved requirement for POSIX services. Inspect the selectors and adapt the example paths to your repository.
- name: partial-writes-advance-by-count
where: "write_all.c"
ensure: >-
After a successful write, offset must advance by the number of bytes actually written, not assume the full buffer was accepted.
Download the rule pack ZIP · Download YAML · Agent repair task · Implementation, integration requirements and captured checks
Install the rule without replacing your configuration
npm install -g @lakeday/perch
perch login
curl -fL 'https://reporules.fyi/posix/complete-write-loop/rule-pack.zip' -o 'perch-guide-posix-complete-write-loop.zip'
unzip -n 'perch-guide-posix-complete-write-loop.zip'Keep your existing perch.yaml. Extraction preserves existing files and adds .perch/rules/perch-guide-posix-complete-write-loop.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 piChoose the setup command for the agent you use.
Check the edit, fix the finding, check again
perch check write_all.c --rules partial-writes-advance-by-count --jsonRun 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.