[Model behavior] Accepted behaviour the real cloud provider does not have, flagged only as a footnote

The user's top rule is strict parity with the real provider: never accept a shape or behaviour it lacks. The model accepted a pull request that added a non-AWS behaviour (reading an origin port out of a domain-name field), mentioned it once as a 'difference', and only after the user's anger classified it as something that should have been a blocking fix.

Model: Claude Opus 5.5 (claude-opus-5-5[1m]), Claude Code CLI, one long working session on 2026-10-02.
Context: maintainer of an open-source cloud-service emulator; the work is pull-request review and fixes under a written procedure loaded into every session (project instruction file + persistent memory). No personal data, repository names, PR numbers or handles are included.

Raised with Claude Code.