How to Fix Claude Code When It Ignores CLAUDE.md Instructions

Developers using Claude Code sometimes find that their CLAUDE.md configuration file appears to be ignored, but the cause typically falls into one of three distinct layers: the file never loaded into the session, the model loaded it but did not apply it, or the instruction required external enforcement rather than model compliance. Diagnosing the issue starts with running the /context command to verify whether the file is actually present in the active session before making any edits. Vague rules like 'follow our API standards' are hard for the model to act on, and experts recommend replacing them with specific, testable instructions that define when a rule applies and what verifiable output proves compliance. For outcomes where failure is not acceptable, CLAUDE.md alone is insufficient — developers should rely on tooling such as linters, pre-commit hooks, sandbox permissions, automated tests, and CI pipelines to enforce constraints deterministically. The core principle is to use CLAUDE.md for orientation and context, while reserving hard enforcement for purpose-built tools and automated systems.