[Feature Request] Support CLAUDE.md.d/ directory for multi-file configuration at same scope level

Bug Description

Feature Request: CLAUDE.md.d/ Directory Support

Multi-file config at same scope level

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Currently, Claude Code supports one CLAUDE.md file per directory level. I'd like to propose supporting a CLAUDE.md.d/ folder alongside it, where multiple markdown files are loaded and unioned — similar to how .conf.d/ directories work in Linux (e.g. /etc/nginx/conf.d/, systemd drop-ins, etc.).

The Problem with a Single File per Level

As a project matures, a single CLAUDE.md at the project root grows to cover multiple distinct concerns — coding conventions, architecture decisions, toolchain rules, git workflow, testing standards. These are logically separate but currently forced into one file. This makes the file harder to maintain, harder to audit for drift, and harder to assign ownership in a team setting.

What the .conf.d Pattern Would Enable

my-app/CLAUDE.md                        # unchanged, still supported
my-app/CLAUDE.md.d/
    01-coding-style.md
    02-architecture.md
    03-git-workflow.md
    04-testing.md

All files in the folder get loaded and unioned at that scope level, in filename order. The numeric prefix (a common .conf.d convention) gives explicit control over precedence within the same level when needed.

Why This Is Better than Just Splitting into Subdirectories

Subdirectory CLAUDE.md files are a different axis — they narrow scope (only loaded when working in that subtree). The .conf.d pattern splits by concern at the same scope. Both are useful and complementary; they solve different problems.

Additional Benefits

• Team ownership: different team members or teams can own different files
• Cleaner git history: changes to testing rules don't show up in the same file as architecture notes
• Easier auditing: you can review one concern at a time
• Adherence: stays under the ~150 line threshold per file without sacrificing coverage

The mental model is already well understood by developers familiar with Linux config systems, so adoption friction would be low.

Environment Info

• Platform: darwin
• Terminal: iTerm.app
• Version: 2.1.131
• Feedback ID: 4f6cd1de-43a6-4fb9-bdee-805fec5e24a7

Errors

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