Path-based rules (.claude/rules/ with paths: frontmatter) are not loaded on Write tool — only on Read

Problem

Path-based rules defined in .claude/rules/ with a paths: frontmatter are only injected into context when Claude reads a file matching the pattern. They are not injected when Claude writes/creates a file matching the same pattern.

This means that any rule targeting file creation conventions (e.g., "add a specific header to new .md files", "enforce a comment on new .ts files") is silently ignored when a new file is created, because Claude never sees the rule at the time of writing.

Reproduction Steps

Setup

1. Create a path-based rule .claude/rules/testing/instructions/create.md:

---
paths:
  - "**/*.md"
---
# Create Instructions
When **creating** a new .md file, ALWAYS add `# created` as the very first line.

1. Create a complementary rule .claude/rules/testing/instructions/update.md:

---
paths:
  - "**/*.md"
---
# Update Instructions
When **editing** an existing .md file, ALWAYS replace the first line with `# updated`.

Test 1 — Write (rules NOT loaded)

Ask Claude: _"Create a file toto.md with content toto"_

Result: Claude creates toto.md with just toto. The create.md rule was never injected — Claude had no knowledge of the "add # created" instruction.

Test 2 — Read (rules loaded)

Ask Claude: _"Edit toto.md, replace content with 1"_

Claude calls Read on toto.md first (required before Edit). This time, the system-reminder injects both create.md and update.md rules. Claude sees the update instruction and correctly applies # updated as the first line.

Test 3 — Proof the rule existed

The create.md rule was valid and correctly configured — it just was never surfaced to Claude during the Write operation. The same rule loads perfectly when Read is called on any matching .md file.

Expected Behavior

Path-based rules matching the target file path should be injected into context for all file operations — Write, Edit, MultiEdit, and Read — not just Read.

When Claude creates a new file matching **/*.md, any rule with paths: ["**/*.md"] should be visible before or during the Write, so Claude can apply the instructions (like adding a required header).

Current Workaround

We implemented a PostToolUse hook on Write that injects an additionalContext message asking Claude to Read the file it just created, which forces rule loading. Claude then applies a corrective Edit if rules require it.

{
  "hooks": {
    "PostToolUse": [
      {
        "matcher": "Write",
        "hooks": [
          {
            "type": "command",
            "command": "bash hooks/post-write-rules-loader.sh"
          }
        ]
      }
    ]
  }
}

This works (tested with both .md and .ts path-based rules), but it's a 3-step workaround (Write → Read → Edit) for what should be a 1-step operation (Write with rules already in context).

Why This Matters

Path-based rules are the primary mechanism for granular, targeted instructions by file type. The most critical use case — enforcing conventions on file creation — is the exact scenario where they don't work. This forces users to either:

• Duplicate all creation rules into CLAUDE.md (losing the granularity benefit of path-based rules)
• Implement PostToolUse hooks as workarounds (adds complexity and an extra round-trip)
• Accept that creation rules are silently ignored

Environment

• Claude Code CLI
• macOS (Apple Silicon)
• Rules with paths: frontmatter in .claude/rules/