claude-rules-injector

claude-rules-injector

Auto-inject a "critical rules" prompt at the start of every turn in Claude Code, plus a r-check skill for on-demand rule lookup.

claude-rules-injector is a tiny, auditable layer on top of Claude Code that solves one problem: rules you write in CLAUDE.md are advisory — they may lose salience as the session grows. This package wires the same rules into a UserPromptSubmit hook, so they are re-attached as additionalContext on every prompt. Violations short-circuit the task instead of leaking through.

It is opinionated: 13 rules, English summaries with Japanese author-original quotes preserved verbatim per R16. Fork it, edit critical-rules.md, and reinstall — the wiring is the value, the rules are an example.

Status: Personal config dump, MIT-licensed for forking. The author uses this for their own workflow; no SLA, support guarantee, or roadmap. Issues and PRs are welcome but may be answered slowly or not at all. The bundled critical-rules.md is an example — replace with your own rules before relying on it.

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Install

Option A — Plugin (recommended, Claude Code v2.x+)

Inside Claude Code:

/plugin marketplace add hinanohart/claude-rules-injector
/plugin install claude-rules-injector@claude-rules-injector
/reload-plugins

The plugin bundles critical-rules.md, the hook, and the r-check skill (namespaced as /claude-rules-injector:r-check). Updates flow via the marketplace; no manual settings.json edits.

Option B — Manual install (legacy / for older Claude Code)

git clone https://github.com/hinanohart/claude-rules-injector.git
cd claude-rules-injector
bash install.sh

The installer:

• copies critical-rules.md to ~/.claude/critical-rules.md
• installs the hook at ~/.claude/hooks/inject-rules.sh
• installs the r-check skill at ~/.claude/skills/r-check/
• registers the hook in ~/.claude/settings.json (idempotent; creates .bak.<epoch>-<pid> backup before any edit)

Restart Claude Code after install. To confirm it works, send any prompt — the rules are re-attached as additionalContext on every turn.

Previously named claude-guardrails. Old URLs redirect; clone URLs still work via GitHub's auto-redirect.

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How it works

Path resolution order for the rules file:

1. CLAUDE_RULES_PATH env var
2. First line of ~/.claude/critical-rules.path
3. Default: ~/.claude/critical-rules.md

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Disable / customize

Goal	How
Temporarily disable injection	export CLAUDE_RULES_DISABLE=1
Use your own rules file	export CLAUDE_RULES_PATH=/path/to/rules.md
Pin a path persistently	echo /path/to/rules.md > ~/.claude/critical-rules.path
Look up one rule	invoke the r-check skill or run ~/.claude/skills/r-check/check.sh R11

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Uninstall

Plugin install:

/plugin uninstall claude-rules-injector@claude-rules-injector

Manual install:

bash install.sh --uninstall

The manual uninstaller writes a fresh settings.json.bak.<epoch>-<pid>, then edits settings.json in place to remove only the claude-rules-injector hook entry (sibling hooks are preserved). It removes the hook script and the skill. If $HOME/.claude/critical-rules.md was modified after install, it is preserved as critical-rules.md.bak.<epoch>-<pid> instead of being deleted.

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What's in the rules

13 rules across three priority tiers. Lines prefixed with 🔥 reproduce the original Japanese wording verbatim and should not be reworded (see R16); each is followed by an English paraphrase and an operational line.

Tier	Rules	What they cover
1 (immediate stop)	R11, R13, R15	Secret handling, security isolation, cross-session contamination
1.5 (special protocol)	R14, R16, R17	Pre-large-work possibility-exploration, 100% intent comprehension, write-target audit
2 (auto-progress)	R1, R2, R5, R7, R8, R12, R18	Response style, code quality, evidence, auto-progress, failure museum, agent-bash, web-search reality-check

The numbering has intentional gaps (R0/R3/R4/R6/R9/R10 are omitted) because some rules are locale- or person-specific and shouldn't be redistributed as defaults. Gaps are preserved so downstream tooling that addresses rules by ID stays stable across forks.

See critical-rules.md for the full text.

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Non-goals