/edikt:invariant

Capture a hard architectural constraint that must never be violated.

Usage

/edikt:invariant no floats for money
/edikt:invariant                         ← extracts from current conversation

What is an invariant?

An invariant is not a guideline — it's a rule where violation causes real harm: data corruption, security breaches, double-charges, domain boundary violations. Invariants are non-negotiables.

Good invariants:

• "All monetary amounts stored as integer cents. Never use float64 for money."
• "Domain package imports only stdlib. No HTTP, no SQL, no framework types."
• "All payment operations require an idempotency key."

Not invariants (use .claude/rules/ instead): preferences, "try to" statements, style guidelines, things that are just good practice.

Two modes

With argument — define from scratch

/edikt:invariant no floats for money

edikt creates the invariant with precise language: what the rule is, why it exists, and what violation looks like.

Creates: docs/invariants/INV-{NNN}-no-floats-for-money.md

No argument — extract from conversation

/edikt:invariant

Extracts the last hard constraint discussed in the current conversation.

Proactive suggestions

The Stop hook watches every Claude response for hard constraint signals. When it detects one, Claude suggests:

💡 This is an invariant — run `/edikt:invariant` to capture it.

Output

docs/invariants/
└── INV-001-no-floats-for-money.md

Invariants are loaded by /edikt:context at all depth levels — they're always in Claude's context because they're always non-negotiable.

Natural language triggers

• "that's a hard rule"
• "never do X"
• "add an invariant"
• "that must never be violated"