Manage project-level agent behavioural rules recorded in a single rules file. Use when the user says 'new rule', 'add a rule', 'record that', 'make a rule that', 'note this', 'take note of', 'new instruction', or asks to codify an agent directive. Read the rules file to check existing rules before adding a new one. DO NOT use for ephemeral notes, one-off instructions, or instructions that belong in the project's own agent-facing docs. Triggers: 'new rule', 'add a rule', 'record that', 'make a rule', 'codify this', 'rule about', 'create a directive', 'note this', 'take note of', 'new instruction'.