nix-store-cleanup-guard

name	nix-store-cleanup-guard
description	Perform or update Nix store cleanup workflows with explicit safety checks and retention strategy. Use when reclaiming disk from `/nix/store`, editing `scripts/cleanup.sh`, deciding between aggressive and conservative generation pruning, or preparing cleanup commands for macOS/Linux systems.

Nix Store Cleanup Guard

Overview

Run cleanup with clear risk signaling, predictable retention policy, and before/after measurements so space recovery does not silently remove required rollback points.

Workflow

1. Measure current usage and identify urgency.
2. Choose retention mode before deletion.
3. Execute cleanup commands in the correct profile scope.
4. Re-measure and report reclaimed space.
5. Document rollback impact explicitly.

Retention Modes

Mode	Behavior	When to choose
Conservative	Keep recent generations (for example +3) before GC	Normal maintenance where rollback matters
Aggressive	Delete old generations and run full GC (-d)	Disk pressure emergencies or explicit user request

Command Patterns

• Measure:
  • du -sh /nix/store
• System profile cleanup on macOS:
  • sudo nix-env --delete-generations old --profile /nix/var/nix/profiles/system
• Home Manager profile cleanup (if present):
  • nix-env --delete-generations old --profile ~/.local/state/nix/profiles/home-manager
• User profile cleanup:
  • nix-env --delete-generations old
• Garbage collection:
  • nix-collect-garbage -d

Guardrails

• Require explicit confirmation intent before aggressive pruning.
• Prefer conservative retention when no urgency is stated.
• Keep script behavior idempotent and transparent.
• Warn that deleting generations reduces rollback options.

Completion Checklist

1. Report before/after store size.
2. State chosen retention mode and rationale.
3. State rollback consequences for the chosen mode.
4. Update scripts/cleanup.sh and scripts/AGENTS.md together when workflow behavior changes.