CAS-2540 — Cargo-targets disk budget

Status: shipped (2026-05-13, commit 7d57df0)
Owner: Castellan (implementation), Master of Craft (architecture)

Problem

Recurring disk-full incidents blocked all engineering work. The Worktree Sweeper and Ravens disk probes caught the symptom but only after the crisis, and only through manual intervention. Each fill required a human-triggered migrate-worktree-cargo.sh run to recover.

What shipped

Five-layer structural fix:

Layer	Component	What it does
1	`enforce-cargo-budget.sh`	LRU eviction across all officer target dirs — evicts `deps → build → incremental` until under budget. Skips files younger than 5 min and respects the smoke-test lock.
2	`cargo-budgets.conf`	Per-officer budget caps: backend/frontend 12 GB, others 6–8 GB. Config-driven — no code change needed to adjust.
3	`com.paperclip.cargo-budget-enforcer.plist.tmpl`	launchd daemon: hourly enforcement (`StartInterval=3600`) + `RunAtLoad=true`. Replaces the 4-hour Paperclip routine (which ran only while Paperclip was up).
4	`cargo-budget-alert.sh`	Per-role 80% threshold alert. Fires after each enforcement run; surfaced to Paperclip logs.
5	`enforce-cargo-budgets.sh`	Dispatcher wrapper wired into `install.sh` and `check-daemon-health.sh`.

Key behaviours

Smoke-lock guard — eviction is skipped when ~/.paperclip/state/smoke-test.lock is held by a live process. Prevents pruning incremental artifacts mid-smoke.
5-minute safety window (MIN_AGE_MINUTES=5) — recently written files are never evicted. Protects in-flight builds.
Dry-run mode — enforce-cargo-budget.sh --dry-run reports what would be evicted without touching disk.
Idempotent — safe to run multiple times; already-under-budget dirs are no-ops.

Files

.agents/skills/casaconomy-task-worktree/scripts/
  enforce-cargo-budget.sh        — main enforcer
  cargo-budgets.conf             — per-officer GB caps
.paperclip/
  scripts/enforce-cargo-budgets.sh   — dispatcher
  scripts/cargo-budget-alert.sh      — 80% alert
  scripts/check-daemon-health.sh     — wired in for health reporting
  launchd/com.paperclip.cargo-budget-enforcer.plist.tmpl  — daemon template
  install.sh                         — registers daemon on setup

Follow-up (separate CAS)

Disk-level push notification
Post-merge hook integration
disk-budget-status.sh summary command
SKILL.md entry for task-worktree skill