audit-infra-cost — Hosting spend without hurting reliability

Degree of freedom: HIGH — quantify and plan. Phase 2 stays plan-only until approved. Never propose a cut that weakens backups (plan-backup-dr).

Read-only. Find where money leaks in the infra bill and plan cuts that do not trade away reliability.

For a solo operator, infra cost is runway. A silent egress or storage leak can double a bill nobody is watching.

Quantify and plan. Apply only on approval. Never propose a cut that weakens backups (plan-backup-dr) or user experience.

This skill vs neighbors

How to reason

1. Observe — billed resource, pricing model, and (if exposed) the breakdown line
2. Interpret — is this utilization, a leak (egress/storage/zombies), or a tier mismatch?
3. Classify — safe quick win / medium / structural / do-not-cut (backup/UX)
4. Severity — by $ magnitude × reliability risk, not by how easy the cut looks

Worked example

Observe: object-storage bill is 40% of spend; logs prefix has no lifecycle; backups retained 90 days (DR requirement). Interpret: unbounded logs are the leak; backup retention is not a cut. Classify: safe quick win (expire temp logs) + do-not-cut (backups). Severity: major $; reliability risk low if only temp logs expire. Finding: logs | ~X% | lifecycle 7d | do not touch backup prefix

Phase 0 — Map the spend surface [HIGH freedom]

Enumerate billed resources and, if the provider exposes it, the breakdown:

• Compute (functions / servers / containers)
• Database (compute + storage + connections)
• Object storage (GB + operations)
• Egress (usually the sneaky line)
• CDN, per-seat / per-project fees

Note each pricing model (per-request, per-GB, per-hour, tiered) — that is where the leak hides. Pricing tiers change: fetch the provider's current pricing page rather than quoting tiers from memory; a remembered price is not evidence for a saving estimate.

Phase 1 — Waste [HIGH freedom]

Egress — Large assets from origin every request? Unoptimized images? Hotlinking / unthrottled public endpoints? Cross-check audit-bundle-size.

Storage growth — Unbounded uploads, logs, backups that never expire, orphans after DB deletes. Lifecycle to cheaper tiers?

Over-provisioning — Sized for a rare peak, 24/7 low utilization. Pair with test-load. Under-provision that forces expensive workarounds is also a finding.

Serverless — Keep-warm waste, chatty N+1 invocations, long functions that belong on a queue, cron too frequent.

Database — Full scans, missing indexes (backend-db-performance), pool misconfig forcing a bigger instance, unbounded rows with no archive.

Zombies — Duplicate staging, unused region, leftover add-ons.

Tier fit — Next tier cheaper than overages? Paid add-on cheaper than the current pattern?

Phase 2 — Plan (approve before executing) [HIGH freedom — plan only]

Estimate saving magnitude ("egress is ~X% of the bill; CDN cuts most of it") and reliability risk.

• Safe quick wins — CDN/cache, image optimize, expire temp logs, delete zombies, add the missing index
• Medium — right-size to measured load, lifecycle-tier cold data, batch chatty calls, queue long work
• Structural — plan/tier change, architecture shift

Protect plan-backup-dr items. Do not expire backups to save cents.

Definition of Done

• Billed resources + pricing model enumerated
• Egress / storage / compute / serverless / zombies / tier-fit scored
• Right-size vs real utilization or test-load
• Each finding has saving magnitude + reliability risk
• Nothing proposed that weakens backups or UX
• Plan approved before change

Self-critique before reporting [LOW freedom — do not skip]

1. Quantified — each finding has a saving magnitude, even if rough
2. Backups protected — no expire-backups-to-save-cents item
3. Right-sized to evidence — test-load or utilization, not a guess
4. Right owner — CI minutes → audit-cicd; tokens → plan-llm-cost-guardrails
5. Nothing applied until approved

Output format

1. Spend surface — resource | model | rough share
2. Findings — leak | est. saving | fix | risk
3. Fix plan — safe-quick-win → structural
4. Read-only until approved

Related

• audit-cicd — pipeline cost
• plan-llm-cost-guardrails — token spend
• test-load — capacity numbers
• plan-backup-dr — do not cut restore
• audit-bundle-size / backend-db-performance — technical levers