Track Production Burn Rate Acceleration

v20260707

cost-burn

Monitors the acceleration trend of production spending (burn rate) over defined time windows. It compares the latest spending bucket against the historical average, providing an early warning system. This is crucial for detecting sudden, unexpected cost spikes, such as a 'hot loop,' independent of overall budget limits.

Cost Tracking BurnRate Acceleration Observability Monitoring Production Alerting

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Overview

Burn-rate trend observability. The fourth leg of the cost-tracker forward-cost stack:

Question	Skill
"Have we crossed a threshold?" (reactive)	`cost-budget-check`
"When will we cross a threshold?" (predictive)	`cost-projection`
"Could we have spent less?" (comparative)	`cost-counterfactual`
"Is daily burn ACCELERATING?" (trend)	`cost-burn` ← this

Algorithm

Implementation: scripts/burn.mjs.

Read all session-* records from cost-tracking namespace.
Bin into --bucket duration windows (default 1d) over --lookback (default 14d).
For each bucket: {n: sessions, spendUsd: sum(total_cost_usd)}.
Compute delta = latest.spendUsd - mean(prior non-empty buckets).
If --alert-on-acceleration-pct N is set: exit 1 when deltaPct > N.

Smoke transcript (5 days @ $0.10/day, today $0.50 — 400% acceleration)

| Latest bucket spend | $0.500000 (1 sessions) |
| Prior bucket mean | $0.100000 (4 non-empty buckets) |
| **Delta (latest vs prior mean)** | **+$0.400000 (400.00%)** |

# | Window                              | Sessions | Spend
0 | 2026-06-15 14:16 → 2026-06-16 14:16 | 1        | $0.500000
1 | 2026-06-14 14:16 → 2026-06-15 14:16 | 0        | $0.000000
2 | 2026-06-13 14:16 → 2026-06-14 14:16 | 1        | $0.100000
3 | 2026-06-12 14:16 → 2026-06-13 14:16 | 1        | $0.100000
...

Drift alert exit code

$ cost burn --bucket 1d --lookback 7d --alert-on-acceleration-pct 50 ⚠ ALERT: latest bucket $0.500000 is 400.0% above prior mean $0.100000 (threshold +50%) exit 1

$ cost burn --bucket 1d --lookback 7d --alert-on-acceleration-pct 500 ✓ latest bucket within +500% of prior mean (actual delta: 400.0%) — OK exit 0

CI integration

# Fail the build if today's spend accelerated > 100% over the weekly mean
cost burn --bucket 1d --lookback 7d --alert-on-acceleration-pct 100 || alert-oncall

The alert is independent of budget — it triggers on rate ACCELERATION even when total spend is well under budget. Catches "we shipped a hot loop that burns 10× normal" before the budget alarm goes off.

Distinct from `cost-trend`

Skill	Data source	Question
`cost-trend`	`docs/benchmarks/runs/*.json`	"Is the benchmark drifting (win rate, latency)?"
`cost-burn`	`cost-tracking` namespace	"Is production spend accelerating?"

Both useful; they answer different questions on different data.

Edge cases

Sparse history (no prior non-empty buckets): alert is SKIPPED with a reason string, exit 0. Operators don't get spurious alerts on cold-start.
Prior buckets all $0 but latest > $0: delta is Infinity/null in JSON, marked new in the table. No alert fires (no baseline to compare against).
--bucket > --lookback: hard error, exit 2.

Info

Category Engineering

Name cost-burn

Version v20260707

Size 3.24KB

Source ruvnet/ruflo

Updated At 2026-07-09