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The Artifact

IaC plan diff + drift-detector live view.

Pick a plan, see the diff. Click a resource, see its current state vs. desired state. Drift alarms are receipts.

Pln
Dimension
Plan diff
4.10 J · OpenTofu 1.8
per call

HCL2 plan output, resource by resource.

The planfile is the contract. 14 additions, 0 changes, 0 destroys. Each resource carries a content-addressed module source (git+sha) so the same plan re-derives byte-identically on any host. Plan output is JSON-rendered for diffing and HCL-rendered for reading.

Sample receipt
JWP ReceiptPayload
kind "eng.iac.plan"
plan_hash blake3:88ee2c47…001a
added 14
joules 4.1
cite "OpenTofu 1.8 · HCL2"
sig "ed25519:0x4f...c1a"
Anatomy — operational specs
tofu_version
1.8.4
providers
pge ~> 0.7, utility-smartmeter ~> 1.2
App
Dimension
Apply audit
11.60 J · 6m12s
per call

Per-resource creation log with timing + provider response.

Every resource creation records (timestamp, provider, http_status, latency_ms). PG&E rate-limited at 4 rps; total apply ran 6m12s end-to-end. State file encrypted AES-256-GCM and uploaded with a lock_id that any concurrent apply would have to wait on.

Sample receipt
JWP ReceiptPayload
kind "eng.iac.apply"
duration_s 372
state_lock_id 9a4c-...-c0e2
joules 11.6
cite "OpenTofu 1.8"
sig "ed25519:0x4f...c1a"
Anatomy — operational specs
backend
s3 + dynamodb-lock
encryption
AES-256-GCM
Dft
Dimension
Drift detector
0.78 J / day · 15-min loop
per call

Background loop diffing live state against the desired state.

Re-runs `tofu plan -refresh-only` 96 times per day. Any non-zero drift surfaces as a receipt and a page. Median 30-day drift: 0. When drift is intentional (e.g., utility back-office changed a rate), it's adopted via `tofu apply -target=...` with a fresh plan-sign-apply cycle.

Sample receipt
JWP ReceiptPayload
kind "eng.drift.watch"
interval_min 15
drift_count_30d 0
joules 0.78
cite "OpenTofu 1.8 -refresh-only"
sig "ed25519:0x4f...c1a"
Anatomy — operational specs
checks_per_day
96
alarm_channel
pagerduty:eng-iac
MCP
Dimension
MCP audit
0.18 J · 2025-11 draft
per call

Every agentic tool call gated by a Cedar predicate.

An agent that wants to run `tofu/apply` calls the MCP server with a planfile URI. A Cedar 4.0 predicate (`sre-prod-low-cost.cedar`) checks principal role + estimated cost; only admitted calls reach OpenTofu. The audit_id is the join key between agent trace and IaC apply receipt.

Sample receipt
JWP ReceiptPayload
kind "eng.mcp.tool.admitted"
tool tofu/apply
decision admit
joules 0.18
cite "MCP 2025-11 §6.2 · Cedar 4.0"
sig "ed25519:0x4f...c1a"
Anatomy — operational specs
mcp_server
engineeringos-mcp 0.9.3
policy_repo
policies/engineeringos@af12c0
Tag
Dimension
FinOps tag
0.42 J · FOCUS 1.1
per call

Cost-center + joule-budget tags on every resource.

FOCUS 1.1 schema tags get applied at apply time: cost_center, service, joule_budget_per_day. Cloud-cost API rolls dollars; Insights rolls joules. When the joule_budget threshold is crossed, a receipt fires before the dollar bill is even due.

Sample receipt
JWP ReceiptPayload
kind "eng.finops.tagged"
tags cost_center, service, joule_budget_per_day
joule_budget_per_day 240
joules 0.42
cite "FinOps FOCUS 1.1"
sig "ed25519:0x4f...c1a"
Anatomy — operational specs
spec
FOCUS 1.1 (2024-12)
rollup
daily

EngineeringOS, in one line

build, made inspectable.

Click anything. The same primitives that compose the rest of the Transaction Science family — receipts, joules, signed transport — show up here too. The family is one system.