Chapter 3 · logical ownership

System responsibilities

Logical components own clear inputs, outputs, and ends-here lines. An MVP may combine deployables; credentials still stay on the collector.

Figure 5. Logical components and responsibility boundaries

**Takeaway:** Telemetry does not pass through enrollment. Storage feeds queries, evaluation, Assurance, and notification. Scrape reads current gauges only.

Related: Interface catalog · Contracts

Component cards

UPS / protocol adapters

Accepted behavior · Proposed packaging

Owns: USB-HID / NUT / SNMP read paths; normalized readings; source identity fields
Runs: Inside the host collector process (ESP32: constrained USB-HID firmware path)
In / out: Hardware protocol in → structured observations out
Ends: Does not store fleet history, evaluate incidents, or write UPS controls

Host collector and constrained probe

Accepted

Owns: Sampling cadence, heartbeat, local buffer, upload attempts, role application, source tests
Runs: macOS / Windows / Linux / Pi host agent, or ESP32 firmware
In / out: Adapter readings + connectivity checks in → buffered telemetry + heartbeats out
Deps: Local secret store; platform service manager
Ends: Does not own fleet UI policy; does not accept dashboard-delivered secrets

Local persistence and upload

Owns: On-disk/flash queue, retention pressure signals, retry/backoff, ack cursor
Ends: When batches are acknowledged or explicitly dropped under overflow policy

Host disk caps and ~30-day targets are Proposed. ESP32 flash figures remain illustrative.

Enrollment, identity, configuration

Owns: Enrollment codes, collector credentials, site assignment, desired config records
Split: Dashboard-managed keys vs local secrets vs local host settings vs capabilities (not settings)

Telemetry ingestion

Accept batches, authenticate the collector, advance the acknowledgement cursor, and deduplicate. Proposed wire protocol.

Current-state & history queries

Latest + observation-timed history with gaps. Storage engine Open.

Incident evaluation & notify

Rules, grace, declare, deliver. Channels Proposed.

Battery Assurance

Evidence, installations, findings — monitoring-only. Accepted product rules.

Web dashboard & CLI

Operator surfaces. CLI grammar Proposed as shipped binary.

External monitoring

Prometheus scrape path Proposed. Does not replace durable replay.

MVP combine vs boundary. Ingestion + query + incident evaluation may ship as one service early. Keep ownership documents and interfaces distinct so storage, auth, and notify can split later. Never move UPS/SNMP secrets off the collector into the dashboard.