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Design
oto — System Design ProposalDomain Research: Prometheus Alertmanager + Slackoto — Red-Team Memooto — SCOPE BOUNDARY (the doctrine)oto — BINDING SPECIFICATION v1
ADRs
0001 — PostgreSQL is the sole datastore; River is the job queue0002 — `internal/<domain>/{api,service,repository,domain}` with three model sets0003 — Alert, AlertOccurrence and AlertEvent are three distinct entities0004 — oto owns alert identity; Alertmanager's fingerprint is recomputed, not trusted0005 — A durable group key, and the AlertGroup generation owns the Slack thread0006 — The Alertmanager API v2 reconciler is mandatory, not optional0007 — Webhook response contract: 202 or 503. Never 4xx, never 429.0008 — Slack: `chat.update` in place is primary; threads are secondary; one colour attachment0009 — Rule definitions are snapshotted and versioned at fire time0010 — Server-Sent Events with durable resume, not WebSocket0011 — Validation is seven layers with two opposite trust models0012 — Pastel product chrome, saturated colour reserved exclusively for state0013 — oto is alert-first: the Flight Recorder Test defines the scope boundary0014 — Postgres is the only store; no TSDB or column store in v10015 — No stream processor; River in Postgres is the pipeline0016 — Cluster context arrives via MCP, on demand; never the Kubernetes event firehose0017 — Alertmanager-style matchers, not CEL; and a filter AST that keeps the door open0018 — Slack distribution: a customer-built internal app, credentials in config0019 — MIT licence0020 — Broadcast the transitions that must be seen0021 — Correctness and testing strategy0022 — Length-prefixed identity pre-images0023 — Terminal thread states are decided first, and the send is three phases0024 — Retention defaults, what each boundary destroys, and cold storage0025 — The alert list resolves rule snapshots in a batch, not per row0026 — `refire_grace` and the flap thresholds, derived from a real rule corpus0027 — Delivery drills: a synthetic alert through the real pipeline, and the mark that keeps it out of the numbers0028 — Non-urgency motion: one-shot events, honest activity loops, and nothing else0029 — Type and radius scales, read off the product rather than drawn for it0030 — Tier A repainted as Washi & Ink / Konshi Sutra; accent moves to beni0031 — Sharp corners and higher-contrast grid lines within Washi & Ink; colours unchanged0032 — Dark-theme accent moves from beni to plum-blossom blue-and-white; light untouched0033 — The alert filters are a toolbar above the table, not a panel in the rail0034 — Notifications is a destination, and the record it keeps is readable0035 — Decorative ink as a masked wash: one primitive, four motifs, and the placements it is refused0036 — AlertOccurrence becomes AlertCase, and `case` is argued against FR-1 by name0037 — A Wording is Liquid, and the structure around it stays oto's0038 — The group key is derived from the alert's own labels0039 — Group close stays activity-driven0040 — A Case is `open` or `closed`, and it is never reopened0041 — The Alert/Case allocation, and the one rule that decides it0042 — Storm damping is removed, because the defence was built before its object0043 — The Slack action row renders five elements, and the fifth is the snooze pair0044 — A count condition is a silence the operator asked for, and `below_threshold` is how oto says so0045 — A Case is a conversation, and one Slack thread per alert is the accepted cost0046 — Corners round again: ADR 0031's radius override is reversed0047 — A channel answers to a connection, and Slack gets two scopes back0048 — A Wording is spelled by its channel, and the marks in between are oto's0049 — A Wording is selected by its own clause, not by a route0050 — A NotificationTemplate is one whole message, and its policy says which one0051 — A `raw` template owns the whole message, and a template may carry its replies0052 — An Incident is drawn over Cases, and its response is handed off0053 — An Investigator reads, proposes, and never decides delivery0054 — A Remedy earns the write path0055 — An incident-tool integration is data or a bridge, never code inside oto0056 — A Case the upstream stopped speaking about expires, and says why
Setup
Configuration referenceReaching an incident tool: the envelope, a mapping, or a bridgeInvestigatorsRemediesConnecting oto to SlackThe live Slack verification runTuning otoConnecting oto to VictoriaMetrics (vmalert)The generic webhook and `oto.notification.v1`
Runbooks
oto runbooksAlert search — optional partial/substring matching on alert namesoto_clock_skew_secondsoto_delivery_claim_lost_totaloto_ingest_accepted_totaloto_ingest_alerts_totaloto_ingest_duplicate_totaloto_ingest_duration_secondsoto_ingest_fingerprint_mismatch_totaloto_ingest_process_duration_secondsoto_ingest_rejected_totaloto_ingest_shed_totaloto_job_duration_secondsoto_job_queue_depthoto_jobs_dead_totaloto_jobs_enqueued_totaloto_jobs_failed_totaloto_jobs_panics_totaloto_jobs_snoozed_totaloto_jobs_started_totaloto_jobs_succeeded_totaloto_jobs_unknown_version_totaloto_render_invalid_totaloto_slack_unknown_action_totaloto_stream_connectionsoto_stream_events_coalesced_totaloto_stream_events_dropped_totaloto_stream_events_fetched_totaloto_stream_events_published_totaloto_stream_fetch_errors_totaloto_stream_listener_reconnects_totaloto_stream_notify_malformed_totaloto_stream_notify_received_totaloto_stream_poll_recovered_totaloto_stream_resync_totaloto_thread_gap_recovered_totaloto_thread_head_wait_secondsoto_thread_order_decisions_total

oto_jobs_dead_total
Type counter
Labels kind, queue, class
Registered in internal/platform/jobs/metrics.go; incremented in internal/platform/jobs/worker.go
Alertable YES — page on it. The help string says ALERT ON THIS
Rule OtoJobsDead in deploy/prometheus/oto-rules.yaml

What it counts

Section titled “What it counts”

Jobs that will never run again. There are three ways in, and they are distinguishable:

How class dead_reason in the log
A terminal error class — permanent, config_invalid, auth_expired — which never retries that class terminal_error
The retry budget was spent (13 attempts retryable, 21 rate-limited) retryable / rate_limited attempts_exhausted
The payload version is newer than this binary permanent unknown_payload_version — also on oto_jobs_unknown_version_total

Why every increment matters

Section titled “Why every increment matters”

Together with unknown_version, this is the metric that means work was accepted and then silently not done. Depending on kind, one increment is: an ingested batch that never became alerts, an alert that never became a notification, or a notification that never reached a human. oto’s silence must never be indistinguishable from “no alert” — this counter is what makes the difference visible.

What to check

Section titled “What to check”
  1. The dead-letter log record. The default sink logs one ERROR per dead job with the full payload — deliberately, because it is the last copy: 
    msg="jobs: job is dead, it will never run again"
    job_id= job_kind= queue= attempt= attempts= error_class= dead_reason= payload= error=
    Search for dead_reason to split the three cases above.
  2. river_job for that kind, in discarded / cancelled state.
  3. If kind="deliver.dispatch": notification_deliveries for the row, and GET /api/v1/deliveries/{id} for the classified error. Also check the channel’s health — a config_invalid or auth_expired death sets it, with a UI banner.
  4. If kind="ingest.process_batch": the batch is still in ingest_batches; it was accepted and is now unprocessed.

What to do, by class

Section titled “What to do, by class”
  • auth_expired — the credential was revoked. This is the case the class exists to separate from “Slack is flaky”: re-authorise the workspace (docs/setup/slack.md) and the banner clears.
  • config_invalid — oto built something the provider refused. If the message is a render/block problem it is an oto bug: file it with the delivery id (docs/setup/slack.md §errors). Otherwise fix the channel configuration.
  • permanent — read the error. A channel that no longer exists, a conversation oto was removed from, a payload the provider will never accept.
  • retryable / rate_limited exhausted — the dependency was down for longer than the budget. Fix the dependency first, then decide whether to replay: the payload in the log is complete, and re-enqueuing is safe for every idempotent kind (ingest is ON CONFLICT; delivery is guarded by the §G.5 claim).
  • Do not raise MaxAttempts as a first response. Twelve retries already spans minutes; if that is not enough the dependency is not flaky, it is down.