feat(coretime-alert): optional discord mention and --fake-alert drill

[mrq1911]

why

Alerts currently post an embed with no top-level content. Discord does not send a notification for mentions inside an embed — only message content does. So today a coretime renewal alert lands silently in the channel and is only seen by whoever happens to scroll past it. The renewal right is genuinely lost at the region deadline, so a silent alert is close to no alert.

There was also no way to see what a real alert looks like without waiting for an actual deadline — --test only proves the webhook is reachable.

what

• ALERT_MENTION (new, optional env var) — posted as top-level content above the embed, so alerts actually ping. Takes @here, <@&ROLE_ID> or <@USER_ID>. Sets allowed_mentions explicitly rather than relying on the webhook default, so a role not flagged "mentionable" still pings. Unset, the payload is byte-identical to today's.
• --fake-alert (new flag) — posts one synthetic alert per configured chain (Hydration URGENT, Basilisk WARNING) through the real buildEmbed path. Each is titled 🧪 [DRILL] with a "this is a test alert" line and a synthetic drill footer so it can't be mistaken for a live deadline. Contacts no RPC and does not touch the state file, so it cannot disturb the cooldown of a real standing alert.
• README: config-table row, the embed-doesn't-ping gotcha, ID formats, drill docs.
• lark-stack.yml: ALERT_MENTION wired up.

Both chains were already watched — Hydration (task 2034, Polkadot) and Basilisk (task 2090, Kusama); no change to coverage.

testing

Dry-run verified with and without the var — unset produces exactly the current payload; set produces:

"content": "<@...>",
"allowed_mentions": { "parse": ["everyone","roles","users"] }

Not yet run against the live webhook — that happens at deploy.

deploy notes

Needs an image rebuild; autoredeploy on the lark coretime-alert stack picks up :latest, and ALERT_MENTION must be set on the service.

Unrelated, but worth flagging: DISCORD_WEBHOOK_URL is stored in plaintext in the stack env, so it surfaces in any Swarmpit service dump. The script already supports DISCORD_WEBHOOK_URL_FILE if we want to move it to a Swarm secret.

[github-actions]

Runtime version has not been increased.

[Copilot]

🟡 Changes recommended

Two moderate issues and one documentation nit remain unresolved.

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Pull request overview

Adds optional Discord mentions and a synthetic --fake-alert drill to the coretime renewal watchdog.

Changes:

• Adds top-level mention payloads with explicit mention permissions.
• Adds synthetic alerts without RPC access or state changes.
• Documents configuration and wires ALERT_MENTION into the stack.

File summaries

File	Summary
scripts/coretime-alert/README.md	Documents configuration and drill behavior; cooldown wording needs to distinguish test modes (nit, 3 votes).
scripts/coretime-alert/lark-stack.yml	Wires ALERT_MENTION into the deployment stack.
scripts/coretime-alert/check.mjs	Implements mentions and fake alerts; moderate issues remain with dry-run compatibility and configurable fake-alert shortfalls (1 vote each).

Review details

Suppressed comments (2)

scripts/coretime-alert/check.mjs:231

• With ALERT_MENTION unset, this changes the --dry-run output from the previous { embeds } shape to { username, embeds }. That contradicts the stated byte-identical compatibility claim and the dry-run verification; either preserve the old diagnostic shape when unset or update the claim to distinguish the HTTP payload from the dry-run output.

    console.log(JSON.stringify(payload, null, 2));

scripts/coretime-alert/check.mjs:300

• This fixture assumes the configured target is exactly three: it hard-codes one secured core and two pending renewals but derives shortfall from desiredCores - 1. With a valid override such as HYDRATION_DESIRED_CORES=1 or 4, the drill displays a zero/incorrect shortfall while still emitting an alert. Derive the synthetic core lists and shortfall from the configured target, or make the fixture explicitly independent of that setting.

      shortfall: chain.desiredCores - 1,

• Files reviewed: 3/3 changed files
• Comments generated: 1
• Review effort level: Lite

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[mrq1911]

drilled and deployed. --fake-alert posted both DRILL embeds through the live webhook with top-level content set, and the ping landed — so the mention path works end to end. lark now runs sha256:31e5f36e with ALERT_MENTION on the stack, re-confirmed from inside the running container.

basilisk was sitting at URGENT when I started (0/3 secured, 5.5d to region begin) and got renewed mid-deploy, so both chains are 3/3 now and no real alert is pending.

[github-actions]

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