Observances — a historical day, posted as it happened

A server owner can turn on a timeline: the events of a historical day, posted one at a time as their minutes come round on the anniversary. 8:46 AM arrives at 8:46 AM.

One timeline ships: September 11, 2001.

Admin → your server → Observances (/admin/<serverId>/observances).

Why it works this way

A block of text nobody reads to the end is the normal way a bot marks a date. Spreading the same record across the day it describes is the point of this feature — the pace is the content.

Off for every guild, always, until somebody turns it on. There is no enable-for-all switch and there is no default channel. A commemoration belongs to the server that holds it; a platform scheduling one on its members' behalf is a different and much worse product.

Settings

The timezone is a real choice, not a formality. The default is the zone the events happened in, so the times mean what they mean in the record. A server whose members are all in Sydney may prefer the day to land on their own clocks instead. Both readings are defensible; neither is assumed.

The grace window is what stops a burst. The dispatcher ticks once a minute, and ticks get missed — a deploy, a queue backlog, an incident upstream. Without a bound, an outage from 9 AM to noon would empty three hours of a memorial into the channel at once, in the wrong order relative to the day. Past the window an event is recorded as skipped instead. A gap is quiet. A dump is not.

What a post contains

Each post is one event, and it is meant to be legible to somebody who scrolled into the channel without context:

• The time and the title — 8:46 AM — The North Tower is struck.
• The body, written to stand alone. These arrive hours apart.
• A map link to where it happened, where there is a single place. The link is the documented Google Maps URL API, built from either a coordinate or a place name — a named search that lands on the right building beats a coordinate invented to three decimals.
• A photograph, where a properly-licensed one of that moment exists.
• A footer naming the day, on every post rather than only the first, plus the photo credit.
• Further reading — Wikipedia, the 9/11 Commission Report, the National Park Service, the memorial — and the photograph's own Commons file page, because the licences want a link to the source and an embed footer cannot carry one.

Events with no single place get no pin — an aircraft in the air, an order that applied to the whole country. Events with no properly-licensed photograph get no image. An empty frame is better than a stock photograph standing in for a death, and a pin invented for a location nobody can verify is worse than none.

No live flight trackers. Flightradar24 is the obvious thing to reach for and it does not work: its history does not reach back to 2001, and all four flight numbers were retired after the attacks, so flightradar24.com/data/flights/aa11 answers "There is currently no data available for your request." A link that resolves to an empty page is worse than no link, and worse still on this day.

Parentheses must be encoded in a link URL. Discord ends a [label](url) at the first ) it meets, so World_Trade_Center_(1973–2001) renders as a broken link trailing the stray text 1973–2001). mdLink() percent-encodes them; do not hand-build a masked link without it.

Where the photographs come from

Every image is a public-domain or Creative-Commons file on Wikimedia Commons — FEMA, the Navy, the Air Force, the National Park Service, Customs and Border Protection, White House photographers, and a few CC-licensed contributions. Attribution rides in the embed footer because those licences require it.

Check what a file actually shows, not what its filename suggests. Read the Commons description and the date before you use one. Four of the first set picked here were wrong: a dust cloud captioned WTC2 sat under the North Tower's collapse, and two FEMA photographs taken on 14 and 16 September — one of them the President meeting rescue teams — sat under events from the morning of the 11th. A caption is evidence. A filename is not.

The famous press photographs of that morning are not used. Almost all of them are still under copyright to AP, Reuters and Getty, and a memorial is a bad place to be casual about somebody else's work. If you add a timeline, hold its images to the same line.

In plain-text mode there is no embed frame, so the map and the photograph are spelled out as URLs wrapped in <>. Discord renders a masked [text](url) link inside an embed only — in ordinary message content it posts the brackets literally — and the angle brackets are what suppress the auto-preview a guild turned embeds off to avoid.

How it runs

Exactly like the other minute-cadence jobs:

orchestrator-worker cron (* * * * *)
  → POST /api/superadmin/workflows/dispatch
    → preset `minute-anniversary-timeline`
      → operation `postAnniversaryTimelines`
        → processAnniversaryTimelines(db, botToken)   [src/lib/db/anniversary-timeline.ts]

The preset is auto-seeded by slug on the dispatch tick, so a deploy is all the setup there is. It is also exposed as the manual job post_anniversary_timelines under Admin → Superadmin → Cron.

On 364 days a year a tick costs one indexed read of enabled rows and a date comparison.

Posting exactly once

The unique index (timeline_id, year, event_key) on anniversary_timeline_posts is the lock, not a report. Each event is claimed with INSERT OR IGNORE and only posted if the insert actually changed a row — so when two ticks overlap, or a Workflow step retries, SQLite decides the winner rather than timing does.

A send that fails is marked failed and is not retried. On this of all days, a duplicate is worse than a gap: the failure usually means the bot cannot post in that channel, and retrying every minute would either do nothing or, worse, succeed twice.

A row stuck at claimed means the process died between claiming and posting. It is left alone for the same reason.

Content

src/lib/anniversaries.ts. Deliberately in code, not in the database:

• Every guild gets the same record. A per-server editable copy is a way for one to quietly drift wrong with nobody to notice.
• Changing what happened should be a commit with a diff and a reviewer.

Event keys are permanent — they are the idempotency key. Renaming one re-posts an event that already went out.

The September 11 timeline follows the 9/11 Commission Report where a commonly quoted time and the Commission's differ. Times are the seismically- and radar-confirmed ones, truncated to the minute. The register is plain declaratives: it is read by people who remember the day and by people born after it, and the second group is now most of them.

Adding a timeline

1. Add an AnniversaryTimeline to ANNIVERSARY_TIMELINES in src/lib/anniversaries.ts: a key, month/day, sourceYear, the zone it is recorded in, and events in time order with exactly one opening and one closing.
2. Nothing else. The schema already carries timeline_key, the dashboard reads the registry, and the tests assert ordering, unique keys and the opening/closing invariant across every registered timeline.

Sourcing is the work, not the plumbing. A timeline that is nearly right is worse than no timeline, because it will be read as authoritative and nobody checks.