Communications Console
A fictional support watch at Camp Kestrel coordinating base services, transport, facilities, and supplies. Five channels share a chronological conversation view and a channel-specific composer. The channel rail shows messages that need your acknowledgement and where you have saved a draft.
Interactive product exampleOpen workspace ↗
Communications Console
Camp Kestrel support watch
Relay connected
Base support
Coordinate base services and the next watch handover.
2026-10-02 · All times UTC
- Lt Jordan HayesWatch supervisor
Morning support handover is open. Keep facilities, transport, and supply updates in this channel.
MSG-0410Delivered to channelNo acknowledgement requested - Sgt Alex MorganYou
The standby generator inspection is complete. Facilities, confirm the log is ready for the 10:00 handover.
MSG-0411Delivered to channelAwaiting acknowledgement - Facilities deskBase services
Please acknowledge the east service entrance reopening at 09:45, after the safety check. The inspection log is ready for handover.
MSG-0412Delivered to channelAcknowledgement requested
Fictional exerciseLocal messages only · No external service connected
Exercise controls
Change the local relay state or supply a recipient receipt. Restoring the connection does not submit a saved draft.
Work a channel
Choose a channel to read its messages. Selection moves keyboard focus into the conversation. Channel details contains the channel lead, participants, posting access, and source time. At narrow widths channels form a horizontal scroll rail above the conversation.
Write an update, optionally select Request acknowledgement, then use Send message. Enter inserts a new line. Each channel retains its draft and acknowledgement choice while you work elsewhere. A successful local submission clears only that channel's draft. Rejected or unconfirmed actions retain it, and pending feedback stays attached to its original channel.
Delivered to channel means the source reports delivery. Acknowledged by records a separate recipient action. Acknowledging an incoming request does not acknowledge your own outgoing messages. The notices channel is read-only for this operator, and Supply begins with an empty conversation.
Open Exercise controls to simulate connection loss, restore the connection, or supply a recipient acknowledgement for your latest eligible message in the selected channel. During connection loss the last snapshot remains visible, drafts remain editable, and sending and acknowledgements are disabled. Restoring the connection never submits a draft automatically. All exercise actions update this browser session; no external service receives messages.
Application ownership
const [selectedChannelId, setSelectedChannelId] = useState(initialSnapshot.channels[0]?.id ?? null);
<CommunicationsConsole
snapshot={snapshot}
selectedChannelId={selectedChannelId}
onSelectedChannelChange={setSelectedChannelId}
onAction={requestCommunicationsAction}
/>;requestCommunicationsAction is an application adapter. Bind each request to its originating source and reconcile responses before publishing a new snapshot. Requests in different channels may finish out of order; an older response must not replace newer history, and a response from a replaced source must not restore that source. Use the service's revision or event ordering for this decision.
The application supplies channel membership, posting permissions, operator identity, message history, delivery status, acknowledgement receipts, connection state, and source timestamps. onAction receives a send or acknowledge request and returns an accepted or rejected result with a user-facing message. An accepted callback does not manufacture a delivered message; the application publishes authoritative history through snapshot.
Each request carries a requestId. An unchanged retry after an unconfirmed response retains that identity. The application must reconcile uncertain outcomes and implement idempotent writes, authentication, delivery receipts, recipient acknowledgement policy, durable history, and reconnect synchronization. A payload without an unresolved attempt receives a new request identity. Returning to an unresolved payload retains its original identity, even after another message or acknowledgement. Keep identities stable when reconnecting; replace snapshot.id only when changing the complete workspace source, which discards drafts and pending feedback.
applyCommunicationsAction is an immutable local reference reducer. It checks connectivity, channel membership, posting access, message length, delivery state, and acknowledgement eligibility. It deduplicates accepted sends by request identity. The fixture advances a supplied exercise clock with each transition. Production services own the real clock and durable transport behavior.
import { CommunicationsConsoleDemo } from "./patterns/communications-console";
<CommunicationsConsoleDemo />View recipe source (7 files)
Copy all files into your app, preserving their relative paths.
Package imports: @operator-ds/react, react.
patterns/communications-console/index.ts
export { CommunicationsConsole } from "./communications-console";
export { CommunicationsConsoleDemo } from "./demo";
export { createCommunicationsSnapshot } from "./fixtures";
export { applyCommunicationsAction } from "./communications-state";
export type {
CommunicationsPerson,
CommunicationsChannel,
CommunicationsMessage,
CommunicationsSnapshot,
CommunicationsActionRequest,
CommunicationsActionResult,
CommunicationsConsoleProps,
} from "./types";
patterns/communications-console/communications-console.tsx
"use client";
import { Fragment, useId, useLayoutEffect, useRef, useState } from "react";
import { Badge, Button, Checkbox, EntityPreview, Field, Textarea } from "@operator-ds/react";
import { formatUtcInstant } from "../operational-domain";
import type {
CommunicationsActionRequest,
CommunicationsActionResult,
CommunicationsConsoleProps,
CommunicationsMessage,
} from "./types";
type Draft = { body: string; acknowledgementRequested: boolean };
const emptyDraft: Draft = { body: "", acknowledgementRequested: false };
const focus =
"outline-none focus-visible:outline focus-visible:outline-2 focus-visible:outline-oprt-border-focus";
/** "HH:MM" in UTC. Kept for callers of the earlier helper; the console itself shows zone and date. */
export function communicationsTime(at: number) {
return new Date(at).toISOString().slice(11, 16);
}
const isoOf = (at: number) => new Date(at).toISOString();
const dayOf = (at: number) => isoOf(at).slice(0, 10);
/** "HH:MM:SS UTC" for a message, "HH:MM UTC" where the room is tight. */
const clock = (at: number, seconds: boolean) => `${isoOf(at).slice(11, seconds ? 19 : 16)} UTC`;
/** "YYYY-MM-DD HH:MM:SS UTC". Whole seconds: the console does not show sub-second timing. */
const stamp = (at: number) => formatUtcInstant(isoOf(at), { milliseconds: "never" });
/** One line of room for the end of a list, in pixels: closer than this counts as at the end. */
const END_SLACK = 24;
/** A time with its date and zone; a narrow column breaks between the date and the time, never inside either. */
function Stamp({ at, className }: { at: number; className?: string }) {
const text = stamp(at);
return (
<time dateTime={isoOf(at)} {...(className ? { className } : {})}>
<span className="inline-block">{text.slice(0, 10)}</span>{" "}
<span className="inline-block">{text.slice(11)}</span>
</time>
);
}
/** Channel history is authoritative; local state holds drafts and request feedback only. */
export function CommunicationsConsole(props: CommunicationsConsoleProps) {
return <ConsoleWorkspace key={props.snapshot.id} {...props} />;
}
function ConsoleWorkspace({
snapshot,
selectedChannelId,
onSelectedChannelChange,
onAction,
}: CommunicationsConsoleProps) {
const instanceId = useId();
const [drafts, setDrafts] = useState<Record<string, Draft>>({});
const [pending, setPending] = useState<Record<string, string | undefined>>({});
const [feedback, setFeedback] = useState<Record<string, CommunicationsActionResult | undefined>>(
{},
);
const inFlight = useRef(new Set<string>());
const attempts = useRef(new Map<string, string>());
const sequence = useRef(0);
const conversation = useRef<HTMLElement>(null);
const composer = useRef<HTMLTextAreaElement>(null);
const messageList = useRef<HTMLOListElement>(null);
const rail = useRef<HTMLUListElement>(null);
// Where the message list was last left: at the newest message or not, and how many it held.
const nearEnd = useRef(true);
const listState = useRef<{ channelId: string | null; count: number }>({
channelId: null,
count: 0,
});
const [unseen, setUnseen] = useState(0);
const selection = useRef(selectedChannelId);
const selectionFocus = useRef<string | null>(null);
const latestRequested = useRef(false);
const returnFocus = useRef<{
channelId: string;
origin: Element | null;
target: "composer" | "conversation";
} | null>(null);
const channel = snapshot.channels.find((item) => item.id === selectedChannelId);
const connected = snapshot.connection === "connected";
const draft = channel ? (drafts[channel.id] ?? emptyDraft) : emptyDraft;
const channelPending = channel ? pending[channel.id] : undefined;
const result = channel ? feedback[channel.id] : undefined;
const messages = snapshot.messages
.filter((message) => message.channelId === channel?.id)
.sort((left, right) => left.sentAt - right.sentAt);
const needsAcknowledgement = (message: CommunicationsMessage) =>
message.sender.id !== snapshot.operator.id &&
message.delivery === "delivered" &&
message.acknowledgementRequested &&
!message.acknowledgement;
const awaitingOperator = messages.filter(needsAcknowledgement).length;
const channelId = channel?.id ?? null;
const messageCount = messages.length;
useLayoutEffect(() => {
selection.current = selectedChannelId;
if (selectionFocus.current !== null && selectionFocus.current === selectedChannelId) {
conversation.current?.focus();
selectionFocus.current = null;
}
const list = messageList.current;
const wantsLatest = latestRequested.current;
latestRequested.current = false;
const known = listState.current;
if (known.channelId !== channelId) {
// A channel opens at its newest message, where the operator's attention is needed.
listState.current = { channelId, count: messageCount };
nearEnd.current = true;
if (list) list.scrollTop = list.scrollHeight;
setUnseen(0);
} else {
const added = messageCount - known.count;
known.count = messageCount;
if (list && (wantsLatest || (added > 0 && nearEnd.current))) {
list.scrollTop = list.scrollHeight;
nearEnd.current = true;
setUnseen(0);
} else if (added > 0) {
// The operator is reading earlier messages: do not move the list under them, say so.
setUnseen((count) => count + added);
}
}
const requested = returnFocus.current;
if (requested && !pending[requested.channelId]) {
returnFocus.current = null;
// The browser may leave focus on the control it was on (a disabled one, in some engines)
// or drop it to the page; in either case the operator has not chosen to go elsewhere.
if (
requested.channelId === selectedChannelId &&
(document.activeElement === requested.origin || document.activeElement === document.body)
) {
(requested.target === "composer" ? composer.current : conversation.current)?.focus();
}
}
}, [selectedChannelId, channelId, messageCount, snapshot.messages, pending]);
// The channel list is a sideways strip on a narrow window: keep the open channel in view after
// a selection and after any resize, scrolling the strip only (never the page).
useLayoutEffect(() => {
const strip = rail.current;
if (!strip) return;
const reveal = () => {
const active = strip.querySelector<HTMLElement>('[aria-pressed="true"]');
if (!active || strip.scrollWidth <= strip.clientWidth) return;
const box = strip.getBoundingClientRect();
const item = active.getBoundingClientRect();
if (item.left < box.left) strip.scrollLeft -= box.left - item.left;
else if (item.right > box.right) strip.scrollLeft += item.right - box.right;
};
reveal();
const observer = new ResizeObserver(reveal);
observer.observe(strip);
return () => observer.disconnect();
}, [selectedChannelId]);
function jumpToLatest() {
const list = messageList.current;
if (!list) return;
list.scrollTop = list.scrollHeight;
nearEnd.current = true;
setUnseen(0);
list.focus({ preventScroll: true });
}
function showFirstAwaiting() {
const first = messages.find(needsAcknowledgement);
const control = first ? document.getElementById(`${instanceId}-ack-${first.id}`) : null;
control?.scrollIntoView?.({ block: "nearest" });
control?.focus();
}
function selectChannel(channelId: string) {
if (selectedChannelId === channelId) {
selectionFocus.current = null;
conversation.current?.focus();
return;
}
selectionFocus.current = channelId;
onSelectedChannelChange(channelId);
}
function updateDraft(next: Partial<Draft>) {
if (!channel) return;
setDrafts((current) => ({ ...current, [channel.id]: { ...draft, ...next } }));
}
async function act(
action:
| Omit<Extract<CommunicationsActionRequest, { type: "send" }>, "requestId">
| Omit<Extract<CommunicationsActionRequest, { type: "acknowledge" }>, "requestId">,
) {
if (!onAction || !connected || inFlight.current.has(action.channelId)) return;
const channelId = action.channelId;
const fingerprint = JSON.stringify(action);
const requestId =
attempts.current.get(fingerprint) ??
globalThis.crypto?.randomUUID?.() ??
`${instanceId}-${++sequence.current}`;
attempts.current.set(fingerprint, requestId);
inFlight.current.add(channelId);
setPending((current) => ({
...current,
[channelId]: action.type === "send" ? "send" : action.messageId,
}));
setFeedback((current) => ({ ...current, [channelId]: undefined }));
const origin = document.activeElement;
try {
const response = await onAction({ ...action, requestId });
setFeedback((current) => ({ ...current, [channelId]: response }));
// Closing this operation must not discard another payload's uncertain outcome.
attempts.current.delete(fingerprint);
if (response.kind === "accepted") {
if (action.type === "send") {
setDrafts((current) => ({ ...current, [channelId]: emptyDraft }));
if (selection.current === channelId) {
latestRequested.current = true;
returnFocus.current = { channelId, origin, target: "composer" };
}
} else if (selection.current === channelId) {
returnFocus.current = { channelId, origin, target: "conversation" };
}
}
} catch {
setFeedback((current) => ({
...current,
[channelId]: {
kind: "rejected",
message:
"The action could not be confirmed. Your draft is retained. Review channel history before retrying.",
},
}));
} finally {
inFlight.current.delete(channelId);
setPending((current) => ({ ...current, [channelId]: undefined }));
}
}
return (
<section
aria-label={snapshot.title}
className="w-full min-w-0 font-sans text-oprt-base normal-case tracking-normal text-oprt-text"
>
<header className="mb-3u flex flex-wrap items-start justify-between gap-2u">
<div className="min-w-0">
<h2 className="m-0 text-oprt-xl font-semibold normal-case tracking-normal">
{snapshot.title}
</h2>
<p className="m-0 mt-0.5u text-oprt-text-dim">{snapshot.location}</p>
</div>
<div className="flex flex-wrap items-center gap-2u pt-1u">
<Badge appearance="text" variant={connected ? "success" : "warning"}>
{connected ? "Relay connected" : "Connection lost"}
</Badge>
<Stamp at={snapshot.observedAt} className="font-mono text-oprt-text-dim" />
</div>
</header>
{!connected && (
<p
role="alert"
className="m-0 mb-2u border border-oprt-border bg-oprt-surface-2 p-2u text-oprt-warning"
>
Connection lost. Messages show the last received snapshot. Drafts remain editable; sending
and acknowledgements are unavailable until the connection returns.
</p>
)}
<div className="flex min-w-0 flex-wrap border border-oprt-border bg-oprt-surface-1">
<aside
aria-label="Channel navigation"
className="min-w-0 flex-[1_1_13rem] bg-oprt-surface-2"
>
<div className="flex items-baseline justify-between gap-2u border-b border-oprt-border px-2u py-2u">
<h3 className="m-0 text-oprt-md font-semibold normal-case">Channels</h3>
<span className="font-mono text-oprt-text-dim">
{String(snapshot.channels.length).padStart(2, "0")}
</span>
</div>
<nav aria-label="Communications channels">
<ul ref={rail} className="m-0 flex list-none overflow-x-auto p-0 sm:block">
{snapshot.channels.map((item) => {
const channelMessages = snapshot.messages.filter(
(message) => message.channelId === item.id,
);
const attention = channelMessages.filter(needsAcknowledgement).length;
const lastMessage = [...channelMessages].sort((a, b) => b.sentAt - a.sentAt)[0];
const hasDraft = Boolean(drafts[item.id]?.body);
const today = dayOf(snapshot.observedAt);
// The last message's time: "HH:MM UTC" today, with its date above when it is older.
const lastDay = lastMessage ? dayOf(lastMessage.sentAt) : today;
const badge = hasDraft
? "Draft saved"
: attention
? `${attention} to acknowledge`
: item.canPost
? `${channelMessages.length} ${channelMessages.length === 1 ? "message" : "messages"}`
: "Read only";
const isOpen = channel?.id === item.id;
return (
<li
key={item.id}
className="min-w-[11rem] shrink-0 border-b border-oprt-border sm:min-w-0"
>
<button
type="button"
// The name carries what the button shows, after the name the tests and
// readers expect first: the ID, the last message time and the badge.
aria-label={`${item.name} channel, ${item.id}${lastMessage ? `, last message ${lastDay === today ? "" : `${lastDay} `}${clock(lastMessage.sentAt, false)}` : ""}, ${badge}${attention && hasDraft ? `, ${attention} to acknowledge` : ""}`}
aria-pressed={isOpen}
onClick={() => selectChannel(item.id)}
// The open channel also gets a bar down its edge: a tint and a text color
// are not a shape, and the bar survives the focus outline.
className={`relative block w-full min-w-0 px-2u py-2u text-left hover:bg-oprt-surface-3 ${focus} ${isOpen ? "bg-oprt-surface-3 text-oprt-text before:absolute before:inset-y-0 before:left-0 before:w-[3px] before:bg-oprt-accent forced-colors:before:bg-[Highlight]" : "text-oprt-text-dim"}`}
>
<span className="flex min-w-0 items-baseline justify-between gap-1u">
<span className="break-words text-oprt-md font-medium">{item.name}</span>
{lastMessage && (
<time
dateTime={isoOf(lastMessage.sentAt)}
className="shrink-0 text-right font-mono text-oprt-sm text-oprt-text-dim"
>
{lastDay !== today && <span className="block">{lastDay}</span>}
<span className="inline-block">{clock(lastMessage.sentAt, false)}</span>
</time>
)}
</span>
<span className="mt-0.5u flex min-w-0 flex-wrap items-center justify-between gap-1u">
<span className="font-mono text-oprt-sm text-oprt-text-dim">{item.id}</span>
{hasDraft ? (
<Badge appearance="text" variant="info">
{badge}
</Badge>
) : attention ? (
<Badge appearance="text" variant="warning">
{badge}
</Badge>
) : (
<Badge appearance="text">{badge}</Badge>
)}
</span>
</button>
</li>
);
})}
</ul>
</nav>
<div className="flex flex-wrap items-baseline gap-x-2u gap-y-0.5u p-2u">
<p className="m-0 font-medium">{snapshot.operator.name}</p>
<p className="m-0 text-oprt-text-dim">{snapshot.operator.role}</p>
</div>
{channel && (
<details className="min-w-0 border-t border-oprt-border p-2u">
<summary className={`min-h-3u cursor-pointer font-medium ${focus}`}>
Channel details
</summary>
<div className="mt-2u">
<EntityPreview
headingLevel={4}
entity={{
id: channel.id,
name: channel.name,
typeLabel: "Support communications",
summary: channel.purpose,
facts: [
{ id: "lead", label: "Channel lead", value: channel.lead },
{ id: "operator", label: "Your identity", value: snapshot.operator.name },
{
id: "participants",
label: "Participants",
value: String(channel.participants.length),
},
{
id: "posting",
label: "Posting",
value: channel.canPost ? "Available to you" : "Read only",
},
],
quality: {
state: connected ? "current" : "stale",
source: snapshot.source,
updatedAt: snapshot.observedAt,
detail: connected
? "Latest supplied channel snapshot."
: "Connection lost; last received snapshot retained.",
},
}}
/>
<h4 className="m-0 mt-3u text-oprt-base font-medium normal-case">Participants</h4>
<ul className="m-0 mt-1u list-none space-y-1u p-0">
{channel.participants.map((person) => (
<li key={person.id} className="min-w-0 break-words">
<span className="block">{person.name}</span>
<span className="text-oprt-text-dim">{person.role}</span>
</li>
))}
</ul>
</div>
</details>
)}
</aside>
<section
ref={conversation}
tabIndex={-1}
aria-label="Channel conversation"
className={`min-w-0 flex-[4_1_29rem] border-l border-oprt-border ${focus}`}
>
{channel ? (
<>
<header className="flex flex-wrap items-center justify-between gap-1u border-b border-oprt-border px-3u py-2u">
<div className="min-w-0">
<h3 className="m-0 text-oprt-lg font-semibold normal-case tracking-normal">
{channel.name}
</h3>
<p className="m-0 mt-0.5u text-oprt-text-dim">{channel.purpose}</p>
</div>
<span className="font-mono text-oprt-sm text-oprt-text-dim">{channel.id}</span>
</header>
<div className="flex flex-wrap items-center justify-between gap-1u border-b border-oprt-border px-3u py-1u">
<span className="text-oprt-text-dim">
<span className="inline-block font-mono">{dayOf(snapshot.observedAt)}</span> · All
times UTC
</span>
<div className="flex flex-wrap items-center gap-1u">
<p aria-live="polite" className="m-0 text-oprt-text-dim">
{unseen > 0
? `${unseen} new ${unseen === 1 ? "message" : "messages"} below.`
: ""}
</p>
{unseen > 0 && (
<Button size="sm" variant="secondary" onClick={jumpToLatest}>
Jump to latest
</Button>
)}
{awaitingOperator > 0 && (
<Button size="sm" variant="tertiary" onClick={showFirstAwaiting}>
{awaitingOperator} awaiting your acknowledgement
</Button>
)}
</div>
</div>
{messages.length ? (
<ol
ref={messageList}
aria-label={`${channel.name} messages`}
tabIndex={0}
onScroll={(event) => {
const list = event.currentTarget;
nearEnd.current =
list.scrollHeight - list.scrollTop - list.clientHeight <= END_SLACK;
if (nearEnd.current) setUnseen(0);
}}
className={`m-0 max-h-[34rem] min-w-0 list-none overflow-y-auto p-0 ${focus}`}
>
{messages.map((message, index) => {
const ownMessage = message.sender.id === snapshot.operator.id;
// A new day starts with its date; the first message needs one only when it is
// not on the snapshot's day, which the strip above the list already names.
const day = dayOf(message.sentAt);
const previousDay = index > 0 ? dayOf(messages[index - 1]!.sentAt) : null;
const newDay =
previousDay === null
? day !== dayOf(snapshot.observedAt)
: day !== previousDay;
return (
<Fragment key={message.id}>
{newDay && (
<li className="border-b border-oprt-border bg-oprt-surface-2 px-3u py-1u font-mono text-oprt-sm text-oprt-text-dim">
{day}
</li>
)}
<li
className={`min-w-0 border-b border-oprt-border px-3u py-2u ${ownMessage ? "bg-oprt-surface-2" : ""}`}
>
<div className="flex flex-wrap items-baseline justify-between gap-x-2u gap-y-0.5u">
<div className="flex min-w-0 flex-wrap items-baseline gap-x-1u gap-y-0.5u">
<span className="break-words text-oprt-md font-semibold">
{message.sender.name}
</span>
<span className="text-oprt-text-dim">
{ownMessage ? "You" : message.sender.role}
</span>
</div>
<time
dateTime={isoOf(message.sentAt)}
className="whitespace-nowrap font-mono text-oprt-text-dim"
>
{clock(message.sentAt, true)}
</time>
</div>
<p className="m-0 mt-1u max-w-[72ch] whitespace-pre-wrap break-words text-oprt-md leading-relaxed [overflow-wrap:anywhere]">
{message.body}
</p>
<div className="mt-1u flex flex-wrap items-center justify-between gap-x-2u gap-y-1u">
<div className="flex min-w-0 flex-wrap items-center gap-x-2u gap-y-0.5u">
<span className="font-mono text-oprt-sm text-oprt-text-dim">
{message.id}
</span>
<Badge
appearance="text"
variant={
message.delivery === "failed"
? "error"
: message.delivery === "pending"
? "warning"
: "neutral"
}
>
{message.delivery === "delivered"
? "Delivered to channel"
: message.delivery === "pending"
? "Delivery pending"
: "Delivery failed"}
</Badge>
{message.acknowledgement ? (
<span className="text-oprt-success">
Acknowledged by {message.acknowledgement.by.name} ·{" "}
<time
dateTime={isoOf(message.acknowledgement.at)}
className="whitespace-nowrap font-mono"
>
{dayOf(message.acknowledgement.at) === day
? clock(message.acknowledgement.at, true)
: `${dayOf(message.acknowledgement.at)} ${clock(message.acknowledgement.at, true)}`}
</time>
</span>
) : message.acknowledgementRequested ? (
<Badge appearance="text" variant="warning">
{ownMessage
? "Awaiting acknowledgement"
: "Acknowledgement requested"}
</Badge>
) : (
<span className="text-oprt-sm text-oprt-text-dim">
No acknowledgement requested
</span>
)}
</div>
{needsAcknowledgement(message) && (
<Button
id={`${instanceId}-ack-${message.id}`}
variant="secondary"
size="sm"
aria-label={`Acknowledge message ${message.id}`}
disabled={!connected || !onAction}
// While a request is out the button says so but keeps focus: a
// disabled button can drop the operator's place to the page.
{...(channelPending
? { "aria-disabled": true, "data-disabled": "true" }
: {})}
onClick={() => {
if (channelPending) return;
void act({
type: "acknowledge",
channelId: channel.id,
messageId: message.id,
});
}}
>
{channelPending === message.id ? "Acknowledging…" : "Acknowledge"}
</Button>
)}
</div>
</li>
</Fragment>
);
})}
</ol>
) : (
<div className="px-3u py-5u">
<p className="m-0 text-oprt-md font-medium">No messages in {channel.name} yet.</p>
<p className="m-0 mt-1u text-oprt-text-dim">
Start a conversation with the channel participants.
</p>
</div>
)}
<div className="px-3u py-2u">
{channel.canPost ? (
<form
aria-label={`Compose to ${channel.name}`}
onSubmit={(event) => {
event.preventDefault();
if (!draft.body.trim() || channelPending) return;
void act({
type: "send",
channelId: channel.id,
body: draft.body.trim(),
acknowledgementRequested: draft.acknowledgementRequested,
});
}}
>
<Field
label={`Message to ${channel.name}`}
help={
connected
? "Enter adds a new line. Use Send message to submit."
: "Draft retained in this session. Sending resumes when the connection returns."
}
>
<Textarea
ref={composer}
rows={3}
maxLength={2_000}
value={draft.body}
disabled={!onAction}
// Read-only while a request is out, so a focused composer keeps focus.
readOnly={Boolean(channelPending)}
placeholder="Write an update for this channel…"
onChange={(event) => updateDraft({ body: event.target.value })}
/>
</Field>
<div className="mt-2u flex flex-wrap items-center justify-between gap-2u">
<div className="flex items-center gap-1u">
<Checkbox
id={`${instanceId}-acknowledgement`}
aria-label="Request acknowledgement"
checked={draft.acknowledgementRequested}
onCheckedChange={(checked) =>
updateDraft({ acknowledgementRequested: checked === true })
}
disabled={Boolean(channelPending) || !onAction}
/>
<label htmlFor={`${instanceId}-acknowledgement`} className="cursor-pointer">
Request acknowledgement
</label>
</div>
<div className="flex items-center gap-2u">
<span
className="font-mono text-oprt-sm text-oprt-text-dim"
aria-label={`${draft.body.length} of 2000 characters`}
>
{draft.body.length} / 2000
</span>
<Button
type="submit"
size="sm"
disabled={!connected || !onAction || !draft.body.trim()}
// Unavailable while the request is out, yet still focused: a disabled
// button can drop the operator's place to the page.
{...(channelPending
? { "aria-disabled": true, "data-disabled": "true" }
: {})}
>
{channelPending === "send" ? "Sending…" : "Send message"}
</Button>
</div>
</div>
{!onAction && (
<p className="m-0 mt-1u text-oprt-text-dim">
Posting is unavailable in this view.
</p>
)}
</form>
) : (
<p className="m-0 text-oprt-text-dim">
{channel.readOnlyReason ?? "This channel is read-only."}
</p>
)}
{/* Two regions that are always mounted, each for one outcome: a region whose role
changes, or one marked polite, is not reliably announced as an alert. */}
<p
role="status"
className={`m-0 text-oprt-text-dim ${result?.kind === "accepted" ? "mt-2u" : ""}`}
>
{result?.kind === "accepted" ? result.message : ""}
</p>
<p
role="alert"
className={`m-0 text-oprt-error ${result?.kind === "rejected" ? "mt-2u" : ""}`}
>
{result?.kind === "rejected" ? result.message : ""}
</p>
</div>
<footer className="flex flex-wrap items-center justify-between gap-1u border-t border-oprt-border px-3u py-1u text-oprt-sm text-oprt-text-dim">
<span>Source: {snapshot.source}</span>
<span>
Snapshot <Stamp at={snapshot.observedAt} className="font-mono" />
</span>
</footer>
</>
) : (
<p className="m-0 p-3u text-oprt-text-dim">Select a channel to view its messages.</p>
)}
</section>
</div>
</section>
);
}
patterns/operational-domain.ts
/** Fixture context used by reusable application recipes. */
export type OperationalDomain = "military" | "industrial";
export interface UtcInstantOptions {
/**
* Whether the milliseconds are shown. "auto" (the default) shows them only when the supplied
* instant carries a non-zero fraction, because sub-second timing matters only where it exists.
*/
milliseconds?: "auto" | "always" | "never";
}
const INSTANT =
/^(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2})(?:\.(\d{1,3}))?(Z|[+-]\d{2}:\d{2})$/;
/**
* Reads an ISO 8601 instant as "YYYY-MM-DD HH:MM:SS UTC", with ".mmm" after the seconds where the
* options ask for it. Text that is not a real instant (an invented date such as 30 February, or
* free text) is returned as supplied rather than reinterpreted. It never uses Intl, so the server
* and every browser print the same characters.
*/
export function formatUtcInstant(value: string, options: UtcInstantOptions = {}): string {
const parts = INSTANT.exec(value);
if (!parts) return value;
const [year, month, day, hour, minute, second] = parts.slice(1, 7).map(Number) as [
number,
number,
number,
number,
number,
number,
];
const calendar = new Date(Date.UTC(year, month - 1, day));
// Date rolls an invented day into the next month; compare it back to what was written.
if (
calendar.getUTCFullYear() !== year ||
calendar.getUTCMonth() !== month - 1 ||
calendar.getUTCDate() !== day ||
hour > 23 ||
minute > 59 ||
second > 59
)
return value;
const fraction = (parts[7] ?? "").padEnd(3, "0");
const parsed = new Date(`${value.slice(0, 19)}.${fraction}${parts[8]}`);
if (Number.isNaN(parsed.getTime())) return value;
const { milliseconds = "auto" } = options;
const showFraction = milliseconds === "always" || (milliseconds === "auto" && fraction !== "000");
const iso = parsed.toISOString();
return `${iso.slice(0, 10)} ${iso.slice(11, showFraction ? 23 : 19)} UTC`;
}
/**
* Reads epoch milliseconds as "YYYY-MM-DD HH:MM:SS UTC", with the same options as
* formatUtcInstant. A value that is not a real time reads "Unknown time" rather than throwing.
*/
export function formatUtcEpoch(ms: number, options: UtcInstantOptions = {}): string {
const date = new Date(ms);
if (!Number.isFinite(ms) || Number.isNaN(date.getTime())) return "Unknown time";
return formatUtcInstant(date.toISOString(), options);
}
patterns/communications-console/types.ts
export interface CommunicationsPerson {
id: string;
name: string;
role: string;
}
export interface CommunicationsChannel {
id: string;
name: string;
purpose: string;
lead: string;
participants: readonly CommunicationsPerson[];
canPost: boolean;
readOnlyReason?: string;
}
export interface CommunicationsMessage {
id: string;
channelId: string;
sender: CommunicationsPerson;
body: string;
sentAt: number;
delivery: "pending" | "delivered" | "failed";
acknowledgementRequested: boolean;
acknowledgement?: { by: CommunicationsPerson; at: number };
/** Application idempotency key, retained when an uncertain send is retried. */
requestId?: string;
}
export interface CommunicationsSnapshot {
/** Replacing this identity resets channel drafts and pending feedback. */
id: string;
title: string;
location: string;
source: string;
observedAt: number;
connection: "connected" | "disconnected";
operator: CommunicationsPerson;
channels: readonly CommunicationsChannel[];
messages: readonly CommunicationsMessage[];
}
export type CommunicationsActionRequest = {
requestId: string;
channelId: string;
} & (
| { type: "send"; body: string; acknowledgementRequested: boolean }
| { type: "acknowledge"; messageId: string }
);
export interface CommunicationsActionResult {
kind: "accepted" | "rejected";
message: string;
}
export interface CommunicationsConsoleProps {
snapshot: CommunicationsSnapshot;
selectedChannelId: string | null;
onSelectedChannelChange: (channelId: string) => void;
/** Publish authoritative messages separately. Keep requestId idempotent when retrying. */
onAction?: (
request: CommunicationsActionRequest,
) => CommunicationsActionResult | Promise<CommunicationsActionResult>;
}
patterns/communications-console/demo.tsx
"use client";
import { useRef, useState } from "react";
import { Badge, Button } from "@operator-ds/react";
import { CommunicationsConsole } from "./communications-console";
import { createCommunicationsSnapshot } from "./fixtures";
import { applyCommunicationsAction } from "./communications-state";
import type { CommunicationsSnapshot } from "./types";
export function CommunicationsConsoleDemo() {
const [snapshot, setSnapshot] = useState(createCommunicationsSnapshot);
const source = useRef(snapshot);
const [selectedChannelId, setSelectedChannelId] = useState<string | null>("NET-01");
const connected = snapshot.connection === "connected";
const receiptTarget = [...snapshot.messages]
.reverse()
.find(
(message) =>
message.channelId === selectedChannelId &&
message.sender.id === snapshot.operator.id &&
message.delivery === "delivered" &&
message.acknowledgementRequested &&
!message.acknowledgement,
);
function publish(next: CommunicationsSnapshot) {
source.current = next;
setSnapshot(next);
}
return (
<div className="flex w-full min-w-0 flex-col gap-2u">
<CommunicationsConsole
snapshot={snapshot}
selectedChannelId={selectedChannelId}
onSelectedChannelChange={setSelectedChannelId}
onAction={(request) => {
const next = applyCommunicationsAction(
source.current,
request,
source.current.observedAt + 60_000,
);
publish(next.snapshot);
return next.result;
}}
/>
<div className="flex flex-wrap items-center gap-x-2u gap-y-0.5u">
<Badge appearance="text" variant="neutral">
Fictional exercise
</Badge>
<span className="text-oprt-base text-oprt-text-dim">
Local messages only · No external service connected
</span>
</div>
<details className="min-w-0 border-t border-oprt-border pt-2u text-oprt-base">
<summary className="min-h-3u cursor-pointer font-medium text-oprt-text-dim focus-visible:outline focus-visible:outline-2 focus-visible:outline-oprt-border-focus">
Exercise controls
</summary>
<p className="m-0 mt-2u text-oprt-text-dim">
Change the local relay state or supply a recipient receipt. Restoring the connection does
not submit a saved draft.
</p>
<div className="mt-2u flex flex-wrap gap-1u">
<Button
variant="tertiary"
size="sm"
onClick={() =>
publish({
...source.current,
connection: connected ? "disconnected" : "connected",
observedAt: connected
? source.current.observedAt
: source.current.observedAt + 60_000,
})
}
>
{connected ? "Simulate connection loss" : "Restore connection"}
</Button>
<Button
variant="tertiary"
size="sm"
disabled={!connected || !receiptTarget}
onClick={() => {
if (!receiptTarget) return;
const channel = source.current.channels.find(
(item) => item.id === receiptTarget.channelId,
);
const recipient = channel?.participants.find(
(person) => person.id !== source.current.operator.id,
);
if (!recipient) return;
const at = source.current.observedAt + 60_000;
publish({
...source.current,
observedAt: at,
messages: source.current.messages.map((message) =>
message.id === receiptTarget.id
? { ...message, acknowledgement: { by: recipient, at } }
: message,
),
});
}}
>
Receive acknowledgement
</Button>
</div>
</details>
</div>
);
}
patterns/communications-console/fixtures.ts
import type { CommunicationsPerson, CommunicationsSnapshot } from "./types";
const operator: CommunicationsPerson = {
id: "watch-operator",
name: "Sgt Alex Morgan",
role: "Support watch",
};
const facilities: CommunicationsPerson = {
id: "facilities-desk",
name: "Facilities desk",
role: "Base services",
};
const transport: CommunicationsPerson = {
id: "transport-desk",
name: "Transport desk",
role: "Vehicle support",
};
const supervisor: CommunicationsPerson = {
id: "watch-supervisor",
name: "Lt Jordan Hayes",
role: "Watch supervisor",
};
const supply: CommunicationsPerson = {
id: "supply-desk",
name: "Supply desk",
role: "Stores and receipts",
};
const at = (time: string) => Date.parse(`2026-10-02T${time}:00Z`);
/** Fictional support traffic. Every action stays inside the current browser session. */
export function createCommunicationsSnapshot(): CommunicationsSnapshot {
return {
id: "kestrel-support-exercise",
title: "Communications Console",
location: "Camp Kestrel support watch",
source: "Kestrel exercise relay",
observedAt: at("09:20"),
connection: "connected",
operator,
channels: [
{
id: "NET-01",
name: "Base support",
purpose: "Coordinate base services and the next watch handover.",
lead: "Lt Jordan Hayes",
participants: [operator, facilities, transport, supervisor, supply],
canPost: true,
},
{
id: "NET-02",
name: "Transport",
purpose: "Vehicle readiness, driver handovers, and routine base movements.",
lead: "Transport desk",
participants: [operator, transport, supervisor],
canPost: true,
},
{
id: "NET-03",
name: "Facilities",
purpose: "Building access, inspections, and maintenance coordination.",
lead: "Facilities desk",
participants: [operator, facilities, supervisor],
canPost: true,
},
{
id: "NET-04",
name: "Supply",
purpose: "Record routine stores requests and confirm receipt of supplies.",
lead: "Supply desk",
participants: [operator, supply],
canPost: true,
},
{
id: "NET-05",
name: "Watch notices",
purpose: "Published notices for the current support watch.",
lead: "Lt Jordan Hayes",
participants: [operator, facilities, transport, supervisor, supply],
canPost: false,
readOnlyReason: "Only the watch supervisor can post to this channel.",
},
],
messages: [
{
id: "MSG-0410",
channelId: "NET-01",
sender: supervisor,
body: "Morning support handover is open. Keep facilities, transport, and supply updates in this channel.",
sentAt: at("09:02"),
delivery: "delivered",
acknowledgementRequested: false,
},
{
id: "MSG-0411",
channelId: "NET-01",
sender: operator,
body: "The standby generator inspection is complete. Facilities, confirm the log is ready for the 10:00 handover.",
sentAt: at("09:08"),
delivery: "delivered",
acknowledgementRequested: true,
},
{
id: "MSG-0412",
channelId: "NET-01",
sender: facilities,
body: "Please acknowledge the east service entrance reopening at 09:45, after the safety check. The inspection log is ready for handover.",
sentAt: at("09:16"),
delivery: "delivered",
acknowledgementRequested: true,
},
{
id: "MSG-0413",
channelId: "NET-02",
sender: transport,
body: "Two utility vehicles have completed their daily checks. Keys and inspection sheets are at the transport desk.",
sentAt: at("09:12"),
delivery: "delivered",
acknowledgementRequested: false,
},
{
id: "MSG-0414",
channelId: "NET-03",
sender: facilities,
body: "Workshop ventilation service is scheduled for 11:00. Please keep the service bay clear until the inspection is signed off.",
sentAt: at("09:14"),
delivery: "delivered",
acknowledgementRequested: true,
},
{
id: "MSG-0415",
channelId: "NET-05",
sender: supervisor,
body: "Support watch handover begins at 10:00 in the services office. Bring current inspection logs and outstanding supply requests.",
sentAt: at("09:18"),
delivery: "delivered",
acknowledgementRequested: false,
},
],
};
}
patterns/communications-console/communications-state.ts
import type {
CommunicationsActionRequest,
CommunicationsActionResult,
CommunicationsSnapshot,
} from "./types";
export function applyCommunicationsAction(
snapshot: CommunicationsSnapshot,
request: CommunicationsActionRequest,
at: number,
): { snapshot: CommunicationsSnapshot; result: CommunicationsActionResult } {
const reject = (message: string) => ({
snapshot,
result: { kind: "rejected" as const, message },
});
const channel = snapshot.channels.find((item) => item.id === request.channelId);
if (!channel) return reject("This channel is no longer available. Select another channel.");
if (!request.requestId.trim()) return reject("A request identity is required. Try again.");
// A transport retry can arrive after the first accepted response was lost.
if (request.type === "send") {
const previous = snapshot.messages.find((message) => message.requestId === request.requestId);
if (previous) {
if (
previous.channelId !== request.channelId ||
previous.body !== request.body.trim() ||
previous.acknowledgementRequested !== request.acknowledgementRequested
)
return reject("This request identity was already used for a different message.");
return {
snapshot,
result: {
kind: "accepted",
message: `${previous.id} was already accepted in this local exercise.`,
},
};
}
}
if (snapshot.connection !== "connected") {
return reject(
"Connection lost. Your draft is retained; restore the connection before sending.",
);
}
if (!Number.isFinite(at) || at < snapshot.observedAt) {
return reject("The action time is older than the source. Refresh the channel before retrying.");
}
if (!channel.participants.some((person) => person.id === snapshot.operator.id)) {
return reject("You are no longer a participant in this channel.");
}
if (request.type === "send") {
if (!channel.canPost) return reject(channel.readOnlyReason ?? "This channel is read-only.");
const body = request.body.trim();
if (!body || body.length > 2_000)
return reject("Write a message between 1 and 2,000 characters.");
const number =
Math.max(
0,
...snapshot.messages.map((message) => Number(message.id.replace(/^MSG-/, "")) || 0),
) + 1;
const id = `MSG-${String(number).padStart(4, "0")}`;
return {
snapshot: {
...snapshot,
observedAt: at,
messages: [
...snapshot.messages,
{
id,
channelId: channel.id,
sender: snapshot.operator,
body,
sentAt: at,
delivery: "delivered",
acknowledgementRequested: request.acknowledgementRequested,
requestId: request.requestId,
},
],
},
result: {
kind: "accepted",
message: `${id} delivered in this local exercise.${request.acknowledgementRequested ? " Recipient acknowledgement is still pending." : ""}`,
},
};
}
const message = snapshot.messages.find(
(item) => item.id === request.messageId && item.channelId === channel.id,
);
if (!message) return reject("The message is no longer available in this channel.");
if (message.sender.id === snapshot.operator.id)
return reject("The sender cannot acknowledge their own message.");
if (message.delivery !== "delivered")
return reject("Delivery must be confirmed before acknowledging this message.");
if (!message.acknowledgementRequested)
return reject("This message does not request an acknowledgement.");
if (message.acknowledgement) {
return {
snapshot,
result: { kind: "accepted", message: `${message.id} already has an acknowledgement.` },
};
}
return {
snapshot: {
...snapshot,
observedAt: at,
messages: snapshot.messages.map((item) =>
item.id === message.id ? { ...item, acknowledgement: { by: snapshot.operator, at } } : item,
),
},
result: {
kind: "accepted",
message: `${message.id} acknowledged by ${snapshot.operator.name} in this local exercise.`,
},
};
}