Link check-in and summary titles to their calendar events; add subscribe links

src/domain/weeklySummary.ts

@@ -134,6 +134,8 @@ export type WeeklySummaryEventInfo = {
    */
   endsAt: Date;
   location: string;
+  /** The Event's own `htmlLink`, if any — see domain/calendar.ts's MappedEvent. */
+  calendarLink: string | null;
 };
 
 export const DATE_FMT: Intl.DateTimeFormatOptions = {
@@ -158,9 +160,16 @@ function formatWhen(info: WeeklySummaryEventInfo): string {
   return `${info.startsAt.toLocaleDateString("en-US", DATE_FMT)} – ${inclusiveEnd.toLocaleDateString("en-US", DATE_FMT)}`;
 }
 
+/** Bolded, and linked to the calendar event when a link is known. */
+function linkedTitle(info: WeeklySummaryEventInfo): string {
+  return info.calendarLink
+    ? `<${info.calendarLink}|*${info.title}*>`
+    : `*${info.title}*`;
+}
+
 /** One event's line: title, when, and location — the building block every render case shares. */
 export function formatWeeklySummaryLine(info: WeeklySummaryEventInfo): string {
-  const parts = [`*${info.title}*`, formatWhen(info)];
+  const parts = [linkedTitle(info), formatWhen(info)];
   if (info.location) parts.push(`📍 ${info.location}`);
   return parts.join(" — ");
 }
@@ -219,33 +228,55 @@ export type WeeklySummaryLineEntry = {
   text: string;
 };
 
+/**
+ * The standard Google Calendar "add this calendar" URL for a calendar id, or
+ * `undefined` when there's no id (a calendar setting left unconfigured) —
+ * every caller can pass a `getSetting(...)` result straight through without
+ * its own null check. Whether the link actually grants access depends
+ * entirely on that calendar's own sharing settings in Google Calendar —
+ * hawk-bot has no say in that, it just builds the URL a person would need.
+ */
+export function calendarSubscribeLink(
+  calendarId: string | null | undefined
+): string | undefined {
+  if (!calendarId) return undefined;
+  return `https://calendar.google.com/calendar/u/0/r?cid=${encodeURIComponent(calendarId)}`;
+}
+
 /**
  * Assembles the full message body, sorted chronologically regardless of
  * input order. `label` and `emptyText` default to the Team Meeting Weekly
  * Summary's own wording; the Informational reply and Mentor/Teacher Weekly
  * Summary override `label` so each reads as its own digest rather than a
- * repeat of "This Week".
+ * repeat of "This Week". `subscribeLink`, when given, appends a footer line
+ * — every rebuild passes it again, same as every other part of the message,
+ * since a `chat.update` always replaces the full text.
  */
 export function assembleWeeklySummaryMessage(args: {
   weekStart: Date;
   weekEnd: Date;
   entries: readonly WeeklySummaryLineEntry[];
   label?: string;
   emptyText?: string;
+  subscribeLink?: string;
 }): string {
   const lastDay = new Date(args.weekEnd.getTime() - DAY_MS);
   const label = args.label ?? "This Week";
   const header = `*${label}* — ${args.weekStart.toLocaleDateString("en-US", DATE_FMT)} to ${lastDay.toLocaleDateString("en-US", DATE_FMT)}`;
+  const footer = args.subscribeLink
+    ? [`📅 <${args.subscribeLink}|Subscribe to this calendar>`]
+    : [];
 
   if (args.entries.length === 0) {
     return [
       header,
       args.emptyText ?? "_Nothing on the calendar this week._",
+      ...footer,
     ].join("\n\n");
   }
 
   const sorted = [...args.entries].sort(
     (a, b) => a.sortKey.getTime() - b.sortKey.getTime()
   );
-  return [header, ...sorted.map((e) => e.text)].join("\n\n");
+  return [header, ...sorted.map((e) => e.text), ...footer].join("\n\n");
 }

src/mentorSummary.ts

@@ -1,6 +1,7 @@
 import type { WebClient } from "@slack/web-api";
 import {
   assembleWeeklySummaryMessage,
+  calendarSubscribeLink,
   formatWeeklySummaryLine,
   isWeeklySummaryDue,
   resolveWeeklySummaryTiming,
@@ -56,6 +57,7 @@ export async function postDueMentorSummary(client: WebClient): Promise<void> {
     entries,
     label: "Mentor/Teacher Calendar",
     emptyText: "_Nothing on the Mentor/Teacher Calendar these two weeks._",
+    subscribeLink: calendarSubscribeLink(calendarId),
   });
 
   const { channel, ts } = await postWeeklySummary(client, channelId, text);

src/slack/checkin.ts

@@ -50,6 +50,13 @@ function meetingDetailBodyLines(event: EventRow): string[] {
   return lines;
 }
 
+/** Bolded, and linked to the calendar event when the Event has one. */
+function linkedTitle(event: EventRow): string {
+  return event.calendar_link
+    ? `<${event.calendar_link}|*${event.title}*>`
+    : `*${event.title}*`;
+}
+
 /**
  * Title, when, where, and description — the part of the post worth keeping
  * even once it's removed. `updateNote`, when given, marks the title line as
@@ -58,8 +65,8 @@ function meetingDetailBodyLines(event: EventRow): string[] {
  */
 function meetingDetailsText(event: EventRow, updateNote?: string): string {
   const titleLine = updateNote
-    ? `<!channel> ✏️ *${event.title}* _(updated: ${updateNote})_`
-    : `<!channel> *${event.title}*`;
+    ? `<!channel> ✏️ ${linkedTitle(event)} _(updated: ${updateNote})_`
+    : `<!channel> ${linkedTitle(event)}`;
   return [titleLine, ...meetingDetailBodyLines(event)].join("\n");
 }
 
@@ -77,7 +84,7 @@ function checkinMessageText(event: EventRow): string {
  * still happened.
  */
 export function lockedCheckinMessageText(event: EventRow): string {
-  const titleLine = `✅ *${event.title}* — attendance closed`;
+  const titleLine = `✅ ${linkedTitle(event)} — attendance closed`;
   return [titleLine, ...meetingDetailBodyLines(event)].join("\n");
 }
 
@@ -294,7 +301,7 @@ export async function announceEventRemoved(
     channel: event.checkin_channel,
     ts: event.checkin_message_ts,
     text: [
-      `🚫 *${event.title}* — this meeting has been removed.`,
+      `🚫 ${linkedTitle(event)} — this meeting has been removed.`,
       "",
       strikethroughLines(meetingDetailsText(event)),
     ].join("\n"),

src/weeklySummary.ts

@@ -1,6 +1,7 @@
 import type { WebClient } from "@slack/web-api";
 import {
   assembleWeeklySummaryMessage,
+  calendarSubscribeLink,
   formatWeeklySummaryLine,
   isWeeklySummaryDue,
   isWithinWeek,
@@ -48,6 +49,7 @@ export function toWeeklySummaryEventInfo(
     startsAt: new Date(row.starts_at),
     endsAt: new Date(row.ends_at),
     location: row.location,
+    calendarLink: row.calendar_link,
   };
 }
 
@@ -61,15 +63,25 @@ type SummaryItemSnapshot = Pick<
   | "snapshot_location"
 >;
 
+/**
+ * `calendarLink` isn't itself part of the stored snapshot (the snapshot
+ * table only tracks the fields Weekly Summary Change Reflection diffs) — it
+ * comes from the same underlying Event's current `calendar_link` instead,
+ * since a Google Calendar event's own link doesn't change when its fields
+ * do, so it's exactly as valid for the "as first shown" struck-through side
+ * of an edit as for the current side.
+ */
 function snapshotToEventInfo(
-  item: SummaryItemSnapshot
+  item: SummaryItemSnapshot,
+  calendarLink: string | null
 ): WeeklySummaryEventInfo {
   return {
     title: item.snapshot_title,
     meetingType: item.snapshot_meeting_type,
     startsAt: new Date(item.snapshot_starts_at),
     endsAt: new Date(item.snapshot_ends_at),
     location: item.snapshot_location,
+    calendarLink,
   };
 }
 
@@ -127,16 +139,22 @@ function buildEntriesFromItems(
 ): WeeklySummaryLineEntry[] {
   const entries: WeeklySummaryLineEntry[] = [];
   for (const item of items) {
-    const snapshotInfo = snapshotToEventInfo(item);
-    const event = item.removed ? undefined : getEvent(item.event_id);
+    // Fetched even when already `removed` — the row (and its
+    // `calendar_link`) still exists, only `removed_at` gets set.
+    const liveEvent = getEvent(item.event_id);
+    const snapshotInfo = snapshotToEventInfo(
+      item,
+      liveEvent?.calendar_link ?? null
+    );
 
-    if (!event) {
+    if (item.removed || !liveEvent) {
       entries.push({
         sortKey: snapshotInfo.startsAt,
         text: renderRemovedLine(snapshotInfo),
       });
       continue;
     }
+    const event = liveEvent;
 
     const currentInfo = toWeeklySummaryEventInfo(event);
     if (item.added_mid_week) {
@@ -172,6 +190,9 @@ async function rebuildAndUpdateWeeklySummary(
     weekStart: new Date(summary.week_start),
     weekEnd: new Date(summary.week_end),
     entries,
+    subscribeLink: calendarSubscribeLink(
+      getSetting("team_meeting_calendar_id")
+    ),
   });
   await updateWeeklySummary(client, summary.channel, summary.message_ts, text);
 }
@@ -191,6 +212,9 @@ async function rebuildAndUpdateInformationalReply(
     weekEnd: new Date(summary.week_end),
     entries,
     label: "Informational Calendar",
+    subscribeLink: calendarSubscribeLink(
+      getSetting("informational_calendar_id")
+    ),
   });
   await updateWeeklySummary(
     client,
@@ -213,7 +237,8 @@ async function reflectInformationalReplyChange(
   event: EventRow,
   kind: "changed" | "removed"
 ): Promise<void> {
-  if (!getSetting("informational_calendar_id")) return;
+  const calendarId = getSetting("informational_calendar_id");
+  if (!calendarId) return;
 
   const summary = getMostRecentWeeklySummary();
   if (!summary) return;
@@ -243,6 +268,7 @@ async function reflectInformationalReplyChange(
       weekEnd: range.end,
       entries,
       label: "Informational Calendar",
+      subscribeLink: calendarSubscribeLink(calendarId),
     });
     await postInformationalReply(
       client,
@@ -352,6 +378,9 @@ export async function postDueWeeklySummary(client: WebClient): Promise<void> {
     weekStart: start,
     weekEnd: end,
     entries,
+    subscribeLink: calendarSubscribeLink(
+      getSetting("team_meeting_calendar_id")
+    ),
   });
 
   const { channel, ts } = await postWeeklySummary(client, channelId, text);
@@ -373,7 +402,8 @@ export async function postDueWeeklySummary(client: WebClient): Promise<void> {
     eventCount: events.length,
   });
 
-  if (getSetting("informational_calendar_id")) {
+  const informationalCalendarId = getSetting("informational_calendar_id");
+  if (informationalCalendarId) {
     const infoEvents = listEventsStartingInRange(
       start.toISOString(),
       end.toISOString(),
@@ -389,6 +419,7 @@ export async function postDueWeeklySummary(client: WebClient): Promise<void> {
         weekEnd: end,
         entries: infoEntries,
         label: "Informational Calendar",
+        subscribeLink: calendarSubscribeLink(informationalCalendarId),
       });
       await postInformationalReply(client, channel, ts, infoText)
         .then(({ channel: replyChannel, ts: replyTs }) => {

test/checkin.test.ts

@@ -65,3 +65,19 @@ test("the locked message skips an empty location and description", () => {
   assert.doesNotMatch(text, /📍/);
   assert.equal(text.split("\n").length, 2);
 });
+
+test("the locked message links the title when the Event has a calendar link", () => {
+  const text = lockedCheckinMessageText({
+    ...baseEvent,
+    calendar_link: "https://calendar.google.com/event?eid=abc123",
+  });
+  assert.match(
+    text,
+    /^✅ <https:\/\/calendar\.google\.com\/event\?eid=abc123\|\*Team Meeting\*> — attendance closed/
+  );
+});
+
+test("the locked message shows a plain bolded title when there's no calendar link", () => {
+  const text = lockedCheckinMessageText(baseEvent);
+  assert.match(text, /^✅ \*Team Meeting\* — attendance closed/);
+});

test/weeklySummary.test.ts

@@ -3,6 +3,7 @@ import { test } from "node:test";
 import {
   DEFAULT_WEEKLY_SUMMARY_TIMING,
   assembleWeeklySummaryMessage,
+  calendarSubscribeLink,
   formatWeeklySummaryLine,
   isWeeklySummaryDue,
   isWithinWeek,
@@ -150,6 +151,7 @@ const hourlyInfo: WeeklySummaryEventInfo = {
   startsAt: new Date("2026-01-06T18:00:00Z"),
   endsAt: new Date("2026-01-06T20:00:00Z"),
   location: "Room 204",
+  calendarLink: null,
 };
 
 const allDayInfo: WeeklySummaryEventInfo = {
@@ -158,6 +160,7 @@ const allDayInfo: WeeklySummaryEventInfo = {
   startsAt: new Date("2026-01-10T00:00:00Z"),
   endsAt: new Date("2026-01-11T00:00:00Z"),
   location: "",
+  calendarLink: null,
 };
 
 const multiDayInfo: WeeklySummaryEventInfo = {
@@ -166,6 +169,7 @@ const multiDayInfo: WeeklySummaryEventInfo = {
   startsAt: new Date("2026-03-05T00:00:00Z"),
   endsAt: new Date("2026-03-08T00:00:00Z"), // exclusive, per Google's convention
   location: "Convention Center",
+  calendarLink: null,
 };
 
 test("an Hourly line shows the date, time range, and location", () => {
@@ -272,3 +276,55 @@ test("changed fields names exactly the displayed fields that differ", () => {
     "location",
   ]);
 });
+
+test("a line links the title when the Event has a calendar link", () => {
+  const linked: WeeklySummaryEventInfo = {
+    ...hourlyInfo,
+    calendarLink: "https://calendar.google.com/event?eid=abc123",
+  };
+  const line = formatWeeklySummaryLine(linked);
+  assert.match(
+    line,
+    /^<https:\/\/calendar\.google\.com\/event\?eid=abc123\|\*Team Meeting\*>/
+  );
+});
+
+test("a line shows a plain bolded title when there's no calendar link", () => {
+  const line = formatWeeklySummaryLine(hourlyInfo);
+  assert.match(line, /^\*Team Meeting\*/);
+  assert.doesNotMatch(line, /</);
+});
+
+test("the subscribe link is the standard Google Calendar 'add this calendar' URL", () => {
+  assert.equal(
+    calendarSubscribeLink("team@group.calendar.google.com"),
+    "https://calendar.google.com/calendar/u/0/r?cid=team%40group.calendar.google.com"
+  );
+});
+
+test("no calendar id means no subscribe link", () => {
+  assert.equal(calendarSubscribeLink(null), undefined);
+  assert.equal(calendarSubscribeLink(undefined), undefined);
+});
+
+test("a subscribe link appends a footer line to the assembled message", () => {
+  const message = assembleWeeklySummaryMessage({
+    weekStart: new Date("2026-01-05T00:00:00Z"),
+    weekEnd: new Date("2026-01-12T00:00:00Z"),
+    entries: [],
+    subscribeLink: "https://calendar.google.com/calendar/u/0/r?cid=abc",
+  });
+  assert.match(
+    message,
+    /📅 <https:\/\/calendar\.google\.com\/calendar\/u\/0\/r\?cid=abc\|Subscribe to this calendar>$/
+  );
+});
+
+test("no subscribe link means no footer line", () => {
+  const message = assembleWeeklySummaryMessage({
+    weekStart: new Date("2026-01-05T00:00:00Z"),
+    weekEnd: new Date("2026-01-12T00:00:00Z"),
+    entries: [],
+  });
+  assert.doesNotMatch(message, /📅/);
+});