fix(integrations): send no recovery for an incident the first run recorded silently

The watchdog's first pass after a deploy records standing incidents as
announced without paging. Their end then sent a recovery note for
something the operator was never told about. Such incidents now carry
the epoch as their announcement time, which no real announcement can
have, and close without a note.

src/lib/integrations/__tests__/watchdog-classify.test.ts

@@ -4,6 +4,7 @@ import {
   NORMAL_DELIVERY_MIN_DAYS,
   SOURCE_PROFILES,
   classifySilence,
+  FIRST_RUN_ALERTED_AT,
   currentIncident,
   decideWatchTransition,
   type WatchRow,
@@ -293,6 +294,27 @@ describe("currentIncident", () => {
   });
 });
 
+describe("decideWatchTransition: an incident recorded on the first run", () => {
+  it("closes without a recovery note, since none was ever sent", () => {
+    expect(
+      decideWatchTransition({
+        row: {
+          silentSince: ago(30),
+          incidentReason: "unexpected_silence",
+          incidentOpenedAt: ago(2),
+          alertedAt: FIRST_RUN_ALERTED_AT,
+        },
+        incident: null,
+        ledgerAlerted: false,
+      }),
+    ).toEqual({
+      kind: "close",
+      notify: false,
+      previousReason: "unexpected_silence",
+    });
+  });
+});
+
 describe("decideWatchTransition", () => {
   const incident = { reason: "unexpected_silence" as const, since: ago(30) };
 

src/lib/integrations/watchdog-classify.ts

@@ -189,6 +189,22 @@ export function currentIncident(input: {
   return null;
 }
 
+/**
+ * The `alertedAt` an incident gets when the watchdog's first pass after a
+ * deploy found it already standing: counted as announced, so it is never
+ * paged, but never actually sent either, so its end sends no recovery note.
+ * The epoch, because no real announcement can carry it, and it keeps the
+ * marker inside the existing row.
+ */
+export const FIRST_RUN_ALERTED_AT = new Date(0);
+
+/** Whether an `alertedAt` records a message that was really sent. */
+export function wasAnnounced(alertedAt: Date | null | undefined): boolean {
+  return (
+    alertedAt != null && alertedAt.getTime() !== FIRST_RUN_ALERTED_AT.getTime()
+  );
+}
+
 export type WatchTransition =
   /** No incident before, none now. */
   | { kind: "none" }
@@ -220,7 +236,7 @@ export function decideWatchTransition(input: {
   if (input.incident === null) {
     return {
       kind: "close",
-      notify: input.row?.alertedAt != null,
+      notify: wasAnnounced(input.row?.alertedAt),
       previousReason: open,
     };
   }

src/lib/integrations/watchdog.ts

@@ -31,6 +31,7 @@ import {
 } from "./connection-health-load";
 import { INTEGRATION_MEASUREMENT_SOURCE } from "./metric-freshness";
 import {
+  FIRST_RUN_ALERTED_AT,
   HISTORY_DAYS,
   SOURCE_PROFILES,
   classifySilence,
@@ -529,8 +530,9 @@ async function watchConnection(input: {
       incidentOpenedAt = now;
       if (summary.firstRun) {
         // Standing since before the watchdog first looked: recorded as
-        // announced, not paged (see `WatchdogSummary.firstRun`).
-        alertedAt = now;
+        // announced, not paged (see `WatchdogSummary.firstRun`), and marked
+        // so its end sends no recovery note either.
+        alertedAt = FIRST_RUN_ALERTED_AT;
       } else {
         announce(transition.reason, transition.since);
       }