fix(alerts): исключить переходы между неоднозначными BGP peers

backend/src/services/alert-engine/bgp-signals.ts

@@ -8,14 +8,23 @@ export function isKnownBgpState(state: string): boolean {
 /** Runs arrive newest first. Keep current unknown, but use the last known previous state. */
 export function collectBgpSignalsFromRuns(runs: GreBgpSnapshotRunSnapshot[]): BgpPeerSignal[] {
   const byKey = new Map<string, BgpPeerSignal>()
+  const ambiguousHistory = new Set<string>()
   for (const run of runs) {
+    const batch = new Map<string, string>()
+    const duplicates = new Set<string>()
     for (const row of run.bgpPeers ?? []) {
       const key = String(row.key ?? "").trim()
       if (!key) continue
       const state = String(row.state ?? "").trim()
+      if (batch.has(key)) duplicates.add(key)
+      batch.set(key, state)
+    }
+    for (const [key, state] of batch) {
+      const duplicate = duplicates.has(key)
       const current = byKey.get(key)
-      if (!current) byKey.set(key, { key, state, prevState: null })
-      else if (current.prevState === null && isKnownBgpState(state)) current.prevState = state
+      if (!current) byKey.set(key, { key, state: duplicate ? "Unknown" : state, prevState: null })
+      else if (!duplicate && !ambiguousHistory.has(key) && current.prevState === null && isKnownBgpState(state)) current.prevState = state
+      if (duplicate) ambiguousHistory.add(key)
     }
   }
   return [...byKey.values()]

backend/src/services/alert-engine/evaluate-rule.test.ts

@@ -135,6 +135,19 @@ for (const [history, expectedPrevious, recoveryExpected] of [
   assert.equal(evaluateRule(recovery, emptySnap({ bgpSessions: signals })) !== null, recoveryExpected)
 }
 
+for (const pair of [["Established", "Idle"], ["Established", "Established"], ["Unknown", "Idle"]]) {
+  const runs = [{ bgpPeers: pair.map(state => ({ key: "srv: peer1", state })) }] as GreBgpSnapshotRunSnapshot[]
+  assert.deepEqual(collectBgpSignalsFromRuns(runs), [{ key: "srv: peer1", state: "Unknown", prevState: null }])
+}
+{
+  const runs = [
+    { bgpPeers: [{ key: "srv: peer1", state: "Established" }] },
+    { bgpPeers: [{ key: "srv: peer1", state: "Established" }, { key: "srv: peer1", state: "Idle" }] },
+    { bgpPeers: [{ key: "srv: peer1", state: "Idle" }] },
+  ] as GreBgpSnapshotRunSnapshot[]
+  assert.deepEqual(collectBgpSignalsFromRuns(runs), [{ key: "srv: peer1", state: "Established", prevState: null }])
+}
+
 {
   const r = rule({
     id: "srv-rec",