fix: harden single-machine load handling

loadtest/im-pressure/agent_history_test.go

@@ -2,7 +2,9 @@ package main
 
 import (
 	"errors"
+	"fmt"
 	"testing"
+	"time"
 )
 
 func TestHistoryQueriesForMessagesGroupsRangesByTopic(t *testing.T) {
@@ -51,6 +53,40 @@ func TestClassifyPublishErrorTreatsClosedConnectionAsUnknownSocketError(t *testi
 	}
 }
 
+func TestScenarioUsersScaleWithConfiguredCapacity(t *testing.T) {
+	tests := []struct {
+		users      int
+		group      int
+		mixedP2P   int
+		mixedGroup int
+	}{
+		{users: 1000, group: 500, mixedP2P: 300, mixedGroup: 250},
+		{users: 600, group: 300, mixedP2P: 180, mixedGroup: 150},
+	}
+	for _, tc := range tests {
+		if got := scaledUsers(tc.users, 1, 2); got != tc.group {
+			t.Fatalf("users=%d group=%d want=%d", tc.users, got, tc.group)
+		}
+		if got := scaledUsers(tc.users, 3, 10); got != tc.mixedP2P {
+			t.Fatalf("users=%d mixed p2p=%d want=%d", tc.users, got, tc.mixedP2P)
+		}
+		if got := scaledUsers(tc.users, 1, 4); got != tc.mixedGroup {
+			t.Fatalf("users=%d mixed group=%d want=%d", tc.users, got, tc.mixedGroup)
+		}
+	}
+}
+
+func TestNewHistoryQueryIncludesInterleavedSequenceRange(t *testing.T) {
+	messages := make([]AcceptedMessage, 10)
+	for i := range messages {
+		messages[i] = AcceptedMessage{ClientMid: fmt.Sprintf("mid-%d", i), Seq: int64(100 + i*2)}
+	}
+	query := newHistoryQuery(nil, "p2p-one", messages, 10)
+	if query.since != 100 || query.before != 119 || query.limit != 19 {
+		t.Fatalf("history query range=%d-%d limit=%d want=100-119/19", query.since, query.before, query.limit)
+	}
+}
+
 func TestMergeMessageLedgersPrefersPeerObservationAndAck(t *testing.T) {
 	senderEcho := AcceptedMessage{ClientMid: "mid-1", SenderMachine: "a", PeerMachine: "a", Seq: 10}
 	peerDelivery := AcceptedMessage{ClientMid: "mid-1", SenderMachine: "a", PeerMachine: "b", PeerIndex: 7, Seq: 10}
@@ -65,3 +101,15 @@ func TestMergeMessageLedgersPrefersPeerObservationAndAck(t *testing.T) {
 		t.Fatalf("ACK ledger was not authoritative: %+v", merged)
 	}
 }
+
+func TestCloseScheduleInterleavesLogicalAgents(t *testing.T) {
+	cfg := &Config{CloseRamp: "60s"}
+	intervalA, delayA := closeSchedule(cfg, "a", 601)
+	intervalB, delayB := closeSchedule(cfg, "b", 601)
+	if intervalA != 200*time.Millisecond || intervalB != intervalA {
+		t.Fatalf("intervals: a=%s b=%s, want 200ms", intervalA, intervalB)
+	}
+	if delayA != 0 || delayB != 100*time.Millisecond {
+		t.Fatalf("delays: a=%s b=%s, want 0/100ms", delayA, delayB)
+	}
+}