Index: binaries/data/mods/public/simulation/ai/common-api/gamestate.js
===================================================================
--- binaries/data/mods/public/simulation/ai/common-api/gamestate.js
+++ binaries/data/mods/public/simulation/ai/common-api/gamestate.js
@@ -35,6 +35,7 @@
 
 	let phaseData = {};
 	let phaseMap = {};
+
 	for (let techName of techs)
 	{
 		if (!techName.startsWith("phase"))
@@ -43,8 +44,9 @@
 
 		if (techData._definesPair)
 		{
-			// Randomly pick a non-disabled choice from the phase-pair.
-			techName = pickRandom([techData._template.top, techData._template.bottom].filter(tech => !this.playerData.disabledTechnologies[tech])) || techData._template.top;
+			// TODO: let ai decide at runtime which one wants
+			// Cannot call pickrandom because this function is called on rejoin and that causes oos (reverting rP20750)
+			techName = this.playerData.disabledTechnologies[techData._template.bottom] ? techData._template.top : techData._template.bottom;
 
 			let supersedes = techData._template.supersedes;
 			techData = clone(this.getTemplate(techName));
Index: binaries/data/mods/public/simulation/ai/petra/_petrabot.js
===================================================================
--- binaries/data/mods/public/simulation/ai/petra/_petrabot.js
+++ binaries/data/mods/public/simulation/ai/petra/_petrabot.js
@@ -55,7 +55,7 @@
 		this.queueManager.Deserialize(gameState, this.data.queueManager);
 		this.queues = this.queueManager.queues;
 
-		this.HQ = new PETRA.HQ(this.Config);
+		this.HQ = new PETRA.HQ(this.Config, true);
 		this.HQ.init(gameState, this.queues);
 		this.HQ.Deserialize(gameState, this.data.HQ);
 
Index: binaries/data/mods/public/simulation/ai/petra/attackManager.js
===================================================================
--- binaries/data/mods/public/simulation/ai/petra/attackManager.js
+++ binaries/data/mods/public/simulation/ai/petra/attackManager.js
@@ -778,7 +778,7 @@
 		this.upcomingAttacks[key] = [];
 		for (let dataAttack of data.upcomingAttacks[key])
 		{
-			let attack = new PETRA.AttackPlan(gameState, this.Config, dataAttack.properties.name);
+			let attack = new PETRA.AttackPlan(gameState, this.Config, dataAttack.properties.name, true);
 			attack.Deserialize(gameState, dataAttack);
 			attack.init(gameState);
 			this.upcomingAttacks[key].push(attack);
@@ -791,7 +791,7 @@
 		this.startedAttacks[key] = [];
 		for (let dataAttack of data.startedAttacks[key])
 		{
-			let attack = new PETRA.AttackPlan(gameState, this.Config, dataAttack.properties.name);
+			let attack = new PETRA.AttackPlan(gameState, this.Config, dataAttack.properties.name, true);
 			attack.Deserialize(gameState, dataAttack);
 			attack.init(gameState);
 			this.startedAttacks[key].push(attack);
Index: binaries/data/mods/public/simulation/ai/petra/attackPlan.js
===================================================================
--- binaries/data/mods/public/simulation/ai/petra/attackPlan.js
+++ binaries/data/mods/public/simulation/ai/petra/attackPlan.js
@@ -3,9 +3,10 @@
  * It deals with everything in an attack, from picking a target to picking a path to it
  * To making sure units are built, and pushing elements to the queue manager otherwise
  * It also handles the actual attack, though much work is needed on that.
+ * When deserialized is true, do not call any random function inside constructor as that causes oos.
  */
 
-PETRA.AttackPlan = function(gameState, Config, uniqueID, type, data)
+PETRA.AttackPlan = function(gameState, Config, uniqueID, type, data, deserialized)
 {
 	this.Config = Config;
 	this.name = uniqueID;
@@ -168,31 +169,35 @@
 		this.neededShips = 3;
 	}
 
-	// Put some randomness on the attack size
-	let variation = randFloat(0.8, 1.2);
-	// and lower priority and smaller sizes for easier difficulty levels
+
+	// Lower priority for easier difficulty levels
 	if (this.Config.difficulty < 2)
-	{
 		priority *= 0.6;
-		variation *= 0.5;
-	}
 	else if (this.Config.difficulty < 3)
-	{
 		priority *= 0.8;
-		variation *= 0.8;
-	}
-	for (let cat in this.unitStat)
-	{
-		this.unitStat[cat].targetSize = Math.round(variation * this.unitStat[cat].targetSize);
-		this.unitStat[cat].minSize = Math.min(this.unitStat[cat].minSize, this.unitStat[cat].targetSize);
-	}
 
-	// change the sizes according to max population
-	this.neededShips = Math.ceil(this.Config.popScaling * this.neededShips);
-	for (let cat in this.unitStat)
+	if (!deserialized)
 	{
-		this.unitStat[cat].targetSize = Math.round(this.Config.popScaling * this.unitStat[cat].targetSize);
-		this.unitStat[cat].minSize = Math.ceil(this.Config.popScaling * this.unitStat[cat].minSize);
+		// Put some randomness on the attack size
+		let variation = randFloat(0.8, 1.2);
+		// and lower sizes for easier difficulty levels
+		if (this.Config.difficulty < 2)
+			variation *= 0.5;
+		else if (this.Config.difficulty < 3)
+			variation *= 0.8;
+
+		for (let cat in this.unitStat)
+		{
+			this.unitStat[cat].targetSize = Math.round(variation * this.unitStat[cat].targetSize);
+			this.unitStat[cat].minSize = Math.min(this.unitStat[cat].minSize, this.unitStat[cat].targetSize);
+		}
+		// change the sizes according to max population
+		this.neededShips = Math.ceil(this.Config.popScaling * this.neededShips);
+		for (let cat in this.unitStat)
+		{
+			this.unitStat[cat].targetSize = Math.round(this.Config.popScaling * this.unitStat[cat].targetSize);
+			this.unitStat[cat].minSize = Math.ceil(this.Config.popScaling * this.unitStat[cat].minSize);
+		}
 	}
 
 	// TODO: there should probably be one queue per type of training building
Index: binaries/data/mods/public/simulation/ai/petra/diplomacyManager.js
===================================================================
--- binaries/data/mods/public/simulation/ai/petra/diplomacyManager.js
+++ binaries/data/mods/public/simulation/ai/petra/diplomacyManager.js
@@ -20,7 +20,7 @@
  * sent through AIInterface. It is expected that the other player will change their diplomacy stance to the stance
  * that we suggested within a period of time, or else the request will be deleted from this.sentDiplomacyRequests.
  */
-PETRA.DiplomacyManager = function(Config)
+PETRA.DiplomacyManager = function(Config, deserialized)
 {
 	this.Config = Config;
 	this.nextTributeUpdate = 90;
@@ -31,7 +31,9 @@
 	this.betrayWeighting = 150;
 	this.receivedDiplomacyRequests = new Map();
 	this.sentDiplomacyRequests = new Map();
-	this.sentDiplomacyRequestLapseTime = 120 + randFloat(10, 100);
+	this.sentDiplomacyRequestLapseTime = 120;
+	if (!deserialized)
+		this.sentDiplomacyRequestLapseTime = 120 + randFloat(10, 100);
 };
 
 /**
Index: binaries/data/mods/public/simulation/ai/petra/headquarters.js
===================================================================
--- binaries/data/mods/public/simulation/ai/petra/headquarters.js
+++ binaries/data/mods/public/simulation/ai/petra/headquarters.js
@@ -11,7 +11,7 @@
  *  -planning attacks -> attackManager
  *  -picking new CC locations.
  */
-PETRA.HQ = function(Config)
+PETRA.HQ = function(Config, deserialized)
 {
 	this.Config = Config;
 	this.phasing = 0;	// existing values: 0 means no, i > 0 means phasing towards phase i
@@ -42,7 +42,7 @@
 	this.tradeManager = new PETRA.TradeManager(this.Config);
 	this.navalManager = new PETRA.NavalManager(this.Config);
 	this.researchManager = new PETRA.ResearchManager(this.Config);
-	this.diplomacyManager = new PETRA.DiplomacyManager(this.Config);
+	this.diplomacyManager = new PETRA.DiplomacyManager(this.Config, deserialized);
 	this.garrisonManager = new PETRA.GarrisonManager(this.Config);
 	this.victoryManager = new PETRA.VictoryManager(this.Config);
 
@@ -2885,7 +2885,7 @@
 	this.researchManager = new PETRA.ResearchManager(this.Config);
 	this.researchManager.Deserialize(data.researchManager);
 
-	this.diplomacyManager = new PETRA.DiplomacyManager(this.Config);
+	this.diplomacyManager = new PETRA.DiplomacyManager(this.Config, true);
 	this.diplomacyManager.Deserialize(data.diplomacyManager);
 
 	this.garrisonManager = new PETRA.GarrisonManager(this.Config);