ue-networking-replication

Name: ue-networking-replication
Author: quodsoler

544installs39forks

How to install ue-networking-replication?

quodsoler/unreal-engine-skills/ue-networking-replication

$npx -y skills add quodsoler/unreal-engine-skills --skill ue-networking-replication

Installs into the current project.

Summary

Use this skill when working on multiplayer networking, replication, RPC calls, net role logic, server/client authority, prediction, or synchronizing game state. Also use when the user mentions 'DOREPLIFETIME', 'dedicated server', 'replicated', or 'net role'. See references/replic

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SKILL.md

1	# UE Networking & Replication
2
3	You are an expert in Unreal Engine's networking and replication systems.
4
5	## Context Check
6
7	Read `.agents/ue-project-context.md` for this project's multiplayer configuration.
8	Look for: server topology (dedicated, listen, P2P), player count, replicated classes,
9	and any custom net drivers.
10
11	If the context file is absent, ask:
12	1. Server topology? (dedicated, listen, P2P)
13	2. Maximum player count per session?
14	3. Which actors or components need to replicate data?
15	4. Are you using Gameplay Ability System (GAS)?
16
17	---
18
19	## Net Roles and Authority
20
21	UE uses a server-authoritative model: the server is the source of truth for game state.
22	Clients predict locally and reconcile with server corrections.
23
24	Every actor on every machine has a local role and a remote role (`ENetRole`).
25
26	```
27	ROLE_Authority — owns and can modify this actor (server for replicated actors)
28	ROLE_AutonomousProxy — client copy of the locally controlled pawn
29	ROLE_SimulatedProxy — client copy of another player's actor; engine interpolates state
30	ROLE_None — not replicated
31	```
32
33	From `Actor.h`:
34	```cpp
35	ENetRole GetLocalRole() const { return Role; } // role on current machine
36	ENetRole GetRemoteRole() const; // role the other end sees
37	bool HasAuthority() const { return (GetLocalRole() == ROLE_Authority); }
38	```
39
40	Net modes: `NM_Standalone`, `NM_DedicatedServer`, `NM_ListenServer`, `NM_Client`.
41
42	Role matrix for a replicated Pawn:
43
44	\| Machine \| GetLocalRole() \| GetRemoteRole() \|
45	\|----------------\|----------------------\|-----------------------------------------\|
46	\| Server \| ROLE_Authority \| ROLE_AutonomousProxy or SimulatedProxy \|
47	\| Owning Client \| ROLE_AutonomousProxy \| ROLE_Authority \|
48	\| Other Clients \| ROLE_SimulatedProxy \| ROLE_Authority \|
49
50	Listen-server caveat: the host is both `ROLE_Authority` and locally controlled.
51	Use `IsLocallyControlled()` to distinguish logic that should skip the host player.
52
53	---
54
55	## UNetDriver
56
57	`UNetDriver` is the core transport class responsible for managing all network connections and
58	packet delivery for a world. It owns the list of `UNetConnection` objects and drives the
59	replication tick. Access it via `UWorld::GetNetDriver()`.
60
61	```cpp
62	UNetDriver* Driver = GetWorld()->GetNetDriver();
63	// Driver->ClientConnections — all connected clients (server-side)
64	// Driver->ServerConnection — connection to server (client-side)
65	```
66
67	For most gameplay code you never interact with `UNetDriver` directly; it is relevant when
68	writing custom net drivers, profiling connection state, or debugging packet loss.
69
70	---
71
72	## Property Replication
73
74	### Actor Setup
75
76	```cpp
77	AMyActor::AMyActor()
78	{
79	bReplicates = true; // AActor::SetReplicates() also available at runtime
80	SetReplicateMovement(true); // replicates FRepMovement (location/rotation/velocity)
81	SetNetUpdateFrequency(10.f); // checks per second
82	SetMinNetUpdateFrequency(2.f); // floor when nothing changes
83	NetPriority = 1.0f; // higher = preferred when bandwidth is saturated
84	}
85	```
86
87	From `Actor.h`: `SetReplicates`, `SetReplicateMovement`, `SetNetUpdateFrequency`,
88	`SetMinNetUpdateFrequency`, and `SetNetCullDistanceSquared` are all `ENGINE_API`.
89
90	FRepMovement: when `bReplicateMovement = true`, the engine serializes position,
91	velocity, and rotation into an `FRepMovement` struct (declared in `Actor.h`) and
92	sends it to simulated proxies. `UCharacterMovementComponent` bypasses this with its
93	own prediction-based replication; it writes compressed moves via `FSavedMove_Character`
94	and reconciles them server-side, so `SetReplicateMovement(false)` is the correct
95	default for characters using CMC.
96
97	### Declaring Properties
98
99	```cpp
100	UPROPERTY(Replicated)
101	int32 Health;
102
103	UPROPERTY(ReplicatedUsing = OnRep_State)
104	EMyState State;
105
106	UFUNCTION()
107	void OnRep_State(EMyState PreviousState); // old value passed as optional parameter
108	```
109
110	### GetLifetimeReplicatedProps
111
112	```cpp
113	// MyActor.cpp
114	#include "Net/UnrealNetwork.h"
115
116	void AMyActor::GetLifetimeReplicatedProps(
117	TArray<FLifetimeProperty>& OutLifetimeProps) const
118	{
119	Super::GetLifetimeReplicatedProps(OutLifetimeProps); // NEVER omit this
120	DOREPLIFETIME(AMyActor, Health);
121	DOREPLIFETIME_CONDITION(AMyActor, State, COND_OwnerOnly);
122	DOREPLIFETIME_CONDITION(AMyActor, SimData, COND_SimulatedOnly);
123	DOREPLIFETIME_CONDITION(AMyActor, Ini

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ue-networking-replication

544installs39forks

View on GitHub

How to install ue-networking-replication?

quodsoler/unreal-engine-skills/ue-networking-replication

$npx -y skills add quodsoler/unreal-engine-skills --skill ue-networking-replication

Installs into the current project.

Summary

Files · 1

View on GitHub

SKILL.md

1	# UE Networking & Replication
2
3	You are an expert in Unreal Engine's networking and replication systems.
4
5	## Context Check
6
7	Read `.agents/ue-project-context.md` for this project's multiplayer configuration.
8	Look for: server topology (dedicated, listen, P2P), player count, replicated classes,
9	and any custom net drivers.
10
11	If the context file is absent, ask:
12	1. Server topology? (dedicated, listen, P2P)
13	2. Maximum player count per session?
14	3. Which actors or components need to replicate data?
15	4. Are you using Gameplay Ability System (GAS)?
16
17	---
18
19	## Net Roles and Authority
20
21	UE uses a server-authoritative model: the server is the source of truth for game state.
22	Clients predict locally and reconcile with server corrections.
23
24	Every actor on every machine has a local role and a remote role (`ENetRole`).
25
26	```
27	ROLE_Authority — owns and can modify this actor (server for replicated actors)
28	ROLE_AutonomousProxy — client copy of the locally controlled pawn
29	ROLE_SimulatedProxy — client copy of another player's actor; engine interpolates state
30	ROLE_None — not replicated
31	```
32
33	From `Actor.h`:
34	```cpp
35	ENetRole GetLocalRole() const { return Role; } // role on current machine
36	ENetRole GetRemoteRole() const; // role the other end sees
37	bool HasAuthority() const { return (GetLocalRole() == ROLE_Authority); }
38	```
39
40	Net modes: `NM_Standalone`, `NM_DedicatedServer`, `NM_ListenServer`, `NM_Client`.
41
42	Role matrix for a replicated Pawn:
43
44	\| Machine \| GetLocalRole() \| GetRemoteRole() \|
45	\|----------------\|----------------------\|-----------------------------------------\|
46	\| Server \| ROLE_Authority \| ROLE_AutonomousProxy or SimulatedProxy \|
47	\| Owning Client \| ROLE_AutonomousProxy \| ROLE_Authority \|
48	\| Other Clients \| ROLE_SimulatedProxy \| ROLE_Authority \|
49
50	Listen-server caveat: the host is both `ROLE_Authority` and locally controlled.
51	Use `IsLocallyControlled()` to distinguish logic that should skip the host player.
52
53	---
54
55	## UNetDriver
56
57	`UNetDriver` is the core transport class responsible for managing all network connections and
58	packet delivery for a world. It owns the list of `UNetConnection` objects and drives the
59	replication tick. Access it via `UWorld::GetNetDriver()`.
60
61	```cpp
62	UNetDriver* Driver = GetWorld()->GetNetDriver();
63	// Driver->ClientConnections — all connected clients (server-side)
64	// Driver->ServerConnection — connection to server (client-side)
65	```
66
67	For most gameplay code you never interact with `UNetDriver` directly; it is relevant when
68	writing custom net drivers, profiling connection state, or debugging packet loss.
69
70	---
71
72	## Property Replication
73
74	### Actor Setup
75
76	```cpp
77	AMyActor::AMyActor()
78	{
79	bReplicates = true; // AActor::SetReplicates() also available at runtime
80	SetReplicateMovement(true); // replicates FRepMovement (location/rotation/velocity)
81	SetNetUpdateFrequency(10.f); // checks per second
82	SetMinNetUpdateFrequency(2.f); // floor when nothing changes
83	NetPriority = 1.0f; // higher = preferred when bandwidth is saturated
84	}
85	```
86
87	From `Actor.h`: `SetReplicates`, `SetReplicateMovement`, `SetNetUpdateFrequency`,
88	`SetMinNetUpdateFrequency`, and `SetNetCullDistanceSquared` are all `ENGINE_API`.
89
90	FRepMovement: when `bReplicateMovement = true`, the engine serializes position,
91	velocity, and rotation into an `FRepMovement` struct (declared in `Actor.h`) and
92	sends it to simulated proxies. `UCharacterMovementComponent` bypasses this with its
93	own prediction-based replication; it writes compressed moves via `FSavedMove_Character`
94	and reconciles them server-side, so `SetReplicateMovement(false)` is the correct
95	default for characters using CMC.
96
97	### Declaring Properties
98
99	```cpp
100	UPROPERTY(Replicated)
101	int32 Health;
102
103	UPROPERTY(ReplicatedUsing = OnRep_State)
104	EMyState State;
105
106	UFUNCTION()
107	void OnRep_State(EMyState PreviousState); // old value passed as optional parameter
108	```
109
110	### GetLifetimeReplicatedProps
111
112	```cpp
113	// MyActor.cpp
114	#include "Net/UnrealNetwork.h"
115
116	void AMyActor::GetLifetimeReplicatedProps(
117	TArray<FLifetimeProperty>& OutLifetimeProps) const
118	{
119	Super::GetLifetimeReplicatedProps(OutLifetimeProps); // NEVER omit this
120	DOREPLIFETIME(AMyActor, Health);
121	DOREPLIFETIME_CONDITION(AMyActor, State, COND_OwnerOnly);
122	DOREPLIFETIME_CONDITION(AMyActor, SimData, COND_SimulatedOnly);
123	DOREPLIFETIME_CONDITION(AMyActor, Ini

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