RUDPClient/openspec/specs/shared-network-foundation/spec.md

shared-network-foundation Specification

Purpose

Define the shared transport, session-lifecycle, and message-routing foundation that both client and server hosts use without depending on Unity-specific runtime host classes.

Requirements

Requirement: Shared network core is host-agnostic

The project SHALL provide a shared network core that contains transport, session, envelope parsing, and message-routing behavior without depending on Unity-specific runtime host classes such as MonoBehaviour or frame-loop callbacks. Both client and server networking hosts MUST be able to use this shared core.

Scenario: Client host uses shared network core

• WHEN the Unity client constructs its runtime networking stack
• THEN it uses the shared transport and message-routing core for transport startup, sending, receiving, and handler registration
• THEN Unity-specific logic remains in the client host adapter rather than in the shared core classes

Scenario: Server host can use the same core without Unity types

• WHEN a server-side host constructs the runtime networking stack
• THEN it can use the same shared transport and message-routing core without depending on Unity host classes
• THEN server-specific startup and lifetime control are provided by a separate host adapter

Requirement: Message routing uses a host-provided dispatcher strategy

The shared message-routing layer SHALL execute received business handlers through a host-provided dispatcher abstraction rather than constructing a Unity-specific dispatcher internally. The host MUST be able to choose the dispatch strategy that matches its runtime model.

Scenario: Unity client injects a queued main-thread dispatcher

• WHEN the Unity client constructs the shared message-routing layer
• THEN it supplies a dispatcher implementation that queues work for later execution on the Unity main thread
• THEN received handlers run according to that injected client dispatch strategy

Scenario: Server host injects a non-Unity dispatch strategy

• WHEN a non-Unity server host constructs the shared message-routing layer
• THEN it supplies a dispatcher implementation that does not rely on Unity frame-loop semantics
• THEN the shared message-routing layer still processes received messages correctly through that host-selected strategy

Requirement: Shared core preserves current transport and message contracts

The shared client/server foundation SHALL preserve the envelope-based business-message contract across client and server hosts while allowing delivery-policy selection behind the shared message-routing layer. Reliable control traffic MUST continue to use the existing ITransport contract, and high-frequency sync traffic MUST be composable through a host-agnostic sync strategy without introducing Unity-specific runtime types into the shared networking core.

Scenario: Shared hosts exchange the same envelope format across delivery lanes

• WHEN a client host sends a business message through either the reliable control path or the high-frequency sync path
• THEN the payload is encoded with the same shared envelope and message-type contract
• THEN the server host decodes and routes it through shared networking logic without a host-specific protocol fork

Scenario: Hosts compose delivery-policy selection without Unity dependencies

• WHEN a non-Unity server host constructs the runtime networking stack with reliable control traffic and a high-frequency sync lane
• THEN it uses shared delivery-policy abstractions without depending on Unity frame-loop types
• THEN the Unity client can use the same abstractions while still supplying its own host-specific dispatch behavior

Requirement: Shared runtime owns host-agnostic session lifecycle orchestration

The shared network foundation SHALL include host-agnostic session lifecycle orchestration alongside transport startup and message routing. Client and server hosts MUST be able to compose the shared foundation with session orchestration that consumes transport events, login results, and heartbeat signals without depending on Unity-specific runtime types, while supporting both single-session client composition and multi-session server composition.

Scenario: Client host composes runtime with single-session lifecycle manager

• WHEN the Unity client constructs its shared networking runtime
• THEN that runtime includes shared session lifecycle management for its single remote session in addition to transport and message routing
• THEN Unity-specific code remains responsible only for reacting to lifecycle state changes and driving host behavior

Scenario: Server host composes shared foundation with multi-session orchestration

• WHEN a non-Unity server host constructs the runtime networking stack for multiple remote peers
• THEN it uses the shared transport and message-routing foundation together with shared multi-session lifecycle orchestration
• THEN server-specific cleanup, admission, and gameplay reactions stay in the server host adapter rather than forking the shared lifecycle contract