Fantasy Net

Fantasy-net

Fantasy is a high-performance C# distributed game server framework based on ECS architecture, using FTask for async operations.

Core Principles

Fantasy Technical Specifications

• Use FTask for all async operations, not Task
• Separate Entity data from logic (Handler/System); multi-assembly projects must separate to support hot reload
• Name Component business extension classes {ComponentFullName}System; add a static {Domain}Helper only when other systems need a shared business entry point
• All registration is done at compile-time by source generators; don't manually register, don't modify .g.cs
• Entities, components, and Handlers use sealed class; all classes except structs must be created via Entity
• Use file-scoped namespaces (namespace Fantasy;)
• Use Log.Debug/Info/Error() for logging; return error codes via response.ErrorCode; business logic should not throw exceptions
• Use Event system for module decoupling: publish events instead of direct calls; prefer Struct events (zero GC), use Entity events for complex logic; use EventSystem for sync, AsyncEventSystem for async
• Name Event listeners {EventName}_{BusinessAction}, such as OnHpChange_ExitGame; never suffix them with System, Async, or Handler
• When Control Center is enabled, use ServiceDiscovery for dynamic Root Scene and SubScene routing; keep strict account-to-node affinity in business storage rather than the service registry
• Before planned Scene shutdown, call ServiceDiscovery.SetSceneOfflineAsync, reject new business allocations, wait one discovery cache cycle, then drain and close the Scene
• Strictly follow SOLID principles

Development Behavioral Guidelines

Tradeoff: These guidelines bias toward caution over speed. For trivial tasks, use judgment.

See references/guidelines-examples.md for detailed Fantasy scenario examples.

1. Think Before Coding

Don't assume. Don't hide confusion. Surface tradeoffs.

Before implementing:

• State your assumptions explicitly. If uncertain, ask.
• If multiple interpretations exist, present them - don't pick silently.
• If a simpler approach exists, say so. Push back when warranted.
• If something is unclear, stop. Name what's confusing. Ask.

Fantasy Key Points: Before implementing, clarify: architecture pattern (single-server/distributed), Entity ownership (which Scene), communication method (Roaming/Address/SphereEvent), configuration source (local Fantasy.config or Control Center), and whether dynamic discovery or strict persistent affinity is required. When uncertain, ask; don't assume.

2. Simplicity First

Minimum code that solves the problem. Nothing speculative.

• No features beyond what was asked.
• No abstractions for single-use code.
• No "flexibility" or "configurability" that wasn't requested.
• No error handling for impossible scenarios.
• If you write 200 lines and it could be 50, rewrite it.

Ask yourself: "Would a senior engineer say this is overcomplicated?" If yes, simplify.

Fantasy Key Points: Avoid premature abstraction of Entity/Component structures; don't design factory/strategy patterns for single scenarios. When users only need basic functionality, write Component + necessary AwakeSystem directly; refactor when extension is needed.

3. Surgical Changes

Touch only what you must. Clean up only your own mess.

When editing existing code:

• Don't "improve" adjacent code, comments, or formatting.
• Don't refactor things that aren't broken.
• Match existing style, even if you'd do it differently.
• If you notice unrelated dead code, mention it - don't delete it.

When your changes create orphans:

• Remove imports/variables/functions that YOUR changes made unused.
• Don't remove pre-existing dead code unless asked.

The test: Every changed line should trace directly to the user's request.

Fantasy Key Points: Never modify .g.cs generated files (if you find issues, modify source files and regenerate). Don't manually adjust source generator registration code. Don't "optimize" existing Entity/Component structures unless user explicitly requests refactoring.

4. Goal-Driven Execution

Define success criteria. Loop until verified.

Transform tasks into verifiable goals:

• "Add validation" → "Write tests for invalid inputs, then make them pass"
• "Fix the bug" → "Write a test that reproduces it, then make it pass"
• "Refactor X" → "Ensure tests pass before and after"

For multi-step tasks, state a brief plan:

1. [Step] → verify: [check]
2. [Step] → verify: [check]
3. [Step] → verify: [check]

Strong success criteria let you loop independently. Weak criteria ("make it work") require constant clarification.

Fantasy Key Points: Define verifiable steps and criteria: protocol export (dotnet fantasy-export successfully generates .g.cs), compilation passes (dotnet build with no errors), Handler registration (check generated registration code), message flow (Log.Debug outputs key nodes, confirm request/response correctness).

Reference File Navigation

Read the corresponding file based on the requirement; for complex tasks, read multiple files.