plugin-architecture

name	plugin-architecture
description	Use when creating, refactoring, or reviewing axios-retryer plugins. Enforces the repo's single recommended plugin architecture: top-level orchestrator class, focused folders for types/configs/errors/utils, optional stateful managers or storage adapters, explicit event-driven boundaries, and test-first extraction when files grow.

Plugin Architecture

Use this skill for any new plugin, major plugin refactor, or review of plugin structure in axios-retryer.

Goal

Follow one consistent plugin shape across the repo:

src/plugins/YourPlugin/
  YourPlugin.ts
  index.ts
  types/
    index.ts
  configs/
    index.ts
  errors/
    YourPluginError.ts
    index.ts
  utils/
    *.ts
    index.ts
  managers/
    *.ts
  storage/
    *.ts
  interceptors/
    RequestInterceptor.ts
    ResponseInterceptor.ts
    ErrorInterceptor.ts

Only keep folders that the plugin actually needs. Do not create placeholder folders.

Current Plugin Contract

Read src/types/plugins.ts before writing plugin code. The current public plugin contract is:

• RetryPlugin<TPluginEvents> requires name, version, initialize(context), and optional onBeforeDestroyed(context).
• Plugins should declare readonly _events?: Readonly<TPluginEvents> for TypeScript event inference.
• initialize receives PluginContext<TPluginEvents>, which is the only supported bridge into manager behavior.

Current PluginContext surface

• axiosInstance
• getLogger()
• on(...)
• off(...)
• emit(...)
• triggerAndEmit(...)
• cancelRequest(requestId)
• cancelAllRequests()
• cancelQueuedRequests()
• registerQueueGate(name, canProcess)
• unregisterQueueGate(name)
• refreshQueue()
• registerMetricsRecorder(recorder | null)
• getTimerStats()
• releaseRequestTracking(config)

Use these methods as they exist today. Do not invent new plugin-manager touchpoints when the current context already supports the behavior.

Architecture Rules

1. YourPlugin.ts is the orchestrator only. Keep initialize, teardown, interceptor registration, event wiring, and public methods here. If the file starts accumulating parsing, normalization, validation, sorting, mutation, or adapter logic, extract it.

2. index.ts is public API only. Export the plugin class, factory, public types, and public errors. Do not place logic in the entrypoint.

3. types/ owns contracts. Plugin options, events, adapter interfaces, storage entries, and request metadata types live here. Public types are additive only unless the user explicitly wants a breaking change.

4. configs/ owns defaults and validation. Resolve defaults in one place. Throw config errors there, not deep inside request flow.

5. errors/ owns plugin-specific error classes. Every custom error gets its own file when there is more than one.

6. utils/ is pure logic only. Put stateless helpers here: key building, normalization, cloning, matching, fingerprints, payload shaping. No hidden shared mutable state.

7. managers/ or storage/ own plugin-local state. If the plugin needs durable or cross-request state, isolate it behind a named boundary with a narrow interface. Do not hide stateful behavior inside generic utils.

8. interceptors/ split lifecycle phases when complexity grows. If a plugin has meaningful request/response/error logic, move each phase into dedicated files instead of keeping them inline.

Behavioral Rules

• Plugins are self-sufficient and event-driven.
• The core should not call plugin business methods directly.
• Prefer emitting plugin events through context.triggerAndEmit(...) at the outer boundary.
• Use context.emit(...) only when you explicitly need listener notification without hook execution.
• Queue-blocking plugins should use registerQueueGate(...) and refreshQueue() instead of ad hoc shared state in the core.
• Metrics-producing plugins should integrate through registerMetricsRecorder(...) instead of direct manager mutation.
• Keep side effects near the boundary and keep internal helpers deterministic.
• Never use any.
• Add explicit return types on extracted functions.
• If a file crosses roughly 200 lines, extract a focused collaborator.

Implementation Workflow

1. Read the plugin contract in src/types/plugins.ts.
2. Inspect at least one existing plugin before creating a new one.
3. Map the plugin behavior onto the existing PluginContext methods before adding code.
4. Define public plugin events and options in types/.
5. Add config defaults and validation in configs/.
6. Put orchestration in YourPlugin.ts.
7. Extract pure helper logic into utils/.
8. Extract stateful collaborators into managers/, storage/, or interceptors/ if needed.
9. Export only the intended public surface from index.ts.
10. Add or update focused unit tests alongside the implementation.
11. If the plugin changes public behavior, update website docs.

Read Before Coding

• For concrete folder layout and extraction thresholds, read references/folder-structure.md.

Load only that reference when you are actively designing or restructuring a plugin.