refactor: move event system to reducer, remove engine package #32

2026-01-16T23:51:05Z

mvhutz commented

2026-01-16 23:51:05 +00:00

Description

This PR completes the MVC-inspired refactoring by moving the event system from the engine into the reducer.
The engine package is now removed entirely, as the reducer handles both reduction logic and lifecycle events.

Add pkg/reducer/events.go with StartEvent, StepEvent, and StopEvent.
Extend Reducer interface to embed Emitter[Event] and add Expression() method.
Update NormalOrderReducer to embed BaseEmitter and emit lifecycle events during reduction.
Update all plugins to attach to Reducer instead of Engine.
Remove internal/engine package entirely.
Add Off() method to BaseEmitter to complete the Emitter interface.
Fix Emitter.On signature to use generic type E instead of string.

Decisions

The Reducer interface now combines reduction logic with event emission, making it the single orchestration point.
Plugins attach directly to the reducer, simplifying the architecture.
The Expression() method on Reducer provides access to current state for plugins.

Benefits

Simpler architecture with one fewer abstraction layer.
Plugins are now mode-agnostic - they work with any Reducer implementation.
Cleaner separation: reducers handle reduction, plugins observe via events.
Easier to add new evaluation modes - just implement Reducer with embedded emitter.

Checklist

Code follows conventional commit format.
Branch follows naming convention (<type>/<description>).
Tests pass (if applicable).
Documentation updated (if applicable).

## Description This PR completes the MVC-inspired refactoring by moving the event system from the engine into the reducer. The engine package is now removed entirely, as the reducer handles both reduction logic and lifecycle events. - Add `pkg/reducer/events.go` with `StartEvent`, `StepEvent`, and `StopEvent`. - Extend `Reducer` interface to embed `Emitter[Event]` and add `Expression()` method. - Update `NormalOrderReducer` to embed `BaseEmitter` and emit lifecycle events during reduction. - Update all plugins to attach to `Reducer` instead of `Engine`. - Remove `internal/engine` package entirely. - Add `Off()` method to `BaseEmitter` to complete the `Emitter` interface. - Fix `Emitter.On` signature to use generic type `E` instead of `string`. ### Decisions - The `Reducer` interface now combines reduction logic with event emission, making it the single orchestration point. - Plugins attach directly to the reducer, simplifying the architecture. - The `Expression()` method on `Reducer` provides access to current state for plugins. ## Benefits - Simpler architecture with one fewer abstraction layer. - Plugins are now mode-agnostic - they work with any `Reducer` implementation. - Cleaner separation: reducers handle reduction, plugins observe via events. - Easier to add new evaluation modes - just implement `Reducer` with embedded emitter. ## Checklist - [x] Code follows conventional commit format. - [x] Branch follows naming convention (`<type>/<description>`). - [x] Tests pass (if applicable). - [ ] Documentation updated (if applicable).

mvhutz added 1 commit 2026-01-16 23:51:05 +00:00

refactor: move event system to reducer, remove engine package bcc0331149

Move the event emitter and lifecycle events from the engine into the reducer,
making the reducer the single point of orchestration for reduction.
This eliminates the engine package entirely.

- Add events.go to pkg/reducer with Start, Step, and Stop events.
- Extend Reducer interface to embed Emitter and add Expression() method.
- Update NormalOrderReducer to embed BaseEmitter and emit lifecycle events.
- Update all plugins to attach to Reducer instead of Engine.
- Remove internal/engine package.
- Add Off() method to BaseEmitter to complete Emitter interface.
- Fix Emitter.On signature to use generic type E instead of string.

mvhutz added 1 commit 2026-01-16 23:56:05 +00:00

fix: update main and tests for new Reducer API aeffe64804

Update call sites to match the new Reducer interface where the expression
is passed to the constructor and Reduce() takes no arguments.

mvhutz added 1 commit 2026-01-16 23:58:11 +00:00

docs: add tea pr edit instructions to CLAUDE.md b69898cf39

mvhutz added 1 commit 2026-01-17 00:02:30 +00:00

docs: replace tea pr edit with tea comment in CLAUDE.md 475d79c334

The tea CLI does not have a pr edit command.
Updated documentation to use tea comment instead.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

mvhutz added 1 commit 2026-01-17 00:03:17 +00:00

docs: add guidance for commenting on PR updates cb4f42c91d

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

mvhutz added 1 commit 2026-01-17 00:09:26 +00:00

style: moved isViable to reducer d9639ecc2b

mvhutz added 1 commit 2026-01-17 00:27:16 +00:00

feat: stuff 8dc5d986fd

mvhutz merged commit 1974ad582f into main

2026-01-17 00:27:37 +00:00

mvhutz deleted branch refactor/move-events-to-reducer

2026-01-17 00:27:37 +00:00

mvhutz referenced this issue from a commit

2026-01-17 00:27:37 +00:00

refactor: move event system to reducer, remove engine package (#32)

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Reference: mvhutz/lambda#32