glm-5.1
04b3464c36
New sub-path export @alkdev/pubsub/call providing:
- CallEventSchema (TypeBox schemas) for call.requested/responded/part/completed/aborted/error
- PendingRequestMap with call() (request/response) and subscribe() (streaming via Repeater)
- CallError class and CallErrorCode constants
- Scoped topic subscriptions (call.responded:{requestId}) to avoid O(n) fanout
- subscribe() yields call.part events until call.completed or call.error,
with automatic call.aborted on consumer break
Also adds @alkdev/typebox as runtime dependency and architecture doc.
96 lines
5.2 KiB
Markdown
96 lines
5.2 KiB
Markdown
---
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status: draft
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last_updated: 2026-04-30
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---
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# @alkdev/pubsub Architecture
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Type-safe publish/subscribe with pluggable event target adapters. The core (`createPubSub` + `TypedEventTarget` + operators) has no transport dependency. Each adapter (Redis, WebSocket, Iroh) is an isolated module that only imports its own peer dependency.
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## Why This Exists
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Extracted from `@alkdev/alkhub_ts/packages/core/pubsub/`, which itself was adapted from `@graphql-yoga/subscription` and `@graphql-yoga/typed-event-target`. The pubsub module was already self-contained within alkhub — zero cross-module imports from operations, config, logger, or MCP. Extracting it into a standalone package:
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1. **Reduces coupling** — alkhub depends on pubsub, not the other way around
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2. **Enables reuse** — multiple alkhub packages can share the same pubsub instance
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3. **Isolates peer deps** — Redis and Iroh are heavy native dependencies; consumers that don't need them shouldn't carry them
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4. **Matches established pattern** — `@alkdev/taskgraph` and `@alkdev/typemap` already use the standalone-package pattern
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## Core Principle
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**The TypedEventTarget interface is the contract.** All transports implement the same `addEventListener` / `dispatchEvent` / `removeEventListener` surface. `createPubSub` doesn't know or care which transport is in use — it just dispatches events to whatever `TypedEventTarget` it was given.
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This means swapping from in-process to Redis to WebSocket to Iroh is a one-line config change:
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```ts
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const pubsub = createPubSub<MyEventMap>({
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eventTarget: createRedisEventTarget({ publishClient, subscribeClient }),
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});
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```
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## What This Package Provides
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- **Core** — `createPubSub`, `TypedEventTarget`, `TypedEvent`, topic scoping, `filter`/`map`/`pipe` operators, `Repeater` (inlined from @repeaterjs/repeater)
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- **Call protocol** (`@alkdev/pubsub/call`) — `PendingRequestMap`, `CallEventSchema`, `CallError`, event types for request/response and streaming operations
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- **Adapters** (each is a peer-dep island, importable via sub-path export):
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- In-process (default `EventTarget`, no adapter needed)
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- Redis (`@alkdev/pubsub/event-target-redis`, peer dep: `ioredis`)
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- WebSocket (future: `@alkdev/pubsub/event-target-websocket`)
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- Iroh (future: `@alkdev/pubsub/event-target-iroh`, peer dep: `@rayhanadev/iroh`)
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## Consumer Context
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### alkhub (hub-spoke coordinator)
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The hub uses pubsub for event routing between operations, runners, and the SSE interface. The event map is the call protocol — typed JSON events (`call.requested`, `call.responded`, `session.status`, etc.). Transport choice depends on deployment:
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| Deployment | Transport |
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|------------|-----------|
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| Single-process hub | In-process (default) |
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| Hub + worker processes | Redis |
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| Hub + remote spokes | WebSocket or Iroh |
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### Future: standalone spoke SDK
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Spokes will import `@alkdev/pubsub` directly to create their event target (WebSocket or Iroh) and wire it into `createPubSub`. Call protocol types and `PendingRequestMap` are available from `@alkdev/pubsub/call`.
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## Threat Model
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- **Fork provenance** — core pubsub and typed event target are adapted from graphql-yoga (MIT). All original copyright notices are preserved in file headers. See [ADR-001](decisions/001-graphql-yoga-fork.md).
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- **Peer dep isolation** — Redis and Iroh are optional peer dependencies. A consumer that only needs in-process transport installs zero extra packages. A consumer using Redis but not Iroh installs `ioredis` only.
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- **Type-only imports** — `event-target-redis.ts` imports `ioredis` types only at compile time. At runtime, the consumer must provide the actual `Redis`/`Cluster` instances.
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## Architecture Documents
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| Document | Content |
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|----------|---------|
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| [api-surface.md](api-surface.md) | createPubSub factory, PubSub types, operators, TypedEventTarget types |
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| [call-protocol.md](call-protocol.md) | Call/subscribe protocol — event types, PendingRequestMap, streaming, error model, transport mapping |
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| [event-targets.md](event-targets.md) | In-process, Redis, WebSocket adapters — interface, configuration, limitations |
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| [iroh-transport.md](iroh-transport.md) | Iroh P2P QUIC transport — protocol, framing, identity, hub/spoke sides, reconnection |
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| [build-distribution.md](build-distribution.md) | Dependencies, project structure, tree-shaking, sub-path exports, targets |
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## Document Lifecycle
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Architecture documents use YAML frontmatter with `status` and `last_updated` fields:
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```yaml
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---
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status: draft | stable | deprecated
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last_updated: YYYY-MM-DD
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---
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```
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| Status | Meaning | Transitions |
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|--------|---------|-------------|
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| `draft` | Under active development. Content may change. | → `stable` when implementation is complete and tests verify API contract. |
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| `stable` | API contracts are locked. Changes require review cycle. | → `deprecated` when superseded. |
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| `deprecated` | Superseded. Kept for reference. | Removed when no longer referenced. |
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## References
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- Source: `@alkdev/alkhub_ts/packages/core/pubsub/`
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- Upstream: `@graphql-yoga/subscription` and `@graphql-yoga/typed-event-target` (MIT)
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- alkhub pubsub-redis doc: `@alkdev/alkhub_ts/docs/architecture/pubsub-redis.md`
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- alkhub spoke-runner doc: `@alkdev/alkhub_ts/docs/architecture/spoke-runner.md`
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- Migration research: `docs/research/migration.md` |