#1259 feat: add Valkey-backed TaskStore and ResumableStreamStore

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://voltagent.dev/docs/community/contributing/#commit-convention

Bugs / Features

• Related issue(s) linked https://github.com/VoltAgent/voltagent/issues/1258
• Tests for the changes have been added
• Docs have been added / updated
• Changesets have been added https://voltagent.dev/docs/community/contributing/#creating-a-changeset

What is the current behavior?

The @voltagent/a2a-server and @voltagent/resumable-streams packages only support in-memory storage. Task state and stream data are lost on restart and cannot be shared across multiple server instances.

What is the new behavior?

Adds Valkey-backed store implementations to both packages using the @valkey/valkey-glide client library:

@voltagent/a2a-server

• New ValkeyTaskStore class implementing the TaskStore interface with composite key generation, JSON serialization, and optional TTL-based expiration.
• createValkeyTaskStore factory function for easy instantiation.
• New taskStore option on A2AServerConfig so a store can be provided at construction time.

@voltagent/resumable-streams

• New createResumableStreamValkeyStore factory that wires Valkey pub/sub into the resumable-stream generic context, with per-channel dedicated GlideClient connections and a configurable max subscription limit (default 1000).
• TTL support for active stream keys via optional ttlSeconds.
• Exports internal utilities (markResumableStreamStoreType, buildActiveStreamKey, createActiveStreamStoreFromPublisher, mergeStreamAndActiveStore) for reuse by custom store implementations.

Shared

• @valkey/valkey-glide added as an optional peer dependency in both packages so consumers who don't use Valkey are unaffected.
• Both stores support standalone and cluster Valkey deployments, configurable key prefixes, and optional TTL.

Example

• New examples/with-valkey-store project demonstrating end-to-end integration of both stores with a SupportAgent, including environment config template and README.

Tests

• Comprehensive unit tests for ValkeyTaskStore (load, save, error handling, cancellations, factory function).
• Comprehensive unit tests for createResumableStreamValkeyStore (publisher/subscriber adapters, TTL, subscription limits, close cleanup).

Notes for reviewers

• The @valkey/valkey-glide peer dependency is optional, no impact on existing consumers.
• The resumable-streams Valkey store creates one dedicated GlideClient per subscription channel, which is a requirement of the Glide pub/sub model. The maxSubscriptions option (default 1000) caps resource usage.

Summary by CodeRabbit

• New Features
  • Added Valkey-backed persistence for A2A tasks and resumable streams, with configurable key prefixes and optional expiration. Supports standalone and cluster deployments.
  • Added a Valkey store example with a sample assistant and setup instructions.
• Bug Fixes
  • Agent failures are now recorded in task history and reflected in the task’s failed status.
  • Invalid message content is rejected during request validation.
• Breaking Changes
  • Server configuration can now specify a task store, taking precedence over an injected store or the in-memory fallback.
• Tests
  • Added coverage for Valkey task and resumable-stream storage.