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acp_dart

0.5.02.9K downloads/moSkrOYC/acp-dart ↗New releases in your daily digest, changelog included.

A Dart implementation of the Agent-Client Protocol (ACP) for building AI-powered applications.

Last release 14 days ago
24 Sep 2026
Ships fairly regularly
a new release about every 5 months
Nearly every release is documented
notes for 5 of 5 stable releases
Nothing withdrawn
no release was ever pulled
12 months old
5 releases · first in 2025

Release timeline

5 releases since 2025

20252026

One column per month.

Releases

0.5.024 Sept 2026
Remote JSON-RPC errors now complete request futures with RequestError instead of a raw JSON map. Catch RequestError and read its code, message, and da
Breaking changes

Remote JSON-RPC errors now complete request futures with RequestError instead of a raw JSON map. Catch RequestError and read its code, message, and data fields.

cancelPendingRequest no longer rejects the pending request locally. It sends $/cancel_request, and the original request future stays pending until the peer replies or the connection closes. Use sendRequestWithCancellation when you have a cancellation future for a specific request.

Configuration values now support both select strings and booleans. Check an option's type before reading currentValue; create boolean options with type: 'boolean', a boolean value, and no select options. Tool-call rawInput and rawOutput can also contain any JSON value, so narrow them before treating them as maps.

ndJsonStream now sends JSON-RPC parse or invalid-request errors for malformed nonempty input instead of silently dropping it.

Added

Track the ACP v1 method inventory from the official TypeScript SDK v1.5.0, including stable session lifecycle and elicitation methods and explicitly experimental provider, NES, document, MCP, plan, and compaction payloads.

Provide app-style agent() and client() handler registration, connection contexts, session builders, session update queues, and request-scoped cancellation.

Add HTTP with SSE and WebSocket client transports, an HTTP and WebSocket server adapter, and an in-memory affinity cookie store for Dart VM integrations.

Add pinned upstream JSON fixtures, connected byte-stream tests, process and HTTP/WebSocket loopback tests, and an opt-in TypeScript-to-Dart interoperability test.

Stress test real peers with Dart client to TypeScript server over HTTP/SSE and TypeScript client to Dart server over HTTP/SSE and WebSocket, including concurrent sessions, callbacks, errors, cancellation, and reconnects.

Changed

Reject pending requests when connections close and expose cooperative request-scoped cancellation to handlers.

Decode boolean configuration options, resource content blocks, grouped options, terminal authentication fields, and every v1.5 session update discriminator through the public schema API.

Keep unstableListSessions and unstableResumeSession as compatibility aliases while exposing stable listSessions and resumeSession methods.

Replace README examples that used invalid Dart model fields with verified source examples and a v1.5 method matrix.

Compatibility

ACP v2 is outside this package's scope. The TypeScript SDK v1.5.0 marks provider, NES, document, MCP-over-ACP, plan, and compaction surfaces as experimental.

session/set_model remains a Dart legacy extension and is absent from the TypeScript SDK v1.5.0 agent method inventory.

HTTP, SSE, and WebSocket adapters in this release use dart:io and do not run in a browser.

The WebSocket client can send stored affinity cookies, but it cannot store a cookie from an upgrade response because dart:io does not expose those headers.

0.4.06 Mar 2026

Stable Method Support: Added end-to-end support for session/set_config_option with typed request/response models and connection dispatch wiring.

Added

Stable Method Support: Added end-to-end support for session/set_config_option with typed request/response models and connection dispatch wiring.
Unstable Session Surface: Added unstable support for session/list, session/fork, and session/resume, including typed schema models, capability models, and client/agent interface wiring.
Protocol Cancellation: Added protocol-level $/cancel_request support with typed notifications and connection helpers to cancel pending outbound requests.
Schema/Model Coverage: Expanded schema parity with session config option selector families, session capability objects, additional session update variants, and usage/cost payload models.
Typed Unions Expansion: Extended request/response/notification union coverage to include newly supported session and protocol methods.
Maintainer Parity Process: Added parity_verification_checklist.md for release-time parity verification.

Changed

Extension Method Semantics: extMethod and extNotification now preserve method names exactly as provided; callers must include protocol extension prefixes (for example, leading _) explicitly.
Request Error Mapping: Validation-like failures now map to JSON-RPC -32602 (Invalid params) and unexpected runtime failures map to sanitized -32603 (Internal error) payloads.
NDJSON Stream Robustness: ndJsonStream now skips malformed non-empty lines and continues processing valid messages, with optional onParseError diagnostics.
Documentation Accuracy: README now uses an explicit stable/unstable/unsupported support matrix instead of broad completeness claims.
Release Notes Accuracy: Corrected prior filesystem wording to avoid implying unsupported non-stable filesystem method families.

Developer Experience

Reproducible Environment: Added devenv configuration (devenv.nix, devenv.yaml, devenv.lock) for consistent local setup and CI-like workflows.
Regression Test Coverage: Expanded ACP dispatch, schema round-trip, union mapping, extension, cancellation, and stream error-path test coverage.

Compatibility Notes

Potentially Breaking: Extension method name auto-prefixing behavior was removed; integrations relying on implicit _ rewriting must update call sites.
Behavioral Change: Malformed NDJSON lines no longer fail the stream by default; they are dropped unless handled through onParseError.
Behavioral Change: Some failures previously surfaced as generic internal errors now return Invalid params when they are parameter/validation related.

Open source →

0.3.017 Oct 2025

Protocol Parity: Rebuilt every data model to match the official ACP schema.json, including sessions, permissions, plans, content payloads, terminal up

Protocol Parity: Rebuilt every data model to match the official ACP schema.json, including sessions, permissions, plans, content payloads, terminal updates, MCP server descriptors, and _meta envelopes; regenerated schema.g.dart to keep serialization in lock-step.
Client Operations Coverage: Implemented ACP client request/response models for read/write text-file and terminal workflows, ensuring each request carries the appropriate sessionId, path fields, and limits, and aligned WaitForTerminalExit and related responses with nullable exit metadata.
Typed RPC Unions: Introduced sealed Agent/Client request, response, and notification unions with exhaustive handling and constant tables; added comprehensive round-trip tests plus HTTP and SSE example flows that exercise the new types end-to-end.
Converters & Utilities: Harmonized converters for session updates, MCP servers, permission requests, and tool-call content, removing non-spec variants while preserving forward-compatible Unknown* fallbacks.
Stability Fixes: Corrected numerous spec mismatches (capability flags, optionality, naming, prompt payloads) and tightened serialization behaviors to prevent regressions.
Docs & Testing: Updated research notes, tracked schema alignment in schema_alignment_checklist.md, refreshed examples, and broadened test coverage to guard the new behavior.

Open source →

acp_dart

Release timeline

Releases

Breaking changes

Added

Changed

Compatibility

Added

Changed

Developer Experience

Compatibility Notes