fix(acp)!: preserve JSON-RPC frames across transport adapters

[benbrandt]

Carry complete single, batch, and malformed frames through component, tracing, HTTP, WebSocket, and polyfill boundaries. Preserve grouped responses and HTTP request provenance, including duplicate and null IDs.

BREAKING CHANGE: Channel now carries TransportFrame instead of Result<RawJsonRpcMessage, Error>. FramedChannel and into_framed_channel_and_future are removed.

[Copilot]

Pull request overview

This PR updates the ACP Rust SDK’s in-process transport boundary so protocol components and transport adapters preserve complete JSON-RPC frames (single values, non-empty batches, and malformed wire input) end-to-end. It removes the legacy Result<RawJsonRpcMessage, Error>-based channel API in favor of a frame-aware Channel<TransportFrame>, and updates core routing plus HTTP/WebSocket/polyfill integrations to maintain batch grouping, request provenance, and duplicate/null ID behavior.

Changes:

• Make Channel carry TransportFrame (single/batch/malformed) and remove FramedChannel / into_framed_channel_and_future.
• Introduce public TransportBatch / TransportBatchEntry and add TransportFrame::{parse_json,to_json} utilities to round-trip frames across text-based transports.
• Update HTTP + WebSocket servers/clients and the MCP-over-ACP polyfill to preserve batch frames and correctly correlate grouped responses.

Reviewed changes

Copilot reviewed 24 out of 24 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/agent-client-protocol/tests/protocol_v2.rs	Updates protocol v2 tests to send/receive TransportFrame::Single on channels.
src/agent-client-protocol/tests/jsonrpc_transport_close.rs	Adjusts close/drain tests for the new frame-based channel semantics.
src/agent-client-protocol/tests/jsonrpc_batch.rs	Updates documentation to reflect batch-aware frames at the channel boundary.
src/agent-client-protocol/src/stdio.rs	Switches stdio transport adapter to into_channel_and_future returning Channel.
src/agent-client-protocol/src/role/acp.rs	Migrates ACP role/router wiring to frame-based channels and malformed handling.
src/agent-client-protocol/src/lib.rs	Publicly re-exports TransportFrame / batch types; removes hidden FramedChannel export.
src/agent-client-protocol/src/jsonrpc/transport_actor.rs	Implements frame parsing/serialization and safe relaying of malformed multiline payloads.
src/agent-client-protocol/src/jsonrpc/outgoing_actor.rs	Updates protocol→transport forwarding to send TransportFrame::Single directly.
src/agent-client-protocol/src/jsonrpc/incoming_actor.rs	Updates frame entry extraction and response-destination assignment for new frame types.
src/agent-client-protocol/src/jsonrpc.rs	Makes TransportFrame/batch types public, removes legacy bridging, and redefines Channel as frame boundary.
src/agent-client-protocol/src/component.rs	Removes into_framed_channel_and_future and legacy negotiation adapter.
src/agent-client-protocol/src/acp_agent.rs	Updates AcpAgent to expose Channel via into_channel_and_future and use TransportFrame.
src/agent-client-protocol/CHANGELOG.md	Documents the breaking channel change and frame-preservation fixes with migration-guide link.
src/agent-client-protocol-polyfill/src/mcp_over_acp/http.rs	Preserves batch frames through MCP-over-ACP HTTP bridge; correlates malformed POST errors to the originating request.
src/agent-client-protocol-polyfill/CHANGELOG.md	Notes batch-frame preservation and malformed correlation fixes in polyfill changelog.
src/agent-client-protocol-http/src/websocket_server.rs	Switches WS handling to TransportFrame::parse_json, forwards batches intact, and adds grouped-response tests.
src/agent-client-protocol-http/src/http_server.rs	Adds batch-aware POST handling and session-aware routing while preserving grouped batch responses.
src/agent-client-protocol-http/src/connection.rs	Routes outbound frames (single/batch/malformed), supports duplicate IDs via queued pending routes, and adds tests.
src/agent-client-protocol-http/src/client.rs	Updates HTTP client transport to post/receive frames (including batches/malformed) and adds end-to-end preservation tests.
src/agent-client-protocol-http/CHANGELOG.md	Notes batch-frame preservation fixes for HTTP and WebSocket transports.
src/agent-client-protocol-conductor/src/snoop.rs	Updates conductor snooper to bridge with inspection using Channel instead of FramedChannel.
md/transport-architecture.md	Updates architecture doc to describe TransportFrame boundary and frame-based Channel.
md/SUMMARY.md	Adds the v2.0 migration guide to the mdBook ToC.
md/migration_v2.0.md	Adds a 2.0 migration guide describing the new Channel<TransportFrame> boundary and removed APIs.