0.5.0 #14

Breaking changes

• acp.helpers.embedded_text_resource and embedded_blob_resource now
  return TextResourceContents / BlobResourceContents rather than the
  wrapper class. Wrap those results with helpers.resource_block(...)
  when emitting embedded resources.

Highlights

• Track upstream agent-client-protocol v0.5.0, including support for
  AvailableCommandsUpdate, CurrentModeUpdate, session mode metadata,
  and raw tool-call rawInput / rawOutput fields across the schema.
• Introduce the experimental acp.contrib package with
  SessionAccumulator for stateful UI aggregation, ToolCallTracker for
  agent-side tool stream management, and PermissionBroker to standardise
  permission prompts. Extensive contrib test coverage ships under tests/ contrib/.
• Extend acp.helpers with update_available_commands,
  update_current_mode, and richer tool-call builders
  (start_read_tool_call, start_edit_tool_call) that populate locations
  and raw payloads automatically.
• Document the contrib surface in the new docs/contrib.md guide and
  surface it in the MkDocs navigation.
• Improve schema generation tooling with additional rename overrides so
  the generated models line up with the Rust/TypeScript SDK naming.