Add ACP agent backend and terminal controls

crates/acp/src/events.rs

@@ -0,0 +1,103 @@
+use agent_client_protocol::schema::v1::{
+    ContentBlock, Cost, RequestPermissionRequest, SessionId, StopReason, ToolCallId, ToolCallStatus,
+};
+
+use crate::PermissionDecision;
+
+/// Visible events produced while Galaxy drives an ACP turn.
+#[derive(Clone, Debug, PartialEq)]
+#[non_exhaustive]
+pub enum AcpEvent {
+    /// A new or restored ACP session is ready.
+    SessionStarted {
+        /// Agent-owned session identifier.
+        session_id: SessionId,
+        /// Whether this agent advertised `session/load`.
+        can_load: bool,
+        /// Whether this agent advertised the Codex `_session/steering`
+        /// extension.
+        can_steer: bool,
+    },
+    /// A streamed text fragment from the agent.
+    AgentText {
+        /// Markdown-capable text fragment.
+        text: String,
+    },
+    /// A streamed reasoning fragment from the agent.
+    AgentThought {
+        /// Thought text fragment.
+        text: String,
+    },
+    /// A non-text content block from an agent message or thought.
+    AgentContent {
+        /// ACP content block.
+        content: ContentBlock,
+        /// `true` when this block came from an agent-thought update.
+        thought: bool,
+    },
+    /// Content supplied by the user while a prompt is already running.
+    ///
+    /// ACP agents use this update to echo accepted live steering input. Galaxy
+    /// can render it as a user message without exposing hidden system context.
+    UserContent {
+        /// ACP content block accepted by the agent.
+        content: ContentBlock,
+    },
+    /// A tool call began.
+    ToolCall {
+        /// ACP tool-call identifier.
+        id: ToolCallId,
+        /// Human-readable title.
+        title: String,
+        /// Current execution status.
+        status: ToolCallStatus,
+        /// Bounded, control-sequence-free output suitable for Galaxy's tool pane.
+        output: Option<String>,
+    },
+    /// A tool call changed.
+    ToolCallUpdate {
+        /// ACP tool-call identifier.
+        id: ToolCallId,
+        /// New title, when supplied by the agent.
+        title: Option<String>,
+        /// New status, when supplied by the agent.
+        status: Option<ToolCallStatus>,
+        /// Bounded, control-sequence-free output supplied by this update.
+        output: Option<String>,
+    },
+    /// Context-window or cost information changed.
+    Usage {
+        /// Tokens currently in context.
+        used: u64,
+        /// Total context-window size.
+        size: u64,
+        /// Optional cumulative cost.
+        cost: Option<Cost>,
+    },
+    /// The agent asked for permission.
+    PermissionRequested {
+        /// Original request, suitable for rendering in Galaxy.
+        request: RequestPermissionRequest,
+    },
+    /// Galaxy's permission hook resolved a request.
+    PermissionResolved {
+        /// Session to which the permission applies.
+        session_id: SessionId,
+        /// Decision returned by the hook.
+        decision: PermissionDecision,
+    },
+    /// The prompt turn completed.
+    Finished {
+        /// ACP stop reason.
+        stop_reason: StopReason,
+    },
+    /// A recoverable or terminal runtime error for this turn.
+    Error {
+        /// Safe, user-presentable error description.
+        message: String,
+    },
+}
+
+#[cfg(test)]
+#[path = "events_tests.rs"]
+mod tests;