feat(coding-agent): add get_entries and get_tree RPC commands

Adds two read-only RPC commands exposing existing SessionManager reads:

- get_entries: all session entries in append order, with optional since-entry-id cursor (strictly-after semantics, error on unknown id), plus current leafId.
- get_tree: getTree() roots plus current leafId.

Since sessions are append-only trees with stable entry ids, an entry id is a durable cursor: external orchestrators can use these commands to catch up after a restart without losing pre-compaction history, and can observe branch structure (/tree jumps, abandoned branches) that get_messages hides.

packages/coding-agent/src/index.ts

@@ -224,6 +224,7 @@ export {
 	type SessionInfoEntry,
 	SessionManager,
 	type SessionMessageEntry,
+	type SessionTreeNode,
 	type ThinkingLevelChangeEntry,
 } from "./core/session-manager.ts";
 export {

packages/coding-agent/src/modes/rpc/rpc-client.ts

@@ -10,6 +10,7 @@ import type { ImageContent } from "@earendil-works/pi-ai";
 import type { SessionStats } from "../../core/agent-session.ts";
 import type { BashResult } from "../../core/bash-executor.ts";
 import type { CompactionResult } from "../../core/compaction/index.ts";
+import type { SessionEntry, SessionTreeNode } from "../../core/session-manager.ts";
 import { attachJsonlLineReader, serializeJsonLine } from "./jsonl.ts";
 import type { RpcCommand, RpcResponse, RpcSessionState, RpcSlashCommand } from "./rpc-types.ts";
 
@@ -388,6 +389,22 @@ export class RpcClient {
 		return this.getData<{ messages: Array<{ entryId: string; text: string }> }>(response).messages;
 	}
 
+	/**
+	 * Get session entries in append order, optionally only those after the `since` entry id.
+	 */
+	async getEntries(since?: string): Promise<{ entries: SessionEntry[]; leafId: string | null }> {
+		const response = await this.send({ type: "get_entries", since });
+		return this.getData<{ entries: SessionEntry[]; leafId: string | null }>(response);
+	}
+
+	/**
+	 * Get the session entry tree.
+	 */
+	async getTree(): Promise<{ tree: SessionTreeNode[]; leafId: string | null }> {
+		const response = await this.send({ type: "get_tree" });
+		return this.getData<{ tree: SessionTreeNode[]; leafId: string | null }>(response);
+	}
+
 	/**
 	 * Get text of last assistant message.
 	 */

packages/coding-agent/src/modes/rpc/rpc-mode.ts

@@ -606,6 +606,24 @@ export async function runRpcMode(runtimeHost: AgentSessionRuntime): Promise<neve
 				return success(id, "get_fork_messages", { messages });
 			}
 
+			case "get_entries": {
+				const sessionManager = session.sessionManager;
+				let entries = sessionManager.getEntries();
+				if (command.since !== undefined) {
+					const sinceIndex = entries.findIndex((e) => e.id === command.since);
+					if (sinceIndex === -1) {
+						return error(id, "get_entries", `Entry not found: ${command.since}`);
+					}
+					entries = entries.slice(sinceIndex + 1);
+				}
+				return success(id, "get_entries", { entries, leafId: sessionManager.getLeafId() });
+			}
+
+			case "get_tree": {
+				const sessionManager = session.sessionManager;
+				return success(id, "get_tree", { tree: sessionManager.getTree(), leafId: sessionManager.getLeafId() });
+			}
+
 			case "get_last_assistant_text": {
 				const text = session.getLastAssistantText();
 				return success(id, "get_last_assistant_text", { text });

packages/coding-agent/src/modes/rpc/rpc-types.ts

@@ -10,6 +10,7 @@ import type { ImageContent, Model } from "@earendil-works/pi-ai";
 import type { SessionStats } from "../../core/agent-session.ts";
 import type { BashResult } from "../../core/bash-executor.ts";
 import type { CompactionResult } from "../../core/compaction/index.ts";
+import type { SessionEntry, SessionTreeNode } from "../../core/session-manager.ts";
 import type { SourceInfo } from "../../core/source-info.ts";
 
 // ============================================================================
@@ -59,6 +60,8 @@ export type RpcCommand =
 	| { id?: string; type: "fork"; entryId: string }
 	| { id?: string; type: "clone" }
 	| { id?: string; type: "get_fork_messages" }
+	| { id?: string; type: "get_entries"; since?: string }
+	| { id?: string; type: "get_tree" }
 	| { id?: string; type: "get_last_assistant_text" }
 	| { id?: string; type: "set_session_name"; name: string }
 
@@ -181,6 +184,20 @@ export type RpcResponse =
 			success: true;
 			data: { messages: Array<{ entryId: string; text: string }> };
 	  }
+	| {
+			id?: string;
+			type: "response";
+			command: "get_entries";
+			success: true;
+			data: { entries: SessionEntry[]; leafId: string | null };
+	  }
+	| {
+			id?: string;
+			type: "response";
+			command: "get_tree";
+			success: true;
+			data: { tree: SessionTreeNode[]; leafId: string | null };
+	  }
 	| {
 			id?: string;
 			type: "response";