Update rpc.md to match actual implementation

- AppMessage -> AgentMessage
- compact response shows full CompactionResult fields
- auto_compaction_start includes reason field
- auto_compaction_end includes willRetry field
- Fix source file references

packages/coding-agent/docs/rpc.md

@@ -145,7 +145,7 @@ Response:
 }
 ```
 
-Messages are `AppMessage` objects (see [Message Types](#message-types)).
+Messages are `AgentMessage` objects (see [Message Types](#message-types)).
 
 ### Model
 
@@ -289,8 +289,10 @@ Response:
   "command": "compact",
   "success": true,
   "data": {
+    "summary": "Summary of conversation...",
+    "firstKeptEntryId": "abc123",
     "tokensBefore": 150000,
-    "summary": "Summary of conversation..."
+    "details": {}
   }
 }
 ```
@@ -618,7 +620,7 @@ A turn consists of one assistant response plus any resulting tool calls and resu
 
 ### message_start / message_end
 
-Emitted when a message begins and completes. The `message` field contains an `AppMessage`.
+Emitted when a message begins and completes. The `message` field contains an `AgentMessage`.
 
 ```json
 {"type": "message_start", "message": {...}}
@@ -717,20 +719,27 @@ Use `toolCallId` to correlate events. The `partialResult` in `tool_execution_upd
 Emitted when automatic compaction runs (when context is nearly full).
 
 ```json
-{"type": "auto_compaction_start"}
+{"type": "auto_compaction_start", "reason": "threshold"}
 ```
 
+The `reason` field is `"threshold"` (context getting large) or `"overflow"` (context exceeded limit).
+
 ```json
 {
   "type": "auto_compaction_end",
   "result": {
+    "summary": "Summary of conversation...",
+    "firstKeptEntryId": "abc123",
     "tokensBefore": 150000,
-    "summary": "Summary of conversation..."
+    "details": {}
   },
-  "aborted": false
+  "aborted": false,
+  "willRetry": false
 }
 ```
 
+If `reason` was `"overflow"` and compaction succeeds, `willRetry` is `true` and the agent will automatically retry the prompt.
+
 If compaction was aborted, `result` is `null` and `aborted` is `true`.
 
 ### auto_retry_start / auto_retry_end
@@ -806,7 +815,7 @@ Parse errors:
 
 Source files:
 - [`packages/ai/src/types.ts`](../../ai/src/types.ts) - `Model`, `UserMessage`, `AssistantMessage`, `ToolResultMessage`
-- [`packages/agent/src/types.ts`](../../agent/src/types.ts) - `AppMessage`, `Attachment`, `AgentEvent`
+- [`packages/agent/src/types.ts`](../../agent/src/types.ts) - `AgentMessage`, `AgentEvent`
 - [`src/core/messages.ts`](../src/core/messages.ts) - `BashExecutionMessage`
 - [`src/modes/rpc/rpc-types.ts`](../src/modes/rpc/rpc-types.ts) - RPC command/response types