fix: address PR review feedback

- Wrap bridge_metadata parsing with guardTopLevelUnknown for consistency
- Add @jsonField("slash_commands") annotation for JSON round-trip correctness
- Restore caret in package.json version specifier
- Add edge-case tests: StopFailure with missing error, empty slash_commands

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: arcaputo3

bun.lock

@@ -10,7 +10,7 @@
   },
   "dependencies": {
     "@a2a-js/sdk": "^0.3.12",
-    "@anthropic-ai/claude-agent-sdk": "0.2.78",
+    "@anthropic-ai/claude-agent-sdk": "^0.2.78",
     "zod": "^4.0.0"
   },
   "devDependencies": {

package.json

@@ -168,7 +168,7 @@ enum AgentMessage:
 
   /** Bridge metadata message carrying slash commands */
   case BridgeMetadata(
-      slashCommands: List[String],
+      @jsonField("slash_commands") slashCommands: List[String],
       uuid: MessageUuid,
       sessionId: SessionId
   )

src/com/tjclp/scalagent/messages/AgentMessage.scala

@@ -204,11 +204,13 @@ object MessageConverter:
           parseApiRetryMessage(obj, raw)
         }
       case Some("bridge_metadata") =>
-        AgentMessage.BridgeMetadata(
-          slashCommands = stringArrayField(obj, "slash_commands"),
-          uuid = requiredUuid(obj, raw),
-          sessionId = requiredSessionId(obj, raw)
-        )
+        guardTopLevelUnknown(raw, "system", Some("bridge_metadata"), context) {
+          AgentMessage.BridgeMetadata(
+            slashCommands = stringArrayField(obj, "slash_commands"),
+            uuid = requiredUuid(obj, raw),
+            sessionId = requiredSessionId(obj, raw)
+          )
+        }
       case other =>
         AgentMessage.System(
           event = parseSystemEvent(obj, raw, other, context),

src/com/tjclp/scalagent/streaming/MessageConverter.scala

@@ -182,6 +182,17 @@ class HookCallbackSpec extends FunSuite:
       case other => fail(s"Expected StopFailure, got: $other")
     }
 
+  test("parseHookInput handles StopFailure with missing error defaults to Unknown"):
+    val raw = baseInput("StopFailure")
+
+    parseInput(raw).map {
+      case input: HookInput.StopFailure =>
+        assertEquals(input.error, AssistantMessageError.Unknown)
+        assertEquals(input.errorDetails, None)
+        assertEquals(input.lastAssistantMessage, None)
+      case other => fail(s"Expected StopFailure, got: $other")
+    }
+
   test("parseHookInput handles InstructionsLoaded with agent metadata"):
     val raw = baseInput("InstructionsLoaded")
     raw.file_path = "/tmp/project/CLAUDE.md"

test/src/com/tjclp/scalagent/hooks/HookCallbackSpec.scala

@@ -403,6 +403,21 @@ class MessageConverterSpec extends FunSuite:
       case other =>
         fail(s"Expected BridgeMetadata, got: $other")
 
+  test("parses bridge_metadata with empty slash_commands"):
+    val raw = js.Dynamic.literal(
+      `type` = "system",
+      subtype = "bridge_metadata",
+      slash_commands = js.Array[String](),
+      uuid = "msg-bridge-2",
+      session_id = "session-1"
+    )
+
+    MessageConverter.fromRaw(raw) match
+      case AgentMessage.BridgeMetadata(slashCommands, _, _) =>
+        assertEquals(slashCommands, Nil)
+      case other =>
+        fail(s"Expected BridgeMetadata, got: $other")
+
   test("parses task_progress with summary"):
     val raw = js.Dynamic.literal(
       `type` = "system",