fix: sessions paginationとhealth診断を改善

- sessions cursorのエンコード不具合と長いsession IDのバッファ問題を修正
- response budgetに基づくsessionsページングを追加
- get_system_healthにsession_countを追加
- metadata_jsonのフィールド別エラー診断を追加
- CRUD互換性とDebug/Release/ASanテストを確認

1 files changed, 18 insertions, 4 deletions

diff --git a/src/mcp/tools/update_message.c b/src/mcp/tools/update_message.c
index aca1bed..9b02a6f 100644
--- a/src/mcp/tools/update_message.c
+++ b/src/mcp/tools/update_message.c
@@ -22,6 +22,8 @@ call_update_message(const mcpc_tool_t *tool, mcpc_ucbr_t *result)
   tiny_json_buffer_t json;
   bool changed = false;
   tiny_metadata_mask_t metadata_mask = 0;
+  const char *metadata_error = NULL;
+  tiny_metadata_parse_status_t metadata_status = TINY_METADATA_PARSE_OK;
   tiny_message_init(&parsed);
   tiny_message_init(&updated);
   patch.content = content;
@@ -29,10 +31,22 @@ call_update_message(const mcpc_tool_t *tool, mcpc_ucbr_t *result)
   patch.metadata_mask = 0;
   patch.expected_revision = (uint64_t)expected;
   patch.has_expected_revision = expected_status == MCPC_EC_0;
-  if (!context || !message_id || (!content && !metadata_json)
-      || (metadata_json && !tiny_mcp_parse_metadata(metadata_json, &parsed, &metadata_mask))
-      || (expected_status != MCPC_EC_0 && expected_status != MCPC_EC_ANYDATA_NOTFOUND)
-      || (patch.has_expected_revision && expected < 1))
+  if (metadata_json)
+    {
+      metadata_status
+          = tiny_mcp_parse_metadata(metadata_json, &parsed, &metadata_mask, &metadata_error);
+    }
+  if (metadata_status == TINY_METADATA_PARSE_NO_MEMORY)
+    {
+      tiny_mcp_tool_add_error(result, "INTERNAL_ERROR", metadata_error);
+    }
+  else if (metadata_status == TINY_METADATA_PARSE_INVALID)
+    {
+      tiny_mcp_tool_add_error(result, "VALIDATION_ERROR", metadata_error);
+    }
+  else if (!context || !message_id || (!content && !metadata_json)
+           || (expected_status != MCPC_EC_0 && expected_status != MCPC_EC_ANYDATA_NOTFOUND)
+           || (patch.has_expected_revision && expected < 1))
     {
       tiny_mcp_tool_add_error(result, "VALIDATION_ERROR", "invalid update_message arguments");
     }