[FIX] 문서 NUL 문자 정제 및 Discord 알림 길이 제한

ssd-api/src/main/java/or/hyu/ssd/api/document/request/CreateDocumentBlockRequest.java

@@ -37,6 +37,13 @@ public boolean isValidBlockStructure() {
     }
 
     public DocumentBlockCommand toCommand() {
-        return new DocumentBlockCommand(resolvedType(), content, role, blockId, blobKey, url);
+        return new DocumentBlockCommand(
+                resolvedType(),
+                RequestStringSanitizer.stripNullChar(content),
+                RequestStringSanitizer.stripNullChar(role),
+                blockId,
+                RequestStringSanitizer.stripNullChar(blobKey),
+                RequestStringSanitizer.stripNullChar(url)
+        );
     }
 }

ssd-api/src/main/java/or/hyu/ssd/api/document/request/CreateDocumentRequest.java

@@ -21,8 +21,8 @@ public record CreateDocumentRequest(
 ) {
     public CreateDocumentCommand toCommand() {
         return new CreateDocumentCommand(
-                title,
-                text,
+                RequestStringSanitizer.stripNullChar(title),
+                RequestStringSanitizer.stripNullChar(text),
                 paragraphs == null ? null : paragraphs.stream().map(CreateDocumentBlockRequest::toCommand).toList(),
                 folderId,
                 purpose

ssd-api/src/main/java/or/hyu/ssd/api/document/request/RequestStringSanitizer.java

@@ -0,0 +1,14 @@
+package or.hyu.ssd.api.document.request;
+
+final class RequestStringSanitizer {
+
+    private RequestStringSanitizer() {
+    }
+
+    static String stripNullChar(String value) {
+        if (value == null || value.indexOf('\u0000') < 0) {
+            return value;
+        }
+        return value.replace("\u0000", "");
+    }
+}

ssd-api/src/main/java/or/hyu/ssd/api/document/request/UpdateDocumentRequest.java

@@ -14,8 +14,8 @@ public record UpdateDocumentRequest(
 ) {
     public UpdateDocumentCommand toCommand() {
         return new UpdateDocumentCommand(
-                title,
-                text,
+                RequestStringSanitizer.stripNullChar(title),
+                RequestStringSanitizer.stripNullChar(text),
                 paragraphs == null ? null : paragraphs.stream().map(CreateDocumentBlockRequest::toCommand).toList()
         );
     }

ssd-api/src/test/java/or/hyu/ssd/api/document/request/CreateDocumentRequestValidationTest.java

@@ -64,6 +64,29 @@ void purposeRejectsNull() {
                 .contains("문서 목적은 필수입니다");
     }
 
+    @Test
+    @DisplayName("toCommand는 문자열의 NUL 문자(\\u0000)를 제거한다")
+    void toCommandStripsNullCharacter() {
+        // given
+        CreateDocumentRequest request = new CreateDocumentRequest(
+                "제목\u0000",
+                "본문\u0000텍스트",
+                Arrays.asList(new CreateDocumentBlockRequest(null, "문단\u0000내용", "\u0000##", 1, null, null)),
+                0L,
+                DocumentPurpose.WRITING
+        );
+
+        // when
+        var command = request.toCommand();
+
+        // then
+        assertThat(command.title()).isEqualTo("제목");
+        assertThat(command.text()).isEqualTo("본문텍스트");
+        assertThat(command.blocks()).hasSize(1);
+        assertThat(command.blocks().getFirst().content()).isEqualTo("문단내용");
+        assertThat(command.blocks().getFirst().role()).isEqualTo("##");
+    }
+
     private static Set<String> extractMessages(Set<? extends ConstraintViolation<?>> violations) {
         return violations.stream()
                 .map(ConstraintViolation::getMessage)

ssd-external/src/main/java/or/hyu/ssd/external/alert/discord/DiscordWebhookNotifier.java

@@ -26,6 +26,8 @@ public class DiscordWebhookNotifier implements ErrorAlertNotifier {
 
     private static final Duration REQUEST_TIMEOUT = Duration.ofSeconds(5);
     private static final DateTimeFormatter TIME_FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
+    private static final int DISCORD_CONTENT_LIMIT = 2000;
+    private static final String TRUNCATION_SUFFIX = "\n...(truncated)";
 
     private final DiscordProperties discordProperties;
     private final Environment environment;
@@ -120,7 +122,7 @@ private String resolveEnvironment() {
     }
 
     private String buildPayload(String content) {
-        return "{\"content\":\"" + escapeJson(content) + "\"}";
+        return "{\"content\":\"" + escapeJson(truncateForDiscord(content)) + "\"}";
     }
 
     private String escapeJson(String value) {
@@ -130,4 +132,16 @@ private String escapeJson(String value) {
                 .replace("\r", "\\r")
                 .replace("\n", "\\n");
     }
+
+    private String truncateForDiscord(String content) {
+        if (content == null || content.length() <= DISCORD_CONTENT_LIMIT) {
+            return content;
+        }
+
+        int maxPrefixLength = DISCORD_CONTENT_LIMIT - TRUNCATION_SUFFIX.length();
+        if (maxPrefixLength <= 0) {
+            return content.substring(0, DISCORD_CONTENT_LIMIT);
+        }
+        return content.substring(0, maxPrefixLength) + TRUNCATION_SUFFIX;
+    }
 }

ssd-external/src/test/java/or/hyu/ssd/external/alert/discord/DiscordWebhookNotifierTest.java

@@ -0,0 +1,40 @@
+package or.hyu.ssd.external.alert.discord;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.mock.env.MockEnvironment;
+import or.hyu.ssd.external.config.DiscordProperties;
+
+import java.lang.reflect.Method;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class DiscordWebhookNotifierTest {
+
+    @Test
+    @DisplayName("디스코드 본문이 2000자를 넘으면 잘라낸다")
+    void truncateMessageWhenContentTooLong() throws Exception {
+        DiscordWebhookNotifier notifier = new DiscordWebhookNotifier(new DiscordProperties(), new MockEnvironment());
+        Method truncateMethod = DiscordWebhookNotifier.class.getDeclaredMethod("truncateForDiscord", String.class);
+        truncateMethod.setAccessible(true);
+
+        String longMessage = "a".repeat(2100);
+        String truncated = (String) truncateMethod.invoke(notifier, longMessage);
+
+        assertThat(truncated.length()).isLessThanOrEqualTo(2000);
+        assertThat(truncated).endsWith("\n...(truncated)");
+    }
+
+    @Test
+    @DisplayName("디스코드 본문이 2000자 이하면 그대로 둔다")
+    void keepMessageWhenWithinLimit() throws Exception {
+        DiscordWebhookNotifier notifier = new DiscordWebhookNotifier(new DiscordProperties(), new MockEnvironment());
+        Method truncateMethod = DiscordWebhookNotifier.class.getDeclaredMethod("truncateForDiscord", String.class);
+        truncateMethod.setAccessible(true);
+
+        String message = "a".repeat(2000);
+        String truncated = (String) truncateMethod.invoke(notifier, message);
+
+        assertThat(truncated).isEqualTo(message);
+    }
+}