refactor: extract AiText and detect foreign-script leakage

Moves sanitise out of the Bukkit-bound Ai class so it can be unit
tested, and adds hasForeignScript to catch the CJK words the model
intermittently drops into Portuguese answers.

Colour-code stripping now removes the code character too: replacing
only the section sign left "§c" reading as a stray "c" in chat.

Surefire now fails on an empty suite, so a misplaced or disabled test
class cannot pass as a green build.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01F3jSvSTrG4qsniLSr6TpC6

pom.xml

@@ -68,6 +68,13 @@
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-surefire-plugin</artifactId>
         <version>3.5.4</version>
+        <configuration>
+          <!-- The pin above guards against a surefire version that quietly stops
+               discovering tests. It does not guard against a test class being
+               misplaced, misnamed or disabled, which ends the same way: a green
+               build that ran nothing. Failing on an empty suite closes that gap. -->
+          <failIfNoTests>true</failIfNoTests>
+        </configuration>
       </plugin>
     </plugins>
   </build>

src/main/java/dev/marcospaulo/canalhandia/Ai.java

@@ -32,7 +32,7 @@ import java.util.UUID;
  * dispatcher, never written to disk, and no tool/function definitions are sent
  * in the request, so there is nothing for the model to call. A player asking it
  * to "run /op me" gets a string back, not an executed command. As a second
- * layer, {@link #sanitise} strips leading slashes so a reply cannot even be
+ * layer, {@link AiText#sanitise} strips leading slashes so a reply cannot even be
  * mistaken for a command someone should paste.
  *
  * <p>The API key never lives in config.yml, because config.yml is committed to
@@ -157,7 +157,7 @@ final class Ai {
             return;
         }
         Component message = Msg.tag("IA", NamedTextColor.LIGHT_PURPLE)
-                .append(Component.text(sanitise(answer, settings.aiMaxAnswer()), NamedTextColor.WHITE)
+                .append(Component.text(AiText.sanitise(answer, settings.aiMaxAnswer()), NamedTextColor.WHITE)
                         .decoration(TextDecoration.BOLD, false));
         if (settings.aiPublic()) {
             Bukkit.broadcast(message);
@@ -190,7 +190,7 @@ final class Ai {
         HttpResponse<String> response = http.send(request, HttpResponse.BodyHandlers.ofString());
         if (response.statusCode() / 100 != 2) {
             plugin.getLogger().warning("IA respondeu HTTP " + response.statusCode() + ": "
-                    + trim(response.body()));
+                    + AiText.forLog(response.body()));
             return null;
         }
         return extract(response.body());
@@ -263,39 +263,4 @@ final class Ai {
         return askedToday;
     }
 
-    /**
-     * Makes a model reply safe and readable in chat.
-     *
-     * <p>Strips colour codes so the reply cannot forge server messages, folds
-     * newlines so one answer stays one chat entry, and removes leading slashes
-     * so nothing that comes back reads as a command to run.
-     *
-     * <p>It also strips markdown and emoji, which the models emit freely.
-     * Minecraft chat renders neither: {@code **negrito**} arrives as literal
-     * asterisks, and emoji show up as empty boxes on Bedrock.
-     */
-    static String sanitise(String raw, int max) {
-        String text = raw.replace('§', ' ')
-                .replaceAll("[\\r\\n]+", " ")
-                // Markdown emphasis and code fences: chat shows the characters, not the effect.
-                .replaceAll("\\*{1,3}([^*]+)\\*{1,3}", "$1")
-                .replaceAll("`{1,3}([^`]+)`{1,3}", "$1")
-                .replaceAll("^#{1,6}\\s+", "")
-                // Emoji live outside the BMP, plus the symbol blocks and the
-                // variation selector. Accented pt-BR letters are far below this.
-                .replaceAll("[\\x{1F000}-\\x{1FAFF}\\x{2190}-\\x{2BFF}\\x{FE0F}\\x{20E3}]", "")
-                .replaceAll("\\s{2,}", " ")
-                .trim();
-        while (text.startsWith("/")) {
-            text = text.substring(1).trim();
-        }
-        if (text.length() > max) {
-            text = text.substring(0, max).trim() + "…";
-        }
-        return text;
-    }
-
-    private static String trim(String text) {
-        return text.length() > 300 ? text.substring(0, 300) + "…" : text;
-    }
 }

src/main/java/dev/marcospaulo/canalhandia/AiText.java

@@ -0,0 +1,59 @@
+package dev.marcospaulo.canalhandia;
+
+import java.util.regex.Pattern;
+
+/**
+ * Text guards for model replies.
+ *
+ * <p>Pure functions, deliberately free of Bukkit, so they can be tested without
+ * a server.
+ */
+final class AiText {
+
+    /**
+     * Scripts that should never appear in a Portuguese answer. The model has
+     * been observed dropping single Chinese words mid-sentence.
+     */
+    private static final Pattern FOREIGN = Pattern.compile(
+            "[\\p{IsHan}\\p{IsHiragana}\\p{IsKatakana}\\p{IsHangul}\\p{IsCyrillic}\\p{IsArabic}]");
+
+    private AiText() {
+    }
+
+    static boolean hasForeignScript(String text) {
+        return text != null && FOREIGN.matcher(text).find();
+    }
+
+    /**
+     * Makes a reply safe and readable in chat: no colour codes to forge server
+     * messages, no markdown or emoji (chat renders neither, and emoji are empty
+     * boxes on Bedrock), no leading slash that could read as a command.
+     */
+    static String sanitise(String raw, int max) {
+        String text = raw
+                // A colour code is the section sign plus the code character, so both
+                // go. Dropping only the sign would leave the bare letter behind and
+                // "§c" would read as a stray "c" in the middle of the sentence.
+                .replaceAll("§[0-9A-Za-z]", " ")
+                .replace('§', ' ')
+                .replaceAll("[\\r\\n]+", " ")
+                .replaceAll("\\*{1,3}([^*]+)\\*{1,3}", "$1")
+                .replaceAll("`{1,3}([^`]+)`{1,3}", "$1")
+                .replaceAll("^#{1,6}\\s+", "")
+                .replaceAll("[\\x{1F000}-\\x{1FAFF}\\x{2190}-\\x{2BFF}\\x{FE0F}\\x{20E3}]", "")
+                .replaceAll("\\s{2,}", " ")
+                .trim();
+        while (text.startsWith("/")) {
+            text = text.substring(1).trim();
+        }
+        if (text.length() > max) {
+            text = text.substring(0, max).trim() + "…";
+        }
+        return text;
+    }
+
+    /** Shortens text for a log line. */
+    static String forLog(String text) {
+        return text.length() > 300 ? text.substring(0, 300) + "…" : text;
+    }
+}

src/test/java/dev/marcospaulo/canalhandia/AiTextTest.java

@@ -0,0 +1,47 @@
+package dev.marcospaulo.canalhandia;
+
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+class AiTextTest {
+
+    @Test
+    void stripsMarkdownEmphasis() {
+        assertEquals("use magma cream",
+                AiText.sanitise("use **magma cream**", 500));
+    }
+
+    @Test
+    void stripsEmojiAndSectionSigns() {
+        assertEquals("boa sorte",
+                AiText.sanitise("boa sorte 😄 §c", 500));
+    }
+
+    @Test
+    void stripsLeadingSlashesSoRepliesCannotLookLikeCommands() {
+        assertEquals("give me diamonds",
+                AiText.sanitise("//give me diamonds", 500));
+    }
+
+    @Test
+    void keepsPortugueseAccents() {
+        assertEquals("poção de resistência ao fogo",
+                AiText.sanitise("poção de resistência ao fogo", 500));
+    }
+
+    @Test
+    void truncatesToLimit() {
+        assertEquals("abc…", AiText.sanitise("abcdefg", 3));
+    }
+
+    // The model leaked "搭档" and "contiennent" into Portuguese answers.
+    @Test
+    void detectsCjk() {
+        assertTrue(AiText.hasForeignScript("te aceite como搭档"));
+    }
+
+    @Test
+    void plainPortugueseIsNotForeign() {
+        assertFalse(AiText.hasForeignScript("camelos são pacíficos e mansos"));
+    }
+}