diff --git a/quartz/src/commonTest/kotlin/com/vitorpamplona/quartz/utils/urldetector/UrlTest.kt b/quartz/src/commonTest/kotlin/com/vitorpamplona/quartz/utils/urldetector/UrlTest.kt
new file mode 100644
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--- /dev/null
+++ b/quartz/src/commonTest/kotlin/com/vitorpamplona/quartz/utils/urldetector/UrlTest.kt
@@ -0,0 +1,128 @@
+/*
+ * Copyright (c) 2025 Vitor Pamplona
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
+ * Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package com.vitorpamplona.quartz.utils.urldetector
+
+import com.vitorpamplona.quartz.utils.urldetector.detection.UrlDetector
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertNotNull
+
+/**
+ * Tests for [Url.getPart] boundary conditions fixed in PR #1907.
+ *
+ * When [com.vitorpamplona.quartz.utils.urldetector.detection.UrlDetector] trims the last
+ * character of a detected URL (because it is in CANNOT_END_URLS_WITH, e.g. ':'), the
+ * [UrlMarker] indices remain based on the original buffer length. This can leave a part's
+ * start index or the next part's end index pointing past the end of the trimmed [Url.originalUrl],
+ * causing a [StringIndexOutOfBoundsException] in [Url.getPart].
+ *
+ * The fix guards against `startIndex >= originalUrl.length` (returns null) and clamps
+ * `endIndex` via `minOf(endIndex, originalUrl.length)`.
+ */
+class UrlTest {
+    /**
+     * Simulates a URL whose trailing ':' was trimmed by readEnd(), leaving the PORT marker
+     * at index == originalUrl.length. Regression for the "今北産業" crash (PR #1907).
+     *
+     * Without the fix, getPart(HOST) called substring(0, 11) on an 11-char string which
+     * is fine, but getPart(PORT) called substring(11) – or in the old code substring(11, <next>)
+     * – with startIndex == length, causing StringIndexOutOfBoundsException.
+     */
+    @Test
+    fun getPartDoesNotThrowWhenPortIndexEqualsStringLength() {
+        // "example.com" is 11 chars; PORT marker at 11 == length simulates "example.com:"
+        // after the trailing ':' was stripped by readEnd().
+        val marker = UrlMarker()
+        marker.setIndex(UrlPart.HOST, 0)
+        marker.setIndex(UrlPart.PORT, 11) // == originalUrl.length
+        val url = marker.createUrl("example.com")
+
+        assertEquals("example.com", url.host)
+        assertEquals(-1, url.port) // getPart(PORT) returns null → falls back to -1
+    }
+
+    /**
+     * Simulates a URL whose trailing ':' was trimmed, leaving PORT marker one position
+     * beyond originalUrl.length. getPart must clamp via minOf and not throw.
+     */
+    @Test
+    fun getPartDoesNotThrowWhenPortIndexExceedsStringLength() {
+        val marker = UrlMarker()
+        marker.setIndex(UrlPart.HOST, 0)
+        marker.setIndex(UrlPart.PORT, 12) // > originalUrl.length (11)
+        val url = marker.createUrl("example.com")
+
+        assertEquals("example.com", url.host)
+        assertEquals(-1, url.port)
+    }
+
+    /**
+     * Simulates a URL whose trailing '?' was trimmed, leaving the QUERY marker at
+     * index == originalUrl.length. getPart(PATH) must clamp its endIndex and not throw.
+     */
+    @Test
+    fun getPartDoesNotThrowWhenQueryIndexEqualsStringLength() {
+        // "example.com/a" is 14 chars; QUERY at 14 simulates "example.com/a?" after trim.
+        val marker = UrlMarker()
+        marker.setIndex(UrlPart.HOST, 0)
+        marker.setIndex(UrlPart.PATH, 11)
+        marker.setIndex(UrlPart.QUERY, 14) // == originalUrl.length
+        val url = marker.createUrl("example.com/a")
+
+        assertEquals("example.com", url.host)
+        assertEquals("/a", url.path)
+        assertEquals("", url.query) // getPart(QUERY) startIndex >= length → null → ""
+    }
+
+    /**
+     * Regression test for PR #1907: the Japanese phrase "今北産業" (the crash trigger)
+     * must not cause a StringIndexOutOfBoundsException when detected URLs have their
+     * parts accessed, and must produce no URLs.
+     */
+    @Test
+    fun detectingJapaneseTextDoesNotThrow() {
+        val urls = UrlDetector("今北産業").detect()
+        assertEquals(0, urls.size)
+    }
+
+    /**
+     * Ensures that even if a Url with out-of-range markers somehow reaches property
+     * access, all properties return gracefully without throwing.
+     */
+    @Test
+    fun allPropertiesAreSafeWithOutOfRangeMarkers() {
+        val marker = UrlMarker()
+        marker.setIndex(UrlPart.SCHEME, 0)
+        marker.setIndex(UrlPart.HOST, 8)
+        marker.setIndex(UrlPart.PORT, 20) // beyond the 19-char string length
+        val url = marker.createUrl("https://example.com") // 19 chars
+
+        assertNotNull(url.scheme)
+        assertNotNull(url.host)
+        assertNotNull(url.username)
+        assertNotNull(url.password)
+        assertNotNull(url.path)
+        assertNotNull(url.query)
+        assertNotNull(url.fragment)
+        // port returns -1 when getPart returns null
+        assertEquals(-1, url.port)
+    }
+}