diff --git a/htdocs/comm/card.php b/htdocs/comm/card.php
index 8b4949cd770..e39eb7abafc 100644
--- a/htdocs/comm/card.php
+++ b/htdocs/comm/card.php
@@ -65,7 +65,7 @@ if (isModEnabled('ficheinter')) {
 }
 
 // Load translation files required by the page
-$langs->loadLangs(array('companies', 'banks'));
+$langs->loadLangs(array('companies', 'banks', 'commercial'));
 
 if (isModEnabled('contrat')) {
 	$langs->load("contracts");
diff --git a/htdocs/core/lib/date.lib.php b/htdocs/core/lib/date.lib.php
index fb57502d6fe..ed7e8181601 100644
--- a/htdocs/core/lib/date.lib.php
+++ b/htdocs/core/lib/date.lib.php
@@ -1033,16 +1033,35 @@ function num_open_day($timestampStart, $timestampEnd, $inhour = 0, $lastday = 0,
 		return 'ErrorBadParameter_num_open_day';
 	}
 
-	//print 'num_open_day timestampStart='.$timestampStart.' timestampEnd='.$timestampEnd.' bit='.$lastday;
 	if ($timestampStart < $timestampEnd) {
-		$numdays = num_between_day($timestampStart, $timestampEnd, $lastday);
+		// --- 1. Calculate Gross Working Days ---
+		// Gross working days = total days in range - non-working days (weekends & public holidays).
+		$nbOpenDay = num_between_day($timestampStart, $timestampEnd, $lastday) - num_public_holiday($timestampStart, $timestampEnd, $country_code, $lastday);
 
-		$numholidays = num_public_holiday($timestampStart, $timestampEnd, $country_code, $lastday);
-		$nbOpenDay = ($numdays - $numholidays);
-		if ($inhour == 1 && $nbOpenDay <= 3) {
-			$nbOpenDay = ($nbOpenDay * 24);
+		// --- 2. Apply Contextual Half-Day Deductions ---
+		$halfday = (int) $halfday; // Ensure $halfday is an integer for reliable comparisons.
+
+		// Check if start/end days are working days just ONCE to optimize performance
+		// by avoiding redundant calls to the potentially slow num_public_holiday() function.
+		$isStartDayWorking = (num_public_holiday($timestampStart, $timestampStart, $country_code, 1) == 0);
+		$isEndDayWorking   = (num_public_holiday($timestampEnd, $timestampEnd, $country_code, 1) == 0);
+
+		// Deduct 0.5 if the leave starts in the afternoon of a working day.
+		if (($halfday == -1 || $halfday == 2) && $isStartDayWorking) {
+			$nbOpenDay -= 0.5;
 		}
-		return $nbOpenDay - (($inhour == 1 ? 12 : 0.5) * abs($halfday));
+
+		// Deduct 0.5 if the leave ends in the morning of a different, working day.
+		if (($halfday == 1 || $halfday == 2) && date('Y-m-d', $timestampStart) != date('Y-m-d', $timestampEnd) && $isEndDayWorking) {
+			$nbOpenDay -= 0.5;
+		}
+
+		// --- 3. Return Final Value ---
+		if ($inhour == 1) {
+			return $nbOpenDay * 24;
+		}
+
+		return $nbOpenDay;
 	} elseif ($timestampStart == $timestampEnd) {
 		$numholidays = 0;
 		if ($lastday) {
diff --git a/test/phpunit/DateLibTest.php b/test/phpunit/DateLibTest.php
index 428b55de164..8f2e29617d5 100644
--- a/test/phpunit/DateLibTest.php
+++ b/test/phpunit/DateLibTest.php
@@ -305,6 +305,42 @@ class DateLibTest extends PHPUnit\Framework\TestCase
 		$result=num_open_day($date1, $date2, 'XX', 1);
 		print __METHOD__." result=".$result."\n";
 		$this->assertEquals(3, $result, 'NumOpenDay for XX when saturday + sunday are working days');   // 3 opened day, 0 closes (even if country unknown)
+
+		// Define specific dates for these tests
+		$date_friday_4 = dol_mktime(0, 0, 0, 1, 4, 2013, 'gmt');   // Friday
+		$date_saturday_5 = dol_mktime(0, 0, 0, 1, 5, 2013, 'gmt'); // Saturday
+		$date_monday_7 = dol_mktime(0, 0, 0, 1, 7, 2013, 'gmt');   // Monday
+		$date_friday_11 = dol_mktime(0, 0, 0, 1, 11, 2013, 'gmt');  // Following Friday
+
+		// Case 1: Weekend Boundary (Friday morning -> Saturday morning)
+		// Expected: 1 day. No half-day deduction for end date on a non-working day.
+		// $starthalfday = 'morning', $endhalfday = 'morning' -> $halfday = 1
+		$conf->global->MAIN_NON_WORKING_DAYS_INCLUDE_SATURDAY = 1;
+		$conf->global->MAIN_NON_WORKING_DAYS_INCLUDE_SUNDAY = 1;
+		$result = num_open_day($date_friday_4, $date_saturday_5, 0, 1, 1, 'FR');
+		print __METHOD__." result=".$result."\n";
+		$this->assertEquals(1, $result, 'Case 1: Friday morning to Saturday morning should be 1 day');
+
+		// Case 2: Full week with half-day (Friday morning -> Following Friday morning)
+		// Expected: 5.5 days.
+		// $starthalfday = 'morning', $endhalfday = 'morning' -> $halfday = 1
+		$result = num_open_day($date_friday_4, $date_friday_11, 0, 1, 1, 'FR');
+		print __METHOD__." result=".$result."\n";
+		$this->assertEquals(5.5, $result, 'Case 2: Friday morning to next Friday morning should be 5.5 days');
+
+		// Case 3: Single Half-Day (Monday afternoon)
+		// Expected: 0.5 days.
+		// $starthalfday = 'afternoon' -> $halfday = -1
+		$result = num_open_day($date_monday_7, $date_monday_7, 0, 1, -1, 'FR');
+		print __METHOD__." result=".$result."\n";
+		$this->assertEquals(0.5, $result, 'Case 3: A single Monday afternoon should be 0.5 days');
+
+		// Case 4: Standard Leave (Monday morning -> Friday evening)
+		// Expected: 5 days.
+		// $starthalfday = 'morning', $endhalfday = 'evening' -> $halfday = 0
+		$result = num_open_day($date_monday_7, $date_friday_11, 0, 1, 0, 'FR');
+		print __METHOD__." result=".$result."\n";
+		$this->assertEquals(5, $result, 'Case 4: Monday morning to Friday evening should be 5 days');
 	}
 
 	/**