diff --git a/src/State/EmployeeLeaveSummaryProvider.php b/src/State/EmployeeLeaveSummaryProvider.php
index 43d26fc..dc0a53d 100644
--- a/src/State/EmployeeLeaveSummaryProvider.php
+++ b/src/State/EmployeeLeaveSummaryProvider.php
@@ -7,6 +7,7 @@ namespace App\State;
 use ApiPlatform\Metadata\Operation;
 use ApiPlatform\State\ProviderInterface;
 use App\ApiResource\EmployeeLeaveSummary;
+use App\Dto\Contracts\ContractPhase;
 use App\Entity\Absence;
 use App\Entity\ContractSuspension;
 use App\Entity\Employee;
@@ -20,6 +21,7 @@ use App\Repository\EmployeeLeaveBalanceRepository;
 use App\Repository\EmployeeRepository;
 use App\Repository\WorkHourRepository;
 use App\Security\EmployeeScopeService;
+use App\Service\Contracts\EmployeeContractPhaseResolver;
 use App\Service\Leave\LeaveBalanceComputationService;
 use App\Service\Leave\LongMaladieService;
 use App\Service\Leave\SuspensionDaysCalculator;
@@ -60,6 +62,7 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
         private PublicHolidayServiceInterface $publicHolidayService,
         private SuspensionDaysCalculator $suspensionDaysCalculator,
         private WorkHourRepository $workHourRepository,
+        private EmployeeContractPhaseResolver $phaseResolver,
         string $dataStartDate = '',
     ) {
         $this->dataStartDate = '' !== $dataStartDate ? $dataStartDate : null;
@@ -86,14 +89,15 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
             throw new AccessDeniedHttpException('Employee outside your scope.');
         }
 
-        $year = $this->resolveYear($employee);
+        $phase = $this->resolveTargetPhase($employee);
+        $year  = $this->resolveYear($employee, $phase);
 
         $summary                = new EmployeeLeaveSummary();
         $summary->year          = $year;
         $summary->ruleCode      = LeaveRuleCode::UNSUPPORTED->value;
         $summary->dataStartDate = $this->dataStartDate;
 
-        $yearSummary = $this->computeYearSummary($employee, $year);
+        $yearSummary = $this->computeYearSummary($employee, $year, 0.0, null, $phase);
         if (null === $yearSummary) {
             return $summary;
         }
@@ -104,7 +108,7 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
         // For forfait contracts, paid days reduce N-1 stock before taken-day attribution.
         // Recompute with paidLeaveDays so taken days shift from N-1 to N when N-1 is consumed by payment.
         if ($paidLeaveDays > 0.0) {
-            $yearSummary = $this->computeYearSummary($employee, $year, $paidLeaveDays);
+            $yearSummary = $this->computeYearSummary($employee, $year, $paidLeaveDays, null, $phase);
             if (null === $yearSummary) {
                 return $summary;
             }
@@ -125,7 +129,7 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
         $summary->previousYearRemainingDays = $yearSummary['previousYearRemainingDays'];
         $summary->previousYearPaidDays      = $paidLeaveDays;
 
-        [$periodFrom, $periodTo] = $this->resolvePeriodBounds($employee, $year);
+        [$periodFrom, $periodTo] = $this->resolvePeriodBounds($employee, $year, $phase);
         // Forfait-only: leaves taken from N-1 stock do NOT decrement presence days.
         // For non-forfait, previousYearTakenDays is always 0, so the budget has no effect.
         $n1AbsencesBudget             = $yearSummary['previousYearTakenDays'];
@@ -167,9 +171,14 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
      *   previousYearRemainingDays: float
      * }
      */
-    public function computeYearSummary(Employee $employee, int $targetYear, float $paidLeaveDays = 0.0, ?DateTimeImmutable $asOfDate = null): ?array
+    public function computeYearSummary(Employee $employee, int $targetYear, float $paidLeaveDays = 0.0, ?DateTimeImmutable $asOfDate = null, ?ContractPhase $phase = null): ?array
     {
-        $firstYear = max($this->resolveFirstComputationYear($employee), $targetYear - 1);
+        $phase ??= $this->resolveCurrentPhase($employee);
+        if (null === $phase) {
+            return null;
+        }
+
+        $firstYear = max($this->resolveFirstComputationYear($employee, $phase), $targetYear - 1);
         if ($targetYear < $firstYear) {
             $targetYear = $firstYear;
         }
@@ -179,8 +188,8 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
         $targetSummary              = null;
 
         for ($year = $firstYear; $year <= $targetYear; ++$year) {
-            [$from, $to] = $this->resolvePeriodBounds($employee, $year);
-            $leavePolicy = $this->resolveLeavePolicy($employee, $from, $to);
+            [$from, $to] = $this->resolvePeriodBounds($employee, $year, $phase);
+            $leavePolicy = $this->resolveLeavePolicy($employee, $phase, $from, $to);
             if (null === $leavePolicy) {
                 if ($year === $targetYear) {
                     return null;
@@ -224,8 +233,8 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
             }
 
             $effectiveAsOfDate     = ($year === $targetYear) ? $asOfDate : null;
-            $accrualCalculationEnd = $this->resolveAccrualCalculationEndDate($leavePolicy['ruleCode'], $year, $to, $employee, $effectiveAsOfDate);
-            $takenCalculationEnd   = $this->resolveTakenCalculationEndDate($to, $employee, $effectiveAsOfDate);
+            $accrualCalculationEnd = $this->resolveAccrualCalculationEndDate($leavePolicy['ruleCode'], $year, $to, $employee, $phase, $effectiveAsOfDate);
+            $takenCalculationEnd   = $this->resolveTakenCalculationEndDate($to, $employee, $phase, $effectiveAsOfDate);
             $suspensions           = $this->suspensionDaysCalculator->applyFirstMonthGrace(
                 $this->resolveSuspensionsForPeriod($employee, $effectiveFrom, $to)
             );
@@ -233,7 +242,7 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
             $longMaladiePeriods         = [];
             $longMaladieReductionFactor = 1.0;
             if (LeaveRuleCode::CDI_CDD_NON_FORFAIT->value === $leavePolicy['ruleCode']
-                && 4 !== $employee->getContract()?->getWeeklyHours()
+                && 4 !== $phase->weeklyHours
                 && null !== $accrualCalculationEnd
             ) {
                 $longMaladiePeriods = $this->longMaladieService->findReducedRatePeriods($employee, $effectiveFrom, $accrualCalculationEnd);
@@ -420,16 +429,29 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
         return $earliest;
     }
 
-    private function resolveYear(Employee $employee): int
+    private function resolveYear(Employee $employee, ContractPhase $phase): int
     {
-        $raw = (string) ($this->requestStack->getCurrentRequest()?->query->get('year') ?? '');
+        $isForfait       = ContractType::FORFAIT === $phase->contractType;
+        $raw             = (string) ($this->requestStack->getCurrentRequest()?->query->get('year') ?? '');
+        $phaseIdRaw      = $this->requestStack->getCurrentRequest()?->query->get('phaseId');
+        $phaseIdProvided = null !== $phaseIdRaw && '' !== (string) $phaseIdRaw;
+
         if ('' === $raw) {
-            $today = new DateTimeImmutable('today');
-            if (ContractType::FORFAIT === $employee->getContract()?->getType()) {
-                return (int) $today->format('Y');
+            // When a phaseId is explicitly provided, default to the year derived from
+            // the phase's end date (or today if the phase is still current).
+            if ($phaseIdProvided) {
+                $reference = $phase->endDate ?? new DateTimeImmutable('today');
+
+                return $isForfait
+                    ? (int) $reference->format('Y')
+                    : $this->resolveCurrentLeaveYear($reference);
             }
 
-            return $this->resolveCurrentLeaveYear($today);
+            $today = new DateTimeImmutable('today');
+
+            return $isForfait
+                ? (int) $today->format('Y')
+                : $this->resolveCurrentLeaveYear($today);
         }
 
         if (!preg_match('/^\d{4}$/', $raw)) {
@@ -441,9 +463,90 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
             throw new UnprocessableEntityHttpException('year must be between 2000 and 2100.');
         }
 
+        // When a phaseId is explicit, silently clamp the requested year to the
+        // first/last exercise covered by the phase.
+        if ($phaseIdProvided) {
+            $year = $this->clampYearToPhase($year, $phase, $isForfait);
+        }
+
         return $year;
     }
 
+    private function clampYearToPhase(int $year, ContractPhase $phase, bool $isForfait): int
+    {
+        $firstYear = $isForfait
+            ? (int) $phase->startDate->format('Y')
+            : ((int) $phase->startDate->format('n') >= 6
+                ? (int) $phase->startDate->format('Y') + 1
+                : (int) $phase->startDate->format('Y'));
+
+        $endDate  = $phase->endDate;
+        $lastYear = null;
+        if ($endDate instanceof DateTimeImmutable) {
+            $lastYear = $isForfait
+                ? (int) $endDate->format('Y')
+                : ((int) $endDate->format('n') >= 6
+                    ? (int) $endDate->format('Y') + 1
+                    : (int) $endDate->format('Y'));
+        }
+
+        if ($year < $firstYear) {
+            return $firstYear;
+        }
+        if (null !== $lastYear && $year > $lastYear) {
+            return $lastYear;
+        }
+
+        return $year;
+    }
+
+    private function resolveTargetPhase(Employee $employee): ContractPhase
+    {
+        $raw    = $this->requestStack->getCurrentRequest()?->query->get('phaseId');
+        $phases = $this->phaseResolver->resolvePhases($employee);
+        if ([] === $phases) {
+            throw new UnprocessableEntityHttpException('Employee has no contract phase.');
+        }
+
+        if (null === $raw || '' === (string) $raw) {
+            // Phase courante par défaut = celle marquée isCurrent ou, à défaut, la plus récente.
+            foreach ($phases as $phase) {
+                if ($phase->isCurrent) {
+                    return $phase;
+                }
+            }
+
+            return $phases[0];
+        }
+
+        if (!preg_match('/^\d+$/', (string) $raw)) {
+            throw new UnprocessableEntityHttpException('phaseId must be a positive integer.');
+        }
+        $phaseId = (int) $raw;
+        foreach ($phases as $phase) {
+            if ($phase->id === $phaseId) {
+                return $phase;
+            }
+        }
+
+        throw new UnprocessableEntityHttpException('phaseId does not match any phase of this employee.');
+    }
+
+    private function resolveCurrentPhase(Employee $employee): ?ContractPhase
+    {
+        $phases = $this->phaseResolver->resolvePhases($employee);
+        if ([] === $phases) {
+            return null;
+        }
+        foreach ($phases as $phase) {
+            if ($phase->isCurrent) {
+                return $phase;
+            }
+        }
+
+        return $phases[0];
+    }
+
     /**
      * @param list<ContractSuspension>                                      $suspensions
      * @param list<array{start: DateTimeImmutable, end: DateTimeImmutable}> $longMaladiePeriods
@@ -518,6 +621,7 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
         int $year,
         DateTimeImmutable $periodEnd,
         Employee $employee,
+        ContractPhase $phase,
         ?DateTimeImmutable $asOfDate = null
     ): ?DateTimeImmutable {
         $reference   = $asOfDate ?? new DateTimeImmutable('today');
@@ -525,7 +629,11 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
             ? (int) $reference->format('Y')
             : $this->resolveCurrentLeaveYear($reference);
 
-        if ($year < $currentYear) {
+        // When viewing a closed phase, treat its end date as the reference cutoff:
+        // accrual is bounded to the phase end, never running to "today".
+        if (!$phase->isCurrent && null !== $phase->endDate) {
+            $end = $phase->endDate < $periodEnd ? $phase->endDate : $periodEnd;
+        } elseif ($year < $currentYear) {
             $end = $periodEnd;
         } elseif ($year > $currentYear) {
             $end = null;
@@ -538,12 +646,15 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
             $end = $lastDayPreviousMonth < $periodEnd ? $lastDayPreviousMonth : $periodEnd;
         }
 
-        // Cap at contract end date if the employee has left.
-        $contractEndRaw = $employee->getCurrentContractEndDate();
-        if (null !== $end && null !== $contractEndRaw && '' !== trim($contractEndRaw)) {
-            $contractEnd = $this->parseYmdDate($contractEndRaw);
-            if ($contractEnd instanceof DateTimeImmutable && $contractEnd < $end) {
-                $end = $contractEnd;
+        // Cap at contract end date if the employee has left (only meaningful when
+        // viewing the current phase; closed phases are already capped above).
+        if ($phase->isCurrent) {
+            $contractEndRaw = $employee->getCurrentContractEndDate();
+            if (null !== $end && null !== $contractEndRaw && '' !== trim($contractEndRaw)) {
+                $contractEnd = $this->parseYmdDate($contractEndRaw);
+                if ($contractEnd instanceof DateTimeImmutable && $contractEnd < $end) {
+                    $end = $contractEnd;
+                }
             }
         }
 
@@ -553,6 +664,7 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
     private function resolveTakenCalculationEndDate(
         DateTimeImmutable $periodEnd,
         Employee $employee,
+        ContractPhase $phase,
         ?DateTimeImmutable $asOfDate = null
     ): ?DateTimeImmutable {
         $end = $periodEnd;
@@ -561,12 +673,18 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
             $end = $asOfDate;
         }
 
-        // Cap at contract end date if the employee has left.
-        $contractEndRaw = $employee->getCurrentContractEndDate();
-        if (null !== $end && null !== $contractEndRaw && '' !== trim($contractEndRaw)) {
-            $contractEnd = $this->parseYmdDate($contractEndRaw);
-            if ($contractEnd instanceof DateTimeImmutable && $contractEnd < $end) {
-                $end = $contractEnd;
+        // Closed phase: cap taken-absence accounting at the phase end.
+        if (!$phase->isCurrent && null !== $phase->endDate && $phase->endDate < $end) {
+            $end = $phase->endDate;
+        }
+
+        if ($phase->isCurrent) {
+            $contractEndRaw = $employee->getCurrentContractEndDate();
+            if (null !== $end && null !== $contractEndRaw && '' !== trim($contractEndRaw)) {
+                $contractEnd = $this->parseYmdDate($contractEndRaw);
+                if ($contractEnd instanceof DateTimeImmutable && $contractEnd < $end) {
+                    $end = $contractEnd;
+                }
             }
         }
 
@@ -584,9 +702,9 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
      *   splitSaturdays: bool
      * }
      */
-    private function resolveLeavePolicy(Employee $employee, DateTimeImmutable $from, DateTimeImmutable $to): ?array
+    private function resolveLeavePolicy(Employee $employee, ContractPhase $phase, DateTimeImmutable $from, DateTimeImmutable $to): ?array
     {
-        $type = $employee->getContract()?->getType();
+        $type = $phase->contractType;
         if (ContractType::FORFAIT === $type) {
             // Business days for forfait must use the RAW holiday list (excluded holidays like
             // "Lundi de Pentecôte" / journée de solidarité still count as non-working days for
@@ -615,12 +733,13 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
             ];
         }
 
-        $nature = ContractNature::tryFrom($employee->getCurrentContractNature());
+        // Resolve nature from the period defining the phase (use the phase's first period).
+        $nature = $this->resolveNatureForPhase($employee, $phase);
         if (ContractNature::CDI !== $nature && ContractNature::CDD !== $nature) {
             return null;
         }
 
-        $weeklyHours = $employee->getContract()?->getWeeklyHours();
+        $weeklyHours = $phase->weeklyHours;
         if (4 === $weeklyHours) {
             return [
                 'ruleCode'                => LeaveRuleCode::CDI_CDD_NON_FORFAIT->value,
@@ -815,19 +934,29 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
     /**
      * @return array{DateTimeImmutable, DateTimeImmutable}
      */
-    private function resolvePeriodBounds(Employee $employee, int $year): array
+    private function resolvePeriodBounds(Employee $employee, int $year, ContractPhase $phase): array
     {
-        if (ContractType::FORFAIT === $employee->getContract()?->getType()) {
-            return $this->resolveForfaitYearBounds($employee, $year);
+        if (ContractType::FORFAIT === $phase->contractType) {
+            [$from, $to] = $this->resolveForfaitYearBounds($employee, $year, $phase);
+        } else {
+            [$from, $to] = $this->resolveLeavePeriodBounds($year, $phase);
         }
 
-        return $this->resolveLeavePeriodBounds($year);
+        // Cap to the phase boundaries (applies to both modes).
+        if ($phase->startDate > $from) {
+            $from = $phase->startDate;
+        }
+        if (null !== $phase->endDate && $phase->endDate < $to) {
+            $to = $phase->endDate;
+        }
+
+        return [$from, $to];
     }
 
     /**
      * @return array{DateTimeImmutable, DateTimeImmutable}
      */
-    private function resolveLeavePeriodBounds(int $leaveYear): array
+    private function resolveLeavePeriodBounds(int $leaveYear, ContractPhase $phase): array
     {
         // Exercice CP "2026" = du 1er juin 2025 au 31 mai 2026.
         $from = new DateTimeImmutable(sprintf('%d-06-01 00:00:00', $leaveYear - 1));
@@ -839,24 +968,29 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
     /**
      * @return array{DateTimeImmutable, DateTimeImmutable}
      */
-    private function resolveForfaitYearBounds(Employee $employee, int $year): array
+    private function resolveForfaitYearBounds(Employee $employee, int $year, ContractPhase $phase): array
     {
         $from = new DateTimeImmutable(sprintf('%d-01-01 00:00:00', $year));
         $to   = new DateTimeImmutable(sprintf('%d-12-31 00:00:00', $year));
 
-        $contractStartRaw = $employee->getCurrentContractStartDate();
-        if (null !== $contractStartRaw && '' !== trim($contractStartRaw)) {
-            $contractStart = $this->parseYmdDate($contractStartRaw);
-            if ($contractStart instanceof DateTimeImmutable && $contractStart > $from) {
-                $from = $contractStart;
+        // When viewing the current phase, prefer the live "current contract" dates
+        // for backward compat with existing tests/usage. Closed phases rely on the
+        // generic cap applied in resolvePeriodBounds().
+        if ($phase->isCurrent) {
+            $contractStartRaw = $employee->getCurrentContractStartDate();
+            if (null !== $contractStartRaw && '' !== trim($contractStartRaw)) {
+                $contractStart = $this->parseYmdDate($contractStartRaw);
+                if ($contractStart instanceof DateTimeImmutable && $contractStart > $from) {
+                    $from = $contractStart;
+                }
             }
-        }
 
-        $contractEndRaw = $employee->getCurrentContractEndDate();
-        if (null !== $contractEndRaw && '' !== trim($contractEndRaw)) {
-            $contractEnd = $this->parseYmdDate($contractEndRaw);
-            if ($contractEnd instanceof DateTimeImmutable && $contractEnd < $to) {
-                $to = $contractEnd;
+            $contractEndRaw = $employee->getCurrentContractEndDate();
+            if (null !== $contractEndRaw && '' !== trim($contractEndRaw)) {
+                $contractEnd = $this->parseYmdDate($contractEndRaw);
+                if ($contractEnd instanceof DateTimeImmutable && $contractEnd < $to) {
+                    $to = $contractEnd;
+                }
             }
         }
 
@@ -878,16 +1012,23 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
         return $month >= 6 ? $year + 1 : $year;
     }
 
-    private function resolveFirstComputationYear(Employee $employee): int
+    private function resolveFirstComputationYear(Employee $employee, ContractPhase $phase): int
     {
-        $isForfait    = ContractType::FORFAIT === $employee->getContract()?->getType();
+        $isForfait    = ContractType::FORFAIT === $phase->contractType;
         $fallbackYear = $isForfait
             ? (int) new DateTimeImmutable('today')->format('Y')
             : $this->resolveCurrentLeaveYear(new DateTimeImmutable('today'));
 
+        // Do not go before the exercice containing $phase->startDate.
+        $phaseFirstYear = $isForfait
+            ? (int) $phase->startDate->format('Y')
+            : ((int) $phase->startDate->format('n') >= 6
+                ? (int) $phase->startDate->format('Y') + 1
+                : (int) $phase->startDate->format('Y'));
+
         $history = $employee->getContractHistory();
         if ([] === $history) {
-            return $fallbackYear;
+            return max($phaseFirstYear, $fallbackYear);
         }
 
         $oldestStartDate = null;
@@ -903,8 +1044,9 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
 
         if (null === $oldestStartDate) {
             $oldestBalanceYear = $this->leaveBalanceRepository->findEarliestYearForEmployee($employee);
+            $candidate         = null === $oldestBalanceYear ? $fallbackYear : min($fallbackYear, $oldestBalanceYear);
 
-            return null === $oldestBalanceYear ? $fallbackYear : min($fallbackYear, $oldestBalanceYear);
+            return max($phaseFirstYear, $candidate);
         }
 
         $firstYear = $isForfait
@@ -915,10 +1057,23 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
 
         $oldestBalanceYear = $this->leaveBalanceRepository->findEarliestYearForEmployee($employee);
         if (null !== $oldestBalanceYear && $oldestBalanceYear < $firstYear) {
-            return $oldestBalanceYear;
+            $firstYear = $oldestBalanceYear;
         }
 
-        return $firstYear;
+        return max($phaseFirstYear, $firstYear);
+    }
+
+    private function resolveNatureForPhase(Employee $employee, ContractPhase $phase): ?ContractNature
+    {
+        // Find the period at the start of the phase to determine its nature.
+        foreach ($employee->getContractPeriods() as $period) {
+            if ((int) $period->getId() === $phase->id) {
+                return $period->getContractNatureEnum();
+            }
+        }
+
+        // Fallback: nature of the current period (legacy behavior).
+        return ContractNature::tryFrom($employee->getCurrentContractNature());
     }
 
     private function parseYmdDate(string $value): ?DateTimeImmutable
diff --git a/tests/State/EmployeeLeaveSummaryProviderTest.php b/tests/State/EmployeeLeaveSummaryProviderTest.php
index 34fc8d7..f26583b 100644
--- a/tests/State/EmployeeLeaveSummaryProviderTest.php
+++ b/tests/State/EmployeeLeaveSummaryProviderTest.php
@@ -4,16 +4,32 @@ declare(strict_types=1);
 
 namespace App\Tests\State;
 
+use App\Dto\Contracts\ContractPhase;
+use App\Entity\Contract;
+use App\Entity\Employee;
+use App\Entity\EmployeeContractPeriod;
+use App\Enum\ContractNature;
+use App\Enum\ContractType;
+use App\Enum\TrackingMode;
+use App\Service\Contracts\EmployeeContractPhaseResolver;
 use App\State\EmployeeLeaveSummaryProvider;
 use DateTimeImmutable;
 use PHPUnit\Framework\TestCase;
 use ReflectionClass;
+use ReflectionProperty;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\RequestStack;
+use Symfony\Component\HttpKernel\Exception\UnprocessableEntityHttpException;
 
 /**
  * @internal
  */
 final class EmployeeLeaveSummaryProviderTest extends TestCase
 {
+    // -----------------------------------------------------------------------
+    // Existing tests (unchanged) — verify accrual prorating arithmetic.
+    // -----------------------------------------------------------------------
+
     public function testComputeAccruedDaysFromStartProratesPartialFirstMonth(): void
     {
         $provider = new ReflectionClass(EmployeeLeaveSummaryProvider::class)->newInstanceWithoutConstructor();
@@ -68,4 +84,253 @@ final class EmployeeLeaveSummaryProviderTest extends TestCase
 
         self::assertEqualsWithDelta(25.0 / 12.0, $result, 0.0001);
     }
+
+    // -----------------------------------------------------------------------
+    // Phase resolution tests (Task 3 — phaseId support).
+    // The repository / service dependencies are typed against final classes
+    // which PHPUnit cannot double, so phase resolution is exercised via
+    // reflection on private methods to avoid instantiating the full DI graph.
+    // -----------------------------------------------------------------------
+
+    public function testResolveTargetPhasePicksH39PhaseFromPhaseId(): void
+    {
+        $employee = $this->buildEmployeeWithTransition('2020-06-01', '2026-04-30', '2026-05-01');
+        $phases   = new EmployeeContractPhaseResolver()->resolvePhases($employee);
+        $h39Phase = $phases[1]; // oldest = 39h
+
+        $provider = $this->buildProvider(['phaseId' => (string) $h39Phase->id]);
+        $resolved = $this->invokePrivate($provider, 'resolveTargetPhase', $employee);
+
+        self::assertInstanceOf(ContractPhase::class, $resolved);
+        self::assertSame($h39Phase->id, $resolved->id);
+        self::assertSame(ContractType::H39, $resolved->contractType);
+        self::assertFalse($resolved->isCurrent);
+    }
+
+    public function testResolveTargetPhaseDefaultsToCurrentPhaseWhenPhaseIdAbsent(): void
+    {
+        $employee     = $this->buildEmployeeWithTransition('2020-06-01', '2026-04-30', '2026-05-01');
+        $phases       = new EmployeeContractPhaseResolver()->resolvePhases($employee);
+        $currentPhase = $phases[0]; // most recent = FORFAIT
+
+        $provider = $this->buildProvider([]);
+        $resolved = $this->invokePrivate($provider, 'resolveTargetPhase', $employee);
+
+        self::assertSame($currentPhase->id, $resolved->id);
+        self::assertSame(ContractType::FORFAIT, $resolved->contractType);
+        self::assertTrue($resolved->isCurrent);
+    }
+
+    public function testPastH39PhaseAppliesNonForfaitRuleCodeEvenWhenCurrentIsForfait(): void
+    {
+        // Verifies resolveLeavePolicy uses the phase's contractType (not the current contract).
+        $employee = $this->buildEmployeeWithTransition('2020-06-01', '2026-04-30', '2026-05-01');
+        $phases   = new EmployeeContractPhaseResolver()->resolvePhases($employee);
+        $h39Phase = $phases[1];
+
+        $provider    = $this->buildProvider(['phaseId' => (string) $h39Phase->id]);
+        $from        = new DateTimeImmutable('2025-06-01');
+        $to          = new DateTimeImmutable('2026-04-30');
+        $leavePolicy = $this->invokePrivate($provider, 'resolveLeavePolicy', $employee, $h39Phase, $from, $to);
+
+        self::assertNotNull($leavePolicy);
+        self::assertSame('CDI_CDD_NON_FORFAIT', $leavePolicy['ruleCode']);
+        self::assertSame(25.0, $leavePolicy['acquiredDays']);
+        self::assertEqualsWithDelta(25.0 / 12.0, $leavePolicy['accrualPerMonth'], 0.0001);
+    }
+
+    public function testResolvePeriodBoundsCapsAtPhaseEndDate(): void
+    {
+        // 39h phase (June 2020 → April 30 2026). Exercise 2026 spans June 2025 → May 31 2026.
+        // The phase cap should clip the upper bound to April 30 2026.
+        $employee = $this->buildEmployeeWithTransition('2020-06-01', '2026-04-30', '2026-05-01');
+        $phases   = new EmployeeContractPhaseResolver()->resolvePhases($employee);
+        $h39Phase = $phases[1];
+
+        $provider    = $this->buildProvider(['phaseId' => (string) $h39Phase->id, 'year' => '2026']);
+        [$from, $to] = $this->invokePrivate($provider, 'resolvePeriodBounds', $employee, 2026, $h39Phase);
+
+        self::assertSame('2025-06-01', $from->format('Y-m-d'));
+        self::assertSame('2026-04-30', $to->format('Y-m-d'));
+    }
+
+    public function testTransitionExerciseOnH39PhaseAccruesAround22Point9Days(): void
+    {
+        // 11 full months of accrual at 25/12 ≈ 22.917 days.
+        $employee = $this->buildEmployeeWithTransition('2020-06-01', '2026-04-30', '2026-05-01');
+        $phases   = new EmployeeContractPhaseResolver()->resolvePhases($employee);
+        $h39Phase = $phases[1];
+
+        $provider = $this->buildProvider(['phaseId' => (string) $h39Phase->id, 'year' => '2026']);
+        $method   = new ReflectionClass(EmployeeLeaveSummaryProvider::class)->getMethod('computeAccruedDaysFromStart');
+
+        // Period bounds for exercise 2026 on H39 phase = June 1 2025 → April 30 2026.
+        [$from, $to] = $this->invokePrivate($provider, 'resolvePeriodBounds', $employee, 2026, $h39Phase);
+        $acquired    = $method->invoke($provider, 25.0, 25.0 / 12.0, $from, $to);
+
+        self::assertEqualsWithDelta(22.92, $acquired, 0.1);
+    }
+
+    public function testYearOutsidePhaseRangeIsSilentlyClampedToPhaseLastExercise(): void
+    {
+        $employee = $this->buildEmployeeWithTransition('2020-06-01', '2026-04-30', '2026-05-01');
+        $phases   = new EmployeeContractPhaseResolver()->resolvePhases($employee);
+        $h39Phase = $phases[1];
+
+        $provider = $this->buildProvider(['phaseId' => (string) $h39Phase->id, 'year' => '2030']);
+        $year     = $this->invokePrivate($provider, 'resolveYear', $employee, $h39Phase);
+
+        self::assertSame(2026, $year);
+    }
+
+    public function testYearBeforePhaseIsClampedToPhaseFirstExercise(): void
+    {
+        $employee = $this->buildEmployeeWithTransition('2020-06-01', '2026-04-30', '2026-05-01');
+        $phases   = new EmployeeContractPhaseResolver()->resolvePhases($employee);
+        $h39Phase = $phases[1];
+
+        // Phase starts 2020-06-01 → first exercise (non-forfait) = 2021 (since month >=6 = year+1).
+        $provider = $this->buildProvider(['phaseId' => (string) $h39Phase->id, 'year' => '2010']);
+        $year     = $this->invokePrivate($provider, 'resolveYear', $employee, $h39Phase);
+
+        self::assertSame(2021, $year);
+    }
+
+    public function testInvalidPhaseIdReturns422(): void
+    {
+        $employee = $this->buildEmployeeWithTransition('2020-06-01', '2026-04-30', '2026-05-01');
+        $provider = $this->buildProvider(['phaseId' => '99999']);
+
+        $this->expectException(UnprocessableEntityHttpException::class);
+        $this->invokePrivate($provider, 'resolveTargetPhase', $employee);
+    }
+
+    public function testNonNumericPhaseIdReturns422(): void
+    {
+        $employee = $this->buildEmployeeWithTransition('2020-06-01', '2026-04-30', '2026-05-01');
+        $provider = $this->buildProvider(['phaseId' => 'abc']);
+
+        $this->expectException(UnprocessableEntityHttpException::class);
+        $this->invokePrivate($provider, 'resolveTargetPhase', $employee);
+    }
+
+    public function testDefaultYearForPhaseIdOnClosedPhaseUsesPhaseEndDate(): void
+    {
+        // No `year` param + explicit phaseId → default year is derived from $phase->endDate.
+        // H39 phase ends 2026-04-30 → non-forfait exercise containing that date = 2026.
+        $employee = $this->buildEmployeeWithTransition('2020-06-01', '2026-04-30', '2026-05-01');
+        $phases   = new EmployeeContractPhaseResolver()->resolvePhases($employee);
+        $h39Phase = $phases[1];
+
+        $provider = $this->buildProvider(['phaseId' => (string) $h39Phase->id]);
+        $year     = $this->invokePrivate($provider, 'resolveYear', $employee, $h39Phase);
+
+        self::assertSame(2026, $year);
+    }
+
+    public function testNoQueryParamsKeepsLegacyYearDefaulting(): void
+    {
+        $employee     = $this->buildEmployeeWithTransition('2020-06-01', '2026-04-30', '2026-05-01');
+        $phases       = new EmployeeContractPhaseResolver()->resolvePhases($employee);
+        $currentPhase = $phases[0];
+
+        $provider = $this->buildProvider([]);
+        $year     = $this->invokePrivate($provider, 'resolveYear', $employee, $currentPhase);
+
+        // Today is 2026-05-19, FORFAIT phase → year is the current calendar year (2026).
+        self::assertSame(2026, $year);
+    }
+
+    // -----------------------------------------------------------------------
+    // Test harness helpers.
+    // -----------------------------------------------------------------------
+
+    /**
+     * Build a two-period employee transitioning from H39 to FORFAIT.
+     */
+    private function buildEmployeeWithTransition(string $h39Start, string $h39End, string $forfaitStart): Employee
+    {
+        $employee = new Employee();
+        $this->setEntityId($employee, 1);
+
+        $h39Contract = new Contract();
+        $h39Contract->setName('39H');
+        $h39Contract->setTrackingMode(TrackingMode::TIME->value);
+        $h39Contract->setWeeklyHours(39);
+
+        $forfaitContract = new Contract();
+        $forfaitContract->setName('Forfait');
+        $forfaitContract->setTrackingMode(TrackingMode::PRESENCE->value);
+        $forfaitContract->setWeeklyHours(null);
+
+        $h39Period = new EmployeeContractPeriod();
+        $this->setEntityId($h39Period, 1);
+        $h39Period->setEmployee($employee);
+        $h39Period->setContract($h39Contract);
+        $h39Period->setStartDate(new DateTimeImmutable($h39Start));
+        $h39Period->setEndDate(new DateTimeImmutable($h39End));
+        $h39Period->setContractNature(ContractNature::CDI);
+        $h39Period->setIsDriver(false);
+
+        $forfaitPeriod = new EmployeeContractPeriod();
+        $this->setEntityId($forfaitPeriod, 2);
+        $forfaitPeriod->setEmployee($employee);
+        $forfaitPeriod->setContract($forfaitContract);
+        $forfaitPeriod->setStartDate(new DateTimeImmutable($forfaitStart));
+        $forfaitPeriod->setEndDate(null);
+        $forfaitPeriod->setContractNature(ContractNature::CDI);
+        $forfaitPeriod->setIsDriver(false);
+
+        $employee->getContractPeriods()->add($h39Period);
+        $employee->getContractPeriods()->add($forfaitPeriod);
+
+        return $employee;
+    }
+
+    /**
+     * Build an uninitialized provider with a RequestStack pre-loaded with the given query.
+     *
+     * The provider's repository/service dependencies are typed against final classes
+     * (EmployeeRepository, LeaveBalanceComputationService, etc.) which PHPUnit cannot
+     * double. We bypass full instantiation by using newInstanceWithoutConstructor and
+     * only setting the properties that the tested private methods actually read:
+     * `requestStack` and `phaseResolver`. Tests targeting heavier code paths exercise
+     * private methods directly (resolveTargetPhase, resolvePeriodBounds, etc.).
+     *
+     * @param array<string, string> $request query parameters (year, phaseId, ...)
+     */
+    private function buildProvider(array $request = []): EmployeeLeaveSummaryProvider
+    {
+        $requestStack = new RequestStack();
+        $requestStack->push(new Request(query: $request));
+
+        $reflection = new ReflectionClass(EmployeeLeaveSummaryProvider::class);
+        $provider   = $reflection->newInstanceWithoutConstructor();
+
+        $this->setReadonlyProperty($provider, 'requestStack', $requestStack);
+        $this->setReadonlyProperty($provider, 'phaseResolver', new EmployeeContractPhaseResolver());
+        $this->setReadonlyProperty($provider, 'dataStartDate', null);
+
+        return $provider;
+    }
+
+    private function invokePrivate(object $obj, string $method, mixed ...$args): mixed
+    {
+        $reflection = new ReflectionClass($obj::class);
+        $m          = $reflection->getMethod($method);
+
+        return $m->invoke($obj, ...$args);
+    }
+
+    private function setReadonlyProperty(object $obj, string $property, mixed $value): void
+    {
+        $reflection = new ReflectionProperty($obj::class, $property);
+        $reflection->setValue($obj, $value);
+    }
+
+    private function setEntityId(object $entity, int $id): void
+    {
+        $reflection = new ReflectionProperty($entity::class, 'id');
+        $reflection->setValue($entity, $id);
+    }
 }