﴿وَكَانَ وَرَاءَهُمْ مَلِكٌ يَأْخُذُ كُلَّ سَفِينَةٍ غَصْبًا﴾
Behind them was a king who seized every ship by force. (Al-Kahf 18:79)
The context concerns vessels the king would want to seize: serviceable or intact ships. One rhetorical reconstruction supplies an implicit quality, as in kulla safīnatin ṣaḥīḥatin, “every sound ship.” The earlier intentional damage to the vessel indicates why such a qualification matters.
The reconstruction is a contextual explanation, not a claim that those added words occur in the Qur'anic text.
The preceding damage is thus an earlier contextual clue to the qualification.