This study examines how linguistic scaffolding, collaborative writing, and feedback operate as interconnected pedagogical mechanisms in task-based Arabic writing instruction. It reports a focused qualitative classroom-process analysis embedded within a broader research-and-development study conducted at an Islamic boarding school in Bogor, Indonesia. The analysis centered on 14 male upper-secondary students who participated in a ten-period task-based writing program. Data were obtained from classroom observations, interviews, instructional documents, classroom writing activities, and implementation records, and were analyzed thematically by tracing patterns of linguistic support, peer interaction, feedback engagement, and revision. The findings show that linguistic scaffolding helped learners access vocabulary, structures, and task expectations before writing; collaborative work enabled them to generate ideas, compare expressions, and negotiate linguistic choices; and teacher and peer feedback directed attention to unresolved problems that were subsequently addressed through revision. These mechanisms operated sequentially and recursively rather than independently. The study contributes a process-oriented explanation linking linguistic scaffolding, collaborative meaning-making, feedback and noticing, revision, and meaningful Arabic writing. The findings imply that effective task-based writing requires coordinated support across the writing process rather than the assignment of communicative tasks alone.