In the aftermath of major promotional festivals, sustaining consumer engagement becomes a pressing challenge for livestream e-commerce platforms. This paper investigates how platforms and Key Opinion Leaders (KOLs) strategically coordinate marketing efforts to develop high-performing livestream products in post-promotional contexts. We construct a game-theoretic framework that models the strategic interaction between a platform and a KOL under three distinct collaboration structures: platform-led, KOL-led, and simultaneous decision-making. Our analysis yields three key findings. First, a structural transition in effort allocation emerges as the KOL's commission rate increases – from platform-only investment to bilateral cooperation, and ultimately to KOL-only investment – characterised by a commission–price threshold function. Second, contrary to conventional intuition, assigning leadership to the less efficient party can mitigate underinvestment and enhance joint performance, revealing a novel form of first-mover advantage. Third, while bilateral coordination can generate the highest demand growth, such cooperative outcomes are difficult to sustain when product prices are low. These insights advance the literature by integrating traffic allocation and endorsement effort into a unified analytical model and offer actionable implications for platform managers on how to design incentives and delegate decision rights to KOLs with varying marketing efficiencies.
Liang et al. (Sun,) studied this question.