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We consider a periodic quantum clock based on cooperative resonance fluorescence at zero temperature. In the quantum case, this system has an exact steady state and the limit cycle appears in conditional quantum dynamics under homodyne detection. We show that the intrinsic quantum phase diffusion on the limit cycle leads to fluctuations in the period. By simulating the stochastic master equation for homodyne detection, we extract the statistical properties of the clock period. We show that the precision of the clock satisfies the quantum-thermodynamic kinetic uncertainty relations. As energy dissipation increases, the clock quality improves, fully validating, in a quantum stochastic system, the link between energy dissipation and clock precision.