Growing research focuses on chiral quasibound states in the continuum (q-BICs) due to urgent needs in left-/right-circularly polarized (LCP/RCP) detection and absorption devices. Conventional chiral q-BICs suffer from quickly decaying quality factors (Q factors), making robust high-Q responses critical. Here, we present a planar chiral metasurface absorber with dynamically tunable chirality, enabled by a periodically arranged sixfold-symmetric double-skeleton-fan (DSF) structure and backed by a metallic mirror. Introducing gap perturbations folds guided modes above the light cone via Brillouin zone folding (BZF), creating robust high-Q BZF-BICs with topological singularities. Breaking in-plane ${\mathrm{C}}_2$ symmetry transforms BZF-BICs into high-Q q-BZF-BICs and generates a pair of C points, achieving strong extrinsic absorption circular dichroism (absorption $\mathrm{CD}=-0.96$, $Q>{10}^7$) and near-perfect RCP absorptance (0.997) verified by temporal coupled-mode theory. Breaking $z$ symmetry reveals a BZF-accidental BIC (BZF-A-BIC) on the guided resonance band, directly enabling high-Q intrinsic chiral absorptance (absorption $\mathrm{CD}=-0.87$, $Q>{10}^6$). Notably, we demonstrate dynamically tunable intrinsic chirality with sign reversal (absorption ${\mathrm{CD}}_{\text{max}}=0.91$ and tunable range ${\mathrm{\Delta }}_{\text{CD}}=1.78$) using phase-change material ${\mathrm{Sb}}_2{\mathrm{Se}}_3$, showcasing flexibility for chiral sensing, lasing, and imaging in future.

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• Fano resonance
• Metasurfaces
• Mie scattering
• Nanophotonics
• Near-field optics
• Optical interactions with surfaces
• Topological effects in photonic systems