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On GLVND Linux eglGetProcAddress returns a non-NULL trampoline for ANY name - including a fabricated one - so pointer-nullness can never signal driver support. The three EXT multi-draw entry points were registered as required (spurious error logs on drivers without them) and their pointers were trusted; the NVIDIA ES driver hands back a stub for glMultiDrawElementsBaseVertexEXT that SILENTLY DROPS draws, which once made a "77% faster" multi-draw batch that rendered nothing. The three entries are optional now, and two extension-derived capability flags follow the established Supports* pattern - each is an extension-string check AND a resolved pointer, so a flag alone is sufficient at a call site: SupportsMultiDrawIndirect: GL_EXT_multi_draw_indirect + both entry points resolved. SupportsMultiDrawElementsBaseVertex: (GL_EXT or GL_OES_draw_elements_base_vertex) + GL_EXT_multi_draw_arrays + the entry point resolved. The multi_draw_arrays conjunct is the registry fact the stub exploited: glMultiDrawElementsBaseVertexEXT exists only in interaction with GL_EXT_multi_draw_arrays, and this NVIDIA driver advertises everything else EXCEPT that one - so the entry point is genuinely unsupported while eglGetProcAddress still "resolves" it. Two DriverPost rows report both capabilities (INFO when absent - a fallback always exists). Unit tests pin the stub shape, the exact NVIDIA shape, the supported shape and extension-without-pointer. Proven load-bearing: forcing the old pointer-only condition on the NVIDIA ES driver reproduces the silent drop exactly (sodium retrace SSIM 1.000000 -> 0.329522, no crash, no GL error); with the gate the same run is a literal 1.000000. Unit suite 423/423 (two new tests), retrace subset 10/10, integration suite 52/52.