High resolution absorption and emission line spectroscopy in the soft x-ray band are promising techniques to measure hot baryon distributions in extended galaxy halos, galaxy clusters, and the connecting filaments of the cosmic web. It can characterize outflows from supermassive black holes and help understand their impact on the structure and evolution of the interstellar medium and beyond. Stellar magnetic activity, accretion, coronal emission and flares are additional targets for soft x-ray spectroscopy. Higher resolving power and larger effective area than those provided by current missions are required in order to make progress. Recent breakthroughs in x-ray diffraction grating and mirror technologies promise order-of-magnitude improved performance if new missions were built today, and even greater improvements beyond the next decade. Here we describe recent progress in critical-angle transmission (CAT) grating technology. CAT gratings combine the advantages of traditional transmission gratings (relaxed alignment tolerances, low mass, transparency at higher energies) and blazed reflection gratings (high diffraction efficiency, high resolving power R due to blazing into high orders). CAT gratings have demonstrated resolving power greater than 10,000 and absolute diffraction efficiency above 30% in the soft x-ray band. They are an enabling technology for the Arcus grating spectrometer Explorer (R < 2500, effective area < 250 cm2) and a candidate for the Lynx x-ray grating spectrometer (R < 5000, effective area < 4,000 cm2).