Measure auto-width children intrinsically, constrain them to resolved tracks, account for border-box wrapper content, and align every rendered line before painting the wrapper border.
Measure every rendered line when a column determines its natural width so a narrower first Grid line cannot cause later lines to overflow after stack padding.\n\nVerified with make check; core 545/545 and Grid 11/11 passed.
Split the verified renderer, layout engine, Grid support, native boundary, tests, examples, and paired documentation into the independent Ebox repository. Keep ETAF and application concerns outside this package.
