Assign retained TP identity before layout and emit pure, runtime-free surface plans with exact character and text-property equivalence. Keep live publication unchanged for the staged cutover and add focused surface, package, docs, and CI contracts.\n\nVerified: make check EMACS=/Applications/Emacs.app/Contents/MacOS/Emacs\nVerified: WERROR byte compilation for all 16 active Lisp files\nVerified: focused ebox-surface checkdoc has zero warnings
Render auto-width grid children at their resolved track widths before resolving row heights. This keeps wrapped content visible and prevents stale intrinsic heights from clipping the final line.
Verification: make grid-tests EMACS=/Applications/Emacs.app/Contents/MacOS/Emacs; make compile EMACS=/Applications/Emacs.app/Contents/MacOS/Emacs; make check EMACS=/Applications/Emacs.app/Contents/MacOS/Emacs.
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.
Keep the standalone Ebox package focused on its public layout and DSL primitives while the generic ebox-playground package owns executable .ebox references.
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.
