KCAE.SOURCE:4.4 - Implement and test the source return

A practical exact reader accepts a source edition and a locator, then returns the requested material, its structural envelope, continuation information and the edition actually served. A pagination cursor should bind the edition and requested unit. Expose an end marker or explicit remaining extent so that truncated output cannot masquerade as complete reading. Do not rely on a line number without its edition.

When a heading moves, a semantic document/section identity can help resolve the new location, but exact historical reading still selects the old edition. When a section splits or merges, preserve explicit predecessor/successor relations and inspect them before treating them as equivalent. A fuzzy match may suggest a new location; it cannot silently establish identity or preserve an earlier judgement.

Verify build, persist, reload, find and read on a fixture that includes additions, deletions and shifted headings. Check that the returned text corresponds to the selected source, that a deleted locator yields an explicit result and that a child unit expands through the correct note. Preserve the qualification result with the extraction/version where the installation needs it. KCAE.EVAL distinguishes this mechanical correctness from useful question answering.