[ctoth]

Propstore's ordinary-family merge currently compares only the two parent trees: a deleted stance returns from an unchanged peer, and a one-sided edit is rejected. Add the generic storage operation needed to compare exact base/left/right path versions before application-owned family transport.

iter_merged_tree_entries propagates one-sided additions, modifications and deletions, converges equal current object IDs, and raises TreeMergeConflict with exact path/base/parent witnesses for incompatible changes. It enumerates lazily and leaves final path/tree admission with the existing publisher. The implementation has no family or application semantics.

The archive-relative classification follows Khanna, Kunal and Pierce, A Formal Investigation of Diff3, pp.3,5, specialized to exact keyed Git paths. Equal object convergence is the requested storage equality contract; this does not implement Diff3's textual list alignment.

Validation: the new focused file passes26 cases covering symmetric path states, lazy conflicts, real Git history/object witnesses, write-free conflict refusal, and existing tree-prefix admission. The coupled Propstore regression reproduces18 failures before the repair and passes28 cases after path selection plus contributing-occurrence transport.

Supports propstore/propstore#174 and propstore/propstore#303. This draft is one bounded slice; the existing merge requirements remain tracked there.