Order 20260827T123301Z-3790625395 asked for a judgement on a profile-named
`index.sort_key`, explicitly not for code. The finding is accepted and so is
the mechanism; the shape needs one correction.
Verified what the order asserts about us: Door C sorts its index on the
concept path and nothing else (`importer.py:421`, a plain `sorted(documents)`),
and no policy object anywhere in the chain can redirect it. `FacetPolicy`
governs what an entry CARRIES; nothing governs how entries are ARRANGED. A
consumer cannot reach this today, exactly as claimed.
The correction: naming a key is necessary and not sufficient, and the
insufficiency is where the requester's own measured gain lives. A sort needs a
key, a value and a COMPARATOR, and D5's formula seats only the first two.
Measured here: sorted() over N100.9/N100.10/N100.2/N100.20/N100.1/N99.1 puts
N100.10 before N100.2 and N99.1 after the whole N100 family. A `sort_key:
req_number` resolved through default ordering would therefore have produced a
different wrong order, not the 100.0% ascending over 24338 pairs that was
measured. The library already knows this one module over -- `_version_key`
(`structure.py:375`) exists for it and its comment says why.
So: three fields on `IndexPolicy`, not one on `FacetPolicy` -- `sort_key`,
`sort_order` from a closed set (`lexicographic` | `natural`, never a
caller-supplied callable, which would make emitted bytes depend on caller code
and break rebuild-equals-incremental), and `sort_missing`. Concept path stays
the final tie-break so the new ordering REFINES the existing total order rather
than replacing it; trading S8b determinism for retrieval quality would be the
worse failure.
Timing: build after the segmentation voyage lands, as a parameter on the
`_index_sort_key` seam Step 10 leaves behind, unifying both doors' index
writers in the same change. That seam is real and manifest-enforced, but it is
Door B's while this order is Door C's -- a profile naming an ordering that one
door honours and the other ignores would repeat the `IndexPolicy.per_directory`
trap.
Not claimed: that ordering explains the whole gap. T8-4 remains unexplained and
we attach no hypothesis to it either.
Order: 20260827T123301Z-3790625395-from-.claude
Co-Authored-By: Claude <claude-opus-5>
