GameCult/CultLib
Watch
9
0
Fork
You've already forked CultLib
 0
Code Issues Pull requests 4 Projects Releases Packages Wiki Activity Actions 2

union-parity README: what every runtime walks for a read-only payload

Browse source 
Per vector: the object carrying the extra slot, its depth and the mark (type, slots carried, slots
declared); the counting rule (highest key + 1, short arrays and retired gaps do not mark, a union adds no
depth); the store-record assertions, the consent rule and the extra-slot-store.cc carry check that
cut-slot-readonly-ts/-py/-rs assert.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
Libby 2026-11-11 23:58:11 +00:00
commit 4e9820de6f
1 changed files with 48 additions and 23 deletions
Download patch file Download diff file Expand all files Collapse all files

63
tests/vectors/union-parity/README.md
View file

@ -48,29 +48,54 @@ with one part replaced.
## Extra trailing slot (outcome `read-only`)
Each payload is `union-surface.msgpack` with one slot appended past the reader's last declared slot of one
record (ruling `cultlib-gaps:ruling:extra-trailing-slots`: the record is read, read-only at any depth, every write
of it refused). A reader decodes the value of `union-surface.msgpack` from each; `detail` says where the slot is.
Rulings `cultlib-gaps:ruling:extra-trailing-slots` and `cultlib-gaps:ruling:slot-mark-consent`: a payload carrying a
slot past its reader's declared slots, in any object at any depth, is read, held read-only, and every write or
removal of it is refused before anything is staged. The first four payloads are `union-surface.msgpack` with the
string `"extra-slot"` appended as one more slot of one object; a reader decodes the value of `union-surface.msgpack`
from each. The fifth is a bare arm of union `UnitOutcome` (0 Waiting `[Message]`; 2 Denied2, -2147483648 Floor2 and
2147483647 Ceiling2, each `[]`), the union of the `unit-arm-*` files; a reader decodes Denied2 from it.
| File | detail | Record with the extra slot |
|---|---|---|
| `extra-slot-record.msgpack` | record | the document (slot 7) |
| `extra-slot-nested-record.msgpack` | nested-record | Composition `comp` |
| `extra-slot-arm.msgpack` | arm | the Root Box arm |
| `extra-slot-list-element.msgpack` | list-element | Text `s1`, an element of Use.Slots |
| `extra-slot-unit-arm.msgpack` | unit-arm | not a UnionSurface: a bare UnitOutcome arm `[2, [extra]]` where Denied2 declares no slot (union `UnitOutcome`, key 2) |
An object's declared slots are its highest key plus one. Only an array longer than that marks: a short array
(missing trailing slots) keeps the defaults and is writable, and a non-nil value in a retired slot below the highest
key (Image's slot 2) does not mark. A union adds no depth: an arm's array is counted against the arm's own slots.
`depth-skipped-at-limit.msgpack` (bounds file) is also `read-only`: its extra slot is a deeply nested value at depth 0.
Five rows of `outcomes.msgpack` are `read-only` (record, nested-record, arm, list-element, unit-arm).
| File | detail | Object with the extra slot | Depth | Mark: type, slots carried, slots declared |
|---|---|---|---|---|
| `extra-slot-record.msgpack` | record | the document (slot 7) | 0 | UnionSurface, 8, 7 |
| `extra-slot-nested-record.msgpack` | nested-record | Composition `comp` | nested | Composition, 3, 2 |
| `extra-slot-arm.msgpack` | arm | the Root Box arm | nested | Box, 3, 2 |
| `extra-slot-list-element.msgpack` | list-element | Text `s1`, an element of Use.Slots | nested | Text, 3, 2 |
| `extra-slot-unit-arm.msgpack` | unit-arm | Denied2 in `[2, ["extra-slot"]]` (union `UnitOutcome`, key 2) | as placed | Denied2, 1, 0 |
| `depth-skipped-at-limit.msgpack` (bounds file) | depth | the document (slot 7, a value of nested arrays) | 0 | UnionSurface, 8, 7 |
`extra-slot-store.cc` is a single-file store holding two records of `tests.union_surface`: `marked` (the
`extra-slot-nested-record.msgpack` payload) and `clean` (the ordinary value); the store's clock is pinned to
2026-01-01T00:00:00Z as `union-surface.cc`'s.
Each payload marks exactly one object. Five rows of `outcomes.msgpack` are `read-only` (record, nested-record, arm,
list-element, unit-arm); the sixth `read-only` payload is in `bounds-outcomes.msgpack`. The payload nesting check
runs before the mark: `depth-skipped-past-limit.msgpack` is refused, never marked.
Every runtime asserts the same for a `read-only` payload loaded as a store record: the value is read past the extra
slot, the record reports the unread slots (the first type read with them, the slots it carried and the slots the
reader declares) and is not writable, and a write or removal of it is refused before anything is staged. Opening
`extra-slot-store.cc` and writing `clean` leaves `marked` byte for byte, with its schema id and its catalog entry.
### What a runtime asserts for a `read-only` payload
Load it as a store record under the reader's own schema id (the C# reference puts each UnionSurface payload in a
`tests.union_surface` store; the unit arm goes in slot 1 of a document `[Name, Outcome: UnitOutcome]`). Then:
1. the value is read past the extra slot;
2. the record reports the mark as in the table: the first type read with extra slots, the slots it carried and the
slots the reader declares, and the count of objects that carried extra slots (1 here);
3. the record is not writable (C#: `CultCache.IsWritable(key)` false), and a key no store holds is writable;
4. a replacing write, a variant write and a removal of the key (and a flatten, when the marked record is a variant)
are refused before anything is staged,
with the runtime's schema conflict refusal carrying the mark; its message names the type and both counts and
never contains `extra-slot`, the slot's value;
5. a write to another key of the same store succeeds.
Consent: a mark is explained only when it is at depth 0 and the schema comparison of the record's stored id against
the reader reported ignored extra slots, i.e. the record is stored under an id the reader lists compatible and the
catalog entry for that id has more members. Declaring that id consents to an explained mark only. Every mark in the
table is unexplained (stored under the reader's own id), so each record stays read-only whatever is declared.
`extra-slot-store.cc` is a single-file store of two `tests.union_surface` records, the store's clock pinned to
2026-01-01T00:00:00Z as `union-surface.cc`'s: `marked`, whose payload is `extra-slot-nested-record.msgpack`, and
`clean`, the value of `union-surface.msgpack`. Open it, assert `marked` read-only and `clean` writable, write `clean`
and flush: `marked`'s payload bytes, schema id and stored-at, and every catalog entry's bytes, equal the originals.
## Bounds (`bounds-outcomes.msgpack`)