A wildcard option can be marked as the fallback. It never takes part in a
normal draw and is used only when constraints (an Only rule included), a
filter or zero weights leave nothing else to pick, instead of resolving to
an empty string. Works for top-level wildcards and nested @{} refs, and
emits an info-level `fallback_used` note in place of
`constraint_excludes_all_options`.
- engine: engine/modules/_fallback.py shared by the handler and
ref_option_pool; payload validation allows one boolean fallback on a
non-null option
- schema 9 (additive): FALLBACK_SCHEMA_VERSION stamped in TS and Python,
MAX_KNOWN_SCHEMA_VERSION 9, strict validator keeps the flag, parity
fixture regenerated
- library editor: "set as fallback" on an option's probability cell, a
fallback chip, its weight disabled and excluded from the shares
- canvas: FALLBACK badge on the option row, no share in probabilities
- WP Debug: "Fallback used" label and step fact
- docs, release note, CLAUDE.md
- bundle budget raised 420 -> 424 KB (maintainer approved)
A derivation branch (and its ELSE) now runs its action and then each
entry of an optional extra_actions list, in order; each action sees the
previous one's write. The library editor gets "+ And" rows, the canvas
modal shows every action and gives each its own value override (keyed
"bi.K" / "else.K"), and WP Debug lists every action a branch ran.
$name.neg / $name.K.neg reads the negatives a variable carries. It rides
the accessor grammar's axis slot, so "neg" is reserved as an accepts
group name. Reading .neg is not a read of the variable, so it carries no
negatives along. Works in values, combines, the Assembler's negative
template and conditions; autocomplete offers it after the dot.
Both stamp schema v8. Cascade fixers and scans now walk the real
derivation action shape (action, extra_actions, else) instead of a stale
"actions" list, and read-only previews keep a var chip's accessor.
MAX_KNOWN_SCHEMA_VERSION goes to 8 with a content stamp for any non-empty
`negative` or an "Add to negative" derivation action, mirrored in the
Python exporter. The strict validators keep the new fields, the parity
fixtures carry one of each, and the payload types learn the field and the
`negative` derivation mode.
An accepts axis rolls one tag per pick (read as $var.AXIS), but a constraint
sourced from it folded over the option's whole menu instead of that rolled tag,
so $outfit.SHOES and the constrained $shoes could disagree. The source now
sends only the rolled winner; a target accepts axis OR-folds so a multi-tag
option survives when any alternative is allowed, then its own roll is pinned to
the allowed tag -- $source.AXIS == $target.AXIS under a diagonal. Classify
groups are unchanged (multiply).
The assembler also rendered $var.AXIS empty: __wp_axes__ crosses the socket on
ContextPayload.internals but the node only merged the internal-flag map; it now
merges the whole carve-out so the accessor resolves.
Import: the community validators silently dropped tag_group_kinds (and the
constraint target_select) because the lenient payload object never listed them,
degrading a shared accepts axis to classify. Both are now in the v2/v1
validators + the engine-parity fixtures, with preservation tests. Engine math
mirrored in TS via the shared corpus.
The community TS validators re-implement the engine's payload shapes by
hand, and drifted repeatedly (fixed_values entries-vs-values, wildcard
is_null omitted) -- each drift surfaced as a publish failure for a user.
This makes the engine the single source of truth.
- scripts/dump_engine_shapes.py: builds one sample payload per module
subtype, validates each against that subtype's own engine
Handler.validate_payload (raises if not engine-valid), and writes the
engine-row shape to src/validators/fixtures/engine-parity/*.json. Run
it whenever an engine module shape changes; commit the regenerated
fixtures.
- src/validators/__tests__/engine-parity.test.ts: asserts the STRICT
community validator accepts every engine-dumped fixture. 5/5 pass.
Now drift fails CI on either side: a sample that no longer matches its
handler fails the generator; a validator that rejects the real shape
fails the parity test. CLAUDE.md schema section documents the loop.
Claude