Tracking: standardize expression types across schema, Ruby, and UIs #11

Tracking issue for enforcing expression types from a single source of truth (this schema repo), spanning three repos. Lives here because expressions is the root dependency and lowest-traffic repo.

Goal

• Q1: enforce flipper_properties value types (scalars only).
• Q2: enforce operator argument types via the JSON Schema, shared by Ruby + JS.
• Standardize on flippercloud/expressions as the source of truth; Ruby vendors the schemas, the Vue UIs import the JS package.

Merge / publish order (hard dependency chain)

① expressions (merge + npm publish) → ② flipper → ③ Vue UIs. Nothing downstream can land until the package is published.

① expressions (this repo)

• Commit the schema work — added FeatureEnabled.schema.json, category metadata. (Note: the property definition was dropped during review since it described context values, not expressions.)
• Push, open PR, review, merge — Add FeatureEnabled expression, schema metadata, and publish under @flippercloud scope #10 (MERGED).
• Package renamed @flippercloud.io/expressions → @flippercloud/expressions, version bumped to 1.1.0 on main.
• Publish npm @flippercloud/expressions@1.1.0 ← still pending; this unblocks everything below (npm currently 404s for the new name).

② flipper — PR flippercloud/flipper#1000 (green, ready)

• Vendored schemas into lib/flipper/expression/schemas (no npm); Flipper::Expression::Schema + #validate/#valid? backed by an optional, lazily-required json_schemer (core stays lightweight; validation runs at the boundaries, not on the evaluate hot path or in enable).
• Q1 property enforcement in Gates::Expression (warn + drop non-scalar values; uses a Ruby ALLOWED_PROPERTY_TYPES constant, so unaffected by the dropped property definition).
• Operator parity: added Add/Subtract/Multiply/Divide/Min/Max, restored Duration (enables relative-time windows, e.g. Now < Time(signup_at) + Duration(7, "days")).
• Shared example test runs the vendored examples/*.json so Ruby and JS test the same cases; rake expressions:vendor re-copies schemas + examples.
• Re-vendored to match merged main (dropped property def). Vendored schemas now identical to the source of truth.
• After ①.publish: optional version bump + CHANGELOG; merge #1000.

③ Vue UIs — flippercloud + flipper-pro (not started; needs its own workspace)

• Add @flippercloud/expressions dependency (note the renamed scope).
• Derive operators + constraints from the schema in Condition.vue / templates.js instead of hardcoding.
• Validate client-side before save.
• Add operators the UIs are missing (FeatureEnabled, flippercloud).

Decisions locked in

• json_schemer optional (its dep bigdecimal is a C extension); validation at the UI/API boundaries, not core enable.
• In/NotIn deferred until implemented end-to-end (referenced only in flippercloud's display-only ExpressionDescriber; not evaluable in Ruby today).
• Duration kept; full arithmetic family kept and tested; per-operator Ruby specs kept alongside the shared suite.
• Property values are scalar-only (string/number/boolean/null), enforced in Ruby via ALLOWED_PROPERTY_TYPES; arrays gated behind a future In/NotIn.