filters values are case-sensitive and undocumented; an unmatched value returns an empty set instead of an error #265

Symptom

deck_list filters=[{type: card-type, mode: include, values: ["land"]}]  → 0 cards
deck_list filters=[{type: card-type, mode: include, values: ["Land"]}]  → 1 card (correct)

Lowercase "land" returns an empty result with no warning, indistinguishable from "this deck has no lands". Same applies to deck_curve.

Root cause

• packages/shared/src/filters/index.ts:52 — filter.values.includes(primaryType) is an exact string match against PrimaryType values (Creature, Land, …).
• color (line 46) compares against W/U/B/R/G/C exactly; ownership (line 60) compares against unknown/owned/need_to_buy exactly; cmc (line 41) uses includes on numbers, so a string "3" never matches.
• The tool schema in packages/mcp-server/src/tools/schemas.ts:14 declares values: { type: 'array', items: {} } — untyped, so nothing tells the caller what the legal values are.
• Nothing validates that a value matched anything.

Fix

1. Normalise case in matchesFilter (or in the MCP arg validator validateDeckListArgs / validateDeckCurveArgs in tools/types.ts) — lowercase both sides for card-type, color, ownership; coerce numeric strings for cmc.
2. Document the legal values per filter type in CARD_FILTER_SCHEMA (a oneOf per type, or at minimum the value lists in the description). PRIMARY_TYPES in packages/shared/src/types/index.ts is the source of truth for card-type.
3. Reject a filter value that is not in the legal set with an error naming the valid values, rather than returning an empty list.

Test

packages/shared/src/filters/index.test.ts (applyFilters) — "land", "LAND", and "Land" all match; "lnad" throws (or whatever the chosen behaviour is).