Fix Witherbloom Affinity, Sprout Swarm convoke, Crafty Cutpurse

[AgilErck]

Summary

Three independent card-correctness fixes, each covering a class beyond the named card. Review-cycle corrections folded in (CR-annotation fixes + alt-ordering bug + spec.controller redirect under CR 111.2).

1. Witherbloom, the Balancer — Affinity display and granted-keyword parsing

• Display cost for un-castable spells. legal_actions_full only populated spell_costs for spells with an active CastSpell action, so a commander you couldn't yet afford fell back to the printed {5}{B}{G} instead of the Affinity-reduced cost. Added display_spell_cost, an engine-authoritative path that runs the full cost-modification pipeline (Affinity, ReduceCost/RaiseCost, commander tax, pending one-shot reductions) while suppressing situational checks (timing, mana, can't-cast statics). Threaded a for_display flag through prepare_spell_cast_with_variant_override_inner.
• Granted keyword parser. Keyword::from_str(\"affinity for creatures\") fell through to Keyword::Unknown(...), so the granted-keyword path on Witherbloom's static silently no-op'd at cast time (CR 702.41a). Added an \"affinity for \" prefix-strip branch routing through the same parse_affinity_type helper used by the colon-separated form.
• Affected filter scope. parse_spells_have_keyword collapsed compound type prefixes ("instant and sorcery") to TypedFilter::card(), broadening the granted keyword to every spell type — latent under bug chore: update coverage stats and badges #2, real otherwise. Resolved by using main's apply_spell_keyword_subject_constraints recursive helper, which preserves the TargetFilter::Or disjunction across both branches.

Class coverage: every "[type] spells you cast have [keyword]" card with a compound type prefix or a granted Affinity (Auriok Sunchaser-class artifact statics, Crucible-class graveyard land statics, etc.).

2. Sprout Swarm — Convoke creatures get the mana-tap ring

isManaObjectAction only matched TapLandForMana and Mana-typed ActivateAbility. During WaitingFor::ManaPayment { convoke_mode: Some(_) }, GameBoard's mana-tappable iteration skipped creatures because their actions didn't classify as mana, and PermanentCard's click handler gated dispatch on isActivatable || canTapForMana, both false for convoke creatures. Net effect: the convoke prompt appeared but no creature could be tapped.

Classified TapForConvoke as a mana action so the same code path that routes land taps now routes convoke (and waterbend) taps. Also added the missing TapForConvoke variant to the hand-maintained GameAction union in adapter/types.ts.

3. Crafty Cutpurse — Token controller redirect replacement

Pre-fix the trigger parsed as Effect::Unimplemented, so even though the replacement pipeline could express the redirect it never got installed and opponent-controlled token creation resolved normally (violating CR 111.2).

Three architectural pieces:

1. token_owner_redirect: Option<ControllerRef> on ReplacementDefinition. Pairs with the existing token_owner_scope: scope matches which CreateToken events fire, redirect rewrites the proposed owner on the modified event. You resolves to the source's controller; Opponent finds the first non-source-controller player (representable but not used by Magic). Threaded through create_token_applier so the shadowed owner flows into the final ApplyResult::Modified and into the Chatterfang-style additional_token_spec recursive event.
2. replacement_targets understands TargetFilter::SelfRef (CR 201.5), so the Crafty Cutpurse self-install can anchor the replacement on its own source without depending on having explicit targets.
3. Parser try_parse_token_controller_redirect recognizes "each token that would be created under control this turn is created under control instead" — built on nom combinators, accepts "each/any" + "an opponent's"/"your opponents'"/"your" on both sides, marks the replacement with expiry: Some(RestrictionExpiry::EndOfTurn) ("this turn").

Known limitation: the self-installed replacement lives on Cutpurse's replacement_definitions, which find_applicable_replacements only scans for Battlefield/Command zone objects. If Cutpurse leaves the battlefield mid-turn the redirect stops, which is technically incorrect ("this turn" should persist). A floating-replacement anchor would close that gap; out of scope here.

Review-cycle corrections folded in

• CR 111.6 → CR 111.2 across the six sites that cited the wrong rule. CR 111.2 is the rule the redirect actually overrides ("the token enters the battlefield under that player's control"); CR 111.6 is about tokens being subject to permanent-affecting effects.
• CR 109.5 → CR 201.5 for the SelfRef-anchoring comment in replacement_targets. CR 109.5 is about you/your pronoun resolution; CR 201.5 is the self-name reference rule.
• to_ctrl alt ordering: bare "your" was first, so "your opponents'" would match the 4-byte prefix and strand " opponents'" before the next tag. Mirrored from_ctrl's longer-prefix-first order.
• spec.controller follows redirected owner in create_token_applier. The apply path uses spec.controller (not owner) for combat::enter_attacking, so a redirected enters-attacking token (Goblin Rabblemaster class) would compute its defender against the original effect controller and end up attacking its new controller. Regression test exercises a tapped: true, enters_attacking: true Goblin under Cutpurse.

Verification

• cargo test -p engine --lib: 7194 / 7194 pass (1 ignored).
• cargo clippy --workspace --all-targets -- -D warnings: clean.
• cargo fmt --all --check: clean.
• Coverage regression vs main: 0 engine regressions, 0 coverage-honesty regressions; +2 cards gained (Crafty Cutpurse, Red Herring); swallowed-clause diagnostics down 1633 → 1624. 3 baseline-true flips are MTGJSON oracle-text rewordings (Fast, Very Cryptic Command, Artist Alley), not engine regressions.

Test plan

• CI: rust fmt + clippy + workspace tests
• CI: coverage-regression check vs preview baseline
• CI: frontend lint + type-check (note: pre-existing useTransitions TS gap on App.tsx unrelated to this branch)
• Manual: cast Witherbloom, the Balancer from the command zone, verify the Affinity-reduced cost is displayed on the commander card before mana is available
• Manual: cast Sprout Swarm with Convoke, verify creatures show the mana-tap ring and can be tapped for the convoke cost
• Manual: with Crafty Cutpurse on the battlefield, have an opponent cast Treasure-generating or Saproling-generating spells and verify the tokens enter under your control

🤖 Generated with Claude Code

[gemini-code-assist]

Code Review

This pull request introduces support for 'Affinity for [type]' cost reductions and 'Crafty Cutpurse' token redirection, refactoring the casting pipeline to provide display-ready costs and adding TargetFilter::SelfRef for replacements. Feedback highlights several style guide violations, including an R1 violation for using strip_prefix in parsing, an R2 violation for using a bool flag in casting logic, and an L1 violation regarding the Opponent redirect logic. The reviewer also noted duplicated castable zone logic and missing round-trip tests for the new TapForConvoke action.