Add Valakut Fireboar: switch its power and toughness (pronoun form)

[e11734937-beep]

Summary

Adds engine support for Valakut Fireboar (ZEN) — "Whenever this creature attacks, switch its power and toughness until end of turn." — by teaching the effect parser the pronoun surface form "switch its power and toughness".

Effect::SwitchPT and its layer-7d runtime already exist (Invert, Inversion Behemoth are the supported siblings). The parser recognized two surface forms — prepositional "switch the power and toughness of <target>" and possessive "switch <target>'s power and toughness" — but not the bare pronoun "switch its power and toughness". parse_target does not treat a bare "its" as a target, so both branches missed it and the trigger effect fell to Effect::Unimplemented; the P/T swap never fired.

The fix adds a third branch that matches "switch its power and toughness" and resolves the "its" anaphor through the shared resolve_it_pronoun(ctx) helper — the same anaphor resolution already used by the sacrifice/counter clauses. For Valakut Fireboar the trigger subject is this creature, so "its" resolves to SelfRef (the source switches its own P/T). The change is generic: any effect written as "switch its power and toughness" now lowers to Effect::SwitchPT.

Files changed

• crates/engine/src/parser/oracle_effect/imperative.rs — pronoun branch in the SwitchPT parser
• crates/engine/src/parser/oracle_effect/tests.rs — parser unit test effect_switch_pt_pronoun_its
• crates/engine/tests/valakut_fireboar_switch_pt_on_attack.rs — integration test

Anchored on

• crates/engine/src/parser/oracle_effect/imperative.rs (~4516) — the existing prepositional and possessive SwitchPT branches; this adds the pronoun sibling immediately before the possessive one.
• crates/engine/src/parser/oracle_effect/mod.rs:172 — resolve_it_pronoun already maps "it/its" to SelfRef or TriggeringSource from ctx.subject; reused verbatim.
• crates/engine/src/game/effects/switch_pt.rs — Effect::SwitchPT runtime (layer-7d SwitchPowerToughness); unchanged. Invert and Inversion Behemoth exercise this handler today.

CR references

• CR 613.4d — switching a creature's power and toughness is a single continuous effect applied in layer 7d.
• CR 608.2c — the triggered ability's instruction resolves as written; "its" refers to the object established by the trigger (here, the attacking creature).

Track

Developer

LLM

Model: claude-opus-4-8
Thinking: high

Verification

• cargo fmt --all — clean
• cargo clippy-strict — clean (0 warnings)
• ./scripts/check-parser-combinators.sh — clean
• cargo test -p engine — full engine suite green, 0 failed across all binaries (adds effect_switch_pt_pronoun_its + valakut_fireboar_switches_power_and_toughness_when_it_attacks)
• ./scripts/gen-card-data.sh — Valakut Fireboar: 0 Unimplemented entries
• Coverage regression (clean main baseline vs this change, scripts/coverage-regression-check.sh --fail-on-engine): supported 31223 → 31224 (net +1). GAINED: Valakut Fireboar. REGRESSED (engine): 0. REGRESSED (coverage honesty): 0. ORACLE CHANGED: 0. (Invert / Inversion Behemoth unchanged.)
• cargo semantic-audit — Valakut Fireboar: 0 findings.

The integration test drives the real declare-attackers → trigger → stack → resolution pipeline: Valakut Fireboar (printed 5/2) is declared as an attacker; after the trigger resolves, its effective power/toughness must be 2/5. It flips if the parser branch is reverted — the trigger effect becomes Unimplemented and the P/T stays 5/2.

Scope Expansion

None. (Mangled Soulrager's granted "twelve-time boon" also uses this phrasing, and its "switch its" orphan is now closed; but that card's boon-granting mechanic is a separate unsupported infra gap, so it stays gap_count 1 and is out of scope here.)

Validation Failures

None.

CI Failures

None.

[gemini-code-assist]

Code Review

This pull request adds support for parsing the pronoun form "switch its power and toughness" (with optional "until end of turn" duration) in the MTG engine's imperative oracle effect parser, resolving "its" via the shared it-pronoun anaphor. It also introduces an integration test for Valakut Fireboar to verify this behavior during combat. There are no review comments, and I have no feedback to provide.

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[github-actions]

Parse changes introduced by this PR · 1 card(s), 2 signature(s) (baseline: main e9cb2001ec8c)

1 card(s) · ability/SwitchPT · added: SwitchPT (duration=until end of turn)

Examples: Valakut Fireboar

1 card(s) · ability/switch · removed: switch (duration=until end of turn)

Examples: Valakut Fireboar

2 card(s) had Oracle-text changes (errata/reprint) — excluded as non-parser.

[matthewevans]

Reviewed current head: scoped SwitchPT pronoun parser fix, matching parse-diff evidence for Valakut Fireboar only, green checks, and discriminating runtime coverage.