fix(parser): bind perpetual cost grants to prior referents

[ntindle]

Summary

• Parse bound It perpetually gains "This spell costs ..." clauses as ApplyPerpetual cost modifiers when the effect chain already has a prior object referent.
• Keep standalone It perpetually gains ... honest-red instead of silently binding it to the source.
• Remove Bloodsprout Talisman, Geistchanneler, and Nightclub Bouncer from root cause chore: update coverage stats and badges #19 in docs/parser-misparse-backlog.md.

Root Cause

These Alchemy clauses were falling through to generic continuous-modification parsing. That produced GenericEffect entries with UntilEndOfTurn duration instead of persistent ApplyPerpetual cost modifications. The missing piece was the bound-pronoun subject form after a prior ChooseFromZone or targeted clause.

Card-Data Audit

Full raw card-data.json before/after exports both contained 35,397 cards. The only raw card entries that changed were:

• bloodsprout talisman: GenericEffect / UntilEndOfTurn / Any -> ApplyPerpetual / ParentTarget / ModifyCost Reduce {1}
• geistchanneler: GenericEffect / UntilEndOfTurn / Any -> ApplyPerpetual / ParentTarget / ModifyCost Reduce {2}
• nightclub bouncer: GenericEffect / UntilEndOfTurn / ParentTarget -> ApplyPerpetual / ParentTarget / ModifyCost Raise {2}

Related perpetual-cost cards that still require separate root-cause fixes, such as Chronicler of Worship, Garruk, Wrath of the Wilds, Lumbering Lightshield, and Thought Rattle, were intentionally unchanged.

coverage-parse-diff reports no parse_details changes because this PR changes the serialized effect shape rather than the coverage detail text.

Verification

• cargo fmt --all
• ./scripts/check-parser-combinators.sh
• RUSTC_WRAPPER= ZIG_GLOBAL_CACHE_DIR=/tmp/phase-zig-global-cache ZIG_LOCAL_CACHE_DIR=/tmp/phase-zig-local-cache cargo test -p engine --features cli --lib perpetual_modify_cost
• RUSTC_WRAPPER= ZIG_GLOBAL_CACHE_DIR=/tmp/phase-zig-global-cache ZIG_LOCAL_CACHE_DIR=/tmp/phase-zig-local-cache cargo clippy -p engine --all-targets -- -D warnings
• Full raw card-data audit against origin/main: changed exactly bloodsprout talisman, geistchanneler, and nightclub bouncer
• RUSTC_WRAPPER= ZIG_GLOBAL_CACHE_DIR=/tmp/phase-zig-global-cache ZIG_LOCAL_CACHE_DIR=/tmp/phase-zig-local-cache cargo run -p engine --features cli --bin card-data-validate -- /tmp/phase-root19-full/head/card-data.json
• RUSTC_WRAPPER= ZIG_GLOBAL_CACHE_DIR=/tmp/phase-zig-global-cache ZIG_LOCAL_CACHE_DIR=/tmp/phase-zig-local-cache cargo run -p engine --features cli --bin coverage-parse-diff -- /tmp/phase-root19-full/base/card-data.json /tmp/phase-root19-full/head/card-data.json --base-sha origin/main --markdown /tmp/phase-root19-full/coverage-parse-diff.md --json /tmp/phase-root19-full/coverage-parse-diff.json

[gemini-code-assist]

Code Review

This pull request updates the parser misparse backlog documentation (docs/parser-misparse-backlog.md) to reflect the resolution of several cards. Specifically, it decrements the total count of implicated cards and updates the 'Perpetual (Alchemy) duration mis-mapped to UntilEndOfTurn' backlog item by removing Bloodsprout Talisman, Geistchanneler, and Nightclub Bouncer from the list, reducing its count from 71 to 68. There are no review comments, and I have no feedback to provide.

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[github-actions]

Parse changes introduced by this PR · 3 card(s), 3 signature(s) (baseline: main 201c535f9d33)

3 card(s) · ability/ApplyPerpetual · added: ApplyPerpetual

Examples: Bloodsprout Talisman, Geistchanneler, Nightclub Bouncer

2 card(s) · ability/ReduceCost · removed: ReduceCost (affects=any target, duration=until end of turn, grants=ReduceCost, target=any target)

Examples: Bloodsprout Talisman, Geistchanneler

1 card(s) · ability/RaiseCost · removed: RaiseCost (affects=any target, duration=until end of turn, grants=RaiseCost, target=parent target)

Examples: Nightclub Bouncer

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

[matthewevans]

Holding review on this head because GitHub currently reports the branch as conflicting with main (mergeStateStatus: DIRTY, mergeable: CONFLICTING). The parse-diff evidence is present and checks are green, but I need the branch brought current/resolved before I can review the actual mergeable diff. Please rebase or merge main and push a new head; I will review it after the conflict is cleared.

[matthewevans]

Thanks for the update. I found one remaining behavior blocker, and the branch is also currently conflicting with main:

[MED] Empty ChooseFromZone paths can apply the perpetual cost grant to the source. Evidence: crates/engine/src/parser/oracle_effect/mod.rs:7216, crates/engine/src/game/effects/choose_from_zone.rs:79, and crates/engine/src/game/effects/perpetual.rs:104. Why it matters: Bloodsprout Talisman / Geistchanneler with no eligible card should do nothing, but the new ParentTarget sub-ability can resolve with no inherited targets and fall back to modifying the source. Suggested fix: make ApplyPerpetual { target: ParentTarget } no-op when no parent/choice/event object exists, and add a runtime empty-choice regression.

Also, current head is mergeable: CONFLICTING / mergeStateStatus: DIRTY; the conflict needs to be resolved before this can be considered for queueing.