fix(parser): parse external entry tap-state grammar

[matthewevans]

Rescues closed contributor PR #4991 for Vigorous Farming.

Parses the general external-entry tap-state grammar through the replacement pipeline and adds parser plus runtime coverage. Rebased onto current main and hardened after maintainer review.

Summary by CodeRabbit

• Bug Fixes

  • Improved recognition of effects that cause permanents to enter the battlefield tapped or untapped.
  • Supports both singular and plural wording, optional “the battlefield” phrasing, and more varied subjects.
  • Correctly handles replacement-effect ordering when multiple land-entry effects apply, ensuring the selected order produces the expected result.

• Tests

  • Added coverage for long-form untapped-entry text and real gameplay scenarios involving competing replacement effects.

[coderabbitai]

📝 Walkthrough

Walkthrough

The parser now supports long-form singular and plural untapped battlefield-entry text through one grammar helper. Parser tests and a Vigorous Farming integration test validate classification, replacement ordering, and the final untapped land entry.

Changes

External-entry replacement parsing

Layer / File(s)	Summary
External-entry grammar and classification crates/engine/src/parser/oracle_classifier.rs, crates/engine/src/parser/oracle_replacement.rs	The classifier recognizes singular and plural “enter the battlefield untapped” text. A shared helper parses subjects, verb number, optional battlefield wording, and tap state. Parser tests cover typed land and opponent-controlled Or-filter subjects.
Replacement pipeline validation crates/engine/src/parser/oracle_tests.rs, crates/engine/tests/integration/issue_4991_vigorous_farming.rs, crates/engine/tests/integration/main.rs	Tests verify the self-reference untap replacement, replacement ordering, and final untapped land entry. The integration module is registered in the test suite.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Possibly related PRs

• phase-rs/phase#6780: Both changes modify replacement-effect parsing in oracle_replacement.rs, but they cover different grammar cases.

Suggested reviewers: jacobwoodson

Sequence Diagram(s)

sequenceDiagram
  participant OracleClassifier
  participant ExternalEntryParser
  participant ReplacementPipeline
  participant ReplacementChoice
  OracleClassifier->>ExternalEntryParser: parse untapped battlefield-entry text
  ExternalEntryParser->>ReplacementPipeline: produce replacement definition
  ReplacementPipeline->>ReplacementChoice: present replacement ordering
  ReplacementChoice-->>ReplacementPipeline: apply self-tap replacement first
  ReplacementPipeline-->>ReplacementChoice: land enters untapped

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🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the parser fix for external-entry tap-state grammar.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch maintainer/rescue-4991-vigorous-farming

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@crates/engine/src/parser/oracle_classifier.rs`:
- Around line 736-737: Update is_replacement_pattern to return false before
scanning the long-form patterns when has_trigger_prefix(lower) is true,
preventing triggered abilities from matching these replacement phrases. Add
regression coverage for both “enter” and “enters” forms while preserving
replacement classification for non-triggered text.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: b1be679d-2218-4133-956c-84117048aba6

📥 Commits

Reviewing files that changed from the base of the PR and between b902333 and 968d571.

📒 Files selected for processing (5)

• crates/engine/src/parser/oracle_classifier.rs
• crates/engine/src/parser/oracle_replacement.rs
• crates/engine/src/parser/oracle_tests.rs
• crates/engine/tests/integration/issue_4991_vigorous_farming.rs
• crates/engine/tests/integration/main.rs

[coderabbitai]

🎯 Functional Correctness | 🟠 Major | ⚡ Quick win

Exclude triggered abilities from the new long-form classifier patterns.

is_replacement_pattern returns true for Whenever a land enters the battlefield untapped, .... The external-entry suffix parser requires end-of-input, so it cannot parse the trigger body after the comma. The classifier can send this triggered ability to replacement parsing instead of trigger parsing.

If has_trigger_prefix(lower) is true for either long-form phrase, return false before this pattern scan. Add regression coverage for both enter and enters forms.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@crates/engine/src/parser/oracle_classifier.rs` around lines 736 - 737, Update
is_replacement_pattern to return false before scanning the long-form patterns
when has_trigger_prefix(lower) is true, preventing triggered abilities from
matching these replacement phrases. Add regression coverage for both “enter” and
“enters” forms while preserving replacement classification for non-triggered
text.

[github-actions]

Parse changes introduced by this PR · 1 card(s), 2 signature(s) (baseline: main b9023330ef4b)

🟢 Added (1 signature)

• 1 card · ➕ replacement/ChangeZone · added: ChangeZone (scope=you control land, to zone=battlefield)
  • Affected (first 3): Vigorous Farming

🔴 Removed (1 signature)

• 1 card · ➖ ability/unknown · removed: unknown
  • Affected (first 3): Vigorous Farming