refactor(parser): route Frozen-in-Ice replacement through IR lowering (05b tranche 2)

[matthewevans]

Plan 05b — Tranche 2: Frozen-in-Ice replacement → IR lowering

Routes the single try_split_and_cant_become_untapped replacement producer (Frozen-in-Ice
class) from the legacy DocEmitter::replacement_at through the IR path, via a new
ReplacementIr::from_definition(source_text, definition) seam and DocEmitter::replacement_ir_at.

Behavioral no-op: pure routing, no new parsing logic. replacement_ir_at emits only —
unlike static_at, replacement_at never maintained a last_* peek. execute_ir: None
mirrors StaticIr's body_ir: None (the untap-prevention replacement has no execute body).
The IR Replacement node is already a live lowered path (tranche 1's compound-static path
emits it), so this routes one more producer into a proven node type.

Correctness evidence

• Byte-identity: full-pool card-data.json regen is sha256-identical to baseline (b6c79b7a…).
• Snapshots: zero churn — no IR snapshot test covers this path.
• Gates: clippy -D warnings clean; engine lib 17,479 passed / 0 failed; integration 3,702 / 0.

Scope guard: the two out-of-scope replacement_at sites (drain_result_vectors, ETB) are
untouched — they belong to later tranches. Second of the 05b tranches feeding the Plan-05
gate-1 zero-hit ratchet.

Summary by CodeRabbit

• Bug Fixes
  • Improved parsing of continuous grants or restrictions that prevent permanents from becoming untapped.
  • Ensured replacement effects are consistently represented and applied during rules processing.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: f25dcba0-24c3-4392-9f1e-0bff0cef02fd

📥 Commits

Reviewing files that changed from the base of the PR and between 67dbf2d and 36d19d6.

📒 Files selected for processing (2)

• crates/engine/src/parser/oracle.rs
• crates/engine/src/parser/oracle_ir/replacement.rs

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📝 Walkthrough

Walkthrough

The Oracle parser adds a ReplacementIr constructor and a DocEmitter helper for direct replacement IR emission. The cross-layer “can’t become untapped” handling now uses this path with the current source line as context.

Changes

Oracle replacement IR emission

Layer / File(s)	Summary
Construct and emit replacement IR crates/engine/src/parser/oracle_ir/replacement.rs, crates/engine/src/parser/oracle.rs	ReplacementIr::from_definition wraps a replacement definition with source text and no effect-chain body; DocEmitter::replacement_ir_at emits it, and the untap-prevention parser path uses both helpers.

Estimated code review effort: 2 (Simple) | ~10 minutes

Suggested reviewers: carlos4s

🚥 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 accurately describes the routing of the Frozen-in-Ice replacement through IR lowering, which matches the main change.
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 ship/p05b-tranche-2-replacement-ir

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[github-actions]

Parse changes introduced by this PR

✓ No card-parse changes detected.