[Roxas2712]

Beat Up currently reuses ordinary damage for every healthy party member. Native GBA execution instead calculates each participant's level/species-base damage independently, then applies Helping Hand, a separate critical roll and variation. The six-member fixture must produce 3, 5, 7, 4, 9 and 6 rather than six copies of the active user's damage.

Add a dedicated native party executor and a per-hit damage seam. Read eligibility after accuracy and live between callbacks; retain owned PP once, continue after breaking Substitute, stop at fainting, and preserve the source's special/neutral/noncritical event metadata. Special counter memory keeps the last direct strike, including zero HP loss under Endure. Earlier-generation fallback remains separate.

Stacked on #203. Review feature commits ade8abd, 5538fa4 and 92ade2b relative to 8c7df4d. The composed canonical effect proof additionally requires #121.

Validation:

• 1,330/1,330 focused checks across FireRed/Emerald and all four user positions: mixed teams, live party filtering, levels/base stats, individual critical/variation rolls, Helping Hand, type/stat independence, interruption/miss/Protect, Substitute, fainting, Endure and callback mutations.
• Same actual API-3 consumer/fixture against clean read-only Gen1Recomp 535a5ec088c1ae1bf4d91dd3e35a56f64cf46d91: 40 isolated workers / 4,486 paired observations pass, including active target versus retained party species, and earlier enemy-action, target, Follow Me, Helping Hand and Spit Up contracts. A shared real content patch changes MEW's base Attack and the resulting native strikes.
• Negative control: unchanged Match native GBA Spit Up damage and Stockpile consumption #203 fails 168 assertions in the new FireRed cases. The Endure and active-target-species regressions each failed 16 assertions before their respective fixes.
• Full quick feature run on final production code: 88/97 engine suites versus 87/96 on clean Match native GBA Spit Up damage and Stockpile consumption #203. Exact Counters of all 25 inherited FAIL lines across nine suites match; no additions. SDK 3/3 and B30 pass.
• With Map portable move effects and secondary chances to native handlers #121 composed: 14/14 checks load a real mod, patch canonical EFFECT_BEAT_UP and species base stats, execute the selected move, and verify individual amounts, owned PP, last-strike memory and zero ordinary damage/critical callbacks.
• BEAT_UP_EFFECT revision 1 changes fixture digest 397df21576af62f1 to d518411055f17444. Only move_effects changes (c62807cde682a669 to f45a80ce5e45ef42); removing the revision restores the former digest.
• actionlint, scoped StyLua and git diff --check pass.

Both engines and the contract workflow use maintained JIT-enabled LuaJIT v2.1 commit a4c064539ea931274d407e1249b4bb575424a0f4. RNG observations normalize semantic critical/variation operands; no complete raw RNG-trace parity is claimed.

Synthetic imported-shaped rows and ordinary side parties are covered. Focus Band's native adjustment schedule, joined multi-trainer/link parties, intro/tutorial controllers, animations and complete gameplay remain separate acceptance surfaces. Gen1 is read-only; no Gen1 source modification or publication is required. Combined-fork acceptance and hosted CI are reported below.

Hosted CI for 92ade2b: all five workflows report action_required pending maintainer approval. The dedicated contract workflow has zero executed jobs. Local acceptance is separate.

Combined-fork acceptance: integrated into Roxas2712:codex/portability-testing, tested clean runtime f6f3bfe. All 215/215 engine suites, 3/3 SDK suites and B30 pass with zero FAIL lines. The same 40-worker / 4,486-observation comparison passes on that clean runtime, and the real canonical-effect mod proof passes 14/14. Integration preserves the existing fourth damage-adjustment argument, GBA Substitute counter guard and battle-scoped party fallback, and updates only the audited effect-section fingerprint pin. Subsequent combined commits only record validation.

Active-species cases seed the actual native battler fields separately from retained party species; they do not claim the full Transform animation/controller path.