# Module 10 reference engine (Rust)

The course's own engine as of the end of Module 10: Part I's card engine and Part II's grid engine, joined by SpellGrid. Every test from Modules 1–9 still passes. Module 9's reference was the starting point, so a diff between the two shows what this module adds.

- `cards/` and `levels/` (at the crate root; not in this directory): copies of `course/cards/` plus `course/10-spellgrid/cards/` (SpellGrid's own cards, which only Module 10 on receives), and of `course/10-spellgrid/levels/`, staged by `tools/verify-references.mjs`.
- `src/engine/spellgrid.rs` (new): the only module that uses both engines. `SpellGrid` keeps a `World` and a `puzzle::Level` in step through the three seams: `rule_auras` (rules in force → auras), `CardSide::destroy` (hazard victims → one `Destroy` Sequence → the Death Creation Step), and `CardSide::sequence` (after each Sequence: write `TextSpawned` text, take dead minions off the grid, reparse). It also keeps one id space: a minion's id is its grid object's id.
- Part I (`src/engine/`, outside `puzzle/`):
  - `queue.rs`: `END_OF_PHASE` (`[DeathCreation, AuraUpdate]`) is the list of steps at the end of the outermost Phase, read from the world. `Action::SpawnText` records a `TextSpawned` event.
  - `world.rs`: `set_rule_auras`/`rule_auras` (auras that no minion carries), `set_end_of_phase`/`end_of_phase`, `entity_count`.
  - `aura.rs`: an Aura Update adds the rule auras for both players; `activations` applies an `Aura::TriggerCap`.
  - `card.rs`: `Aura::TriggerCap` (not in the card format: only SpellGrid makes it), and `CardDef::noun`.
  - `effect.rs`: `spawnText` is an action, not a panic. `event.rs`: `TextSpawned`.
- Part II (`src/engine/puzzle/`):
  - `level.rs`: `Destroy` and `remove_all`. `step_with` and `move_you_with` take a destroy function, which movement, conversion (`X IS NOT X`) and hazards hand their victims to; `step` and `move_you` pass `remove_all`. `reparse` and `board_mut` are public.
  - `grid.rs`: `Board::reserve_id`, and `cards`/`hand` in `LevelDef` (read only by SpellGrid), with `LevelCard`.
- `src/content/seams.json` and `seams()` (new): which nouns name a trigger (`DEATHRATTLE`) and which properties multiply one (`DOUBLE`, twice, `stacking: "max"`). `words.json` adds the SpellGrid nouns, `DEATHRATTLE` and `DOUBLE`.
- `src/harness.rs`: Module 10 adds `new_spell_grid` and `SpellGrid`, including the test hook `with_naive_aura_timing()`, which reverses `END_OF_PHASE` for one game.
- `src/cli.rs` and `src/bin/spellgrid.rs` (new): the command line, `cargo run --bin spellgrid -- levels/l1-double-tap.json` from a staged workspace (it needs `cards/` and `levels/`). `w a s d` move, `c <card> [x y]` casts a spell (at the minion on that tile) or plays a minion (onto that empty tile), `q` quits. `tests/cli.rs` plays it from a script; it is the reference's own check, not a course test.

Run it with the module's tests: `node tools/verify-references.mjs 10` from the course repository.