Agent Skills: Implement a Card

MANDATORY PREPARATION

Before doing any substantive work, run ./.agents/skills/cyberpunk-tcg-rules (or ./.codex/skills/cyberpunk-tcg-rules) and keep its glossary in context for the full task. Load the matching reference files for every mechanic the card touches.

Implement a Card

• CARD_TYPE = one of legends, units, programs, gear
• CARD_FILE = the card's file stem (e.g. v-corporate-exile, jackie-welles-pour-one-out-for-me)

Step 1 — Load context

1. Run the cyberpunk-tcg-rules skill and keep the full glossary in context.
2. Read the relevant reference files for every mechanic the card uses:
   • references/turn-structure.md — setup, phases, overtime
   • references/combat-and-gigs.md — Gigs, Street Cred, attacking, blocking
   • references/cards-and-keywords.md — card types, keywords, triggers
3. Then read:
   • packages/cards/src/alpha/{CARD_TYPE}/{CARD_FILE}.ts — abilities, keywords, costs, power
   • packages/engine/src/alpha/{CARD_TYPE}/{CARD_FILE}.test.ts — scaffold to fill in
   • A reference implementation of the same card type (see table below)

| CARD_TYPE | Canonical reference test | | ---------- | ----------------------------------------------------------------------- | | legends | packages/engine/src/alpha/legends/goro-takemura-hands-unclean.test.ts | | units | Nearest existing unit test with a similar ability shape | | programs | Nearest existing program test with a similar ability shape | | gear | Nearest existing gear test with a similar ability shape |

Step 2 — Understand the card

From the definition file, identify every ability and classify it:

| Type | What to look for | | --------------------------------- | ------------------------------------------------------------------------------ | | Card type | legend, unit, program, gear — governs zones, timing, and fixture setup | | Power | Present on Legends and Units; absent on Programs; on Gear it buffs the host | | Keywords | GO SOLO, BLOCKER → rules from the skill (Legends and Units only) | | Triggered abilities | trigger event, firstTimeEachTurn limits, effects | | Static abilities | kind: "static", duration, conditions, targets, value; no trigger | | Classifications | e.g. Arasaka, Merc → may affect other cards' abilities | | Attachment target (Gear only) | Which units or legends this Gear can attach to |

Let card text override base rules wherever they conflict.

Step 3 — Identify what engine support exists

Before writing a single test, grep for each ability's trigger/effect type in the engine to confirm it is already implemented. If it is not, implement the engine behaviour first, then write tests.

Places to check:

• packages/engine/src/moves/ — move-level hooks
• packages/engine/src/operations/ — effect primitives
• packages/engine/src/types/game-events.ts — existing event types
• packages/engine/src/ability-executor.ts — generic event-trigger pipeline (handles firstTimeEachTurn limits, binding resolution, optional effects, conditional effects); hooked into play-card.ts after the cardPlayed event

Known engine patterns and gaps

• Event-typed triggers (cardPlayed, gigStolen, etc.) are processed by ability-executor.ts. The processEventTriggers(...) call must exist in the relevant move handler — it is currently hooked into play-card.ts, call-legend.ts, attack-unit.ts, attack-rival.ts, and resolve-attack.ts. If a new event type needs triggering from a different move, add the call there.
• flip triggers require legendFlipped processing: call-legend.ts calls processEventTriggers for both legendFlipped (fires flip triggers) and legendCalled (fires call triggers) events, in that order. If a legend has a flip trigger, the legendFlipped event processing is what activates it — not legendCalled.
• DSL event name vs. engine event type: Card definitions use DSL event names (e.g. cardAttacks) that differ from engine GameEvent types (e.g. attackDeclared). The mapping lives in EVENT_TYPE_TO_DSL in triggers/index.ts. Direct triggers (call, flip, defeated) are matched directly by matchTriggers in triggers/index.ts via the targeted pass (switch cases). When adding new event-based triggers, add entries to these maps.
• defeated trigger (cardDefeated event): resolve-attack.ts emits cardDefeated AND calls processEventTriggers immediately after. passesEventFilter returns true for non-"event" triggers (play, attack, etc.) so they pass through after matchTriggers pre-selects them.
• Bindings must be satisfied before costs are paid: processEventTriggers skips any ability whose required bindings return no targets. Effects are also pre-checked for targets before costs are paid. This prevents unwanted spending when there is no valid target.
• ability.costs is processed by processEventTriggers: Spend costs are validated (card not already spent) and paid before executing effects.
• firstTimeEachTurn limit tracking lives in TurnMetadata.abilityFiredThisTurn[]; it is cleared by resetTurnFlags at turn end.
• evaluateCondition for targetValue: { value: "max" } compares the die's face value against DIE_MAX_VALUES[die.dieType] (the die type's structural maximum, not the current game-wide max).
• handleModifyGig clamps the result to [1, DIE_MAX_VALUES[dieType]].
• playCard effect from triggered abilities: Creates a chooseCardToPlay pending choice. Resolve it with engine.resolveCardToPlay(gear). The bound attachTo target is resolved eagerly and stored as resolvedAttachToId in the pending choice payload. New move resolveCardToPlay handles the resolution.
• hasAttachedCards: false target filter: The engine correctly handles this to find cards with NO attached gear. Used in bindings for "equip to unit with no gear" abilities.
• activated trigger (spend abilities): Cards with trigger: { trigger: "activated" } and costs: [{ cost: "spend" }] are spend-activated abilities. These are NOT handled by processEventTriggers — they require the activateAbility move (packages/engine/src/moves/activate-ability.ts). The move validates the card is face-up (for legends), can pay costs, then executes the ability's effects. Test with engine.activateAbility(card, abilityIndex).
• searchDeck effect: Creates a searchDeck pending choice. Resolve it with engine.resolveSearchDeck(selectedCards) (pass an array of card refs to add to hand, or [] to select nothing). The move validates selected cards match the target filter (card type, classifications, maxCost) and are within the look window. Non-selected cards are bottom-decked. The resolveSearchDeck move lives in packages/engine/src/moves/resolve-search-deck.ts.
• Deck fixture for search tests: Use deck: 20 to ensure enough cards remain after the 6-card opening draw. Use engine.patchState() or engine.judgeMoveCardToTopOfDeck() to position specific cards at the top of the deck before activating search abilities.
• getLastActionLog() may not return the expected log when a flip trigger fires searchDeck: The callLegend → flip trigger → searchDeck pipeline emits multiple action logs (move.callLegend, then move.searchDeck.reveal). Use engine.getEvents("actionLog") and filter by messageKey instead of relying on getLastActionLog() for the call log.
• gigStolen event triggers: resolve-attack.ts now calls processEventTriggers for each gigStolen event after gig stealing. The event carries sourceCardId (the attacker). passesEventFilter handles gigStolen with player (friendly/rival based on toPlayerId) and source: { selector: "self" } (matches event.sourceCardId against the ability card's instanceId). The moveGig operation accepts an optional sourceCardId parameter.
• ifYouDo + removeFromGame with optional: true: When removeFromGame is the doEffect inside ifYouDo and has optional: true, the engine auto-executes it (removes the card). The optional flag does not create a player confirmation choice — it auto-resolves. The ifEffects then fire (e.g. playCard from trash).
• Direct attack resolution requires 3 resolveAttack calls: The flow is: (1) resolveAttack() (P1, offensive → defensive), (2) resolveAttack({ as: P2, pass: true }) (P2, defensive → resolve), (3) resolveAttack() (P1, resolve: execute steal/fight).
• cardAttacks trigger target filter (classifications, cardTypes): passesEventFilter checks the target property on cardAttacks triggers, filtering by target.cardTypes and target.classifications against the attacking card's definition. This ensures triggers like "when a friendly Arasaka unit attacks" only fire for matching units.
• discardFromHand effect: Creates a chooseTarget pending choice (with payload.type: "discardFromHand") when amount > 1 or hand has more cards than the amount. In the current engine behavior, this means a pending choice is still created when hand.length === amount and amount > 1; it only auto-resolves when there is no actual selection to make (for example, a single-card discard with exactly one card in hand). Resolve the pending choice with engine.resolveDiscardFromHand(cards). The move lives in packages/engine/src/moves/resolve-discard-from-hand.ts.
• Conditional effects (effect.conditions): executeAbilityEffects evaluates effect.conditions before each effect. If any condition fails, the effect is skipped. For example, discardFromHand with a streetCred condition only fires when the player's Street Cred meets the threshold.

Static modifyPower continuous abilities (kind: "static", no trigger)

These are evaluated dynamically — they are NOT stored as continuousEffects.

1. Check packages/engine/src/static-effects/index.ts for computeStaticPowerModifier. If the function or the relevant branch is absent, implement it before writing tests.
2. Check packages/engine/src/moves/resolve-attack.ts — it historically had a local getEffectivePower copy. If it still does, remove it and import from static-effects/index.ts so attack resolution picks up the new modifier.
3. Static abilities do not emit events; skip the "Action log" scenario for pure static modifiers.

Per-target attacking condition in static abilities

The generic evaluateCondition("attacking") checks ids[0] (first resolved card), which is wrong for per-unit buffs like "Your Arasaka units have +1 power when attacking."

In computeStaticPowerModifier, special-case attacking: check attack.attackerId === cardId (the card whose power you're computing) instead of using the generic evaluator.

Do NOT change evaluateCondition itself — triggered abilities rely on the existing ids[0] semantics.

Step 4 — Write the tests

Replace the scaffold body. Structure the file as one describe block per keyword/ability, with the ability's full rules text as the describe label. Inside each block, cover:

| Scenario | What to assert | | ------------------- | ------------------------------------------------------------------------------------------------------------- | | Happy path | The effect fired, state changed correctly | | Side effects | Cards spent, counts changed, zones updated | | Negative path | expectFailure with the right errorCode | | Action log | getLastActionLog() has the right messageKey and params; formatActionLog produces readable output | | Power during attack | For static power modifiers: use toHaveEffectivePower to assert effective power when attacking and when idle |

Add at least 8 meaningful tests beyond the scaffold. Note the baseline test count before starting.

Fixture rules — by card type

Legend

• Default (triggered / flip abilities): legendArea: [legend] — card starts face-down; static abilities are INACTIVE; enters play via callLegend.
• To test a static ability without calling the legend first, use:

  legendArea: [{ card: legend, faceDown: false }];
  

  Omitting faceDown: false silently disables the ability — you will see base power.
• GO SOLO legends entering ready: field: [{ card: legend, spent: false, faceDown: false }] — no legendArea entry needed. The faceDown: false is critical: legends default to faceDown: true at creation time (based on initial zone), and the fixture only overrides faceDown when explicitly set. Without it, triggered abilities on a field legend will be silently inactive because collectFromAllCards skips face-down legends.
• Filler legends (auto-filled when legendArea < 3) start face-down and cannot silently activate static abilities — no need to exclude them explicitly.
• spent: true is overridden by skipSetup for legend area cards: the fixture engine resets all legend area cards to spent: false on setup. To test "legend is already spent" scenarios, use engine.patchState(draft => { ... draft.G.cardIndex[id].meta.spent = true; }) after creating the fixture.
• callLegend always costs 2 eddies: add eddies: 2 (or more) to any fixture that calls a legend.
• attackRival / attackUnit now fire cardAttacks triggers: legends and field units with trigger.trigger === "event" && event.event === "cardAttacks" will fire when any unit attacks (after the engine fixes in PR feat/implement-river-ward-detective-on-the-hunt).

Unit

• Play from hand (summoning sickness applies): hand: [unit], eddies: cost → call engine.playCard(unit).
• Pre-placed on field, ready (no summoning sickness): field: [{ card: unit, spent: false }].
• Pre-placed on field, spent: field: [{ card: unit, spent: true }].
• GO SOLO units: play via playCard(unit); they enter ready and can attack that turn.

Program

• Programs are one-shot. Place in hand, pay cost, play — the effect resolves immediately and the card goes to trash.
• hand: [program], eddies: cost → engine.playCard(program) → assert state change, then check card is in trash.
• Programs have no power; skip all power/attack assertions.

Gear

• Gear must be attached to a valid host. hand: [gear], eddies: cost + a target unit on the field → engine.attachGear(gear, targetUnit).
• When the host unit leaves the field, Gear moves to the same zone (assert this).
• Gear with a static power modifier buffs the host's effective power; test with toHaveEffectivePower on the host.

Cross-type fixture rules (apply to all)

• A card definition appears in at most one player's fixture; the engine deduplicates filler picks, but explicit placements must not overlap.
• gigArea entries: [{ dieType: "d6", faceValue: 3 }]. Standard fixer dice are one each: d4, d6, d8, d10, d12, d20. To create a sided-pair (two dice with the same face value), use two different die types with the same faceValue — e.g. [{ dieType: "d6", faceValue: 3 }, { dieType: "d8", faceValue: 3 }]. Using the same dieType twice will silently fail because only one die of each type exists in the fixer area.
• Filler legends are drawn from the full card catalog. Never assume a specific card is absent from the legend area unless you control all three slots.
• Eddies do not regenerate between turns. Set eddies high enough for all plays from the start (e.g. eddies: cost * 4).
• deck: N fixture draws N cards into the deck list, but createMatchState draws 6 cards to the opening hand. If you use deck: N to test a "trash from deck" or "count deck cards" effect, use at least deck: 20 (or larger) so that 14+ cards remain after the opening-hand draw. Using deck: 5 or fewer will leave the deck empty and the effect will silently no-op.
• To put a card in hand for a second turn, declare two copies at fixture time: hand: [card, card]; the second remains after the first is played.
• completeTurn() cannot be called while an attack is in progress. Resolve the attack first (via resolveAttack steps), then call passPhase() once (already in attack phase) instead of completeTurn() (which calls passPhase twice and fails because the second call is the opponent's turn).
• Attacking a ready rival unit returns error code TARGET_READY, not DEFENDER_NOT_SPENT. Use expect(failure.errorCode).toBe("TARGET_READY") in negative-path tests.

TestEngine conventions

| Convention | Detail | | ----------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | engine.passToAttackPhase() | Wraps passPhase(); advances from play to attack phase | | engine.getAttackState() | Safe accessor; never read engine.getState().G.attackState directly | | engine.getCard(card) | No zone/player args when the card is unique on the board. If the card catalog includes the same definition for deck filler, always pass zone and player — e.g. engine.getCard(card, "field", P1) — to avoid resolving to a different instance in the deck/hand | | engine.getLastActionLog() | Never write a local lastLog helper (N/A for static-only abilities) | | engine.getGigValue(playerId, dieIndex?) | Returns faceValue of the nth gig die (0-indexed) | | engine.getHandCount(playerId) | Returns number of cards in hand | | { as: P1 } | Omit — active player defaults to P1; only pass { as: P2 } when acting as P2 | | Reusable assertions | Belong on CyberpunkTestEngine as a method, not as a test-local function | | registerMatchers() | Must be called once at the top of any test file that uses toHaveEffectivePower or other custom matchers. Import from "../../testing/index.ts" | | toHaveEffectivePower | expect(engine.getState()).toHaveEffectivePower({ card: instance.instanceId as string, value: n }) — verify power with/without static modifier, before and during attack | | engine.resolveCardToPlay(gear) | Resolves a chooseCardToPlay pending choice by selecting the given gear card. Required after any ability that uses the playCard effect (e.g. River Ward's equip). | | engine.activateAbility(card, idx) | Activates a spend-activated ability on a card. idx is the 0-based ability index in the card's abilities array. Pays costs and executes effects. | | engine.resolveSearchDeck(cards) | Resolves a searchDeck pending choice. Pass an array of card refs to select (or [] to pick nothing). Selected cards go to hand; rest are bottom-decked. | | engine.resolveDiscardFromHand(cards) | Resolves a discardFromHand pending choice. Pass an array of card refs to discard from hand to trash. The number of cards must match the required discard amount. |

For static power modifiers, add a test proving idle units on the same field are NOT buffed (only the qualifying unit benefits).

When asserting "no effects" on a unit, filter by origin: "imperative" or specific kind/rule values. Units on the field carry static cantAttack (summoning sickness) active effects with origin: "static" — a raw activeEffects.some(e => e.targetCardId === id) check will always be true and the negative assertion will fail.

Step 5 — Run and iterate

source ~/.zshrc && vp test packages/engine --run

Fix failures. Do not move on until all tests pass. Confirm the new test count exceeds the pre-implementation baseline by at least 8.

Step 6 — Retrospective (self-update this skill)

Answer each question below. For any answer that reveals a new pattern, edge case, or constraint, edit this SKILL.md file directly to incorporate it. That is what creates the virtuous loop — each card either confirms existing patterns (prompt stays tight) or reveals a new constraint (prompt absorbs it so the next card starts with that knowledge already baked in).

Questions to answer:

1. Was any engine operation missing? → document the pattern for detecting this earlier (add to Step 3)
2. Did any fixture constraint cause a failing test that was surprising? → add a note to the matching card-type fixture section in Step 4
3. Was a new TestEngine helper needed? → add it to the conventions table
4. Did any rules question arise that the skill didn't answer? → note it so the cyberpunk-tcg-rules skill can be updated
5. Were any ActionLogMessageKey entries missing? → note the pattern for adding them
6. Was there a per-target condition (attacking, playedThisTurn, etc.) that needed special handling in computeStaticPowerModifier rather than the generic evaluateCondition? → document the pattern
7. Did a new card type reveal fixture patterns not yet covered in Step 4? → add a new card-type section

After editing, commit the updated SKILL.md with message: docs(skills): update implement-card playbook after {Card Display Name}.

Step 7 — Make a PR

• Branch: feat/implement-{CARD_FILE}
• Commit message: feat(engine): implement {Card Display Name}
• PR description must include:
  • Card type and which abilities are covered
  • Which engine operations were added or reused