Agent: intent, decision, state machine

#Intent (packages/agent/src/intent.ts)

Deterministic pt-BR parser. "quero um açaí 500ml até 25 reais" →

{
  "product": { "category": "acai", "volumeMl": 500, "quantity": 1 },
  "budget": { "maxCents": 2500, "currency": "BRL" },
  "preferences": { "priceWeight": 0.8, "etaWeight": 0.2 },
  "execution": { "requireConfirmation": true },
  "parsing": { "method": "deterministic", "missing": [], "notes": ["default weights…"] }
}

It never invents values: a target budget is only set when the user states one ("idealmente 20"); missing volume/budget are listed in parsing.missing. An IntentFallbackParser interface exists for a future LLM fallback; it is not used.

#Decision (packages/agent/src/decision.ts)

1. Hard constraints (reject with a reason): provenance policy; cart-level total required; category/volume/quantity comparability (a cart with an extra item is not comparable); normalization confidence; region; staleness (> 24 h); budget.
2. Soft factors → confidence: freshness decay after 60 min, provenance (synthetic ×0.5), cart reconciliation.
3. Score = priceWeight × priceScore + etaWeight × etaScore, both min-max normalized among accepted candidates. The formula is printed per candidate.

If the intent has no volume, the volume of the user's current cart is used (and stated); otherwise the output warns that sizes are mixed.

Output: selected option, total, alternatives, rejected (with reasons), savings vs median / current checkout, market median, reasoning lines, confidence, freshness, containsSynthetic, and executability:

• current-checkout — the only executable option;
• own-observation — seen earlier in this browser; must be re-verified;
• market-reference — another account or a fixture; not executable.

#State machine (packages/agent/src/state-machine.ts)

IDLE → INTENT_CAPTURED → MARKET_SEARCH → CANDIDATES_NORMALIZED
     → CONSTRAINTS_APPLIED → BEST_OPTION_SELECTED → USER_CONFIRMATION
     → CHECKOUT_PREPARED → PAYMENT_TARGET_DETECTED → PAYMENT_AUTHORIZED → SETTLED
(any) → ERROR · (no candidates / no valid option) → NO_VALID_OPTION · RESET → IDLE

Guards: CHECKOUT_PREPARED requires USER_CONFIRMED; PAYMENT_AUTHORIZED requires an authorization with confirmedByUser: true whose amount equals the detected payment target and an unexpired target. Amount mismatches between decision, checkout and payment target are recorded as warnings. planPurchase runs automatically only up to USER_CONFIRMATION.