Canary Service: pricing

What this is

Rule-side store for pricing — price rules, promotional campaigns, markdown lifecycles, and historical price audit. Does not execute basket calculation (that's the POS today; Phase 4 of the long arc adds Canary's basket engine).

Tier mix and axis

Property	Value
Port	`:8094`
Axis	B — Resource APIs
Tier mix	Reference (effective-price resolver, single-rule reads) · Change-feed (filtered lists) · Stream (mutations, state transitions) · Bulk window (rule + campaign imports)
Owned tables	`app.price_rules`, `app.promotions`, `app.promotion_rules`, `app.markdowns`, `app.markdown_approvals`, `app.price_history`
Effective-price precedence	markdown > promotion > rule > base price
Markdown lifecycle	`PROPOSED → APPROVED → SCHEDULED → APPLIED → EXPIRED`

Purpose

Pricing rule store with effective-price resolver and explicit promotion stacking semantics. Stacking resolved server-side with applied_rules[] audit trail returned to caller — partners building margin-attribution analytics can trace every applied discount back to its source rule.

Dependencies

canary-identity, canary-item (base prices)
canary-inventory (low-velocity markdown triggers)

Consumers

POS adapters (effective-price calls during basket build)
canary-analytics (publishes effective-price changes for downstream metric attribution)
BI tools (margin attribution)