feat(promo): scope-aware promo engine + membership/genesis Lightning discounts

[spe1020]

What

Adds promo-code discounts to the membership Lightning checkouts (Cook+, Pro Kitchen, Founders Club/Genesis) by generalizing the existing cookbook promo engine into a scope-aware engine. Cookbook export behavior is byte-for-byte unchanged.

Decisions (as implemented)

• D1 — apply unit: promo applies to the base USD price computed in integer cents (exact rounding), then cents→USD. Membership + genesis are percent-only (flatOff rejected on those scopes; stays sats for cookbook).
• D2 — stacking: promo computes an effective list USD → the existing 5% Bitcoin discount stacks on the result → then sat conversion. Float kept until the final Math.round at sat conversion.
• D3 — 100%/free: reject percentOff >= 100 and flatOff > 0 on membership + genesis (invalid_for_scope), enforced in the engine and at admin write-time. No free-grant path — every activation stays behind a verified Strike COMPLETED receive.
• D4 — genesis scope: genesis gets its own 'genesis' scope. 'all' covers cookbook + membership but excludes genesis (a founder discount needs an explicit 'genesis' code). Seeded LAUNCH/FREEPACK migrated to explicit scope: 'cookbook'.

Genesis activation was left inline/untouched per the brief — only promo validation + effective-USD calc added ahead of the existing conversion.

Files changed

Engine (Phase 1)

• src/lib/cookbookPricing.ts — PromoScope type + pure scopeAllows()
• src/lib/cookbookPromoStore.server.ts — optional scope on PromoEntry (absent ⇒ 'all', backward-compatible)
• src/lib/cookbookPromo.server.ts — scope-aware applyPromo(kv, code, baseAmount, scope); generic PROMOS_DISABLED kill-switch (legacy COOKBOOK_PROMOS_DISABLED still honored for cookbook); new wrong_scope / invalid_for_scope errors
• src/lib/promoEngine.server.ts — new scope-neutral barrel re-export

Money path (Phase 2)

• src/routes/api/membership/create-lightning-invoice/+server.ts — accepts promoCode, validates server-side, echoes promo block
• src/routes/api/genesis/create-lightning-invoice/+server.ts — same, 'genesis' scope
• src/routes/api/membership/apply-promo/+server.ts — new preview endpoint

Cookbook callers — apply-promo + create-invoice pass 'cookbook' (no behavior change)

Admin (Phase 3) — api/admin/promos upsert validates scope (NIP-98 + body-hash + CODE_RE unchanged); admin page gets a scope selector + scope badge

Checkout UIs (Phase 4) — Cook+, Pro Kitchen, Genesis get a "Have a promo code?" input + Apply (preview), with the displayed price coming from the server response. Stripe path untouched.

Tests/infra — src/lib/promoEngine.test.ts (19 tests), src/test/envMock.ts + $env/dynamic/private alias in vitest.config.ts

Migration note

Legacy KV codes with no scope now default to 'all', so they also start discounting membership checkouts. Re-scope any cookbook-only legacy code to 'cookbook' via /admin/promos.

Verification

• pnpm test — 151/151 pass (132 existing + 19 new: scope matching incl. 'all'/genesis carve-out, USD-cents math, D2 stacking order, D3 rejection, cookbook backward-compat + kill-switches)
• pnpm check — 0 errors, 128 pre-existing warnings (none from this change)

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[Copilot]

Pull request overview

Generalizes the cookbook promo engine into a scope-aware engine and wires it into the membership (Cook+, Pro Kitchen) and genesis (Founders Club) Lightning checkouts. Cookbook behavior is preserved by passing an explicit 'cookbook' scope at existing call sites. Membership/genesis codes are percent-only and capped below 100% so every activation still requires a verified Strike COMPLETED receive, and 'all' deliberately excludes the genesis scope to prevent generic codes from discounting founder slots.

Changes:

• Add PromoScope + scopeAllows() and make applyPromo(kv, code, baseAmount, scope) unit-agnostic (sats for cookbook, USD cents for membership/genesis), with new wrong_scope / invalid_for_scope errors and a generic PROMOS_DISABLED kill-switch alongside the legacy cookbook one.
• New /api/membership/apply-promo preview endpoint plus promo support in /api/membership/create-lightning-invoice and /api/genesis/create-lightning-invoice (promo applied to list USD in integer cents, then 5% BTC discount stacks).
• Admin API + page gain a scope field with write-time enforcement of the membership/genesis percent-only sub-100% rule; checkout pages get a "Have a promo code?" input; new promoEngine.test.ts (19 tests) and a vitest $env/dynamic/private alias.

Reviewed changes

Copilot reviewed 19 out of 19 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/lib/cookbookPricing.ts	Adds PromoScope, ALL_SCOPE_COVERS, and pure scopeAllows().
src/lib/cookbookPromoStore.server.ts	Optional scope on PromoEntry (absent ⇒ 'all').
src/lib/cookbookPromo.server.ts	Scope-aware applyPromo, scope/cap enforcement, dual kill-switches, seeded codes set to 'cookbook'.
src/lib/promoEngine.server.ts	New neutral barrel re-export.
src/routes/api/membership/create-lightning-invoice/+server.ts	Accepts promoCode, validates server-side, stacks BTC discount on promo-adjusted USD, echoes promo.
src/routes/api/genesis/create-lightning-invoice/+server.ts	Same flow under 'genesis' scope; KV/prod guard moved earlier.
src/routes/api/membership/apply-promo/+server.ts	New preview endpoint for membership + founders.
src/routes/api/cookbook-export/{apply-promo,create-invoice}/+server.ts	Pass explicit 'cookbook' scope.
src/routes/api/admin/promos/+server.ts	Validates/normalizes scope and enforces membership/genesis percent-only sub-100%.
src/routes/admin/promos/+page.svelte	Scope selector, scope badge, mirror of write-time guard, page renamed.
src/routes/membership/{cook-plus,pro-kitchen,genesis}-checkout/+page.svelte	Promo input + Apply (Lightning only); reflect server-returned discountedUsdAmount/amountSats.
src/lib/promoEngine.test.ts	Cookbook back-compat, kill-switches, scope matching, USD-cents math, D1/D3 caps, D2 stacking, pure scopeAllows.
vitest.config.ts + src/test/envMock.ts	Alias $env/dynamic/private to a mutable test stub.
src/routes/souschef/+page.svelte	Unrelated: removes the "⌘V works…" helper text and switches bar to justify-end.
package.json	Version bump 4.2.446 → 4.2.449.

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