feat(growth): one-click pack buy links in the credit alert emails (GROWTH_50 #7)

[Deesmo]

What

GROWTH_50 item #7 (council-cleared, Brad GO 2026-07-31): prominent, working one-click buy links in BOTH credit emails — the low-credit alert (sendLowCreditAlert) and the out-of-credits alert (sendCreditsDepletedAlert).

How

• Every pack card is now itself a one-click link to the PR feat(funnel): purchase-intent preservation, pack preselect links, dashboard upsell states #100 GET deep-link https://archtools.dev/pricing?pack=<starter|pro|business> (verified against the pricing.html preselect allowlist at lines 346–348 — exactly those three ids). The page only highlights + scrolls; checkout never auto-fires from a GET (council rule, already pinned by intent-funnel.test.mjs).
• CTA button moved above the fold in the low-credit email ("Buy credits now →"); depleted email keeps its button and gains the clickable pack cards (its old "Option 1" card was inert text).
• Plaintext alternative added to both emails (they previously sent HTML-only) so the buy links work in text-only clients; the send wrappers now pass text through.
• Pack copy rendered from lib/creditPacks.RECOMMENDABLE_PACKS instead of hardcoded credit/price strings (same catalog the 402 funnel uses; sizes pinned by the intent-funnel drift guard). No pricing amounts changed — scripts/check-price-drift.mjs untouched and passing.
• Render logic exported (renderLowCreditAlert / renderCreditsDepletedAlert) following the existing renderVerificationEmail "exported for render tests" pattern. Subjects, styling (layout() + .stat/.btn classes), and the AuditLog once-per-cycle dedup in utils/credits.ts are all unchanged.

Tests

• New api/tests/credit-email-buylinks.test.mjs (28 checks, mirrors reactivation-render.test.mjs): per-pack links present in html and text of both emails; prominent CTA href; no /v1/billing/checkout/subscribe API URL ever appears in an email (auto-fire guard); every linked pack id is in the pricing.html ?pack= allowlist + has a buy button (drift guard); agent id truncation; wrapper text pass-through and alert wiring source pins. Added to the npm test chain.
• intent-funnel.test.mjs email pin updated to the new packHref helper (was a literal-string count that the refactor made stale).

Verification (all run locally in the worktree)

• npx prisma generate && npx tsc --noEmit → clean (exit 0)
• node tests/credit-email-buylinks.test.mjs → 28/28 ✓
• node tests/intent-funnel.test.mjs, tests/credit-alert-dedup.test.mjs, tests/reactivation-render.test.mjs → all pass
• node api/tests/integration.test.js (13/13) + node api/tests/pages.test.js (31/31) — the CI suites
• node scripts/check-price-drift.mjs → OK

No dist/node_modules churn committed (4 source/test files only).

🤖 Generated with Claude Code

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Note

Low Risk
Transactional email content and growth funnel links only; no billing API or credit-deduction logic changes, with tests enforcing no checkout URLs in email bodies.

Overview
Low-credit and credits-depleted emails now drive users to purchase with clickable pack deep-links (/pricing?pack=<id>) built from RECOMMENDABLE_PACKS, instead of static pack copy and a single generic pricing link.

Each recommendable pack is a one-click link in HTML (pack cards are <a> tags) and in a new plaintext body for both alerts; send wrappers pass text through to sendEmail. Render logic is split into exported renderLowCreditAlert / renderCreditsDepletedAlert (same pattern as verification email tests). The depleted email still promotes x402; layout, subjects, and utils/credits.ts alert dedup wiring are unchanged.

Tests: new credit-email-buylinks.test.mjs (links, catalog drift, no checkout API URLs in email, wiring pins) added to npm test; intent-funnel.test.mjs pins the packHref helper instead of counting literal starter URLs.

^{Reviewed by Cursor Bugbot for commit c295ffd. Configure here.}

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