Why this matters now

In the past two weeks, Google introduced the Universal Commerce Protocol (UCP) to standardize how AI agents discover products and complete purchases, while retailers are beginning to let shoppers buy directly inside assistants (see JD Sports’ example covered by TNW). PayPal is also moving deeper into assistant‑native checkout via ChatGPT (partnership details), and OpenAI has been testing shopping flows inside ChatGPT (Wired). The takeaway: discovery and conversion are collapsing into a single conversation. Payments is where you’ll either convert or stall.

The decision: Which payment rails to enable first

Founders ask us, “Do we start with Google Pay in Gemini’s AI Mode, implement PayPal for Copilot/ChatGPT, or wire Stripe’s agentic stack?” Here’s a pragmatic order of operations:

1. Google Pay via UCP surfaces (Gemini + AI Mode in Search)
   If your products already appear in Google Shopping, turning on agent‑friendly checkout can unlock one‑tap purchases where intent is hottest. Prioritize SKU coverage and pricing parity. UCP is designed to carry real‑time price, availability, and policy data so agents can answer confidently.
2. PayPal for assistant ecosystems (Copilot + ChatGPT)
   PayPal gives you trust, buyer protection, and existing wallet penetration—useful when conversion happens off‑site. If your audience skews marketplace/consumer and you already support PayPal on web, enable it in assistant flows next.
3. Stripe Agentic Commerce Suite (ACS) / ACP endpoints
   Stripe’s approach provides a standardized on‑ramp to publish SKUs and process agent‑initiated checkouts while keeping you merchant‑of‑record. If you run a modern Shopify, WooCommerce, or headless stack, ACS/ACP can reduce bespoke integrations across agents.

Reality check: you don’t have to choose only one. Many brands will run Google Pay on UCP surfaces, PayPal where Copilot/ChatGPT are strongest, and Stripe behind the scenes for orchestration, risk, and settlement. The key is consistent SKU/price/policy data and unified measurement.

10‑Day Rollout Plan (Shopify, WooCommerce, and Headless)

Days 1–2: Readiness and scope

• Confirm you can expose accurate catalog, inventory, taxes, shipping, and returns across feeds and APIs. If you need a crash course, start with our UCP vs. Copilot vs. Stripe ACS decision guide.
• Pick 50–200 SKUs with clean PDPs and stable stock. You’ll expand after telemetry proves lift.
• Define success: agent‑sourced revenue, checkout starts, completion rate, refund rate, and time‑to‑fulfillment.

Days 3–4: Payments configuration

• Google/Gemini (UCP): Ensure Merchant Center is healthy and product feeds include price, inventory, and key policy fields. Theme your brand profile and test agent prompts that mirror your category (“best carry‑on under $200”).
• PayPal (Copilot/ChatGPT): Verify PayPal is enabled in your web checkout and sandbox test assistant‑origin sessions. Maintain pricing parity and transparent fees.
• Stripe ACS/ACP: Stand up create/update/complete session endpoints; map discounts, taxes, shipping tiers, and 3DS rules. Use synthetic users to test edge cases.

Days 5–6: Security, compliance, and consent

• Validate SKU, price, and inventory server‑side on every agent message that changes cart state.
• Enable 3‑D Secure where required and align risk rules for agent user‑agents/IPs.
• Make consent explicit: what data flows from agent → merchant (identity, cart, shipping, payment scope). Run our Agentic Checkout Security Checklist.

Days 7–8: QA and experiments

• Stage a controlled rollout (10–20% of eligible SKUs) on agent surfaces. Test returns, cancellations, and partial refunds from agent‑initiated orders.
• A/B test conversation starters, trust copy, and payment options. Measure impact on clarification rate and checkout starts.

Days 9–10: Measurement and reporting

• Tag agent surfaces with distinct UTM values (e.g., medium=agent; source=gemini|copilot|chatgpt).
• Instrument primitives: chat opens, attribute clarifications, add/remove line items, payment attempts, completes, cancels, refunds.
• Publish a weekly agentic KPI board to leadership. For a template, see our 7‑Day Plan.

Governance: Pricing parity, privacy, and audits

Keep prices and promotions consistent across site, feeds, and agent sessions. Public discourse has already raised concerns about “surveillance pricing” and consent in agentic shopping; ship with transparency from day one. Document what data the agent collects, where it’s stored, and who can access it. Conduct a weekly audit of agent‑sourced orders for price mismatches, tax/shipping errors, or SLA misses.

Playbook by platform

Shopify

• Lock PDP fundamentals (title, variant attributes, materials, returns, warranty). Thin PDPs lead to vague agent answers and lower conversion. If you need to upgrade content fast, use our 48‑hour feed playbook.
• Confirm apps or connectors for PayPal and Stripe are current and 3DS rules match your compliance scope.

WooCommerce

• Audit plugins for Stripe/PayPal compatibility with agent‑initiated sessions and test webhooks for order state changes.
• Cache control: avoid aggressive caching that hides fresh inventory/price from agents.

Headless / Composable

• Expose a reliable pricing/availability API; agents must not rely on scraped PDPs.
• Design idempotent checkout endpoints. Replays happen—be ready.

KPIs that prove lift

• Agent‑sourced revenue and share of total orders.
• Checkout completion rate by payment rail (Google Pay vs. PayPal vs. Card via Stripe).
• Clarification rate (how many Q&A turns before add‑to‑cart) as a proxy for PDP/feed quality.
• Refunds/chargebacks vs. site baseline—signal for consent or policy confusion.
• Fulfillment time from agent order to ship confirmation.

Common pitfalls (and fast fixes)

• Price mismatches between PDP and agent response → Enforce server‑side price validation at create/update/complete.
• Inventory drift mid‑conversation → Re‑check stock at each cart change and again at completion.
• Ambiguous returns/warranty → Pin policy snippets in feeds and ensure verbatim consistency across site, feed, and agent copy.
• No kill switch → Define who can pause agent checkout per surface (Gemini, Copilot, ChatGPT) and how.

What to do this week

1. Light up Google Pay on UCP surfaces for a high‑intent slice of your catalog.
2. Enable PayPal for Copilot/ChatGPT flows where your audience already uses that wallet.
3. Stand up Stripe ACS/ACP endpoints to reduce bespoke integrations and centralize risk/settlement.
4. Ship with pricing parity, clear consent, and audit logs from day one.