# thilen-opascope-ai-shopping-assistant-agentic-commerce-protocols-2026-02-10

## Veille

Technical guide to AI shopping assistants 2026, ACP (OpenAI/Stripe) vs UCP (Google/coalition) protocols, merchant implementation, agentic attribution

## Titre Article

AI Shopping Assistant Guide 2026: Agentic Commerce Protocols

## Date

2026-02-10

## URL

https://opascope.com/insights/ai-shopping-assistant-guide-2026-agentic-commerce-protocols/

## Keywords

agentic commerce, AI shopping assistant, ACP, UCP, Universal Commerce Protocol, Agentic Commerce Protocol, OpenAI, Google, Stripe, Shopify, Etsy, agentic checkout, product feed, attribution, schema.org, Amazon Rufus, Alexa+, structured data, Instant Checkout, ChatGPT, Merchant Center, measurement, incrementality testing

## Authors

Max Thilén (Opascope)

## Ton

**Profile**: E-commerce consultant perspective, professional and didactic register, advanced level aimed at decision-makers and technical teams

**Description**: Max Thilén adopts the tone of a strategic analyst writing an exhaustive reference guide. The 29-minute article combines macro vision (McKinsey $3-5T projections, Morgan Stanley) with micro-operational detail (the 5 REST endpoints of the ACP API, the mandatory fields of the product feed). The style is methodical and structured — each protocol is dissected with the same level of detail (status, owner, scope, fees, architecture), enabling direct comparison. The author does not take sides between ACP and UCP but pragmatically concludes that brands need both. The comparison tables, JSON-LD code examples, per-platform roadmaps (Shopify, Etsy, custom), and the attribution section reflect a highly actionable orientation. The target audience consists of e-commerce managers and developers who must prepare their brands for the age of agentic commerce.

## Pense-betes

- **Two competing protocols**: ACP (OpenAI + Stripe, live since Sept. 2025) and UCP (Google + coalition, announced Jan. 2026). ACP is operational — ChatGPT Instant Checkout serves 900 million weekly users. UCP is more ambitious with 20+ partners (Visa, Mastercard, PayPal, Shopify, Walmart, Target, etc.).
- **ACP fees**: 4% commission on every transaction (confirmed Jan. 2026), on top of standard Stripe processing (~2.9% + $0.30). Total ~7% per transaction for the merchant.
- **Modular UCP architecture**: four transports (REST, Anthropic's MCP, Google's A2A, Embedded Protocol), two checkout modes (native within the AI interface vs. iframe to the merchant site), discovery via `/.well-known/ucp` profile. Three capabilities: Checkout, Identity Linking, Order Management.
- **ACP purchase flow**: the user asks for a recommendation → ChatGPT searches merchant feeds → displays results with a "Buy" button → Instant Checkout via Stripe → order placed without ever visiting the merchant site. A complete break from the click-through model.
- **Amazon absent from both protocols**: controls 40% of US e-commerce but refuses to participate. Proprietary strategy with Rufus AI (300M users, +60% conversion), Alexa+ (voice commerce), and Buy for Me (buying from competitors within the Amazon app). Blocked OpenAI's crawlers via robots.txt (600M products removed). The market is thus a triptych: Amazon proprietary / Google UCP / OpenAI ACP.
- **Product data = primary competitive lever**: when paid advertising doesn't reach agents, the quality of structured data becomes the sole differentiator. ACP requires a JSONL/CSV/XML feed with mandatory fields (150-char title, 5000-char use-case-oriented description, ISO 4217 price, availability). UCP relies on Google Merchant Center with 170+ attributes.
- **AI descriptions ≠ SEO**: describe use cases, materials, and benefits, not keywords. Weak example: "Men's Trail Running Shoe – Blue – Size 10". Strong example: "Lightweight trail shoe for technical terrain. Breathable mesh, aggressive lug pattern for wet rock and mud grip."
- **Attribution crisis**: 70-90% of purchase journeys already invisible to analytics; agentic commerce pushes toward 100% invisibility. The first signal is an order webhook. Impossible to measure how often a product is recommended, which competitors are compared, which factors influence the agent. Recommendation: server-side tracking via webhooks, incrementality testing, AI visibility monitoring. Maturity estimated at 18-24 months.
- **Shopify implementation**: ACP → application at chatgpt.com/merchants + channel activation. UCP → automatic via Shopify Agentic Storefronts. Minimal friction.
- **Market projections**: McKinsey $3-5T globally by 2030, Morgan Stanley 10-20% of e-commerce captured by agents ($190-385B), Forrester 20% of B2B sellers facing agent-driven negotiations by end of 2026.
- **Link to existing fiches**: complements the Marette fiche (technical ACP/UCP guide oriented toward French implementation), the NRF 2026 fiche (UCP announcement), and the AP2 fiche (predecessor). Contributes the OpenAI/ACP perspective absent from the other fiches, technical API detail, Amazon's strategy, and the attribution problem.

## RésuméDe400mots

Max Thilén publishes a 29-minute reference guide on the agentic commerce protocols structuring e-commerce in 2026. The starting premise is radical: customers now complete entire purchase journeys inside AI conversations, without ever visiting merchant sites. ChatGPT Instant Checkout serves 900 million weekly users.

Two protocols are competing for this infrastructure. **ACP** (Agentic Commerce Protocol), driven by OpenAI and Stripe, has been operational since September 2025. It imposes a 4% commission per transaction, a structured product feed, and 5 REST endpoints for checkout. The flow is entirely conversational: the user asks, the agent searches, displays a "Buy" button, and Stripe processes payment via a shared token — the agent never sees banking data.

**UCP** (Universal Commerce Protocol), announced by Google in January 2026 at NRF, federates a massive coalition: Shopify, Walmart, Target, Wayfair, Visa, Mastercard, PayPal, and 20 other partners. Its architecture is more modular, with four transport options (REST, MCP, A2A, Embedded) and two checkout modes (native within the AI interface or iframe to the merchant site). Merchants declare their capabilities via a `/.well-known/ucp` profile.

Amazon's absence is strategically significant. Controlling 40% of US e-commerce, Amazon has chosen a proprietary path with Rufus AI (300 million users, +60% conversion), Alexa+ for voice commerce, and "Buy for Me," which lets users buy from competitors within the Amazon app. Amazon has even blocked OpenAI's crawlers, removing 600 million products. The market thus forms a triptych: Amazon proprietary, Google UCP, OpenAI ACP.

The guide details the technical requirements of both protocols, notably the **product data** that becomes the primary competitive lever when paid advertising fails to reach agents. Descriptions must serve natural-language processing, not classic SEO: describing use cases and materials rather than stacking keywords.

The **attribution crisis** is the major challenge: 70-90% of purchase journeys are already invisible to traditional analytics, and agentic commerce approaches 100%. The first measurable signal is an order webhook. Thilén recommends server-side tracking, incrementality testing, and AI visibility monitoring, with maturity estimated at 18-24 months.

Projections are considerable: McKinsey anticipates $3-5 trillion in global revenue by 2030. For brands, the conclusion is pragmatic: both protocols matter. ACP dominates conversational discovery, UCP will capture intentional queries via Google. Different entry points, same customer.

## GrapheDeConnaissance

- OpenAI —a_créé→ Agentic Commerce Protocol (TECHNOLOGIE, 0.97)
- Stripe —a_créé→ Agentic Commerce Protocol (TECHNOLOGIE, 0.97)
- Google —a_créé→ Universal Commerce Protocol (TECHNOLOGIE, 0.98)
- Agentic Commerce Protocol —mesure→ commission de 4% par transaction (MESURE, 0.98)
- Universal Commerce Protocol —utilise→ quatre transports (REST, MCP, A2A, Embedded) (CONCEPT, 0.95)
- Amazon —s_oppose_à→ Agentic Commerce Protocol (TECHNOLOGIE, 0.97)
- Amazon —s_oppose_à→ Universal Commerce Protocol (TECHNOLOGIE, 0.97)
- Amazon —a_créé→ Rufus AI (TECHNOLOGIE, 0.96)
- Rufus AI —améliore→ taux de conversion (+60%) (CONCEPT, 0.9)
- ChatGPT Instant Checkout —mesure→ 900 millions d'utilisateurs hebdomadaires (MESURE, 0.95)
- commerce agentique —réduit→ attribution marketing traditionnelle (CONCEPT, 0.93)
- données produit structurées —remplace→ publicité payante comme levier compétitif (CONCEPT, 0.9)
- Max Thilén —recommande→ implémentation des deux protocoles ACP et UCP (AFFIRMATION, 0.92)
- Shopify —utilise→ Universal Commerce Protocol (TECHNOLOGIE, 0.95)
- McKinsey —prédit→ $3-5T revenus commerce agentique global d'ici 2030 (AFFIRMATION, 0.93)

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