adcontextprotocol/adcp-client/build-generative-seller-agent

Build a Generative Seller Agent

A generative seller does everything a standard seller does (products, media buys, delivery) plus generates creatives from briefs. The buyer sends a creative brief instead of uploading pre-built assets. Your platform resolves the brand identity, generates the creative, and serves it.

A generative seller that sells programmatic inventory MUST also accept standard IAB formats (display images, VAST tags, HTML banners). The generative capability is additive — buyers who already have creatives need to upload them directly.

Pick your fork target

There's no dedicated hello_generative_seller_adapter_*.ts yet — generative-seller is sales-non-guaranteed + creative-generative, so adopters fork the seller adapter and add the build_creative surface.

Declare all your claims (['sales-non-guaranteed', 'creative-generative'], plus 'sales-catalog-driven' if you ingest catalogs for dynamic creative) on createAdcpServerFromPlatform's capabilities.specialisms. Missing the claim fails the grader with "No applicable tracks found" even if every tool works.

For exact response shapes, error codes, and optional fields, docs/llms.txt is the canonical reference.

When to use this skill

• User wants to build a generative DSP or AI ad network
• User's platform both sells inventory and creates/generates creatives
• User mentions "creative from brief", "AI-generated ads", or "generative"

Not this skill:

• Standard seller, no creative generation → skills/build-seller-agent/
• Standalone creative agent (renders but doesn't sell) → skills/build-creative-agent/
• Signals/audience data → skills/build-signals-agent/

Often claimed alongside: creative-template — hybrid creative platforms (Celtra, Bannerflow) claim both; template-driven and AI-driven generation share the same creative library. See Common multi-specialism bundles.

Cross-cutting rules

Every generative seller hits the cross-cutting rules in `../cross-cutting.md`. Plus the seller cross-cutting from `../build-seller-agent/SKILL.md` — generative-seller is additive on top of the seller baseline. The high-traffic ones for generative-seller (deep-linked to the rule):

• `idempotency_key` on build_creative and sync_creatives (in addition to the seller-side mutating tools)
• Webhooks — for async generation completions, use creative_review.${creative_id} as a stable operation_id

Specialism deltas at a glance

`creative-generative` —

• build_creative accepts message + brand.domain + optional quality: draft|production; supports refinement (re-send manifest in)
• Response is { creative_manifest: { format_id, assets } } — not { creative_id, status, quality, preview_url } (those are sync_creatives fields; don't leak them in)
• Each asset in creative_manifest.assets requires an asset_type discriminator — use the typed factories (imageAsset({...}), videoAsset({...}), htmlAsset({...}), urlAsset({...}))
• preview_creative renders use urlRender({...}) / htmlRender({...}) / bothRender({...}) — they inject output_format and enforce the matching preview_url / preview_html at the type level
• Brand resolution: brands register dynamically through sync_accounts (a buyer syncs an account with brand.domain; treat that domain as resolvable). Don't hardcode a brand allowlist. Storyboards use fictional .example TLD brands; a hardcoded list will fail validation.

`sales-non-guaranteed` baseline applies — see `../build-seller-agent/specialisms/sales-non-guaranteed.md`.

`sales-catalog-driven` (optional) — if you ingest catalogs for dynamic creative generation, see `../build-retail-media-agent/SKILL.md`.

Validate locally

# Run the fork-matrix gate against the seller-non-guaranteed baseline
npm run compliance:fork-matrix -- --test-name-pattern="hello-seller-adapter-non-guaranteed"
 
# Or validate your forked agent directly against the generative storyboard
adcp storyboard run http://127.0.0.1:3005/mcp creative_generative \
  --bearer "$ADCP_AUTH_TOKEN" --include-bundles --json

The fork-matrix gate is the three-gate contract from `docs/guides/EXAMPLE-TEST-CONTRACT.md`: tsc strict / storyboard zero-failures / upstream façade.

For deeper validation: `docs/guides/VALIDATE-YOUR-AGENT.md`.

Common shape gotchas

BuildCreativeReturn has 4 valid shapes (framework auto-wraps the bare manifest). Asset discriminators are required — use the typed factories. get_media_buy_delivery requires top-level currency; per-package rows require the billing quintet (package_id, spend, pricing_model, rate, currency). See `../SHAPE-GOTCHAS.md`.

Migration notes

• 6.6 → 6.7: `docs/migration-6.6-to-6.7.md`
• 4.x → 5.x: `docs/migration-4.x-to-5.x.md`