> ## Documentation Index
> Fetch the complete documentation index at: https://docs.adcontextprotocol.org/llms.txt
> Use this file to discover all available pages before exploring further.

# Creative representation sets

> Keep equivalent trafficking representations in one immutable creative revision, resolve one against a destination, and retain revision lineage.

A logical creative can arrive before its destination is known. It may carry several equivalent trafficking representations—for example, inline display markup plus an Internal Redirect pair, or VAST 2.0, 3.0, and 4.0 URLs. Preserve those alternatives in one `CreativeRepresentationSet` revision, then resolve exactly one into an ordinary seller-bound creative manifest.

This is not creative rotation or A/B testing. Every entry represents the same creative content through a different delivery contract. A representation set is scoped to one canonical format kind: every representation must share the same `format_kind`. Interchangeable packagings for different media types belong in separate sets or separate `sync_creatives` items—seller selection is choosing between delivery contracts for one format, not between media types.

| Identity            | Meaning                                                                              |
| ------------------- | ------------------------------------------------------------------------------------ |
| `creative_id`       | Durable logical creative                                                             |
| `revision_id`       | Complete immutable buyer-authored content state                                      |
| `representation_id` | One equivalent trafficking form inside that revision                                 |
| `build_variant_id`  | One generated or transformed candidate, which may contain different creative content |
| `locale_variant_id` | One buyer-authored localized asset set                                               |
| served `variant_id` | One agent-assigned immutable execution observed in delivery reporting                |

Selection chooses a `representation_id`. It never chooses or creates one of the variant identities.

## Representation-set object

The set always means “choose exactly one compatible representation.” Arrays inside a manifest asset slot still mean repeatable cardinality; they do not mean representation alternatives.

```json theme={null}
{
  "$schema": "https://adcontextprotocol.org/schemas/3.2.0-beta.8/core/creative-representation-set.json",
  "creative_id": "cr_launch_mrec",
  "revision_id": "rev_2026_08_22_1",
  "revision_content_digest": "sha256:dfab7f7290bba72f6826ee10186f7618d6b53b3037290f72b094294bceaf6835",
  "name": "Launch medium rectangle",
  "representations": [
    {
      "representation_id": "source-inline",
      "format_kind": "display_tag",
      "assets": {
        "serving_tag": {
          "asset_type": "display_tag",
          "delivery_type": "inline_markup",
          "markup_type": "iframe_javascript",
          "markup": "<iframe src=\"https://ads.acme-example.com/render\"></iframe>"
        }
      },
      "source": {
        "system": "acme_ad_server",
        "source_representation": "iframe/JavaScript"
      }
    },
    {
      "representation_id": "source-paired",
      "format_kind": "display_tag",
      "assets": {
        "serving_tag": {
          "asset_type": "display_tag",
          "delivery_type": "paired_redirect",
          "ad_request_url": "https://ads.acme-example.com/ad?slot=42",
          "clickthrough_url": "https://click.acme-example.com/redirect"
        }
      },
      "source": {
        "system": "acme_ad_server",
        "source_representation": "Internal Redirect"
      }
    }
  ]
}
```

`creative_id` identifies the durable creative. `revision_id` identifies this complete immutable buyer input state, and each `representation_id` is stable and unique within that revision. Ingestion stores every valid entry without invoking URLs, executing markup, resolving macros, or discarding an unsupported representation.

## Revision identity

The complete representation set is the revision preimage. Producers remove exactly the top-level `$schema`, `creative_id`, `revision_id`, `revision_content_digest`, and `name` properties, serialize everything else with RFC 8785 JCS, and place the lowercase-hex SHA-256 in `revision_content_digest`. `$schema` is transport/schema-location metadata, not creative content. Other unknown fields and representation array order are significant. Producers and resolvers reject duplicate JSON member names, and resolvers recompute the digest before selection.

Changing any representation, its source metadata, the set-level provenance, representation order, or another unknown revision-bearing field requires a new `revision_id` and digest. Renaming the set does not. Selecting, transcoding, macro-binding, or serving one representation does not mint a new revision.

This extends the ordinary [`sync_creatives` revision contract](/dist/docs/3.2.0-beta.8/creative/task-reference/sync_creatives#creative-revisions): the complete set—not the selected manifest—is bound to `(creative_id, revision_id)`. Reusing that identity with a different digest or canonical content fails with `CREATIVE_REVISION_CONTENT_MISMATCH`. The selected manifest carries the verified digest so a downstream seller can retain the complete-set binding even when it receives only the derived output.

## Seller-bound resolution

Resolution follows this order:

1. Discover the destination's product format option and seller-wide execution capabilities.
2. Filter candidates by canonical `format_kind` and the selected `format_option_ref`.
3. Apply the option's asset shape and delivery-mechanism constraints.
4. For VAST, intersect product and seller version sets.
5. Normalize tracker defaults, bind one exact VAST/DAAST execution version, and match every first-class tracker against the destination's [tracker execution contract](/dist/docs/3.2.0-beta.8/creative/tracker-execution-contracts).
6. Evaluate every declared macro against product and seller macro capabilities as a separate check.
7. Select exactly one compatible representation.

The buyer may perform these checks locally from seller discovery and submit the selected ordinary manifest. On the wire, `build_creative` representation resolution is intentionally narrower: only the destination sales agent may advertise `creative.representation_resolution.supported: true` and accept a set. A standalone creative agent does not own the product or seller execution ceilings and cannot claim seller compatibility. Silent guessing is never allowed.

The request carries `representation_destination.product_id` plus the exact effective product `format_option`. The destination seller verifies that declaration against its current product, every named placement/publisher narrowing, and its current seller-wide execution ceilings. When `placement_refs` is omitted, the output must satisfy the common effective contract for every placement where it may deliver. `target_capability_id` selects the seller's creative-operation route; it is not a substitute for the inventory contract.

Resolution requires explicit compatibility inputs. In particular, every `video_vast` source representation has an exact asset `vast_version`, while the selected product option and seller advertise non-empty plural `vast_versions`. An absent set is unproven and cannot be treated as accepting every version on this opt-in resolution path.

When a first-class `vast_tracker` or `daast_tracker` has no sibling exact-version delivery document, `representation_destination` carries `execution_vast_version` or `execution_daast_version`. The value must belong to the destination acceptance set and is echoed in `representation_selection`. It joins the selected representation and output digest in the execution-review identity, so changing it requires re-resolution and ordinary re-review. Package assignment must preserve the same exact version.

Equivalence is a buyer assertion, not something the set digest proves. The digest proves that the complete asserted set was not changed; it does not prove that two representations render the same ad or behave identically. A seller MUST apply its ordinary validation and review policy to the exact selected output before approving or serving it. The seller does not need to fetch, execute, or approve every unselected candidate, and it MUST NOT treat acceptance of one candidate as approval of another. Different sellers may select different candidates, but each selected output is separately submitted through `sync_creatives` and reviewed before it can serve. A later selection likewise requires an explicit buyer sync and ordinary re-review, so an unreviewed hidden candidate can never replace the approved execution.

Pass a representation set to the destination seller's `build_creative` route with the product contract and an advertised strategy:

```json theme={null}
{
  "$schema": "https://adcontextprotocol.org/schemas/3.2.0-beta.8/media-buy/build-creative-request.json",
  "idempotency_key": "resolve-cr-launch-mrec-rev-1",
  "creative_representation_set": {
    "creative_id": "cr_launch_mrec",
    "revision_id": "rev_2026_08_22_1",
    "revision_content_digest": "sha256:13358fdf61931ccab0567451eb1a5968786a50d31cee8c384e332b39c3d444d4",
    "name": "Launch medium rectangle",
    "representations": [
      {
        "representation_id": "source-paired",
        "format_kind": "display_tag",
        "assets": {
          "serving_tag": {
            "asset_type": "display_tag",
            "delivery_type": "paired_redirect",
            "ad_request_url": "https://ads.acme-example.com/ad?slot=42",
            "clickthrough_url": "https://click.acme-example.com/redirect"
          }
        },
        "source": { "system": "acme_ad_server", "source_representation": "Internal Redirect" }
      }
    ]
  },
  "representation_destination": {
    "product_id": "prod_launch_display",
    "format_option": {
      "format_option_id": "acme_internal_redirect_300x250",
      "format_kind": "display_tag",
      "params": {
        "supported_delivery_types": ["paired_redirect"]
      }
    }
  },
  "representation_selection_strategy": "representation_order",
  "target_capability_id": "display_tag_resolution"
}
```

This is a deterministic, single-output mode. It cannot be combined with generation or transformation instructions, transformers, refinement, evaluators, catalog sampling, creative/variant fan-out, brand-generation context, or media-buy/package tag-generation context. `macro_values` is the one permitted operation that may change the derived manifest: selection happens first, then declared build-time macro binding runs without changing the retained source set. Preview fields may request a sidecar render of that selected output, but preview inputs or context never authorize mutation of the manifest or its digest. A pure resolution response never carries `build_variant_id`.

The output is the normal seller-bound manifest. `representation_selection` carries complete-revision lineage through `sync_creatives` and readback:

```json theme={null}
{
  "$schema": "https://adcontextprotocol.org/schemas/3.2.0-beta.8/core/creative-manifest.json",
  "format_kind": "display_tag",
  "format_option_ref": {
    "scope": "product",
    "format_option_id": "acme_internal_redirect_300x250"
  },
  "representation_selection": {
    "creative_id": "cr_launch_mrec",
    "revision_id": "rev_2026_08_22_1",
    "revision_content_digest": "sha256:13358fdf61931ccab0567451eb1a5968786a50d31cee8c384e332b39c3d444d4",
    "selected_representation_id": "source-paired",
    "strategy": "representation_order",
    "selected_output_digest": "sha256:02735eb8341dc1c2c25b63d20a0a675577407f7500084a67a6ad71ac1bd0e4c3",
    "resolved_by": "seller"
  },
  "assets": {
    "serving_tag": {
      "asset_type": "display_tag",
      "delivery_type": "paired_redirect",
      "ad_request_url": "https://ads.acme-example.com/ad?slot=42",
      "clickthrough_url": "https://click.acme-example.com/redirect"
    }
  }
}
```

The paired redirect stays one asset. A receiver cannot combine its ad-request URL with another row's click-through URL or update either half independently.

`selected_output_digest` is SHA-256 over RFC 8785 JCS of a shared manifest projection. From either the returned `CreativeManifest` or its later `CreativeAsset` sync wrapper, remove exactly top-level `$schema`, `representation_selection`, `creative_id`, `revision_id`, `name`, `tags`, `status`, `weight`, `placement_refs`, `placement_ids`, and `inputs`; include every other field, including unknown delivery fields. The identical projection makes ordinary library wrapping and metadata-only edits digest-neutral while fingerprinting the selected seller-bound output separately from the source revision. A changed selection, macro binding, translation, or transcode may keep the same buyer `revision_id`, but it changes this output fingerprint.

## Sync, review, and readback

On `sync_creatives`, the seller enforces two different invariants:

1. `(creative_id, revision_id, revision_content_digest)` binds immutable buyer source content—the complete representation set, never only the selected entry.
2. `(selected_representation_id, selected_output_digest, execution_vast_version-or-null, execution_daast_version-or-null)` binds the current seller-bound execution submitted for review.

Changing the source set requires a new buyer `revision_id`. Changing only the selected execution does not mint a buyer revision, but it is an `updated` creative and follows the ordinary re-review lifecycle; approval never transfers silently to different execution bytes. `list_creatives` returns the exact current `representation_selection` while that selected execution remains current. A downstream seller that receives only the selected manifest can verify its output digest and retain the asserted source-set digest, but cannot claim it independently inspected hidden source representations.

Resolution is an explicit buyer-initiated operation, not a continuously
reevaluated seller policy. After a selected output is accepted by
`sync_creatives`, later product, placement, VAST, macro, or seller-capability
changes MUST NOT cause the seller to rerun the strategy, replace
`representation_selection`, or move the creative into re-review on behalf of
the buyer. Those changes apply to future resolution requests and assignment
validation. To replace the current execution, the buyer explicitly calls the
destination seller's `build_creative` route with the current destination
contract and then submits the returned manifest through `sync_creatives`.
`build_creative` alone does not mutate the creative library; the subsequent
sync is the buyer-visible update that starts ordinary re-review.

If a seller can no longer serve an already accepted execution, it MUST NOT
silently substitute another representation. It uses the ordinary
seller/system-initiated creative lifecycle and media-buy impairment surfaces,
while preserving the exact selection lineage for audit. Buyers reconcile the
status through `creative.status_changed`, `list_creatives`, and
`get_media_buys`, then explicitly resolve and sync a replacement when needed.
An independent seller-initiated re-review may evaluate the same pinned
execution, but it does not authorize representation re-selection.

Representation resolution is a trafficking-time destination choice, not a
viewer- or device-time fallback mechanism. `highest_compatible_vast` means the
highest exact VAST version accepted by the selected product and seller; it does
not mean the highest version supported by a particular player or device. The
selected representation remains pinned for every execution until the buyer
explicitly resolves and syncs a replacement. Device-specific media selection,
VAST wrapper fallback, and player compatibility remain inside the selected
VAST document and its `MediaFile` alternatives. Buyers that need distinct
device contracts must target separate product options or submit separate
creatives; a representation set never authorizes runtime switching between its
members.

This version does not combine `representation_selection` with the sync-only
`localization` mutation. A selected sync item MUST omit `localization`, including
`null`, and the stored creative MUST NOT already have localization that omission
would preserve. To migrate an existing localized creative, first submit a
separate ordinary sync with `localization: null` and no `representation_selection`;
only after that removal is accepted may the selected output be synced. Locale
topology and materialized locale assets need their own explicit
pre-binding projection; treating them as library metadata would allow served
bytes to change without changing either review fingerprint.

<Warning>
  **Migrating an existing localized creative to representation selection is destructive and non-atomic.** First, submit a `sync_creatives` item with `localization: null` to clear all locale assets — existing localized delivery stops while that sync is under review. Only after the null-sync is accepted may the selected output be synced. There is no atomic path: a re-review window exists between the two steps, and a buyer currently serving localized creatives will experience a delivery gap during migration.
</Warning>

## Resolution failure

When no candidate works, return `CREATIVE_REPRESENTATION_UNRESOLVED`. `error.details` MUST conform to [`error-details/creative-representation-unresolved.json`](https://adcontextprotocol.org/schemas/3.2.0-beta.8/error-details/creative-representation-unresolved.json), with exactly one `representation_rejections` entry for every candidate. Unsupported representations remain in the immutable set; failure does not delete or rewrite them.

```json theme={null}
{
  "code": "CREATIVE_REPRESENTATION_UNRESOLVED",
  "message": "No representation is compatible with the selected format option",
  "recovery": "correctable",
  "details": {
    "representation_rejections": [
      {
        "representation_id": "source-vast-2",
        "code": "vast_version_mismatch",
        "message": "VAST 2.0 is outside the product and seller compatibility intersection"
      },
      {
        "representation_id": "source-vast-4",
        "code": "macro_unsupported",
        "message": "A required player-owned macro is not supported on this execution path"
      },
      {
        "representation_id": "source-vast-trackers",
        "code": "tracker_contract_mismatch",
        "message": "The complete destination contract does not honor this normalized tracker selector"
      }
    ]
  }
}
```

`tracker_contract_mismatch` and `macro_unsupported` are deliberately distinct. A seller reports the former with the manifest asset path, normalized selector identity, and destination option reference. Library-only `sync_creatives` can preserve a selected output and validate its structure, but package assignment must revalidate the trackers against the immutable package snapshot before spend.

## VAST representations

One VAST asset declares one exact `vast_version`; a product option and seller declare accepted sets.

```json theme={null}
{
  "$schema": "https://adcontextprotocol.org/schemas/3.2.0-beta.8/core/creative-representation-set.json",
  "creative_id": "cr_launch_video",
  "revision_id": "rev_7",
  "revision_content_digest": "sha256:67d087e0a6e84185fc9b28d5854b1f9d90958ac902a3d569422af3ba69951154",
  "name": "Launch pre-roll",
  "representations": [
    {
      "representation_id": "source-vast-2",
      "format_kind": "video_vast",
      "assets": {
        "vast_tag": {
          "asset_type": "vast",
          "delivery_type": "url",
          "url": "https://video.acme-example.com/vast/2",
          "vast_version": "2.0"
        }
      },
      "source": { "system": "acme_ad_server", "source_representation": "VAST 2.0 pre-fetch" }
    },
    {
      "representation_id": "source-vast-3",
      "format_kind": "video_vast",
      "assets": {
        "vast_tag": {
          "asset_type": "vast",
          "delivery_type": "url",
          "url": "https://video.acme-example.com/vast/3",
          "vast_version": "3.0"
        }
      },
      "source": { "system": "acme_ad_server", "source_representation": "VAST 3.0 pre-fetch" }
    },
    {
      "representation_id": "source-vast-4",
      "format_kind": "video_vast",
      "assets": {
        "vast_tag": {
          "asset_type": "vast",
          "delivery_type": "url",
          "url": "https://video.acme-example.com/vast/4",
          "vast_version": "4.0"
        }
      },
      "source": { "system": "acme_ad_server", "source_representation": "VAST 4.0 pre-fetch" }
    }
  ]
}
```

If the seller-wide ceiling is `['3.0', '4.0', '4.1', '4.2']` but the selected product accepts only `['3.0', '4.0']`, the compatible candidates are VAST 3.0 and 4.0. `highest_compatible_vast` chooses 4.0 only after that intersection is computed; if multiple compatible candidates declare the same highest exact version, the first in representation array order wins. That strategy is valid only for a `video_vast` destination; using it for another format returns `INVALID_REQUEST` and never silently falls back. `representation_order` always chooses the first compatible entry. Resolution must never relabel the VAST 3.0 asset as 4.0.

## Representation namespaces

`CreativeRepresentationSet.representations[].representation_id` identifies an equivalent trafficking representation within one creative revision. It is distinct from:

* `revision_id`, the complete immutable buyer input state;
* `build_variant_id`, a generated or transformed output leaf;
* `locale_variant_id`, a buyer-authored localized asset set;
* assignment weight or rotation groups; and
* served `variant_id`, an agent-assigned immutable execution returned by `get_creative_delivery`.

Do not reuse values across these namespaces as a shortcut. Preserve the explicit `representation_selection` join instead.

## Related

* [Display ads](/dist/docs/3.2.0-beta.8/creative/channels/display)
* [Video ads](/dist/docs/3.2.0-beta.8/creative/channels/video)
* [Universal macros](/dist/docs/3.2.0-beta.8/creative/universal-macros)
* [Creative manifests](/dist/docs/3.2.0-beta.8/creative/creative-manifests)