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A channel group is one coherent inventory selection inside a campaign. It combines AdCP inventory dimensions without inventing new channel values. Mobile web display, for example, is:
It is not channel: "mobile_web": mobile_web isn’t an AdCP media channel.
Semicola uses the channel group id to split and label media buys. It doesn’t filter discovery by a group, check selected products against the group’s definition, or turn the definition into package targeting. Check the discovery results and the seller’s product details before you assign a channelGroupId.
Within one dimension, values are alternatives (OR). Across dimensions, they combine (AND). A group with channels: ["ctv", "olv"] and deviceTypes: ["ctv", "mobile"] allows either channel and either device. For pairwise logic such as “CTV on TV devices, or online video on mobile”, make two groups.

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Groups split media buys

One AdCP media buy can’t carry arbitrary combinations of channel, property type, device and format, so Semicola compiles a campaign by this rule:
If a campaign has mobile-web-display and ctv groups, products in each become separate draft buys even with the same seller. They stay in one campaign.

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Save preset groups

Pass channelGroups to save_campaign. A preset is shorthand: Semicola expands it and saves the full definition with its preset version, so a later preset change never alters an existing campaign.
The simple presets make no property, device or format assumption: ctv means the AdCP CTV channel, not only a TV set or only a CTV app. A preset group’s name defaults to the preset’s name (“Mobile web display”, “CTV”…); pass name to change it.

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Define your own group

channels is required and takes AdCP channel values only; put an alias such as “mobile web” in the group’s name, not in channels. A channelGroupId is 1–64 letters, digits, dots, dashes or underscores, unique within the campaign. Over REST (POST or PUT /api/v2/buyer/campaigns), send the saved shape; there’s no preset shorthand:
A custom group’s source is { "kind": "custom" }. The media-buy batch’s campaign.create takes the same saved shape.

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Assign products to a group

When a campaign defines groups, every staging call names one:
  • save_media_buy (products or a proposal): channelGroupId applies to everything staged in that call.
  • POST /api/v2/buyer/media-buys/batch: channelGroupId on each selection.
A missing or unknown channelGroupId is refused with the campaign’s group ids, and a campaign without groups refuses one. Each draft buy records the channelGroupId and channelGroupName that created it. Auto-select assigns each product to the first group whose channels it carries. Groups are immutable once used:
  • A group a staged buy references can’t be removed or redefined (409 CONFLICT: “Add a new group instead.”). Add a new group.
  • Define groups before the campaign’s first buy is staged: adding groups to a campaign that already has an ungrouped buy is refused (409 CONFLICT).

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Report by group

Use get_delivery with the channel_group dimension:
Add filters.channelGroupId to read one group. Buys staged without a group roll up under a null channel group; they’re never guessed from names or products. Channel groups answer “which inventory selection did the buyer ask for?” Campaign targeting answers “who, where or when should it reach?” Keep them separate even when both mention a dimension such as device.