fix(docs): replace phantom FORMAT_INCOMPATIBLE with UNSUPPORTED_FEATURE

[bokelley]

Summary

Closes #4852.

create_media_buy docs referenced FORMAT_INCOMPATIBLE in the error table and two JSON response examples, but the code is not defined in static/schemas/source/enums/error-code.json. SDKs that validate errors[].code against the published enum would reject responses built from the docs literally — sellers reading the spec either ship a non-conformant code or invent their own.

Surfaced during review of #4845 (added capability_ids[] to PackageRequest), where the new failure modes were deliberately routed to UNSUPPORTED_FEATURE to avoid inheriting the bug.

Change

Migrated all three references to UNSUPPORTED_FEATURE — the enum value whose semantics ("a requested feature or field is not supported by this seller") match the "format not in the product's accepted set" case exactly. The error-table row was also merged with the sibling UNSUPPORTED_FEATURE row added in #4845 (which covered the v2 capability_ids[] failure modes), so a single row now spans both v1 (format_ids[]) and v2 (capability_ids[]) format-mismatch cases.

Files

• docs/media-buy/task-reference/create_media_buy.mdx — 1 table row merged, 2 JSON example bodies
• .changeset/fix-format-incompatible-phantom-code.md — patch

Test plan

• CI green
• Mintlify renders the merged error-table row cleanly

🤖 Generated with Claude Code

[aao-release-bot]

LGTM. Real bug, clean fix — phantom enum value in publisher docs now points at a code that actually exists on the wire.

Things I checked

• FORMAT_INCOMPATIBLE is absent from static/schemas/source/enums/error-code.json and from every other file in the tree post-merge (grep across docs/, mintlify-docs/, static/schemas/ returns nothing).
• UNSUPPORTED_FEATURE is defined at static/schemas/source/enums/error-code.json:22 with enumDescriptions at L104 — "A requested feature or field is not supported by this seller. Recovery: correctable" — semantic match for the format-mismatch case is exact.
• Three call sites migrated (error-table row + two JSON examples at L933, L1044). The L1060 case is unrelated and was already UNSUPPORTED_FEATURE from #4845.
• Row merge at create_media_buy.mdx:921 is the right shape — single row now spans v1 (format_ids[]) and v2 (capability_ids[]) format-mismatch failure modes, which lines up with the packages[i].capability_ids row at L189 that already specifies UNSUPPORTED_FEATURE as the canonical code.
• Changeset present (.changeset/fix-format-incompatible-phantom-code.md) and correctly typed patch — docs-only fix, no wire shape change.
• Lineage cited (#4845, #4852) and accurate.

Follow-ups (non-blocking)

• Test-plan checkbox "Mintlify renders the merged error-table row cleanly" is unchecked. The merged description cell is dense — worth a glance at the rendered Mintlify preview before assuming the table doesn't wrap awkwardly. Non-blocking; CI gate plus the surrounding rows being similarly verbose means the risk is cosmetic.

Safe to merge.