Spec hygiene: replace .adcp placeholder domains with RFC 2606 .example

[bokelley]

Filed off Brian's catch on PR #3307: meta.adcp, nytimes.adcp, etc. don't actually exist as domains. They were placeholders dressed up as real URIs across the spec.

Already fixed on #3307

17 files touched by #3307 had their .adcp placeholders replaced with RFC 2606 .example domains (the standard placeholder convention). Examples: meta.adcp/extensions/meta_pixel → meta.example/extensions/meta_pixel.

Still using .adcp (out of #3307 scope, file as separate cleanup)

These files predate the canonical-formats work and still use fictional .adcp domains in their examples / schema descriptions:

• static/test-vectors/transport-error-mapping.json
• static/compliance/source/universal/error-compliance.yaml
• static/compliance/source/universal/error-compliance-signals.yaml
• static/compliance/source/protocols/media-buy/scenarios/create_media_buy_async.yaml
• static/schemas/source/media-buy/list-creative-formats-response.json
• static/schemas/source/creative/list-creative-formats-response.json
• docs/protocol/get_adcp_capabilities.mdx

Fix

Bulk replace \.adcp → \.example in these files. Conservative replacement (test vectors and compliance specs reference placeholder URIs that aren't load-bearing for real wire behavior).

Why this matters

Adopters reading the spec see meta.adcp and reasonably ask "is that a real domain?" Several reviewers on #3307 have asked. RFC 2606 .example domains are unambiguous placeholders; .adcp reads like a real TLD or seller convention.

Small ~30-minute cleanup. Could land as a docs/spec hygiene PR or rolled into another minor.

[bokelley]

Triage

Classification: Doc/typo (schema description string hygiene)
Bucket(s): spec / protocol, web / site / docs
Status: drafting-pr

What the experts said:

• docs-expert: approved — clean fix; .example.com is the right RFC 2606 form; no information lost in the shortened string; result.adcp.major_versions in the MDX is property access, not a domain — leave it alone
• ad-tech-protocol-expert: approved — description-field only, non-normative, --empty changeset is correct; adcp.org is not the org's domain; dist/ copies are immutable snapshots handled by release pipeline
• code-reviewer (pre-PR): approved — non-breaking; changeset format correct; dist/ lag is expected and noted in PR body

My take: Scope is narrower than the issue describes — only 2 of the 7 listed files have actual domain-style .adcp patterns on main; the other 5 contain field names (adcp_error, adcp_task_id) and property access (result.adcp.major_versions), not placeholder URIs. Drafting a PR for the 2 schema files.

Drafting #4655: replaces reference.adcp.org with reference.example.com in creative_agents[].agent_url descriptions in both list-creative-formats-response.json schemas (creative + media-buy). --empty changeset, targets main.

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Triaged by Claude Code. Session: https://claude.ai/code/session_01N6Z46r5L7JxToG8u8w8VKk

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Generated by Claude Code

[bokelley]

Done in PR #3307 commit 50da682 — bulk-replaced .adcp placeholder domains with RFC 2606 .example across 17 PR-touched files. Subsequent commit e2fae6b extended the convention to point v1_format_ref.agent_url at the AAO community-registry mirror (mirror.adcontextprotocol.org/translated/<platform>) for unadopted platforms — replaces the lingering meta.example references on platform-specific format fixtures with the real-namespace community mirror.