v3.3.0-beta.0

AdCP 3.3.0-beta.0: the protocol-first 3.3 checkpoint. It provides canonical schemas, compliance assets, skills and the protocol manifest for SDK implementation and integration feedback. Use it in development and staging, not production; SDK support follows this cut.

• What's new: https://docs.adcontextprotocol.org/docs/reference/whats-new-in-3-3
• Migration (3.2 → 3.3): https://docs.adcontextprotocol.org/docs/reference/migration/3-2-to-3-3
• Beta program: https://docs.adcontextprotocol.org/docs/reference/3-3-beta
• Changelog: https://github.com/adcontextprotocol/adcp/blob/main/CHANGELOG.md#330-beta0

Verify the tarball before use:

sha256sum -c 3.3.0-beta.0.tgz.sha256
cosign verify-blob --signature 3.3.0-beta.0.tgz.sig --certificate 3.3.0-beta.0.tgz.crt \
  --certificate-identity "https://github.com/adcontextprotocol/adcp/.github/workflows/release.yml@refs/heads/main" \
  --certificate-oidc-issuer https://token.actions.githubusercontent.com 3.3.0-beta.0.tgz