Align badge embedding with A2A and ERC-8004; add CAIP identifiers reference

[PeterMarirosansCCD]

Purpose

Brings the Verified by Concordium badge's Agent Card embedding into conformance with the two standards it composes with, and documents the ccd CAIP namespace profile ahead of extending its ChainAgnostic registration.

Cross-referenced against the normative texts: EIP-8004 (current draft) at eips.ethereum.org and the A2A v1.0 specification. Key alignments: A2A prohibits extensions adding top-level card fields, so the badge moves into capabilities.extensions under a versioned extension URI; ERC-8004's current draft places registrations in the anchored registration file, so the agent_uri document becomes one combined JSON valid as both an ERC-8004 registration file and an A2A v1.0 Agent Card. All on-chain references use full CAIP identifiers per the ccd profile (CAIP-2 already registered with ChainAgnostic; CAIP-10/CAIP-19 sections written in registry profile format, ready for submission).

Changes

• agent-registry/concordium-badge.rst: "Embed the badge" rewritten — normative A2A extension embedding (URI https://docs.concordium.com/a2a-extensions/concordium-badge/v1, slimmed params: CAIP-19 tokenAddress, CAIP-10 owner/contracts, verify, verification); new ERC-8004 registrations subsection (numeric agentId, dot-form agentRegistry); legacy note (pre-existing top-level concordium blocks stay valid); rationale admonition so the block isn't moved back to top level; standards list updated.
• agent-registry/agent-card.rst: intro, field tables, and example replaced with the combined ERC-8004 + A2A v1.0 document; retires the previous snake_case concordium block format that diverged from the badge page.
• caip-identifiers.rst (new): ccd namespace profile in ChainAgnostic page format — CAIP-2 (registered, matches the live registry profile), CAIP-10 accounts + dot-form contracts, CAIP-19 (cis-2, plt, slip44:919). The CAIP-10/19 sections are copy-ready for the namespaces registry PR so docs and submission cannot drift.
• technical-reference/index.rst: new Standards caption (grid + toctree) holding the CAIP page.
• public/a2a-extensions/concordium-badge/v1/index.html (new): static spec page so the extension URI resolves (public/ is copied to the site root by scripts/build.sh).
• public/llms.txt: new CAIP entry; refreshed descriptions for the badge and Agent Card pages.

Notes for reviewers: The extension URI is permanent for v1 once cards carry it — please treat the URI string and the params schema as frozen; breaking changes mint /v2. Existing registered agents are unaffected (verification is placement-agnostic); new/re-anchored cards adopt the extension form. Service-side changes (MCP build_agent_card, resolver dual-read, agentcards.site template) are deliberately out of scope.

Checklist

• My code follows the style of this project. (doc8 clean across source/)
• The code compiles without warnings. (full mainnet build with -W passes; all cross-references resolve; branch content verified byte-identical to the locally built tree)
• I have performed a self-review of the changes.
• I have documented my code, in particular the intent of the hard-to-understand areas.
• (If necessary) I have updated the CHANGELOG. (not applicable)

[github-actions]

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2026-08-31 19:48 UTC