Story (Required)

Background and Approach (Required)

See Challenging Argo CD Agent Cases v2 document (https://docs.google.com/document/d/1NwQaYxmRva8irx_clPTqRu_YQ8MNeFNXSTJoOgv7ZRs/edit?tab=t.0) for details on new messages and behaviour changes.

This new version of the document:

• Uses checksums to reduce bandwidth, which should significantly reduce bandwidth usage during agent/principal startup
• The previous version (v1) did not have a mechanism for the agent to periodically resync individual entities (e.g. applications). We now have ‘request-update’ for this. In v1, we instead had the ‘hello’ message, which refreshed all applications all at once (which would not scale as well in large environments).
• Better names for messages, to make it more explicit that they are used to synchronized entities

I was hoping to be able to split this into multiple stories, but since all 4 messages interact with each other, they need to be implemented as a single atomic unit.

Acceptance Criteria (Mandatory)

• New messages and message behaviour implemented in argocd-agent, as described in document.
• Unit tests
• Existing E2E tests still passing
  • We should implement new E2E tests as part of this, BUT this story is already large enough as it is. So I will instead open a separate story for those.