ACP & MCP
How ASP relates to the rest of the agent protocol ecosystem
Complementary, not competing
| protocol | owns | timeline | essence |
|---|---|---|---|
| ACP | editor↔agent live control | present | wire protocol |
| MCP | agent↔tool invocation | present | tool protocol |
| ASP | session persistence, replay, migration | past | storage & migration protocol |
Isomorphism with ACP v2
ACP v2 (draft 2026-07) happens to be isomorphic with ASP on key points:
- "Beyond the turn + multi-client observation" ⇄ ASP's append-only event log + snapshot/cursor
- "Stable IDs + patch semantics (omitted/null/value/chunk-append)" ⇄ ASP's
entityRevision+ delta merge - The
Otherblock ("receivers must preserve raw payload") ⇄ ASP's typedunknownblock
Integration directions: an ACP tap (ASP implementation as an ACP client) for live capture; an ACP agent adapter (ASP implementation as an ACP agent) for replaying stored sessions to an editor.
Divergence: ACP v2 removed the thinking content block; ASP treats thinking (with signature) as resume-critical.
Content-block mapping
| ASP | ACP/MCP |
|---|---|
text | Text |
image | Image / Audio |
reference | ResourceLink / Resource |
unknown | Other — both mandate opaque passthrough |
thinking(+signature) | (none in ACP v2) |
tool-call/tool-result | ToolCall* |
Full detail: asp/spec/acp-mcp.md.