retoor
cc1c130b51
- Agent side: --cap-manifest plus --cap-speak stream-json binding with transcript-diff frames, diff/transcript artifacts, session config - Orchestrator: PTY driver (settle heuristics on PtyProc/TuiVtScreen), stream-json, ACP-stdio (permission/elicit/fs/terminal serving) and A2A drivers (dual draft/current spelling, SSE mapping) - Sessions, fleets: worktrees, master plans, mediated routing, budget refusal, audit log, research auto-answerer, --cap CLI - cap.md contract with drift tests; research/cap-protocol archive - Suites 1119 + 16 green
53 lines
2.8 KiB
Markdown
53 lines
2.8 KiB
Markdown
# A2A protocol specification (current)
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## Metadata
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| Field | Value |
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| Institute | Molodetz Institute — Research & Retrieval Division |
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| Subject | cap-protocol |
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| Document type | Source Dossier |
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| Tier | 1 |
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| Source title | Agent2Agent (A2A) Protocol Specification |
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| Source URL | https://github.com/a2aproject/A2A/blob/main/docs/specification.md |
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| Source type | specification |
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| Source date (published) | Unknown, not stated (living LF doc) |
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| Date researched | 2026-10-18 |
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| Researched by | tai (agent), model: Muse Spark, on behalf of retoor |
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| Research method | direct raw-file fetch, read selectively: full outline, §3.1 ops, §5.3 method mapping, §5.4 errors, discovery sections via grep |
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| Confidence | High |
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| Status | Active |
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## Summary
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Current A2A: JSON-RPC PascalCase methods (`SendMessage`, `SendStreamingMessage`, `CancelTask`...) or colon-REST equivalents (`POST /message:send`), AgentCard at `/.well-known/agent-card.json`, cursor-paginated task listing, extension declarations with required flags. Critically, its method names do NOT match what CAP v1 cites (`message/send`, `tasks/cancel`).
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## Key findings
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- Method mapping (§5.3): JSON-RPC `SendMessage` / REST `POST /message:send`; streaming `SendStreamingMessage` / `POST /message:stream`; cancel `CancelTask` / `POST /tasks/{id}:cancel`. CAP's slash-forms match the pre-1.0 A2A draft, not current A2A.
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- Stream patterns: message-only (exactly one Message then close) or task-lifecycle (Task first, then status/artifact updates, close at terminal state).
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- Terminal states: completed/failed/canceled/rejected; interrupted: input-required (6), auth-required (8).
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- AgentCard discovery via well-known URI; extensions carry uri/description/required/params, matching CAP's `cap-protocol/v1` extension check.
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- A2A error codes (-32001..-32009) collide numerically with CAP's registry but with different meanings; bindings must not mix the two registries.
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## Pros / strengths
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- Normative LF spec with explicit binding-equivalence rules, giving tai a stable target for the A2A driver and expose-server.
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- The extension mechanism is exactly what CAP's compatibility check needs.
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## Cons / limitations / caveats
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- Markdown tables are template-generated (`proto_to_table`), so the .md alone omits field shapes; the .proto file is the real schema.
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- Large surface (push notifications, OAuth flows, mTLS) far beyond what CAP's binding needs; tai implements the message/stream/cancel/card subset only.
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- Read selectively (operations, mappings, discovery); auth and push sections not read.
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## Relevance to tai
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Forces the dual-spelling decision in the naming-drift conclusion: tai's A2A driver must speak CAP-literal draft endpoints to CAP peers and current endpoints to real A2A agents.
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## Changelog
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| Date | Change |
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| 2026-10-18 | Initial dossier created. |
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