retoor
251c3dc2ba
- wire spec: lifecycle, stdio + Streamable HTTP transports, tools, utilities, legacy SSE, versioning, changelog (14 Tier 1) - client ecosystem: Claude Code/VS Code/Cursor/Codex configs, mcp-remote, Smithery, registries, Glama (12 Tier 1) - security/ops: authorization draft, trust model, poisoning, rug pulls, production hardening (12 Tier 1) + 68 Tier 2 cards - conclusions: minimal stdlib client on 2025-11-25, normalizer + resolver agent for pasted configs/GitHub URLs, untrusted-until- consent trust model; nothing built yet - audit PASS (14 subjects, 797 sources, 32 conclusions)
54 lines
3.4 KiB
Markdown
54 lines
3.4 KiB
Markdown
# Versioning policy + current revision
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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 | mcp-client-support |
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| Document type | Source Dossier |
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| Tier | 1 |
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| Source title | Versioning (MCP docs, current) |
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| Source URL | https://modelcontextprotocol.io/docs/learn/versioning |
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| Source publisher / author | Model Context Protocol authors (Anthropic-donated open project; site docs) |
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| Source type | standard |
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| Source date (published) | Unknown - not stated (content served from /docs/2026-07-28/learn/versioning.md; references 2026-07-28 as current) |
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| Date researched | 2026-10-18 |
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| Researched by | tai (agent), model: Claude Sonnet 5, on behalf of retoor |
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| Research method | gather-subagent direct page fetch, parent synthesis from evidence pack |
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| Confidence | High |
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| Status | Active |
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## Summary
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This page states the versioning policy: versions are `YYYY-MM-DD` strings bumped only on backwards-incompatible change, with Draft / Current / Final revision states, and "The **current** protocol version is **2026-07-28**." In 2026-07-28 every request declares its protocol version via the `io.modelcontextprotocol/protocolVersion` key in `_meta`, the server accepts or rejects each request independently, and clients may optionally call the mandatory `server/discover` RPC for up-front version selection. It points at a Backward Compatibility section for the handshake-based revisions (2025-11-25 and earlier).
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## Key findings
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- "The **current** protocol version is **2026-07-28**." Versions are `YYYY-MM-DD` strings, bumped only on backwards-incompatible change.
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- Revisions: Draft / Current / Final.
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- In 2026-07-28: "Every request declares the protocol version… via the `io.modelcontextprotocol/protocolVersion` key in its `_meta` field, and the server accepts or rejects each request independently"; "Clients MAY call `server/discover`, a mandatory RPC," for up-front version selection; "Calling it is optional."
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- "For interoperability with… handshake-based protocol revisions (`2025-11-25` and earlier), see Backward Compatibility."
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## Pros / strengths
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- Date-stamped versions with bump-only-on-breakage give clients a simple compatibility rule: same version string means same wire contract.
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- The per-request versioning model in 2026-07-28 (version in `_meta`, independent accept/reject) is stateless and probe-friendly compared to the handshake.
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- Explicitly preserves the handshake-based line (2025-11-25 and earlier) as an interop target with a dedicated Backward Compatibility section, rather than orphaning it.
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## Cons / limitations / caveats
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- No publish date is stated on the page (only the 2026-07-28 current-version reference and the serving path), per the pack's Uncertainty notes; no explicit author names either.
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- Two wire worlds now coexist (handshake-based 2025-11-25 and earlier vs stateless 2026-07-28), so a compatibility-maximizing client must eventually speak both.
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- The Backward Compatibility section itself was not among the opened sources, so its exact guidance is not captured in this dossier.
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## Relevance to tai
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Flags that the newest spec is stateless/per-request, but handshake-based 2025-11-25 remains the interop baseline a minimal client should target first. Sets the upgrade path: ship 2025-11-25 (handshake, sessions, ping), then add 2026-07-28 (per-request `_meta` version, `server/discover`) later.
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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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