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Track: complete MCP 2026-07-28 protocol upgrade#532

Description

@Dumbris
Dumbris
opened on May 28, 2026

Summary

The MCP 2026-07-28 spec revision (release candidate) is a major, proxy-impacting protocol change. This issue tracks mcpproxy's upgrade. Full scope captured in spec 057-mcp-2026-upgrade (specs/057-mcp-2026-upgrade/spec.md).

⛔ Dependency gate

Implementation is BLOCKED until github.com/mark3labs/mcp-go ships 2026-07-28 support. As of 2026-05-28, pinned v0.54.0 and latest v0.54.1 both target only 2025-11-25. We do not hand-roll protocol primitives ahead of the library.

Breaking changes to address (proxy-specific)

  • Sessions removed / fully stateless; */list MUST NOT vary per connection — reconcile with agent-token scoping + multiuser filtering.
  • initialize/initialized removed → new server/discover RPC + per-request _meta (protocolVersion/clientInfo/clientCapabilities), both as server and client.
  • New REQUIRED headers Mcp-Method, Mcp-Name, MCP-Protocol-Version — proxy must set/validate/forward both directions; -32001 HeaderMismatch.
  • MRTR (input_required + inputResponses) replaces server-initiated sampling/elicitation over SSE.
  • x-mcp-header param→header mirroring.
  • resources/subscribe → subscriptions/listen; GET stream removed.
  • Resource-not-found -32002 → -32602.

Additive opportunities

  • CacheableResult (ttlMs + cacheScope) → amplifies token-savings value prop.
  • Deterministic tool ordering; server:tool prefix now spec-blessed.
  • Header-based routing (avoid JSON body parse); Tasks + MCP Apps extensions.
  • W3C/OTel trace context in _meta → activity log; JSON Schema 2020-12 default.

Deprecations to migrate away from

roots, sampling, logging, HTTP+SSE 2024-11-05 transport (12-month window).

Next steps

  1. Watch mcp-go for a 2026-07-28 release (scheduled tracking agent).
  2. Re-validate spec 057 against the finalized (non-RC) spec when the gate clears.
  3. Run /speckit.plan → /speckit.tasks once unblocked.

Related spec: specs/057-mcp-2026-upgrade/spec.md

Activity

  1. Dumbris commented on Jun 1, 2026

    @Dumbris
    Dumbris
    on Jun 1, 2026 – with Claude
    MemberAuthor

    ⏳ Still blocked — no change (weekly check 2026-06-01)

    Dependency gate: github.com/mark3labs/mcp-go latest release is v0.54.1 (May 25, 2026). LATEST_PROTOCOL_VERSION = "2025-11-25"; ValidProtocolVersions contains only 2025-11-25, 2025-06-18, 2025-03-26, 2024-11-05. The string 2026-07-28 does not appear anywhere in the types file. Library gate is not cleared.

    Spec status: Still a Release Candidate. RC was announced May 21, 2026 (post: The 2026-07-28 MCP Specification Release Candidate). Final specification is scheduled to ship July 28, 2026 — no finalization post yet. No breaking detail changes since last check; confirmed RC details: Mcp-Session-Id header removed, new required headers MCP-Protocol-Version / Mcp-Method / Mcp-Name, initialize/initialized handshake eliminated (client info moves to _meta), error code -32002 → -32602, Tasks API requires migration.

    Tracking: Issue #532 is open. PR #533 is open / not merged (spec doc only, awaiting library gate).

    No action required this week. Will re-check next Sunday.

    Generated by Claude Code

  2. Dumbris commented on Jun 8, 2026

    @Dumbris
    Dumbris
    on Jun 8, 2026 – with Claude
    MemberAuthor

    ⏳ Still blocked — no change (weekly check 2026-06-08)

    Dependency gate: github.com/mark3labs/mcp-go latest is v0.54.1 (released May 25, 2026). LATEST_PROTOCOL_VERSION = "2025-11-25"; ValidProtocolVersions covers 2025-11-25 / 2025-06-18 / 2025-03-26 / 2024-11-05. The string "2026-07-28" does not appear anywhere in mcp/types.go. Gate is not cleared.

    Spec status: MCP 2026-07-28 is still a release candidate — the most recent blog post (May 21, 2026) at blog.modelcontextprotocol.io still uses RC language. The spec is not expected to be finalized until July 28, 2026 itself. No field-name or error-code changes vs. original RC have been detected that would require editing the spec.

    Project status: Issue #532 is open. PR #533 is open, not merged (note: PR title was corrected to "spec 058" in a revision, though tracked here as 057/058).

    No action required yet. Next check: 2026-06-15. Implementation can begin once mcp-go ships a release where "2026-07-28" appears in ValidProtocolVersions.

    Generated by Claude Code

  3. Dumbris commented on Jun 15, 2026

    @Dumbris
    Dumbris
    on Jun 15, 2026 – with Claude
    MemberAuthor

    ⏳ Still blocked — no change (weekly check, 2026-06-15)

    Dependency gate: github.com/mark3labs/mcp-go latest is v0.54.1 (released May 25, 2026). LATEST_PROTOCOL_VERSION is still "2025-11-25"; ValidProtocolVersions contains only 2024/2025 dates. No 2026-07-28 anywhere in the codebase. Library gate is not cleared.

    Spec status: The 2026-07-28 revision is still a release candidate (RC locked May 21, 2026; final ships July 28, 2026 — 43 days out). No breaking-detail changes since the RC was announced. Key breaking items remain as documented in the spec: removal of initialize/initialized handshake, session management eliminated (Mcp-Session-Id gone), new required Mcp-Method / Mcp-Name headers, MCP-Protocol-Version header replacing handshake exchange, missing-resource error code changed from -32002 → -32602.

    Project status: Issue #532 open, no new comments. PR #533 open and intentionally held (June 8 triage note confirmed: "no engineer action needed now; revisit when mcp-go ships 2026-07-28 support").

    Next check: 2026-06-22. Will fire earlier if mcp-go cuts a new release.

    Generated by Claude Code

  4. Dumbris
    added 2 commits that reference this issue on Jun 15, 2026

    docs(spec): add spec 057 — MCP 2026-07-28 protocol upgrade

    9482311

    docs(spec): add spec 057 — MCP 2026-07-28 protocol upgrade

    9574317

  5. Dumbris commented on Jun 22, 2026

    @Dumbris
    Dumbris
    on Jun 22, 2026 – with Claude
    MemberAuthor

    ⏳ Still blocked — no change (weekly check 2026-06-22)

    Dependency gate: mcp-go latest is v0.55.0 (released 2026-06-16). LATEST_PROTOCOL_VERSION is still "2025-11-25"; ValidProtocolVersions is ["2025-11-25", "2025-06-18", "2025-03-26", "2024-11-05"]. The string "2026-07-28" does not appear anywhere in types.go. Library gate not cleared.

    Spec status: The 2026-07-28 revision remains a release candidate (RC announced 2026-05-21). No blog post or changelog entry indicates it has moved to final. No breaking-detail changes detected since last check.

    Project: Issue #532 is open. PR #533 is open, not merged (title now reads "spec 058" — possibly renumbered; still waiting on library).

    Nothing actionable this week. Will recheck next Monday.

    Generated by Claude Code

  6. github-actions
    added a commit that references this issue on Jun 24, 2026

    docs(spec): MCP 2026-07-28 protocol upgrade (spec 058, blocked on mcp…

    b011cda

  7. Dumbris commented on Jun 29, 2026

    @Dumbris
    Dumbris
    on Jun 29, 2026 – with Claude
    MemberAuthor

    ⏳ Still blocked — weekly watcher check, 2026-06-29

    Dependency gate (mcp-go): Latest release is v0.55.1 (2026-06-25). LATEST_PROTOCOL_VERSION in mcp/types.go is still "2025-11-25"; ValidProtocolVersions = ["2025-11-25", "2025-06-18", "2025-03-26", "2024-11-05"]. The string "2026-07-28" does not appear anywhere in the library. Gate remains blocked.

    Spec status: The 2026-07-28 spec remains a Release Candidate (RC locked 2026-05-21). Final is scheduled for the date itself — July 28, 2026 (~4 weeks out). No breaking field/header/error-code changes detected vs. the RC captured in spec 057; no edits to the spec are needed this week.

    Project status: Issue #532 — open. PR #533 (spec/docs) — merged 2026-06-24 (all 46 CI checks passed).

    Next gate: Watch for mcp-go tag ≥ v0.56.0 with LATEST_PROTOCOL_VERSION = "2026-07-28". Expect library support to land in the ~4-week window between now and the final spec ship date.

    Generated by Claude Code

  8. Dumbris commented on Jul 6, 2026

    @Dumbris
    Dumbris
    on Jul 6, 2026 – with Claude
    MemberAuthor

    🟡 Movement — spec finalization imminent, library still blocked (weekly check 2026-07-06)

    mcp-go gate: Latest is v0.55.1 (released 2026-06-25). LATEST_PROTOCOL_VERSION = "2025-11-25" — ValidProtocolVersions still contains only 2025-11-25, 2025-06-18, 2025-03-26, 2024-11-05. The string "2026-07-28" does not appear anywhere in the library. Gate not cleared.

    Spec status: The 2026-07-28 revision is still an RC, but the final specification ships in 22 days (July 28, 2026). The official Tier-1 SDKs (Python v2, TypeScript v2, modelcontextprotocol/go-sdk v1.7.0-pre.1, C# v2 preview) have beta releases with 2026-07-28 support — mark3labs/mcp-go is not among them. No breaking detail changes since baseline: -32602 for missing-resource and Mcp-Method/Mcp-Name headers are confirmed in spec 057 already.

    Project: Issue #532 open. PR #533 merged 2026-06-24.

    Watch signal: With the official Go SDK beta live and the final spec ~3 weeks out, pressure on mark3labs/mcp-go to ship a compatible release should increase sharply. Recommend daily checks of mcp-go releases starting ~July 21.

    Generated by Claude Code

  9. Dumbris commented on Jul 13, 2026

    @Dumbris
    Dumbris
    on Jul 13, 2026 – with Claude
    MemberAuthor

    ⏳ Still blocked — mcp-go v0.56.0 still targets 2025-11-25 (weekly check 2026-07-13)

    mcp-go gate: Latest is v0.56.0 (released ~2026-07-09, up from v0.55.1 last week). LATEST_PROTOCOL_VERSION = "2025-11-25" — ValidProtocolVersions unchanged: 2025-11-25, 2025-06-18, 2025-03-26, 2024-11-05. The string "2026-07-28" does not appear in the library. Gate not cleared.

    Spec status: Still an RC. The 2026-07-28 specification is scheduled to finalize in 15 days (July 28, 2026). No breaking-detail changes detected since last check. The official modelcontextprotocol/go-sdk has a beta with 2026-07-28 support; mark3labs/mcp-go has not yet followed.

    Project: Issue #532 open. PR #533 merged 2026-06-24.

    Watch signal: Spec finalization and library release are now likely within 2 weeks of each other. Daily monitoring of mcp-go releases recommended from ~July 21 onward.

    Generated by Claude Code

  10. Dumbris commented on Jul 20, 2026

    @Dumbris
    Dumbris
    on Jul 20, 2026 – with Claude
    MemberAuthor

    ⏳ Still blocked — no change (weekly check 2026-07-20)

    mcp-go gate: Latest release is v0.56.0 (2026-07-09). LATEST_PROTOCOL_VERSION remains "2025-11-25"; ValidProtocolVersions = ["2025-11-25", "2025-06-18", "2025-03-26", "2024-11-05"]. No 2026-07-28 support present. Implementation of spec 057 cannot begin yet.

    Spec status: 2026-07-28 is still a Release Candidate. The most recent MCP blog post (2026-06-29) covers beta SDKs for the RC — no finalization announcement found. No breaking-detail changes noted since last check.

    Issue #532: Open. PR #533: Merged 2026-06-24 (spec/docs only; implementation blocked pending mcp-go gate).

    Generated by Claude Code

  11. Dumbris commented on Jul 27, 2026

    @Dumbris
    Dumbris
    on Jul 27, 2026 – with Claude
    MemberAuthor

    🟡 Movement — spec final ships tomorrow (2026-07-28), but mark3labs/mcp-go library gate is still not cleared.

    Weekly check — 2026-07-27

    Dependency gate (mark3labs/mcp-go): Latest release is v0.57.0 (released 2025-07-23). LATEST_PROTOCOL_VERSION is still "2025-11-25"; ValidProtocolVersions contains no 2026-07-28 entry. Gate remains blocked. Note: the official MCP Go SDK (github.com/modelcontextprotocol/go-sdk v1.7.0-pre.1) has shipped 2026-07-28 beta support, but mcpproxy depends on mark3labs/mcp-go, which has not been updated.

    Spec status: The 2026-07-28 revision was still RC as of last blog post (2026-06-29, beta SDKs announced). The final spec release date is tomorrow, 2026-07-28 — expect it to land imminently. No new breaking detail changes identified beyond what's already in spec 057 (stateless architecture, no initialize handshake, MCP Apps/Tasks, auth hardening).

    Issue #532: Open. PR #533: Merged 2026-06-24 (spec/docs only — implementation still pending the library gate).

    Next action: Watch mark3labs/mcp-go for a new release tagging 2026-07-28 support, likely following the spec going final tomorrow. Once that drops, spec 057 implementation can begin.

    Generated by Claude Code

  12. Dumbris commented on Aug 3, 2026

    @Dumbris
    Dumbris
    on Aug 3, 2026 – with Claude
    MemberAuthor

    🟡 Movement — 2026-07-28 spec is now FINAL; library gate still blocked (weekly check 2026-08-03)

    Dependency gate (mark3labs/mcp-go): Latest release is v0.57.0 (2026-07-23) — unchanged since last check (July 27). LATEST_PROTOCOL_VERSION = "2025-11-25"; ValidProtocolVersions = ["2025-11-25", "2025-06-18", "2025-03-26", "2024-11-05"]. The string "2026-07-28" does not appear in the library. Gate is still blocked. No new tag has been published since the spec went final 6 days ago.

    Spec status: The 2026-07-28 MCP specification is now officially FINAL — released July 28, 2026 per the MCP blog ("Today, we're officially pushing the release button on the next version of the MCP specification, 2026-07-28"). No breaking-detail changes from RC to final detected; fields, error codes, and headers in spec 057 remain correct. The modelcontextprotocol/go-sdk (official, not mark3labs) has beta support at v1.7.0-pre.1; mark3labs/mcp-go has not yet followed.

    Project: Issue #532 open. PR #533 merged 2026-06-24.

    Watch signal: The spec is final and the window for mark3labs/mcp-go to ship a compatible release is now open. Expect a tagged release within days to weeks. This is the first post-finalization check — escalate to daily monitoring of mcp-go releases.

    Generated by Claude Code

  13. Dumbris commented on Aug 10, 2026

    @Dumbris
    Dumbris
    on Aug 10, 2026 – with Claude
    MemberAuthor

    🟡 Movement — spec is now FINAL, but library gate is still blocked (2026-08-10 weekly check)

    mcp-go gate: mark3labs/mcp-go latest is v0.57.0 (released 2025-07-23). LATEST_PROTOCOL_VERSION = "2025-11-25"; no 2026-07-28 in ValidProtocolVersions. Gate still blocked. Note: the official modelcontextprotocol/go-sdk added 2026-07-28 support (v1.7.0-pre.1), but mcpproxy-go depends on mark3labs, not the official SDK — no impact yet.

    Spec status: 2026-07-28 moved from RC to FINAL on 2026-07-28. Key final-spec breaking changes that may require edits to spec 057: (1) initialize/initialized handshake eliminated; (2) Mcp-Session-Id header removed; (3) Mcp-Method + Mcp-Name headers now mandatory on streamable HTTP; (4) roots/sampling/logging deprecated with 12-month window; (5) legacy HTTP+SSE transport officially deprecated; (6) tasks moved to io.modelcontextprotocol/tasks extension (poll-based tasks/get / tasks/update); (7) list responses gain ttlMs + cacheScope fields. These should be reviewed against spec 057 for any RC→final delta.

    Issue #532: Open. PR #533: Merged (2026-06-24, docs/spec only).

    Generated by Claude Code

  14. Dumbris commented on Aug 17, 2026

    @Dumbris
    Dumbris
    on Aug 17, 2026 – with Claude
    MemberAuthor

    🟢 GATE CLEARED — mcp-go now supports 2026-07-28 (2026-08-17 weekly check)

    mcp-go gate: mark3labs/mcp-go v1.0.0-beta.1 (released 2026-08-12) sets LATEST_PROTOCOL_VERSION = "2026-07-28" and lists it first in ValidProtocolVersions. ⚠️ This is a beta release — stable v0.58.0 (Aug 11) is still on 2025-11-25. Recommend pinning v1.0.0-beta.1 (or waiting for a stable v1.0.0) before starting spec 057 implementation; validate the beta's API surface for breaking changes vs v0.x first.

    Spec 057 can begin once the beta is accepted. Key validation step: re-read spec 057 against the finalized spec before /speckit.plan — the spec moved to FINAL on 2026-07-28, but per last week's check, delta items to review include: tasks moved to io.modelcontextprotocol/tasks extension (poll-based tasks/get/tasks/update), Mcp-Session-Id removed, and list-response ttlMs/cacheScope fields.

    Spec status: 2026-07-28 is FINAL (no longer RC). No new breaking changes found since 2026-08-10 check.

    Issue #532: Open. PR #533: Merged (2026-06-24, spec/docs only).

    Generated by Claude Code

  15. 3 remaining items

  16. github-actions
    added a commit that references this issue on Aug 26, 2026

    chore(deps): exclude mark3labs/mcp-go from the dependabot go group (#…

    4b2c357
  17. Dumbris
    added a commit that references this issue on Aug 27, 2026

    docs(specs): 058 revision — mcp-go v1.0.0-beta.1 clears the 2026-07-2…

    667854f

  18. Dumbris commented on Aug 31, 2026

    @Dumbris
    Dumbris
    on Aug 31, 2026 – with Claude
    MemberAuthor

    🟢 GATE CLEARED — no change since last week (2026-08-31 weekly check)

    • mcp-go latest: v1.0.0-beta.1 (released 2026-08-12) — no new release since last week's check. Still the only version targeting 2026-07-28; stable v0.58.0 (Aug 11) remains on 2025-11-25. No v1.0.0 stable or v1.0.0-beta.2 yet — worth watching for the stable drop before merging implementation work.
    • 2026-07-28 spec: FINAL (unchanged). No new breaking details found this week.
    • Issue Track: complete MCP 2026-07-28 protocol upgrade #532: open. PR docs(spec): MCP 2026-07-28 protocol upgrade (spec 058, blocked on mcp-go) #533: merged (2026-06-24, spec-only).
    • Status: Gate cleared as of 2026-08-12; the 2026-08-23 readiness update (compile probe, 2 failing tests, implementation plan) is the current actionable starting point. Implementation can begin against v1.0.0-beta.1; recommend holding merge until v1.0.0 stable ships or the legacy transport pin is in place.

    Generated by Claude Code

  19. Dumbris
    added 8 commits that reference this issue on Sep 2, 2026

    chore(roadmap): mcp-2026-upgrade to P1, activity-storage-bounds task,…

    fa2a28f

    docs(058): amend the unsatisfiable requirements and generate the task…

    6f493b4

    fix(058): stop relaying an upstream's hop-scoped result metadata

    b15810f

    docs(058): correct three amendment justifications the cross-review re…

    2c1e64d

    fix(058): close two gaps the adversarial review confirmed in the pins…

    9545083

    docs(058): track the two residual gaps the adversarial review confirmed

    56bbe22

    docs(058): implementation plan for the MCP 2026-07-28 upgrade (#1202)

    ca66fbf

    feat(058): adopt mcp-go v1.0.0, pinned inert on both protocol hops (#…

    8a43b64

  20. Dumbris commented on Sep 7, 2026

    @Dumbris
    Dumbris
    on Sep 7, 2026 – with Claude
    MemberAuthor

    🟢 GATE CLEARED — spec 057 implementation can begin

    Weekly watcher check — 2026-09-07

    Dependency gate: CLEARED ✅

    • mcp-go v1.0.0 shipped (released ~2026-09-02) — LATEST_PROTOCOL_VERSION = "2026-07-28", ValidProtocolVersions includes ["2026-07-28", "2025-11-25", ...].
    • The repo's go.mod is already pinned to v1.0.0 (landed via spec 058 branch).

    MCP 2026-07-28 spec: FINAL (no longer RC) ✅

    Published 2026-07-28 as the official release. No field-name or error-code changes vs. the RC that was captured in spec 057 — all breaking details (removed initialize/initialized, new Mcp-Method/Mcp-Name/MCP-Protocol-Version headers, MRTR, subscriptions/listen, -32002→-32602) are confirmed final. Spec 057 does not need structural edits, though a re-validation pass is still recommended before /speckit.plan.

    Issue / PR status

    Next step

    Run /speckit.plan → /speckit.tasks on spec 057-mcp-2026-upgrade to generate the implementation plan. The library gate is gone; only the re-validation pass before coding remains.

    Generated by Claude Code

  21. Dumbris commented on Sep 14, 2026

    @Dumbris
    Dumbris
    on Sep 14, 2026 – with Claude
    MemberAuthor

    🟢 GATE CLEARED — implementation in progress (weekly check 2026-09-14)

    Dependency gate: mcp-go v1.0.0 (stable, released ~2026-09-02) ships 2026-07-28 support — LATEST_PROTOCOL_VERSION = "2026-07-28" / 2026-07-28 present in ValidProtocolVersions. The repo's go.mod is already pinned to v1.0.0 (landed via spec 058 branch). Gate has been cleared since 2026-08-12 (beta.1); stable v1.0.0 confirmed in the 2026-09-07 check.

    Implementation status: Phase 1/2 era-testing harness is real and working (internal/server/protocol_era_test.go). Phase 3+ tasks (list-resolver gating, MCP-* header emission, MRTR, cache-hints, tool-ordering, trace-context, architecture docs, etc.) remain absent per today's gardener run (#1277).

    MCP 2026-07-28 spec: FINAL (no longer RC, published 2026-07-28). No field-name or error-code changes from RC to final that would affect spec 057/058 — existing breaking-change list (removed initialize/initialized, stateless sessions, Mcp-Method/Mcp-Name/MCP-Protocol-Version headers, MRTR, subscriptions/listen, -32002→-32602) remains correct.

    Issue #532: open (tracking). PR #533: merged 2026-06-24 (spec/docs only — done).

    Next: continue Phase 3+ implementation on the 058 branch. No watcher action needed until issue closes.

    Generated by Claude Code

  22. Dumbris
    changed the title [-]Track: upgrade to MCP 2026-07-28 protocol revision (blocked on mcp-go)[/-] [+]Track: complete MCP 2026-07-28 protocol upgrade[/+] on Sep 16, 2026
  23. Dumbris
    added a commit that references this issue on Oct 29, 2026

    feat(mcp): Spec 058 US3 stateless list surfaces (#1691)

    5a8d9d9
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