Implement SEP-2352: Clarify authorization server binding and migration #879

Closed
#998
Closed
Implement SEP-2352: Clarify authorization server binding and migration#879
#998
Labels
2026-07-28P2Medium: important but non-blocking improvementT-enhancementNew features and enhancementsT-securitySecurity-related changesT-transportTransport layer changes
Milestone
2026-07-28 spec

Description

@alexhancock
alexhancock
opened on Jun 2, 2026

SEP-2352: Clarify authorization server binding and migration — rust-sdk implementation

Spec PR:modelcontextprotocol/modelcontextprotocol#2352
Track: Specification · Stage: accepted · Priority: P0 · Theme: Enterprise Readiness
Needs code changes: Yes (Medium)

Summary

Multi-AS guidance:

  • Clients SHOULD maintain separate registration state per authorization server and MUST NOT assume cross-AS credential validity.
  • New "Authorization Server Binding" rules: DCR / pre-registered credentials must be keyed by issuer; CIMD client_ids are portable; clients should error on AS mismatch.

Why this needs code changes in rust-sdk

The OAuth client in crates/rmcp/src/transport/auth.rs persists credentials and registration state
via the CredentialStore trait (StoredCredentials, InMemoryCredentialStore) and the
StateStore trait (StoredAuthorizationState, InMemoryStateStore). Today these are effectively
single-AS: StoredCredentials and the in-memory stores are not keyed by issuer, and
AuthorizationManager holds one metadata: Option<AuthorizationMetadata> (whose issuer field
exists but isn't used to partition stored credentials). So credentials from one AS could be reused
against another, which SEP-2352 forbids.

Proposed work

  • Key CredentialStore / StateStore entries by issuer — either add an issuer discriminator to StoredCredentials / load/save keys, or make the in-memory stores HashMap<issuer, …> so per-AS state is isolated.
  • On token use, compare the active AuthorizationMetadata.issuer against the issuer the stored credentials were minted for; on mismatch return a clear AuthError (add a variant, e.g. AuthError::AuthorizationServerMismatch).
  • Treat CIMD client_ids as portable (don't tie those to a single issuer), but keep DCR/pre-registered credentials issuer-bound.
  • Update register_client / configure_client_id / get_credentials paths to read/write the issuer-keyed store.
  • Add tests: two ASes with distinct registrations don't cross-contaminate; mismatch is rejected.

Affected areas

crates/rmcp/src/transport/auth.rs (CredentialStore/StoredCredentials, StateStore/StoredAuthorizationState, InMemory*Store, AuthorizationManager, AuthError).

Notes / risks

  • Part of the Enterprise Readiness auth cluster (837, 2350, 2351, 2468). Bundle into one auth PR/effort to share test scaffolding.

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    2026-07-28P2Medium: important but non-blocking improvementT-enhancementNew features and enhancementsT-securitySecurity-related changesT-transportTransport layer changes

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    , 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
     blocks\n(function() {\n function addCopyButtons() {\n document.querySelectorAll('pre code').forEach(function(codeBlock) {\n if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;\n codeBlock.parentElement.setAttribute('data-copy-added', 'true');\n \n var btn = document.createElement('button');\n btn.textContent = 'Copy';\n btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';\n btn.onmouseover = function() { this.style.opacity = '1'; };\n btn.onmouseout = function() { this.style.opacity = '0.7'; };\n btn.onclick = function() {\n navigator.clipboard.writeText(codeBlock.textContent).then(function() {\n btn.textContent = 'Copied!';\n setTimeout(function() { btn.textContent = 'Copy'; }, 1500);\n });\n };\n codeBlock.parentElement.style.position = 'relative';\n codeBlock.parentElement.appendChild(btn);\n });\n }\n \n addCopyButtons();\n \n // Re-run on dynamic content\n var observer = new MutationObserver(addCopyButtons);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Add Copy Buttons to Code Blocks");
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

    Skip to content
    Implement SEP-2352: Clarify authorization server binding and migration #879
    Closed
    #998
    Closed
    Implement SEP-2352: Clarify authorization server binding and migration#879
    #998
    Labels
    2026-07-28P2Medium: important but non-blocking improvementT-enhancementNew features and enhancementsT-securitySecurity-related changesT-transportTransport layer changes
    Milestone
    2026-07-28 spec
    Description
    @alexhancock
    alexhancock
    opened on Jun 2, 2026
    SEP-2352: Clarify authorization server binding and migration — rust-sdk implementation
    Spec PR:modelcontextprotocol/modelcontextprotocol#2352
    Track: Specification · Stage: accepted · Priority: P0 · Theme: Enterprise Readiness
    Needs code changes: Yes (Medium)
    Summary
    Multi-AS guidance:
    • Clients SHOULD maintain separate registration state per authorization server and MUST NOT assume cross-AS credential validity.
    • New "Authorization Server Binding" rules: DCR / pre-registered credentials must be keyed by issuer; CIMD client_ids are portable; clients should error on AS mismatch.
    Why this needs code changes in rust-sdk
    The OAuth client in crates/rmcp/src/transport/auth.rs persists credentials and registration state
    
via the CredentialStore trait (StoredCredentials, InMemoryCredentialStore) and the
    StateStore trait (StoredAuthorizationState, InMemoryStateStore). Today these are effectively
    single-AS: StoredCredentials and the in-memory stores are not keyed by issuer, and
    AuthorizationManager holds one metadata: Option<AuthorizationMetadata> (whose issuer field
    
exists but isn't used to partition stored credentials). So credentials from one AS could be reused
    
against another, which SEP-2352 forbids.
    Proposed work
    •  Key CredentialStore / StateStore entries by issuer — either add an issuer discriminator to StoredCredentials / load/save keys, or make the in-memory stores HashMap<issuer, …> so per-AS state is isolated.
    •  On token use, compare the active AuthorizationMetadata.issuer against the issuer the stored credentials were minted for; on mismatch return a clear AuthError (add a variant, e.g. AuthError::AuthorizationServerMismatch).
    •  Treat CIMD client_ids as portable (don't tie those to a single issuer), but keep DCR/pre-registered credentials issuer-bound.
    •  Update register_client / configure_client_id / get_credentials paths to read/write the issuer-keyed store.
    •  Add tests: two ASes with distinct registrations don't cross-contaminate; mismatch is rejected.
    Affected areas
    crates/rmcp/src/transport/auth.rs (CredentialStore/StoredCredentials, StateStore/StoredAuthorizationState, InMemory*Store, AuthorizationManager, AuthError).
    Notes / risks
    • Part of the Enterprise Readiness auth cluster (837, 2350, 2351, 2468). Bundle into one auth PR/effort to share test scaffolding.
    Metadata
    Metadata
    Assignees
    No one assigned
      Labels
      2026-07-28P2Medium: important but non-blocking improvementT-enhancementNew features and enhancementsT-securitySecurity-related changesT-transportTransport layer changes
      Type
      No type
      Projects
      Milestone
      Relationships
      None yet
      Development
      No branches or pull requests
      Issue actions
      
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix");
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

      Skip to content
      Implement SEP-2352: Clarify authorization server binding and migration #879
      Closed
      #998
      Closed
      Implement SEP-2352: Clarify authorization server binding and migration#879
      #998
      Labels
      2026-07-28P2Medium: important but non-blocking improvementT-enhancementNew features and enhancementsT-securitySecurity-related changesT-transportTransport layer changes
      Milestone
      2026-07-28 spec
      Description
      @alexhancock
      alexhancock
      opened on Jun 2, 2026
      SEP-2352: Clarify authorization server binding and migration — rust-sdk implementation
      Spec PR:modelcontextprotocol/modelcontextprotocol#2352
      Track: Specification · Stage: accepted · Priority: P0 · Theme: Enterprise Readiness
      Needs code changes: Yes (Medium)
      Summary
      Multi-AS guidance:
      • Clients SHOULD maintain separate registration state per authorization server and MUST NOT assume cross-AS credential validity.
      • New "Authorization Server Binding" rules: DCR / pre-registered credentials must be keyed by issuer; CIMD client_ids are portable; clients should error on AS mismatch.
      Why this needs code changes in rust-sdk
      The OAuth client in crates/rmcp/src/transport/auth.rs persists credentials and registration state
      
via the CredentialStore trait (StoredCredentials, InMemoryCredentialStore) and the
      StateStore trait (StoredAuthorizationState, InMemoryStateStore). Today these are effectively
      single-AS: StoredCredentials and the in-memory stores are not keyed by issuer, and
      AuthorizationManager holds one metadata: Option<AuthorizationMetadata> (whose issuer field
      
exists but isn't used to partition stored credentials). So credentials from one AS could be reused
      
against another, which SEP-2352 forbids.
      Proposed work
      •  Key CredentialStore / StateStore entries by issuer — either add an issuer discriminator to StoredCredentials / load/save keys, or make the in-memory stores HashMap<issuer, …> so per-AS state is isolated.
      •  On token use, compare the active AuthorizationMetadata.issuer against the issuer the stored credentials were minted for; on mismatch return a clear AuthError (add a variant, e.g. AuthError::AuthorizationServerMismatch).
      •  Treat CIMD client_ids as portable (don't tie those to a single issuer), but keep DCR/pre-registered credentials issuer-bound.
      •  Update register_client / configure_client_id / get_credentials paths to read/write the issuer-keyed store.
      •  Add tests: two ASes with distinct registrations don't cross-contaminate; mismatch is rejected.
      Affected areas
      crates/rmcp/src/transport/auth.rs (CredentialStore/StoredCredentials, StateStore/StoredAuthorizationState, InMemory*Store, AuthorizationManager, AuthError).
      Notes / risks
      • Part of the Enterprise Readiness auth cluster (837, 2350, 2351, 2468). Bundle into one auth PR/effort to share test scaffolding.
      Metadata
      Metadata
      Assignees
      No one assigned
        Labels
        2026-07-28P2Medium: important but non-blocking improvementT-enhancementNew features and enhancementsT-securitySecurity-related changesT-transportTransport layer changes
        Type
        No type
        Projects
        Milestone
        Relationships
        None yet
        Development
        No branches or pull requests
        Issue actions
        
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

        Skip to content
        Implement SEP-2352: Clarify authorization server binding and migration #879
        Closed
        #998
        Closed
        Implement SEP-2352: Clarify authorization server binding and migration#879
        #998
        Labels
        2026-07-28P2Medium: important but non-blocking improvementT-enhancementNew features and enhancementsT-securitySecurity-related changesT-transportTransport layer changes
        Milestone
        2026-07-28 spec
        Description
        @alexhancock
        alexhancock
        opened on Jun 2, 2026
        SEP-2352: Clarify authorization server binding and migration — rust-sdk implementation
        Spec PR:modelcontextprotocol/modelcontextprotocol#2352
        Track: Specification · Stage: accepted · Priority: P0 · Theme: Enterprise Readiness
        Needs code changes: Yes (Medium)
        Summary
        Multi-AS guidance:
        • Clients SHOULD maintain separate registration state per authorization server and MUST NOT assume cross-AS credential validity.
        • New "Authorization Server Binding" rules: DCR / pre-registered credentials must be keyed by issuer; CIMD client_ids are portable; clients should error on AS mismatch.
        Why this needs code changes in rust-sdk
        The OAuth client in crates/rmcp/src/transport/auth.rs persists credentials and registration state
        
via the CredentialStore trait (StoredCredentials, InMemoryCredentialStore) and the
        StateStore trait (StoredAuthorizationState, InMemoryStateStore). Today these are effectively
        single-AS: StoredCredentials and the in-memory stores are not keyed by issuer, and
        AuthorizationManager holds one metadata: Option<AuthorizationMetadata> (whose issuer field
        
exists but isn't used to partition stored credentials). So credentials from one AS could be reused
        
against another, which SEP-2352 forbids.
        Proposed work
        •  Key CredentialStore / StateStore entries by issuer — either add an issuer discriminator to StoredCredentials / load/save keys, or make the in-memory stores HashMap<issuer, …> so per-AS state is isolated.
        •  On token use, compare the active AuthorizationMetadata.issuer against the issuer the stored credentials were minted for; on mismatch return a clear AuthError (add a variant, e.g. AuthError::AuthorizationServerMismatch).
        •  Treat CIMD client_ids as portable (don't tie those to a single issuer), but keep DCR/pre-registered credentials issuer-bound.
        •  Update register_client / configure_client_id / get_credentials paths to read/write the issuer-keyed store.
        •  Add tests: two ASes with distinct registrations don't cross-contaminate; mismatch is rejected.
        Affected areas
        crates/rmcp/src/transport/auth.rs (CredentialStore/StoredCredentials, StateStore/StoredAuthorizationState, InMemory*Store, AuthorizationManager, AuthError).
        Notes / risks
        • Part of the Enterprise Readiness auth cluster (837, 2350, 2351, 2468). Bundle into one auth PR/effort to share test scaffolding.
        Metadata
        Metadata
        Assignees
        No one assigned
          Labels
          2026-07-28P2Medium: important but non-blocking improvementT-enhancementNew features and enhancementsT-securitySecurity-related changesT-transportTransport layer changes
          Type
          No type
          Projects
          Milestone
          Relationships
          None yet
          Development
          No branches or pull requests
          Issue actions
          
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

          Skip to content
          Implement SEP-2352: Clarify authorization server binding and migration #879
          Closed
          #998
          Closed
          Implement SEP-2352: Clarify authorization server binding and migration#879
          #998
          Labels
          2026-07-28P2Medium: important but non-blocking improvementT-enhancementNew features and enhancementsT-securitySecurity-related changesT-transportTransport layer changes
          Milestone
          2026-07-28 spec
          Description
          @alexhancock
          alexhancock
          opened on Jun 2, 2026
          SEP-2352: Clarify authorization server binding and migration — rust-sdk implementation
          Spec PR:modelcontextprotocol/modelcontextprotocol#2352
          Track: Specification · Stage: accepted · Priority: P0 · Theme: Enterprise Readiness
          Needs code changes: Yes (Medium)
          Summary
          Multi-AS guidance:
          • Clients SHOULD maintain separate registration state per authorization server and MUST NOT assume cross-AS credential validity.
          • New "Authorization Server Binding" rules: DCR / pre-registered credentials must be keyed by issuer; CIMD client_ids are portable; clients should error on AS mismatch.
          Why this needs code changes in rust-sdk
          The OAuth client in crates/rmcp/src/transport/auth.rs persists credentials and registration state
          
via the CredentialStore trait (StoredCredentials, InMemoryCredentialStore) and the
          StateStore trait (StoredAuthorizationState, InMemoryStateStore). Today these are effectively
          single-AS: StoredCredentials and the in-memory stores are not keyed by issuer, and
          AuthorizationManager holds one metadata: Option<AuthorizationMetadata> (whose issuer field
          
exists but isn't used to partition stored credentials). So credentials from one AS could be reused
          
against another, which SEP-2352 forbids.
          Proposed work
          •  Key CredentialStore / StateStore entries by issuer — either add an issuer discriminator to StoredCredentials / load/save keys, or make the in-memory stores HashMap<issuer, …> so per-AS state is isolated.
          •  On token use, compare the active AuthorizationMetadata.issuer against the issuer the stored credentials were minted for; on mismatch return a clear AuthError (add a variant, e.g. AuthError::AuthorizationServerMismatch).
          •  Treat CIMD client_ids as portable (don't tie those to a single issuer), but keep DCR/pre-registered credentials issuer-bound.
          •  Update register_client / configure_client_id / get_credentials paths to read/write the issuer-keyed store.
          •  Add tests: two ASes with distinct registrations don't cross-contaminate; mismatch is rejected.
          Affected areas
          crates/rmcp/src/transport/auth.rs (CredentialStore/StoredCredentials, StateStore/StoredAuthorizationState, InMemory*Store, AuthorizationManager, AuthError).
          Notes / risks
          • Part of the Enterprise Readiness auth cluster (837, 2350, 2351, 2468). Bundle into one auth PR/effort to share test scaffolding.
          Metadata
          Metadata
          Assignees
          No one assigned
            Labels
            2026-07-28P2Medium: important but non-blocking improvementT-enhancementNew features and enhancementsT-securitySecurity-related changesT-transportTransport layer changes
            Type
            No type
            Projects
            Milestone
            Relationships
            None yet
            Development
            No branches or pull requests
            Issue actions
            
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

            Skip to content
            Implement SEP-2352: Clarify authorization server binding and migration #879
            Closed
            #998
            Closed
            Implement SEP-2352: Clarify authorization server binding and migration#879
            #998
            Labels
            2026-07-28P2Medium: important but non-blocking improvementT-enhancementNew features and enhancementsT-securitySecurity-related changesT-transportTransport layer changes
            Milestone
            2026-07-28 spec
            Description
            @alexhancock
            alexhancock
            opened on Jun 2, 2026
            SEP-2352: Clarify authorization server binding and migration — rust-sdk implementation
            Spec PR:modelcontextprotocol/modelcontextprotocol#2352
            Track: Specification · Stage: accepted · Priority: P0 · Theme: Enterprise Readiness
            Needs code changes: Yes (Medium)
            Summary
            Multi-AS guidance:
            • Clients SHOULD maintain separate registration state per authorization server and MUST NOT assume cross-AS credential validity.
            • New "Authorization Server Binding" rules: DCR / pre-registered credentials must be keyed by issuer; CIMD client_ids are portable; clients should error on AS mismatch.
            Why this needs code changes in rust-sdk
            The OAuth client in crates/rmcp/src/transport/auth.rs persists credentials and registration state
            
via the CredentialStore trait (StoredCredentials, InMemoryCredentialStore) and the
            StateStore trait (StoredAuthorizationState, InMemoryStateStore). Today these are effectively
            single-AS: StoredCredentials and the in-memory stores are not keyed by issuer, and
            AuthorizationManager holds one metadata: Option<AuthorizationMetadata> (whose issuer field
            
exists but isn't used to partition stored credentials). So credentials from one AS could be reused
            
against another, which SEP-2352 forbids.
            Proposed work
            •  Key CredentialStore / StateStore entries by issuer — either add an issuer discriminator to StoredCredentials / load/save keys, or make the in-memory stores HashMap<issuer, …> so per-AS state is isolated.
            •  On token use, compare the active AuthorizationMetadata.issuer against the issuer the stored credentials were minted for; on mismatch return a clear AuthError (add a variant, e.g. AuthError::AuthorizationServerMismatch).
            •  Treat CIMD client_ids as portable (don't tie those to a single issuer), but keep DCR/pre-registered credentials issuer-bound.
            •  Update register_client / configure_client_id / get_credentials paths to read/write the issuer-keyed store.
            •  Add tests: two ASes with distinct registrations don't cross-contaminate; mismatch is rejected.
            Affected areas
            crates/rmcp/src/transport/auth.rs (CredentialStore/StoredCredentials, StateStore/StoredAuthorizationState, InMemory*Store, AuthorizationManager, AuthError).
            Notes / risks
            • Part of the Enterprise Readiness auth cluster (837, 2350, 2351, 2468). Bundle into one auth PR/effort to share test scaffolding.
            Metadata
            Metadata
            Assignees
            No one assigned
              Labels
              2026-07-28P2Medium: important but non-blocking improvementT-enhancementNew features and enhancementsT-securitySecurity-related changesT-transportTransport layer changes
              Type
              No type
              Projects
              Milestone
              Relationships
              None yet
              Development
              No branches or pull requests
              Issue actions
              
, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

              Skip to content
              Implement SEP-2352: Clarify authorization server binding and migration #879
              Closed
              #998
              Closed
              Implement SEP-2352: Clarify authorization server binding and migration#879
              #998
              Labels
              2026-07-28P2Medium: important but non-blocking improvementT-enhancementNew features and enhancementsT-securitySecurity-related changesT-transportTransport layer changes
              Milestone
              2026-07-28 spec
              Description
              @alexhancock
              alexhancock
              opened on Jun 2, 2026
              SEP-2352: Clarify authorization server binding and migration — rust-sdk implementation
              Spec PR:modelcontextprotocol/modelcontextprotocol#2352
              Track: Specification · Stage: accepted · Priority: P0 · Theme: Enterprise Readiness
              Needs code changes: Yes (Medium)
              Summary
              Multi-AS guidance:
              • Clients SHOULD maintain separate registration state per authorization server and MUST NOT assume cross-AS credential validity.
              • New "Authorization Server Binding" rules: DCR / pre-registered credentials must be keyed by issuer; CIMD client_ids are portable; clients should error on AS mismatch.
              Why this needs code changes in rust-sdk
              The OAuth client in crates/rmcp/src/transport/auth.rs persists credentials and registration state
              
via the CredentialStore trait (StoredCredentials, InMemoryCredentialStore) and the
              StateStore trait (StoredAuthorizationState, InMemoryStateStore). Today these are effectively
              single-AS: StoredCredentials and the in-memory stores are not keyed by issuer, and
              AuthorizationManager holds one metadata: Option<AuthorizationMetadata> (whose issuer field
              
exists but isn't used to partition stored credentials). So credentials from one AS could be reused
              
against another, which SEP-2352 forbids.
              Proposed work
              •  Key CredentialStore / StateStore entries by issuer — either add an issuer discriminator to StoredCredentials / load/save keys, or make the in-memory stores HashMap<issuer, …> so per-AS state is isolated.
              •  On token use, compare the active AuthorizationMetadata.issuer against the issuer the stored credentials were minted for; on mismatch return a clear AuthError (add a variant, e.g. AuthError::AuthorizationServerMismatch).
              •  Treat CIMD client_ids as portable (don't tie those to a single issuer), but keep DCR/pre-registered credentials issuer-bound.
              •  Update register_client / configure_client_id / get_credentials paths to read/write the issuer-keyed store.
              •  Add tests: two ASes with distinct registrations don't cross-contaminate; mismatch is rejected.
              Affected areas
              crates/rmcp/src/transport/auth.rs (CredentialStore/StoredCredentials, StateStore/StoredAuthorizationState, InMemory*Store, AuthorizationManager, AuthError).
              Notes / risks
              • Part of the Enterprise Readiness auth cluster (837, 2350, 2351, 2468). Bundle into one auth PR/effort to share test scaffolding.
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                2026-07-28P2Medium: important but non-blocking improvementT-enhancementNew features and enhancementsT-securitySecurity-related changesT-transportTransport layer changes
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

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                Implement SEP-2352: Clarify authorization server binding and migration #879
                Closed
                #998
                Closed
                Implement SEP-2352: Clarify authorization server binding and migration#879
                #998
                Labels
                2026-07-28P2Medium: important but non-blocking improvementT-enhancementNew features and enhancementsT-securitySecurity-related changesT-transportTransport layer changes
                Milestone
                2026-07-28 spec
                Description
                @alexhancock
                alexhancock
                opened on Jun 2, 2026
                SEP-2352: Clarify authorization server binding and migration — rust-sdk implementation
                Spec PR:modelcontextprotocol/modelcontextprotocol#2352
                Track: Specification · Stage: accepted · Priority: P0 · Theme: Enterprise Readiness
                Needs code changes: Yes (Medium)
                Summary
                Multi-AS guidance:
                • Clients SHOULD maintain separate registration state per authorization server and MUST NOT assume cross-AS credential validity.
                • New "Authorization Server Binding" rules: DCR / pre-registered credentials must be keyed by issuer; CIMD client_ids are portable; clients should error on AS mismatch.
                Why this needs code changes in rust-sdk
                The OAuth client in crates/rmcp/src/transport/auth.rs persists credentials and registration state
                
via the CredentialStore trait (StoredCredentials, InMemoryCredentialStore) and the
                StateStore trait (StoredAuthorizationState, InMemoryStateStore). Today these are effectively
                single-AS: StoredCredentials and the in-memory stores are not keyed by issuer, and
                AuthorizationManager holds one metadata: Option<AuthorizationMetadata> (whose issuer field
                
exists but isn't used to partition stored credentials). So credentials from one AS could be reused
                
against another, which SEP-2352 forbids.
                Proposed work
                •  Key CredentialStore / StateStore entries by issuer — either add an issuer discriminator to StoredCredentials / load/save keys, or make the in-memory stores HashMap<issuer, …> so per-AS state is isolated.
                •  On token use, compare the active AuthorizationMetadata.issuer against the issuer the stored credentials were minted for; on mismatch return a clear AuthError (add a variant, e.g. AuthError::AuthorizationServerMismatch).
                •  Treat CIMD client_ids as portable (don't tie those to a single issuer), but keep DCR/pre-registered credentials issuer-bound.
                •  Update register_client / configure_client_id / get_credentials paths to read/write the issuer-keyed store.
                •  Add tests: two ASes with distinct registrations don't cross-contaminate; mismatch is rejected.
                Affected areas
                crates/rmcp/src/transport/auth.rs (CredentialStore/StoredCredentials, StateStore/StoredAuthorizationState, InMemory*Store, AuthorizationManager, AuthError).
                Notes / risks
                • Part of the Enterprise Readiness auth cluster (837, 2350, 2351, 2468). Bundle into one auth PR/effort to share test scaffolding.
                Metadata
                Metadata
                Assignees
                No one assigned
                  Labels
                  2026-07-28P2Medium: important but non-blocking improvementT-enhancementNew features and enhancementsT-securitySecurity-related changesT-transportTransport layer changes
                  Type
                  No type
                  Projects
                  Milestone
                  Relationships
                  None yet
                  Development
                  No branches or pull requests
                  Issue actions