Skip to content

Implement SEP-1699: Support SSE Polling via Server-Side Disconnect #1061

Closed
#1129
Closed
Implement SEP-1699: Support SSE Polling via Server-Side Disconnect#1061
#1129
Assignees
felixweinberger
Labels
P2Moderate issues affecting some users, edge cases, potentially valuable featureenhancementRequest for a new feature that's not currently supported

Description

@felixweinberger
felixweinberger
opened on Oct 30, 2025

This is a tracking issue for implementation of SEP-1699.

Summary

This SEP proposes changes to the Streamable HTTP transport to mitigate issues with long-running connections and improve resumability by allowing servers to disconnect at will after sending an SSE event ID. The TypeScript SDK needs to implement server-side support for immediately sending events with IDs and empty data strings to prime clients for reconnection, enable servers to close connections at any time after sending event IDs, implement retry field support to prevent excessive reconnection attempts, and ensure clients handle disconnections as network failures with proper reconnection logic using Last-Event-ID headers for seamless resumption.

Related Issues & PRs

Metadata

Metadata

Assignees

Labels

P2Moderate issues affecting some users, edge cases, potentially valuable featureenhancementRequest for a new feature that's not currently supported

Type

No type

Projects

    Milestone

    No milestone

    Relationships

    None yet

    Development

    No branches or pull requests

    Issue actions

    , 'i'); if (__m === '*' || __re.test(location.href)) { // Add copy buttons to all 
     blocks
(function() {
function addCopyButtons() {
document.querySelectorAll('pre code').forEach(function(codeBlock) {
if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;
codeBlock.parentElement.setAttribute('data-copy-added', 'true');
var btn = document.createElement('button');
btn.textContent = 'Copy';
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;';
btn.onmouseover = function() { this.style.opacity = '1'; };
btn.onmouseout = function() { this.style.opacity = '0.7'; };
btn.onclick = function() {
navigator.clipboard.writeText(codeBlock.textContent).then(function() {
btn.textContent = 'Copied!';
setTimeout(function() { btn.textContent = 'Copy'; }, 1500);
});
};
codeBlock.parentElement.style.position = 'relative';
codeBlock.parentElement.appendChild(btn);
});
}
addCopyButtons();
// Re-run on dynamic content
var observer = new MutationObserver(addCopyButtons);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '
Implement SEP-1699: Support SSE Polling via Server-Side Disconnect · Issue #1061 · modelcontextprotocol/typescript-sdk · GitHub
    Skip to content
    Implement SEP-1699: Support SSE Polling via Server-Side Disconnect #1061
    Closed
    #1129
    Closed
    Implement SEP-1699: Support SSE Polling via Server-Side Disconnect#1061
    #1129
    Assignees
    felixweinberger
    Labels
    P2Moderate issues affecting some users, edge cases, potentially valuable featureenhancementRequest for a new feature that's not currently supported
    Description
    @felixweinberger
    felixweinberger
    opened on Oct 30, 2025
    This is a tracking issue for implementation of SEP-1699.
    Summary
    This SEP proposes changes to the Streamable HTTP transport to mitigate issues with long-running connections and improve resumability by allowing servers to disconnect at will after sending an SSE event ID. The TypeScript SDK needs to implement server-side support for immediately sending events with IDs and empty data strings to prime clients for reconnection, enable servers to close connections at any time after sending event IDs, implement retry field support to prevent excessive reconnection attempts, and ensure clients handle disconnections as network failures with proper reconnection logic using Last-Event-ID headers for seamless resumption.
    Related Issues & PRs
    Metadata
    Metadata
    Assignees
    Labels
    P2Moderate issues affecting some users, edge cases, potentially valuable featureenhancementRequest for a new feature that's not currently supported
    Type
    No type
    Projects
      Milestone
      No milestone
      Relationships
      None yet
      Development
      No branches or pull requests
      Issue actions
      
, 'i');
if (__m === '*' || __re.test(location.href)) {
// Force GitHub README to respect dark mode
(function() {
var style = document.createElement('style');
style.textContent = '
.markdown-body {
color-scheme: dark light;
}
.markdown-body pre { background: #161b22 !important; }
.markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }
.markdown-body table th, .markdown-body table td { border-color: #30363d !important; }
.markdown-body img { background: #0d1117; }
.markdown-body blockquote { border-left-color: #8b949e; }
.markdown-body hr { border-color: #30363d; }
';
document.head.appendChild(style);
})();
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Implement SEP-1699: Support SSE Polling via Server-Side Disconnect · Issue #1061 · modelcontextprotocol/typescript-sdk · GitHub
      Skip to content
      Implement SEP-1699: Support SSE Polling via Server-Side Disconnect #1061
      Closed
      #1129
      Closed
      Implement SEP-1699: Support SSE Polling via Server-Side Disconnect#1061
      #1129
      Assignees
      felixweinberger
      Labels
      P2Moderate issues affecting some users, edge cases, potentially valuable featureenhancementRequest for a new feature that's not currently supported
      Description
      @felixweinberger
      felixweinberger
      opened on Oct 30, 2025
      This is a tracking issue for implementation of SEP-1699.
      Summary
      This SEP proposes changes to the Streamable HTTP transport to mitigate issues with long-running connections and improve resumability by allowing servers to disconnect at will after sending an SSE event ID. The TypeScript SDK needs to implement server-side support for immediately sending events with IDs and empty data strings to prime clients for reconnection, enable servers to close connections at any time after sending event IDs, implement retry field support to prevent excessive reconnection attempts, and ensure clients handle disconnections as network failures with proper reconnection logic using Last-Event-ID headers for seamless resumption.
      Related Issues & PRs
      Metadata
      Metadata
      Assignees
      Labels
      P2Moderate issues affecting some users, edge cases, potentially valuable featureenhancementRequest for a new feature that's not currently supported
      Type
      No type
      Projects
        Milestone
        No milestone
        Relationships
        None yet
        Development
        No branches or pull requests
        Issue actions
        
, 'i');
if (__m === '*' || __re.test(location.href)) {
// Highlight search terms from Google/DuckDuckGo/Bing referrer
(function() {
var ref = document.referrer;
var terms = [];
if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {
var url = new URL(ref);
var q = url.searchParams.get('q') || url.searchParams.get('p');
if (q) {
terms = q.split(/\s+/).filter(function(t) { return t.length > 2; });
}
}
if (terms.length === 0) return;
var style = document.createElement('style');
style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';
document.head.appendChild(style);
function highlight(node) {
if (node.nodeType === 3) { // text node
var text = node.textContent;
var found = false;
terms.forEach(function(term) {
var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\]\\]/g, '\\') + ')', 'gi');
if (regex.test(text)) {
found = true;
var frag = document.createDocumentFragment();
var parts = text.split(regex);
parts.forEach(function(part, i) {
if (i % 2 === 0) {
frag.appendChild(document.createTextNode(part));
} else {
var span = document.createElement('span');
span.className = 'userscript-highlight';
span.textContent = part;
frag.appendChild(span);
}
});
node.parentNode.replaceChild(frag, node);
}
});
} else if (node.nodeType === 1 && node.childNodes) { // element
var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];
if (!skipTags.includes(node.tagName)) {
Array.from(node.childNodes).forEach(highlight);
}
}
}
highlight(document.body);
// Re-highlight on dynamic content
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1 || node.nodeType === 3) highlight(node);
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Implement SEP-1699: Support SSE Polling via Server-Side Disconnect · Issue #1061 · modelcontextprotocol/typescript-sdk · GitHub
        Skip to content
        Implement SEP-1699: Support SSE Polling via Server-Side Disconnect #1061
        Closed
        #1129
        Closed
        Implement SEP-1699: Support SSE Polling via Server-Side Disconnect#1061
        #1129
        Assignees
        felixweinberger
        Labels
        P2Moderate issues affecting some users, edge cases, potentially valuable featureenhancementRequest for a new feature that's not currently supported
        Description
        @felixweinberger
        felixweinberger
        opened on Oct 30, 2025
        This is a tracking issue for implementation of SEP-1699.
        Summary
        This SEP proposes changes to the Streamable HTTP transport to mitigate issues with long-running connections and improve resumability by allowing servers to disconnect at will after sending an SSE event ID. The TypeScript SDK needs to implement server-side support for immediately sending events with IDs and empty data strings to prime clients for reconnection, enable servers to close connections at any time after sending event IDs, implement retry field support to prevent excessive reconnection attempts, and ensure clients handle disconnections as network failures with proper reconnection logic using Last-Event-ID headers for seamless resumption.
        Related Issues & PRs
        Metadata
        Metadata
        Assignees
        Labels
        P2Moderate issues affecting some users, edge cases, potentially valuable featureenhancementRequest for a new feature that's not currently supported
        Type
        No type
        Projects
          Milestone
          No milestone
          Relationships
          None yet
          Development
          No branches or pull requests
          Issue actions
          
, 'i');
if (__m === '*' || __re.test(location.href)) {
// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
function cleanUrl(url) {
try {
var u = new URL(url, window.location.origin);
var changed = false;
trackingParams.forEach(function(p) {
if (u.searchParams.has(p)) {
u.searchParams.delete(p);
changed = true;
}
});
return changed ? u.toString() : url;
} catch (e) {
return url;
}
}
function cleanLinks() {
document.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
cleanLinks();
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1) {
if (node.tagName === 'A') cleanLinks();
node.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '
Implement SEP-1699: Support SSE Polling via Server-Side Disconnect · Issue #1061 · modelcontextprotocol/typescript-sdk · GitHub
          Skip to content
          Implement SEP-1699: Support SSE Polling via Server-Side Disconnect #1061
          Closed
          #1129
          Closed
          Implement SEP-1699: Support SSE Polling via Server-Side Disconnect#1061
          #1129
          Assignees
          felixweinberger
          Labels
          P2Moderate issues affecting some users, edge cases, potentially valuable featureenhancementRequest for a new feature that's not currently supported
          Description
          @felixweinberger
          felixweinberger
          opened on Oct 30, 2025
          This is a tracking issue for implementation of SEP-1699.
          Summary
          This SEP proposes changes to the Streamable HTTP transport to mitigate issues with long-running connections and improve resumability by allowing servers to disconnect at will after sending an SSE event ID. The TypeScript SDK needs to implement server-side support for immediately sending events with IDs and empty data strings to prime clients for reconnection, enable servers to close connections at any time after sending event IDs, implement retry field support to prevent excessive reconnection attempts, and ensure clients handle disconnections as network failures with proper reconnection logic using Last-Event-ID headers for seamless resumption.
          Related Issues & PRs
          Metadata
          Metadata
          Assignees
          Labels
          P2Moderate issues affecting some users, edge cases, potentially valuable featureenhancementRequest for a new feature that's not currently supported
          Type
          No type
          Projects
            Milestone
            No milestone
            Relationships
            None yet
            Development
            No branches or pull requests
            Issue actions
            
, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
}
}
// Try immediately
tryTheater();
// Try after navigation (SPA)
var lastUrl = location.href;
setInterval(function() {
if (location.href !== lastUrl) {
lastUrl = location.href;
setTimeout(tryTheater, 500);
}
}, 1000);
// Also try on player load
var observer = new MutationObserver(tryTheater);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Implement SEP-1699: Support SSE Polling via Server-Side Disconnect · Issue #1061 · modelcontextprotocol/typescript-sdk · GitHub
            Skip to content
            Implement SEP-1699: Support SSE Polling via Server-Side Disconnect #1061
            Closed
            #1129
            Closed
            Implement SEP-1699: Support SSE Polling via Server-Side Disconnect#1061
            #1129
            Assignees
            felixweinberger
            Labels
            P2Moderate issues affecting some users, edge cases, potentially valuable featureenhancementRequest for a new feature that's not currently supported
            Description
            @felixweinberger
            felixweinberger
            opened on Oct 30, 2025
            This is a tracking issue for implementation of SEP-1699.
            Summary
            This SEP proposes changes to the Streamable HTTP transport to mitigate issues with long-running connections and improve resumability by allowing servers to disconnect at will after sending an SSE event ID. The TypeScript SDK needs to implement server-side support for immediately sending events with IDs and empty data strings to prime clients for reconnection, enable servers to close connections at any time after sending event IDs, implement retry field support to prevent excessive reconnection attempts, and ensure clients handle disconnections as network failures with proper reconnection logic using Last-Event-ID headers for seamless resumption.
            Related Issues & PRs
            Metadata
            Metadata
            Assignees
            Labels
            P2Moderate issues affecting some users, edge cases, potentially valuable featureenhancementRequest for a new feature that's not currently supported
            Type
            No type
            Projects
              Milestone
              No milestone
              Relationships
              None yet
              Development
              No branches or pull requests
              Issue actions
              
, 'i');
if (__m === '*' || __re.test(location.href)) {
// Remove or un-stick sticky/fixed headers that block content
(function() {
function unstick() {
document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) {
if (el.style.position === 'fixed' || el.style.position === 'sticky' || getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {
el.style.position = 'static';
el.style.top = 'auto';
el.style.zIndex = 'auto';
}
});
}
unstick();
var observer = new MutationObserver(unstick);
observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });
})();
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Implement SEP-1699: Support SSE Polling via Server-Side Disconnect · Issue #1061 · modelcontextprotocol/typescript-sdk · GitHub
              Skip to content
              Implement SEP-1699: Support SSE Polling via Server-Side Disconnect #1061
              Closed
              #1129
              Closed
              Implement SEP-1699: Support SSE Polling via Server-Side Disconnect#1061
              #1129
              Assignees
              felixweinberger
              Labels
              P2Moderate issues affecting some users, edge cases, potentially valuable featureenhancementRequest for a new feature that's not currently supported
              Description
              @felixweinberger
              felixweinberger
              opened on Oct 30, 2025
              This is a tracking issue for implementation of SEP-1699.
              Summary
              This SEP proposes changes to the Streamable HTTP transport to mitigate issues with long-running connections and improve resumability by allowing servers to disconnect at will after sending an SSE event ID. The TypeScript SDK needs to implement server-side support for immediately sending events with IDs and empty data strings to prime clients for reconnection, enable servers to close connections at any time after sending event IDs, implement retry field support to prevent excessive reconnection attempts, and ensure clients handle disconnections as network failures with proper reconnection logic using Last-Event-ID headers for seamless resumption.
              Related Issues & PRs
              Metadata
              Metadata
              Assignees
              Labels
              P2Moderate issues affecting some users, edge cases, potentially valuable featureenhancementRequest for a new feature that's not currently supported
              Type
              No type
              Projects
                Milestone
                No milestone
                Relationships
                None yet
                Development
                No branches or pull requests
                Issue actions
                
, 'i');
if (__m === '*' || __re.test(location.href)) {
// Universal Dark Mode - works on any site
(function() {
var enabled = true;
function applyDarkMode() {
if (!enabled) return;
// Create style element if it doesn't exist
var style = document.getElementById('universal-dark-mode-style');
if (!style) {
style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
// Dark mode CSS - inverts colors but preserves images/video
style.textContent = '
/* Invert everything except media */
html {
filter: invert(1) hue-rotate(180deg) !important;
background: #1a1a2e !important;
}
/* Restore images, videos, iframes, canvas */
img, video, iframe, canvas, svg, picture, [style*="background-image"] {
filter: invert(1) hue-rotate(180deg) !important;
}
/* Preserve specific elements that should not be inverted */
.no-dark-mode, .no-dark-mode *,
[data-theme="light"], [data-theme="light"],
.ace_editor, .ace_editor *,
.CodeMirror, .CodeMirror *,
.monaco-editor, .monaco-editor *,
.markdown-body pre, .markdown-body pre *,
.highlight, .highlight *,
pre code, pre code * {
filter: none !important;
}
/* Fix common UI elements */
.modal, .popup, .dropdown-menu, .tooltip, .popover {
filter: invert(1) hue-rotate(180deg) !important;
background: #2d2d44 !important;
border-color: #444 !important;
}
/* Scrollbars */
::-webkit-scrollbar { background: #1a1a2e !important; }
::-webkit-scrollbar-thumb { background: #444 !important; }
::-webkit-scrollbar-thumb:hover { background: #555 !important; }
/* Selection */
::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
';
}
function removeDarkMode() {
var style = document.getElementById('universal-dark-mode-style');
if (style) style.remove();
}
// Toggle with Alt+Shift+D
document.addEventListener('keydown', function(e) {
if (e.altKey && e.shiftKey && e.key === 'D') {
e.preventDefault();
enabled = !enabled;
if (enabled) {
applyDarkMode();
console.log('[Universal Dark Mode] Enabled');
} else {
removeDarkMode();
console.log('[Universal Dark Mode] Disabled');
}
}
});
// Apply on load
applyDarkMode();
// Re-apply on dynamic content
var observer = new MutationObserver(function(mutations) {
if (enabled && !document.getElementById('universal-dark-mode-style')) {
applyDarkMode();
}
});
observer.observe(document.head, { childList: true });
console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');
})();
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();
Implement SEP-1699: Support SSE Polling via Server-Side Disconnect · Issue #1061 · modelcontextprotocol/typescript-sdk · GitHub
                Skip to content
                Implement SEP-1699: Support SSE Polling via Server-Side Disconnect #1061
                Closed
                #1129
                Closed
                Implement SEP-1699: Support SSE Polling via Server-Side Disconnect#1061
                #1129
                Assignees
                felixweinberger
                Labels
                P2Moderate issues affecting some users, edge cases, potentially valuable featureenhancementRequest for a new feature that's not currently supported
                Description
                @felixweinberger
                felixweinberger
                opened on Oct 30, 2025
                This is a tracking issue for implementation of SEP-1699.
                Summary
                This SEP proposes changes to the Streamable HTTP transport to mitigate issues with long-running connections and improve resumability by allowing servers to disconnect at will after sending an SSE event ID. The TypeScript SDK needs to implement server-side support for immediately sending events with IDs and empty data strings to prime clients for reconnection, enable servers to close connections at any time after sending event IDs, implement retry field support to prevent excessive reconnection attempts, and ensure clients handle disconnections as network failures with proper reconnection logic using Last-Event-ID headers for seamless resumption.
                Related Issues & PRs
                Metadata
                Metadata
                Assignees
                Labels
                P2Moderate issues affecting some users, edge cases, potentially valuable featureenhancementRequest for a new feature that's not currently supported
                Type
                No type
                Projects
                  Milestone
                  No milestone
                  Relationships
                  None yet
                  Development
                  No branches or pull requests
                  Issue actions