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mcp: add lastEventIDHeader for streamable implementation

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Use a constant, to be consistent with other headers.
This commit is contained in:
Rob Findley 2025-12-06 19:13:57 -05:00 • committed by Robert Findley
commit b8c21e9fc0
1 changed files with 5 additions and 4 deletions
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9
mcp/streamable.go
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@ -32,6 +32,7 @@ import (
const ( const (
protocolVersionHeader = "Mcp-Protocol-Version" protocolVersionHeader = "Mcp-Protocol-Version"
sessionIDHeader = "Mcp-Session-Id" sessionIDHeader = "Mcp-Session-Id"
lastEventIDHeader = "Last-Event-ID"
) )
// A StreamableHTTPHandler is an http.Handler that serves streamable MCP // A StreamableHTTPHandler is an http.Handler that serves streamable MCP
@ -713,8 +714,8 @@ func (c *streamableServerConn) serveGET(w http.ResponseWriter, req *http.Request
// By default, we haven't seen a last index. Since indices start at 0, we represent // By default, we haven't seen a last index. Since indices start at 0, we represent
// that by -1. This is incremented just before each event is written. // that by -1. This is incremented just before each event is written.
lastIdx := -1 lastIdx := -1
if len(req.Header.Values("Last-Event-ID")) > 0 { if len(req.Header.Values(lastEventIDHeader)) > 0 {
eid := req.Header.Get("Last-Event-ID") eid := req.Header.Get(lastEventIDHeader)
var ok bool var ok bool
streamID, lastIdx, ok = parseEventID(eid) streamID, lastIdx, ok = parseEventID(eid)
if !ok { if !ok {
@ -931,7 +932,7 @@ func (c *streamableServerConn) acquireStream(ctx context.Context, w http.Respons
// //
// It returns an HTTP status code and error message. // It returns an HTTP status code and error message.
func (c *streamableServerConn) servePOST(w http.ResponseWriter, req *http.Request) { func (c *streamableServerConn) servePOST(w http.ResponseWriter, req *http.Request) {
if len(req.Header.Values("Last-Event-ID")) > 0 { if len(req.Header.Values(lastEventIDHeader)) > 0 {
http.Error(w, "can't send Last-Event-ID for POST request", http.StatusBadRequest) http.Error(w, "can't send Last-Event-ID for POST request", http.StatusBadRequest)
return return
} }
@ -1923,7 +1924,7 @@ func (c *streamableClientConn) connectSSE(ctx context.Context, lastEventID strin
} }
c.setMCPHeaders(req) c.setMCPHeaders(req)
if lastEventID != "" { if lastEventID != "" {
req.Header.Set("Last-Event-ID", lastEventID) req.Header.Set(lastEventIDHeader, lastEventID)
} }
req.Header.Set("Accept", "text/event-stream") req.Header.Set("Accept", "text/event-stream")
resp, err := c.client.Do(req) resp, err := c.client.Do(req)