refactor: deduplicate reconnect telemetry and SSE deprecation logging in connection.go (#3660)

Three duplicate logging patterns in `internal/mcp/connection.go` created
maintainability risk: reconnect lifecycle logs were copy-pasted verbatim
across two sibling functions, and SSE deprecation connected with a
5-line near-identical warning burst.

## Changes

- **Reconnect telemetry helpers** — extracted `logReconnectStart()` and
`logReconnectResult(err error)` methods; both `reconnectPlainJSON()` and
`reconnectSDKTransport()` now delegate to them instead of duplicating
three `logger.Log*` call sites each:

  ```go
  func (c *Connection) logReconnectStart() {
logger.LogWarn("backend", "MCP session expired for %s, attempting to
reconnect...", c.serverID)
  }
  func (c *Connection) logReconnectResult(err error) {
      if err != nil {
logger.LogError("backend", "Session reconnect failed for %s: %v",
c.serverID, err)
      } else {
logger.LogInfo("backend", "Session successfully reconnected for %s",
c.serverID)
      }
  }
  ```

- **SSE deprecation warning** — collapsed 5 overlapping `LogWarn` calls
(all saying "SSE is deprecated, please migrate") into one `LogWarn` with
the URL + spec version, plus one `LogInfo` for the connection
confirmation. Issue #3633 (redundant `log.Printf` / `logger.LogInfo`
pairs) was already resolved prior to this PR.

> [!WARNING]
>
> <details>
> <summary>Firewall rules blocked me from connecting to one or more
addresses (expand for details)</summary>
>
> #### I tried to connect to the following addresses, but was blocked by
firewall rules:
>
> - `example.com`
> - Triggering command: `/tmp/go-build3844589215/b514/launcher.test
/tmp/go-build3844589215/b514/launcher.test
-test.testlogfile=/tmp/go-build3844589215/b514/testlog.txt
-test.paniconexit0 -test.timeout=10m0s -W .cfg
elemetry.io/otel-ifaceassert x_amd64/vet
ache/go/1.25.8/x/usr/libexec/docker/cli-plugins/docker-compose --gdwarf2
--64 x_amd64/vet -I .cfg om/yosida95/uritemplate/v3@v3.0.2/equals.go
x_amd64/vet --gdwarf-5 g/protobuf/inter--version -o x_amd64/vet` (dns
block)
> - `https://api.github.com/graphql`
> - Triggering command: `/usr/bin/gh gh issue close 3634 --comment Fixed
in PR #3660: Consolidated the 5-line SSE deprecation warning burst into
2 concise log calls ��� one `LogWarn` containing the URL, spec version,
and migration ask, and one `LogInfo` confirming the connection. This
eliminates the near-duplicate messag ock

- Extract logReconnectStart() and logReconnectResult(err) helpers to
  deduplicate the three identical logger.Log* call sites shared by
  reconnectPlainJSON() and reconne` (http block)
> - Triggering command: `/usr/bin/gh gh issue close 3632 --comment Fixed
in PR #3660: Extracted `logReconnectStart()` and
`logReconnectResult(err)` helper methods into `connection.go`. Both
`reconnectPlainJSON()` and `reconnectSDKTransport()` now delegate their
three shared `logger.Log*` call sites to these helpers, elim
iVcYPCLQvuKP by/fbd8401427f0fc669ca1ec4ad2768json D8KssBkgN
059210538/b288///opt/hostedtoolcache/CodeQL/2.25.1/x64/codeql/go/tools/autobuild.sh`
(http block)
> - Triggering command: `/usr/bin/gh gh issue comment 3634 --body Fixed
in PR #3660: Consolidated the 5-line SSE deprecation warning burst into
2 concise log calls ��� one `LogWarn` containing the URL, spec version,
and migration ask, and one `LogInfo` confirming the connection. --repo
github/gh-aw-mcpg ntime.v2.task/mogit om/tetratelabs/w-c x_amd64/vet
egration/start_glog 4589�� .go y /bin/java ntime.v2.task/mogit
rg/x/net@v0.52.0add x_amd64/vet /bin/java` (http block)
> - `invalid-host-that-does-not-exist-12345.com`
> - Triggering command: `/tmp/go-build3844589215/b496/config.test
/tmp/go-build3844589215/b496/config.test
-test.testlogfile=/tmp/go-build3844589215/b496/testlog.txt
-test.paniconexit0 -test.timeout=10m0s
/tmp/go-build3844589215/b396/vet.cfg @v1.1.3/cpu/cpu.-errorsas
om/tetratelabs/w-ifaceassert x_amd64/vet --gdwarf-5
nal/encoding/def-atomic -o x_amd64/vet -I hB8eipdrZ -I x_amd64/vet
--gdwarf-5 9210538/b239/ -o x_amd64/vet` (dns block)
> - `nonexistent.local`
> - Triggering command: `/tmp/go-build3844589215/b514/launcher.test
/tmp/go-build3844589215/b514/launcher.test
-test.testlogfile=/tmp/go-build3844589215/b514/testlog.txt
-test.paniconexit0 -test.timeout=10m0s -W .cfg
elemetry.io/otel-ifaceassert x_amd64/vet
ache/go/1.25.8/x/usr/libexec/docker/cli-plugins/docker-compose --gdwarf2
--64 x_amd64/vet -I .cfg om/yosida95/uritemplate/v3@v3.0.2/equals.go
x_amd64/vet --gdwarf-5 g/protobuf/inter--version -o x_amd64/vet` (dns
block)
> - `slow.example.com`
> - Triggering command: `/tmp/go-build3844589215/b514/launcher.test
/tmp/go-build3844589215/b514/launcher.test
-test.testlogfile=/tmp/go-build3844589215/b514/testlog.txt
-test.paniconexit0 -test.timeout=10m0s -W .cfg
elemetry.io/otel-ifaceassert x_amd64/vet
ache/go/1.25.8/x/usr/libexec/docker/cli-plugins/docker-compose --gdwarf2
--64 x_amd64/vet -I .cfg om/yosida95/uritemplate/v3@v3.0.2/equals.go
x_amd64/vet --gdwarf-5 g/protobuf/inter--version -o x_amd64/vet` (dns
block)
> - `this-host-does-not-exist-12345.com`
> - Triggering command: `/tmp/go-build3844589215/b523/mcp.test
/tmp/go-build3844589215/b523/mcp.test
-test.testlogfile=/tmp/go-build3844589215/b523/testlog.txt
-test.paniconexit0 -test.timeout=10m0s
/tmp/go-build3844589215/b517/_pkg_.a 64/src/os/signal/sig.s -I
x_amd64/vet --gdwarf-5 g/grpc/credentiainspect -o x_amd64/vet -W
/auth/apikey.go /auth/header.go x_amd64/vet . --gdwarf2 --64
x_amd64/vet` (dns block)
>
> If you need me to access, download, or install something from one of
these locations, you can either:
>
> - Configure [Actions setup
steps](https://gh.io/copilot/actions-setup-steps) to set up my
environment, which run before the firewall is enabled
> - Add the appropriate URLs or hosts to the custom allowlist in this
repository's [Copilot coding agent
settings](https://github.com/github/gh-aw-mcpg/settings/copilot/coding_agent)
(admins only)
>
> </details>

Author: lpcox

internal/mcp/connection.go

@@ -243,11 +243,8 @@ func NewHTTPConnection(ctx context.Context, serverID, url string, headers map[st
 	logConn.Printf("Attempting SSE transport for %s", url)
 	conn, err = trySSETransport(ctx, cancel, serverID, url, headers, headerClient, keepAlive)
 	if err == nil {
-		logger.LogWarn("backend", "⚠️  MCP over SSE has been deprecated. Connected using SSE transport for url=%s. Please migrate to streamable HTTP transport (2025-03-26 spec).", url)
-		logger.LogWarn("backend", "⚠️  WARNING: MCP over SSE (2024-11-05 spec) has been DEPRECATED")
-		logger.LogWarn("backend", "⚠️  The server at %s is using the deprecated SSE transport", url)
-		logger.LogWarn("backend", "⚠️  Please migrate to streamable HTTP transport (2025-03-26 spec)")
-		logger.LogWarn("backend", "Configured HTTP MCP server with SSE transport: %s", url)
+		logger.LogWarn("backend", "⚠️  MCP over SSE (2024-11-05 spec) is DEPRECATED for url=%s. Please migrate to streamable HTTP transport (2025-03-26 spec).", url)
+		logger.LogInfo("backend", "Configured HTTP MCP server with SSE transport: %s", url)
 		return conn, nil
 	}
 	logConn.Printf("SSE transport failed: %v", err)
@@ -296,6 +293,21 @@ func (c *Connection) ServerInfo() (name, version string) {
 	return initResult.ServerInfo.Name, initResult.ServerInfo.Version
 }
 
+// logReconnectStart emits the structured log warning that is common to all reconnect paths.
+func (c *Connection) logReconnectStart() {
+	logger.LogWarn("backend", "MCP session expired for %s, attempting to reconnect...", c.serverID)
+}
+
+// logReconnectResult emits the structured log entry that signals whether the reconnect
+// succeeded or failed. It is the common success/failure telemetry shared by all reconnect paths.
+func (c *Connection) logReconnectResult(err error) {
+	if err != nil {
+		logger.LogError("backend", "Session reconnect failed for %s: %v", c.serverID, err)
+	} else {
+		logger.LogInfo("backend", "Session successfully reconnected for %s", c.serverID)
+	}
+}
+
 // reconnectPlainJSON re-initialises the plain JSON-RPC session with the HTTP backend.
 // It is safe for concurrent callers: only one reconnect runs at a time, and the updated
 // session ID is available to all callers once the lock is released.
@@ -304,17 +316,16 @@ func (c *Connection) reconnectPlainJSON() error {
 	defer c.sessionMu.Unlock()
 
 	logConn.Printf("Session expired, reconnecting plain JSON-RPC for serverID=%s", c.serverID)
-	logger.LogWarn("backend", "MCP session expired for %s, attempting to reconnect...", c.serverID)
+	c.logReconnectStart()
 
 	sessionID, err := c.initializeHTTPSession()
+	c.logReconnectResult(err)
 	if err != nil {
-		logger.LogError("backend", "Session reconnect failed for %s: %v", c.serverID, err)
 		return fmt.Errorf("session reconnect failed: %w", err)
 	}
 
 	c.httpSessionID = sessionID
 	logConn.Printf("Reconnected plain JSON-RPC session for serverID=%s, new sessionID=%s", c.serverID, sessionID)
-	logger.LogInfo("backend", "Session successfully reconnected for %s", c.serverID)
 	return nil
 }
 
@@ -325,7 +336,7 @@ func (c *Connection) reconnectSDKTransport() error {
 	defer c.sessionMu.Unlock()
 
 	logConn.Printf("Session expired, reconnecting SDK transport for serverID=%s, type=%s", c.serverID, c.httpTransportType)
-	logger.LogWarn("backend", "MCP session expired for %s, attempting to reconnect...", c.serverID)
+	c.logReconnectStart()
 
 	// Close the existing session gracefully (ignore error – it's already dead).
 	if c.session != nil {
@@ -359,16 +370,15 @@ func (c *Connection) reconnectSDKTransport() error {
 	defer cancel()
 
 	session, err := client.Connect(connectCtx, transport, nil)
+	c.logReconnectResult(err)
 	if err != nil {
-		logger.LogError("backend", "Session reconnect failed for %s: %v", c.serverID, err)
 		return fmt.Errorf("session reconnect failed: %w", err)
 	}
 
 	c.client = client
 	c.session = session
 
 	logConn.Printf("Reconnected SDK session for serverID=%s", c.serverID)
-	logger.LogInfo("backend", "Session successfully reconnected for %s", c.serverID)
 	return nil
 }