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Add support for custom middleware in the correct order. #2026

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Merged
omgitsads merged 3 commits into from
Feb 18, 2026
Merged

Add support for custom middleware in the correct order. #2026

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2824a8f
Add support for custom middleware in the correct order.
omgitsads Feb 17, 2026
28b8d19
Switch this up to be more clear on what it's doing
omgitsads Feb 18, 2026
ee4da8d
Merge branch 'main' into support-custom-middleware
omgitsads Feb 18, 2026
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8 changes: 5 additions & 3 deletions pkg/github/server.go
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Original file line number Diff line number Diff line change
Expand Up @@ -73,7 +73,7 @@ type MCPServerConfig struct {

type MCPServerOption func(*mcp.ServerOptions)

func NewMCPServer(ctx context.Context, cfg *MCPServerConfig, deps ToolDependencies, inv *inventory.Inventory) (*mcp.Server, error) {
func NewMCPServer(ctx context.Context, cfg *MCPServerConfig, deps ToolDependencies, inv *inventory.Inventory, middleware ...mcp.Middleware) (*mcp.Server, error) {
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Copilot AI Feb 18, 2026

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Consider adding test coverage for the new middleware parameter to verify that custom middleware is executed in the correct order relative to the default middlewares (error context and deps injection). A test could verify that custom middleware can successfully read errors from the context that were set by tools/handlers, confirming the middleware chain works as intended.

This issue also appears on line 101 of the same file.

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// Create the MCP server
serverOpts := &mcp.ServerOptions{
Instructions: inv.Instructions(),
Expand All @@ -98,9 +98,11 @@ func NewMCPServer(ctx context.Context, cfg *MCPServerConfig, deps ToolDependenci

ghServer := NewServer(cfg.Version, serverOpts)

// Add middlewares
ghServer.AddReceivingMiddleware(addGitHubAPIErrorToContext)
// Add middlewares. Order matters - for example, the error context middleware should be applied last so that it runs FIRST (closest to the handler) to ensure all errors are captured,
// and any middleware that needs to read or modify the context should be before it.
ghServer.AddReceivingMiddleware(middleware...)
ghServer.AddReceivingMiddleware(InjectDepsMiddleware(deps))
ghServer.AddReceivingMiddleware(addGitHubAPIErrorToContext)

if unrecognized := inv.UnrecognizedToolsets(); len(unrecognized) > 0 {
cfg.Logger.Warn("Warning: unrecognized toolsets ignored", "toolsets", strings.Join(unrecognized, ", "))
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3 changes: 3 additions & 0 deletions pkg/http/handler.go
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Expand Up @@ -19,6 +19,9 @@ import (
)

type InventoryFactoryFunc func(r *http.Request) (*inventory.Inventory, error)

// GitHubMCPServerFactoryFunc is a function type for creating a new MCP Server instance.
// middleware are applied AFTER the default GitHub MCP Server middlewares (like error context injection)
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Copilot AI Feb 18, 2026

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The comment "middleware are applied AFTER the default GitHub MCP Server middlewares" is ambiguous. "Applied AFTER" could be interpreted as "added to the stack after" or "executed after". Based on the code, custom middleware is added first (line 103) but executes after the default middlewares have set up the context. Consider clarifying: "middleware will execute after the default middlewares (error context, deps injection) have set up the request context, allowing them to read errors and dependencies set by the defaults".

Suggested change
// middleware are applied AFTER the default GitHub MCP Server middlewares (like error context injection)
// Custom middleware created via this factory will execute after the default GitHub MCP Server
// middlewares (such as error context and dependency injection) have populated the request context,
// allowing the custom middleware to read errors and dependencies set by the defaults.

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type GitHubMCPServerFactoryFunc func(r *http.Request, deps github.ToolDependencies, inventory *inventory.Inventory, cfg *github.MCPServerConfig) (*mcp.Server, error)

type Handler struct {
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