gh cs ssh can hide errors on port forwarding

Describe the bug

When running gh cs ssh we forward the codespaces internal port (16634) in order to connect via GRPC.

Lines 105 to 133 in 4c47bad

    
           // Tunnel the remote gRPC server port to the local port 
        
           go func() { 
        
           	// Start forwarding the port locally 
        
           	opts := portforwarder.ForwardPortOpts{ 
        
           		Port:     codespacesInternalPort, 
        
           		Internal: true, 
        
           	} 
        
           	ch <- fwd.ForwardPortToListener(pfctx, opts, listener) 
        
           }() 
        
           var conn *grpc.ClientConn 
        
           go func() { 
        
           	// Attempt to connect to the port 
        
           	opts := []grpc.DialOption{ 
        
           		grpc.WithTransportCredentials(insecure.NewCredentials()), 
        
           	} 
        
           	conn, err = grpc.NewClient(localAddress, opts...) 
        
           	ch <- err // nil if we successfully connected 
        
           }() 
        
           // Wait for the connection to be established or for the context to be cancelled 
        
           select { 
        
           case <-ctx.Done(): 
        
           	return nil, ctx.Err() 
        
           case err := <-ch: 
        
           	if err != nil { 
        
           		return nil, err 
        
           	} 
        
           }

Both the port forward and the grpc client construction write to ch when completing, then the select unblocks. However, we've seen port forwarding fail but grpc client construction succeed, resulting in a failure much down the line that was not surfaced.

Affected version

➜  gh version
gh version 2.74.2 (2025-06-17)
https://github.com/cli/cli/releases/tag/v2.74.2

Steps to reproduce the behavior

Not possible to produce without a port forwarding issue or code changes.

Apply the following patch and see that the error doesn't bubble up:

diff --git a/internal/codespaces/rpc/invoker.go b/internal/codespaces/rpc/invoker.go
index 6ba8843ac..d1d19e5b9 100644
--- a/internal/codespaces/rpc/invoker.go
+++ b/internal/codespaces/rpc/invoker.go
@@ -5,6 +5,7 @@ package rpc
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"net"
 	"os"
@@ -104,12 +105,8 @@ func connect(ctx context.Context, fwd portforwarder.PortForwarder) (Invoker, err
 
 	// Tunnel the remote gRPC server port to the local port
 	go func() {
-		// Start forwarding the port locally
-		opts := portforwarder.ForwardPortOpts{
-			Port:     codespacesInternalPort,
-			Internal: true,
-		}
-		ch <- fwd.ForwardPortToListener(pfctx, opts, listener)
+		time.Sleep(time.Second)
+		ch <- errors.New("omg")
 	}()
 
 	var conn *grpc.ClientConn

Hi! I’d like to work on this issue. Could you please assign it to me? I’ll make sure to follow the contribution guidelines. Thanks!

fix: surface port-forward errors in codespaces ssh

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`gh cs ssh` can hide errors on port forwarding #11206

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	// Tunnel the remote gRPC server port to the local port
	go func() {
	// Start forwarding the port locally
	opts := portforwarder.ForwardPortOpts{
	Port: codespacesInternalPort,
	Internal: true,
	}
	ch <- fwd.ForwardPortToListener(pfctx, opts, listener)
	}()

	var conn *grpc.ClientConn
	go func() {
	// Attempt to connect to the port
	opts := []grpc.DialOption{
	grpc.WithTransportCredentials(insecure.NewCredentials()),
	}
	conn, err = grpc.NewClient(localAddress, opts...)
	ch <- err // nil if we successfully connected
	}()

	// Wait for the connection to be established or for the context to be cancelled
	select {
	case <-ctx.Done():
	return nil, ctx.Err()
	case err := <-ch:
	if err != nil {
	return nil, err
	}
	}

gh cs ssh can hide errors on port forwarding #11206

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Describe the bug

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Mishra-coder commented on Mar 23, 2026

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`gh cs ssh` can hide errors on port forwarding #11206