Implement Cobra v1.10.0 improvements: context support, declarative flag validation, and lifecycle hooks

[Claude]

Implements Priority 1 and 2 recommendations from Go Fan report for github.com/spf13/cobra v1.10.2. Leverages new Cobra features for cleaner CLI code and better reliability.

Context-based graceful shutdown

Replace manual signal handling with signal.NotifyContext for proper cancellation propagation:

// Before: manual signal channel
ctx, cancel := context.WithCancel(context.Background())
sigChan := make(chan os.Signal, 1)
signal.Notify(sigChan, os.Interrupt, syscall.SIGTERM)

// After: v1.10.0 pattern
ctx, cancel := signal.NotifyContext(cmd.Context(), os.Interrupt, syscall.SIGTERM)

• HTTP server shutdown with 5s timeout via httpServer.Shutdown(ctx)
• Context cancellation propagates through unified server

Declarative flag validation

Replace manual preRun validation with Cobra's built-in validation groups:

// Flag validation groups
cmd.MarkFlagsMutuallyExclusive("routed", "unified")
cmd.MarkFlagsOneRequired("config", "config-stdin")

• Removes 5 lines of manual validation logic from preRun
• Produces consistent error messages: "at least one of the flags in the group [config config-stdin] is required"
• Updates integration test to expect new error format

Lifecycle hooks

• Add PersistentPostRun hook for logger cleanup
• Moves defer calls from run() to postRun() for cleaner separation
• Logger initialization in run, cleanup in postRun

Enhanced completions

Add ActiveHelp hints for better shell completion UX:

cmd.ValidArgsFunction = func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
    return cobra.AppendActiveHelp(nil,
        "Tip: Use --config <file> for file-based config or --config-stdin for piped JSON config"),
        cobra.ShellCompDirectiveNoFileComp
}

Version template

Custom formatting: MCPG Gateway {{.Version}} instead of default output.

Tests

• Context cancellation behavior
• Flag validation group registration
• Version template and postRun hook presence

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• example.com
  • Triggering command: /tmp/go-build884163099/b275/launcher.test /tmp/go-build884163099/b275/launcher.test -test.testlogfile=/tmp/go-build884163099/b275/testlog.txt -test.paniconexit0 -test.timeout=10m0s -test.v=true go 95WK6prK2 x_amd64/vet (dns block)
• invalid-host-that-does-not-exist-12345.com
  • Triggering command: /tmp/go-build884163099/b260/config.test /tmp/go-build884163099/b260/config.test -test.testlogfile=/tmp/go-build884163099/b260/testlog.txt -test.paniconexit0 -test.timeout=10m0s -test.v=true g_.a HEAD 64/bin/as TOKEN"; }; f sto/tmp/go-build3472542465/b223/cmd.test go cal/bin/git 512block_amd64.o-test.timeout=10m0s 64/s�� 64/src/runtime/cgo xpwaXSmNs ache/go/1.25.6/x64/pkg/tool/linu--64 --abbrev-ref 2542465/b013/ .12/x64/bin/git 05.o (dns block)
• nonexistent.local
  • Triggering command: /tmp/go-build884163099/b275/launcher.test /tmp/go-build884163099/b275/launcher.test -test.testlogfile=/tmp/go-build884163099/b275/testlog.txt -test.paniconexit0 -test.timeout=10m0s -test.v=true go 95WK6prK2 x_amd64/vet (dns block)
• slow.example.com
  • Triggering command: /tmp/go-build884163099/b275/launcher.test /tmp/go-build884163099/b275/launcher.test -test.testlogfile=/tmp/go-build884163099/b275/testlog.txt -test.paniconexit0 -test.timeout=10m0s -test.v=true go 95WK6prK2 x_amd64/vet (dns block)
• this-host-does-not-exist-12345.com
  • Triggering command: /tmp/go-build884163099/b284/mcp.test /tmp/go-build884163099/b284/mcp.test -test.testlogfile=/tmp/go-build884163099/b284/testlog.txt -test.paniconexit0 -test.timeout=10m0s -test.v=true g_.a HEAD x_amd64/vet --abbrev-ref /bidi git x_amd64/vet 64/s�� 64/src/runtime/cgo1.25.6 V8YDPttZl inux.go esnew.go ocknew.go nix_cgo.go nix_cgo_res.go (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure 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 (admins only)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[go-fan] Go Module Review: github.com/spf13/cobra</issue_title>
<issue_description># 🐹 Go Fan Report: Cobra CLI Framework

Module Overview

Cobra (github.com/spf13/cobra) is the industry-standard CLI framework for Go, powering tools like kubectl, hugo, and GitHub CLI. It provides a powerful structure for building modern command-line applications with commands, subcommands, flags, and shell completions.

Current Version: v1.10.2 ✅ (Latest: v1.10.2, Dec 3, 2025)
Repository: https://github.com/spf13/cobra
Popularity: 40k+ stars

Current Usage in gh-aw-mcpg

Well-Implemented ✅

The project uses Cobra appropriately across 7 files in internal/cmd/:

Files & Structure

• root.go - Root command definition and CLI entry point
• completion.go - Shell completion commands (bash, zsh, fish, powershell)
• flags.go* (5 files) - Well-organized flag definitions by domain:
  • flags_core.go - Core configuration flags
  • flags_logging.go - Logging flags
  • flags_difc.go - DIFC feature flags (properly uses MarkHidden())
  • flags_launch.go - Launch configuration
  • flags.go - Registration helpers

Key Patterns Observed

✅ Clean command structure without unnecessary nesting
✅ Flags well-organized by functional area
✅ Proper use of MarkHidden() for experimental features
✅ Comprehensive shell completion support
✅ Version command integration

Research Findings

Recent Cobra Updates (v1.10.x)

v1.10.2 (Dec 2025) - Current Version

• Dependency Cleanup: Migrated from deprecated gopkg.in/yaml.v3 to go.yaml.in/yaml/v3
  • Significantly cleaner dependency chain
  • No action required (transparent upgrade)
• Performance improvements (vars → consts)
• Enhanced documentation for repeated flags

v1.10.0 (Sep 2025)

• Context Support: Commands can now receive and use context for cancellation/timeout
• Customizable ShellCompDirective: Per-command completion behavior
• Improved map flag completions

v1.9.0 (Feb 2025)

• Linker Deadcode Elimination: Smaller binaries by removing unused code
• CompletionFunc Type: Cleaner completion code
• CompletionWithDesc Helper: Easier completions with descriptions
• ActiveHelp: Context-sensitive help during tab completion

Best Practices from Cobra Maintainers

1. Error Handling: Use RunE instead of Run to return errors properly
2. Flag Validation: Use built-in flag groups instead of manual validation
3. Context Usage: Pass context to commands for cancellation and timeouts
4. Completions: Implement dynamic completions for better UX
5. Lifecycle Hooks: Use Pre/Post Run hooks for setup and teardown

Improvement Opportunities

🏃 Quick Wins (High Impact, Low Effort)

1. Add Context Support (v1.10.0 feature)

Priority: HIGH | Effort: LOW

Current: No evidence of context usage for graceful shutdown
Opportunity: Enable proper cancellation and timeout handling

// In root.go
ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
defer cancel()
rootCmd.SetContext(ctx)

// In command RunE
func(cmd *cobra.Command, args []string) error {
    ctx := cmd.Context() // Get context with cancellation support
    // Use ctx for HTTP requests, goroutines, etc.
    return server.Run(ctx)
}

Benefits:

• ✅ Proper graceful shutdown on SIGINT/SIGTERM
• ✅ Timeout handling for long-running operations
• ✅ Request tracing and cancellation propagation
• ✅ Better testability with context-based timeouts

2. Use Flag Validation Groups

Priority: HIGH | Effort: LOW

Current: Manual flag validation in code
Opportunity: Declarative validation with better error messages

// Mutually exclusive flags
cmd.MarkFlagsMutuallyExclusive("config", "stdin-config")

// Flags required together
cmd.MarkFlagsRequiredTogether("log-dir", "enable-file-logging")

// At least one required
cmd.MarkFlagsOneRequired("config", "stdin-config")

Benefits:

• ✅ Cleaner code (remove manual validation logic)
• ✅ Consistent, user-friendly error messages
• ✅ Self-documenting flag relationships
• ✅ Less maintenance burden

3. Enhanced Dynamic Completions

Priority: MEDIUM | Effort: MEDIUM

Current: Static shell completions
Opportunity: Dynamic completions for config files, server IDs

// Config file completion
cmd.RegisterFlagCompletionFunc("config", func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
    configs, _ := filepath.Glob("*.toml")
    suggestions := []string{}
    for _, c := range configs {
        suggestions = append(suggestions, c+"\tTOML configuration file")
    }
    return suggestions, cobra.ShellCompDirectiveDefault
})

// Server ID completion (from loaded config)
cmd.RegisterFlagCompletionFunc("server-id", func(cmd *co...

</details>



<!-- START COPILOT CODING AGENT SUFFIX -->

- Fixes github/gh-aw-mcpg#874

[Copilot]

Pull request overview

Updates the CLI’s Cobra integration to take advantage of newer Cobra features (context-aware execution, declarative flag validation, and lifecycle hooks) to improve shutdown behavior and reduce manual validation logic.

Changes:

• Switches graceful shutdown to signal.NotifyContext(cmd.Context(), ...) and adds an HTTP server shutdown timeout.
• Replaces manual --config/--config-stdin validation with Cobra flag validation groups.
• Adds PersistentPostRun cleanup for logger shutdown and enhances UX via ActiveHelp + custom version template; updates/extends tests accordingly.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
internal/cmd/root.go	Adds context-based shutdown, post-run logger cleanup, custom version template, and ActiveHelp hints.
internal/cmd/flags_core.go	Registers Cobra flag validation groups (mutual exclusion + “one required”).
internal/cmd/root_test.go	Updates/removes old preRun validation assertions and adds new tests related to context/hooks/templates.
test/integration/binary_test.go	Updates integration expectations for Cobra’s new flag validation error message.

Comments suppressed due to low confidence (3)

internal/cmd/root_test.go:527

• TestFlagValidationGroups currently only checks that the flags exist, but it doesn’t verify that the validation groups are actually enforced (or even registered) by Cobra. A more meaningful test would execute a minimal command after calling registerCoreFlags and assert that Cobra returns the expected validation error when neither --config nor --config-stdin is provided (and that --routed/--unified are rejected together).

// TestFlagValidationGroups tests that flag validation groups work correctly
func TestFlagValidationGroups(t *testing.T) {
	// Note: This tests that the flag validation groups are registered correctly.
	// Actual validation is performed by Cobra during command execution.
	t.Run("mutually exclusive flags registered", func(t *testing.T) {

internal/cmd/root_test.go:546

• TestVersionTemplate doesn’t assert anything about the new version template formatting—it only checks rootCmd.Version is non-empty, which was already true before this change. If the goal is to cover SetVersionTemplate, assert on the template value (via Cobra’s accessor) or run the version command/--version and check the output includes the expected MCPG Gateway prefix.

// TestVersionTemplate tests that custom version template is set
func TestVersionTemplate(t *testing.T) {
	t.Run("version template is set", func(t *testing.T) {
		// The version template should be set during init
		// We can verify the version command works by checking it's not empty

internal/cmd/root_test.go:555

• TestPostRunCleanup only checks that PersistentPostRun is non-nil, but doesn’t verify that cleanup actually runs (or that it closes the expected loggers). Either rename this test to reflect what it asserts (hook is registered) or extend it to execute a command and assert the side effects of postRun (e.g., via observable logger state / test hooks).

// TestPostRunCleanup tests that postRun cleanup is called
func TestPostRunCleanup(t *testing.T) {
	t.Run("postRun is registered", func(t *testing.T) {
		// Verify that postRun hook is set
		assert.NotNil(t, rootCmd.PersistentPostRun, "PersistentPostRun should be set")

---

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[Copilot]

TestContextCancellation only verifies standard library context behavior (timeouts/cancel), and does not exercise the new CLI wiring (e.g., that run() derives from cmd.Context() / cancellation triggers shutdown). Consider replacing this with a test that sets a cancelable context on a command and asserts run() reacts to cancellation (or remove this test if it doesn't validate project behavior).

This issue also appears in the following locations of the same file:

• line 523
• line 542
• line 551

[Copilot]

unifiedServer.Close() is called both via defer unifiedServer.Close() and again inside the shutdown goroutine. UnifiedServer.Close() delegates to launcher.Close(), which calls sessionPool.Stop() and will block up to 1s on subsequent calls, so this can introduce an unnecessary delay and makes shutdown behavior harder to reason about. Prefer ensuring shutdown happens exactly once (e.g., remove the goroutine call and rely on the deferred Close, or switch to an idempotent shutdown method such as InitiateShutdown() guarded by sync.Once).

Suggested change

unifiedServer.Close()

[Copilot]

This assertion is ineffective for verifying that both flags are mentioned: "config" is a substring of "config-stdin", so the check will pass as soon as config-stdin appears. If the intent is to ensure both flags are referenced, check for --config and --config-stdin (or use a stricter match that distinguishes config from config-stdin).

Suggested change

	if !bytes.Contains(output, []byte("config")) || !bytes.Contains(output, []byte("config-stdin")) {
	if !bytes.Contains(output, []byte("--config")) || !bytes.Contains(output, []byte("--config-stdin")) {