Integrate circuit breaker with vMCP routing and aggregation

[yrobla]

Complete the circuit breaker integration by wiring it through the Virtual MCP Server stack for automatic backend failure handling.

Configuration wiring (cmd/vmcp/app/commands.go):

• Wire circuit breaker config from YAML to health monitor
• Pass configurable failure threshold and timeout to monitor
• Log circuit breaker enablement on server startup

Capability filtering (pkg/vmcp/aggregator/default_aggregator.go):

• Filter tools, resources, and prompts from unhealthy backends
• Skip capabilities when backend status is Unhealthy, Unknown, or Unauthenticated
• Keep capabilities from Healthy and Degraded backends (degraded backends are still operational)
• Add isBackendHealthy helper for status evaluation

Routing protection (pkg/vmcp/router/default_router.go):

• Check backend health before routing requests
• Return ErrBackendUnavailable when backend is unhealthy
• Add isTargetHealthy helper for status evaluation
• Log warnings when routing fails due to backend unavailability

Testing (pkg/vmcp/router/default_router_test.go):

• Add HealthStatus to all test fixtures
• Add test cases for unhealthy backend routing failures
• Add test cases for unauthenticated backend failures
• Add test cases for degraded backend success (still operational)
• Cover all three routing methods: tools, resources, prompts

Related-to: #3036

[Copilot]

Pull request overview

This pull request completes the circuit breaker integration for the Virtual MCP Server by wiring the circuit breaker configuration through the routing and aggregation layers to enable automatic backend failure handling.

Changes:

• Wire circuit breaker configuration from YAML to health monitor with configurable failure threshold and timeout
• Filter capabilities (tools, resources, prompts) from unhealthy backends in the aggregator
• Add health checks before routing requests, returning errors for unavailable backends
• Add comprehensive test coverage including E2E tests for circuit breaker lifecycle

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
cmd/vmcp/app/commands.go	Wires circuit breaker config from YAML to health monitor and adds startup logging
pkg/vmcp/aggregator/default_aggregator.go	Filters capabilities from unhealthy backends and adds isBackendHealthy helper
pkg/vmcp/router/default_router.go	Checks backend health before routing and adds isTargetHealthy helper
pkg/vmcp/router/default_router_test.go	Adds test cases for unhealthy, unauthenticated, and degraded backend scenarios across all routing methods
pkg/vmcp/server/integration_test.go	Updates test fixtures to include HealthStatus field
test/e2e/thv-operator/virtualmcp/virtualmcp_circuit_breaker_lifecycle_test.go	Adds comprehensive E2E test for complete circuit breaker lifecycle (open → recovery → closed)

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[codecov]

Codecov Report

❌ Patch coverage is 48.27586% with 30 lines in your changes missing coverage. Please review.
✅ Project coverage is 65.40%. Comparing base (3556e04) to head (d5c6c36).

Files with missing lines	Patch %	Lines
pkg/vmcp/aggregator/default_aggregator.go	47.36%	16 Missing and 4 partials ⚠️
cmd/vmcp/app/commands.go	0.00%	8 Missing ⚠️
pkg/vmcp/types.go	75.00%	2 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff               @@
##           issue-3036    #3530      +/-   ##
==============================================
- Coverage       65.43%   65.40%   -0.04%     
==============================================
  Files             404      401       -3     
  Lines           39359    39288      -71     
==============================================
- Hits            25755    25695      -60     
+ Misses          11617    11610       -7     
+ Partials         1987     1983       -4     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[Copilot]

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated 3 comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[github-actions]

Large PR Detected

This PR exceeds 1000 lines of changes and requires justification before it can be reviewed.

How to unblock this PR:

Add a section to your PR description with the following format:

## Large PR Justification

[Explain why this PR must be large, such as:]
- Generated code that cannot be split
- Large refactoring that must be atomic
- Multiple related changes that would break if separated
- Migration or data transformation

Alternative:

Consider splitting this PR into smaller, focused changes (< 1000 lines each) for easier review and reduced risk.

See our Contributing Guidelines for more details.

---

This review will be automatically dismissed once you add the justification section.