Implement partial failure mode support for vMCP

[yrobla]

Add configurable partial failure mode to control Layer 1 (discovery) health filtering behavior. The mode determines which backend health statuses are included in capability aggregation.

Mode behaviors:

• "fail" (strict, default): Includes Healthy & Unknown; excludes Degraded, Unhealthy, and Unauthenticated backends
• "best_effort" (lenient): Includes Healthy, Degraded & Unknown; excludes only Unhealthy and Unauthenticated backends

[Copilot]

Pull request overview

This PR implements configurable partial failure mode support for vMCP to control Layer 1 (discovery) health filtering behavior. The feature allows operators to choose between strict ("fail") and lenient ("best_effort") filtering of backend health statuses during capability aggregation.

Key changes:

• Added PartialFailureMode configuration field with two modes: "fail" (strict, excludes degraded backends) and "best_effort" (lenient, includes degraded backends)
• Updated health filtering logic to respect the configured mode during discovery phase
• Extended test coverage with unit tests for mode-aware filtering and E2E tests for both modes

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
pkg/vmcp/health/monitor.go	Added IsBackendUsableInMode function to enable mode-aware health status filtering; deprecated IsBackendUsable for backward compatibility
pkg/vmcp/health/monitor_test.go	Added comprehensive unit tests for IsBackendUsableInMode covering both modes and edge cases
pkg/vmcp/discovery/health_filter.go	Updated FilterHealthyBackends to accept mode parameter and apply mode-specific filtering logic with default to "fail" mode
pkg/vmcp/discovery/health_filter_test.go	Added unit tests for mode-aware filtering including fail mode, best_effort mode, default mode, and unknown mode behavior
pkg/vmcp/discovery/middleware.go	Updated middleware to accept and pass through the partial failure mode parameter to discovery operations
pkg/vmcp/discovery/middleware_test.go	Updated all middleware test cases to include the new mode parameter
pkg/vmcp/server/server.go	Added PartialFailureMode field to Server config and struct; integrated mode into middleware initialization
pkg/vmcp/server/adapter/handler_factory.go	Updated Layer 2 runtime health checks to use "best_effort" mode (hardcoded)
cmd/vmcp/app/commands.go	Added extraction of partial failure mode from config with "fail" as default
test/e2e/thv-operator/virtualmcp/virtualmcp_circuit_breaker_test.go	Added E2E test suite for partial failure modes with two vMCP servers configured differently

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[codecov]

Codecov Report

❌ Patch coverage is 90.76923% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 57.11%. Comparing base (598e21d) to head (083b1e1).

Files with missing lines	Patch %	Lines
cmd/vmcp/app/commands.go	0.00%	6 Missing ⚠️

Additional details and impacted files

@@                                       Coverage Diff                                       @@
##           feat/issue-3036-healthcheck-circuitbreaker-remove-unhealthy    #3181      +/-   ##
===============================================================================================
+ Coverage                                                        57.06%   57.11%   +0.04%     
===============================================================================================
  Files                                                              343      343              
  Lines                                                            34434    34471      +37     
===============================================================================================
+ Hits                                                             19650    19688      +38     
+ Misses                                                           13167    13161       -6     
- Partials                                                          1617     1622       +5     

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[Copilot]

Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated 5 comments.

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