feat(core): emit Kubernetes Events on Agent/ModelConfig/MCPServerTool/RemoteMCPServer reconciles

[braghettos]

What

Adds Kubernetes Events on reconcile to the Agent, ModelConfig, MCPServerTool, and RemoteMCPServer controllers, so users can see reconcile outcomes with kubectl describe / kubectl get events. This is the second of the three observability gaps proposed in #2148.

Today these four controllers emit no Events (unlike agentharness-substrate-controller, which already does), so a bad Agent/ModelConfig/MCPServer gives no signal in kubectl describe.

How

Each controller gains an optional Client + Recorder events.EventRecorder and a small nil-guarded recordEvent helper that re-fetches the reconciled object and emits an Event against it, mirroring the existing substrate-controller pattern.

Emitted events:

Controller	Success	Failure
Agent	Normal Accepted	Warning ReconcileFailed
ModelConfig	Normal Accepted	Warning ReconcileFailed
RemoteMCPServer	Normal Accepted	Warning ReconcileFailed
MCPServerTool	Normal ToolsDiscovered	Warning ValidationFailed (spec validation) / Warning ReconcileFailed (transient)

Recorders are wired from pkg/app/app.go via mgr.GetEventRecorder(...).

Additive / no behaviour change

• recordEvent is a no-op when either Recorder or Client is nil, so existing tests and any caller that doesn't wire them are unaffected.
• No new gate/env var — Events are a cheap, additive status surface.
• RBAC is already covered by the leader-election role (events: create,patch), so no RBAC changes are needed.
• No new dependencies (go.mod unchanged); k8s.io/client-go/tools/events and apierrors are already used in-tree.

Testing

• New mcp_server_tool_controller_events_test.go — asserts the correct event type/reason is emitted for each of the three MCPServerTool outcomes (ToolsDiscovered / ValidationFailed / ReconcileFailed) using a fake client + events.NewFakeRecorder, plus a no-Recorder no-panic case.
• go build ./core/..., go test -race -skip 'TestE2E.*' ./core/internal/controller/..., and golangci-lint run all pass.

Notes

Opening as draft / work-in-progress per CONTRIBUTING; happy to adjust event reasons/actions. The remaining gap from #2148 (controller log→OTLP bridge) will follow as a separate PR. Companion PR for gap 1 (token metrics): #2149.

Refs: #2148

[Copilot]

Pull request overview

Adds Kubernetes Event emission to several go/core controllers so reconcile outcomes are visible via kubectl describe / kubectl get events, wiring recorders from the controller manager.

Changes:

• Wire Client + EventRecorder into Agent/ModelConfig/MCPServerTool/RemoteMCPServer controllers from pkg/app/app.go.
• Emit Normal/Warning Kubernetes Events on reconcile success/failure for those controllers via a nil-guarded recordEvent helper.
• Add a unit test covering MCPServerTool event emission paths.

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
go/core/pkg/app/app.go	Wires manager client + event recorders into the four controllers.
go/core/internal/controller/agent_controller.go	Emits Accepted/ReconcileFailed Events for Agent reconciles via recordEvent.
go/core/internal/controller/modelconfig_controller.go	Emits Accepted/ReconcileFailed Events for ModelConfig reconciles via recordEvent.
go/core/internal/controller/mcp_server_tool_controller.go	Emits ToolsDiscovered/ValidationFailed/ReconcileFailed Events for MCPServer tool discovery reconciles.
go/core/internal/controller/remote_mcp_server_controller.go	Emits Accepted/ReconcileFailed Events for RemoteMCPServer reconciles via recordEvent.
go/core/internal/controller/mcp_server_tool_controller_events_test.go	Adds tests validating MCPServerTool emits expected event type/reason.

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