Add new ResourceStartedEvent that fires after resource starts but before health checks

[Copilot]

• Add new ResourceStartedEvent class that fires after resource starts but before health checks
• Implement event firing in ResourceHealthCheckService when resource enters Running state
• Add extension method OnResourceStarted for easy event subscription
• Create basic test for ResourceStartedEvent properties
• Move ResourceStartedEvent firing logic inside MonitorResourceHealthAsync method (addresses review feedback)

Changes Made:

• New Event Class: ResourceStartedEvent that implements IDistributedApplicationResourceEvent
• Event Timing: Fires immediately when resource state transitions to "Running", before health check monitoring begins
• Public API: Extension method OnResourceStarted for easy event subscription
• Test Coverage: Basic test to verify event properties are correctly set
• Code Organization: Event firing logic moved into MonitorResourceHealthAsync for better encapsulation

Benefits:

• Provides immediate feedback when resources start successfully
• Fills timing gap between BeforeResourceStartedEvent and ResourceReadyEvent
• Enables faster status updates for dependent resources (like dev tunnels)
• Follows consistent patterns with existing resource events

The ResourceStartedEvent is now fired at the beginning of the MonitorResourceHealthAsync method, consolidating all health monitoring logic in one place.

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[davidfowl]

@copilot move this logic inside of MonitorResourceHealthAsync

[Copilot]

Done! I've moved the ResourceStartedEvent firing logic inside MonitorResourceHealthAsync method. The event is now fired at the very beginning of the health monitoring process, which provides better encapsulation and consolidates all the health monitoring logic in one place. (commit c3e7b8c)

[github-actions]

🚀 Dogfood this PR with:

⚠️ WARNING: Do not do this without first carefully reviewing the code of this PR to satisfy yourself it is safe.

curl -fsSL https://raw.githubusercontent.com/dotnet/aspire/main/eng/scripts/get-aspire-cli-pr.sh | bash -s -- 11381

Or

• Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/dotnet/aspire/main/eng/scripts/get-aspire-cli-pr.ps1) } 11381"

[Copilot]

Pull Request Overview

This PR introduces a new ResourceStartedEvent that fills the timing gap between when a resource starts and when health checks complete. The event fires immediately when a resource transitions to "Running" state, enabling faster status updates for dependent resources.

Key changes:

• Adds ResourceStartedEvent class implementing IDistributedApplicationResourceEvent
• Fires the event in MonitorResourceHealthAsync before health check monitoring begins
• Provides OnResourceStarted extension method for easy event subscription

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/Aspire.Hosting/ApplicationModel/ResourceStartedEvent.cs	New event class that fires when resource starts but before health checks
src/Aspire.Hosting/Health/ResourceHealthCheckService.cs	Implements event firing logic in MonitorResourceHealthAsync method
src/Aspire.Hosting/DistributedApplicationEventingExtensions.cs	Adds OnResourceStarted extension method for event subscription
tests/Aspire.Hosting.Tests/Health/ResourceHealthCheckServiceTests.cs	Basic test to verify ResourceStartedEvent properties