Reject histogram bucket count length changes

[JamesNK]

Description

Malformed histogram telemetry can contain different bucket-count lengths for points in the same instrument and dimension series. The dashboard previously stored both points, then failed while calculating chart data because cumulative histogram values could not be compared across different bucket layouts.

Reject histogram data points when their bucket-count length changes within a series. The valid points already stored for the series remain available, so viewing the instrument no longer fails because of the rejected point.

Add a telemetry repository regression test that sends two individually valid histogram points with different bucket layouts and verifies that only the first point is accepted and stored.

Validation

dotnet test --project tests/Aspire.Dashboard.Tests/Aspire.Dashboard.Tests.csproj --no-launch-profile -- --filter-not-trait "quarantined=true" --filter-not-trait "outerloop=true"

Passed: 1512
Failed: 0
Skipped: 0

Fixes # (issue)

Checklist

• Is this feature complete?
  • Yes. Ready to ship.
  • No. Follow-up changes expected.
• Are you including unit tests for the changes and scenario tests if relevant?
  • Yes
  • No
• Did you add public API?
  • Yes
    • If yes, did you have an API Review for it?
      • Yes
      • No
    • Did you add <remarks /> and <code /> elements on your triple slash comments?
      • Yes
      • No
  • No
• Does the change make any security assumptions or guarantees?
  • Yes
    • If yes, have you done a threat model and had a security review?
      • Yes
      • No
  • No

[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/microsoft/aspire/main/eng/scripts/get-aspire-cli-pr.sh | bash -s -- 18865

Or

• Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/microsoft/aspire/main/eng/scripts/get-aspire-cli-pr.ps1) } 18865"

[Copilot]

Pull request overview

Rejects histogram points whose bucket-count length changes within a dimension series, preventing chart calculation failures while preserving valid telemetry.

Changes:

• Validates bucket-count length before storing histogram points.
• Adds regression coverage for rejecting incompatible points.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
DimensionScope.cs	Rejects incompatible histogram bucket lengths.
MetricsTests.cs	Tests acceptance and rejection counts and retained data.

[github-actions]

Retrying the failed CI jobs for this pull request from the CI run attempt. The rerun is being tracked in the rerun attempt.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

[github-actions]

Tests selector (audit mode)

The full test matrix and all jobs still run in audit mode. The tests and jobs below are what selective CI would run under enforcement.

7 / 100 test projects · 4 jobs, from 2 changed files.

Selected test projects (7 / 100)

Aspire.Cli.EndToEnd.Tests, Aspire.Dashboard.Components.Tests, Aspire.Dashboard.Tests, Aspire.Hosting.DotnetTool.Tests, Aspire.Hosting.RemoteHost.Tests, Aspire.Managed.Tests, Aspire.Playground.Tests

Selected jobs (4)

cli-starter, deployment-e2e, extension-e2e, polyglot

---

How these were chosen — grouped by what changed

🔧 src/Aspire.Dashboard/Otlp/Model/MetricValues/DimensionScope.cs (changed source)
→ 5 via the project graph: Aspire.Dashboard.Components.Tests, Aspire.Hosting.DotnetTool.Tests (2 hops), Aspire.Hosting.RemoteHost.Tests (2 hops), Aspire.Managed.Tests (2 hops), Aspire.Playground.Tests (2 hops)

📦 affected project Aspire.Managed
→ 1 test: Aspire.Cli.EndToEnd.Tests

🧪 tests/Aspire.Dashboard.Tests/TelemetryRepositoryTests/MetricsTests.cs (changed test)
→ 1 directly: Aspire.Dashboard.Tests

Job reasons

Job	Triggered by
cli-starter	• affected project Aspire.Managed • selected test Aspire.Cli.EndToEnd.Tests
deployment-e2e	affected project Aspire.Managed
extension-e2e	• src/Aspire.Dashboard/Otlp/Model/MetricValues/DimensionScope.cs • affected project Aspire.Dashboard
polyglot	affected project Aspire.Managed

---

Selection computed for commit 0b47fe6.

[github-actions]

Retrying the failed CI jobs for this pull request from the CI run attempt. The rerun is being tracked in the rerun attempt.