[aw] Expert Code Review (on open) failed

### Workflow Failure

**Workflow:** [Expert Code Review (on open)](https://github.com/dotnet/msbuild/blob/main/.github/workflows/review-on-open.agent.md)
**Branch:** copilot/lower-non-mt-rule-severity
**Run:** https://github.com/dotnet/msbuild/actions/runs/34482421878
**Pull Request:** [#14994](https://github.com/dotnet/msbuild/pull/14994)

> [!WARNING]
> **Engine Failure**: The `copilot` engine terminated unexpectedly.

**Last agent output:**
```
Check your COPILOT_PROVIDER_API_KEY or COPILOT_PROVIDER_BEARER_TOKEN.
Changes +0 -0
Duration 16m 26s
Tokens ↑ 8.6m (8.2m cached) • ↓ 170.5k
Resume copilot --resume=ef4f3c3a-767e-46e1-86ef-c826a81b512b
Authentication failed with provider at http://172.30.0.30:10002 (HTTP 403).
Check your COPILOT_PROVIDER_API_KEY or COPILOT_PROVIDER_BEARER_TOKEN.
Changes +0 -0
Duration 0s
Resume copilot --resume=26a3583f-13e2-4c80-86d4-9412b00dba45
```

### Action Required

**Assign this issue to an agent** to debug and fix the issue.

Debug with any coding agent

Use this prompt with any coding agent (GitHub Copilot, Claude, Gemini, etc.):

````
Debug the agentic workflow failure using https://raw.githubusercontent.com/github/gh-aw/main/debug.md

The failed workflow run is at https://github.com/dotnet/msbuild/actions/runs/34482421878
````

Manually invoke the agent

Debug this workflow failure using your favorite Agent CLI and the `agentic-workflows` prompt.

- Start your agent
- Load the `agentic-workflows` skill from `.github/skills/agentic-workflows/SKILL.md` or
- Type `debug the agentic workflow review-on-open.agent failure in https://github.com/dotnet/msbuild/actions/runs/34482421878`

> [!TIP]
>
> Stop reporting this workflow as a failure
>
> To stop a workflow from creating failure issues, set `report-failure-as-issue: false` in its frontmatter:
> ```yaml
> safe-outputs:
> report-failure-as-issue: false
> ```
>
>

> Generated from [Expert Code Review (on open)](https://github.com/dotnet/msbuild/actions/runs/34482421878) · copilot · 1K AIC · [◷](https://github.com/search?q=repo%3Adotnet%2Fmsbuild+is%3Aissue+%22gh-aw-workflow-id%3A+review-on-open.agent%22&type=issues)

Start with .github/workflows/review-on-open.agent.md and the failed run linked in the issue, then read .github/skills/agentic-workflows/SKILL.md. Reproduce or inspect the HTTP 403 authentication failure from the workflow environment. Done means the review-on-open workflow completes without the copilot provider authentication error.

Written by the indexing model from the issue text.