## Explanation

RPC endpoint degraded events (`NetworkController:rpcEndpointDegraded`
and it's chain-level variant) now include `rpcMethodName` in their
payloads. This identifies which JSON-RPC method was being executed when
the endpoint became degraded, enabling better debugging of RPC health
issues.

The method name is captured in `RpcService` via `#currentRpcMethodName`,
set in the `finally` block of the Cockatiel policy's `execute` callback
to minimise the race window between the write and Cockatiel's
synchronous event dispatch.

## References

Fixes: https://consensyssoftware.atlassian.net/browse/WPC-441

* Extension consumer PR: MetaMask/metamask-extension#40176
* Mobile consumer PR: MetaMask/metamask-mobile#26187

<!--
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Are there other links that reviewers should consult to understand these
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Are there client or consumer pull requests to adopt any breaking
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For example:

* Fixes #12345
* Related to #67890
-->

## Checklist

- [ ] I've updated the test suite for new or updated code as appropriate
- [ ] I've updated documentation (JSDoc, Markdown, etc.) for new or
updated code as appropriate
- [ ] I've communicated my changes to consumers by [updating changelogs
for packages I've
changed](https://github.com/MetaMask/core/tree/main/docs/processes/updating-changelogs.md)
- [ ] I've introduced [breaking
changes](https://github.com/MetaMask/core/tree/main/docs/processes/breaking-changes.md)
in this PR and have prepared draft pull requests for clients and
consumer packages to resolve them



<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Medium Risk**
> Introduces a breaking type change and modifies degraded-event emission
data in the RPC service layer; low behavioral risk but could break
downstream implementors and any logic that depends on exact event
payloads.
> 
> **Overview**
> `NetworkController:rpcEndpointDegraded` and
`NetworkController:rpcEndpointChainDegraded` events now include a
`rpcMethodName` field so consumers can identify which JSON-RPC method
was executing when degradation (slow request / retry exhaustion)
occurred.
> 
> This threads the method name from `RpcService.request` through
`RpcService.onDegraded` and into `create-network-client`’s published
messenger events, updates the `RpcServiceRequestable.onDegraded`
listener type (**breaking**), and expands test coverage (including
concurrent-request and “first method triggers degraded” scenarios).
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
c756c02. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

## Explanation

RPC endpoint degraded events (`NetworkController:rpcEndpointDegraded`
and it's chain-level variant) now include `rpcMethodName` in their
payloads. This identifies which JSON-RPC method was being executed when
the endpoint became degraded, enabling better debugging of RPC health
issues.

The method name is captured in `RpcService` via `#currentRpcMethodName`,
set in the `finally` block of the Cockatiel policy's `execute` callback
to minimise the race window between the write and Cockatiel's
synchronous event dispatch.

## References

Fixes: https://consensyssoftware.atlassian.net/browse/WPC-441

* Extension consumer PR: MetaMask/metamask-extension#40176
* Mobile consumer PR: MetaMask/metamask-mobile#26187

<!--
Are there any issues that this pull request is tied to?
Are there other links that reviewers should consult to understand these
changes better?
Are there client or consumer pull requests to adopt any breaking
changes?

For example:

* Fixes #12345
* Related to #67890
-->

## Checklist

- [ ] I've updated the test suite for new or updated code as appropriate
- [ ] I've updated documentation (JSDoc, Markdown, etc.) for new or
updated code as appropriate
- [ ] I've communicated my changes to consumers by [updating changelogs
for packages I've
changed](https://github.com/MetaMask/core/tree/main/docs/processes/updating-changelogs.md)
- [ ] I've introduced [breaking
changes](https://github.com/MetaMask/core/tree/main/docs/processes/breaking-changes.md)
in this PR and have prepared draft pull requests for clients and
consumer packages to resolve them



<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Medium Risk**
> Moderate risk because it changes a public TypeScript listener
signature (breaking) and adjusts degraded-event emission timing to
handle concurrency; runtime behavior should otherwise be unchanged.
> 
> **Overview**
> Adds `rpcMethodName` to degraded telemetry:
`NetworkController:rpcEndpointDegraded` and
`NetworkController:rpcEndpointChainDegraded` payloads now include the
JSON-RPC method that was executing when degradation was detected.
> 
> This is implemented by having `RpcService` track the last-completed
request’s method and attach it to `onDegraded` emissions, with
`create-network-client` forwarding it through to messenger events; types
and tests are updated accordingly, and the
`RpcServiceRequestable.onDegraded` listener signature is **breaking**
due to the new required field.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
4f6e17a. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->