[External reference] OpenCode Go Kimi K3 upstream failures can resemble Senpi runtime issues

## Summary

This is **not a confirmed Senpi bug**.

This issue exists as a local reference for agents and contributors who may not
have access to external repositories or provider-status context while debugging
Kimi K3 failures.

`opencode-go/kimi-k3` has recently experienced upstream/OpenCode Go failures that
can resemble Senpi stream, retry, recovery, or agent-loop problems.

Please check the upstream condition before treating K3 failures as a Senpi
runtime regression.

## Upstream reference

OpenCode issue:

https://github.com/anomalyco/opencode/issues/43071

Reported symptom:

```text
Upstream request failed: Endpoint is unavailable.
```

The upstream report includes OpenCode Go + Kimi K3 and repeated retry/failure
behavior.

## Locally observed symptoms

Additional symptoms observed with Kimi K3 through OpenCode Go include:

```text
Provider stream start timed out after 30000ms
Provider stream start timed out after 90000ms
Retry failed after 2 attempts
Stream ended without finish_reason
Router.Unavailable
```

A failed stream may also leave the session appearing to remain in a working or
retry state.

Failed requests may consume OpenCode Go usage/quota even when no usable response
is returned.

Other OpenCode Go models have remained usable during at least some of these
incidents.

## Why this matters for Senpi debugging

These symptoms can easily be mistaken for problems in:

- stream watchdogs
- retry/fallback handling
- model recovery
- provider routing
- agent-loop termination

If the affected model is specifically:

```text
opencode-go/kimi-k3
```

first verify whether K3 works directly or whether another OpenCode Go model works
under the same account/environment.

A useful control is to switch temporarily to another Go model such as
`kimi-k2.7-code` or another currently available model.

Only investigate Senpi internals after ruling out the upstream K3 failure mode.

## Scope

This issue does **not** mean all Kimi-related failures are external.

Senpi has had separate Kimi-specific implementation bugs in the past, and future
ones are still possible.

The purpose of this issue is simply to prevent agents from spending time
debugging Senpi for a failure that may originate in OpenCode Go or its upstream
Kimi K3 route.

No repository file, test, or implementation entry point is identified. Read this issue and the linked OpenCode issue first; any follow-up should preserve the Kimi K3 upstream-check guidance and distinguish external failures from confirmed Senpi bugs.

Written by the indexing model from the issue text.