[BUG] [BUG] Cowork on macOS: repeated 404 on /model_configs/claude-opus-4-7[1m] surfaces as "socket connection closed unexpectedly"

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

What's Wrong?
The Cowork tab in Claude Desktop on macOS repeatedly shows "The socket connection was closed unexpectedly" during sessions. The wording suggests a transport-layer failure, but claude.ai-web.log shows the actual cause is a persistent 404 on the model config endpoint:
GET /api/organizations/{ORG_UUID}/model_configs/claude-opus-4-7[1m]
→ 404 Not Found
The [1m] suffix appears to be a context-length variant tag (1M context). The endpoint does not recognise this identifier and returns 404. React Query retries on a 1–5 minute interval, each 404 surfaces as a connection error toast in the UI, and dependent requests then cascade-fail with TypeError: Failed to fetch, tearing the session down.
The model selector in Cowork only exposes "Opus 4.7" with no user-toggleable option to choose a non-[1m] variant, so the user cannot work around this from the UI.

What Should Happen?

Expected Behaviour
The Cowork session should hold its connection. Either:

the [1m] variant should be served by model_configs, or
the client should not request a variant the backend does not serve, or
a 404 on this config endpoint should not surface as a transport-layer socket error and should not cascade-tear-down dependent requests.

Error Messages/Logs

2026-05-25 17:48:29 [error] [REACT_QUERY_CLIENT] QueryClient error:
  {"type":"not_found_error","statusCode":404,
   "endpoint":"/api/organizations/{ORG_UUID}/model_configs/claude-opus-4-7[1m]",
   "method":"GET","message":"Not found"...}

Repeats at: 17:51:00, 17:55:26, 17:58:47, 18:08:27, 18:12:37, 18:18:37,
            18:19:18, 18:21:51, 18:25:12, 18:26:07, 18:33:18, 18:33:23,
            18:35:15, 18:39:44, 18:39:47

Interleaved with cascading "TypeError: Failed to fetch" from
vendor-query in /claude-ai/v2/assets/v1/.

Steps to Reproduce

Steps to Reproduce

Open Claude Desktop on macOS.
Open the Cowork tab.
Start any session with Opus 4.7 selected (the only option).
Within 1–5 minutes, observe "The socket connection was closed unexpectedly" toast.
Errors recur on a 1–5 minute cadence and progressively tear down the session.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

1.8555.2 (a476c3), built 2026-05-22T23:04:37.000Z

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

Environment Info

Platform: macOS (Apple Silicon, Mac mini)
Claude Desktop version: 1.8555.2 (a476c3), built 2026-05-22T23:04:37.000Z
Mode: Cowork (Local Agent Mode)
Model selected in UI: Opus 4.7

Troubleshooting Already Attempted

Killed Claude.app process; deleted ~/Library/Application Support/Claude/vm_bundles/; relaunched.
No effect: 404 pattern recurs against a freshly downloaded VM bundle.
Verified Anthropic status page reports all components operational at time of incident.
Confirmed regular claude.ai web chat is unaffected on the same machine and network.