The 17.2.1 cowork request profile appended context-1m-2025-08-07 for any
model with a 1M catalog window, but that gate only runs on the OAuth path.
Subscription (Pro/Max) credentials have no long-context credit balance, so
Anthropic hard-429s ('Usage credits are required for long context requests')
on every beta-gated 1M model regardless of prompt size, breaking all
subagents (task/smol/scout resolve to claude-sonnet-4-6).
The beta is no longer advertised on OAuth requests; subscription accounts
transparently get the standard 200k window. Natively-1M models like
claude-sonnet-5 serve their full window without the beta anyway.
Fixes#7238
