Claude Code reads ANTHROPIC_DEFAULT_MODEL as its lowest-priority startup
model (after --model, ANTHROPIC_MODEL and the settings `model` field). It is
a plain model id, so behind a proxy a bare value is clamped to 200k exactly
like the tier keys. Add it to EXTRA_EXTENDED_CONTEXT_MODEL_ENV_KEYS so
--1m/--no-1m and the saved preference toggle it with the rest.
The `--settings` launch overlay only carried the routing keys plus the five
Anthropic tier keys. Claude Code applies the settings `env` block on top of
the process environment, so a bare CLAUDE_CODE_SUBAGENT_MODEL or
ANTHROPIC_DEFAULT_MODEL persisted on disk silently undid the resolved
--1m result (and a saved [1m] undid --no-1m). Overlay the extended-context
extra keys too.
Verified with a stub Claude binary reading the overlay file:
ccs claude --no-1m -> ANTHROPIC_DEFAULT_MODEL=claude-opus-5, CLAUDE_CODE_SUBAGENT_MODEL=claude-sonnet-5
ccs claude --1m -> both keys suffixed with [1m]
Kenneth Wong
7ae7a5eba6