--model flag does not override settings.json model field

Summary

The --model flag at launch does not override the "model" field in ~/.claude/settings.json. The settings value always wins.

Steps to Reproduce

1. Set "model": "opusplan" in ~/.claude/settings.json (resolves to claude-sonnet-4-6)
2. Launch with claude --model nemo-tools pointing at an Ollama backend via ANTHROPIC_BASE_URL
3. Status bar shows "Sonnet 4.6" — the --model flag is ignored

Also tested:

• ANTHROPIC_MODEL=nemo-tools env var before launch — ignored
• --settings '{"model":"nemo-tools"}' inline JSON — ignored (merges additively, base file wins)
• Temporarily swapping settings.json on disk — works, confirming the file is always authoritative

Expected Behavior

Per the docs, priority order should be:

1. /model command during session
2. --model flag at launch
3. ANTHROPIC_MODEL env var
4. settings.json "model" field

None of 1-3 actually override 4 in practice.

Context

Use case: launcher that routes to a local Ollama backend (zero-cost) for lightweight tasks, while keeping settings.json set to opusplan for regular sessions. Currently impossible without swapping the settings file on disk, which is fragile.

A CLAUDE_CODE_SETTINGS_PATH env var pointing to an alternate settings file would solve this cleanly.

Environment

• Claude Code v2.1.91
• macOS Darwin 24.6.0 arm64
• settings.json "model" value: "opusplan"