merging-claude-settingslisted

# Merging Claude settings ## Overview `ollama-usage setup` writes into a file the user owns and shares with every other tool: `~/.claude/settings.json` (or the project's with `--project`). The governing rule is **never clobber what you did not write.** File: `src/ollama_usage/setup.py`. ## The four invariants 1. **Read defensively.** `read_settings` returns `{}` for a missing file, a corrupt file, or valid JSON that is not an object. It never raises — a broken settings file must not break `setup`. 2. **Merge, don't replace.** `merge_status_line` / `merge_update_hook` mutate the dict in place and return `True` only if something changed. Every unrelated key, and every unrelated `SessionStart` hook, survives untouched. 3. **Idempotent.** Running `setup` twice writes once. If the value already equals what we'd write, the merge returns `False` — even with `--force`. 4. **Atomic write.** `write_settings` writes to a `tempfile.mkstemp` in the *same directory* then `shutil.move`s it into place, so a crash never leaves a truncated settings file. It returns `False` on `OSError`; the CLI turns that into exit `1`. ## What `--force` means here `--force` is narrower than "overwrite the file": - `statusLine`: replaces an existing one (any command). - update hook: replaces **only the managed hook** — the entry whose command contains `ollama-usage update-check`. Other `SessionStart` hooks are never touched, never reordered, never removed. If no managed hook