model-switch

scripts/switch-model.sh <model> [--dry-run] [--confirm] [--accept-timeout S] — <model> is one of the CLI's aliases (default|opus|sonnet|haiku|fable) or a claude-* id with an optional [1m] tag; anything else is refused before any write (exit 2).

Order, under one lock per brain (<workspace>/state/.model-switch.lock, held across preflight, send, observation and record so overlapping switches linearize): (1) preflight through the shared sender (scripts/tmux-send-line.sh --dry-run --refuse-if-pending) — refuse on a Codex runtime (exit 4) or when the core's input box carries text (exit 5), nothing written; exit 3 when no live pane exists; (2) count the Set model to lines already on screen (scripts/pane-observe.sh --count), so a stale acceptance from an earlier switch cannot pass as this one; (3) /model <model> + Enter through the shared sender; (4) wait for the CLI to accept: a NEW Set model to line is the switch. A warm core (cached conversation) first shows "Yes, switch / No, go back"; with --confirm — pass it on an owner instruction, the flag is the authorization — the helper answers Enter once and waits again; without it the dialog is cancelled (Escape) and the script exits 6 with nothing recorded. No acceptance within --accept-timeout (default 20 s) is exit 8, nothing recorded. (5) Only then record <workspace>/state/model-switch.json {model, previous, previous_source, accepted, confirmed, ts, by, settings_read} — previous from the runtime's settings.json, else the last record (the CLI does not persist every /model pick, so the file can lag the live session), else null. The script never writes settings.json: Claude Code's own /model persists the choice there (measured 2026-09-04: the key changed hours into a session with no repo writer). Measured the same day on a live core: the send alone exited 0 while the CLI sat at the confirm dialog and the model had not changed — which is why the send is treated as initiation and the record follows acceptance.

Defaults come from the runtime descriptor (sutando-config.sh runtime: brain, socket, session); --brain/--socket/--session/--descriptor-file and SUTANDO_TMUX_* are explicit overrides.

Python comes from sutando-config.sh python-bin, never bare python3. The core-side entry scripts/switch-model.sh only execs this script. An owner message like "switch model to opus" is handled by running it; the dashboard's Quota tile shows the model the proxy then sees.