add-servo-profile

name	add-servo-profile
description	Add a new servo spec or mass profile to params.py, then regenerate the model and verify. Use when asked to add/support a new servo (e.g. a new Feetech/Dynamixel model) or a new mass profile to the Stack-chan simulator.

Add a servo or mass profile

All physical parameters live in src/stackchan_sim/params.py (the single source of truth). Add the new entry there, keep facts vs estimates separated and cite the source, then regenerate and verify.

Add a servo

1. In params.py, find the SERVOS dict (values are ServoSpec). Add a key with: name, stall_torque_Nm, no_load_speed_rad_s, mass_kg, note. Convert catalog units explicitly (e.g. kgf·cm via the existing KGFCM_TO_NM, sec/60° → rad/s) and cite the datasheet/source in a comment. Keep facts (datasheet specs) separate from estimates.
2. Do NOT change DEFAULT_SERVO unless asked.

Add a mass profile

1. Find the MASS_PROFILES dict (values describe base/pan/head split + total). Add a key following the existing pattern; document whether numbers are facts (official total) or estimates (per-link split), per the report.

Regenerate & verify (always)

3. Regenerate the committed MJCF snapshot if the default profile/servo geometry could change: run the /regenerate-model skill and review git diff of models/stackchan/stackchan.xml.
4. Run tests: uv run pytest -q (see tests/test_params.py).
5. Audit traceability with the params-auditor subagent (it checks every value traces to the report and that facts/estimates stay separated).
6. The new key automatically appears in the dashboard selectors (served from /api/model); optionally confirm with /verify-dashboard.

Notes

• Servo limits are enforced in the model: stall torque via actuator forcerange, no-load speed via ServoController rate-limiting — so the new specs take effect without extra wiring.
• Keep new physical numbers traceable to a primary source; do not guess.