Support back ground lock

[a-baran-orhan]

Summary

• add back as a supported axial ground-lock contact for supine movements
• keep the newer grouped, per-side, and natural-language contact syntax intact
• reject unsupported contact names instead of silently ignoring them
• update the LLM prompt, specification, canonical dead-bug example, and generated docs
• add parser, renderer, and full-pipeline regression coverage

Root cause

The authoring prompt told LLMs to lock whatever touches the floor, so an LLM reasonably generated ground-lock: back for a dead bug. The parser accepted the word, but the renderer had no matching contact mapping, making the directive a silent no-op. Replacing it with feet changed rendering but was anatomically incorrect.

Impact

LLMs and humans can now use the anatomically correct ground-lock: back for dead bugs and other supine floor work. The torso surface remains planted while opposite limbs move, and invalid contact names produce line-anchored validation errors.

Validation

• npm test — 271 tests passed
• npm run typecheck
• npm run build
• rebased onto current origin/main

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Project	Deployment	Actions	Updated (UTC)
posecode	Ready	Preview, Comment	Jul 16, 2026 5:37am