# Erhu V5 Risk Register

Status: L2 V5 build-packet candidate. All risks below block L3/L4 promotion
until evidence is recorded.

| risk_id | area | risk | current_gate | next_evidence |
| --- | --- | --- | --- | --- |
| RISK-001 | acoustic setup | Qianjin-to-bridge target may not produce playable pitch or feel with the selected strings. | Measure installed length and tuner response. | Ruler/caliper photo plus audio or tuner capture. |
| RISK-002 | membrane material | Membrane material may creep, tear, over-damp, or respond inconsistently under bridge load. | Material/acoustic validation required. | Material source, thickness/tension method, humidity notes, and response log. |
| RISK-003 | bridge geometry | Bridge height, mass, foot area, and placement are unmeasured. | Compare at least two variants. | Bridge measurements, photos, and bowed response notes. |
| RISK-004 | body geometry | Resonator dimensions and wall details are not controlled by current CAD/DXF. | Reference or measurement review required. | Measured drawing or reviewed CAD/DXF revision. |
| RISK-005 | visual authority | Existing setup DXF is retained from main but has not been promoted to full V5 shop geometry. | Keep scope limited to setup strip. | V5 drawing review before any L3 claim. |
| RISK-006 | Wolfram/runtime | Computational notes are source-only. | Do not claim runtime validation. | Wolfram run command/date and committed outputs if executed. |
| RISK-007 | cultural/reference review | Erhu-specific setup details may need teacher/player/builder review before public build guidance. | Treat as prototype packet. | Review notes from a qualified reference or measured instrument. |
| RISK-008 | measurement ambiguity | Measuring wrap edge, bridge body, total neck length, or total instrument length could falsely replace the qianjin-to-bridge contact span. | Follow `qianjin-measurement-plan.md`. | Contact-point photos and separate inner/outer measurements. |
| RISK-009 | resonator overclaim | Resonator silhouette or setup-strip marks could be mistaken for body, membrane, or joinery authority. | Enforce `resonator-authority-gates.csv`. | Measured/reviewed resonator drawing before body CAD/DXF promotion. |
| RISK-010 | string-source overclaim | Pitch, tension, or gauge recommendations could be copied from unrelated string-family assumptions. | Enforce `string-source-assumptions.csv`. | Product/source evidence plus installed tuner/audio response. |