nx_jam_check.nx

nx_jam_check.nx -- JAM-PHYSICS PRE-FLIGHT GATE (operator: the QIDI X-Max 3 "constantly jams"; identify WHERE the hardware is failing to prevent it, "aka too cold or what"). The #1 jam physics: a move DEMANDS volumetric flow (mm^3/s) = extruded filament volume / move time; the hotend can only MELT a temperature-dependent maximum. Demand > capacity -> under-extrusion -> heatbreak back-pressure -> JAM. QIDIStudio/slicers don't gate on this; we do, per G-code line, with the exact cause and fix. Scans G-code text: tracks M104/M109 S<temp> + G1 F/X/Y/E; for each extruding move computes flow in MILLI-mm^3/s (integer fixed-point, 1.75mm filament cross-section = 2.405 mm^2) and compares against a DATA-DRIVEN capacity table (Rule 11: profile data, not magic numbers). Verdicts name the line, the demanded flow, the capacity, and the FIX (temp to set OR that it's beyond the hotend = slow down). Also counts retraction churn (heat-creep advisory). HONEST BOUNDARY: the PLA capacity table is PROVISIONAL (community-class values); the team's A7 calibration print measures OUR X-Max 3's real curve and replaces the table -- the GATE LOGIC + parser + math are exact and KAT-tested here regardless of the table values. LAWS: struct-free, integer-only, no floats; composes with nx_klipper_gcode_validator (syntax) as the physics gate beside it. license_tier: ORIGINAL