continue. FIX ROUND 9, design already decided by the owner's assistant, who CAN read the owner's marked screenshot (you could not). Do NOT ask the owner any more questions: he already answered you (continuous ports, fill the three chamber spaces, shading on all parts and noticeable). Do NOT run vision loops for geometry: use the coordinates below and pixel probes. Keep your reasoning short and in plain sentences. About 30 minutes ago your thinking filled with runs of '= = = =' (up to 31 percent of its characters) because one turn ran 38 minutes and 35 calls and each thought fed the next; if you notice your thoughts turning into symbols or repeats, stop thinking and make the next edit. Work in small steps. After EACH of the 3 parts: run the measuring tool, look at one crop, write 5 lines of progress, then continue. If you reach about 40 tool calls, end the turn with a short status and wait for 'continue'.

WHAT THE OWNER MARKED (his screenshot is an attachment to his message; the owner's assistant mapped the 5 red marks onto engine pixels, an overlay is at head_t6_marks.png, yellow rulers in engine px; do not rely on viewing it, use the numbers):
 Mark 1: from (765,251) curving down to (797,286): the pointed peak of casting just ABOVE the intake port mouth at the head's left face.
 Mark 2: from (1006,280) up to (1050,244): the same pointed peak above the EXHAUST port mouth at the right face.
 Marks 3, 4, 5: at the chamber roof, y 392 to 399: (3) x 818-827, the gas notch left of the intake valve head and its seat wedge; (4) x 880-922, the gas gap between the two valves around the plug; (5) x 972-990, the notch right of the exhaust valve head.

PART 1, PORTS (ROOT CAUSE FOUND, tiny fix). In index.html around lines 449-457 the port centrelines are single quadratic beziers in mm: portIn = [[-66,252],[-46,234],[-22,226]] and portEx = [[22,226],[46,234],[66,252]]. The stroke (48 px wide, butt cap) therefore STARTS exactly at the head's side face (x=768 and x=1032, y=296) heading down-inward at 42 degrees, so the butt cap is a diagonal cut across the face and leaves a pointed triangular tooth of casting above (and below) each mouth. That tooth is what the owner marked. FIX: make each port leave the head perpendicular to its face: set the FIRST control point's y equal to the start point's y so the start tangent is horizontal: portIn = [[-66,252],[-46,252],[-22,226]] and portEx = [[22,226],[46,252],[66,252]]. The cap is then a vertical line exactly on the face, the mouth is a clean 48 px opening and the teeth disappear. The gas dots use the same P, so they follow the new curve; keep the intake/exhaust mirror symmetry. Check both mouths in a 5x crop at t=6 (valves shut): no triangular tooth above or below either mouth; the passage runs smoothly into the valve pocket.

PART 2, CHAMBER (marks 3, 4, 5). Real engines have a flat chamber roof with the valve faces flush in it: the closed valve head must not hang into the chamber and the gas must not wrap around it. Today the closed head spans y 376-392 (its top at the roof y=376), with seat wedges around it, so gas shows beside and under it. DESIGN: raise the whole closed valve-head assembly by 16 px so the closed face is FLUSH with the roof: closed head y 360-376 (rect id valveHeadIntake/Exhaust y = mmY(220 - lift) = 360 + 2*lift; poppet polygons valveShapeIntake/Exhaust and the four seat wedges translated up by 16 px; the stems end at the head, shorten each stem by 16 px at its lower end; the head still moves DOWN by 2*lift px as it opens, and the roller, spring and cam geometry do not change). The roof between and beside the valves is then solid casting at y=376 from x=820 to x=980 (draw the casting down to y=376 everywhere in that span), so no gas notch remains at marks 3, 4 or 5. The plug well is an open 32 px slot around the 20 px plug (x 884-916): narrow the well to 24 px (x 888-912) so the plug is embedded in solid head, and let the plug tip end flush at the roof with a small electrode 6 px long below it (y 376-382, same dark tone with the light outline) so the spark still visibly fires at the tip (spark centre stays near (900,380)). Update everything that referenced the old head position: the leader dots' anchor (the dot sits on the head centre = new head rect centre), measure_engine.mjs checks that use the head rect (adapt only what the geometry change forces, say exactly what you changed), the gas clip, flame start. Then verify at t=6 (shut), t=2.4 (intake open) and t=13.6 (exhaust open) in 5x crops: no gas visible beside a shut valve, a clean gap when open, roof continuous.

PART 3, SHADING. Add noticeable depth and detail with SVG gradients, keeping the flat-colour style, the round-6 hues, the outlines, and NO blue, yellow, orange or red hue on metal. Per family: head casting (vertical light to darker toward the bottom/roof), piston (crown highlight, darker skirt below the rings), bore walls/tubes (inner shadow toward the bore), crank web, crank disc and flywheel (radial turned-metal: lighter centre, darker rim), connecting rod (lengthwise gradient, lighter in the middle), valve stems (horizontal cylindrical gradient: dark edges, light centre), valve heads and seat wedges (diagonal light-to-dark following the cone), cam lobes and rollers (radial highlight), plug (subtle vertical). Extend the outline CSS rule (or add stroke attributes) to the new gradient fills so outlines stay. Use a small set of defs (about 8 gradients), not one per element. The shading must be visibly stronger than today at 1x on a 1920x1080 frame, yet text, leaders, dial and HUD stay untouched.

CHECK: node measure_engine.mjs --times 5.5,7.33,8,11.5,16,21.5,24,27.5,31 --shots workspace/meas9 : all checks must pass (the cam-lobe checks from round 8 included). Do not loosen a check that a real defect would trip.
THEN: BEFORE rendering back up the round-8 renders: final.mp4 -> final_v8.mp4 and review.mp4 -> review_v8.mp4 (do not overwrite older backups). Render review.mp4 and final.mp4; ffprobe gate (h264, 1 video stream, 1920x1080, 30/1, 32.0 s +/-0.05, no audio); append round 9 to REVIEW.md, REPORT.md, NOTES.md. Final report: per part done or not done with evidence, the gate, files written, honest about anything imperfect.