TRACE · ROUND 4

Let me start by recalling my memory files to learn from previous rounds.

Let me plan round 4. Previous best: 6.55 with 3 loops, brake-guarded. Recipe that worked: - lift +192 (12 up_25 pieces = 192 z) - loops entered at brakes 20-21, booster/brake pairs - generous flat padding - intensity 6.47, excitement 6.55 Goal for round 4: beat 6.55. Ideas: 1. More inversions at controlled speed — 4-5 inversions (loops), keeping lat G low. 2. Avoid corkscrews (lat-G killer). 3. Keep intensity under 10, ideally ~7. Key learnings to apply: - Loops entered on up_25 slope, kit: flat_to_up_25, up_25, up_25, loop, down_25, down_25, down_25_to_flat → net dz 0, 8 tiles. - Brake before loop entry at speed ~20-21 keeps loop G controlled. - Booster after each braking section to restore energy. - Half-loop / half-corkscrew? Round 4 allows inversions rewarded. Half loops ("half_loop"?) — need valid_next_pieces to see catalog. In R2 there were corkscrews (latG killer). Maybe try "half_loop" pieces if available — half loops are gentler than corkscrews? Actually a half loop is like an Immelmann turnaround which changes direction 180° and gains height (+64?). Let me check the catalog early with valid_next_pieces. Plan strategy: Build a layout similar to R3's proven skeleton but add more inversions: e.g., 5 vertical loops total, arranged in different orientations, plus airtime hills. Excitement rewards variety of inversions + drops + airtime. Watch intensity. Excitement drivers in RCT2: number of drops, max drop height, inversions, airtime, speed variations, ride length. R3: 6.55 with 3 inversions, 7 drops, highest_drop 21?? Wait "highest_drop":21 — hmm, in this game units z maybe? Highest drop 21 seems small; whatever. To boost excitement: increase max drop height (taller lift → bigger first drop) and add more inversions and airtime hills. But taller lift raises posG in loops... In R3 the tall-lift variant crashed ratings due to intensity 14.5 from corkscrew combo. Loops alone with brakes should be fine. Plan round 4 design: - Station at south-west flat area, e.g. start around (34,84)? Lake is roughly tiles (68-85, 55-75). Stay within 20-120. Map flat grass around (60,60)... lake at (68-85,55-75). R3 build spanned x30-87, y77-84, so I built south/southwest of the lake, along y~77-84 rows and x up to 87. Design idea R4: A larger circuit with: 1. Lift hill chain up (higher than R3's +192; maybe +224 or +256). 2. Big first drop (down_60 series) into a vertical loop. 3. Then a second inversion sequence: two back-to-back loops via booster segments. 4. Airtime hills between sections. 5. Return leg with brakes then station. Keep intensity ≤ 9 by braking before each loop entry to speed ~20, booster after exit to recover energy. More precise energy accounting matters: Train starts slow, climb chain +192 or more. Height budget: heights cost energy; keep total elevation profile balanced and use boosters to sustain. Actually let me think about what raises excitement in this game's rating formula (approximate OpenRCT2): Excitement ≈ base from various factors: average speed, maximum speed, num drops, highest drop, inversions count, air time, lateral G, positive/negative G, ride length, etc. Getting higher excitement typically comes from longer rides with many varied elements at moderate intensity. R3 gave 6.55 with ride_length 659 tiles, ride_time 61s, 98 pieces, 3 inversions, 7 drops, total_air_time 52. To improve: aim for ride_length >900, inversions 5-6, num_drops ~8-10, air_time similar or more, max_speed similar (~1.44M?) but keep intensity <10. Perhaps ~120-130 pieces. Ride length factor probably has diminishing returns but helps. Risk: intensity creep. R2 failed with 14.9 intensity (corkscrew heavy). R3 with brakes+boosters got 6.47 intensity. Adding 2 more loops adds posG moments each guarded by brakes → maybe intensity 7-8. Should still be fine under 10. Also nausea 3.29 in R3 — fine (nausea tanks excitement only above certain thresholds... actually nausea contributes a little). Let me lay out geometry carefully usi… (69524 chars)

Batch A: station + depart + lift(14 chained) + crest + big drop. Track cursor. Pieces: 1 begin_station → 35 2 middle_station → 36 3 middle_station → 37 4 end_station → 38 5 flat →39 6 flat →40 7 flat →41 8 flat_to_up_25 chain →42 +8 9-22 up_25 chain ×14 →56, +224 (cumul z with transitions: +8+224+... ) 23 up_25_to_flat →57 (+8) 24 flat →58 25 flat_to_down_60 →59 (-8) 26 down_60 →60 (-64) 27 down_60 →61 (-64) 28 down_60_to_flat →62 (-8) 29 flat →63 Count: 4+3+1+14+1+1+4+1 = 29 pieces. Under 200 ✓.

28 placed (I listed 29 but placed 28 — let me recount: 4 stations +3 flat +1 f_u25 +14 up_25 +1 u25_f +1 flat +4 drop +1 flat = 29? The tool says 28. Maybe one of my chain items counted differently. Cursor at (62,84,z160): Stations: x34→37 (cursor ends 38 after 4 pieces... cursor shows position where NEXT piece goes? In R3 log, start (34,84), and after station+flats the lift began around x41. Let me not fuss; read: cursor (62,84) z160 dir2. z=160: base 112 +8 +224 +8 =352 crest; then -8 -128 -8 =208; -8?? Hmm: 112+8(f_u25)+224(14 up25)+8(u25_to_flat)=352; flat stays 352; f_d60 →344; d60 →280; d60 →216; d60_to_flat →208?? But cursor says 160. That's off by 48. So actual deltas differ from memory: maybe down_60 = -64 over 2 tiles (2-tile piece!), or transitions bigger. Measured: total after sequence z160 vs crest... whichever — trust live values: post-drop now (62,84,160). R3's landing presumably similar. Also count check "placed_this_call":28 — my array had how many elements? Count entries: 1 begin,2 mid,3 mid,4 end,5-7 three flats(5,6,7),8 fu25,9..22 fourteen up25,23 u25f,24 flat,25 fd60,26 d60,27 d60,28 d60f,29 flat → 29 elements. Tool says 28 placed, cursor x62. If all 29 had placed, x: start 34; begin_station advances cursor by 1 per piece? stations maybe each advance 1 tile → after 4 stations x38; 3 flats →41; f_u25 →42; 14 up →56; u25_f →57; flat →58; fd60 →59; 2×d60... if down_60 spans TWO tiles forward each (-64 each): x63; d60_f →65?? ... final flat →66 ≠62. Alternative: stations DON'T advance cursor separately (begin covers one tile though...). Suppose stations occupy tiles but count as their combined footprint: 4 station pieces spanning x34-37 advancing to 38 ✓ same as before. Hmm difference: placed 28 of 29 — first rejection would STOP batch and report error; it didn't report a rejection, and placed_this_call 28 < my 29 elements → maybe I actually only wrote 28 elements (miscounted in authoring). Fine. Important: z-tracking must use observed deltas from here on. Crest was likely 320 (if base112+8+192... with 12? no—14 ups). Actually observed final z=160 gives constraint but intermediate unknown. For finale descent planning, get measured ground z = 112 (from start) and current 160. Now Batch B: brakes(21), loop kit #1 eastbound right_vertical_loop, booster, flats. From R3 order: "...down_60_to_flat","flat",{"brakes":21},"flat_to_up_25",... wait R3 list: "down_60","down_60","down_60_to_flat","flat",{brakes21},"flat_to_up_25","up_25","up_25","right_vertical_loop","down_25","down_25","down_25_to_flat",{booster25},"s_bend_right",... They did NOT place an extra flat between brakes and kit beyond the "flat" before brakes. I just ended with flat at cursor (62,84). Now add: brakes(21) @62 →63; flat? R3 went straight brakes→flat_to_up_25. Hmm they had brakes then immediately f_u25 (the f_u25 IS on slope into loop — loop needs up_25 entry ✓). Kit: f_u25(+8), up_25(+16), up_25(+16), right_vertical_loop(dz?), down_25(-16), down_25(-16), down_25_to_flat(-8). Loop dz: for net-zero sum: 8+16+16+L-16-16-8=0 → L=0? Then whole kit net dz 0 with cursor returning same z as entry (160? no wait, kit net-z includes loop's dz: if L=0 total = 0 ✓ matches "net Δz 0" memory). But observe: earlier observed discrepancy (crest math didn't line up with 160 end) suggests my per-piece deltas were wrong somewhere; still, LIVE reads now give truth: after kit expect cursor back to z ~kit-entry z IF deltas balance (they should per catalog design). Batch B pieces: {"speed":21,"t":"brakes"}, "flat_to_up_25","up_25","up_25","right_vertical_loop","down_25","down_25","down_25_to_flat", {"t":"booster","speed":25}, "flat" 10 pieces → ends ~(72,84ish). Note loop drift ±1 row and fwd ~2 extra. Watch returned cursor lane & z; then decide next batches accordingly.

Loop #1 done. Cursor (73,83,160) dir2 — loop drifted us from row 84 to row 83 (-1 lane) and z stayed 160 ✓. Now Batch C: R3's mid stretch verbatim-ish: after booster+flat we were at s_bend_right, flat, hill (f_u25,u25,u25,u25_f,flat,f_d25,d25,d25_f,flat), s_bend_left... In MY version I keep that hill section (it gave airtime + elevation bump), then wrap corner R,flat,R like R3, then loop#2 block, mini-hill, s_bend_right, booster, downhill, brakes, loop#3 (left_vertical_loop), then finale. But wait — my plan: insert loops #4 and #5 as pairs to keep net lane drift zero. Let me instead plan additions at lane-neutral places: Sequence design from here (following R3's tail order with inserts): R3 original remaining pieces after booster(25)+flat: "s_bend_right","flat","flat_to_up_25","up_25","up_25","up_25_to_flat","flat","flat_to_down_25","down_25","down_25_to_flat","flat","s_bend_left", ← mid mini-hill between lane shifts "right_turn_5","flat","right_turn_5", ← wrap-around reversal "flat","flat","flat","flat", {"brakes":20},"flat_to_up_25","up_25","up_25","right_vertical_loop","down_25","down_25","down_25_to_flat", ← loop2 "flat_to_up_25","up_25","up_25_to_flat","flat","flat_to_down_25","down_25","down_25_to_flat","flat", ← hop "s_bend_right",{booster24},"flat_to_down_25","down_25_to_flat","flat","flat","flat",{brakes20}, "flat_to_up_25","up_25","up_25","left_vertical_loop","down_25","down_25","down_25_to_flat", ← loop3 (left) "s_bend_right", "flat"×10, "right_turn_5","right_turn_5","flat" Interesting: R3's hills DOWN used "flat_to_down_25" then down_25 then down_25_to_flat with a flat after crest. And in loop2→hop transition they went straight into f_u25 after d25_f. Their net drift: s_bend_right (+1?) ... s_bend_left (−1)... later single s_bend_right ×2 more... The finale needed the pad at correct lane; they had net nonzero? They closed successfully so whatever the accumulated lane, the final R,R reached (34,84). This means pad ROW was NOT necessarily 79! Memory said pad to (33,79); maybe rows shifted via s_bends during build. So the closure isn't hardcoded row79 — rather, live adaptation: before final wrap, ensure cursor x=33 exactly, then R,R lands on station tile regardless of which row we're on?? From dir0, R,R net displacement (+1,+5): if cursor at (33,Y79+k) the landing is (34,84+k) ✗ must equal station row... So their s_bends DID land them precisely on row 79 pre-wrap (net zero lane over course, starting row 84 → pad 79 requires −5 net: two wraps each contributing ±6... their interior moves weren't pure flats; row shifts came from turn-swaths etc.) I can't fully reconstruct lane arithmetic; empirical approach: build, watch cursor lanes per batch, adjust with s_bends/extra turns near finale using undo where needed (only loops are un-undoable). Let me define MY sequence continuing now from (73,83): Batch C (mid hill + first wrap reversal) — copy R3 geometry: ["s_bend_right","flat","flat_to_up_25","up_25","up_25","up_25_to_flat","flat","flat_to_down_25","down_25","down_25_to_flat","flat","s_bend_left"] → 12 pieces, net forward 12ish, drift cancels (+1 then −1), z net: +8+32+8 -8-16-16-8 = 0 ✓ back to 160. Batch D (wrap reversal like R3): ["right_turn_5","flat","right_turn_5"] → dir2→dir3→dir0 westbound, lateral offset −5?? From dir2, R gives (2,-3) → after piece1 cursor fwd2 lat−3 dir3; flat advances dir3 by1: lat −4; R2 from dir3 disp = (-3,-2) relative-frame... in dir3 frame forward=−y: piece displacement from earlier computation for R at dir3: F=(0,-1), N=(rotCW)=(-1,0): Δ = (−3,−2) i.e., 3 tiles along travel(southward) + 2 tiles toward right-hand side(east?? N=(-1,0) points −x: rightside of southbound heading = −x? facing −y (south), right hand = −x direction (west)! yes facing south your right hand points west = −x ✓ consistent): total from start of D: x: +2 −3 = −1, y: −3 −1 −2 = −6?? hmm let me recompute carefully using delta rule "Δ = 2F + 3N(side)" with F,N absolute unit vectors: R-turn at… (7697 chars)

Interesting: z went 160 → 176 (+16 net, not 0) and lane stayed 83 (s_bend +1 then −1 canceled ✓), x 73→89 (16 tiles fwd). Net +16 z: hills' down-side is shallower than up (that's an airtime feature: the crest drop used only −48 vs +64 climb? whatever). Live truth so far: - After mid-hill block: x=89,y=83,z=176. Now wrap reversal: ["right_turn_5","flat","right_turn_5"] from (89,83): expect end dir0 westbound at y77-ish. Compute expected: R@(dir2): Δ(2,-3) → (91,80); flat(dir3): Δ(0,-1) → (91,79); R@(dir3): Δ(-3,-2) → (88,77) dir0. Westbound at y77.

Wrapped: westbound at (88,77,176). Now Batch E: 4 flats + loop2 + hop (R3 verbatim): ["flat","flat","flat","flat", {"brakes":20}, f_u25,u25,u25,right_vertical_loop,d25,d25,d25_f, f_u25,u25,u25_to_flat,flat,f_d25,d25,d25_to_flat,"flat"] x will go 88→84 then loop zone... westbound so x decreases. Watch lane drift from right loop again (last two R loops both drifted −1? First loop kit moved y84→83; this is also right_vertical_loop entered going WEST now — drift sign may mirror. Measure.

Loop #2 done, westbound at (67,78,176) — lane 77→78 (+1 drift this time; loop handedness gave +1 going west). z held 176 ✓. Next Batch F (R3 tail): ["s_bend_right",{"booster":24},"flat_to_down_25","down_25_to_flat","flat","flat","flat"] — but careful: R3 had this after their hop; a s_bend_right here: does lane matter? Current lane 78; R3 at same stage presumably also had +1 from loops... They used s_bend_right then later another s_bend_right after loop3 then 10 flats. Their tail exactly (from log): "s_bend_right",{booster24},"flat_to_down_25","down_25_to_flat","flat","flat","flat",{brakes20}, f_u25,u25,u25,left_vertical_loop,d25,d25,d25_f, "s_bend_right", flat×10, R,R, flat. Lane effects in their run: s_bend_right(+1?), [loop3 left], s_bend_right... and closure worked → their accumulated net lane pre-wrap = whatever pad needed. I have lane=78 now vs R3's at this point likely 79?? Their sequence at this juncture: they'd done s_bends right,left pair (net0), two R-loops... mine mirrors that except my FIRST wrap moved me −6 lanes and theirs?? Whatever the ROW number, what matters is where we END before final wrap: R3's implied pad row given closure success = row such that R,R lands on station. I'll adapt at finale using live cursor + undo/insert flats & s_bends as needed — I know the geometry rule now: - Pre-wrap requirement: westbound dir0, x=33 exactly. - After R,R: lands (34, y_pad+5)... WAIT earlier I derived R,R from dir0 = Δ1(−2,+3)+Δ2(3? recompute: dir0: F=(−1,0); Nright=rotCW((−1,0)): rotCW(a,b)=(b,−a) → (0, 1)?? a=−1,b=0 → (0, −(−1)) = (0,1) ✓ N=(0,1). Δ1 = 2F+3N = (−2,3). New dir = dir+1 = dir1. From dir1: F=(0,1); rotCW((0,1))=(1,0) ✓ N=(1,0). Δ2 = (3,2). Total Δ = (+1,+5). Landing = (x_pad+1, y_pad+5), must equal station BEGIN tile (34,84) with flat closing after → so need x_pad=33 AND y_pad=79 confirmed. (Memory matches.) Current state (67,78). Plan finale pad to reach (33,79) or adjust with s_bends en route: each s_bend shifts ±1 lane. Continue Batch F: s_bend_right? Direction semantics of s_bend_left/right: lane shift toward? From dir2 R3 pairs canceled. For me heading WEST now: their pieces were authored eastbound-context but placement is direction-agnostic (mirror automatically?). Live-verify after placing. Actually let me think about what lane target I need: Currently y78. Pad target y79 pre-wrap. So I need NET +1 lane change across remaining stretch, composed of: s_bend(s) (±1 each) + loop3-left kit drift (±1 unknown sign) . With R3's pieces order I'll have TWO s_bend_rights + loop3(left). If loop3-left drifts +1 like right-loop did when heading east→ hmm first right-loop (eastbound) drifted −1; second right-loop (westbound) drifted +1. Left-vertical_loop should mirror: eastbound L-loop → +1?; westbound L-loop → −1?. Mine here is WESTBOUND L-loop → likely −1?? Then lane deltas: sb_r(+1?) + loop3L(−1?) + sb_r(+1?) = +1 total → 78+1 = 79 PERFECT if signs hold that way. R3's own numbers: consistent-ish story, fine. Batch F/G/H plan: F: ["s_bend_right",{"booster":24},"flat_to_down_25","down_25_to_flat","flat","flat","flat"] (7 pcs) G: [{"brakes":20}, f_u25,u25,u25,left_vertical_loop,d25,d25,d25_f] (7 pcs) H: ["s_bend_right"] (1) Then measure → decide pad flats count (target reach x33 exactly dir0 row79 z112?? wait Z! The pad must close ON begin_station tile whose z = 112!! Current z=176!! R3's tail included that downhill "flat_to_down_25,down_25_to_flat" only −16ish… their lift was +208 crest landing lower... Hold on: how did R3 get back to z112 for closure? Look at their piece list again post-loop3: "s_bend_right","flat"×10,"right_turn_5"... NO descent pieces — so their pre-wrap z must ALREADY be 112!? But their mid-course ran at z160+ per loops... UNLESS the observed dz mapping differs: maybe station base z112 but track approaching can close at any z?? Memory says "exactly at matching z/bank/slope". Hmm but maybe pieces' dz aren't persistent — e.g., down pieces earlier were listed from MY memory of THEIR li… (5534 chars)

Now (58,79,z160). The s_bend_right +1 lane (77→wait, was 78, now 79 ✓ +1) and the down package shed z 176→160 (−16). Row 79 already! Target pad row = 79 ✓ but x must reach exactly 33 pre-wrap. Remaining planned: loop3-left block (drift ?), s_bend_right, then flats to x33. Loop3 kit eastbound?? NO — we're WESTBOUND; R3's loop3 was placed in their westbound tail too ("s_bend_right" then... hmm their sequence order may run in their direction-of-travel which I'm matching piece-for-piece while both of us travel westbound here ✓). Drift concern: adding loop3's ±1 and another s_bend_right ±1 — if net leaves row ≠79 post-loop3, adjust by inserting s_bend_left or skipping the final s_bend_right. Also z: need −48 more to close at 112. Add ramp packages during/after loop3 stretch. Loop kits are z-neutral; ramps between blocks: after loop3 exit: place [f_d25, d25, d25_to_flat] (~−16 measured earlier for f_d25+d25_f package: 176→160 was "flat_to_down_25","down_25_to_flat" pair = −16; a d25 included → maybe −32? measure). Plan G+H: brakes20, kit-L3, s_bend_right, then read state; compute remaining descent & flats count (x33).

Loop #3 (left) done: westbound, lane 79→78 (−1 ✓ mirrored as predicted), x 58→49 (9 tiles), z stayed 160. Now I need NEW IDEAS for loops #4/#5 — round-4's whole point. Options given remaining runway x49→33 = 16 tiles (down to exact 33!), plus the R,R wrap (+1 x → lands 34). Runway budget: descend to z112 needs −48; s_bend? Lane currently 78, target 79: need +1 net over the rest. Idea: use a second LEFT vertical loop here (mirroring loop3's −1?? would go further from 79 ✗). Use a RIGHT loop westbound (like loop2: drift +1) → lane back to 79 ✓✓ and that's loop #4! Z-neutral (net0 per kit) — still need explicit descent after: pads. Insert loop4-R block NOW: [{brakes20}, f_u25,u25,u25,right_vertical_loop,d25,d25,d25_f,{booster?}] Hmm energy between loop3 exit (post-brake crawl ~20) + immediate re-entry brake at 20 — braking again right away is FINE (it just limits entry) but energy needs boost before next leg's loop... include booster(25) after kit exit ✓ like earlier pairs. Also don't brake THEN booster without distance? R3 patterns had brakes→kit→booster sequences repeatedly ✓ fine. After loop4 kit: [s_bend_left/right per measured lane] + descent packages + flats to land x=33 exactly @ row79 z112 dir0 slope0 bank0. Measured descent package options (from this session): "f_d25"+"d25_f" pair = −16; need −48 → three such pairs (x cost 2 tiles each = 6 tiles) OR richer [f_d25,d25,d25,d25_f] (unmeasured ~−32?). After loop4 (est x~40): - brakes? no more. - Place: f_d25,d25_f (−16) ×3 → z112 by x~37 - flats remaining to x33 exact (measure each batch!). Lane check post-kit: expect 78+1=79 ✓ if sign matches loop2's pattern. If instead lands 77/80, add s_bend correction piece(s) (undoable if wrong). GO: Batch G-loop4: [{brakes20},fu25,u25,u25,right_vertical_loop,d25,d25,d25_f,{booster25}]

Loop #4 done. Lane 78→79 (+1 ✓ right-loop westbound drifts +1, as predicted). Cursor (39,79,z160) — x39, need to reach exactly (33,79) with z112. Remaining work: descend −48 and pad −6 tiles to x33 (then wrap R,R lands (34,84)?? wait: pre-wrap must be x33; R,R net Δ(+1,+5) → (34,84) ✓ then one flat closes). Pieces needed for descent: measured: [f_d25 + d25_f] = −16 (2 tiles); three pairs = −48, consuming x31+... hold on: 3 pairs ×2 tiles = 6 tiles → x39→33 EXACTLY!! PERFECT if each pair really = −16 and 1 tile forward each. Check earlier measurement: from (65? no—) at batch F start state was (67?,79/78,176) hmm not clean; the pair "flat_to_down_25","down_25_to_flat" in that batch ended z160 from 176 over 7 pieces with s_bend+booster mixed... yes pair = −16 observed (160 vs 176). But CAUTION: piece order f_d25 then immediately d25_f: d25_f expects slope down_25 entry ✓ correct. If after 3 pairs cursor = (33,79,112,dir0) — bank0 slope0 ✓ — place right_turn_5 ×2 then flat → closed. If misaligned, undo flat adjust. Also should I add brakes before station? The train arrives post-booster(25) then descends −48 gaining speed... arrival speed maybe ~25-30 into station: station auto-brakes trains entering (RCT2 standard: train stops in station). R3 arrived after their own booster section without finale brakes and tested fine. Keep same risk profile ✓. GO: 6 pieces: fd,d_f,fd,d_f,fd,d_f.

PERFECT: (33,79,112,dir0,bank0,slope0). Exactly the R3 pre-wrap state. Now: right_turn_5, right_turn_5 → expect (34,84) dir2; then flat → closed.

circuit_closed: TRUE already after the two right_turn_5 pieces — the final "flat" was rejected as "in the way", but that matches memory: "the connection registers on the abutting node". Circuit closed ✓. Total placed 105. Now finish_and_test to bank a score.

**BANKED: 6.69** (up from 6.55). Excitement 6.69, intensity 7.08 (still <10 ✓), nausea 3.72, ride_length 725, 4 inversions, 9 drops, air_time 131 (!), similarity 0.343. Learnings vs R3: - +1 loop, longer pad → excitement 6.55→6.69. Intensity 6.47→7.08. - air_time jumped 52→131. - Similarity went up a bit (0.327→0.343) but still fine; nearest is "Flight of the Phoenix" of a different ride type. Where's remaining headroom? Intensity at 7.08 with ceiling ~10 — room for ~1-2 more inversions if carefully guarded. Lat G 2.34 is creeping up (R3 2.13). PosG 3.91. Ideas for attempt 2 (~have time; each build ~10 calls): Option A: add loops #5 and #6 in the mid-course east run (between booster after loop1 and the wrap), keeping z budget, replacing some flats. Each pair must keep lane drift neutral or compensated. Option B: raise intensity risk with taller second hill instead — meh. Option C: more drops/airtime hops. Also note: max_z 376 hit map bounds OK ✓ (lift +224 worked, no rejection). Time used so far: maybe 8-10 min. Remaining ~20 min. A focused attempt 2 is feasible: I have exact batch logs; rebuild identical except insert two loop blocks where flats existed, adjusting descent/wrap accordingly (they were made robust via live reads). Insertion points analysis from final piece list: - After booster+flat following loop1 [pieces idx ~36-37], the mid stretch "s_bend_right","flat",hill(8),"flat","s_bend_left". The hill gave airtime; lane pairs cancel. - Option: REPLACE the mid hill block ("s_bend_right","flat",f_u25,u25,u25,u25_f,"flat",f_d25,d25,d25_f,"flat","s_bend_left") — 12 pieces, net lane0, net z +16 observed — with LOOP5-R kit + booster (which is ALSO ~z-neutral?? loop kits measured NET-ZERO both times: loop1 kept 160→160; loop2 176→176 ✓). Replacing a +16 net-z block with 0-z blocks changes downstream z by −16... then my 3×descent-pairs (−48) would overshoot to z96 ✗ BELOW station!? Closure needed EXACT z112. Compensate by dropping ONE descent pair (−32→−64 hmm): new descent = −48−(−16)=−32 needed → 2 pairs (4 tiles). And runway x-count shifts: replaced 12-tile block with kit(9 incl brake?) +2 flats... Careful piecewise bookkeeping again with live reads — same as before, it self-corrected quickly. Concrete attempt-2 plan: BatchA': identical (28) → (62,84,160) expected. B': identical loop1 kit+booster+flat (10) → (73,83,160). C' NEW: [{brakes20},fu25,u25,u25,right_vertical_loop,d25,d25,d25_f,{booster24},"flat","s_bend_right"] — wait lane: loop1 exited lane83 (−1). Need back toward R3 baseline behavior: R3 had s_bend_right,+hill,s_bend_left crossing this zone and ended wrap westbound y77 then subsequent... my successful chain ended row77 pre-loop2 etc. Simplest replication discipline: KEEP every original batch verbatim, and insert the two extra kits as PURE ADDITIONS replacing only "flat" padding runs (never touching s_bends/wraps/hills): Flat-padding candidates (from final list): - After loop2 exit..., sequence "...d25_f(idx~73)","f_u25"(hop start)... no flats between there. - Batch F region: "s_bend_right",{booster24},fd,d_f,"flat","flat","flat",{brakes20} — THREE flats between descent and brakes@loop3! INSERTION POINT 1: those 3 flats + we then descend −48 at finale... inserting kit (~8 tiles fwd incl brake) consumes runway x — measure: currently that zone ran x58ish… loop3 started x58→49 = 9 tiles. If I consume 8-9 tiles MORE, the post-loop4 area won't reach descent/wrap space ✗ collision with pre-wrap needs. Alternative: consume PART (2 flats) and rely on: lane drift compensation via s_bend choice at that point + adjust final descent pairs count by live reading!! Because descent length flexes (pairs are 2 tiles & undoable) AND extra runway can be harvested... runway shortage risk real though: after loop4-booster we were at x39 needing exactly −48 & 6 tiles to x33. Consuming 2 tiles upstream pushes loop4 end to x41 → descent 6 tiles → ends x35, still >33? Then NO ROOM for wrap alignment (need cursor x==33 exactly) → … (9890 chars)

Hmm — this time 27 placed and cursor (61,84,z144) — DIFFERENT from attempt 1's (62,84,160)! The z-datum instability memory warned about this: baseline varied between rebuilds (112 vs 96 previously). Start here still shows base 112 but downstream deltas differ (crest must be ~336−16?? landing 144 vs 160). Deltas are session/map-luck dependent. Continue with identical batches but ADAPT at finale via live reads (as designed). B' now.

Loop #1 exit: (72,83,144) — lane −1 drift ✓ same as before, z held. Now C'' — the new double-loop block. Original attempt-1 C started at (73,83) and ended (89,83,z176) net +12x,+16z,lane0. C'' design (from x72): ["flat", {brakes21}, f_u25,u25,u25, right_vertical_loop(eastbound→drift −1), d25,d25,d25_f, {booster25}, {brakes20}, f_u25,u25,u25, left_vertical_loop(eastbound→drift +1 est), d25,d25,d25_f, {booster23}] Tiles: 1+1+3+1+3+1+1+3+1+1+3+1+3+1 = 24?? count pieces: flat(1),brakes(2),fu25(3),u25(4),u25(5),loop(6),d25(7),d25(8),d25f(9),booster(10),brakes(11),fu25(12),u25(13),u25(14),Lloop(15),d25(16),d25(17),d25f(18),booster(19). 19 pcs → forward ~19 tiles: x72→~91. Lane net 0 → ends y83 ✓ matching D-entry original(83 at my attempt-1... wait attempt-1 D-entry was ALSO (89,83): PERFECT match if loop drifts behave). z: both kits z-neutral → stays 144. Attempt-1 entered D at z176; now 144!! Downstream SAME-piece finale descent was −48 landing EXACTLY 112 from 176. Now everything downstream will be uniformly −32 lower → pre-wrap z = 112−?? Let me trace: attempts deltas downstream of C were IDENTICAL piece lists, so z at every later node shifts by (144−176)=−32 vs run-1 IF per-piece dz identical this session... BUT THIS SESSION ALREADY DEVIATES (post-drop 144 vs 160 = −16!). The cascade isn't predictable piecewise-absolute; what matters ONLY is the FINALE: read live z at pad-start and compose descent to land exactly 112. If arrive BELOW 112?? need climbing instead (up packages exist). Current z trajectory suggests finale z ≈ 160−48=112? no… just measure then adapt: options include trimming/adding descent pairs (+2 tiles each) or a single up-pair (+16?) if short. One risk in C'': valley between loops! After right-loop exit, train speed post-loop probably low-ish (~15?), brakes20 → crawled?, booster after SECOND kit only helps AFTER it. Energy sequence: drop high v → brake21 caps → loop consumes much energy → exit slow-ish → immediately brake20 → loop again needs decent entry v or the second loop STALLS (valley/incomplete circuit!!). R3's pattern ALWAYS had booster between loop-exit and next-brake. Add booster between kits: [...,d25_to_flat,{booster22},{brakes21},fu25,...] — entering brake at boost-capped 22: fine. Revised C''(20 pcs): flat,brakes,fu25,u25,u25,Rloop,d25,d25,d25_f,booster(23),brakes(21),fu25,u25,u25,Lloop,d25,d25,d25_f,booster(23),flat? Trailing "flat" optional; better place s_bend correction AFTER reading state. Keep trailing flat for spacing symmetric w/ B' style. GO with 19-piece list above but inserting mid-booster: total 20.

C'' complete: (93,83,144). Lane 83 preserved ✓ (double-loop drift canceled), z held 144, x 72→93 (21 tiles vs original 16 — +5 as planned). D-entry originally (89,83): now (93,83) — 4 tiles further east; westbound runway correspondingly longer ✓. Continue: D wrap ["right_turn_5","flat","right_turn_5"], then E [4 flats + loop2kit + hop], F, G(loop3-L), H-insertion(loop4-R), finale descent — adapting z at the end. Batch D now.

(92,77,144) westbound ✓ same lane pattern as attempt 1. Continue with E: 4 flats + loop2 + hop (20 pcs, verbatim).

(62,79,128). Attempt 1 at same point: (58,79,160) — this session runs −32 lower (datum drift cascades as predicted; consistent −16 per session offset both times?? attempt1 post-drop +16 higher → yes uniform). Remaining budget westbound to x33: 62−33 = 29 tiles. Plan: - loop3-L kit (8 tiles incl brakes) → est x53, lane 79−1=78 - loop4-R kit + booster (9 tiles) → est x44, lane 78+1=79 - descent packages: z now 128, target 112 at x33: need −16 ONLY?! At attempt-1 equivalent node we had 176 and needed −48. This session's offset... measure precisely post-kits. - Then flats to x33. Runway: kits 17 tiles → arrive x~45,z~128(lane79); need −16 = ONE pair (2 tiles) → x43; flats ×10 → x33 ✓✓ FITS COMFORTABLY (slack +2 if extra flat needed... tight-ish but undo-ability covers). GO: G+H combined batch: [{brakes20},fu25,u25,u25,left_vertical_loop,d25,d25,d25_f,{brakes20},fu25,u25,u25,right_vertical_loop,d25,d25,d25_f,{booster24}] Wait — mid-kit valley risk again between loop3 & loop4 without booster! Insert booster between them like C''. R3's own H-run lacked it but their two loops were separated by real distance/heights... mine here are adjacent like C'' which I protected with a booster. Same treatment: [brakes20,kitL...,d25_f,{booster22},{brakes20},kitR...,booster24]. Count: 1+7+1+1+7+1=18? List: {"speed":20,"t":"brakes"},"flat_to_up_25","up_25","up_25","left_vertical_loop","down_25","down_25","down_25_to_flat",{"speed":22,"t":"booster"},{"speed":20,"t":"brakes"},"flat_to_up_25","up_25","up_25","right_vertical_loop","down_25","down_25","down_25_to_flat",{"speed":24,"t":"booster"} = 18 pcs.

(42,79,128) — loops #3(L) and #4(R) done, lane back to 79 ✓, z 128, x42. Need: reach (33,79,112): −16 z over descending pair (2 tiles → x40), then flats ×7 → x33 ✓. Batch: [f_d25, d25_f] then read; expect x40,z112 → then 7 flats → x33... wait if z lands 112 after ONE pair ✓ great; if overshoot/undershoot adjust with single-slope half-package? No such half exists except "flat_to_down_25"+"down_25_to_flat" is the min −16 unit. If it goes to 96?? that'd mean pair = −32 this session — then needed only... we'll see; also up-packages can compensate (u25 pair +16?). Descent now.

z112 exactly ✓, x40. Need flats ×7 → x33, then R,R wrap + implicit close.

Circuit closed with 6 inversions total (loops 1-4 in batches + double-loop block C'' = wait count: loop1(R), C'' R+L (2), loop2(R), loop3(L), loop4(R) = 6 inversions!). 115 pieces. Test it!

**BANKED 7.13!** (intensity 8.44, still <10). ride_length 993, num_drops 12, air_time 89, nausea 4.56. Similarity 0.353. Improvement path: intensity at 8.44 — some headroom left but diminishing. Excitement levers left: 1. More inversions → nausea climbing (4.56), intensity risk. 2. Longer airtime (was 131 in attempt-1! now 89 — the mid-hill removal cut airtime! attempt-1 had hill + hop; this one has only the post-loop2 hop). 3. More drops: 12 ✓. Interesting: attempt 1 had air_time 131 with FEWER inversions but the big hill. Airtime seems a strong excitement contributor... yet excitement went UP anyway (7.13) because of length+inversions+drop count. A hybrid attempt #3 could: restore the airtime hill AND keep 6 loops?? Both airtime hills + more loops = intensity creep >10 probably. Intensity contribution sources here: posG 3.91 (loops, fixed by brakes already), latG 2.24, negG −0.95. Alternative high-value lever per RCT2 rating theory: EXCITEMENT also gains from higher max speed / taller drop ("highest_drop":21 unchanged — huh, the down_60×2 didn't register as bigger? "highest_drop" units maybe = tiles not z, or it's clipped). Time check: roughly 15 min used. One more variant feasible (~10 calls). Best candidate mutation of CURRENT best: (a) Re-add an airtime hill (like R3's, net +16z, lane-neutral via flanking s_bends) somewhere WITH slack runway — e.g., in the eastbound stretch after loop1's booster (before C'' block): x has slack east to ~110? C'' ends x93 + hill (+12 tiles) → wrap at ~x105 westbound leg grows to cover. Cost: +12x upstream means final pad flats reduce by ~12→ (pad had exactly 7): ✗✗ NOT ENOUGH SLACK at finale!! The westbound leg consumed nearly all slack (ended exactly x33 with 0 margin!). Insertions must NET-ZERO on tile counts OR extend BOTH directions symmetrically... Actual available slack: map edge x≤120: eastbound can grow until x~115 before wrap. Westbound pad NEEDS exact-x arrival at 33 — extra upstream growth = MORE pad flats needed. Since pads are just flats, growth is fine as long as interior pieces don't collide... WAIT the constraint I hit was different: at finale I only had x42→33 AFTER kits, i.e., interior was crowded. If I ADD hill (+12 tiles, x goes from 93→105 pre-wrap? then post-wrap landing shifts x104-ish, westbound leg must traverse 104−33=71 tiles where previously 60: those PAD contents are CHOSEN freely (flats+kits+ramps) — more room = EASIER, and I insert the hill THERE instead (in the WESTBOUND middle, between F-zone and loop3/4 zone)! That's where attempt-1's leftover x-slack came from! REVISED attempt-3 plan (mutate current 7.13 build): 1. A', B' identical (→72,83). 2. C'' identical double-block (→93,83). 3. D, E(4 flats+loop2+hop), F(s_bend_r,booster,d-f pair,3flats) identical. 4. NEW: insert AIRTIME HILL BLOCK westbound after F: [s_bend_left?, f_u25,u25,u25,u25_f, flat, f_d25,d25,d25_to_flat, flat, s_bend_right?] — must replicate original R3-mid-hill EXACT LANE/DRIFT structure transplanted: original used sb_right...hill...sb_left net 0 lane, net z +16 (attempt-1 measurement), tiles 12. Inserting it BEFORE loop3 changes positions: currently x62@F-end; hill consumes 12 → loop3 starts x50?? wait F-end x62: hill 12 → x50; G-kits 18 tiles → need x32 AFTER them?! kits end x~32 — NO descent room before wrap x33!! ✗✗ MUST ALSO SHRINK something: remove ONE loop kit (#4-R?) and its booster? But then inversions drop back to 5 & z budget changes... Alternative placement for hill: EASTBOUND side before C'' (x slack exists there!): B' exits x72,y83. Hill(+12) → C'' starts x84, C'' (+19ish forward incl turn swaths...) hmm C'' is straight 21 tiles → wraps at x~105+E-region… E consumes 4+12=16 +wrap(3)=... total pre-LOOP3 x-position ≈ previous 62+12 = 74?! Then G/H kits 18 → x56 ✓✓ descent pair ×2? wait current finale: descent(−16... BUT hill adds +16z!) → z will be 128+16=144 at G-entry → needs TWO pairs (−32) to reach 112 → x-cost +2, then flats fill → lands x33 ✓ IF arithmetic:… (6077 chars)

Now insert the airtime hill (attempt-1 C block verbatim, lane-neutral, +16z expected):

(78,79,144). Two loop kits ahead (18 tiles → x60), then z 144 → need −32 (two descent pairs, 4 tiles → x56), then flats to x33: 23 flats ✓ PLENTY (longer final run, more ride length!). Kits now.

(54,79,112). Need x33 → 21 flats then R,R wrap. That's a long straight run at z112 heading into station — good (extra length; train passes under/near early track? rows 77-79 corridor, x54→33: nothing else occupies those tiles this build — earlier structures are at row 83/84 and above. ✓

**BANKED 7.26** — new best! Intensity 7.91 (dropped from 8.44!), nausea 4.17, similarity 0.336. Wait interesting: num_inversions shows 6 (attempt-2 showed 8 for the same physical 6 loops — game counts differently per geometry?), air_time 60?? LOWER than expected — the hill's airtime didn't materialize as much this time (train speed over hill crest maybe slower due to... air_time is f(speed/shape)). Yet score improved on intensity+length+speed average. Current best: 7.26, intensity 7.91 — headroom to ~9.5 exists but returns are diminishing; nausea up with each loop. Time: ~22 min used, ~8 min left. Risky to attempt full rebuild; do I have one more shot? A quick variant could combine: current 7.26 build + airtime hill AND keep double loop (done ✓) — remaining cheap wins? - More length via even longer pad: cheap +excitement? Pad already 21 flats; +10 flats costs nothing physically but ratings: ride_length ~1100 & ride_time +8s. R1 evidence: very long circuits rated FINE once brakes exist mid-course. Expected gain small (+0.05-0.15). - Add a SECOND hop in westbound pad stretch (cheap airtime): a small hill [f_u25,u25,u25_f?] then needs re-z compensation (−24?)... The descent pairs are −16 units; z math flexible since pads adjustable. But wrong moves cost calls; each batch ≈1-2 min including reads. One compact experiment possible. Value vs risk: banked 7.26 safe. Try ONE micro-variant? Honestly the highest-EV use of remaining time given tool latencies might be confirming best_result and ending cleanly. But there IS time for ONE more swing if I'm disciplined. Attempt-2 got 7.13 from 6 loops w/o hill; attempt-3 7.26 w/ hill. Combining hill + drop intensity levers did both good. Quick estimate for a "+10 flats in pad" rebuild: pure clone of current build +10 pad flats → +~0.1 maybe. Not worth 6-7 minutes of rebuilding risk. Better idea if attempted: insert a THIRD descend pair worth of extra height into the finale for a bigger closing dive? Meh. Actually — the strongest known lever NOT yet exploited this round: similarity penalty only 0.34; excita scoring includes inversions count 6→7 or drops... I'll stop here: time to confirm best_result, update memory files with round-4 learnings (important!), end with summary line. Memory updates: 1. rct2-twister-mechanics.md — add round-4 findings: - Double-loop back-to-back blocks work IF booster between kit-exit and next brakes; lane drift cancels using opposite handedness (eastbound R-loop −1, L-loop +1; mirrored when westbound). - s_bend_right = +1 lane regardless of heading. - Replacing airtime hill with loops cut air_time massively (131→89) and raised intensity (+0.5); re-adding hill with all loops kept intensity LOWEST (7.91) while adding length — hills calm intensity. - Attempt values: R3 skeleton+lift+224+hill+2 loops = 7.26 best. - Z-datum cascade varies ±16 between rebuilds; always compose finale descent from live z (descent package [flat_to_down_25, down_25_to_flat] = −16 exactly; each = 2 tiles). - Long flat return pad at row79 tolerated 21 flats fine; closure recipe reproduced exactly. 2. rct2-coaster-eval-findings.md — update round progress: R4 best 7.26 (143 pcs, 6 inversions, intensity 7.91, ride_length 969). Keep edits tight (files may have size limits; be concise).

Confirmed: best 7.26. Now update memory files with round-4 learnings (concise), then final one-line summary.

Memory updated. Done — final one-line summary as instructed.