L-system tree · hy4

We need build index.html single self-contained referencing p5.min.js. Need inspect files. Need think carefully requirements and browser checks. Need use tools. Need likely create robust p5 L-system tree with progressive growth and wind attached children. We have ~15 min. Need write code and test with browser. Let's inspect directory and perhaps p5 version.

Need design implementation.

We need L-system explicit axiom/rules/angle, expansion bounded, connected trunk/branches, progressive growth trunk to tips, sway wind with child branches attached. Generation 1-5 control and Regrow. Changing gen or regrow restarts growth same grammar. Whole tree visible every gen. Procedural graphics leaves colors.

Need likely make visual appealing too. Need browser inspect initial output and console, sample branch growth and connections, gen change restart different structure, wind motion if complete. We can include debug hooks perhaps `window.__treeDebug` with snapshots for programmatic inspection (browser tool inspect perhaps evaluate? Need understand browser tool actions). We can use browser inspect to get DOM/console maybe no evaluate JS beyond perhaps screenshot. Can use actions screenshot, click, type, etc. Could expose debug info in DOM status text and use inspect. Maybe read tool response reveals DOM.

Let's design architecture.

L-system grammar with bracketed stochastic? Need explicit deterministic production rules. Use axiom "X" and rules X -> F[+X][-X]FX maybe F -> FF leads explosive growth. Need bound length. For 5 generations fit. Classic:
axiom X
X -> F[+X][-X]FX
F -> FF
angle 25 degrees
At n=5 huge string perhaps manageable: X recurrence: X count triples? Let's derive command count. F->FF and X replacement with 3 F? Actually "F[+X][-X]FX" includes F,F? F first + F before X =2 F, and 3 X. Number F doubles plus 2*X count. X count 3^n. For n=5 X 243, F count recurrence F_{n+1}=2F+2X_n. F0=0 X0=1. n1 F2; n2 F=4+6=10; n3=20+18=38; n4=76+54=130; n5=260+162=422. Total ~422 F segments + 243 X markers + brackets ~? ~1500 symbols. Fine. But tree structure: Each X expansion causes F[+X][-X]F X along current direction, yields trunk with side branches and continuation. At gen5 lots of segments (422) and leaves at X endpoints (243), manageable. depth branches maybe 10? Step length scaling needs fit all generation.

Alternative grammar X -> F[+X]F[-X]+X perhaps; F -> FF.

Need connected trunk and branches. Turtle stack: `F` draws segment from current position to next; `[` saves state; `+`/`-` rotates; `]` restores. Need wind with child branches attached to parents: hierarchical segment tree, each segment knows parent index and base local angle, parent relative transform. A simple static list of segments with endpoints generated by turtle and animation mask by distance/time. For sway, need positions recompute from hierarchy where each branch's orientation is parent orientation + local angle + wind offset. If we interpret grammar commands and build segment graph, each F creates segment with parent = current turtle segment; relative turn = accumulated angle since parent's draw (e.g., `[` + `+` rotate then F). Need ensure child branches remain attached to parents by computing each segment start as parent endpoint (or stack state). Important: when encountering `[`, save current state; side branch(s) use parent segment. Then `]` restore. Need set local angle relative to parent orientation. Let's formalize.

Turtle state includes `parent` (index of segment at current point) and `heading` (absolute orientation when no wind) plus maybe accumulated relative rotations. When F:
- create segment with `parent = state.parent`; `relAngle = angleDiff(state.heading, parent.heading)`; base length maybe dependent on depth or generation.
- end point = start + len*dir(heading)
- set state.parent = segment index; state.heading remains.
When +/-: update state.heading.
When `[`: push copy of state.
When `]`: restore.
Then for each segment, starting point is parent.end (if parent >=0), and worldHeading = parent.worldHeading + relAngle + wind deflection perhaps. But note parent.heading = base heading at time; child's relAngle should be difference between child base heading and parent's base heading. If rotations occurred after parent F and before child F, yes. Multiple F along same heading: each child's rel angle 0. Stacked nested branches: parent of branch from a segment is that segment. Fine.

However subtle: after `]` restores state to prior branch point, continuation F parent is the same parent segment and relAngle = state.heading - parent.heading = 0. Good. Branch child start at parent.end. For trunk continuation after side branches, parent = previous trunk segment. Fine.

Need wind: Want gentle sway while child branches stay attached. Each segment can have dynamic worldHeading computed recursively:
`worldAngle[parent] + relAngle + windDeflection(depth, segment, time)` where deflection perhaps small proportional to depth/flexibility and phase. If adding local deflection per segment, downstream children inherit cumulative angle, giving natural sway. Need keep tree whole visible at all times even wind. Calculate base geometry with deterministic lengths and fit using bounding box and scale. Wind can expand beyond slightly; reserve margin / conservative fit. Need perhaps wind deflection maximum ~0.015-0.035 radians per segment and cumulative branch depth maybe ~? Could lead endpoints shift. We can compute actual tree positions each frame and ensure margins; but scaling base to box with 15% margin likely enough. Or dynamic fit using theoretical min/max? Simpler choose branch lengths taper by depth in grammar maybe segment lengths small enough; fit base bounding box into canvas with margins and wind small. Need generation max tree visible. Also classic F->FF means trunk has 2^(n-1)? Actually F replacements cause long continuous trunks and branch lengths; scaling all F uniformly all generations gives enormous overall height at gen5 (maybe 32 segments trunk), and width. Scale should adapt per generation to fit: compute base geometry with unit step length per F, then find bbox and scale to fit canvas with margins, root anchor at bottom-ish. Need consider branch tips / leaf radius. Use scale = min((canvasWidth*0.78)/bboxWidth, (canvasHeight*0.78)/(bboxHeight)) perhaps. Then draw with transformed positions. Base anchor can be centered based on bbox or root fixed. A p5 canvas responsive. Need whole tree visible every generation; use computed geometry and fit.

But progressive growth from trunk to tips: Need animation per segment based on topological distance / path distance from root. We can assign progress order based on cumulative distance from root (e.g., `startDist = parent.endDist`, `endDist = parent.endDist + length`) and reveal segments over time from trunk toward tips. Need branches grow after their parent's endpoint and branch nodes. Use global growth value in "distance units", segment visible fraction `clamp((growth - startDist)/(length),0,1)`. Draw each segment from transformed parent endpoint to lerp along child direction for fraction. But if child segment starts only when parent fully grown: startDist = parent.endDist. Good. Need leaves perhaps at terminal X symbols or endpoints with no children. We can identify terminal segments / X markers. In grammar, "X" marker no drawing; when expansion n, X remain. We can record tip positions at state current point for each X command. But we need attach leaves to dynamic endpoints of parent segment. Collect `leafParents` when `X` encountered: parent index state.parent. Then when drawing, if growth beyond parent.endDist, leaf alpha/size grows. Yet many X at tips; note after expansion of X string at final iteration all X symbols correspond tips. Could also place leaf at every terminal segment (no children). Need maybe use X markers for exact tip positions. Both fine. Need ensure leaves attached to parent endpoint and sway along with it.

Potential issue using `F -> FF` doubles every existing F per generation, and branch lengths in unit steps vary by generation; scaling handles. Need bound grammar expansion. Explicit cap e.g. `MAX_SYMBOLS = 200000`, stop expanding or limit string to cap. At n5 ~? small. Need perhaps grammar generation function loops from 1 to n; if next length exceeds cap, truncate at safe bracket boundary? We can simply stop expansion and mark bound, but "generation control from 1 to 5" and "Bound grammar expansion" likely means avoid exceeding max. Could implement explicit MAX_SYMBOLS; if next would exceed, don't expand (or truncate safely). Given n5 safe under cap, no issue. Better robust safe truncation at bracket balance. But if truncating mid grammar, could produce malformed stack. Instead build string with `if (out.length + rule.length > MAX_SYMBOLS) break` and maintain bracket depth? Could choose cap 120000 well over expected, return unexpanded current generation if limit. Explicit. Need maybe expose stats in status text. Could mention cap.

Need generation control from 1 to 5. Could use `<select id="generation">` 1..5 and `<button id="regrow">Regrow</button>`. Use plain local script tag for p5.min.js. Use p5 global mode `setup`, `draw`. Need no external assets/network. CSS inline. Need perhaps attractive UI: full-viewport canvas with dark gradient background drawn procedurally (CSS gradient behind transparent canvas maybe) and control panel. Include moon/sun, ground, stars drawn p5 procedural. Need leaves colors. Need responsive.

Need think browser tool capabilities: likely run index.html via browser, screenshot at 1200x800. We can use click/type/key to interact. Need programmatic inspection maybe `browser inspect` returns DOM and console. Might add debug text to DOM showing stats and phase, and perhaps data attributes (segments, growth, etc.) so we can inspect. Could also use `window.treeDebug` but no eval tool. `inspect` maybe returns DOM including hidden debug element. We can write code to update a visible status with numeric values. Need be able to sample branch growth and parent-child connections. Could add hidden debug panel with current metrics and expose `window.__lsystem` object. Browser tool `inspect` likely dumps DOM/console maybe can use screenshot only. We can use screenshots at various times with motion frames. Need perhaps include an on-canvas debug overlay? Better write internal validation in JS that checks parent-child connection and updates DOM `#diagnostics`. Then inspect can read it. But requirement says "Verify: Sample branch growth ... inspect visible parent-child connections. Change generation ... If growth completed ... sample wind motion". As agent we need actually use browser tools to check. We can perhaps use `browser screenshot` repeated, and `browser motion` to see frames. Need perhaps use `browser inspect` to get console output. We can instrument console logs at intervals with growth and connection stats and wind offsets. Then browser inspect perhaps gives console. Need discover tool output format. We can call `browser inspect` on initial page after writing. Could include debug overlay. Need maybe use browser tools to click select and button. Let's plan.

Need implement high-quality tree geometry.

Let's derive grammar carefully:

Axiom: `X`
Rules:
`X -> F[+X][-X]FX`
`F -> FF`
Angle: 24° perhaps.

At gen1 string `F[+X][-X]FX`. Turtle:
F trunk segment 1
[+X] branch: + rotate -? (we'll decide coordinate angle; p5 y down, root direction -PI/2). `X` leaf marker at endpoint of F? Actually after F then `[`, save state. `+X`: rotate +angle and then X marker. No F under branch, so leaf marker at branch point itself with no segment. That would place leaf at trunk endpoint; no branch drawn. Next `[-X]` similarly. Then F continuation, X leaf marker. At gen1, side branches are leaves but no branch segments! At gen2, those X expand into F[+X][-X]FX inside brackets after rotation, so branch segments appear. This is classic. Fine, gen1 has just two trunk F segments and leaves at first node and tip. Does that satisfy branching structure? Perhaps generation 1 should show branch lines too. We can choose alternative grammar where gen1 already branches:
Axiom `F`
Rules `F -> F[+F]F[-F]F` maybe. This yields branches at each generation. But number might explode 5^n: n5 3125 F segments, fine. Rule explicit. More classic:
axiom `F`
rules `F -> FF-[-F+F+F]+[+F-F-F]`
angle 22.5°. At n5 string ~? 5^5=3125 F, manageable, but geometry has segments doubling each generation and branching; tree very bushy. Need hierarchy and fit. Could use this deterministic branching L-system (classic fractal plant) from Wikipedia. It draws connected trunk/branches because all F are segments with bracket stack. At each generation, each F expands to a whole small tree, producing recursive branching. But animation from trunk toward tips based on path distance gets complex and growth order: In string "FF-[-F+F+F]+[+F-F-F]", all F within rule may have varying path distances. Need parent tracking works. Nested branches whenever expansion happens; good. Segment lengths all equal in unit base; n5 trunk has 2^5 =32 vertical steps, branches nested, bounding box moderate. Number segments 5^5=3125, fine. Leaves can be terminal segments or branch tips. Need generation 1 gives 5 F segments arranged main stem + 2 branch clusters. Good. Generation 5 gives 3125 segments maybe draw fine at 60fps with per-frame transforms. Leaves at terminal F segments ~? Could be many (maybe ~1000) but fine. Need cap. Use explicit MAX_SYMBOLS maybe 250000. Expansion string length recurrence: rule length maybe 17? At n5 ~17*5^4? Actually ~? 5 F plus brackets/rotations; length = 5L(n-1)+12, n5 ~? 5^5 initial F + 12*(5^5-1)/4 =3125+9372=12497, trivial. So safe. Could do generation 5 with 3125 segments. That yields rich tree. But all F segments have equal length; segments from prior generation are replaced with 5 segments, so branch shape scales ~2 per generation in trunk length; fit handles. Need depth in hierarchy maybe up to n? Actually branch stack nesting from substitutions; could be 10 or so. Wind cumulative can be controlled.

Alternative grammar with X controls side branches and F elongation gives 422 segments at n5, prettier and easier. We could modify axiom to `FX` perhaps so gen1 has branch segments? Let's think:
Axiom `FX`
Rules:
`F -> FF`
`X -> F[+X][-X]FX`
At g=0 would F X. For generations 1..5, starting iteration 1:
n1: `FF[+X][-X]FX`? Actually F->FF; X->F[+X][-X]FX; total string `FFF[+X][-X]FX`? Wait axiom FX -> FF + F[+X][-X]FX = `FFF[+X][-X]FX`. Leaves X at branch points no side F. Still no branch lines.
Could choose rule X -> `F[+FX][-FX]FX` so each branch has F segments:
`X -> F[+FX][-FX]FX`
`F -> FF`
At gen1: trunk F; branches +F X and -F X each with a segment; trunk continuation F X. Gives branching. At gen2, all F double and each X expands recursively. X count 3 per generation, F count recurrence F_{n+1}=2F_n+? rule has F count 4? string F [ + F X ] [ - F X ] F X = 4 Fs + 3 X. X count triples. F1=4, X1=3; F2=2*4+4*3=20, X=9; F3=40+36=76; F4=152+108=260; F5=520+324=844. Under 1000 segments. Good! Leaves marker X at each branch tip. Tree shape natural: every X expands into a main stem of 2? At final X markers are tip positions after F. Need note each `X` expansion contributes structure; at gen5 243 leaves + maybe terminal branch endpoints. Great. String length maybe under 10k.

But need parent-child relation with rotations and stack. Add `F -> FF`, so each F segment length same. At each X expansion, branches start at tip of first F and continuation after second F. Let's parse rule:
`F[+FX][-FX]FX`
Starting at state p:
F -> trunk seg A from p.
[ save state at A end, + rotate, F -> left branch seg B from A end, X marker at B end, ] restore to A end
[ save, - rotate, F -> right branch seg C from A end, X marker, ] restore
F -> continuation seg D from A end along original heading
X marker at D end.
At next generation, each F doubles (two collinear segments), and each X expands into a 4-segment mini tree at tips. So there are branches at tips recursively. That's elegant, tree-like. Number of segment hierarchy depth maybe n*2 (F doubling) + branches; ~10-15. We can taper widths by recursion depth/topological depth and maybe leaves at X markers. Need whole tree visible. Base F length unit; at gen5 longest path maybe F doubling leads 2^5 =32 trunk units plus branches, width perhaps moderate. Fits dynamically.

Could choose angle 27° and asymmetric wind. Need perhaps include slight deterministic variation in branch angle/length to avoid too mechanical while still grammar explicit. But child transform must preserve connection. We can add small procedural variation per segment based on index hash to `relAngle` and `length` (deterministic), but grammar's angle still explicit. However generation structure still from grammar. Use seeded PRNG for stable branch styling. Yet if requiring "same chosen grammar" on regrow, randomness could be interpreted as changing structure? Regrow restarts growth using same grammar; if procedural jitter fixed per generation and seed doesn't change, okay. Could regenerate color leaves randomly? Better keep deterministic across regrow. We can set a `seed` per generation deterministic, perhaps `seed = 1000 + gen*...`; Regrow uses same. But "same chosen grammar" maybe no need strict same exact tree geometry? Better deterministic: no random structural variation. Could use hash on segment ID for tiny deterministic variation that remains same on regrow. Need perhaps no random at all for clean verification. Sway can be smooth sin/cos based on time and segment depth.

Important subtle geometry: F->FF leads each F from previous generation replaced by two collinear F segments. Our parse creates segment parent chain. That's fine. But X at previous generation expands into more segments at tip. At final generation, X symbols remain and mark leaves. Need collect leaf parents. At n=1, 3 X markers at B,C,D tips. Good.

Need interpret maybe other commands:
- `+` turn right/clockwise by angle (p5 coordinate angle with 0 to right, y down; root heading -PI/2, + angle rotates toward right).
- `-` turn left.
- `[` push state
- `]` pop state.
- `F` draw segment
- `X` leaf marker.
Could add `!` width decrease? Not needed. Width based on `depth` and/or subtree size. Need connected trunk and branches; width hierarchy can be computed after parsing: each segment's `thickness` based on number of descendant segments ("Strahler" / subtree mass). Compute children list and recursive subtree counts; width = max(1, baseWidth * sqrt(descendants / maxDescendants)) perhaps. This makes trunk thicker and branch tips thin. Need ensure at gen1 connections obvious. Could compute `subtreeSize` recursively in parent index order since parent always earlier index; loop reverse and add to parent. Then thickness = lerp from min to max using sqrt(subtreeSize/maxSize) and depth; perhaps `w = 1 + 10 * pow(subtreeSize/maxSize, 0.55)`. With dynamic scale, strokeWeight should scale too or use pixel widths independent. Use width in pixels based on canvas and generation; perhaps `maxWidth = min(18, 6 + generation*2)`; `w = max(0.8, maxWidth * pow(subtreeSize/maxSub, 0.42))`. At gen5 trunk ~16 px, tips ~1 px. Need leaves maybe circles/ellipses.

Growth:
- parse into segments with `startD = parent.endD` and `length = 1` (or perhaps modified by level/depth). For uniform F segments use len 1. But side branch lengths equal trunk segments; tree might look too sparse. Could taper lengths by branch depth: identify `branchDepth` from number of `[` nesting and/or turn events. State can track `branchLevel`: increment on `[`, decrement on `]`? Actually nested brackets can be from replacing X at branch tips; branch level naturally increments at each `[`. We can set segment length = pow(0.88, branchLevel) maybe. But F->FF doubling means lower-level trunk remains long; child branches at tips shorten. Classic. Need state `level`, and on `[` push then increment level (or branch substate), on `]` restore. But parse code if push then set current.level++. For F, length = pow(0.86, state.level). This preserves parent-child connection because end lengths used for startD. Need calculate base coordinates using oriented vectors and lengths. With dynamic scale, all okay. Need potentially branch length tapering makes tree compact at higher gen. But fit handles. Could use 0.9 to avoid tiny branches at n5. Branch level can reach ~5. Nice.

Also add deterministic angle jitter: `relAngle` = difference heading - parentHeading. Could incorporate slight variation on F based on segment count to give organic feel, but then state heading needs update after F to match used angle? We can define segment `relAngle = state.heading - parentHeading + jitter`; then after F set state.heading = (parentBaseHeading + relAngle) ??? That would propagate jitter to subsequent segments and all children. Need careful. To preserve grammar angle and natural shape, simplest no jitter. Could bend continuous trunks with `bend` per segment: on F, add tiny sin-based turn to state.heading after drawing; but then children's relAngle includes bend. That is still procedural and grammar base. We can define `heading += bend` after F, where bend = deterministic small based on segment index and level. Then subsequent segment's parent heading is previous segment's base heading (which includes accumulated bend). Need store `baseHeading` on segment. When parse F, segment heading = state.heading + jitter (small), then set state.heading = segment heading + bend perhaps. Parent child relative angle computed to parent segment's heading. This can be fine. But to avoid complexity, no jitter. Sway provides motion.

Need wind attached:
Build each frame `positions` arrays (startX/Y/endX/Y, angle). Root parent = -1; root start at anchor. For each segment in parse order (parents earlier), compute:
- parentAngle = parent >=0 ? seg[parent].worldAngle : rootAngle
- local deflection = wind influence maybe `amp * sin(t*... + phase + depth*...) * (0.2 + flexibility)` where amplitude is small. But if we add deflection to each segment's orientation, all descendant segments inherit accumulated deflection via parentAngle. Need especially trunk sway gradually. If each segment has e.g. amp = 0.004 + 0.002*level and some move, cumulative 10 segments ~0.06 rad (3.4°), natural. Need avoid large at tips. Could define `wind = windStrength * sin(time*1.2 - depth*0.22 + phase) * (0.3 + 0.7*depth/maxDepth)`, and add to local angle per segment. But if every segment gets independent sign based on depth, cumulative maybe chaotic but gentle. Perhaps simpler:
  `globalWind = sin(t*0.9) * 0.015 + sin(t*1.7+0.8)*0.006`
  Each segment adds `globalWind * flex`, where flex = 0.55 + 0.12*level or depth. Then cumulative along path yields 0.015 * segments, could be 0.5 rad for 32 segments—too much. Need divide by path depth or max depth. We could apply per-segment bend amplitude `0.0015` so 32 segments ~0.048 rad (2.7°). That's good. Branches nested maybe 10, additional ~0.015. Define wind deflection per segment = `0.0015 * windWave * (1 + 0.25*level)`. Add a bit of phase per segment/depth to create differential flutter: `wave = sin(t*1.1 - depth*0.18 + hash*0.3)`. But then parent angle inheritance may lead subtle differences. Need avoid static tree changing when growth not complete? Wind should start once grown. Requirement "Once grown, tree sways gently in the wind". We can enable wind after growth completes, with `windBlend` easing 0->1 over e.g. 1.5 sec after complete. During growth perhaps no wind or minimal. This helps sample growth static parent-child connections. Need maybe progressive growth with time. At start animate from 0 to maxD in ~7-9 seconds depending generation. Could choose fixed 7.5 seconds so checks can sample within. For gen5 more complex but still visible. Growth animation starts from trunk to tips based on path distance. Since maxD varies by generation (around 32), if fixed duration, speed scales to maxD/duration. Fine.

Need draw partial segment:
- compute full dynamic start and end from hierarchy. For each seg with growth fraction f. If f>0, endpoint = lerp(start,end,f). But note a child segment only starts when parent full. Need also width perhaps scale with f? Keep full width, maybe cap rounded.
- Use `line` with stroke color based on level / thickness, e.g. brown gradient from dark trunk to warm branch. Could use `stroke` per segment (3125* maybe 844, fine). p5 line with round caps? p5 `strokeCap(ROUND)`.
- For connected look, maybe draw curve? Straight segments with slight bend okay. Because parent end = child start, lines connect. Need roots at anchor.
- Need draw leaves at X markers when parent is fully grown. But some X markers are at branch tips; each may attach to segment. For leaves, need dynamic position: use parent segment's computed endpoint (which includes wind). Need scale up with growth after parent end. `leafProgress = clamp((growth - parent.endD - 0.2)/1.2)`, perhaps growth measured in length units; if maxD ~32, leaves appear gradually. Use ellipse/rhombus oriented along parent worldAngle. Need maybe avoid huge leaf count? 243 leaves, fine. Could add clusters of 2-3 leaves per marker? Maybe 1-2. Use deterministic color from index (greens/gold). At gen5 243 leaves. Gen maybe 3^5=243; expected. Could cap leaves to e.g. 1200. Fine. Need perhaps terminal F segments without X? Rule X produces leaves at all tips; no F after final X except interior, so all terminal segments have X marker. Good.

Could draw "buds" at active growth tips for visual growth: small glowing dots at endpoints of partially grown segments. Not required but nice. Need perhaps add to show progress. Could perhaps draw a few. But no need.

Need ensure parent-child connection under wind. Our `positions` computed all segments, including not yet grown, based on parent full endpoints. For partial segment, child's start is parent's full end regardless of growth. But child is not drawn until parent's full end reached (`startD=parent.endD`), so by then parent drawn full. Great. Under wind, child start uses parent full transformed endpoint, so attached. We can instrument connection check: for every drawn child with f>0 and parent f>=1, `dist(child.start, parent.end) < 0.001` (scaled). Since start computed from parent.end, always true. Could count visible joints. Need update diagnostics with this number and max gap. Could log at representative phases.

Need maybe dynamic fit:
- parse base geometry using heading/relAngle and lengths in "world units". Need handle root and base heading. We can compute all base endpoints by recursion with no wind (worldAngle = parentAngle+relAngle). Use positions `bx,by` in base units. Root at (0,0), rootAngle = -PI/2. Need find minX,maxX,minY,maxY including perhaps leaf radius.
- Compute fit scale: canvas area maybe full window minus UI overlay; tree could be centered in canvas. Canvas covers viewport. Use margins: top 90 (for panel?), bottom 80, left 80, right 80. Need tree not hidden behind control panel. Could place controls top left and tree center lower; header maybe top right. We can reserve top 120. At 1200x800, canvas tree area from y=100 to y=720; width 1100. Use actual. Need root at bottom of bbox. Formula map base coordinates to screen:
  `scale = min((w - 2*marginX)/bboxW, (h - topMargin - bottomMargin)/bboxH, maybe max?)`
  Use `originX = w/2 - ((minX+maxX)/2)*scale` (center bbox horizontally)
  `originY = h - bottomMargin - maxY*scale`? Since root y=0 and tree y negative mostly; maxY likely 0 (or branch down weird? angle ~25°, all upward maybe positive y from diagonal? Actually p5 y down, root -PI/2 -> up negative y. + angle still upward right; - angle upward left; all y negative until nested turns maybe some branches turn enough downward after repeated +/-? Could be. maxY likely 0. We can use `originY = h - bottomMargin - maxY*scale`, making bottommost bbox at h-bottomMargin. Root may be at that point if maxY=0. Then top at `h-bottomMargin - (maxY-minY)*scale`, which should be >= topMargin by scale. Need also center vertical perhaps. Good.
  For larger tree, scale maybe 10-20 px/unit. Need cap scale maybe 38 so gen1 not gigantic? Whole tree visible but could be too large; fit will scale to max area and gen1 might become huge, maybe okay but trunk stroke thick. We can cap to e.g. 36 or 42 to keep gen1 nice. Need top and bottom: if gen1 bboxHeight ~3, scale capped 42 -> tree 126px high, perhaps too small. Maybe cap 80 for gen1. Could use `min(fitScale, 84)`; gen1 ~3*84=252px, nice. Gen5 bbox maybe ~30*20=600px, fits. Fine.
  Need ensure wind doesn't push beyond margins. Use safety factor 0.88 on fitScale and reserve margins. E.g. `scale = min(...) * 0.88`. Could make topMargin 110, bottomMargin 85, side 100. At 1200x800: available 1000 x 605. Tree H <= 533, leaves radius etc. Wind small. Fine.

Need account leaf size in fit bounding box; add margin in world units perhaps `leafRadiusWorld = 0.6`. But leaves drawn in pixels (5-9), can just reserve 15 px side/top. Fit factor 0.86. Fine.

Need dynamically recompute fit on windowResized and generation change. p5 canvas resize. Need perhaps preserve growth progress on resize; just recompute scale.

Need UI DOM:
```
<div id="ui">
  <div class="eyebrow">Procedural L-System</div>
  <h1>Windborne Tree</h1>
  <div class="controls">
    <label for=generation>Generation <span id=genValue>3</span></label>
    <select id=generation>... 1..5 ...</select>
    <button id=regrow>↻ Regrow</button>
  </div>
  <div class="legend">
    <span id=state>Growing...</span>
    <span id=stats>...</span>
  </div>
  <div class="grammar">... maybe axiom/rule/angle ...</div>
</div>
<div id="debug" aria-hidden="true"></div>
```
Need perhaps no external fonts; use system font stack. CSS gradient background? p5 canvas draws background; control panel styled translucent. Use pointer events appropriately.
Could include slider? Select is enough. Need generation control from 1 to 5; select works. Could use buttons 1-5 maybe easier browser click. Select interaction via browser click/type maybe difficult; perhaps use radio-like buttons or range slider. Requirement control from 1 to5. A `<input type="range" min=1 max=5 step=1>` is easy via drag/key. Or five buttons. Better use five small buttons with data-gen. Then browser click at coordinates straightforward. Also can include `<select>` hidden? Need no need. A range slider with label and numeric badge gives accessible control. Browser tool `drag` can set. But to test change generation, pressing key on range might work if focused. Five buttons allow single click at x. Let's do segmented generation buttons `1 2 3 4 5`, plus Regrow. That's explicitly generation control from 1 to5. Need maintain selected style. Could also include range for semantics? Buttons okay. Add `aria-pressed`.

Maybe UI panel top center/left; need avoid tree. Use top-left with width ~330. Browser clicks coordinates e.g. 90+gen*? Need inspect screenshot to locate. Could use `<select>` and browser type maybe. Buttons easier.

Need debug panel updates:
```
<div id="diagnostics" data-phase=... data-grown=...>
  phase: growing | swaying
  growth: 42%
  segments: 844
  visible: ...
  joints: ...
  maxJointGap: 0.000
  windOffset: ...
</div>
```
Can make small monospace bottom right, maybe visible but subtle. Could use this as status. Need perhaps browser inspect returns text. Add data attributes on `body` or `#app`: `data-generation`, `data-phase`, `data-growth`, `data-segments`, `data-visible-segments`, `data-connected-joints`, `data-max-joint-gap`, `data-wind-offset`, `data-sway-frame`. This allows programmatic DOM inspect if tool dumps attributes. Need also console logs at milestones:
- On build: `console.log('[LSystem] built gen=... symbols=... segments=... leaves=... maxDepth=...')`
- During growth at 0, 25, 50, 75, 100% maybe log `[LSystem] growth 25% visibleSegments=... parentChildJoints=... maxGap=...`.
- On completion: log `[LSystem] complete gen=... entering wind`.
- During wind at times 0.5, 1.5, 2.5 sec after complete: log `[LSystem] wind sample ... tipX=... tipY=... delta=... attachedJoints...`.
This helps browser inspect console. Need avoid too many logs. Use state flags.

Need perhaps include `window.__treeDebug = { snapshot(){ ... }, setGeneration(n), regrow(), finishGrowth() }` for potential manual verification. But browser tool may not allow JS eval. Could include keyboard shortcuts to accelerate growth/wind perhaps. Useful for inspection within time: pressing `F` to finish growth? But requirement might be okay to add hidden debug shortcut. Could expose via `window` and perhaps use browser tool `key` with `f`. Need not show in UI but can add key handling:
- Arrow left/right adjust generation
- `R` regrow
- `F` fast-forward growth to complete (debug maybe not disclosed). But using `F` could conflict with no. Could add `Space` to skip growth? Maybe not needed.
- `G` toggle? No.
Could set growth duration ~5.5 seconds so browser checks can wait via `motion` sampling. Need browser `motion` likely captures frames over some period. If duration too long, can sample growth. Once complete, wind can be sampled. Total 7 sec + wind. Fine.

Need maybe have `window.__lsystemTest` object with functions to set growth to certain fractions and get geometry for verification. Since no direct eval, not useful unless browser tool can run JS via text/console. But perhaps browser action `inspect` gives a JS eval field? No schema only action, coordinates, text etc. `key` can trigger debug shortcuts. Could implement key commands that jump growth fraction:
- `1`..`5` select gen
- `r` regrow
- `f` complete growth
- maybe `,` or `.`? Not necessary.
Could use browser `key` with `f` to finish growth, then `motion` to sample wind. Need perhaps key events from p5 `keyPressed` can handle. Add accessible note? Maybe not.

Need perhaps use p5 global mode with functions defined in inline script. Need ensure script order: `<script src="p5.min.js"></script>` then `<script>...`. The runner inline p5 script into final artifact presumably. Need no external.

Potential p5 issues:
- Need avoid p5 `angleMode` default radians; use radians.
- `createCanvas(windowWidth, windowHeight)` maybe use `window.innerWidth`; p5 global `windowWidth` okay.
- `pixelDensity(Math.min(2, window.devicePixelRatio || 1))` maybe.
- `frameRate(60)`.
- `background()` with gradient? p5 no linear gradient easily; can draw horizontal lines with lerpColor each frame, 800 lines (fine) but could be expensive. Better use CSS background gradient and `clear()` each frame? Canvas transparent, CSS background visible. p5 `clear()` resets and redraws procedural stars/ground. Need perhaps no `background`. If use `clear()`, canvas alpha transparent, body CSS gradient behind. Good. Draw stars, moon, ground as shapes. On each frame, `clear()` then draw background accents (stars static positions deterministic). Need perhaps CSS radial gradients. p5 canvas transparent catches UI behind? UI z-index higher. Fine.

- Need need p5 `resizeCanvas` on windowResized.
- Need use DOM elements via `document.getElementById`.
- Need `select` maybe no.

- Need seed deterministic star positions using custom PRNG, not p5 random? Could use `randomSeed()` in setup and store. But p5's `random()` okay deterministic if seed set. Need avoid `noise` maybe. For star positions generate normalized. Use custom hash to avoid p5 instance setup concerns. Could simply use golden ratio sequences.

Need tree construction details in JS.

Let's define constants:
```
const GRAMMAR = {
  axiom: "X",
  rules: { X: "F[+FX][-FX]FX", F: "FF" },
  angle: 26 * Math.PI/180,
  maxSymbols: 120000
};
const MAX_GENERATION = 5;
const GROW_SECONDS = 6.2; // maybe 6.5
```
Need generation 1..5. `expand(generation)`:
```
let s=GRAMMAR.axiom;
for (let g=0;g<generation;g++){
 let next="";
 for (const ch of s) {
  const repl=GRAMMAR.rules[ch] || ch;
  if (next.length + repl.length > MAX_SYMBOLS) { capped=true; break; }
  next += repl;
 }
 if (capped) { // Need safely balanced brackets. Could stop at last balanced prefix
    s = balancedPrefix(next); break;
 }
 s=next;
}
return {sentence:s,capped};
```
Because cap never reached at n5, simple. If capped, need stack balance:
```
function balance(s) {
 let depth=0,last=0;
 for i... if '[' depth++; if ']' {depth--; if depth===0 last=i+1;}
 return s.slice(0,last || find last safe point);
}
```
But can just not apply partial iteration if cap: `if (wouldExceed) { capped=true; break outer; }` and keep previous `s` (balanced). Need build next only if entire iteration fits; estimate length via total maybe. Use pre-count:
```
let estimated=0; for ch of s estimated += (rules[ch]||ch).length;
if (estimated > MAX_SYMBOLS) { capped=true; break; }
...
```
Then s remains balanced. Good.

At gen5 estimated maybe under 10k. Good.

Parse:
Need state object:
```
let state = {heading: -Math.PI/2, parent: -1, level:0};
let stack=[];
let segments=[];
let leaves=[];
let maxDepth=0;
for (let i=0; i<sentence.length; i++) {
 switch(ch):
 case 'F': {
   const parentHeading = state.parent >=0 ? segments[state.parent].baseHeading : ROOT_ANGLE;
   const parentEnd = state.parent>=0 ? segments[state.parent].endD : 0;
   const len = Math.pow(0.90, state.level); // branch level
   // perhaps tiny deterministic curvature on heading, but keep.
   const heading = state.heading; 
   const relAngle = normalizeAngle(heading - parentHeading);
   const depth = parent>=0 ? segments[parent].depth+1 : 0;
   const seg = {parent, relAngle, length:len, startD: parentEnd, endD: parentEnd+len, level:state.level, depth, ...};
   // base coordinates:
   const startX = parent>=0 ? seg[parent].bx2 : 0, startY ...
   seg.bx1=...; seg.bx2=...; ...
   seg.baseHeading = heading;
   state.parent = idx;
   state.heading = heading; // no bend
   segments.push(seg)
   break;
 }
 case '+': state.heading += angle; break;
 case '-': state.heading -= angle; break;
 case '[': stack.push({...state}); state.level +=1; break; // careful: push old state, then mutate same object? If stack.push(state) and then mutate, stack reference changes. Need push copy, then state = {...state, level: state.level+1} perhaps.
 case ']': state = stack.pop() || state; break;
 case 'X': leaves.push({parent: state.parent, id: leaves.length,...}); break;
}
```
Need consider bracket nesting: We push current state on `[`, then increase level for current state. On `]`, restore. Good. But if nested brackets, level increments. Need ensure `level` of F at first branch is 1, second branch is 1 (restored from saved state level 0 then increment again). Fine. At X expansion, X markers after F remain at their branch level. At next iteration, those X are replaced with structure containing new brackets that increment from that level. So level path can grow (branch level) by generation. Good. Need maybe max level 5.

Need issue with `state.parent` after `]`: saved state includes parent segment and heading at branch point. Side branch F draws from that parent. Then restore returns parent to branch point segment. continuation F draws from same parent. Good.

Need collect leaves at X. Some X markers might occur where `state.parent` is -1? Because axiom X with generation 0 only, but gen>=1 no. Fine. Need maybe duplicates same parent from `[-FX]` etc? Each X after an F has unique parent segment. Fine.

Need base geometry:
```
if parent>=0:
  seg.bx1 = parent.bx2; seg.by1 = parent.by2;
else 0,0
seg.bx2 = bx1 + cos(heading)*len; by2=...
```
Potential discrepancy under wind: `relAngle` computed relative to parent's `baseHeading`, but when no parent rootAngle = -PI/2. Then dynamic angle = parent worldAngle + relAngle + wind. Good.
Need parent heading for continuation after `]` where `state.parent` is segment A and state.heading = A.baseHeading. relAngle=0. For side branch with +angle, relAngle=+angle. Great.

Need normalize relAngle? Because heading can accumulate multiple turns; difference may exceed ±π? Angle ~26°, nested turns maybe could sum >π after many rotations. Could just keep raw difference; dynamic worldAngle can be whatever. Need ensure parent baseHeading from state. Use `heading` stored exact. `relAngle = heading - parentHeading`; no need normalize, because p5 trig handles. For root angle we set -PI/2. Fine.

Need perhaps add small "bend" after F to make trunk organic but state.heading same ensures no jitter. Wind supplies organic movement. Could add per-segment deterministic `bend`:
```
const bend = 0.012 * Math.sin(idx*1.7 + level) * (level? maybe)
state.heading += bend;
```
Then next segment's base heading changes; this is compatible. But grammar angle still explicit. It can make all branches slightly curved. Need relAngle calculation for child after bend: state.heading includes bend; parentHeading is seg.baseHeading (before bend). So next continuation segment relAngle = bend. Good. Side branches saved at state after bend? We push after F, state.heading includes bend, so branch base heading = parentHeading+bend±angle, relative angle includes bend±angle. Thus connected. Nice. Need maybe alternate sign by hash. Could define `bend = 0.006 * sin((idx+1)*2.399 + level*0.8)`; small. At 32 trunk segments cumulative maybe ~0.0 due oscillation. This adds procedural organic feel. Is it "same chosen grammar"? yes. Need expose angle in UI. Could mention rules.

Need compute subtree sizes:
```
for seg children=0, subtree=1
for i = segments.length-1 downto 0:
 if parent>=0 { parent.subtree += seg.subtree; parent.children++ }
```
Because parent index always less than child index. Need maybe multiple children from same parent; okay.
`maxSubtree = segments[0].subtree` (root). Need terminal segments = children===0. We have leaves from X; likely equate.
Segment `order` = i.
`growthMax = max(seg.endD, parent.endD maybe)`; leaves appear after parent.endD. Need set maxGrowth = maxD + 1.2 (for leaf scale). But branch growth should complete maybe after all segments, then leaves grow during final ~0.8 distance. Need decide when phase "grown". Could define `growMax = maxD + 1`, and segment reveal uses `growth` capped at maxD; leaf progress uses `(growth - parent.endD)/1`. `growthNormalized = elapsed / GROW_SECONDS`; `growth = growthNormalized * (maxD + 1.0)`. Then when norm reaches 1, all segments and leaves are fully grown. Need draw branch fraction with `clamp((growth - seg.startD)/seg.length, 0,1)`. Since growth can exceed maxD, all full. Leaves progress `clamp((growth - parent.endD)/1.0,0,1)`; some leaves at inner branch tips appear earlier. Are X markers at all tips only after final iteration, so parent endD likely maxD near ~? some side branches shorter path maybe appear earlier, fine.

Need perhaps growth based on path distance from root, giving branches at the same distance grow simultaneously. Good. Need active tips glow at partial segments. Could identify segment with `0<f<1`, draw small circle at their temporary ends. Need perhaps if many, okay.

Need transform:
- For each frame, windBlend (0->1 after full growth). Need compute `windTime = (millis()-completeAt)/1000`; `windBlend = min(1, windTime/1.2)`.
- Need compute segments dynamic geometry each frame. Use arrays or attach to seg object:
```
function solveBranches(t, windBlend) {
 const baseRoot=-PI/2;
 for (let i=0;i<segments.length;i++){
   const s=segments[i];
   const parentAngle = s.parent>=0 ? segments[s.parent].angle : ROOT_ANGLE;
   const startX = s.parent>=0 ? segments[s.parent].x2 : rootX;
   const startY = ...
   const wave = Math.sin(t*1.15 - s.depth*0.13 + s.phase) + 0.35*Math.sin(t*2.1 - s.level*0.7);
   const flex = 0.6 + 0.18*s.level + 0.008*s.depth; // maybe 0.6-1.8
   const bend = windBlend * 0.0019 * wave * flex;
   const angle = parentAngle + s.relAngle + bend;
   const len = s.length*scale;
   s.x1=startX;... x2=startX+cos(angle)*len;...
   s.angle=angle;
 }
}
```
Potential issue: because parentAngle itself includes wind bend of parent, and each segment adds another bend, wind accumulates. With 32 trunk segments and wave similar phase per depth, cumulative ~32*0.002=0.064 rad, endpoint displacement maybe ~10-20px. Good. At gen1 only 4 segments, wind tiny ~0.008 rad, maybe barely visible. Need make gen1 sway visible: scale amplitude by `1 / sqrt(depthCount?)` or add global trunk lean at root that applies to all segments uniformly. Could apply a base wind angle at root: `rootAngle = ROOT_ANGLE + windBlend * (0.018*sin(t*0.9)+0.008*sin(t*1.7))`; all segments rotate around root, visible even gen1. Then local bend adds subtle branch flex. Whole tree sways as rigid-ish plus flexible tips. This preserves attachment. Need root shift maybe no (root anchored). Use:
```
const globalLean = windBlend * (0.022*sin(t*0.75) + 0.009*sin(t*1.45+1.2));
const parentAngle = parent>=0 ? parent.angle : ROOT_ANGLE + globalLean;
```
Then all branches attached. Wind offset sample can measure tip x changes from base positions. Need avoid tree clipping: globalLean 0.03 rad at height 500px -> 15px, plus flexible bends maybe 20px, safe margin 100px. Fine.

To create differential motion, local bend phase depends on depth/level; perhaps:
```
const wave = Math.sin(t*1.25 - s.depth*0.18 + s.phase*0.35) * 0.0025 + Math.sin(t*2.05 - s.level*0.6)*0.0008;
```
Need not overcomplicate.
Need perhaps compute `phase = hash(i)` deterministic. Use `hash01(i)` function. Need ensure no JS random each frame. Fine.

Need draw:
```
function draw() {
  clear();
  drawBackdrop();
  const now = millis()/1000 etc.
  updateGrowth();
  solveBranches();
  drawGroundShadow();
  drawSegments();
  drawLeaves();
  drawGrowthTips();
  updateDiagnostics();
}
```
Canvas transparency and `clear()` perhaps p5 `clear()` available. Use `noStroke()` etc.
Background accents:
- stars fixed positions based on viewport, maybe 50 small dots.
- moon at (w-100,100) with glow circles.
- horizon hills with bezier? p5 `beginShape`, `vertex`, `endShape(CLOSE)`. Draw after stars but before tree. Need perhaps use `fill(16,30,45,200)` etc. CSS background dark blue gradient.
- Ground line at h-70 maybe. Root at h-bottomMargin maybe h-85. Need match. draw ground ellipse shadow at root.

Need maybe UI panel overlays top left and status bottom right. p5 tree centered. Need maybe if tree bbox center shifted right due asymmetric branches, origin maps center bbox to canvas center. Good.

Need draw trunk/branches with color:
```
const warmth = s.level / maxLevel;
stroke(lerpColor(color(91,58,38), color(150,105,62), warmth));
strokeWeight(s.width * (0.65+0.35*f)? maybe no)
line(s.x1,s.y1,s.x1+(s.x2-s.x1)*f, ...)
```
Need perhaps `strokeCap(ROUND)`.
Need draw segment outlines? Could draw a dark wider underlay for trunk:
- First pass thick dark stroke, then second pass lighter narrower stroke? Might be expensive but okay. Could draw each segment with a single stroke. Need connections at joints; round caps help. For thicker parent to thin child, round caps form a smooth joint. Could draw subtle highlight lines for trunk segments with width >3: stroke color lighten and weight w*0.25, line offset? Maybe unnecessary.

Need avoid per-segment `color()` object allocation 844 times per frame; p5 color creation can be costly. Compute RGB numbers with simple lerp:
```
const k=s.level/maxLevel;
stroke(78+55*k, 50+42*k, 34+20*k, 235);
```
At trunk dark brown, tips amber. Need perhaps trunk more visible against dark background. Use (126,82,51) trunk, (178,130,76) tips. Good.
`strokeWeight(Math.max(0.8, s.width * Math.min(1, 0.45+0.55*f)))`? If partial segment, thickness full maybe okay. Need hidden segments. Use `f` >0.

Need leaf colors:
```
const hueMix = hash01(leaf.id*...);
const r = lerp(62, 190, etc), g = ...;
fill(r,g,b, 220*prog);
noStroke();
push(); translate(x,y); rotate(parentAngle + ...); ellipse/leaf shape
```
Use custom leaf shape with `beginShape` and `vertex`? Could draw ellipse rotated. Need maybe 243 leaves. Use p5 `ellipse` with `push/pop` per leaf; fine. Could use `quad`/bezier:
```
push(); translate(...); rotate(s.angle + leaf.angleOffset);
const sz = (5+3*hash)*prog*scaleFactor;
beginShape();
vertex(0,0);
bezierVertex(sz*.7,-sz*.5, sz*1.8,-sz*.2, sz*2.0,0);
bezierVertex(sz*1.8,sz*.2, sz*.7,sz*.5,0,0);
endShape(CLOSE);
pop();
```
This gives leaf with petiole at parent endpoint. Need perhaps leaf radius 6-10px, scale based on canvas maybe `leafScale = clamp(scale/18,0.7,1.25)`? Since base world len * scale ~15-30px, leaves ~10px. Use `leafSize = (4.5 + 3*hash)*clamp(scale/20,0.75,1.3)*leafProgress`. That's 6-10px. Fine. Need perhaps draw leaf vein as short line? Could skip. Need draw leaves after branches; ensure attached.

Need detect `leaf.parent` may be -1 or undefined; skip. Leaves should only draw when `f(parent)==1`; progress based on growth. Since all X final markers at tips, parent likely has no children. But if some parent has children? At final expansion, X no F after, so no children from that segment; okay. Could draw leaves at parent full endpoint. Need maybe color by level. Use gradient gold/green to look seasonal.

Need draw active growth tips:
- For each segment with 0<f<1, `fill(245,210,130,180)` `circle(endX,endY, 2.5)`.
- Could be many partial segments at a growth front (hundreds) at gen5; maybe okay. Need maybe draw only first 200. Not necessary.

Need draw "growth wave" perhaps no.

Diagnostics:
Need define `currentVisibleSegments`, `attachedJoints`, `maxJointGap`, `sampleTip`, `tipBaseX`, `tipBaseY`, `windSample`.
During draw after solve:
- visible segments count f>0
- connections count: for each visible child with f>=? and parent>=0 and parent full, compute `Math.hypot(seg.x1 - parent.x2, seg.y1 - parent.y2)`; max gap. Since static scale transform and solve, always 0. Need include only child f>0 (if growing) and parent f>=1; if child f>0 implies parent full. Count.
- wind offset: choose one leaf parent maybe last leaf or segment with max depth. Compute `dx = s.x2 - screenFromBase(s.bx2,s.by2)` and `dy`. Need map base: `screenX = originX+bx*scale`, `screenY=originY+by*scale`. Track `tipOffset = hypot(dx,dy)`. Need maybe sample dynamic tip x over time. Need log wind at intervals.
- Need update body dataset periodically maybe every frame:
```
document.body.dataset.generation = generation;
document.body.dataset.phase = ...
document.body.dataset.growth = (growthNorm*100).toFixed(1);
document.body.dataset.segments = segments.length;
document.body.dataset.visibleSegments = visible;
document.body.dataset.attachedJoints = attached;
document.body.dataset.maxJointGapPx = maxGap.toFixed(4);
document.body.dataset.windOffsetPx = tipOffset.toFixed(2);
document.body.dataset.symbols = sentence.length;
```
Could be expensive setting dataset each frame but fine. Update every 6 frames maybe. Need status text update every ~10 frames. Need keep DOM accurate. Could update each frame simple. Fine.

Need `console.log` milestones. Need ensure no console errors. On build:
```
console.log(`[L-system] gen ${generation}: ${sentence.length} symbols, ${segments.length} segments, ${leaves.length} leaves, generation cap ${MAX_SYMBOLS}`);
```
Growth logs at 0.25,0.5,0.75,1:
```
if (progress >= nextLog && ...) console.log(`[L-system] growth ${...} visible=${...} attached=${...} maxGap=${...}`);
```
Need `nextLog` array. On complete:
```
console.log(`[L-system] growth complete; wind engaged; ${...} parent-child joints connected`);
```
Wind sample at 0.8,1.8,2.8 sec:
```
console.log(`[L-system] wind sample ... tip=(${...}) base=(${...}) offset=${...}px attached=${...}`);
```
Need perhaps tip offset at sample times can be near zero if sine crosses zero. Use more than one sample and measure max offset. Could track `maxWindOffset` since complete. Log `maxOffset`. Also need visual motion via browser motion frames. Could choose root lean frequencies so at 0.8,1.8,2.8 different.

Need "sample wind motion" perhaps use debug keyboard shortcuts and data attributes. Could log tip positions at frames; use `window.__treeSamples` array accessible. Add `window.__lsystemDebug = { snapshot, finishGrowth, setGeneration, regrow }`. Browser tool maybe can inspect via console? Not sure. But data attributes enough.

Need keyboard shortcuts:
```
function keyPressed() {
 if (key >= '1' && key <= '5') setGeneration(Number(key));
 else if (key==='r'||key==='R') restart();
 else if (key==='f'||key==='F') { growthElapsed=GROW_SECONDS; ... } // fast-forward
}
```
Need p5 global `keyPressed` gets called. Also DOM buttons have click event listeners. Need perhaps prevent select? Buttons fine.
Need button labels:
```
<div class="gen-buttons" role="group" aria-label="Generation">
<button data-gen="1">1</button>...
</div>
<button id="regrow">Regrow</button>
```
Need update aria pressed/classes. Need on generation change call `buildTree(n, true)`. "Changing generation ... restarts growth using same chosen grammar." Yes. Need growth elapsed reset, wind off, milestone flags reset. Regrow same generation reset with same grammar. Need maybe `generation` selected default 3 or 4. Default 4 perhaps visually rich. At gen4, segments 260? Let's recalc with rule 4 F/3X and F doubling:
n0 F=0 X=1
n1 F=4 X=3
n2 F=2*4+4*3=20 X=9
n3 F=40+36=76 X=27
n4 F=152+108=260 X=81
n5 F=520+324=844 X=243.
Gen4 260 segments, nice. Default 4 perhaps tree medium. Need growth ~6.5 sec. For browser test, change to 5 and check restart and different structure. Start gen3 maybe 76 segments easier to see connected branches. But visual should be impressive. Default 4 gives 81 leaves and connected network. Fine.

Need "bound grammar expansion": cap 50000 perhaps; gen5 sentence perhaps calculate ~? Let's compute with rule length. Rule X string "F[+FX][-FX]FX": count characters: F(1) [ (2) +(3) F4 X5 ]6 [7 -8 F9 X10 ]11 F12 X13 =13. Rule F "FF" length2. String length recurrence L(n+1)=2*#F + 13*#X + other chars? Actually all characters are F,X,+,-,[,]; rules leave +,-,[,] unchanged. Let counts:
F_n rec as above; X_n=3^n; structural count S_n from previous S + 9*X_n? Rule X adds 4 `[`/`]`? 2 pairs=4 brackets, plus 2 turns =>6 structural. Actually string 13 =4F+3X+6 other. F rule adds 1 extra F but no structural. S_{n+1}=S_n +6*X_n. n0 S=0. n1=6; n2=6+18=24; n3=24+54=78; n4=78+162=240; n5=240+486=726. L_n=F+X+S: n5=844+243+726=1813. Very small! Great. Can cap 100000 safely. Need perhaps more elaborate grammar? 844 segments enough. Gen1 4 segments; maybe tree a bit sparse but okay. At gen5 844 segments rich. Good.

Need compute growth max distance considering branch level and F doubling; longest path maybe 2^5 main trunk segments times length1 =32, plus branches maybe ~? Level taper. Fine.

Need ensure all branches visible at gen5: fit based on base geometry. Need maybe positions can go down due angle nested; compute bbox from base coords. We can inspect with JS maybe run a Node script parsing grammar to estimate bbox. But in browser, data stats can show. Need build and screenshot.

Potential problem with F->FF and branch level: When an F segment is replaced by two collinear F segments, the second gets `level` same as replacement context. Good. But `X` at branch tip expands into F at branch level and nested branches at level+? We parse bracket state increment. Good. Need perhaps tree branch angle count can cause branches to point downward after multiple `+` rotations? At each expansion, a branch X at level1 expands into + branch at level2 etc. Since turns accumulate relative to parent, repeated + along a lineage can turn >90 degrees after 4 levels. angle 25° *4 =100°, so some branches point downward. That's natural, but bbox accounts. Need perhaps keep visible. Need avoid runaway long horizontal branches; fit accounts. The main trunk (X continuation) stays vertical. Side branches can curve through nested + or -, producing fractal fan. Good.

Need perhaps root at base with all branches drawn from root tip; gen1 trunk first F then side branches from its endpoint, so no branch at ground. Fine.

Need maybe branch thickness based on subtree sizes. Let's compute `root.subtree` = all segments, width max. Need root maybe first trunk F. `subtree` of continuation path includes all descendants; side branch segments also perhaps. Because parse order is depth-first: first trunk F parent of all; branch segments and continuation segments. Reverse accumulation works. Good.
Need `maxLevel = max(seg.level)`, `maxDepth = max(seg.depth)`.
Need width:
```
const ratio = Math.pow(s.subtree / rootSubtree, 0.42);
s.width = 1.0 + maxTrunkWidth*ratio;
```
But side branch with subtree 1 still width 2; too thick. Use `0.7 + maxW*ratio` maybe ratio for 1/844: pow(0.00118,0.42)=0.058, width 1.6 for maxW16; okay. Root width 16.7. Need scale with canvas height: `maxW = constrain(height*0.018, 8, 16)` perhaps. Gen1 root segments count4; width 14; okay.
Maybe use `Math.pow(ratio,0.65)` gives tips 0.01, width 0.9. Use exponent 0.55:
```
w=0.65+maxW*Math.pow(s.subtree/rootSubtree,0.55)
```
At 1/844 -> 0.024*16=0.38 ->1.03. Good. Nice taper.
Need stroke alpha 245.

Need draw segment maybe trunk smoother with lineJoin? p5 line doesn't join, round caps. Fine.

Need leaves dynamic under wind. Need map leaf parent endpoint `s.x2,s.y2` (full) even if growth not full; draw only if `leafProgress>0`. Need perhaps leaf attaches at full endpoint; yes. Need shape orientation based on `s.angle + leaf.offset`.
Need compute leaf color from hash:
```
const h = hash01(leaf.id*13.37+generation*7);
if (h<0.35) gold (224,170,72), else green (72,156,91), else teal...
```
Could use lerp. Need perhaps alpha 210*prog.
Need draw leaf shape:
```
const L = leafSize*(1+0.5*h);
push(); translate(x,y); rotate(angle + (h-.5)*1.2);
beginShape();
vertex(0,0);
bezierVertex(L*.3,-L*.45,L*1.25,-L*.35,L*1.65,0);
bezierVertex(L*1.25,L*.35,L*.3,L*.45,0,0);
endShape(CLOSE);
```
Need p5 `bezierVertex` in shape works. Maybe `ellipse(L,0,L*1.6,L*.7)` simpler and robust. But leaf shape more appealing. Use `beginShape` with `vertex`, `bezierVertex`; p5 supports. Need perhaps all leaves ~243, fine.
Need perhaps draw a tiny vein line with `stroke(255,255,255,45)` and line(0,0,L*1.35,0), but 243 extra lines; okay. Could skip.

Need ground shadow:
```
noStroke(); fill(0,0,0,60); ellipse(originX, originY+8, 140,18)
```
Need root coordinate maybe `rootX=originX`, `rootY=originY`, likely tree root at lower bound. But if maxY>0, originY chosen accordingly; need root coordinate compute from `fit.transform(0,0)`. Store `fit = {scale, ox, oy}`. For dynamic solve, root = `fit.ox,fit.oy`. Ground shadow perhaps at root. Need maybe ground line at `fit.oy+8`. But if root up because some branches go below, ground line at root +? Could be okay. Use fixed `groundY = height - 58` perhaps. But root perhaps `height-bottomMargin - maxY*scale`, if maxY 0 -> h-80. Ground line h-70. Fine. Need perhaps actual root at h-80. Good.

Need background hills:
```
fill(11,26,36,180);
beginShape();
vertex(0,h-72);
for x=0..w step40 vertex(x, h-95 - 18*sin(x*.006) -...);
vertex(w,h); vertex(0,h); endShape(CLOSE)
```
Need root at h-80, so hill top around h-100 may cover lower trunk? Draw background before tree, so tree visible. Ground line maybe. Fine.
Need stars fixed deterministic using normalized positions generated from `hash01(i*...)` but need update on resize; draw from normalized each frame. Use 70 stars. Need avoid overdraw too expensive. Fine.
Need moon glow at w-110,110 using concentric ellipses with low alpha. UI top-left doesn't overlap. Could use `drawingContext.createRadialGradient` maybe procedural but external no. Simpler concentric circles.

Need maybe p5 canvas CSS display block; body overflow hidden.

Need debug panel bottom right perhaps:
```
<div id="readout">
  <div id=phaseLabel>Growing</div>
  <div id=metrics>...</div>
  <div class=bar><span id=growthBar></span></div>
</div>
```
Need UI not too cluttered. Top-left panel with grammar:
```
<div class=rule><span>Axiom</span><code>X</code></div>
<div><code>X → F[+FX][-FX]FX</code></div>
<div><code>F → FF</code></div>
<div><code>θ = 26°</code></div>
```
Shows explicit grammar. Need maybe on small screens panel width. Use CSS media query. Need perhaps generation buttons.

Need perhaps `aria-live` status.

Need browser tests. We'll write file then reload and inspect. Need use browser tool actions. Might need first call browser reload. Let's create file.

Let's carefully write code.

Detailed JS:

```
(() => {
  'use strict';

  const GRAMMAR = Object.freeze({...});
  ...
  let generation = 4;
  let sentence = '';
  let segments = [];
  let leaves = [];
  let rootSubtree=1;
  let maxGrowthDistance=1;
  let fit = {scale:1, ox:0, oy:0, baseMinX...};
  let growthStart = 0;
  let growthElapsed =0;
  let completeAt = -1;
  let progress=0;
  let currentGrowth=0;
  let nextGrowthLog=0.25;
  let windLogs=[0.8,1.8,3.0,4.5];
  let nextWindLog=0;
  let lastFrameMs=0;
  let metrics = {...};

  window.setup = function(){ ... };
  window.draw = function(){ ... };
  window.windowResized = function(){...};
  window.keyPressed = function(){...};
```
Need p5 global mode requires functions on window; using `function setup()` at script top-level (not inside IIFE) might be global. If inside IIFE, assign `window.setup = ...`. p5 global mode looks for `window.setup` after load? p5.min.js already loaded; p5 instantiation happens on DOMContentLoaded or immediately after page parsing. If our script defines window.setup before DOM ready, fine. Need perhaps p5 global created after script parsing. Yes.

Could avoid IIFE and define global `function setup()`, `function draw()` etc. Need variables global with `let` (top-level script lexical not on window but functions can access). Fine. Simpler. But need `window.__lsystemDebug` assignment. Use top-level. Need avoid name collisions with p5 global functions (`key`, etc.). Fine.

Maybe p5 global mode initialization happens when document ready; our definitions are available. Good.

Need DOM listeners in setup. Need `window.setup` etc if top-level function declarations. Good.

Potential p5 function `clear()` might conflict with `Array.prototype`? no.
Potential global variable `frameCount` from p5 can be used. Need avoid declaring our own `frameCount`. Fine.
Potential global variable `width`, `height` from p5; avoid.
Potential global `angle` no.

Need ensure no use p5 before setup, e.g., custom `constrain` in build? We can write own clamp. Use `Math.min/max`.

Build tree on setup after DOM listeners. Need maybe `millis()` available in setup? p5 global millis available. Yes. But could use `performance.now()` to avoid p5 dependence. Use `performance.now()/1000` throughout. That's robust and allows debug. Growth based on wall time:
```
let now = performance.now()/1000;
let dt = Math.min(0.05, now-lastTime);
lastTime=now;
if (progress<1) growthElapsed += dt;
```
Need p5 tabs background issue: dt clamp to 0.05 means if tab hidden, growth pauses; fine. Need `growthElapsed = Math.min(GROW_SECONDS, growthElapsed+dt)`.
Need `windTime = progress>=1 ? (growthElapsed-GROW_SECONDS) + maybe extra accumulated?` If growthElapsed capped, windTime won't increase. Instead use separate `nowComplete` timestamp:
```
let completedAt = null;
if (progress<1) { growthElapsed += dt; if(...){completedAt=now; ...} }
let windTime = completedAt===null?0:now-completedAt;
```
Need if fast-forward key sets growthElapsed=GROW_SECONDS; draw next frame sets completedAt=now. Fine.
Need `windBlend = clamp(windTime/1.25,0,1)`.
Need `t=now` for wind phase. Could use windTime for local waves plus maybe absolute time; either fine. To avoid jump when complete, waves start at windTime=0 but windBlend ramps. Use `windTime` in sin. Good.
Need `windEnabled = windBlend>0`. Once grown, sways. Need tip offset from base; root lean at windBlend=0 zero.
Need if browser load and initial screenshot early, growth start at setup now. Fine.

Need build tree updates `growthElapsed=0; completedAt=null; nextGrowthLog=.25; nextWindLog=0; maxWindOffset=0;` and parse. Need maybe body dataset `generation`. Need log.

Need compute `maxGrowthDistance`:
```
maxEndD = Math.max(...segments.map(s=>s.endD))
maxGrowthDistance = maxEndD + 1.1; // leaf growth distance
```
Need `growth = progress*maxGrowthDistance`; leaves progress based on `(growth - parent.endD)/1.1`.
Need terminal branch growth reaches maxD at progress maybe maxD/(maxD+1.1) ~97%, then leaves grow last 3%. Fine.
Need if some leaves parent endD less than maxD, they appear earlier based on their path. Good.

Need compute `fit` on build and resize:
```
function computeFit() {
 let minX=0,maxX=0,minY=0,maxY=0;
 for s of segments { update bx1/by1/bx2/by2; }
 const padWorld = 0.4 maybe; minX-=0.8 etc.
 const availableW = Math.max(280, width - (isNarrow?40:420?)); // UI panel top left might overlap tree horizontally if tree centered; top margin handles panel by y. Need only reserve top 170 across full width. Use side margins 70.
 const sideMargin = Math.max(42, Math.min(110,width*0.09));
 const topMargin = height<600?105:135; // UI panel maybe 250 tall. Need tree top below 135; UI panel top-left could overlap upper left tree branches, but tree centered and panel width 350, maybe okay. Could instead reserve left 370 for tree? Not necessary; panel is transparent. But visual maybe. Use top margin 120.
 const bottomMargin = Math.max(68,height*0.1);
 const fitW = width - 2*sideMargin;
 const fitH = height - topMargin - bottomMargin;
 let sc = Math.min(fitW/(maxX-minX), fitH/(maxY-minY));
 sc = Math.min(sc*0.88, 86); // safety factor
 // Need if bboxW very small (gen1 perhaps ~2), cap 86.
 const cx = (minX+maxX)/2;
 fit.ox = width/2 - cx*sc;  // Wait map x = ox + bx*sc. To center bbox: ox + cx*sc = width/2 => ox=width/2-cx*sc.
 fit.oy = height - bottomMargin - maxY*sc; // map bottommost bbox to h-bottomMargin
 // If sc cap leads tree vertically smaller, still bottom aligned.
 fit.scale=sc;
 fit.min...
}
```
Need if maxY maybe >0 (branches below root), then root y = oy = h-bottom - maxY*sc (above bottom), fine. Need ground at root perhaps not exactly bottom. Could draw shadow at root.
Need maybe ensure `fit.oy + minY*sc >= topMargin`: since sc <= fitH/(maxY-minY)*0.88, top = h-bottom - maxY*sc + minY*sc = h-bottom -(maxY-minY)*sc >= h-bottom -0.88*fitH = topMargin+0.12*fitH. Good.
Need horizontal: width/2 center; sc <= fitW/bboxW*0.88 so edges >= sideMargin+0.06*fitW. Good.
Need cap: `sc = Math.min(90, ...)`. Need perhaps gen1 tree with height maybe 2.8 => 252px; okay. Gen1 bboxW maybe2 =>180px. Fine.
Need dynamic wind max ~30px, side margin ~100 => safe.

Need parse base coordinates and bbox. Need include leaf size in bbox maybe add pad:
```
const pad = 0.75;
minX-=pad;maxX+=pad;minY-=pad;maxY+=pad;
```
Since leaf extends at tip maybe 0.4 world units. At scale 20, 8px. `pad=0.8` gives 16px. Fine. Need wind reserve via 0.88 factor. Good.
Need maybe compute root position in fit; root at (0,0) might be centered horizontally relative bbox; okay.

Need solve:
```
function solveTree(windTime, blend) {
 const globalLean = blend * (0.020*Math.sin(windTime*0.85)+0.008*Math.sin(windTime*1.7+0.6));
 for (...) {
   const s=segments[i];
   const px = s.parent>=0 ? segments[s.parent].x2 : fit.ox;
   const py = ...
   const parentAngle = s.parent>=0 ? segments[s.parent].angle : ROOT_ANGLE+globalLean;
   const phase = s.phase;
   const wave = Math.sin(windTime*1.15 - s.depth*0.17 + phase*0.55)
      +0.35*Math.sin(windTime*2.05 - s.level*0.8 + phase*2.1);
   const flex = 0.75 + 0.10*Math.min(s.level,6) + 0.012*Math.min(s.depth,25);
   const perSegmentBend = blend * 0.0017 * wave * flex;
   const a = parentAngle + s.relAngle + perSegmentBend;
   const len = s.length*fit.scale;
   s.x1=px; s.y1=py; s.angle=a; s.x2=px+Math.cos(a)*len; s.y2=...
   s.gf=clamp((currentGrowth-s.startD)/s.length,0,1);
 }
}
```
Potential cumulative wind bend when parentAngle includes all previous local bends. Need globalLean applies only root. Good.
Need `phase` deterministic hash: `hash01(i*12.9898+generation*78.233)` maybe `Math.sin(...)*43758.5453 %1`; implement:
```
function hash01(n){ const x=Math.sin(n*12.9898+78.233)*43758.5453; return x-Math.floor(x); }
```
Need maybe `phase = hash01(i+1+generation*1000)*Math.PI*2`.
Need local bend amplitude 0.0017 * (0.75+0.6+0.3)=0.0028 max; 32 segments max cumulative0.09 rad if all same sign; plus branch depth maybe 40 ->0.11 rad. Endpoint shift maybe 30px. Fine.
Need gen1 visible lean 0.028 rad * height252 ->7px plus local 1px; maybe gentle but visible. Could increase globalLean to 0.035 +0.012 =0.047 rad; height500 ->23px, gen1->12px. Let's use `0.028*sin + 0.010*sin` max0.038 rad. Good.
Need wind tip offset sample perhaps root lean zero at windTime=0.8: sin(0.68)=0.63, second sin(1.36+0.6)=0.92 ->0.0176+0.0092=0.027 rad; height500 =>14px. At 1.8: sin1.53=1, second sin3.66=-0.5 ->0.028-0.005=0.023. At3: sin2.55=.56, second sin5.7=-.55 ->0.0157-.0055=.010. Different. At4.5: sin3.825=-.63, second sin8.25=.92? -> -0.0176+0.0092=-0.0084. Good motion. Need log tip x.

Need maybe draw background with p5 transparency. Need p5 `clear()` may use `drawingContext.clearRect`. Fine. Need set `strokeCap(ROUND)` each frame perhaps. Need `blendMode(BLEND)` default.

Need draw stars:
```
function drawBackdrop() {
 noStroke();
 for i<70:
   const x = hash01(i+11)*width;
   const y = 20 + hash01(i+901)*Math.max(80,height*0.48);
   const twinkle = 0.5+0.5*Math.sin(now*0.7+i);
   fill(180,210,235,35+50*twinkle); circle(x,y,1+...);
 // moon...
}
```
Need now variable from draw pass. Could pass `now`. Need no external assets.
Need ground/hills:
```
fill(7,18,28,190);
beginShape(); vertex(0,height); vertex(0,height*0.82);
for x... vertex(x, height*0.88 + 18*sin(x*0.006+0.8)+...);
vertex(width,height); endShape(CLOSE)
```
Careful ordering; use beginShape, vertex(0,height), vertex(0,horizon), for x, vertex..., vertex(width,height), endShape(CLOSE). Fine.
Need perhaps `fill(18,37,43,210)` second hill. Draw 2 layers. Ground shadow at root. Good.
Need maybe moon at `width-105,100`; if width small, okay. Use `min(width-80,...)`.
Need perhaps CSS background:
```
body { background: radial-gradient(circle at 75% 15%, #24435a 0, transparent 40%), linear-gradient(#081522 0%,#102a35 60%,#071018 100%); }
```
Canvas clear leaves this visible.

Need UI CSS:
```
.panel { position: fixed; top: 22px; left: 24px; z-index:10; width:min(350px,calc(100vw - 48px)); padding:18px 20px; border:1px solid rgba(...); background:rgba(7,18,27,.72); backdrop-filter: blur(10px); border-radius:18px; box-shadow...; }
```
Need `backdrop-filter` might be okay no external. Need panel fix.
Buttons:
```
.gen-button { width:38px;height:36px; ...}
.gen-button.active {...}
.regrow {...}
```
Need status pill. Grammar code uses monospace.
Need readout bottom right:
```
.readout { position:fixed; right:24px; bottom:20px; ...}
```
Could show growth bar and stats. Need perhaps not overlap tree bottom; tree root center and bottom margin ~80, readout at bottom right. Fine.
Need `#announcement` maybe hidden. Use `aria-live=polite`.
Need maybe on small width hide grammar. fine.

Need dynamic DOM updates:
```
function updateDom(metrics) {
 phaseText.textContent = progress<1 ? 'Growing' : 'Swaying in wind';
 genLabel.textContent = generation;
 metricsText.textContent = `${...} symbols · ${...} segments · ${...} attached joints`;
 bar.style.width = `${...}%`;
 const b=document.body.dataset; ...
}
```
Need perhaps update every 5 frames to reduce DOM churn. But dataset needs inspect maybe always updated; every 5 frames ~12fps okay. Use `if (frameCount%5===0)`. Need initial after setup maybe set. Could call updateDom in build with metrics zeros. Need ensure `frameCount` maybe p5 global defined. Use our own `tick++` to avoid conflict.
Need `document.body.dataset...` include everything.
Need body `data-phase`. Use `#app` maybe. Add `data-generation="4"` on body.
Need maybe `data-growth`, `data-visible-segments`, `data-attached-joints`, `data-max-joint-gap-px`, `data-wind-offset-px`, `data-wind-max-offset-px`, `data-tip-x`, `data-tip-y`, `data-symbols`, `data-segments`, `data-leaves`, `data-grammar`.
Need debug object/snapshot:
```
window.__lsystemDebug = {
 get state(){ return {...}; },
 setGeneration,
 regrow: () => restart(generation),
 finishGrowth(){ growthElapsed=GROW_SECONDS; },
 geometry(){ return segments.map(...)... } // perhaps not needed
};
```
Could use p5 keyboard shortcuts. Need perhaps snapshot includes `segments` with parent, start/end, growth fraction, leaves. Browser inspect might not access object. But console log maybe. Could maybe add hidden `<pre id="debug-json">` with JSON snapshot updated every 10 frames; browser inspect DOM could read. But perhaps too much. Body dataset enough. Need not pollute visible UI.

Need perhaps internal assertion on connections:
```
if (maxGap > 0.01) console.error(...)
```
Need no errors expected. Need perhaps count all full joints even if child not visible? "visible parent-child connections". Need count only visible child. Good.
Need maybe segment draw f>0 and parent f=1. connection check includes partial child. Need verify start equals parent end. Good.
Need wind attachment count when all segments visible: attachedJoints = segments.length-1 (except root) =843 at gen5. Need log. Great.

Need terminal leaf parent perhaps choose `tipSegment` = leaf with largest `parent.endD` or deepest depth. Need choose leaf with maximum `depth`. Build:
```
let tipLeaf = leaves.reduce((a,b)=> segments[b.parent].depth > segments[a.parent].depth ? b:a)
```
Need perhaps `tipSegmentIndex`. Compute base screen coords. Need `windOffset` in metrics. Need `maxWindOffset` update after complete. Need perhaps sample tip x at wind logs.
Need wind motion check: at each log, console log tipX/tipY and offset. Need maybe if offset values same, browser motion frames still show. Fine.

Need milestones:
```
function logGrowthMilestones(now) {
 const p=progress;
 while (nextGrowthLog <=1 && p >= nextGrowthLog) {
   console.log(`[L-system] growth ${Math.round(nextGrowthLog*100)}% ...`)
   nextGrowthLog += .25;
 }
}
```
Need at p=0.25 metrics currently computed; logs perhaps after draw computing metrics. Use `metrics` from draw. Need at p=1 exactly maybe log completion separately.
Need `if (!wasComplete && progress>=1) { completedAt=now; ...; }` Need set completedAt before compute windTime. Need maybe `windTime=0` first frame. Log complete with metrics from previous frame? Could log after solve/draw. Simpler update phase at start sets `justCompleted=true`; after compute metrics, log. Need code structure.

Pseudo draw:
```
function draw() {
 const now=performance.now()/1000;
 const dt= lastFrameTime?Math.min(.05,now-lastFrameTime):0;
 lastFrameTime=now;
 let justCompleted=false;
 if (growthElapsed < GROW_SECONDS) {
   growthElapsed=Math.min(GROW_SECONDS,growthElapsed+dt);
   if (growthElapsed>=GROW_SECONDS) { completedAt=now; justCompleted=true; }
 }
 progress=growthElapsed/GROW_SECONDS;
 currentGrowth=progress*maxGrowthDistance;
 const windTime=completedAt===null?0:now-completedAt;
 const windBlend=clamp(windTime/1.3,0,1);
 clear();
 drawBackdrop(now);
 solveTree(windTime,windBlend);
 drawGround();
 drawBranches();
 drawLeaves();
 drawGrowthFront();
 computeMetrics(windBlend);
 if (justCompleted) console.log(...);
 logGrowthMilestones();
 logWindSamples(windTime);
 updateReadout();
}
```
Need on Regrow resets `lastFrameTime=performance.now()/1000` maybe avoid dt jump; but dt clamp anyway. Need reset `completedAt=null`.
Need if debug `finishGrowth` sets growthElapsed=GROW_SECONDS but `completedAt` remains null; draw detects only inside `if(growthElapsed<GROW_SECONDS)`, so won't set completion. Need handle:
```
if (growthElapsed < GROW_SECONDS) {...}
else if (completedAt === null) { completedAt=now; justCompleted=true; }
```
So fast-forward works. Need maybe add `growthElapsed` can be set to 0 on build; no issue.
Need if `regrow` called after complete, reset.

Need `computeMetrics`:
```
let visible=0, attached=0,maxGap=0,partial=0;
for s:
 if (s.gf>0) {
  visible++;
  if (s.parent>=0) {
    const p=segments[s.parent];
    if (p.gf>=1-1e-6) {
      const gap=Math.hypot(s.x1-p.x2,s.y1-p.y2);
      maxGap=Math.max(maxGap,gap);
      if(gap<0.02) attached++; else bad...
    }
  }
  if(s.gf<1) partial++;
 }
```
Need count max gap even if p not full? Since child shouldn't grow until parent full, but perhaps due floating. Include all visible child with parent>=0; that's true. Need perhaps `attached=843`. Need use `s.x1` from parent.x2, so zero.
`tip = segments[tipSegmentIndex]; baseX=fit.ox+tip.bx2*fit.scale; baseY=...; windOffset=hypot(tip.x2-baseX,...);` Need maybe `windOffset` also includes global wind and local bends. Since base geometry no wind from relAngle; yes. Need `maxWindOffset` update after complete.
Need body dataset values.
Need perhaps `window.__treeSamples.push({t, tipX, ...})` at wind logs, with max length 20. Could be useful.
Need perhaps `window.__lsystemDebug.snapshot = () => ({...})`.
Need `data-tip-x` etc.

Need draw branches using perhaps sorted segments parse order; parent before child. Round caps. Need maybe draw dark "shadow" underlayer for all segments:
```
strokeCap(ROUND);
for s of segments {
 if f<=0 continue;
 const ex=...
 stroke(24,19,17,130); strokeWeight(s.width+1.5); line(...);
}
for s of segments {
 stroke(...); strokeWeight(s.width); line(...);
}
```
Double pass 1688 lines at gen5, fine. But dark underlay could make joints slightly seamless. Is s.width+1.5 too thick at tips (2.5px) maybe okay. Could use single pass and highlight. Simpler single pass with subtle dark outline maybe expensive but okay. Need visual quality. Let's do two passes only for segments width>3? Could draw all:
- underlay `stroke(35,24,20,170); strokeWeight(s.width+1.2)`;
- main `stroke(rgb); strokeWeight(s.width)`.
Could make branches too dark but okay. Need perhaps draw underlay for all, then main. Need ensure partial segments included. Need draw "connected" visibly. Round caps.

Need perhaps draw root flare triangle? Could draw a small base shape at root to anchor. Not required. Maybe ellipse shadow.

Need draw growth front after leaves? maybe before leaves. Fine.
Need active tips from partial segments only; at gen5 there may be dozens. Use `fill(255,225,150,180); circle(ex,ey,2+2*sin...)`.
Need perhaps all leaves fully grown only near completion; nice.

Need draw leaves:
```
function drawLeaves() {
 noStroke();
 for (const leaf of leaves) {
   const s=segments[leaf.parent]; if(!s) continue;
   const lp=clamp((currentGrowth - s.endD)/1.1,0,1);
   if(lp<=0) continue;
   const h=leaf.h;
   const size = (4.5+3*h)*leafScale*easeOut(lp);
   const angle=s.angle + (h-.5)*1.1;
   ...
 }
}
```
Need note if leaf parent still not fully grown but currentGrowth > s.endD means f>=1 by definition; good.
Need `easeOut = 1 - (1-p)^3`.
Need leafShape perhaps with `bezierVertex`; need p5 global. Need perhaps fill with alpha based on lp; no stroke.
Need `leafScale = clamp(fit.scale/22, 0.75, 1.3)`.
Need leaf color from hash:
```
const warm = hash01(leaf.id*3.17+generation);
if h <.2: fill(222,166,74,...)
else if h<.6: fill(77,158,99,...)
else fill(126,178,83,...)
```
Could use numeric lerp based on `h`:
`r=64+150*h; g=130+55*(1-h); b=70+20*(1-h)` -> from green to orange. Nice.
Need perhaps draw a cluster of two leaves at each X marker? Not necessary; 243 leaves enough. Could draw one leaf plus small bud. Fine.

Need grammar display uses arrow direct Unicode. Fine. Need maybe escape `[` no issue in HTML text. Use `code`.

Need status label:
- Growing: "Growing · trunk → tips"
- Swaying: "Grown · wind sway"
- `progress` bar width.
Need stats string: `${segments.length} segments · ${leaves.length} leaves · ${attached} connected joints`.
Need perhaps "Gen 4" label.

Need include hidden debug `<div id="debug-state" hidden>` maybe body dataset enough. Could put a `<pre id="debug-state">` with compact state text; inspect may show. Need perhaps use `aria-hidden` and CSS display:none. Browser inspect likely returns textContent even hidden? Maybe. Add:
```
<pre id="debug-state" hidden></pre>
```
Update every 10 ticks with JSON. Browser inspect might show hidden DOM? likely. Need no need.

Need perhaps label body with `data-grammar-rule-x` etc. Fine.

Need use no external requests. CSS has no @import. p5 script local. Good.

Need maybe HTML file with `<meta charset>`, viewport. Need title.

Need maybe use `defer`? p5 script plain local `<script src="p5.min.js"></script>` exact filename. Then own inline script. Use no `defer` because p5 global loaded first. Good.

Need perhaps browser runner inlines p5 script; exact tag okay.

Need write.

Need test with browser. Need inspect initial output/console. Use browser reload then inspect/screenshot. Let's call reload then maybe inspect parallel? Browser tool state likely separate; need sequential.

Initial screenshot at 2% shows tiny bud at root; tree barely visible. Need verify progressive growth after a few seconds. We can use browser motion perhaps captures frames over some duration. Need understand action outputs. Call `browser motion` likely several frames. Let's do.

Interesting motion capture jumps from frame images 62%,72%,80%,90% and console logs growth 25,50,75 due screenshot maybe time skipping. Tree looks connected, progressive. But visual tree occupies only center ~400x460 and panel top left okay. There appears very thick lower trunk with uniform width and branching at ~y566. It's clearly L-system tree. Need leaves perhaps small barely visible at 90%; after growth completed should show. Need check completed tree and wind. Use motion again maybe wind logs.

Wind motion visible subtle: frames show branches shifting maybe shape narrower/leaning; tip samples differ. Good. But tree looks more like candelabra with huge straight trunk and only two big V branches, because grammar at gen4 recursively branches from X tips; maybe okay but could be more tree-like. Need check gen5 visible and growth restart. Need maybe improve branch styling/taper: trunk has constant thick width all the way to first fork then big V branches same thickness, because subtree masses of V branches are similar and trunk width. Actually root trunk width constant because entire trunk chain segment subtree sizes all same root mass? Wait many F segments from F->FF along trunk; all have huge subtree mass so width nearly max. V branches also have large subtree mass ~half, so thick. Looks okay. But perhaps tree still clearly branching. Fine.

Need click generation 5 and inspect growth restarts. Buttons coordinates: generation 5 at x274,y121. Need browser click at those coordinates perhaps. Then inspect immediate output. Need maybe first call `browser click` then `inspect` or screenshot. Let's do click gen5.

Good restart at 1%, gen5 stat 844/243. Need let growth complete and inspect tree fits. Could use key F to fast-forward (but requirement says if growth completed during inspection sample wind; we already sampled gen4 wind. Need perhaps check gen5 whole tree visible and changed structure. Use key f then screenshot. Need maybe browser `key` action with text "f". Let's try.

Gen5 visible within canvas, different branching structure (more tips/leaves). Good. But note growth milestone at 75% visible=844/844 already! That means our growth based on path distance reveals all segments by 75% of animation, then remaining 25% only leaves grow and no branch growth. Is that acceptable "progressive growth from trunk toward branch tips"? Yes, but perhaps leaves slowly grow while tree fully visible; still progressive. But could improve growth distribution so segments continue until ~95%. Why all visible at 75%? maxGrowthDistance = maxEnd +1.1, but currentGrowth at 0.75*maxD maybe greater than all segment starts+len? This implies maxEnd maybe ~? Actually maxGrowthDistance perhaps ~? Need inspect. The path distances might be much smaller relative to maxEnd+1.1; by 75%, growth >maxEnd? Wait if maxGrowthDistance = maxEnd+1.1, 0.75* that < maxEnd if maxEnd >3.3, so some deepest segments shouldn't be full. Unless `maxEnd` is small due length taper ~? Let's estimate: main trunk path after 5 generations has 16? F->FF each generation doubles F; a single X expansion adds F etc. Longest path maybe 2^5? But branch level taper and F doubling. Could be ~? Need perhaps maxEnd ~? If maxEnd=3.2, then 0.75*(4.3)=3.225 > maxEnd. So all branches visible at 75%. Indeed total path length maybe only ~3 units! Because lengths taper by branch level 0.9^level and main trunk F doubling maybe 2 per generation but levels? Let's inspect actual maxEnd via Node parse maybe or browser debug object not accessible. We can compute with a quick Node script copying expansion/parse. But likely maxEnd around3.2. Growth 6.4 sec, branch segments fully grown by 4.8 sec, leaves from some earlier time to 6.4. Console at 50% visible68/844, 75%844/844. That's a bit abrupt: because many terminal branch start distances cluster near maxEnd? Still progressive. Could adjust LEAF_GROW_DISTANCE to e.g. 0.3 rather than1.1 so branches continue to ~90% and leaves finish in last10%; better. Why leaf growth distance 1.1 huge relative to maxEnd3.2

. Need reduce to e.g. 0.25 or 0.35. Then maxGrowthDistance = maxEnd+0.35; at 75% maybe 0.75*3.55=2.66, not all; at100% all. Need leaves appear quickly after parent end. That is better distribution. Need perhaps growth speed from trunk to tips more consistent. Also note `currentGrowth` at 100% = maxEnd+0.35; all leaves full. Good. Let's compute maxEnd maybe from initial logs via browser inspect hidden debug doesn't show. Could use node quickly parse. But we can adjust to 0.35. This would yield logs at 75% visible maybe ~? more realistic. Need perhaps at gen4 current logs 25%8, 50%34, 75%92, 100%260. With maxEnd maybe2.5, LEAF_GROW=1.1 -> maxGD3.6. At75%=2.7 > maxEnd => all segments should be visible at75%, but log said92/260 not all. Wait gen4 log at75% visible92/260. So maxEnd >2.7. For gen5 log at75% visible844/844 means maxEnd <0.75*(maxEnd+1.1) => 0.25 maxEnd <0.825 => maxEnd<3.3. Could gen5 maxEnd around3.2; gen4 maxEnd maybe >2.7, maybe3.4. Why gen5 maxEnd less than gen4? Branch level taper may compress deeper branches; F doubling might increase path lengths but level taper maybe. Could be gen5 maxEnd3.3. Gen4 maxEnd maybe3.1. Let's compute quickly. Could browser console expose `window.__lsystemDebug.snapshot()` but no eval. Maybe hidden debug JSON only selected metrics. Could add maxGrowthDistance to data set and inspect. But not necessary. Need maybe use Node to parse grammar and compute path distances. Let's do with a quick script via bash using JS maybe no Node? likely node installed. We can run node with copied logic or load index.html extract? Simpler create python script replicating grammar and parse path distances. Need perhaps not necessary. But we can calculate to tune. Let's run python.

No python. Use node.

Wait maxEnd should be 62 due F doubling, not 3.2. Why log visible844 at 75% then? That suggests growth distance mapping not as thought? Need check parse: `startD = parent ? parent.endD : 0` uses parent index state.parent. But `ends` array in Node perhaps index off? Let's inspect tree parse: `segments.push(s)` then `state.parent = s.id`. `s.id=segments.length` before push, so index fine. `ends[-1]` maybe weird but okay. maxEnd 62. At 75% of maxGrowthDistance63.1 =>47.3 <62, so not all segments should be visible. Yet console says visible844/844 at75% after pressing f? Wait key f sets `growthElapsed=GROW_SECONDS`; draw then progress jumps from perhaps 0.7 to1 in one frame. But logMilestones loops through all milestone thresholds 25,50,75,100 with final `metrics` computed at 100%, so each log shows 844/844 because of jump. Indeed the log at 75% occurs after fast-forward, so all logs show final metrics. Not an issue. Gen4 logs were natural motion. Fine. Leaf growth distance 1.1 not huge relative to 62 for gen5; for gen1 1.1 is large but okay. We don't need change. Actually branch finish fraction at gen1 64.5%, leaves finish rest; progressive growth still visible. Could reduce to0.35 for better gen1 but no need. Need perhaps check gen1 visually. Need maybe generation control from1 to5 and fit. Should click 1 and finish growth, inspect. Also test Regrow restarts. Need maybe check generation change active and restart. We did gen4->5. Need perhaps test gen1 maybe full tree visible and branching. Need check `Regrow` button. Need also maybe inspect DOM data attributes; `inspect` outputs text only. Console logs enough.

Potential issue: growth at gen5 from click had natural growth logs at 25%16,50%68, then key f jumped to completion; logs at 75/100 show844 due fast-forward. Fine. Need check gen1. Click button1 at x152,y121, then screenshot maybe initial restart. Could maybe use `key f` to finish and inspect. Need perhaps use regrow button after. Let's do click gen1 and then key f, maybe in separate calls.

Need finish gen1.

Gen1 visible, connected. Leaves tiny maybe okay. Need test Regrow button restarts growth. Click regrow at x87,y170 perhaps. Then inspect immediate. Need maybe test unchanged grammar and reset. Let's do.

Regrow works reset to0, same generation grammar. Need perhaps check console errors: none. Need maybe inspect body data attributes for wind offsets etc. Browser `inspect` maybe returns DOM text only, not attributes. Could call `browser inspect` after motion; perhaps it returns console and dom not attrs. But we have console logs and hidden debug JSON not shown. Need perhaps no need.

Need consider requirement "Bound grammar expansion and keep whole tree visible at every supported generation." We have cap100000 and dynamic fit. Need verify gen2/3 maybe tree visible. We checked gen1,4,5. Could quickly click gen3 and finish, screenshot. Need maybe no need but "every supported generation" perhaps robust fit formula guarantees. Could test gen2/3 maybe via clicks and key f, but time okay. Need maybe also check browser at smaller viewport? Browser tool fixed 1200x800. fit formula accounts resize but not tested. Unverified.

Need maybe potential issue with generation control dimensions at 1200x800: panel top-left and tree top at y200 for gen5, no overlap. Good.

Need perhaps improve visual style? Tree is a bit flat, but acceptable. Requirements prioritize function. Leaves colors tiny at gen5 but visible. Wind movement subtle; tip offsets up to12px. Need perhaps "sways gently" yes. Need perhaps ensure child branches remain attached under wind: logs maxGap0 at all wind samples. Good.

Need perhaps ensure progressive growth from trunk toward branch tips. We saw frames at 62/72/80/90 showing trunk then branches, and logs visible counts. Good.

Need maybe issue at initial screenshot: tree root with a glowing dot could be mistaken random line drawing, but later clearly tree. Fine.

Need maybe issue with "same chosen grammar" on Regrow: buildTree regenerates deterministic grammar. Good.

Need maybe issue with "generation control from 1 to 5": buttons and keyboard. Good.

Need maybe issue with "Bound grammar expansion": maxSymbols check. Need perhaps cap should be explicit and perhaps if cap reached, generation may not fully expand but remains balanced. Yes.

Need perhaps issue with "whole tree visible at every supported generation" under wind: fit uses 0.88 and padding; gen5 screenshot has wide margins. Gen1 tree fits. We can test gen3 quickly. Also maybe need check generation 2 after changing from1. We can click gen3 and finish. Need perhaps verify growth restarts with different branching structure from gen1. Click at x213

y121. Then key f. Let's do combined sequential maybe call click then key via parallel? Browser state sequential, parallel race bad. Use two calls.

Interesting root moved y from640 to690 due bbox maxY for gen3 maybe different; still ground/hills at bottom ~? root at690, fine. Need finish and screenshot.

Gen3 nice. Need perhaps check gen2 too? likely fit. Could click gen2 and finish. But perhaps enough. Need maybe maybe issue: root at y695 for gen3, tree top y220, within canvas, no clipping. Gen5 top y200. Fine.

Need perhaps check actual wind motion frames visible at gen5: console logs show tip positions change and maxGap0. Good.

Need maybe check body dataset via browser inspect? We can call `browser inspect` now maybe output includes DOM attributes? Let's see.

Inspect screenshot gen3 after wind, shape slightly changed from previous (branch tips). Good. Need perhaps no console errors. Need maybe check gen2 to be thorough. Could use keyboard `2` then `f`, but browser key text "2" will select gen2. Then key f. Let's do maybe one call with `key text=2`, then key f. Could perhaps skip because fit formula robust. But requirement "whole tree visible at every supported generation" perhaps need verify all 5. We did1,3,4,5. Gen2 likely between. Could test. Need maybe no time pressure—15 minutes maybe still okay. Let's do.

Notice generation3 button has focus outline due keyboard navigation maybe okay. Need finish gen2.

All generations visually checked. Need maybe note focus outline on gen3 when using keyboard; not a problem. Could perhaps avoid by `keyPressed` returning false? Focus ring from previous click? Actually gen3 button has outline because browser tool key '2' perhaps focus is still on gen3 button from click? The active button gen2 is gold, gen3 has white outline due focus. That's fine accessibility.

Need maybe consider hidden debug object `window.__lsystemDebug` defined only after buildTree; fine. Need no console errors. Need perhaps no syntax errors. Good.

Need perhaps refine one issue: When generation changes via key '2' while focus on button3, p5 keyPressed invokes buildTree but browser default might also activate button? No, key "2" doesn't. Fine.

Need perhaps maybe use p5 library through plain script tag exact filename; yes.

Need maybe run static check of file size and final file present. Need maybe maybe use `grep` to ensure no external URLs. Could do quick. Also need maybe ensure body data attributes update after complete. Could perhaps use a browser action `type` into some hidden field? no. Could maybe use `browser inspect` not show attributes. But hidden debug pre likely not shown because DOM text extraction ignores hidden? It did not include hidden debug. Could inspect via screenshot? Hidden. Could remove hidden attribute and put debug JSON as small text perhaps unnecessary. Need not.

Need perhaps consider browser tool's final state gen2 with growth complete; artifact when runner loads fresh will default gen4. Fine.

Need maybe add a visible or hidden data panel that can be inspected via `browser inspect`, perhaps body dataset not shown. But internal console logs are enough and requirements ask us to verify, not app to expose. We did.

Need maybe maybe test Regrow after complete with button and verify growth reset from 0. Done. Need maybe check changing generation to5 resets from 0 and different structure. Done. Need maybe check parent-child connections at growth and wind. Console max gap0. Done. Need maybe check wind motion sample. Done. Need maybe check whole tree visible all gens. Done 1-5. Good.

Need perhaps consider "bound grammar expansion" cap100000 but max generation5 only1813 symbols; explicit. Good.

Need perhaps avoid external CDN/network: no URLs except maybe none. Need check.

Need perhaps maybe no need further edits. But let's scrutinize code for potential subtle issues in final artifact runner where p5.min.js inlined. Does script execution order work? p5 script inlined before own script. Yes. Global functions setup/draw declared. `window.setup` etc. p5 global mode detects functions maybe p5 automatically instantiates on window load. Since p5.min.js is loaded synchronously before inline script, p5 registers load event; our script defines functions before load event. Fine.

Potential issue with body data attributes and `dom.debug` hidden pre; no error. `dom.debug.textContent` works. Good.

Potential issue with `window.__lsystemDebug.snapshot` being created in setup after buildTree; buildTree uses `updateReadout`, dom set. fine.

Potential issue with `fit.scale` computed using `window.innerWidth`, `window.innerHeight` rather than p5 width/height; p5 canvas uses `windowWidth/windowHeight` which likely equals those. On device with scrollbars hidden, okay.

Potential issue with `state.heading` bend introduced after each F, but turtle stack saved state at branch point; side branches and continuation start from same parent tip. However the `baseHeading` for continuation may include bend; `relAngle` computed relative to parent segment `baseHeading`. Parent segment's `baseHeading` is before its own bend, while state.heading after bend includes that bend. Thus continuation relAngle=bend. Good. But when a `[` is pushed after an F, state.heading includes bend; side branch with +angle has relAngle=bend+angle. On `]`, restore state from saved including bend; continuation after maybe F has relAngle=bend. So all good.

Potential issue with parse of `X` at final grammar expansion: X markers can be at state with parent segment; leaf attached. Good.

Potential issue with min/max base bbox perhaps minY includes pad negative and maxY pad positive. Fit.oy = h-bottom - maxY*sc; root (0,0) at h-bottom-pad*sc. This is a bit above ground; ground shadow at root. Fine. initial root at y640 for gen1 maybe because maxY0.8*90=72 => h-bottom84 -72=644. Yes. Root around644. Gen3 root y695 because maxY=0.8, scale maybe? Actually sc maybe21, maxY0.8 -> y700-17=683. Fine.

Wind global lean rotates around root; tree may move into bottom? Root fixed, branches mostly upward, slight lean can push left/right but not down. maxY perhaps from downward branches plus lean; fit margin okay. Leaves still visible. Good.

Potential issue with `clear()` and p5 canvas opaque default? p5 `clear()` makes transparent; CSS gradient visible. Screenshot confirms.

Potential issue with UI panel box on small screens: at width<680, grammar hidden; controls okay. fit top margin 132 regardless; on height<620 top105. readout may overlap tree but okay. Not verified small viewport. Can mention unverified responsive resizing.

Need perhaps maybe change initial default generation to3? User didn't specify. Gen4 default nice. Good.

Need maybe maybe add explicit `MAX_SYMBOLS` body data? not needed.

Need maybe maybe update code with no changes. Need perhaps final response concise with what checked and unverified. Should mention file path and checks. Need be honest: "I checked generations 1–5 fit/restart etc; wind samples from console; no console errors. Unverified: non-1200x800 viewport resizing, actual cap-hit branch." Need perhaps state "post-load runner inlining" not directly tested? We used p5.min.js local script; runner will inline. Could mention perhaps not tested final inlined artifact, but code uses plain local tag. Need report unverified behaviors. The addendum asks "briefly report what you actually checked and which behaviors remain unverified." Must include.

Need maybe maybe note we tested representative checks:
- initial output and console.
- growth sampled at 25/50/75/100% via motion frames/logs, visible counts and parent-child joints max gap0.
- gen changes 4->5->1->3->2; restarted at0 and different symbol/segment counts.
- Regrow reset at0.
- full tree visible all gens 1-5 at 1200x800.
- wind after completion via motion frames and tip samples, max gap0.
- no errors.
- unverified small viewport resize and cap truncation path (never hit at max gen).
Need maybe mention p5 local script. Good.

Before final, perhaps need ensure index.html present (yes). No need save further. Could maybe reload to default gen4 final state? Browser state not file. Runner will reload fresh anyway. Fine.

Need perhaps maybe think about phrase "sample branch growth and inspect visible parent-child connections" We did via screenshots and logs. Good.

Could include final answer with clear file path.

Need perhaps no need to mention visual styling details. But report concisely.

Let's formulate final with bullet lists.