The user wants a complex fluid simulation in a single HTML file. Let me break down all the requirements:

1. A glass aquarium with a side panel that develops a crack and bursts
2. Water escaping with flow strength based on water depth (Torricelli's law)
3. A curved water jet affected by gravity
4. A spreading puddle that collides with room boundaries
5. Fish, rocks, plants, and a floating toy with different density/buoyancy/drag/current behaviors
6. Objects transitioning from underwater to airborne to floor collisions
7. Fish attempting to swim against the current before being swept through
8. Glass fragments with angular velocity, collisions, water resistance
9. Visible waterline that lowers continuously
10. User can drag crack vertically before triggering failure
11. Lower crack = stronger jet (more water pressure)

This is a very complex simulation. I'll build it using Canvas 2D. Let me design the architecture:

**Layout:**
- The aquarium is viewed from the side, taking up the left/center portion
- Water fills the tank up to a certain level
- The right panel of the tank is where the crack appears
- Outside the tank is the room floor where water spreads

**Physics:**
- Torricelli's law: v = sqrt(2*g*h) where h is depth from water surface to crack
- Flow rate: Q = A * v (area of crack * velocity)
- Water particles for the jet, affected by gravity
- Puddle spreading on the floor
- Objects (fish, rocks, plants, toy) with buoyancy, drag, and current forces
- Glass fragments with rotation, gravity, collision with floor/walls

Let me design this step by step:

**Tank dimensions (in pixels):**
- Width: 500, Height: 400
- Positioned on the canvas
- Right wall is where the crack forms
- Water fills the tank

**States:**
1. Pre-crack: User can drag a crack indicator vertically on the right wall
2. Cracked: Crack is visible, water starts leaking
3. Burst: Panel bursts, water gushes out

Actually, let me re-read: "Let the user drag the crack vertically before triggering the failure." So the user positions the crack, then triggers it. And "A lower crack should initially produce a stronger jet than a higher crack" - this follows Torricelli's law where v ∝ √h.

Let me plan the implementation:

**Canvas setup:**
- Big canvas, maybe 1000x600
- Tank on the left side
- Room floor below and to the right

**Tank:**
- x: 100, y: 80, width: 400, height: 350
- Right wall at x: 500, y: 80 to y: 430
- Glass thickness: maybe 8px

**Crack:**
- On the right wall
- User drags it vertically with mouse
- Click to trigger the burst

**Water:**
- Inside tank, initially full
- Water level decreases as water escapes
- Water particles for the jet
- Puddle on the floor

**Objects:**
- Fish (buoyant, tries to swim against current)
- Rocks (sink)
- Plants (anchored at bottom)
- Floating toy (buoyant, floats at surface)

Let me code this up. I'll use a particle-based approach for the water jet and a simplified approach for the puddle.

Actually, let me think about this more carefully. The water needs to:
1. Have a visible waterline inside the tank that lowers
2. Produce a jet that exits through the crack
3. The jet curves due to gravity (parabolic trajectory)
4. Form a puddle on the floor that spreads

For the water jet, I'll use water particles that are emitted from the crack with initial velocity based on Torricelli's law (horizontal velocity = sqrt(2*g*h_depth)), then fall under gravity.

For the puddle, I'll simulate it as a growing shape on the floor. The puddle starts at the point where the jet hits the floor and spreads outward, constrained by walls.

For the waterline, I'll track the total water volume and decrease it based on the outflow rate. The waterline height is proportional to the remaining volume.

Let me also think about the crack progression. The user drags to position, then maybe clicks or presses a key to trigger. I'll make it so:
- Drag vertically on the right wall to position the crack
- Click or press space to trigger the burst
- The crack starts small and grows

Actually, let me simplify: 
- Mouse drag on the right wall to position crack height
- Release/click to trigger the failure
- Or just have a clear UI instruction

Let me think about the structure:

```
Canvas (1000 x 650)
├── Room background
├── Tank structure (glass walls)
├── Water inside tank (blue rectangle up to waterline)
├── Objects inside tank (fish, rocks, plants, toy)
├── Crack on right wall
├── Water jet particles
├── Puddle on floor
└── Glass fragments
```

Let me code this up now. I'll use requestAnimationFrame for the game loop.

Key physics:
- Torricelli: v_out = sqrt(2 * g * h_depth)
  - h_depth = water surface y - crack y
  - This is the horizontal velocity of exiting water
- Flow rate: dV/dt = crack_width * v_out (simplified)
  - Actually more like: dV/dt = Cd * A * sqrt(2*g*h)
  - Cd ≈ 0.6 for sharp orifice
- Water volume decreases: V_new = V_old - flow_rate * dt
- Water height: h = V / (tank_width)

For the jet trajectory:
- Horizontal velocity = v_out (constant, ignoring air resistance for water)
- Vertical velocity increases due to gravity
- The jet forms a parabolic arc

For particles, I'll emit them from the crack at the calculated velocity and have them fall under gravity.

Let me think about the puddle. The puddle spreads on the floor. I'll model it as:
- The jet hits the floor at a certain x position
- Water accumulates and spreads as a thin layer
- The puddle grows as more water accumulates
- Room boundaries constrain it

For simplicity, I'll track puddle volume and spread it as a rectangle (or trapezoid) on the floor, growing as more water arrives.

OK let me now write the complete code. This is going to be quite long.

Actually, I need to be really careful about the physics to make it look good. Let me structure the code:

```javascript
// Constants
const GRAVITY = 980; // pixels/s^2
const TANK_X = 120;
const TANK_Y = 60;
const TANK_W = 380;
const TANK_H = 350;
const TANK_RIGHT = TANK_X + TANK_W;
const TANK_BOTTOM = TANK_Y + TANK_H;
const FLOOR_Y = TANK_BOTTOM + 20;
const WALL_LEFT = 0;
const WALL_RIGHT = 900;
const CRACK_WIDTH = 4; // initial crack width in px

// State
let waterVolume; // initial volume in pixel^3 equivalent
let waterHeight; // current water surface y
let crackY; // vertical position of crack
let crackOpen = false;
let crackWidth = 0;
let burstTriggered = false;
```

Let me think about units. I'll work in pixels as the base unit and scale physics accordingly.

Gravity: 980 px/s² (like 9.8 m/s² scaled)
Tank: 380 x 350 px
Initial water height: let's say 320 px (almost full)
Crack width when burst: maybe 40-60 px

Torricelli: v = sqrt(2 * g * h)
If h = 100px, g = 980 px/s², then v = sqrt(2*980*100) = sqrt(196000) ≈ 442 px/s

That seems reasonable for animation at 60fps.

Flow rate: Q = Cd * crack_width * v (per unit depth, but we're in 2D so it's per pixel depth)
In 2D, the flow is proportional to the crack width and velocity.

Actually in 2D, the volumetric flow rate (area per time) would be:
Q = crack_width * v_out

And the water loss per second = Q (in px²/s since we're in 2D)

d(waterArea)/dt = -crack_width * sqrt(2*g*h)
where h = waterSurfaceY - crackY

This is a differential equation. I'll solve it numerically each frame.

Now for the jet shape. In 2D, the water exits horizontally at v_out and then follows a parabola:
- x(t) = crackX + v_out * t
- y(t) = crackY + 0.5 * g * t²

The jet hits the floor when y(t) = FLOOR_Y.
FLOOR_Y - crackY = 0.5 * g * t²
t = sqrt(2 * (FLOOR_Y - crackY) / g)
x_impact = crackX + v_out * sqrt(2 * (FLOOR_Y - crackY) / g)

OK I think I've planned enough. Let me write the code now.

I'll structure it as:
1. Canvas setup
2. Tank and room drawing
3. Water inside tank
4. Water jet particles
5. Puddle simulation
6. Objects (fish, rocks, plants, toy)
7. Glass fragments
8. UI/interaction
9. Main loop

Let me write it all out. This will be a substantial file.

Actually, for the puddle on the floor, I need to think about room boundaries. The floor is from the tank right wall outward. The puddle should spread left and right from the impact point, constrained by:
- The tank wall on the left (can't go through)
- Some room wall on the right
- Maybe also spreading forward/back (but in 2D we just see it spreading horizontally)

I'll model the puddle as a series of points defining its surface, or more simply as a rectangle that grows.

Actually, let me make it a bit more sophisticated. The puddle starts at the impact point and spreads. I can model it as:
- leftEdge: starts at impact X, moves left until hitting tank wall
- rightEdge: starts at impact X, moves right until hitting room wall
- waterDepth: increases as more water accumulates

The puddle spread rate depends on the water depth (thin layer, shallow water equations simplified). Deeper puddle spreads faster.

But for simplicity, I'll just track the puddle volume and spread it evenly across the available floor area, constrained by walls.

Let me simplify: the puddle is a trapezoid/triangle shape on the floor. Its area equals the volume of water that has escaped. Its spread is constrained by the tank wall on the left and room wall on the right. The shape follows the floor contour.

Actually, even simpler: I'll track the puddle as a growing line on the floor. The water volume that hits the floor adds to the puddle. The puddle spreads as a thin layer. I'll render it as a thin blue shape on the floor that grows.

Let me now actually write the code. I'll focus on making it visually impressive and physically reasonable.

Here's my plan for the code structure:

```
HTML:
- Canvas element
- Instructions overlay

JS:
- Constants and configuration
- State management
- Tank rendering (glass walls with reflections)
- Water inside tank (with surface ripples)
- Crack rendering
- Water jet (particle system)
- Puddle on floor
- Objects:
  - Fish (2-3): buoyant, swim against current
  - Rocks (2-3): sink to bottom
  - Plants (2): anchored at bottom, sway
  - Floating toy: stays at surface
- Glass fragments (when burst happens)
- Mouse interaction for crack dragging
- Main update loop
- Rendering
```

OK, I'm going to write this now. It'll be long but comprehensive.

Let me think about the fish AI. The fish should:
1. When underwater, swim around normally
2. When crack opens, detect the current and try to swim against it
3. If the current is too strong, get swept toward the crack
4. If they go through the crack, become airborne and fall to the floor
5. Once on the floor, flop around

For buoyancy:
- Fish: slightly buoyant (float upward slowly when not swimming)
- Rocks: negative buoyancy (sink)
- Plants: anchored at base, stems sway
- Toy: positive buoyancy (float at surface)

For drag: objects moving through water experience drag proportional to velocity².

For current: water moving toward the crack creates a velocity field. Objects in the water are pushed toward the crack with a force that increases as they get closer to the crack (since the flow converges).

Actually, I should model the current field inside the tank. The water is all moving toward the crack. The velocity at any point depends on the flow rate and the distance from the crack. Near the crack, velocity is highest. Far from the crack, velocity is lower.

For a 2D sink flow: v(r) = Q / (2πr) where r is distance from the crack. But since the crack is on the wall, it's more like a sink on a boundary.

Simplified: I'll compute the velocity at each object's position as:
- Direction: toward the crack
- Magnitude: Q / (distance * some_factor), capped

This creates a current field that objects respond to.

Alright, let me write the code now. I'll try to keep it organized but it will be long.

One more thing: for the crack dragging, I'll make it so:
- Before bursting, the user sees a faint crack line on the right wall
- They can drag it up and down
- When they click a "BURST" button or press space, the crack opens
- The crack then widens over ~1 second to full width

Or even simpler: the user drags the crack position, and when they release at a low position, it bursts. Actually let me just do:
- Mouse over right wall area shows a crack line that follows the mouse
- Clicking sets the crack position and triggers the burst
- Or: drag to position, then click a button

I'll go with: the user sees a highlighted zone on the right wall. They click and drag to set crack position. When they release the mouse, the crack appears and starts leaking. After a short delay, it bursts fully.

Actually, let me re-read: "Let the user drag the crack vertically before triggering the failure."

So: drag to position the crack, then some action triggers the failure. I'll make it so dragging positions it, and clicking a "TRIGGER" button or pressing space causes the burst.

Let me also add a reset button.

Now, the glass fragments. When the tank bursts:
- Several glass shards fly outward from the crack area
- Each has position, velocity, angular velocity
- They experience gravity and air resistance
- They collide with the floor and walls
- Some may fall into the puddle (water resistance)

OK I think I've planned enough. Let me write the complete code.

I need to be careful about one thing: the crack width should expand over time when triggered. It doesn't instantly become fully open. This gives a nice visual progression.

Timeline:
1. t=0: User positions crack, clicks trigger
2. t=0 to t=0.5s: Crack widens from 0 to full width (say 50px)
3. t=0 to t=end: Water jets out, waterline drops
4. t=0.5s: Glass fragments fly out
5. t=0 to t=end: Puddle grows on floor
6. Objects react to current throughout

Let me now write the complete HTML file.

For the water inside the tank, I need to handle the decreasing water level. The water surface drops as water escapes. I'll compute this from the volume.

Water volume (2D area) initially: tank_width * initial_water_height
Flow rate: crack_width * sqrt(2 * g * (water_surface_y - crack_y))

Wait, but the crack is on the side wall. When the water level drops below the crack, flow stops. Actually no - the crack is a vertical line on the wall. Water flows through the portion of the crack that's below the waterline. If the crack extends from crackY to crackY+crackHeight, and water is at waterSurfaceY, then the effective crack height underwater is min(crackY+crackHeight, waterSurfaceY) - crackY. But for simplicity, I'll treat the crack as a point at crackY and only flow if waterSurfaceY > crackY.

Actually, for a more realistic crack that opens up, the crack would be a vertical gap. Water would flow through the entire submerged portion of the crack. The flow rate would integrate over the depth. But this is complex.

Simplification: treat the crack as a point opening at crackY. Flow occurs when water surface is above crackY. The flow velocity is sqrt(2*g*(waterSurfaceY - crackY)). The effective opening width is the crack width (which grows when triggered).

This gives us: lower crack = larger h = faster initial jet. ✓

OK now truly writing the code.

Let me also think about the water jet rendering. I'll use particles:
- Emit particles from the crack position
- Each particle has initial horizontal velocity = v_out (from Torricelli)
- Initial vertical velocity = 0
- Under gravity, they follow parabolic arcs
- I'll render many small blue circles/ellipses that fade out

The emission rate should be proportional to the flow rate. More flow = more particles.

For the jet visual, I can also draw a translucent blue shape following the parabolic trajectory and thickening near the impact point (like a real water jet).

Better approach: draw the jet as a series of connected line segments or a filled shape, PLUS particles for spray/droplets.

Actually, for a nice visual, I'll:
1. Draw the main jet as a semi-transparent blue shape
2. Add particle spray around it
3. The jet thins as it accelerates (continuity: area * velocity = constant)

For the jet shape, I'll compute the parabolic path from crack to floor and draw it with varying thickness. The thickness at any point is inversely proportional to the velocity at that point (continuity equation).

Velocity at point along the jet: v = sqrt(v_out² + 2*g*(y - crackY))
Thickness: thickness_at_crack * v_out / v

This gives a nice thinning effect as the water falls and accelerates.

Then at the floor, the water splashes and forms the puddle.

OK here's my final plan. I'll write it all in one go.

Let me also make the tank visually appealing:
- Glass walls with slight blue tint and reflections
- Rounded corners
- Water with slight blue transparency
- Bubbles
- Caustic-like effects (simplified)

Alright, I need to actually write this. Let me produce the complete code now. It'll be substantial.

I'll organize the JS as follows:

```
1. DOM/Canvas setup
2. Configuration
3. State
4. Tank/room geometry
5. Particle class (water droplets)
6. GlassFragment class
7. Fish class
8. Rock class
9. Plant class
10. Toy class (floating)
11. Puddle model
12. Water jet model
13. Crack model
14. Input handling
15. Update functions
16. Render functions
17. Main loop
18. Initialization
```

Let me write this now. I'll aim for ~800-1000 lines of well-structured code.

Actually, I realize I need to keep track of a lot of particles and objects. Let me be efficient with memory.

For water particles, I'll limit to ~200 max, recycling old ones.
For the puddle, I'll track total escaped volume and spread.

Let me start coding:

One thing about the fish swimming against the current - I need to model their behavior:
- Each fish has a target position they want to be at
- They swim toward their target
- The current pushes them toward the crack
- If the current force exceeds their swimming force, they get pulled toward the crack
- If they go through the crack, they're "airborne" and fall

OK I'll now write the complete HTML. Let me go for it.

I need to be careful about coordinate systems. The tank:
- Left wall: TANK_X
- Right wall: TANK_X + TANK_W
- Bottom: TANK_Y + TANK_H
- Top: TANK_Y
- The crack is on the right wall (inside face)

Water flows from inside the tank, through the crack in the right wall, out to the right side.

The floor outside is at FLOOR_Y which is a bit below the tank bottom (or at the same level). The puddle forms on the floor to the right of the tank.

Let me set:
- TANK_X = 100
- TANK_Y = 60
- TANK_W = 400
- TANK_H = 350
- TANK_RIGHT = 500
- TANK_BOTTOM = 410
- FLOOR_Y = 430 (slightly below tank for drainage realism)
- Room right wall: 900

Actually, for the floor, let me have it at the same level as the tank bottom. The tank sits on the floor. The water jets out and lands on the floor to the right.

FLOOR_Y = TANK_BOTTOM = 410.

But wait, the crack could be at various heights. The higher the crack, the further the water has to fall, and the further right it lands. The lower the crack, the more horizontal velocity (more pressure) but less distance to fall, so it might hit closer.

Let me think about this... 

With Torricelli: v_out = sqrt(2*g*h)
Time to fall: t = sqrt(2*(FLOOR_Y - crackY)/g)
Horizontal distance: d = v_out * t = sqrt(2*g*h) * sqrt(2*(FLOOR_Y - crackY)/g) = 2 * sqrt(h * (FLOOR_Y - crackY))

Where h = waterSurfaceY - crackY (depth below surface).

Interesting. So for a crack at the very bottom (large h, small floor_distance), d = 2*sqrt(large * small).
For a crack in the middle, both h and floor_distance are moderate, d = 2*sqrt(moderate * moderate) = 2*moderate.

So the maximum horizontal reach would be when h = floor_distance, i.e., crack is halfway between surface and floor. This makes sense - it's like the maximum range of a projectile.

Anyway, the jet will curve differently based on crack height. A lower crack produces a faster, more horizontal jet that reaches further before hitting the floor.

OK NOW I'm truly going to write the code. No more planning.

One concern: the water jet particles need to look good. I'll use a mix of:
1. A semi-transparent parabolic shape for the main jet
2. Small particles for spray and droplets

The main jet shape I'll draw using canvas paths.

For the puddle, I'll track the cumulative water volume that has escaped and render it as a growing blue area on the floor. I'll model it as spreading from the impact point.

Let me also add some nice touches:
- Water surface with slight wave animation
- Bubbles in the tank
- Glass reflections
- Sound indicators (visual "SPLASH" effects)

Alright, writing the code now. For real this time.

Let me think about the structure once more and then just write it. The key classes:

**WaterParticle**: x, y, vx, vy, life, size, alpha
**GlassFragment**: x, y, vx, vy, angle, angularVel, size, life
**Fish**: x, y, vx, vy, size, color, targetX, targetY, state (swimming, struggling, swept, airborne, floored)
**Rock**: x, y, vx, vy, size
**Plant**: baseX, baseY, segments, sway
**FloatingToy**: x, y, vx, vy, size

State machine for fish:
- NORMAL: swimming around randomly in the tank
- STRUGGLING: trying to swim against current, may or may not succeed
- SWEPT: being pulled toward crack
- AIRBORNE: exited through crack, falling through air
- FLOORED: on the floor, flopping

For the crack:
- crackY: vertical position (user-draggable)
- crackWidth: current width (0 initially, grows when triggered)
- crackMaxWidth: full width after opening
- crackOpen: boolean

For the burst trigger:
- User positions crack by dragging
- User clicks "BURST" button or presses space
- Crack opens over ~0.5 seconds
- Glass fragments spawn when crack reaches ~80% of max width

Water volume tracking:
- initialWaterArea = TANK_W * initialWaterHeight
- currentWaterArea decreases by flowRate * dt
- waterSurfaceY = TANK_BOTTOM - currentWaterArea / TANK_W

Flow rate:
- if waterSurfaceY > crackY: flowRate = crackWidth * sqrt(2 * GRAVITY * (waterSurfaceY - crackY))
- else: flowRate = 0

The flow rate is in px²/s (area per second in 2D).

Puddle:
- totalEscapedWater += flowRate * dt
- Puddle spreads on floor
- I'll model it as a thin layer with height proportional to volume / spread_area

For the puddle shape, I'll track the left and right edges as they spread from the impact point. The impact point is where the jet hits the floor.

Impact X = TANK_RIGHT + v_out * sqrt(2*(FLOOR_Y - crackY)/GRAVITY)

The puddle spreads from this point. I'll track puddleLeft and puddleRight which move outward at a speed proportional to sqrt(puddleDepth). This is the shallow water wave speed.

Puddle depth = totalEscapedWater / (puddleRight - puddleLeft) (assuming uniform depth)

The spread rate: d(edge)/dt ∝ sqrt(g * depth)

This creates a realistic spreading behavior. The puddle spreads fast initially (when depth is greater) and slows as it thins out.

Constraints:
- puddleLeft >= TANK_RIGHT (can't go through tank wall)
- puddleRight <= ROOM_RIGHT_WALL
- If puddleLeft hits tank wall, water starts accumulating there (depth increases)
- Same for right wall

Alright, NOW THE CODE.

I think I should focus on getting a working simulation that looks good. Let me prioritize:
1. Visual quality of water and tank
2. Correct physics for the jet and waterline
3. Good object behavior
4. Glass fragments
5. Smooth interaction

Let me write it out. I expect ~600-800 lines.

One thing: for the water jet rendering, I'll draw it as a filled shape that follows the parabolic path. I'll compute several points along the parabola and draw a polygon with varying width.

For each point along the path (parameterized by t from 0 to t_impact):
- x(t) = TANK_RIGHT + v_out * t
- y(t) = crackY + 0.5 * GRAVITY * t²
- velocity(t) = sqrt(v_out² + (GRAVITY*t)²)
- width(t) = crackWidth * v_out / velocity(t)  (continuity)

Then I'll create a filled shape by offsetting points perpendicular to the path by width(t)/2 on each side.

This gives a physically-plausible jet shape that thins as it accelerates downward.

At the impact point, I'll add splash effects (upward-spraying particles).

OK let me write this now. For real. No more changes to the plan.

Hmm, one more thing: I need the crack to be a visible breach in the glass. When it "bursts", the glass breaks and fragments fly out. Before bursting, during the "dragging" phase, maybe there's a subtle crack line visible. After triggering, the crack widens and glass pieces break away.

For the glass rendering, I'll draw the tank walls with a glass-like appearance (light blue borders with white highlights). The right wall will show the crack as a dark jagged line that widens.

Glass fragments: when the burst happens, I'll create ~8-15 triangular/rectangular glass shards that fly out from the crack area. They'll have:
- Initial position: around the crack
- Initial velocity: outward and slightly random
- Angular velocity: random spin
- Gravity pulls them down
- They collide with floor and walls
- Some may land in the puddle

When fragments hit the floor, they can bounce with reduced energy. When in the puddle, they experience water resistance.

Alright. Now I'll write the complete file. I'll aim for quality and completeness.

Let me also think about colors:
- Tank glass: light blue with white highlights, rgba(180, 210, 230, 0.5)
- Water: rgba(30, 100, 200, 0.6) - blue, semi-transparent
- Water surface: lighter blue line with slight animation
- Floor: light gray/brown
- Room walls: light beige
- Fish: orange/gold
- Rocks: dark gray
- Plants: green
- Toy: yellow rubber duck
- Glass fragments: light blue, semi-transparent
- Crack: dark line with some branching

OK let me write the code. This is going to be a major effort.

Actually, I realize I need to carefully handle the crack positioning. The crack is on the right wall of the tank. The user drags vertically. The crack Y coordinate ranges from TANK_Y + 20 to TANK_BOTTOM - 20 (some margin from top and bottom).

For the mouse interaction:
- I'll track mouse position
- If mouse is near the right wall (within 20px) and within the tank height range, show a crack preview
- Click and drag to position
- Release sets the position
- Then click "BURST" or press space to trigger

I'll add a visible UI element (a button or text) that says "Position crack by dragging, then press SPACE to trigger".

Now, truly writing the code. Here goes:

Actually, I want to also handle the case where objects (fish, rocks) go through the crack. When they exit the tank:
- They're no longer buoyant (no water to support them)
- Gravity takes over
- They fall to the floor
- They may bounce
- Fish flop around on the floor

For plants, they're anchored at the base. If the water level drops below their top, they might droop. If the current is strong, they bend toward the crack. They won't go through the crack since they're anchored.

For the floating toy, it stays at the water surface. As the water level drops, the toy goes down with it. If the water level drops below the crack, the toy might get stuck or go through if it's near the crack.

OK now writing the code. I'll focus on making it work and look good.

Here's a key consideration: I need to manage the transition when the crack first opens. The water doesn't instantly start flowing at full rate. The crack widens over time, so the flow starts small and increases.

I'll model the crack width as:
- Before trigger: width = 0 (or very thin, just visible)
- After trigger: width ramps up to maxWidth over ~0.5-0.8 seconds
- Maybe with some oscillation/shaking effect

For the glass fragments, they spawn when the crack width reaches ~70% of max.

Alright, HERE IS THE CODE:

I need to also think about what "triggering the failure" means mechanically. The user drags the crack position first, then triggers. When triggered:
1. The crack starts widening
2. Water starts jetting out
3. Glass fragments fly
4. The crack continues to widen (maybe the whole panel fails)

For dramatic effect, maybe the crack propagates upward and downward from the initial point, creating a larger breach. This would look more realistic - a crack that starts at one point and spreads.

Hmm, that adds complexity. Let me have the crack be a fixed-width opening that appears at the positioned height. The glass around it breaks away, leaving a gap.

OK, truly final plan and then I'll write it. The crack is a gap in the right wall of the tank, centered at the user-positioned Y coordinate. When triggered, this gap opens from 0 to about 50-60px wide. Water jets out through this gap.

Now writing the code:

I'll make the canvas 1000x600 for a good view. The tank on the left, room on the right.

Let me also handle the edge case where the water level drops below the crack - then the flow stops and the jet disappears. The puddle remains on the floor.

Also, objects that haven't been swept out yet remain in the remaining water. Fish that are still in the tank continue swimming in the reduced water.

Alright, here we go. I'll write the complete file now.

Let me verify the file was written correctly and check for any issues. Let me also test it conceptually to make sure all the requirements are met:

1. ✅ Water escaping through the opening with flow strength based on water depth (Torricelli's law: v = sqrt(2*g*h))
2. ✅ Curved water jet affected by gravity (parabolic trajectory)
3. ✅ Spreading puddle that collides with room boundaries
4. ✅ Fish, rocks, plants, and a floating toy reacting differently
5. ✅ Objects transitioning from underwater to airborne to floor collisions
6. ✅ Fish attempting to swim against current before being swept through
7. ✅ Glass fragments with angular velocity, collisions, water resistance
8. ✅ Visible waterline that lowers continuously
9. ✅ User drags crack vertically before triggering failure
10. ✅ Lower crack = stronger jet

Let me review the code for potential bugs:

1. The water jet shape computation uses dy = GRAVITY * t for the perpendicular, but the path is (x(t), y(t)) where x(t) = TANK_RIGHT + vOut * t and y(t) = crackY + 0.5 * GRAVITY * t². The tangent vector is (vOut, GRAVITY * t), and the perpendicular is (-GRAVITY * t, vOut) normalized. This looks correct: dx = vOut, dy = GRAVITY * t, px = -dy/len, py = dx/len. ✓

2. The water volume tracking: waterArea decreases based on flow rate. The water surface Y is computed as TANK_BOTTOM - waterArea / TANK_W. This correctly simulates the decreasing water level. ✓

3. Puddle spreading uses shallow water wave speed sqrt(g*depth). ✓

4. Fish states: swimming → struggling → swept → airborne → floored. The transition logic looks correct. ✓

5. Glass fragments spawn when crack reaches 70% of max width. They have angular velocity, gravity, air drag, floor collisions, and water resistance (in puddle). ✓

6. The crack position is draggable and affects the jet strength. ✓

One thing I notice: in `getWaterCurrent`, I'm using the same flow rate calculation. The current strength increases as the flow rate increases and decreases with distance from the crack. This creates a sink-like flow field that objects respond to. ✓

Let me also verify there are no obvious JS errors:
- `clamp` is defined ✓
- All classes are instantiated correctly ✓
- The main loop checks dt validity ✓

I think the simulation is solid. Let me also make sure the floating toy transitions correctly - it floats at the water surface, and as the water level drops, it follows. If it reaches the crack, it can get swept out. ✓

The file is complete. Let me verify it's valid by reading it back.

The file is 1543 lines and well-structured. Let me verify it's syntactically valid by checking for any obvious issues. Let me also check that the closing tags are correct.

The file looks good. Let me provide a summary to the user.