fork

name	fork
description	Save the current shader + knob state as a new numbered iteration. Usage: `/fork` (auto-detects shader) or `/fork <shader-path>`
allowed-tools	Bash Read Write Edit Grep Glob Agent mcp__claude-in-chrome__tabs_context_mcp mcp__claude-in-chrome__javascript_tool

Fork — Save Current State as New Shader Iteration

Capture the current shader code + knob values from the browser and create a new numbered .frag file with the knob values baked into comments and a companion .md doc.

Context

Arguments (optional shader path): !echo "$ARGUMENTS"

Browser tabs: !echo "Use tabs_context_mcp + javascript_tool to read current state"

Steps

1. Find the current shader

If $ARGUMENTS specifies a path, use it. Otherwise:

1. Check the browser — read window.location.search for ?shader=
2. Fall back to most recently modified .frag in the worktree

2. Read the current state from the browser

On the jam/editor tab, run:

JSON.stringify({
  shader: new URLSearchParams(window.location.search).get('shader'),
  controller: new URLSearchParams(window.location.search).get('controller'),
  knobs: Object.fromEntries(
    Object.entries(window.cranes.manualFeatures || {})
      .filter(([k]) => /^knob_\d+$/.test(k))
      .filter(([_, v]) => v !== undefined && v !== null)
      .sort(([a],[b]) => parseInt(a.split('_')[1]) - parseInt(b.split('_')[1]))
  )
})

3. Determine the new filename

Look at existing numbered files in the shader directory:

shaders/<path>/the-coat-2.frag
shaders/<path>/the-coat-3.frag
→ next: the-coat-4.frag

If no numbered files exist, use 2.frag as the first fork.

4. Copy the shader

Copy the current .frag to the new filename. Update any internal comments that reference the old name.

5. Write the companion doc

Create <new-name>.md with:

• Origin: which shader it was forked from, when, what music was playing
• Baked knob values table (knob, value, what it controls)
• Preset URL with all knob params
• Controller info if one was active
• Any notes about why this fork was created

6. Hot-swap to the new shader

Update the browser to use the new shader without reloading:

// Fetch new shader and swap
const r = await fetch('/shaders/<path>/<new>.frag?t=' + Date.now())
window.cranes.shader = await r.text()
// Update URL
const url = new URL(window.location)
url.searchParams.set('shader', '<new-shader-path>')
history.replaceState({}, '', url)

7. Report

Tell the user:

Forked old-name → new-name with knob values baked in. [list key knob settings]

Safety

• Never overwrite an existing file — always create new numbered iterations
• Confirm the shader directory exists before writing
• The fork preserves all code — it's a copy, not a diff