FIX pickerfun Python callback

[kroq-gar78]

This restores the old jQuery mechanism from 77a24b5 . I don't know what the pros/cons are of this versus the notify mechanism from legacy (3595800).

Fixes #598 .

[Copilot]

Pull request overview

This PR restores a jQuery-based surface-pick callback path so that pickerfun provided to cortex.webgl.show(...) is invoked from Python when the user clicks on the surface in the WebGL viewer (fixing #598).

Changes:

• Update the /picker Tornado handler to accept voxel coordinates as x,y,z plus vertex and hemi, and call pickerfun(voxel, vertex, hemi).
• Add a default PickPosition.prototype.callback implementation that triggers a GET to /picker on each pick.
• Update show()’s pickerfun docstring / default callback behavior.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
cortex/webgl/view.py	Updates picker callback contract and server-side /picker argument parsing/callback invocation.
cortex/webgl/resources/js/facepick.js	Restores a jQuery $.get("/picker?...") request on picks by defining a default callback.

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[Copilot]

Parsing voxel assumes a comma-separated string of exactly 3 integers; if the query param is malformed (wrong length, whitespace, non-integer), this will currently throw and return a 500. Consider validating the split length and catching ValueError to return a 400 (or ignore the pick) so a bad request can’t crash the handler.

Suggested change

	voxel: tuple[int, int, int] = tuple(int(i) for i in self.get_argument("voxel").split(","))
	vertex: int = int(self.get_argument("vertex"))
	voxel_arg = self.get_argument("voxel", None)
	if voxel_arg is None:
	self.set_status(400)
	self.finish("Missing 'voxel' query parameter")
	return
	parts = voxel_arg.split(",")
	if len(parts) != 3:
	self.set_status(400)
	self.finish("Invalid 'voxel' query parameter: expected 3 comma-separated integers")
	return
	try:
	voxel: tuple[int, int, int] = tuple(int(i) for i in parts)
	vertex: int = int(self.get_argument("vertex"))
	except (TypeError, ValueError):
	self.set_status(400)
	self.finish("Invalid 'voxel' or 'vertex' query parameter")
	return

[Copilot]

This changes the pickerfun callback contract from 2 args to 3 args. Any existing user code that defines pickerfun(voxel, vertex) will now raise TypeError when a pick occurs. To avoid a breaking change, consider supporting both signatures (e.g., attempt the 3-arg call and fall back to 2 args) and/or deprecate the old signature first.

[Copilot]

Defining callback on the prototype makes this.callback !== undefined always true, so every pick will now trigger a GET to /picker. This is a behavior change for static exports (python_interface=False) or any deployment without a /picker route, where clicks will start generating failing network requests (and potentially CORS/console noise). Consider only installing/enabling this callback when the Python picker endpoint is actually available (e.g., when running in python_interface mode, or when a callback was explicitly provided).

[Copilot]

voxel: tuple[int, int, int] uses PEP 585 built-in generics, which are not supported on Python 3.8. The repo's CI matrix includes Python 3.8, so this will raise a TypeError: 'type' object is not subscriptable at import/runtime. Use typing.Tuple[int, int, int] (or drop the annotation) to keep 3.8 compatibility.