sverchok-agents-code-validator

Sverchok Code Validator Agent

Systematic validation checklist for reviewing Sverchok node code. Run this checklist against any Sverchok Python code to identify errors, anti-patterns, and correctness issues. Targets Sverchok v1.4.0 on Blender 4.0+.

Quick Reference: When to Activate

Activate this validator when:

Reviewing, auditing, or validating Sverchok node scripts
Checking custom node code before deployment
Generating new Sverchok node code (run validator on output)
Investigating data corruption, silent failures, or incorrect geometry
Reviewing SNLite scripts, SN Functor B scripts, or custom node classes

Validation Checklist

Run each check in order. Each check has a severity level:

BLOCKER: Code will crash, produce data corruption, or cause silent failures
WARNING: Code has a bug, performance issue, or missing best practice
INFO: Code works but does not follow Sverchok conventions

CHECK 1: Data Nesting Correctness

Severity: BLOCKER

Verify that all sv_set() calls use the correct nesting level for their socket type.

Required nesting levels:

Socket Type	Required Level	Example
`SvVerticesSocket`	3	`[[(x,y,z), (x,y,z)]]`
`SvStringsSocket`	2	`[[1, 2, 3]]`
Edges	2	`[[(0,1), (1,2)]]`
Faces	2	`[[(0,1,2)]]`
`SvMatrixSocket`	1	`[Matrix(), Matrix()]`

Detection: Find all self.outputs[...].sv_set(...) calls. Trace the argument back to its construction. Verify the outermost list depth matches the socket type.

Flag BLOCKER if:

Vertices are output at level 2 (missing object wrapper): sv_set([(0,0,0), (1,0,0)])
Strings/edges/faces are output at level 1 (flat list): sv_set([1, 2, 3])
Matrices are output at level 2 (double-wrapped): sv_set([[Matrix()]])

CHECK 2: updateNode Callback on All Properties

Severity: BLOCKER

Every bpy.props.*Property declaration that affects node output MUST include update=updateNode.

Detection: Find all lines matching *Property( (FloatProperty, IntProperty, BoolProperty, EnumProperty, StringProperty, FloatVectorProperty, IntVectorProperty, BoolVectorProperty). Verify each contains update=updateNode.

Flag BLOCKER if: Any property lacks update=updateNode.

Exception: Properties that only control UI display (not computation) may omit updateNode. Flag INFO instead if the property name suggests UI-only use (e.g., show_options, expand_ui).

CHECK 3: Output Connection Check

Severity: WARNING

The process() method SHOULD exit early if no outputs are connected.

Detection: Check the first lines of process() for:

if not any(s.is_linked for s in self.outputs):
    return

Flag WARNING if: process() does not check output connections before performing computation. This causes unnecessary computation when no downstream node uses the output.

CHECK 4: match_long_repeat Before zip

Severity: BLOCKER

When iterating over multiple inputs with zip(), inputs MUST first be matched using match_long_repeat().

Detection: Find all zip(...) calls in process() where arguments are socket input data. Check that match_long_repeat() was called on those inputs before the zip().

Flag BLOCKER if: zip() is used on socket inputs without prior match_long_repeat(). Plain zip() silently truncates data to the shortest input.

CHECK 5: Socket Creation Only in sv_init/sv_update

Severity: BLOCKER

Socket creation (self.inputs.new(...) or self.outputs.new(...)) MUST only occur in sv_init() or sv_update().

Detection: Find all .inputs.new( and .outputs.new( calls. Verify each occurs inside sv_init or sv_update methods.

Flag BLOCKER if: Socket creation occurs inside process(). This creates a new socket on every evaluation, corrupting the node.

CHECK 6: deepcopy for Input Data

Severity: WARNING

Input data retrieved via sv_get() SHOULD NOT be mutated in-place without deepcopy=True.

Detection: Find sv_get() calls. If the returned data is subsequently modified (.append(), [i] = ..., del, .pop(), .extend(), .insert(), .sort(), .reverse()), verify that deepcopy=True was passed (or that a manual copy was made).

Flag WARNING if: Input data is mutated without deepcopy. This corrupts cached data and affects upstream nodes.

Note: sv_get(deepcopy=True) is the default in recent Sverchok versions. Flag only if deepcopy=False is explicitly set and data is mutated.

CHECK 7: Correct SNLite Aliases

Severity: BLOCKER

In SNLite header declarations, socket type aliases MUST use the correct single-letter codes.

Valid aliases:

Alias	Socket Type
`s`	`SvStringsSocket`
`v`	`SvVerticesSocket`
`m`	`SvMatrixSocket`
`o`	`SvObjectSocket`
`C`	`SvCurveSocket`
`S`	`SvSurfaceSocket`
`So`	`SvSolidSocket`
`SF`	`SvScalarFieldSocket`
`VF`	`SvVectorFieldSocket`
`D`	`SvDictionarySocket`
`FP`	`SvFilePathSocket`

Flag BLOCKER if: SNLite header uses invalid aliases such as vertices, string, matrix, float, int, vector.

CHECK 8: Node Docstring Format

Severity: INFO

Custom node classes SHOULD include a docstring with Triggers: and Tooltip: lines.

Expected format:

class SvMyNode(SverchCustomTreeNode, bpy.types.Node):
    """
    Triggers: keyword1 keyword2
    Tooltip: Short description
    """

Flag INFO if: Docstring is missing, or Triggers: / Tooltip: lines are absent. These are used by Sverchok's node search (Shift+S).

CHECK 9: Standard Process Method Pattern

Severity: WARNING

The process() method SHOULD follow the standard 5-step pattern:

Early exit if no output connected
Read inputs with sv_get(default=...)
Match input lengths with match_long_repeat()
Process each object in a loop
Set outputs with sv_set()

Flag WARNING if: process() deviates significantly (e.g., missing default values on sv_get, no list iteration, direct scalar output without wrapping).

CHECK 10: IfcSverchok Double-Nesting

Severity: BLOCKER

Data sent to IfcSverchok nodes MUST use standard Sverchok nesting (level 2 for strings).

Detection: If the node tree contains IfcSverchok nodes (bl_idname starting with SvIfc), verify that all data passed to IFC node inputs follows Sverchok nesting conventions.

Flag BLOCKER if: Single-nested data is passed to IFC nodes:

# WRONG
self.outputs['Names'].sv_set(["Wall_001"])
# CORRECT
self.outputs['Names'].sv_set([["Wall_001"]])

CHECK 11: BMesh Cleanup (bm.free())

Severity: BLOCKER

Every bmesh.new() or bmesh_from_pydata() call MUST have a corresponding bm.free() call.

Detection: Track BMesh variable assignments. Verify each has a bm.free() call after the last usage. Exception: BMesh obtained via bmesh.from_edit_mesh() must NOT be freed manually.

Flag BLOCKER if: A standalone BMesh is created without bm.free(). This leaks memory.

CHECK 12: NumPy Optimization Opportunities

Severity: INFO

Flag opportunities where Python loops over vertex/numeric data could be replaced with NumPy vectorized operations.

Detection: Find for loops that iterate over vertex lists performing element-wise arithmetic.

Flag INFO if: A loop performs operations like (v[0] * s, v[1] * s, v[2] * s) that could be (np.array(verts) * s).tolist().

CHECK 13: Import Validation

Severity: BLOCKER

Verify that all Sverchok imports are correct and available.

Required imports per pattern:

Usage	Required Import
`updateNode`	`from sverchok.data_structure import updateNode`
`match_long_repeat`	`from sverchok.data_structure import match_long_repeat`
`SverchCustomTreeNode`	`from sverchok.node_tree import SverchCustomTreeNode`
`bmesh_from_pydata`	`from sverchok.utils.sv_bmesh_utils import bmesh_from_pydata`
`pydata_from_bmesh`	`from sverchok.utils.sv_bmesh_utils import pydata_from_bmesh`
`SvNoDataError`	`from sverchok.core.sv_custom_exceptions import SvNoDataError`

Flag BLOCKER if: Code uses updateNode, match_long_repeat, or SverchCustomTreeNode without the correct import statement. Flag BLOCKER if code imports from non-existent Sverchok modules.

CHECK 14: Socket Name Consistency sv_init↔process

Severity: BLOCKER

Socket names used in sv_get() / sv_set() calls in process() MUST match the names defined in sv_init().

Detection: Extract socket names from self.inputs.new('...', 'Name') and self.outputs.new('...', 'Name') in sv_init(). Compare against self.inputs['Name'] and self.outputs['Name'] references in process().

Flag BLOCKER if: A socket name in process() does not match any socket created in sv_init(). This causes a KeyError at runtime.

CHECK 15: match_long_repeat Unpacking Pattern

Severity: WARNING

The result of match_long_repeat() MUST be unpacked correctly.

Correct pattern:

verts, scale = match_long_repeat([verts, scale])

Flag WARNING if: Result is not unpacked (assigned to single variable) or unpacking count does not match input count.

CHECK 16: sv_get Default Pattern

Severity: WARNING

sv_get() calls SHOULD provide a default parameter for optional inputs.

Detection: Find sv_get() calls without default= on non-mandatory inputs.

Flag WARNING if: An optional input uses sv_get() without a default value. This raises an exception when the socket is unconnected.

Correct pattern:

verts = self.inputs['Vertices'].sv_get(default=[[]])
scale = self.inputs['Scale'].sv_get(default=[[1.0]])

CHECK 17: Registration Completeness

Severity: BLOCKER

Custom node classes MUST define all required registration attributes.

Required attributes:

Attribute	Purpose
`bl_idname`	Unique identifier (must start with `Sv`)
`bl_label`	Display name in the node editor

Recommended attributes:

Attribute	Purpose
`sv_category`	Category for Shift+S menu
`bl_icon`	Icon identifier

Flag BLOCKER if: bl_idname or bl_label is missing. Flag INFO if sv_category or bl_icon is missing.

CHECK 18: Property Type Validation

Severity: BLOCKER

Verify that bpy.props types are used correctly in node class annotations.

Flag BLOCKER if:

FloatProperty used where IntProperty is needed (counts, indices)
CollectionProperty or PointerProperty used without proper registration
Property type annotation uses = instead of : (Blender 2.80+ requires annotation syntax)

Correct:

count: IntProperty(name='Count', default=5, update=updateNode)

Wrong:

count = IntProperty(name='Count', default=5, update=updateNode)  # Old syntax

CHECK 19: Edge/Face Data Format Validation

Severity: BLOCKER

Edge data MUST be tuples/lists of exactly 2 integers. Face data MUST be tuples/lists of 3 or more integers.

Detection: Trace edge and face data construction. Verify tuple sizes.

Flag BLOCKER if:

Edge tuples contain fewer or more than 2 elements
Face tuples contain fewer than 3 elements
Edge/face indices are floats instead of integers

Severity Summary Decision Tree

Code will crash or corrupt data?
├── YES → BLOCKER
│   ├── Wrong nesting level on sv_set() (CHECK 1)
│   ├── Missing updateNode on property (CHECK 2)
│   ├── zip() without match_long_repeat (CHECK 4)
│   ├── Socket creation in process() (CHECK 5)
│   ├── Invalid SNLite alias (CHECK 7)
│   ├── Wrong IfcSverchok nesting (CHECK 10)
│   ├── Missing bm.free() (CHECK 11)
│   ├── Missing/wrong imports (CHECK 13)
│   ├── Socket name mismatch sv_init↔process (CHECK 14)
│   ├── Missing bl_idname or bl_label (CHECK 17)
│   ├── Wrong property annotation syntax (CHECK 18)
│   └── Invalid edge/face tuple size (CHECK 19)
├── NO → Code has bug or missing best practice?
│   ├── YES → WARNING
│   │   ├── No output connection check (CHECK 3)
│   │   ├── Input mutation without deepcopy (CHECK 6)
│   │   ├── Non-standard process() pattern (CHECK 9)
│   │   ├── Wrong match_long_repeat unpacking (CHECK 15)
│   │   └── sv_get() without default (CHECK 16)
│   └── NO → Convention issue?
│       ├── YES → INFO
│       │   ├── Missing Triggers/Tooltip docstring (CHECK 8)
│       │   ├── NumPy optimization opportunity (CHECK 12)
│       │   └── Missing sv_category or bl_icon (CHECK 17)
│       └── NO → PASS

Auto-Fix Patterns

When a check fails, apply these fixes automatically where safe:

Issue	Auto-Fix
Missing object wrapper on vertices	Wrap in `[data]` → `sv_set([vertices])`
Missing object wrapper on strings	Wrap in `[data]` → `sv_set([numbers])`
Missing `updateNode`	Add `update=updateNode` to property
Missing output check	Insert early-exit block at start of `process()`
`zip()` without matching	Insert `match_long_repeat()` before `zip()`
Missing `bm.free()`	Insert `bm.free()` after last BMesh usage
Invalid SNLite alias	Replace with correct single-letter alias
Missing `default=` on `sv_get()`	Add `default=[[]]` for geometry, `default=[[0]]` for numbers
Old property syntax (`=`)	Convert to annotation syntax (`:`)
Single-nested IFC data	Wrap in extra list level
Missing import for `updateNode`	Add `from sverchok.data_structure import updateNode`
Missing import for `match_long_repeat`	Add `from sverchok.data_structure import match_long_repeat`

Validation Report Format

After running all checks, produce a report:

## Validation Report
Target: Sverchok v1.4.0
Total Issues: N

### BLOCKERS (N)
- [CHECK X] Description — file:line

### WARNINGS (N)
- [CHECK X] Description — file:line

### INFO (N)
- [CHECK X] Description — file:line

### Auto-Fixes Applied (N)
- Description — file:line

Reference Links

Validation Rules: references/methods.md
Before/After Examples: references/examples.md
Anti-Patterns Catalog: references/anti-patterns.md

Dependency Skills

sverchok-errors-common — Common Sverchok error patterns and diagnosis
sverchok-impl-custom-nodes — Custom node development patterns
sverchok-impl-ifcsverchok — IfcSverchok integration patterns

Official Documentation

Sverchok GitHub: https://github.com/nortikin/sverchok
Sverchok Documentation: https://nortikin.github.io/sverchok/
Sverchok Custom Nodes: https://github.com/nortikin/sverchok/wiki/Custom-Nodes

About this skill

Quick Reference: When to Activate

Validation Checklist

CHECK 1: Data Nesting Correctness

CHECK 2: updateNode Callback on All Properties

CHECK 3: Output Connection Check

CHECK 4: match_long_repeat Before zip

CHECK 5: Socket Creation Only in sv_init/sv_update

CHECK 6: deepcopy for Input Data

CHECK 7: Correct SNLite Aliases

CHECK 8: Node Docstring Format

CHECK 9: Standard Process Method Pattern

CHECK 10: IfcSverchok Double-Nesting

CHECK 11: BMesh Cleanup (bm.free())

CHECK 12: NumPy Optimization Opportunities

CHECK 13: Import Validation

CHECK 14: Socket Name Consistency sv_init↔process

CHECK 15: match_long_repeat Unpacking Pattern

CHECK 16: sv_get Default Pattern

CHECK 17: Registration Completeness

CHECK 18: Property Type Validation

CHECK 19: Edge/Face Data Format Validation

Severity Summary Decision Tree

Auto-Fix Patterns

Validation Report Format

Reference Links

Dependency Skills

Official Documentation