IfcOpenShell Code Validator Agent

Quick Reference

When to Activate This Validator

Activate this validation checklist when:

• Reviewing IfcOpenShell Python code for correctness
• Auditing IFC file manipulation scripts before production use
• Checking code that creates, modifies, or reads IFC files
• Validating code that processes IFC geometry
• Reviewing code that handles multiple IFC schema versions
• Assessing performance of scripts processing large IFC files (100MB+)

Severity Levels

Severity	Meaning	Action
BLOCKER	Code will crash, corrupt data, or produce invalid IFC files	MUST fix before code is accepted
WARNING	Code has potential bugs, performance issues, or fragile patterns	SHOULD fix; document reason if deferred
INFO	Code works but does not follow best practices	MAY fix; note for future improvement

---

Validation Checklist

Execute these checks in order. Each check references the dependency skill that defines the rule.

Step 1: Schema Awareness (BLOCKER)

Source: ifcos-errors-schema

Code uses IFC entities?
├── Does code check model.schema before using schema-specific entities?
│   ├── NO → BLOCKER: Add schema check
│   └── YES → Pass
│
├── Does code use any *StandardCase entity (IfcWallStandardCase, etc.)?
│   ├── YES + no IFC4X3 guard → BLOCKER: StandardCase removed in IFC4X3
│   └── NO or guarded → Pass
│
├── Does code use IfcBuiltElement or IfcBuildingElement?
│   ├── YES + no schema branch → BLOCKER: Name differs by schema
│   └── Handled → Pass
│
├── Does code use IfcDoorStyle/IfcWindowStyle?
│   ├── YES + targets IFC4+ → BLOCKER: Use IfcDoorType/IfcWindowType
│   └── Handled → Pass
│
├── Does code use IFC4X3-only entities (IfcRoad, IfcBridge, IfcAlignment)?
│   ├── YES + schema != "IFC4X3" → BLOCKER: Entity does not exist
│   └── Correct schema → Pass
│
└── Does code access PredefinedType on IFC2X3 entities?
    ├── YES + no hasattr guard → BLOCKER: Most IFC2X3 entities lack PredefinedType
    └── Guarded → Pass

Step 2: API Usage Correctness (BLOCKER)

Source: ifcos-syntax-api, ifcos-errors-patterns

Code creates or modifies IFC entities?
├── Uses model.create_entity() for production code?
│   └── BLOCKER: Use ifcopenshell.api.run("root.create_entity", ...) instead
│
├── Uses ifcopenshell.api.run() or direct module calls?
│   ├── Invents non-existent API modules/functions?
│   │   └── BLOCKER: Verify against the 35 API modules table
│   ├── Uses positional arguments after model?
│   │   └── BLOCKER: ALWAYS use keyword arguments
│   └── Passes single element where list is required (v0.8+)?
│       └── BLOCKER: products=, related_objects= require lists
│
├── Modifies entity attributes directly (wall.Name = "X")?
│   ├── For Name/Description → WARNING: Use api.run("attribute.edit_attributes", ...)
│   └── For relationships (ContainedInStructure, IsTypedBy) → BLOCKER: Use API
│
├── Creates relationships manually (model.create_entity("IfcRelContained..."))?
│   └── BLOCKER: Use spatial.assign_container, aggregate.assign_object, etc.
│
└── Creates IFC file with ifcopenshell.file() for production use?
    └── WARNING: Use ifcopenshell.api.run("project.create_file", ...) instead

Step 3: File I/O Correctness (BLOCKER/WARNING)

Source: ifcos-syntax-fileio

Code opens or creates IFC files?
├── Uses ifcopenshell.file() without explicit schema= parameter?
│   └── WARNING: ALWAYS specify schema explicitly
│
├── Uses project.create_file() with schema= instead of version=?
│   └── BLOCKER: Parameter name is version=, not schema=
│
├── Creates file without IfcProject + units + context + spatial hierarchy?
│   └── WARNING: Incomplete IFC files cause downstream failures
│
├── Calls model.remove() directly on products?
│   └── BLOCKER: Use api.run("root.remove_product", ...) for safe removal
│
├── Uses transactions?
│   ├── Missing end_transaction() or discard_transaction()?
│   │   └── BLOCKER: Open transactions cause undefined behavior
│   └── Calls undo()/redo() inside active transaction?
│       └── BLOCKER: NEVER call undo/redo during active transaction
│
└── Writes to disk?
    └── Pass (model.write() is safe)

Step 4: Entity Reference Safety (BLOCKER)

Source: ifcos-errors-patterns

Code removes entities or uses undo?
├── Accesses entity attributes after model.remove()?
│   └── BLOCKER: Entity wrapper is invalid after removal
│
├── Iterates and removes simultaneously?
│   └── BLOCKER: Collect to list first, then remove
│
├── Caches entity references across file modifications?
│   └── BLOCKER: References invalidate after remove/undo
│
└── Extracts data before removal?
    └── Pass

Step 5: None Return Value Handling (BLOCKER)

Source: ifcos-errors-patterns

Code calls utility functions that return None?
├── Uses get_container(element).Name without None check?
│   └── BLOCKER: get_container returns None if no containment
│
├── Uses get_type(element).Name without None check?
│   └── BLOCKER: get_type returns None if no type assigned
│
├── Uses get_material(element) without None check?
│   └── BLOCKER: get_material returns None if no material
│
├── Uses geom.create_shape() without try/except RuntimeError?
│   └── BLOCKER: Geometry processing fails for many elements
│
└── Uses model.by_guid() without None check?
    └── WARNING: Returns None if GUID not found

Step 6: GUID Handling (BLOCKER)

Source: ifcos-errors-patterns

Code creates entities with GlobalId?
├── Uses uuid.uuid4() or str(uuid) for GlobalId?
│   └── BLOCKER: IFC requires 22-char base64 GUID; use ifcopenshell.guid.new()
│
├── Reuses same GUID for multiple entities?
│   └── BLOCKER: Every entity MUST have a unique GlobalId
│
└── Uses ifcopenshell.api.run("root.create_entity") (auto-generates)?
    └── Pass

Step 7: Unit Handling (WARNING)

Source: ifcos-errors-patterns

Code reads coordinates or dimensions from IFC files?
├── Assumes coordinates are in meters?
│   └── WARNING: ALWAYS call ifcopenshell.util.unit.calculate_unit_scale(model)
│
├── Applies unit_scale to all extracted coordinates?
│   └── Pass
│
└── Creates geometry with hardcoded values?
    └── INFO: Document assumed unit system in comments

Step 8: Property Set Handling (WARNING)

Source: ifcos-errors-patterns

Code creates property sets?
├── Creates pset without checking for existing one?
│   └── WARNING: Produces duplicate property sets; check get_psets() first
│
├── Creates pset manually without IfcRelDefinesByProperties?
│   └── BLOCKER: Orphaned pset; use api.run("pset.add_pset", ...)
│
└── Uses api.run("pset.add_pset") + api.run("pset.edit_pset")?
    └── Pass

Step 9: Performance Patterns (WARNING)

Source: ifcos-errors-performance

Code processes geometry for multiple elements?
├── Calls create_shape() in a loop for 10+ elements?
│   └── WARNING: Use ifcopenshell.geom.iterator instead (5-10x faster)
│
├── Uses geom.iterator without multiprocessing.cpu_count()?
│   └── WARNING: Pass cpu_count() for optimal parallelism
│
├── Stores all geometry shapes in memory simultaneously?
│   └── WARNING: Process each shape and discard immediately
│
├── Uses get_info(recursive=True) on large files?
│   └── WARNING: Materializes entire entity graph; extract specific attributes
│
├── Opens same large file multiple times?
│   └── WARNING: Open once, pass model reference
│
├── Iterates all entities with `for e in model` instead of by_type()?
│   └── WARNING: by_type() is O(1), full iteration is O(n)
│
├── Calls spatial.assign_container per-element instead of batching?
│   └── WARNING: Pass all products in one call
│
└── Processes 200MB+ file without gc.collect() between batches?
    └── INFO: Add gc.collect() between processing phases

Step 10: IFC2X3 Compatibility (BLOCKER)

Source: ifcos-errors-schema

Code targets or handles IFC2X3 files?
├── Creates entities without OwnerHistory?
│   └── BLOCKER in IFC2X3: OwnerHistory is REQUIRED on all IfcRoot subclasses
│
├── Uses ifcopenshell.api.run() for entity creation?
│   └── Pass (API handles OwnerHistory automatically)
│
├── Queries IfcContext (does not exist in IFC2X3)?
│   └── BLOCKER: Use IfcProject directly
│
└── Uses IfcDoorType/IfcWindowType on IFC2X3?
    └── BLOCKER: Use IfcDoorStyle/IfcWindowStyle for IFC2X3

---

Decision Trees

Decision Tree: Severity Classification

Is the issue...
├── A crash, data corruption, or invalid IFC output?
│   └── BLOCKER
│       Examples:
│       - Schema mismatch (entity not found)
│       - Invalid entity reference after removal
│       - Missing OwnerHistory in IFC2X3
│       - Dangling references from model.remove()
│       - Wrong GUID format
│       - Open transaction never closed
│
├── A potential bug, performance problem, or fragile pattern?
│   └── WARNING
│       Examples:
│       - Missing None check on get_container()
│       - create_shape() loop instead of iterator
│       - No unit scale applied
│       - Duplicate property sets
│       - Per-element API calls instead of batch
│
└── A best-practice deviation with no functional impact?
    └── INFO
        Examples:
        - Implicit schema parameter
        - Missing gc.collect() call
        - Hardcoded unit assumptions (documented)

Decision Tree: Auto-Fix Applicability

Can this issue be auto-fixed?
├── Schema entity name substitution?
│   └── YES: Replace with version-aware branching
│
├── model.remove() → api.run("root.remove_product")?
│   └── YES: Direct substitution
│
├── model.create_entity() → api.run("root.create_entity")?
│   └── YES: Add ifc_class= and name= parameters
│
├── Missing None check on utility return value?
│   └── YES: Wrap in `if result is not None:` guard
│
├── create_shape() loop → iterator?
│   └── PARTIAL: Requires restructuring; provide template
│
├── Single element → list parameter?
│   └── YES: Wrap in list brackets [element]
│
└── Missing schema check?
    └── PARTIAL: Insert model.schema check; pattern depends on context

---

Auto-Fix Patterns

Fix 1: Single Element to List Parameter (v0.8+)

# BEFORE (BLOCKER):
ifcopenshell.api.run("spatial.assign_container", model,
    product=wall, relating_structure=storey)

# AFTER:
ifcopenshell.api.run("spatial.assign_container", model,
    products=[wall], relating_structure=storey)

Fix 2: Direct Removal to Safe API Removal

# BEFORE (BLOCKER):
model.remove(wall)

# AFTER:
ifcopenshell.api.run("root.remove_product", model, product=wall)

Fix 3: Low-Level Entity Creation to API

# BEFORE (BLOCKER):
wall = model.create_entity("IfcWall",
    GlobalId=ifcopenshell.guid.new(), Name="Wall 001")

# AFTER:
wall = ifcopenshell.api.run("root.create_entity", model,
    ifc_class="IfcWall", name="Wall 001")

Fix 4: Missing None Guard

# BEFORE (BLOCKER):
container = ifcopenshell.util.element.get_container(wall)
print(container.Name)

# AFTER:
container = ifcopenshell.util.element.get_container(wall)
if container is not None:
    print(container.Name)

Fix 5: UUID to IFC GUID

# BEFORE (BLOCKER):
import uuid
wall = model.create_entity("IfcWall", GlobalId=str(uuid.uuid4()))

# AFTER:
wall = ifcopenshell.api.run("root.create_entity", model,
    ifc_class="IfcWall", name="Wall")
# Or if manual creation is required:
wall = model.create_entity("IfcWall",
    GlobalId=ifcopenshell.guid.new(), Name="Wall")

Fix 6: Iterate-and-Remove to Collect-Then-Remove

# BEFORE (BLOCKER):
for wall in model.by_type("IfcWall"):
    model.remove(wall)

# AFTER:
walls_to_remove = list(model.by_type("IfcWall"))
for wall in walls_to_remove:
    ifcopenshell.api.run("root.remove_product", model, product=wall)

Fix 7: create_shape Loop to Iterator

# BEFORE (WARNING):
# IfcOpenShell — all schema versions
for wall in model.by_type("IfcWall"):
    shape = ifcopenshell.geom.create_shape(settings, wall)
    process(shape)

# AFTER:
# IfcOpenShell — all schema versions
import multiprocessing
walls = model.by_type("IfcWall")
iterator = ifcopenshell.geom.iterator(
    settings, model, multiprocessing.cpu_count(), include=walls)
if iterator.initialize():
    while True:
        shape = iterator.get()
        process(shape)
        if not iterator.next():
            break

Fix 8: Schema-Aware Entity Selection

# BEFORE (BLOCKER):
# IfcOpenShell — assumes single schema
elements = model.by_type("IfcBuildingElement")

# AFTER:
# IfcOpenShell — all schema versions
schema = model.schema
if schema == "IFC4X3":
    elements = model.by_type("IfcBuiltElement")
else:
    elements = model.by_type("IfcBuildingElement")

---

Validation Report Format

After running all checks, produce a report in this format:

## IfcOpenShell Code Validation Report

### Summary
- BLOCKERS: [count]
- WARNINGS: [count]
- INFO: [count]

### BLOCKER Issues
1. [Line X]: [Description] — [Fix reference]

### WARNING Issues
1. [Line X]: [Description] — [Fix reference]

### INFO Issues
1. [Line X]: [Description] — [Fix reference]

### Verdict
[PASS / FAIL (if any BLOCKERS exist)]

---

Reference Links

• Validation Rules and Detection Patterns
• Before/After Validation Fix Examples
• Anti-Patterns Catalog

Dependency Skills (define the rules this validator checks)

• ifcos-syntax-fileio — File I/O patterns and transaction management
• ifcos-syntax-api — API module system, invocation patterns, parameter conventions
• ifcos-errors-patterns — Error categories, debugging strategies, None handling
• ifcos-errors-schema — Schema version differences, entity availability, migration
• ifcos-errors-performance — Geometry iterator, caching, memory management

External References

• IfcOpenShell Documentation: https://docs.ifcopenshell.org/
• IFC Schema Specifications: https://technical.buildingsmart.org/standards/ifc/ifc-schema-specifications/