model_stage_null_safe.md

ModelStageParams — add .name back + null-safe

Problem

1. Demo and HLD show params.model_stage.name but pushed code removed .name (only .cuid)
2. params.model_stage is None when no status → AttributeError on .name/.cuid access (Luis's null pointer concern)

Fix

class ModelStageParams:
    """Simple object to provide dot notation access to model stage properties."""

    def __init__(self, name=None, cuid=None):
        self.name = name
        self.cuid = cuid

Injection — always inject an instance, never None:

# Add model_stage for InventoryModel objects (same pattern as finding_type)
if self.is_inventory_model():
    if self.status:
        params["model_stage"] = ModelStageParams(
            name=self.status.name, cuid=self.status.cuid
        )
    else:
        params["model_stage"] = ModelStageParams()  # .name=None, .cuid=None

Result

Expression	No status	Has status
params.model_stage.name	None (no crash)	"Production"
params.model_stage.cuid	None (no crash)	"clx1a2b3c"
params.model_stage.name == "Production"	False (correct)	True
params.model_stage.cuid == "clx1a2b3c"	False (correct)	True

No guard pattern needed. Users can't hit AttributeError. .name back for readability, .cuid for rename-safety.