Validation Error Catalogue

Every error message loom check can emit, what triggers it, and how to fix it. Errors are reported with a dotted path identifying the offending node (e.g. fields[2].type).

Header errors

Error	Trigger	Fix
`model: is required`	The `model:` key is missing	Add a top-level `model: <PascalCaseName>`
`model: "<name>" must be PascalCase`	Model name is lowercase, snake_case, or has spaces	Rename to PascalCase: `Customer`, `InvoiceItem`
`label: is required`	Missing `label:`	Add a human-readable `label:`
`icon: is required`	Missing `icon:`	Add a Lucide icon name (`users`, `file-text`, `tag`, …)

Fields errors

Error	Trigger	Fix
`fields: must declare at least one field`	Empty `fields:` list	Add at least one field
`fields[N].name: is required`	Field's `name:` missing	Add a snake_case `name:`
`fields[N].name: "<name>" must be snake_case`	Name has uppercase or hyphens	Rename: `companyName` → `company_name`
`fields[N].name: duplicate field name "<name>"`	Two fields with the same name	Rename one
`fields[N].type: is required`	Field's `type:` missing	Add a recognised type
`fields[N].type: "<type>" is not a recognised field type`	Typo in type	See Reference → Field Type Catalogue
`fields[N].options: field type "<t>" requires at least one option`	`select`/`radio`/`multiselect` with no `options`	Add `options:`
`fields[N].options: field type "<t>" does not support options`	Field that isn't `select`/`radio`/`multiselect` has `options`	Remove `options:`
`fields[N].options[M].value: is required`	Option missing `value:`	Add `value:`
`fields[N].options[M].label: is required`	Option missing `label:`	Add `label:`
`fields[N].target: link field requires a target model`	`link` without `target:`	Add `target: <PascalCaseModel>`
`fields[N].target: field type "<t>" does not use target`	Non-link field with `target:`	Remove `target:`
`fields[N].target: "<t>" must be PascalCase model name`	Target isn't PascalCase	Rename to PascalCase
`fields[N]: min (X) is greater than max (Y)`	Inverted range	Swap min/max

Relationships errors

Error	Trigger	Fix
`relationships[N].type: is required`	Missing `type:`	Add `type: has_many` / `belongs_to` / `many_to_many`
`relationships[N].type: "<t>" is not a valid relationship type`	Typo	One of `has_many`, `belongs_to`, `many_to_many`
`relationships[N].target: is required`	Missing `target:`	Add target Thread name
`relationships[N].target: "<t>" must be PascalCase model name`	Target isn't PascalCase	Rename
`relationships[N].through: many_to_many requires a 'through' join model`	M2M missing through	Add `through: <PascalCaseJoinModel>`
`relationships[N].through: through is only valid for many_to_many`	Non-M2M with `through`	Remove

Permissions errors

Error	Trigger	Fix
`permissions[N].role: is required`	Missing role	Add `role: <RoleName>`
`permissions[N].can: must be "all" or a non-empty list of actions`	Empty `can`	Use `all` or `[read, create, ...]`
`permissions[N].can[M]: "<action>" is not a valid action`	Typo	One of `read`, `create`, `update`, `delete`

ListView / FormView errors

Error	Trigger	Fix
`list_view.columns[N]: "<f>" is not a declared field`	Column references missing field	Fix the column name or declare the field
`list_view.filters[N]: "<f>" is not a declared field`	Same, for filters
`list_view.default_sort: "<f>" is not a declared field`	Same, for default sort
`list_view.sort_order: "<x>" must be "asc" or "desc"`	Bad sort order	Use `asc` or `desc`
`list_view.page_size: must be >= 0`	Negative page size	Use a positive integer
`form_view.sections[N].columns: must be 1 or 2, got X`	Bad column count	1 or 2 only
`form_view.sections[N].fields[M]: "<f>" is not a declared field`	Section references missing field	Fix
`form_view.related_lists[N].model: is required`	Missing related model	Add
`form_view.related_lists[N].model: "<m>" must be PascalCase model name`	Bad casing	Rename

Hooks errors

Error	Trigger	Fix
`hooks.<event>: "<name>" is not a valid Go function name`	Hook name has invalid chars	Use letters/digits/underscores, start with a letter

Strict-mode YAML errors

loom check uses KnownFields(true), so any unrecognised key surfaces a YAML decode error like:

field requried not found in type schema.Field

The fix is always the same: correct the typo (requried → required).