Diagnostics

Validation reports every problem it finds, each with a stable code, a path into the manifest, and a message that says how to fix it. With source maps (aleph check adds them), each diagnostic also points at the line in your app:

✖ unbounded_limit at app.ts:24:5 (routes[1].plan.body[0].op.limit)
  query limit must have a static upper bound, found int. Use a literal, an int input with a max, or $.min(limit, N).

Codes are stable: tools and agents can match on them.

Code	Meaning
`invalid_manifest`	The JSON doesn't match the manifest format.
`unsupported_format_version`	The manifest's `formatVersion` isn't one this core reads.
`invalid_name`	A name isn't 1-64 characters of letters, digits, and `_`.
`invalid_field_type`	A field type is malformed: min above max, an empty enum, nested arrays, objects too deep, a bad decimal scale.
`invalid_default`	A default doesn't fit its field.
`invalid_key`	An entity's key is empty, repeats a field, or uses an optional, array, or object field.
`invalid_index`	An index has no fields or uses an unorderable field.
`row_too_large`	A row's worst-case size is over 64 KB. Lower string and array maximums.
`unknown_entity`	The plan names an entity that isn't declared.
`unknown_field`	A field, object field, or state field isn't declared.
`unknown_index`	A query names an undeclared index.
`unknown_counter`	A counter isn't declared.
`unknown_error`	`fail` or `ensure` names an error the route or handler doesn't declare.
`unknown_input`	The plan reads an input the route doesn't declare.
`duplicate_route_id`	Two routes share an id.
`duplicate_route`	Two routes have the same method and path shape.
`invalid_path`	A path doesn't start with `/` or has empty segments.
`path_param_mismatch`	The path's `:params` don't match the declared params.
`invalid_error_status`	An error status isn't 400-599, or a success status isn't 200-399.
`undefined_var`	A plan uses a variable outside its scope.
`duplicate_var`	A plan defines a variable twice.
`missing_key_field`	A key is missing a field, or an insert has no value for a key field.
`missing_required_field`	An insert or object is missing a required field.
`immutable_key_field`	An update tries to change a key field.
`invalid_prefix`	A prefix or `anyOf` doesn't fit the scanned key, or `anyOf` is combined with paging.
`invalid_counter_key`	A counter's grouping, aggregate, or shards are invalid.
`unbounded_list`	A loop or aggregate is over something without a known maximum length.
`unbounded_limit`	A query's `limit` has no static upper bound. Use a constant, an int input with a max, or `$.min(limit, N)`.
`write_in_pure_block`	A `map` or `filter` body writes, releases an effect, or returns.
`non_exhaustive_match`	A `$.match` doesn't cover every enum value and has no `_` case.
`unknown_match_case`	A `$.match` case isn't a value of the enum.
`invalid_field_access`	A field is read from something that isn't a row or object.
`type_mismatch`	An operand, written value, or response has the wrong type, or may be `null` where it can't be.
`invalid_predicate`	A row expression (index, counter, invariant) depends on something other than the row.
`invalid_auth`	A route's auth rule is malformed.
`unknown_role`	A route requires an undeclared role.
`unknown_scope`	A route requires an undeclared API key scope.
`invalid_idempotency`	An idempotency TTL is out of range.
`immutable_entity`	An append-only entity is updated or deleted.
`unknown_event`	An event isn't declared.
`unknown_queue`	A queue isn't declared.
`unknown_channel`	A channel isn't declared.
`unknown_bucket`	A bucket isn't declared.
`unknown_integration`	An integration isn't declared.
`unknown_operation`	An integration operation isn't declared, or is called with the wrong mode.
`invalid_payload`	Payload or input values don't match their declared fields.
`invalid_handler`	A handler's trigger, schedule, or workflow transition is invalid.
`invalid_declaration`	A declaration is invalid: a queue without a handler, a workflow without its start step, a bad CORS origin, or a versioned entity without `version`.
`invalid_route`	A route-level rule is broken: a reserved header, a webhook that isn't public `POST`, or `OPTIONS` routes.
`invalid_range`	A query range has two lower or two upper bounds, or no field to bound.
`invalid_expression`	An expression's static arguments are invalid: a bad regex, an unknown time zone, a bad pattern or scale.
`over_budget`	The worst case of a route or handler is over a limit. Lower the bounds that drive it, or move the work to a job.
`trigger_cycle`	Handlers set each other off in a loop (a trigger that writes its own entity, events that emit each other, a queue job that enqueues itself), so a chain would never end. Break the cycle, or declare `maxDepth` on every handler in it.