Compile-time validation failure for a deployment prelude.

Returned as {:error, %ValidationError{}} from PtcRunner.Lisp.Prelude.Compiler.compile/1 when the prelude SOURCE is malformed in a way that does not depend on a selected runtime (parse errors, reserved-namespace declarations, duplicate refs, bad visibility, invalid arity/signature metadata, and similar facts), and from PtcRunner.Lisp.Prelude.Attach.validate_requires/2 with the :prelude_attach_failed reason when a public export requires a tool operation the selected runtime does not provide.

Fields

• reason — a stable, matchable atom. Compile-time reasons: :reserved_namespace, :duplicate_ref, :invalid_visibility, :invalid_requires, :invalid_metadata, :qualified_self_reference, :missing_namespace, :invalid_namespace, :invalid_signature, :parse_error, :unbound_var, :unknown_namespace, :compile_error, :unrecognized_node. Dependency reasons (declared prelude-to-prelude deps): :unknown_dependency, :dep_ref_in_def, :dependency_cycle. Attach-time reason: :prelude_attach_failed.
• message — human-readable detail naming the offending namespace, symbol, or value. Must not contain secrets.
• details — bounded structured compiler detail for allowlisted public diagnostic rebuilding, else nil. Renderers must never forward message as a substitute for this field.
• namespace — the declaring namespace when known, else nil.
• ref — the offending export ref when known, else nil.
• form_index — zero-based position of the offending TOP-LEVEL form in the compiled source, when the failure belongs to one form, else nil. The top-level walk records it directly on walk failures and carries it on definition specs for later validation phases.
• span — {offset, length} byte span of that offending top-level form in the compiled source. A parser failure may instead carry a zero-length position span such as {byte_size(source), 0} for EOF. Other failures keep nil when no position can be proved. Top-level form spans are resolved once, at the compile boundary, by PtcRunner.Lisp.Prelude.ErrorSpan. Bundle compilation resolves them in a separate bounded worker so optional attribution cannot change the primary compile result.