Multi-level validation transparency: surface schema and meta-schema issues in results

[JulesGosnell]

Summary

When validating a document (m1) against a schema (m2), M3 may trigger up to three levels of validation:

• Level 0: m1 against m2 (document validation — what the user asked for)
• Level 1: m2 against m3 (schema against its meta-schema, triggered by $schema)
• Level 2: m3 against itself (meta-schema self-validation)

Currently, issues at levels 1 and 2 are either logged or silently swallowed. The caller only sees level 0 results. A malformed schema or broken meta-schema reference is invisible.

Problem

• $ref resolution failures at level 1 are logged but don't surface (ref.cljc:117)
• Meta-schema load failures are logged at INFO level (vocabulary.cljc:120)
• URI loading exceptions are silently caught (validate.cljc:250)
• Schema validation errors don't propagate down to the document validation result

Proposed output

{:valid? false
 :errors [{:schema-path [...] :message "type mismatch" ...}]
 :warnings [...]
 :schema-validation
   {:valid? true
    :warnings [{:message "format: not a valid uri" ...}]
    :meta-schema-validation
      {:valid? true}}}

Or flattened with level indicators:

{:valid? false
 :errors [...]
 :warnings [{:level :schema     :message "..." ...}
            {:level :meta-schema :message "..." ...}]}

Implementation notes

The M2/M1 flip means each level already runs through the same check-schema → compile-m2 → f1 pipeline. The challenge is threading results back down through the level transitions:

• When level 1 (schema validation) completes, its errors/warnings need to be captured in c2
• When level 0 returns its result, it attaches the level 1 results

This builds on #52 (warning system) — that issue adds the :warnings plumbing, this issue uses it across validation levels.

Depends on

• Warning system: return warnings alongside errors in validation results #52 (Warning system)