diff --git a/api-reference/authoring-schemas.mdx b/api-reference/authoring-schemas.mdx
index de82c0d..2336afa 100644
--- a/api-reference/authoring-schemas.mdx
+++ b/api-reference/authoring-schemas.mdx
@@ -65,6 +65,23 @@ sources:
       clarity: { trait: clarity }
 ```
 
+### Advanced training overrides
+
+The optional `training:` block exposes host-level knobs that `effort` does not control. Most models do not need this section.
+
+<Accordion title="training: fields">
+
+| Field | Type | Default | Purpose |
+|-------|------|---------|---------|
+| `max_parallel_methods` | integer ≥ 1 | 4 | Concurrent method studies during Optuna optimization. Tune to host concurrency. |
+| `boundary_low` | number 0–50 | — | Fixed low percentile boundary. When set with `boundary_high`, skips the boundary sweep. |
+| `boundary_high` | number 50–100 | — | Fixed high percentile boundary. Pair with `boundary_low`. |
+| `boundary_mode` | `exclude` \| `interpolate` | `exclude` | How samples between the fixed boundaries are handled. Only used when `boundary_low`/`boundary_high` are set. |
+
+All other `training:` fields are deprecated — use the top-level `effort` field instead.
+
+</Accordion>
+
 ### Sources
 
 A source supplies training samples. Each entry has a `type`; the remaining fields depend on it.