diff --git a/skills/omnigraph/SKILL.md b/skills/omnigraph/SKILL.md
index 49a19b65..ffbf9522 100644
--- a/skills/omnigraph/SKILL.md
+++ b/skills/omnigraph/SKILL.md
@@ -377,7 +377,7 @@ These are the traps most likely to bite. Scan this table before debugging any pa
 | `load --mode merge` after `@embed` source change | stale embeddings | `omnigraph embed --reembed_all` or `load --mode overwrite` |
 | `schema apply` with feature branches open | rejected | Merge or delete branches first |
 | `nearest(...)` / `bm25(...)` / `rrf(...)` without `limit` | compile error | Add `limit N` |
-| Adding non-nullable property without backfill | unsupported migration | Make optional → backfill → tighten in follow-up apply |
+| Adding non-nullable property without backfill | unsupported migration | Make optional → backfill; keep it optional (tightening `T?` → `T` is refused, OG-MF-106) |
 | `omnigraph init --json` | `unexpected argument --json` | `init` doesn't support `--json`; drop the flag |
 | `omnigraph init` on an already-initialized URI | `AlreadyInitialized` error (v0.6.0+) | `--force` to re-init (skips the schema preflight; does **not** purge data) |
 | `schema apply` dropping a property/type | soft-dropped or rejected (no data loss) | add `--allow-data-loss` to actually drop the column |
diff --git a/skills/omnigraph/references/queries.md b/skills/omnigraph/references/queries.md
index 32498ab0..f2415786 100644
--- a/skills/omnigraph/references/queries.md
+++ b/skills/omnigraph/references/queries.md
@@ -117,7 +117,7 @@ query employees_of($company: String) {
 
 ### Undirected traversal (omnigraph >= 0.8.1)
 
-For symmetric relations (same-endpoint-type edges like `Related: Issue -> Issue`),
+For symmetric relations (same-endpoint-type edges like `IssueRelated: Issue -> Issue`),
 angle brackets match the edge in **either direction**, deduplicated — one
 pattern replaces querying both directions and merging:
 
@@ -291,7 +291,7 @@ query add_and_link($slug: String, $pattern: String, $createdAt: DateTime, $updat
 
 There's no `upsert` keyword at the query level — use `load --mode merge` for bulk upsert.
 
-> **Insert/update-only OR delete-only (the D₂ rule).** A single mutation query may contain inserts and updates, **or** deletes — never both. Mixing a `delete` with an `insert`/`update` in the same query is rejected at parse time. (Inserts/updates go through a staged two-phase publish; deletes inline-commit — omnigraph doesn't yet use Lance's two-phase delete API (it shipped in Lance 7.0.0 but isn't wired in) — so they can't share one atomic statement.) Split a delete-then-insert into two separate mutations.
+> **Insert/update-only OR delete-only (the D₂ rule).** A single mutation query may contain inserts and updates, **or** deletes — never both. Mixing a `delete` with an `insert`/`update` in the same query is rejected at parse time. (Deletes stage through the same two-phase publish as inserts/updates since 0.8.0; the D₂ split is a deliberate semantic boundary — one mutation query is constructive XOR destructive, keeping read-your-writes unambiguous — not an implementation gap.) Split a delete-then-insert into two separate mutations.
 
 ### Date and DateTime values