diff --git a/docs/BRANCH-FORK-MAINTENANCE.md b/docs/BRANCH-FORK-MAINTENANCE.md
index 59a3988..4891f38 100644
--- a/docs/BRANCH-FORK-MAINTENANCE.md
+++ b/docs/BRANCH-FORK-MAINTENANCE.md
@@ -61,7 +61,7 @@ The same files conflict every time:
 | `.env.example` | Combine: main's entries + fork/branch-specific entries |
 | `repo-tokens/badge.svg` | Take main's version (auto-generated) |
 
-Source code changes (e.g. `src/types.ts`, `src/index.ts`) usually auto-merge cleanly, but can conflict if both sides modify the same lines. Build and test after every forward merge.
+Source code changes (e.g. `src/types.ts`, `src/index.ts`) usually auto-merge cleanly, but can conflict if both sides modify the same lines. **Always build and test after every forward merge** — auto-merged code can be silently wrong (e.g. referencing a renamed function or using a removed parameter) even when git reports no conflicts.
 
 ## When to merge forward