diff --git a/SKILL.md b/SKILL.md
index fb4ddc1..834ab02 100644
--- a/SKILL.md
+++ b/SKILL.md
@@ -243,8 +243,12 @@ proceed, unless an item on the not-yet-supported list below applies: without an
 answer, stop there and report it.
 
 **NOT yet supported — warn the user if the project has these:**
-- Build-time custom commands / generated code. Configure-time generated
-  files are handled by you, not the tool: see the reference guide.
+- Build-time generation with **no clear Bazel mapping**: a sub-build the
+  reference model does not show (autotools, a vendored fork's own build) whose
+  outputs the binaries link. Other codegen and configure-time generated files
+  are yours to migrate: see
+  [Create initial BUILD.bazel files](#create-build-files) and the reference
+  guide.
 - Per-test-binary identity alignment, and include search **order** (presence
   only) — both have planned follow-ups
 - Packaging / install rules
@@ -301,6 +305,10 @@ silently: a genrule cannot see `.git` from the sandbox, and the binary reports
 an "unknown version". Feed them through `--workspace_status_command` to a
 `stamp = 1` rule.
 
+**Build-time codegen** that maps to a `genrule` over a host tool (bison/flex) or
+to a ruleset (protoc) is yours to migrate: use the project's declared generator
+version.
+
 The reference guide covers what is specific to translating its build system
 (for CMake: the build type and configure-time generated files).
 
diff --git a/docs/REFERENCE-cmake.md b/docs/REFERENCE-cmake.md
index 37c6c98..9008557 100644
--- a/docs/REFERENCE-cmake.md
+++ b/docs/REFERENCE-cmake.md
@@ -14,8 +14,10 @@ as the reference build.
 
 When [confirming scope](../SKILL.md#confirm-scope), inspect `CMakeLists.txt`
 for these and surface them before proceeding:
-- Build-time generated code: `add_custom_command`, protoc or other codegen
-  steps. `configure_file` is handled by you, not the tool: see
+- Build-time generation with no clear Bazel mapping: a sub-build the CMake
+  model does not show (autotools, a vendored fork's own build) whose outputs
+  the binaries link. Other codegen (`add_custom_command`, protoc) is yours to
+  migrate, and so is `configure_file`: see
   [Configure-time generated files](#configure-time-generated-files).
 - `find_package` of non-system libraries. There is no automatic
   `find_package` → bzlmod resolution; each one must be mapped by hand.