diff --git a/ROADMAP.md b/ROADMAP.md
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+++ b/ROADMAP.md
@@ -1,5 +1,8 @@
 # Roadmap
 
+Component-level breakdown. The milestone-level master (M1–M5, with the vision
+decisions behind it) is `docs-private/roadmap.md` in the workspace root repo.
+
 Implementation strategy and record of existing/planned features. Completed items are
 terse checklists — the requirement detail lives in `docs/architecture/overview.md` (software requirements,
 evaluated tooling, hardware) and `docs/architecture/structure.canvas` (the four-way component split).