diff --git a/TODO.md b/TODO.md
index 2921fec69..908b59e23 100644
--- a/TODO.md
+++ b/TODO.md
@@ -89,6 +89,41 @@ Wanted: extend the triage JSON schema so each implementation task is
 and update `appendBacklogItems` + a future milestone-escalator to read
 the structured tier rather than re-parsing markdown.
 
+## Detect manual edits to milestone files (sha-tracked, diff on change)
+
+Milestone files (`CONTEXT.md`, `MILESTONE-SUMMARY.md`, `ROADMAP.md`,
+`SUMMARY.md` + each slice's `PLAN.md` / `SUMMARY.md` + each task's
+`PLAN.md` / `SUMMARY.md`) are source of truth for SF planning. Today
+nothing notices if a human (or another agent) edits one out of band:
+SF keeps using the in-memory or DB-cached state, drifts from disk, and
+downstream tools see a different milestone than the human just wrote.
+
+Wanted: on session start (and on each autonomous-cycle entry), walk
+`.sf/milestones/**/*.md`, hash each file, compare to the last-known
+sha in `sf.db` (new column `milestone_files.sha256`,
+`milestone_files.last_seen_at`). For any file whose sha has changed:
+
+1. Compute the diff against the last-seen content (stored alongside
+   the sha as a compressed blob, or just re-fetched from git if the
+   file is tracked).
+2. Surface to the operator: "Milestone M003-abc123 CONTEXT.md changed
+   since SF last saw it — review or accept?" with the diff inline.
+3. If accepted (or in autonomous mode with a configured policy), update
+   the DB-cached version + sha and continue. If rejected, restore from
+   the last-known content.
+4. New files (sha not in DB) → import as if they were a fresh
+   `new-milestone` scaffold and add to the index.
+5. Deleted files (DB has sha but file is gone) → mark the milestone
+   archived and prompt the operator before purging.
+
+Useful for: hand-edits, cross-agent edits (another LLM in a different
+session modified the milestone), git pulls that bring in upstream
+changes to milestone files, the milestone-from-triage path I sketched
+earlier (so the autonomous loop notices its own scaffold).
+
+Storage cost: ~20 bytes per file (sha + last_seen_at) plus optional
+compressed snapshot. Negligible vs. the rest of `sf.db`.
+
 ## Phases-helpers extension-load error on every SF run
 
 Every `sf …` invocation today prints: