diff --git a/SECURITY.md b/SECURITY.md
index 85232c0..4b40be1 100644
--- a/SECURITY.md
+++ b/SECURITY.md
@@ -34,3 +34,22 @@ appreciated — please give us time to release a fix before any public disclosur
   project directories. Review the paths you grant access to.
 - `qti-core` produces QTI packages from local markdown; it makes no network calls
   as part of generation.
+
+## Data protection
+
+This is a public repository. QuestionForge works with a teacher's exam material
+in local project directories — none of that material belongs here. Git history
+is permanent, so the rules below apply to code, tests, examples, documentation
+and commit messages alike.
+
+- **Never commit real personal data:** names (students, colleagues, teachers),
+  school or institution names, personal-identity numbers, file paths containing
+  a username (`/Users/...`), or secrets (API keys, tokens, `.env`).
+- **Never commit real exam material:** actual exam questions, question banks and
+  assessment data stay in your local project. Examples and test fixtures use
+  fabricated questions only.
+- **Use fabricated or anonymised data in every example and test** — for example
+  `School A`, `Colleague_A`, `/path/to/project`, an invented question.
+- **Already committed something real?** Deleting the file is not enough — it
+  stays in the git history forever. Stop, scrub the history, rotate any exposed
+  secret, and resolve it before the next push.
diff --git a/docs/decisions/017-track-repo-policy-rules.md b/docs/decisions/017-track-repo-policy-rules.md
index 509c773..488df93 100644
--- a/docs/decisions/017-track-repo-policy-rules.md
+++ b/docs/decisions/017-track-repo-policy-rules.md
@@ -1,7 +1,8 @@
 ---
 type: decision
-status: active
+status: superseded
 created: 2026-06-24
+superseded: 2026-07-07
 origin: code
 project: QuestionForge
 relates_to: [ADR-015, ADR-016]
@@ -9,6 +10,14 @@ relates_to: [ADR-015, ADR-016]
 
 # ADR-017: Track the three repo-policy rules in `.claude/rules/`
 
+> **Superseded** by ACDM ADR-017 (*Rule distribution — `.claude/` is dev-tooling;
+> public policy lives in conventional docs*, 2026-06-24) and walked back in #33:
+> the "read by repo-tooling" rationale below was wrong — the tooling that reads
+> these rules is local and has them on disk regardless of git-tracking, and
+> `.claude/rules/*.md` are agent instructions, not contributor-facing policy.
+> `.claude/` is now wholly gitignored; the public data-protection policy lives
+> in `SECURITY.md`. The text below is kept as the historical record.
+
 ## Context
 
 `.claude/` holds Claude Code / ACDM configuration. Historically the whole