diff --git a/AGENTS.md b/AGENTS.md
index b79c8bbe..0f6ff370 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -351,8 +351,11 @@ Current Research Stack cornfield ref (for cross-repo lookup only):
 - `tests/test_q16_roundtrip.py` is the Python ↔ C roundtrip test harness
   (21 tests, all green).
 - `python/pist_matrix_builder.py` and `python/validate_rrc_predictions.py` are
-  I/O-only raw-feature shims.  They contain no admissibility logic and no Float
-  arithmetic.
+   I/O-only raw-feature shims.  They contain no admissibility logic and no Float
+   arithmetic.
+- `python/hachimoji_citation.py` — Equation → Hachimoji state classifier → arXiv
+   citation retriever. Mirrors `formal/CoreFormalism/HachimojiCodec.lean` exactly.
+   Uses hybrid_search SQL function for trigram+pgvector RRF retrieval.
 - Build baselines and session summaries are recorded in
   `docs/build_logs/YYYY-MM-DD_session_build_baseline.md` (see
   `docs/build_logs/2026-06-21_session_build_baseline.md`).