diff --git a/CLAUDE.md b/CLAUDE.md
index af30721e..fec36b24 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -7,7 +7,7 @@ Guidance for Claude Code sessions working in this repository.
 **jquantstats** — portfolio analytics for quants, built on [Polars](https://pola.rs/)
 (zero pandas at runtime) with interactive [Plotly](https://plotly.com/python/) charts.
 Python `>=3.11`, MIT-licensed, published to PyPI. This is a
-[Rhiza](https://github.com/jebel-quant/rhiza)-managed repository (template `v1.1.2`).
+[Rhiza](https://github.com/jebel-quant/rhiza)-managed repository (template `v1.2.0`).
 
 ## Commands
 
diff --git a/README.md b/README.md
index e31837be..1386f208 100644
--- a/README.md
+++ b/README.md
@@ -390,6 +390,11 @@ categorized metric tables, rendered via Jinja2 templates.
 
 For detailed documentation, visit [jQuantStats Documentation](https://jebel-quant.github.io/jquantstats).
 
+The public API (`Portfolio` and `Data`) follows [Semantic Versioning](https://semver.org/)
+from **v1.0.0** onwards; see the
+[API Stability & deprecation policy](https://jebel-quant.github.io/jquantstats/STABILITY/)
+for the exact stability guarantee and deprecation timeline.
+
 ## Contributing
 
 Contributions are welcome! Please feel free to submit a Pull Request.
diff --git a/pyproject.toml b/pyproject.toml
index d26bc31c..c34aa3eb 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -147,3 +147,11 @@ ignore-init-method = true
 ignore-magic = true
 ignore-overloaded-functions = true
 
+# Test-layout parity (rhiza check_test_layout): tests here are organised by
+# behaviour under tests/test_jquantstats/… rather than mirroring src/ 1:1, and
+# per-module coverage is guaranteed by the 100% line+branch pytest gate above
+# (a stronger guarantee than file-mirroring). Opt out of the 1:1 mirror rule.
+[tool.check_test_layout]
+enforce = false
+reason = "Tests are organised by behaviour under tests/test_jquantstats/; per-module coverage is guaranteed by the 100% pytest coverage gate rather than 1:1 file mirroring."
+
diff --git a/src/jquantstats/_portfolio_cost.py b/src/jquantstats/_portfolio_cost.py
index 3a937cd4..3b672305 100644
--- a/src/jquantstats/_portfolio_cost.py
+++ b/src/jquantstats/_portfolio_cost.py
@@ -4,9 +4,11 @@
 
 import math
 
+import numpy as np
 import polars as pl
 
 from ._portfolio_base import _PortfolioMembers
+from ._stats._core import _std_is_negligible
 from .exceptions import InvalidMaxBpsError, NegativeCostBpsError
 
 
@@ -181,10 +183,6 @@ def trading_cost_impact(self, max_bps: int = 20) -> pl.DataFrame:
         """
         if not isinstance(max_bps, int) or max_bps < 1:
             raise InvalidMaxBpsError(max_bps)
-        import numpy as np
-
-        from ._stats._core import _std_is_negligible
-
         periods = self.data._periods_per_year  # one Data object, outside the loop
         sqrt_periods = float(np.sqrt(periods))
         cost_levels = list(range(max_bps + 1))
diff --git a/src/jquantstats/data.py b/src/jquantstats/data.py
index ca314755..76bc5e99 100644
--- a/src/jquantstats/data.py
+++ b/src/jquantstats/data.py
@@ -520,6 +520,9 @@ def plots(self) -> DataPlots:
             DataPlots: An instance of the DataPlots class initialized with this data.
 
         """
+        # Deferred to break the data <-> accessors import cycle: _plots imports
+        # DataLike from this module, so hoisting this to module top re-forms the
+        # cycle. Keep the import local.
         from ._plots import DataPlots
 
         return DataPlots(self)
@@ -532,6 +535,7 @@ def stats(self) -> Stats:
             Stats: An instance of the Stats class initialized with this data.
 
         """
+        # Deferred to break the data <-> accessors import cycle (see .plots).
         from ._stats import Stats
 
         return Stats(self)
@@ -544,6 +548,7 @@ def reports(self) -> Reports:
             Reports: An instance of the Reports class initialized with this data.
 
         """
+        # Deferred to break the data <-> accessors import cycle (see .plots).
         from ._reports import Reports
 
         return Reports(self)
@@ -556,6 +561,7 @@ def utils(self) -> DataUtils:
             DataUtils: An instance of the DataUtils class initialized with this data.
 
         """
+        # Deferred to break the data <-> accessors import cycle (see .plots).
         from ._utils import DataUtils
 
         return DataUtils(self)