@@ -1,6 +1,7 @@
 # Architecture
 
-**Analysis Date:** 2026-10-15 **Branch analysed:** `develop` @ `66adaf54`
+**Analysis Date:** 2026-10-15 **Branch analysed:** `develop` @
+`66adaf54`
 
 ## Pattern Overview
 
@@ -27,8 +28,8 @@ is computed by pluggable engine wrappers (refnx, refl1d) behind
 - Inequality constraints are enforced by patching the BUMPS driver in
   the core's namespace, because the core offers no hook
 - Shared objects (one material in two layers, one assembly in two
-  models) serialize once through `sample/references.py` (`file_format`
-  3)
+  models) serialize once through `sample/references.py`
+  (`file_format` 3)
 
 ## Layers
 
@@ -64,14 +65,16 @@ is computed by pluggable engine wrappers (refnx, refl1d) behind
 - Purpose: Post-hoc posterior analysis and chain persistence
 - Location: `src/easyreflectometry/analysis/bayesian.py`
 - Contains: `PosteriorResults` (summary, corner, trace, distribution,
-  credible_interval, gelman_rubin, save), `posterior_predictive_*`,
-  `save_posterior` / `load_posterior` with fingerprinted sidecar
+  credible*interval, gelman_rubin, save),
+  `posterior_predictive*\*`, `save_posterior`/`load_posterior` with
+  fingerprinted sidecar
 - Depends on: plotly (required), arviz (optional), numpy
 
 **Model / Sample Layer:**
 
 - Purpose: Physical description of the sample and measurement
-- Location: `src/easyreflectometry/model/`, `src/easyreflectometry/sample/`
+- Location: `src/easyreflectometry/model/`,
+  `src/easyreflectometry/sample/`
 - Contains: `Model` (scale, background, resolution, `total_thickness`
   derived parameter), `Sample` and assemblies/layers/materials,
   `LayerMagnetism`, `MaterialDensity.sld_coupled`, `volume_fraction`,
@@ -119,21 +122,22 @@ is computed by pluggable engine wrappers (refnx, refl1d) behind
 
 **Classical Fit (project path):**
 
-1. GUI/user calls `Project.prepare_fit(experiments=None, objective=None, skip_invalid=False)`
+1. GUI/user calls
+   `Project.prepare_fit(experiments=None, objective=None, skip_invalid=False)`
 2. `_fit_scope` selects experiments with `include_in_fit` and a model;
    `_fitter_for` builds `MultiFitter.for_experiments(...)` with a deep
    copy of `fit_settings` and a weak `constraints_factory_provider`
 3. `MultiFitter.prepare` applies the objective (`hybrid` default:
-   Mighell for zero-variance points, WLS otherwise), binds each dataset's
-   fit function to its own resolution (`_resolution_for_fitted_points`
-   for `legacy_mask`), collects `added_roots` (free parameters of
-   left-out models that fitted parameters follow), builds the core
-   fitter via `_core_fitter_for` + `FitSettings.configure`, checks
-   preconditions (finite bounds for engines that need them, warns on
-   starts at bounds)
+   Mighell for zero-variance points, WLS otherwise), binds each
+   dataset's fit function to its own resolution
+   (`_resolution_for_fitted_points` for `legacy_mask`), collects
+   `added_roots` (free parameters of left-out models that fitted
+   parameters follow), builds the core fitter via `_core_fitter_for` +
+   `FitSettings.configure`, checks preconditions (finite bounds for
+   engines that need them, warns on starts at bounds)
 4. Caller runs `prepared.execute(**kwargs)` or `core_fitter.fit(...)` in
-   a thread; the `_ConstrainedEasyScienceMultiFitter.fit` property
-   wraps the call in `_bumps_constraints.applied(factory)`
+   a thread; the `_ConstrainedEasyScienceMultiFitter.fit` property wraps
+   the call in `_bumps_constraints.applied(factory)`
 5. `Project.record_fit(prepared, results, status)` computes classical
    metrics from the measured arrays (`prepared.finalize`), stores a
    `FitRun` on `last_fit` and pushes results to `project.fitter`
@@ -148,22 +152,23 @@ is computed by pluggable engine wrappers (refnx, refl1d) behind
 
 **Polarized Fit:**
 
-- `fit_polarized(polarized_dataset)` or `for_experiments([...])`: one fit
-  function per spin channel, all against one model, each bound to its
-  channel via `CalculatorFactory.fit_func_for(channel, resolution)`.
+- `fit_polarized(polarized_dataset)` or `for_experiments([...])`: one
+  fit function per spin channel, all against one model, each bound to
+  its channel via `CalculatorFactory.fit_func_for(channel, resolution)`.
   Structural parameters shared, magnetic parameters constrained by all
   channels.
 
 **Bayesian MCMC:**
 
 1. `Project.prepare_sample()` → `for_experiments` fitter with settings
    snapshot; or `fitter.mcmc_sample(data)` directly
-2. `mcmc_sample` requires a BUMPS minimizer (`minimizer.package ==
-'bumps'`), refuses all-zero variances unless `objective='mighell'`,
-   calls `prepare(action='sampling')`
+2. `mcmc_sample` requires a BUMPS minimizer
+   (`minimizer.package == 'bumps'`), refuses all-zero variances unless
+   `objective='mighell'`, calls `prepare(action='sampling')`
 3. Builds `Sampler(core_fitter, x, y, weights)` inside the constraints
-   context, patches `sampler.extend` to re-enter it, keeps the sampler on
-   `fitter.sampler`, runs `sampler.sample(samples, burn, thin, population, sampler_kwargs, progress_callback, abort_test)`
+   context, patches `sampler.extend` to re-enter it, keeps the sampler
+   on `fitter.sampler`, runs
+   `sampler.sample(samples, burn, thin, population, sampler_kwargs, progress_callback, abort_test)`
 4. Returns `{'draws', 'param_names', 'state', 'logp'}`; user wraps in
    `PosteriorResults` or calls `save_posterior`
 
@@ -191,10 +196,10 @@ is computed by pluggable engine wrappers (refnx, refl1d) behind
 
 ## Key Abstractions
 
-**`PreparedFit` (fitting.py):** Snapshot pattern. Everything a run needs,
-fixed at prepare time; owns copies of measured arrays, the configured
-core fitter and both full-resolution (`curve_funcs`) and fitted-point
-(`fit_funcs`) evaluators.
+**`PreparedFit` (fitting.py):** Snapshot pattern. Everything a run
+needs, fixed at prepare time; owns copies of measured arrays, the
+configured core fitter and both full-resolution (`curve_funcs`) and
+fitted-point (`fit_funcs`) evaluators.
 
 **`FitRun` (fitting.py):** Frozen record of a run (status, minimizer,
 objective, inputs by experiment key, pooled and per-dataset statistics).
@@ -205,10 +210,10 @@ Outlives model changes; `remapped()` follows experiment re-keying.
 validated by `MinimizerOption` schemas). `configure(fitter)` and
 `engine_kwargs()` are the two consumers.
 
-**`_ConstrainedEasyScienceMultiFitter` / `_bumps_constraints`:** Property
-override plus monkeypatch. The subclass overrides the core's read-only
-`fit` property so the raw `easy_science_multi_fitter.fit(...)` path
-resolves the owner's constraints provider in the calling thread and
+**`_ConstrainedEasyScienceMultiFitter` / `_bumps_constraints`:**
+Property override plus monkeypatch. The subclass overrides the core's
+read-only `fit` property so the raw `easy_science_multi_fitter.fit(...)`
+path resolves the owner's constraints provider in the calling thread and
 consumes an explicit `constraints_factory` keyword (the core would
 swallow it via `**kwargs`). `install()`, run at import of
 `_bumps_constraints`, wraps `minimizer_bumps.FitDriver` so each
@@ -220,15 +225,16 @@ Non-BUMPS engines raise `NON_BUMPS_ERROR`.
 restricted symbol table; `build_constraints_factory` returns BUMPS
 penalty callables.
 
-**Contrasts (`contrasts.py`):** A contrast is an ordinary `Model` sharing
-structure with a reference by identity or by `constrain_equal`.
+**Contrasts (`contrasts.py`):** A contrast is an ordinary `Model`
+sharing structure with a reference by identity or by `constrain_equal`.
 `derive_contrast` copies touched assemblies, shares the rest and ties
 parameters; `plan_link` / `apply_link` / `unlink` manage equalities
 between two models of one layout with full state snapshots.
 
 **`CalculatorBase` / `WrapperBase` / `CalculatorFactory`:** Template +
-Adapter + Factory. Items are claimed per calculator (`_claim`), per-model
-resolution registry, magnetism toggles, channel-bound fit functions.
+Adapter + Factory. Items are claimed per calculator (`_claim`),
+per-model resolution registry, magnetism toggles, channel-bound fit
+functions.
 
 **`references` (sample/references.py):** Context-managed shared-object
 serialization (`writing()`, `reading(report)`, `suspended()`), with
@@ -278,8 +284,8 @@ issues; refuse silent degradation.
 handler configured. `warnings` is the main user-facing channel.
 
 **Validation:** `FitSettings.validate`, `MinimizerOption.validate`,
-`InequalitySpec.validate_syntax` + `check_units`, ORSO column validation,
-`_check_fit_preconditions`.
+`InequalitySpec.validate_syntax` + `check_units`, ORSO column
+validation, `_check_fit_preconditions`.
 
 **Threading:** The constraints factory lives in a `contextvars`
 variable, resolved in the calling thread; `PreparedFit` owns array
 
@@ -1,6 +1,7 @@
 # Codebase Concerns
 
-**Analysis Date:** 2026-10-15 **Branch analysed:** `develop` @ `66adaf54`
+**Analysis Date:** 2026-10-15 **Branch analysed:** `develop` @
+`66adaf54`
 
 ## Summary
 
@@ -24,12 +25,13 @@ goes through the core `Sampler`. The concerns below are what remains.
 inside the core's `minimizer_bumps` namespace and inspects
 `problem.models[0].pars`. Any core refactor (importing `FitDriver`
 differently, building the problem elsewhere, renaming `.pars`) silently
-disables every inequality constraint; the shim passes untouched
-problems through without complaint.
+disables every inequality constraint; the shim passes untouched problems
+through without complaint.
 
 **Files:** `src/easyreflectometry/_bumps_constraints.py`,
 `src/easyreflectometry/fitting.py` (`_constraints`,
-`_keep_constraints_on_extend`), `tests/unit/test_bumps_constraints_shim.py`
+`_keep_constraints_on_extend`),
+`tests/unit/test_bumps_constraints_shim.py`
 
 **Impact:** High. Physics silently dropped on a core upgrade.
 
@@ -53,8 +55,8 @@ against, and 3.0 is excluded by the pin.
 core release ships.
 
 **Fix approach:** Add a CI job (allowed to fail) installing core from
-`release-3.0`; list the library's core API surface
-(`Sampler`, `MultiFitter._precompute_reshaping`, `MINIMIZER_PARAMETER_PREFIX`,
+`release-3.0`; list the library's core API surface (`Sampler`,
+`MultiFitter._precompute_reshaping`, `MINIMIZER_PARAMETER_PREFIX`,
 `InterfaceFactoryTemplate`, `minimizer_bumps.FitDriver`) and check it
 against the branch.
 
@@ -66,7 +68,8 @@ against the branch.
 `ItemContainer` from `interface_factory` are not public core API.
 
 **Files:** `analysis/bayesian.py`, `project.py`,
-`sample/collections/base_collection.py`, `calculators/calculator_base.py`
+`sample/collections/base_collection.py`,
+`calculators/calculator_base.py`
 
 **Impact:** Medium.
 
@@ -96,9 +99,9 @@ helpers). Keep `Project` as the facade.
 ### `fitting.py` (1428 lines) and `analysis/bayesian.py` (1412 lines)
 
 **Issue:** `bayesian.py` is mostly plotly styling constants and
-hand-rolled contour/density code for corner plots; `fitting.py`
-combines data preparation, settings, constraints wiring and five public
-fit paths.
+hand-rolled contour/density code for corner plots; `fitting.py` combines
+data preparation, settings, constraints wiring and five public fit
+paths.
 
 **Impact:** Low-Medium.
 
@@ -128,7 +131,8 @@ shared objects, an experiment left out of the fit, duplicate model
 names. A user may save a file in 1.9 that 1.8 refuses without an obvious
 reason.
 
-**Files:** `project.py` (`_needs_new_format`, `_as_dict_add_experiments`)
+**Files:** `project.py` (`_needs_new_format`,
+`_as_dict_add_experiments`)
 
 **Impact:** Medium. Document in release notes; already in CHANGELOG.
 
@@ -175,8 +179,9 @@ slow cases) under `integration/`.
 
 **Issue:** `fitter.sampler.extend()` after constraints, and
 `save_posterior`/`load_posterior` fingerprint mismatch handling, have
-limited coverage (`TestMCMCSample*` in `test_fitting.py`, `test_bayesian.py`);
-all real DREAM runs are `slow` and only run on PRs/develop.
+limited coverage (`TestMCMCSample*` in `test_fitting.py`,
+`test_bayesian.py`); all real DREAM runs are `slow` and only run on
+PRs/develop.
 
 **Impact:** Medium.
 
@@ -230,9 +235,9 @@ and an accidental `git add .` would commit them.
 
 **Impact:** Low.
 
-**Fix approach:** Add `.planning/`, `.claude/`, `MD/` to `.gitignore` (or
-a global excludes file); decide whether `examples/` and `integration/`
-belong in the repo.
+**Fix approach:** Add `.planning/`, `.claude/`, `MD/` to `.gitignore`
+(or a global excludes file); decide whether `examples/` and
+`integration/` belong in the repo.
 
 ### Docstring tooling disabled
 
 
@@ -1,6 +1,7 @@
 # External Integrations
 
-**Analysis Date:** 2026-10-15 **Branch analysed:** `develop` @ `66adaf54`
+**Analysis Date:** 2026-10-15 **Branch analysed:** `develop` @
+`66adaf54`
 
 ## APIs & External Services
 
@@ -14,8 +15,8 @@
   `fitter.sampler` for `extend()`, `save()`, `load_state()`
 - `easyscience.fitting.AvailableMinimizers`, `FitResults`
 - `easyscience.fitting.minimizers.minimizer_bumps` - Its module-level
-  `FitDriver` name is wrapped by `_bumps_constraints.install()` to attach
-  `FitProblem.constraints`
+  `FitDriver` name is wrapped by `_bumps_constraints.install()` to
+  attach `FitProblem.constraints`
 - `easyscience.fitting.minimizers.minimizer_base.MINIMIZER_PARAMETER_PREFIX` -
   Stripped from parameter names in `analysis/bayesian.py`
 - `easyscience.variable.Parameter` / `DescriptorNumber` and
@@ -25,8 +26,8 @@
   `easyscience.io.SerializerComponent` / `SerializerBase` - Base classes
   for `BaseCore`, `BaseCollection`, `DataSet1D`, `CalculatorBase`
 - `easyscience.global_object` - Unique-name registry and undo stack
-- `easyscience.fitting.calculators.interface_factory.InterfaceFactoryTemplate` /
-  `ItemContainer` - `CalculatorFactory` base
+- `easyscience.fitting.calculators.interface_factory.InterfaceFactoryTemplate`
+  / `ItemContainer` - `CalculatorFactory` base
 - Auth: None (Python import)
 
 **Reflectivity Calculators (pluggable via `CalculatorFactory`):**
@@ -69,8 +70,8 @@
 
 **Plotting / Reports:**
 
-- plotly - Corner, trace, distribution plots (`analysis/bayesian.py`) and
-  interactive summary figures; plotly is a hard dependency
+- plotly - Corner, trace, distribution plots (`analysis/bayesian.py`)
+  and interactive summary figures; plotly is a hard dependency
 - matplotlib - `plot.py`, static summary figures, `plot_volume_fraction`
 - xhtml2pdf (`pisa`) - `Summary.save_pdf_summary`; stderr silenced via
   `_silence_pdf_converter`
@@ -136,9 +137,10 @@
 
 - PyPI (`pypi-publish.yml` on tag push, via `pixi run default-build`;
   legacy `python-publish.yml` also present)
-- GitHub Pages via mike (`docs.yml`): `dev` alias from develop, versioned
-  + `latest` on release; a quality dashboard is published by
-  `dashboard.yml` (badgery + radon + interrogate)
+- GitHub Pages via mike (`docs.yml`): `dev` alias from develop,
+  versioned
+  - `latest` on release; a quality dashboard is published by
+    `dashboard.yml` (badgery + radon + interrogate)
 
 **CI Pipeline (`.github/workflows/`, 24 workflows):**
 
@@ -157,8 +159,8 @@
 - `docs.yml`, `dashboard.yml` - site and metrics publishing
 - `security.yml` / `codeql-analysis.yml` / `ossar-analysis.yml` - CodeQL
   and OSSAR scans
-- `release-drafter.yml`, `release-notes.yml`, `release-pr.yml`
-  (develop → master), `backmerge.yml` (master → develop),
+- `release-drafter.yml`, `release-notes.yml`, `release-pr.yml` (develop
+  → master), `backmerge.yml` (master → develop),
   `release-drafter-verify-pr-labels.yml`, `pr-labels.yml`,
   `issues-labels.yml`, `cleanup.yml`
 - `python-ci.yml`, `python-package.yml` - Older pip-based matrices that
 
@@ -1,8 +1,9 @@
 # Technology Stack
 
-**Analysis Date:** 2026-10-15 **Branch analysed:** `develop` @ `66adaf54`
-(tag `v1.7.0-51`; last release `v1.8.0` on 2026-09-18, develop carries
-the unreleased 1.9 work listed under "Unreleased" in `CHANGELOG.md`)
+**Analysis Date:** 2026-10-15 **Branch analysed:** `develop` @
+`66adaf54` (tag `v1.7.0-51`; last release `v1.8.0` on 2026-09-18,
+develop carries the unreleased 1.9 work listed under "Unreleased" in
+`CHANGELOG.md`)
 
 ## Languages
 
@@ -80,7 +81,8 @@ the unreleased 1.9 work listed under "Unreleased" in `CHANGELOG.md`)
   `force-single-line`)
 - pre-commit, prettier (non-Python formatting), pydoclint /
   format-docstring (configured but disabled via `exclude = '\.'`),
-  interrogate (`fail-under = 0`), radon, spdx-headers, validate-pyproject
+  interrogate (`fail-under = 0`), radon, spdx-headers,
+  validate-pyproject
 - copier (`.copier-answers.yml`) - repo scaffold synced from
   `gh:easyscience/templates` (`template_type=lib`)
 - MkDocs Material + mkdocstrings + mkdocs-jupyter + mike (versioned docs
 
@@ -1,6 +1,7 @@
 # Codebase Structure
 
-**Analysis Date:** 2026-10-15 **Branch analysed:** `develop` @ `66adaf54`
+**Analysis Date:** 2026-10-15 **Branch analysed:** `develop` @
+`66adaf54`
 
 ## Directory Layout
 
@@ -164,16 +165,15 @@ Untracked in the working copy (not on `develop`): `.planning/`,
 
 ## Naming Conventions
 
-**Files:** snake_case modules; tests `test_<module>.py`; private module
-`_bumps_constraints.py`.
+**Files:** snake*case modules; tests
+`test*<module>.py`; private module `\_bumps_constraints.py`.
 
 **Classes:** PascalCase (`MultiFitter`, `PreparedFit`, `FitRun`,
 `InequalitySpec`, `PolarizedDataSet`); core import aliased as
 `EasyScienceMultiFitter`; private subclasses prefixed `_`.
 
-**Functions:** snake_case; private helpers `_`-prefixed; `Project`
-exposes `*_at_index` accessors for GUI use
-(`model_data_for_experiment_at_index`).
+**Functions:** snake*case; private helpers
+`*`-prefixed; `Project`exposes`\*\_at_index` accessors for GUI use (`model_data_for_experiment_at_index`).
 
 **Constants:** UPPER_SNAKE (`DEFAULT_MINIMIZER`, `GUIDE_FIELD_ANGLE`,
 `DEFAULT_THETA_M`, `SIGMA_TO_FWHM`, `USER_CONSTRAINT_FLAG`).
@@ -192,9 +192,10 @@ records).
 
 **New constraint kind:**
 
-- Equality: `constraints.py` + persistence in `Project._user_constraints`
-  / `_restore_user_constraints`. Inequality: `inequality_constraints.py`
-  + `Project.add_inequality_constraint`. Tests under `tests/unit/`.
+- Equality: `constraints.py` + persistence in
+  `Project._user_constraints` / `_restore_user_constraints`. Inequality:
+  `inequality_constraints.py`
+  - `Project.add_inequality_constraint`. Tests under `tests/unit/`.
 
 **New calculator backend:**