refactor: unify coords-as-truth handling in add_variables/add_constraints

doc/release_notes.rst

@@ -51,22 +51,29 @@ Most users should keep calling ``model.solve(...)``. If you want more control, y
 **Deprecations**
 
 * ``Solver.solve_problem``, ``Solver.solve_problem_from_model``, and ``Solver.solve_problem_from_file`` still work but emit a ``DeprecationWarning``. Use ``Solver.from_name(...).solve()`` (or simply ``model.solve(...)``) instead. They will be removed in a future release.
+* **Implicit MultiIndex-level projection is deprecated.** Passing an input indexed by a *level* of a stacked-``MultiIndex`` dimension (e.g. per-``period`` bounds onto a ``(period, timestep)`` ``snapshot`` index) emits an ``EvolvingAPIWarning`` — in arithmetic and in ``add_variables`` / ``add_constraints`` — and will raise under the upcoming v1 convention. Project the input onto the dimension explicitly (select with the dimension's level values) to keep current behavior. Affects PyPSA multi-investment models. See Bug Fixes below for details.
 
 **Bug Fixes**
 
+* ``add_variables`` / ``add_constraints``: extends 0.7.0's coords-as-truth rule to ``lower``, ``upper`` and ``mask`` for every bound type and dim order. Pandas ``Series`` / ``DataFrame`` bounds or masks missing a dimension are broadcast to ``coords`` instead of being silently dropped (`#709 <https://github.com/PyPSA/linopy/issues/709>`__); the variable's dimension order always follows ``coords`` (`#706 <https://github.com/PyPSA/linopy/issues/706>`__); bare-tuple coord entries (``coords=[(0, 1, 2)]``) now behave like lists. Mismatched values or extra dims raise ``ValueError`` with a labelled message; sparse-coord masks (formerly a v0.6.3 ``FutureWarning``, #580) raise ``ValueError``, and masks with dims not in the data raise ``ValueError`` instead of ``AssertionError``.
+* Pandas inputs whose index names *levels* of a stacked-``MultiIndex`` ``coords`` dimension are now projected onto that dimension: a level subset broadcasts across the others, the full set aligns element-wise. This fixes PyPSA multi-investment arithmetic (e.g. an expression over a ``(period, timestep)`` ``snapshot`` MultiIndex times a ``period``-indexed weighting). In ``add_variables`` / ``add_constraints`` the input must provide a value for every level combination of the MultiIndex or a ``ValueError`` is raised (the error lists the missing combinations). **Implicit level projections are deprecated**: they emit an ``EvolvingAPIWarning`` everywhere — in arithmetic *and* in ``add_variables`` / ``add_constraints`` — and will raise under the upcoming v1 convention. Project the input onto the dimension explicitly (select with the dimension's level values) to keep current behavior. Aligning the full level set with full coverage stays silent. Strict validation also rejects a ``MultiIndex`` input with *unnamed* levels whose combinations don't match ``coords`` (previously a silent bypass, as such inputs can't be projected by level name).
+* ``add_piecewise_formulation`` now produces a reproducible dimension order in the broadcast breakpoint array. The previous set-based expansion gave a hash-randomized order that varied between processes.
 * SOS constraints on masked variables no longer cause solver-specific failures (Gurobi ``IndexError``, Xpress ``?404 Invalid column number``, LP parse errors, silent set corruption). ``Model.solve()`` and ``Model.to_file()`` now raise a clear ``NotImplementedError`` referring users to `#688 <https://github.com/PyPSA/linopy/issues/688>`__; pass ``reformulate_sos=True`` as a workaround.
 * ``Model.solve(..., reformulate_sos=True)`` now actually reformulates SOS constraints even when the solver supports them natively. Previously it was silently ignored with a warning.
 * Fix Mosek interface to inspect both the basic and IPM solutions and pick the one with the better status, so that an optimal crossover solution is not discarded when IPM terminates with a (near-)Farkas certificate.
 
 **Breaking Changes**
 
+* ``add_variables`` / ``add_constraints``: the v0.6.3 ``mask`` deprecations (#580) are now hard ``ValueError``\ s; an unnamed ``pd.MultiIndex`` in sequence-form ``coords`` raises ``TypeError`` unless paired with ``dims=[i]``. See Bug Fixes above.
+* Sequence-form ``coords`` entries can no longer be ``xarray.DataArray`` objects — they raise ``TypeError``. Pass the underlying index instead: ``variable.indexes[dim]`` (a ``pd.Index``).
 * ``available_solvers`` now lists all *installed* solvers, even ones without a working license. If you used it to decide "can I actually solve with X?", switch to ``linopy.licensed_solvers`` or ``SolverClass.license_status()``.
 * ``Model.solver_model`` and ``Model.solver_name`` are now read-only properties that delegate to ``model.solver``. You can't reassign them (only ``= None`` is allowed, which closes the solver), and ``solver_name`` is ``None`` before the first solve.
 * ``result.solution.primal`` and ``result.solution.dual`` are now ``numpy`` arrays indexed by linopy's integer labels (with ``NaN`` for slots without a value), instead of pandas Series keyed by variable/constraint name. If you accessed them by name, use ``model.variables[name].solution`` (or ``model.constraints[name].dual``) instead.
 * Drop Python 3.10 support. Minimum supported version is now Python 3.11.
 
 **Internal**
 
+* ``linopy.common`` provides two DataArray conversion helpers: ``as_dataarray`` (convert only) and ``broadcast_to_coords`` (convert and broadcast against ``coords``). The latter takes ``strict`` (default ``True``): any mismatch with ``coords`` raises, naming ``label`` in the error; ``strict=False`` passes mismatches through for downstream xarray alignment.
 * Each ``Solver`` subclass now overrides at most three hooks: ``_build_direct`` (build the native model), ``_run_direct`` (run it), and ``_run_file`` (run the solver on an LP/MPS file). File-only solvers (CBC, GLPK, CPLEX, SCIP, Knitro, COPT, MindOpt) only override ``_run_file``.
 * New ``ConstraintLabelIndex`` cached on ``Model.constraints`` (mirrors the existing ``Variables.label_index``); ``ConstraintBase`` gains ``active_labels()`` and a ``range`` property; ``CSRConstraint`` exposes ``coords``.
 * ``linopy.common`` gains ``values_to_lookup_array``; the legacy pandas-based helpers ``series_to_lookup_array`` and ``lookup_vals`` are removed.