solver options: migrate PHBase-based readers off current_solver_options (#702)

Replace the remaining `self.current_solver_options` reads in
PHBase-based code with `self._effective_solver_options(self._PHIter)`
(or `opt._effective_solver_options(opt._PHIter)` from extensions).
This pulls fwph, aph, and the cross-scenario extension onto the
layered representation alongside PH's own iter0/iterk solves, and
is a real fix beyond just-a-refactor: `current_solver_options`
defaults to `{}` after the phase-2 changes, so user-supplied
`--solver-options "..."` were being silently dropped on these
solve paths. Now they get the full per-iteration fold.

Touched:

* mpisppy/opt/fwph.py (2 callsites)
* mpisppy/opt/aph.py (1 callsite)
* mpisppy/extensions/cross_scen_extension.py (1 callsite)

The migration is mechanical: each line previously passed
`current_solver_options` (a plain dict) and now passes the fold
returned by `_effective_solver_options`. The fold's final layer
is still `current_solver_options` (the back-compat overlay path),
so any Gapper auto-mode mipgap written there still flows through.

xhat_eval and lshaped_bounder (the other current_solver_options
readers) are SPOpt-based, not PHBase-based — they need
`_effective_solver_options` pushed up to SPOpt before they can
migrate. That's a separate follow-up; design doc §6.3 updated to
reflect the new split.

No new tests in this PR: the existing test_aph and the example
runs that exercise fwph and cross_scen catch regressions
(_effective_solver_options is well-tested in
test_solver_options_layers and test_options_reach_solver).

Local: full sweep stays at 229/229 pass (+ 29 expected legacy
deprecation warnings); ruff clean.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: DLWoodruff

doc/designs/solver_options_redesign.md

@@ -841,7 +841,7 @@ Action items (all complete):
 |----------------------------------------------------------|-------------------------------------|----------------------------------------------------------------------------------|---------------|
 | `options["iter0_solver_options"]`, `options["iterk_solver_options"]` (input to PHBase) | **DeprecationWarning fires when non-empty; legacy dicts still folded into `solver_options_layers`** | unchanged target (`solver_options_layers`) | future, TBD   |
 | `PHBase.iter0_solver_options`, `iterk_solver_options` (attribute reads) | **DeprecationWarning fires on every read; both are property shims returning `fold_solver_options_layers(layers, 0|1)`** | use `_effective_solver_options(k)` | future, TBD |
-| `PHBase.current_solver_options` (attribute reads / writes) | active; still used internally as the back-compat dynamic-overrides overlay by several spokes (fwph, aph, xhat_eval, cross_scen, lshaped) | not deprecated in phase 8 — pending those spokes migrating to the layer system | future, TBD |
+| `PHBase.current_solver_options` (attribute reads / writes) | active; fwph, aph, cross_scen_extension now use `_effective_solver_options(k)`; xhat_eval and lshaped_bounder (both SPOpt-based, not PHBase-based) still read `current_solver_options` — pending `_effective_solver_options` being pushed up to SPOpt | future, TBD |
 | `option_string_to_dict`                                  | active                              | unchanged                                                                         | n/a           |
 | `option_dict_to_string`                                  | active                              | unchanged                                                                         | n/a           |
 

mpisppy/extensions/cross_scen_extension.py

@@ -93,7 +93,7 @@ def _check_bound(self):
              and opt.options["tee-rank0-solves"]
         )
         opt.solve_loop(
-                solver_options=opt.current_solver_options,
+                solver_options=opt._effective_solver_options(opt._PHIter),
                 dtiming=opt.options["display_timing"],
                 gripe=True,
                 disable_pyomo_signal_handling=False,

mpisppy/opt/aph.py

@@ -934,7 +934,7 @@ def APH_iterk(self, spcomm):
                 self.dispatch_frac = 1   # to get a decent w for everyone
             logging.debug('pre APH_solve_loop on rank {}'.format(self.cylinder_rank))
             dlist = self.APH_solve_loop(solver_options = \
-                                        self.current_solver_options,
+                                        self._effective_solver_options(self._PHIter),
                                         dtiming=dtiming,
                                         gripe=True,
                                         disable_pyomo_signal_handling=True,

mpisppy/opt/fwph.py

@@ -145,7 +145,7 @@ def fwph_main(self, finalize=True):
             )
             # teeme = True
             self.fwph_solve_loop(
-                mip_solver_options=self.current_solver_options,
+                mip_solver_options=self._effective_solver_options(self._PHIter),
                 dtiming=self.options["display_timing"],
                 tee=teeme,
                 verbose=self.options["verbose"],
@@ -238,7 +238,7 @@ def iterk_loop(self):
                 break
 
             self.fwph_solve_loop(
-                mip_solver_options=self.current_solver_options,
+                mip_solver_options=self._effective_solver_options(self._PHIter),
                 dtiming=dtiming,
                 tee=teeme,
                 verbose=verbose