Restores the PeriodicBlockStepper safeguard dropped in 8e1feff, for all
FixedPatchStepper levels: both G buffers, halo pairs and boundary columns
of every level are compared with cuda.mem_get_info() before the stream,
any module or any buffer exists, raising MemoryError('level buffers exceed
free device memory'). Transfer tables are not counted (lower bound).
Tests: the single-level MemoryError case is back beside the param-layout
check (no stream, no allocation); host test_single_level covers depth 1
and depth 2 (no stream, build or allocation) and the wait failure after a
good step (count stays 1). Driver-mocking fixtures report ample free memory.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The second owner of one blocked level goes. Its capability is the
zero-refinement FixedPatchStepper added in f764d68/985db14 (periodic SRT
level, stationary passive circles, shifted storage, NaN spare, single wait),
which matched it array for array on GPU at 1318fc2 (3 splits x +-circle x
shifted/unshifted) and passes the host lifecycle and fault contracts.
API change for callers:
PeriodicBlockStepper(cfg, BlockLayout2D.build(ny, nx, by, bx), context=c, objects=o)
-> FixedPatchStepper(cfg, context=c, refinements=[], level_blocks=[(by, bx)],
level_objects=[tuple(o)])
download() returns a 1-tuple; static-circle tables are
_level_boundaries[0].tables (was .boundary); no free-memory preflight.
- lbm/block_stepper.py deleted; MAX_GRID_DIM lives in refinement_stepper.
- tests/validation/multigrid/test_block_stepper.py: same frozen GPU gates
(split identity, FP64 oracle, circle across seams) and pre-CUDA rejection
cases on the single level; the old-vs-new bitwise test is retired with the
old class (its result is the 1318fc2 record).
- tests/unit/test_block_step_sync.py folded into test_single_level.py
(step(n) vs n x step(1) roles and one wait, step(0), mid-batch launch
failure), which also gains bad-state rejection before upload, download
failure and activation-failure retry on close.
- test_shifted_storage and test_raw_exchange_gpu use the single level; the
raw-exchange reference feeds the AMR Jet column and raw ledger through the
root level boundary instead of patching a private kernel field.
- Pinned historical runners (taylor_green/run_case.py, run_jet_circle_cv.py)
are unchanged: they only run on trees that still ship PeriodicBlockStepper.
No alias.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Fault injection with the existing host fakes for FixedPatchStepper(
refinements=[]): an initialize upload failure, a BlockHaloCopy,
BlockCurvedBoundary or BlockStep launch failure, and a failing final
stream wait each raise, leave the instance failed (step/download refused)
and keep the completed step count; a failed launch never reaches the wait.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Review follow-ups for S1 (f764d68):
- a single level starts its spare buffer NaN, as PeriodicBlockStepper does,
so stale halos cannot hide (multilevel initialization unchanged);
- projected explosion is rejected for a single level;
- new tests/unit/test_single_level.py: NaN spare after initialize, per-step
launch order halo -> BFL (circles only) -> BlockStep with a null kind and
one wait per step(n), circle solids excluded from the state mask;
- the GPU bitwise comparison also covers shifted storage.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
