stabilizer-qec 2.1.0

An audit of every port against its original's own documented examples, and the gaps it found,
closed. Each port was run on the examples, tutorials and command lines its original documents,
on Stim's own objects as well as this package's, and on Python 3.9 to 3.14 and Windows; what
differed or was missing is fixed below, and what is left is listed in the README and the
inventory (docs/superpowers/notes/2026-10-09-parity-inventory.md). The Python package and the
Rust crate both at 2.1.0. Behaviour changes are under Changed.

Added

• Stim. search_for_undetectable_logical_errors now takes Stim's own steps, and finds Stim's
  faults exactly: the same terms on 3,804 random models, the colour, surface and bivariate
  bicycle codes and BPC72, and Stim's messages where both fail. It is also faster than Stim:
  0.07 s on BPC72 against Stim's 0.25 s (2.0 took 8.1 s), and 0.6 s against 4.0 s on the d = 5
  surface code at limits (6, 6). Limits of (2, 2) go to the graph-like search, as in Stim. The
  CLI's diagram takes --filter_coords, and help <topic> prints Stim's pages (gates,
  formats, commands, indexes, markdown). matchgraph-svg draws a model's undecomposed
  hyperedges.
• PyMatching. The CLI's predict reads b8 by default, as PyMatching's does.
  stabilizer_qec.pymatching.__version__ is "2.4.0".
• sinter. mw_parity_factor and hypergraph_union_find run on this package's MWPF.
• Stim's objects in every port. The qec-util, qLDPC, MQT QECC, MWPF, Deltakit, sinter and
  Relay-BP ports take Stim's own Circuit, DetectorErrorModel and DemInstruction, read
  exactly. Before, they raised errors, and sinter's Fusion Blossom and MWPF decoders silently
  dropped every error of a Stim model.
  MWPF's HeraldedDetectorErrorModel.of, RefCircuit.of and with_circuit take them too, and
  the Tesseract port gives Stim's models back where it was given Stim's.
• stimbposd. stabilizer_qec.stimbposd is stimbposd 0.2.0 whole: BPOSD, BPLSD, the
  sinter decoders, sinter_decoders() (eight variants) and
  detector_error_model_to_check_matrices, bit-identical on ldpc 2.4.1. Use it with
  --custom_decoders_module_function stabilizer_qec.stimbposd:sinter_decoders.
• Relay-BP. ObservableDecoderRunner(parallel=True) and SinterDecoder_RelayBP(parallel=True)
  decode on threads without the GIL: 4.5× serial on the gross code, where 2.0's parallel run
  was slower than serial. Results are bit-identical to relay_bp. With logging=True the runner
  and sinter decoders write relay_logging.out. insert_uniform_academic_circuit_noise takes
  real Stim circuits with REPEAT.
• ldpc. BpOsdDecoder and BpLsdDecoder take ldpc's schedule= and
  random_schedule_seed=. lsd_method and lsd_order can be set after construction,
  OSD_OFF included. input_vector_type="received_vector" on BP+OSD, BP+LSD and BeliefFind
  matches ldpc's decodings and iteration counts. ldpc's exceptions match in type and message,
  and the v1 classes enforce Cython's argument types.
• CUDA-Q QEC real-time decoding.
  • Configuration: decoder_config, multi_decoder_config, CUDA-Q's YAML (read without a new
    dependency), configure_decoders (and _from_file, _from_str), finalize_decoders and
    status codes.
  • Decoding: enqueue_syndromes(id, syndromes, tag) and get_corrections(id, return_size, reset), sliding windows and stim_dem_path. The ticket API is kept.
  • Schemas: decoder_param_schema, registered_decoder_schemas, validate_custom_args,
    JSON Schema export, and the deprecated typed configuration classes.
  • Decoders under CUDA-Q's names: nv-qldpc-decoder, chromobius and nv-fusion-decoder. A
    setting that isn't supported is refused by name.
  • Helpers: dem_sampling (bit for bit with CUDA-Q's CPU sampler), relay_solutions, patch,
    pcm_from_sparse_vec and generate_timelike_sparse_detector_matrix.
  • KernelNotRunWarning for Python @code with registered kernels.
• Tsim. tsim.Circuit is a real subclass of sq.Circuit. It has:
  • Tsim's append (in half-turns), append_from_stim_program_text, from_file, + with Stim's
    circuits and this package's;
  • from_stim_program, stim_circuit, cast_to_stim and without_annotations;
  • CompiledStateProbs, and to_matrix by Tsim's rules;
  • diagrams that label tagged gates, with Tsim's height, width and zoomable HTML wrapper.
• tqec. tqec's call shape: compile_block_graph(g, convention=...).generate_stim_circuit(k=..., noise_model=NoiseModel.uniform_depolarizing(p)) at distance 2k + 1. NoiseModel
  (uniform_depolarizing, si1000) gives tqec's noisy circuits instruction for instruction,
  and BlockGraph.compile takes k= and noise_model=. Block graphs that reuse a tile at
  different times now compile (two CNOTs in a row), and so do pass-through cubes drawn as
  spatial. New: stabilizer_qec.tqec.simulation (start_simulation_using_sinter,
  binary_search_threshold, plots, CSV) on this package's sinter, and
  stabilizer_qec.tqec.interop.pyzx (PyZX graphs in and out, PositionedZX, block_synthesis,
  Pauli webs; PyZX optional). sq.tqec loads on first use.
• Loom. Loom's operations: transversal Hadamard, state injection, auxiliary CNOT, move
  block, move corners, the Y-wall phase gate and rotate block. Its error models
  (CircuitErrorModel, HomogeneousTimeIndependentCEM, HomogeneousTimeDependentCEM,
  AsymmetricDepolarizeCEM) and their noise in the Stim export; the Mimiq and Guppy exporters.
  The repetition, Shor, Steane and five-qubit code factories, with the repetition chain's grow,
  shrink, merge and split. The Executor and TargetLanguage; the Mimiq, CUDA-Q and Guppy
  run-outcome parsers; stim_polygons and the crumble printer; Loom's module paths. Each is
  checked against fixtures recorded from Loom 0.4.0.
• MQT QECC.
  • The analog-information simulators take decoding_method="bposd" again.
  • The colour-code decoder runs as stabilizer-qec mqt.qecc.cc-decoder or
    python -m stabilizer_qec.mqt_qecc.cc_decoder.
  • NoisyDFTStatePrepSimulator runs on this package's qsample at fault-tolerant rates. CNOTs
    are read as (control, target), decoding measures each stabilizer, and a wrong verification
    order is refused. Upstream's simulator never ran.
• PanQEC and qecsim. stabilizer-qec panqec ... and stabilizer-qec qecsim ... run their
  command lines; PanQEC's generated cluster scripts call them, and stabilizer-qec qecsim run
  picks up qecsim extension packages' entry points. qecsim's Blossom V stand-in stays exact past
  512 nodes by matching with Fusion Blossom: the 13×13 run-ftp example takes 40 s instead of
  timing out.
• PECOS. SparseSim.print_stabs(print_destabs=, print_y=), copy, refactor, find_stab,
  run_direct and 'G2'.
• Tesseract. Its binding's behaviour: constructor overloads (TesseractConfig(7)),
  pybind11's enums, the binding's exception types, and output where Tesseract's goes
  (ostream_redirect, Visualizer.write). The decoder's config is read at every decode, as
  Tesseract's is, except the sparsify settings.
• Chromobius. Faults of probability above 1/2 decode as Chromobius's negative-weight
  edges, with its predictions and weights; probability 1 is refused, as Chromobius's weights are
  NaN there. The sinter decoder takes any integer data, and decode_via_files reads short
  files, partial records and other record widths as Chromobius does.
• Deltakit. deltakit.decode carries Deltakit's cloud decoders' names.
• Resource estimates.
  • Azure: the report (status, the jobParams echo, physicalCountsFormatted, reportData),
    format_metric_prefix, format_duration and LogicalCounts.estimate.
    azure_estimate returns an EstimatorResult; a frontier's result["physicalCounts"] is
    its first entry's.
  • Azure: EstimatorError, a ValueError with the QDK's .code and .message, for every
    refusal, in the QDK's order. Unreadable input raises QSharpError with serde's reason and
    column. Both match the QDK on 286 recorded inputs.
  • Azure: LogicalCounts({...}) takes the QDK's dictionary. A qecScheme without a name is a
    custom scheme.
  • Qualtran: stabilizer_qec.estimate.qualtran is a package with Qualtran's fifteen
    submodules, so Qualtran's module paths work. Its UI helpers run without Dash, plotly or
    pandas, with figures as plotly dictionaries. They equal Qualtran 0.7.0 on 448 recorded
    inputs. AlgorithmSummary.from_bloq, NoisyPauliRotation, storage_error,
    GateCounts.to_legacy_t_complexity and TComplexity are also in.
• The exact and stabilizer-rank samplers have a .device.
• qsample. Drawing and plotting raise an ImportError that names the missing optional
  dependency.

Changed

• The coherent and joint samplers complete the circuit's spacetime kernel. One elimination
  over the rotations finds what the local search misses: a logical error at one time with the
  same logical at another, whose amplitudes add.
  • A d = 3 repetition memory with one over-rotation per round was read at the twirl's rate of
    undetected logical errors: 0.00103 against the exact 0.00203, −44σ. It now reads
    0.00206 ± 0.00005.
  • With at most twelve generators the coherent sampler sums the whole class, so its weights
    are exact (exact_weights). Past that, a shot whose faults reach a non-local generator
    sums its elements; num_nonlocal_generators counts those generators.
  • compile_coherent_sampler(max_complete=50_000) bounds the completion. Past it the sampler
    warns that interference between distant faults is left out, and kernel_complete is False.
  • Circuits with an over-rotation after every tick (the README's sweeps, d = 3 to 11) and the
    distillation circuits already had complete local kernels. Their results are unchanged.
• ldpc's BP+OSD now equals ldpc's on every shot checked. OSD weighs ln(1/p) in ldpc's order,
  and macOS's qsort is emulated exactly. On the gross code, 13 of 3,072 shots differed; none do
  now (the README paragraph and tools/gross_ops.py are corrected). The audit's tie hunt went
  from 118 of 16,200 to none, and the QUITS sweep from 4 to none. One BP+LSD shot in 600 still
  differs, from ldpc's cluster merge order, which follows hashed pointers.
• tqec. compile_block_graph(..., observables=None) now means no observables, as in tqec.
  The new default "auto" includes every correlation surface. A CZ flow error names the flow
  as Stim writes it, and gallery.cz takes Stim's sparse flow syntax.
• Tsim. tsim.Circuit's detector sampler reports values as Tsim's does
  (use_detector_reference_sample and use_observable_reference_sample give flips).
  str and repr use Tsim's shorthand. detector_error_model reads T as S, as Tsim's does.
• PECOS. SparseSim.print_stabs() alone prints and returns only the stabilizers, as PECOS
  documents. fault_tolerance_check decodes an ideal round after the faulty one.
• Azure. jobParams echoes the scheme's name as given, and a custom scheme's absent power
  as null.

Fixed

• Stim.
  • OBSERVABLE_INCLUDE targets print in the order written (a Pauli before a record).
  • explain_detector_error_model_errors(dem_filter=) lists in Stim's order.
  • A search that finds no logical error raises Stim's message with its warnings.
  • A negative repetition count on a circuit or model raises Stim's TypeError.
• Tsim. Two adjacent identical I[R_PAULI(...)] lines were fused into one that didn't
  parse.
• PECOS 0.2.0's own bugs. Its phenomenological error models (DepolarGen, XGen,
  ZGen, XZGen), mixed two-qubit error sets on NumPy 2, TimingRunner.total_time and
  run_gates, fault_tolerance_check on the shipped codes, instruction plots on networkx 3,
  and the Python simulator's copy and refactor. 'init |-i>' prepares |−i>, and Y prints
  with its sign.
• qecsim. Centre-slice labels lim=(0.2, 0.8, 0.0) work under NumPy 2, and its
  missing-argument message under click 8.2.
• PanQEC and qecsim. --version names panqec and qecsim again.
• Relay-BP. Check matrices with stored zeros or even entries decode as relay_bp's do.
• Tesseract. The two-pass decoder on an annotated model ("DEM error index out of range"),
  repeated detection events (a panic), merging zero-probability errors ("bad argument 'nan'") and
  beam climbing with a negative beam now give Tesseract's answers.
• Python 3.9 and 3.10, and Windows. Loom's operations ran only on 3.11+ (zip(strict=));
  they now run everywhere. The tests read Windows' line endings and paths, Stim's Windows help
  pages and click 8.1, and skip a port's tests where its Python or extras are missing.

Not ported

These remain, each listed in the README and the inventory:

• tqec's Hadamard pipes, spatial junction cubes and Y cubes, and its plaquette templates and
  detector search.
• PyMatching's animate.
• Tsim's PyZX diagrams and ZX graphs, its bit-for-bit (JAX) random numbers, and to_matrix
  with measurements.
• CUDA-Q QEC's dem_chunks, expand_dem_chunks and trt_decoder.
• The QDK's parameter classes (their dictionaries are accepted), and Qualtran's Dash layout.
• The coherent sampler's truncation past twelve generators. On a d = 3 surface-code memory over
  three rounds (fourteen generators) it moves the silent logical rate from 2.0's 0.00100 to
  0.00161 ± 0.00013, against the exact 0.00258. Part of the interference between rounds is
  still left out.
• Chromobius's predictions differ on some shots, always at the same matching weight. Its
  lifting depends on the order of the matched edges, and this package's matcher does not list
  them in PyMatching's order. Handed PyMatching's edges, the lifting equals Chromobius's on all
  but 1 of about 18,500 shots checked. The weights are bit for bit.
• Fusion Blossom's helper.bottle, a vendored copy of the Bottle web framework (the
  visualiser is served by the standard library). Tesseract and Chromobius have no command
  line, and the Tesseract port's A* decoder takes at most 64 observables.
• QUITS's distance search uses more memory and time than Stim's: 456 MB and 8.7 s against
  139 MB and 1.6 s on [[72, 8, 8]].

Install: pip install stabilizer-qec==2.1.0 (Python), stabilizer_qec = "2.1" (Rust).