fishersketch 0.2.0

Vocabulary-scale output-error task signatures: a portable .fsig registry + a regime diagnostic for transfer source selection

FisherSketch

Fingerprint a task in 192 KB — then compare, deduplicate, diagnose, and route across a registry of tasks, without re-running the model and without sharing the data. A FisherSketch signature (.fsig) is an aggregate sketch of a task's training-error geometry — a pooled sum over the whole dataset, with no per-example records — so you can exchange a task fingerprint where you could never share the dataset (see Privacy scope below for exactly what it does and doesn't hide). And it works at vocabulary scale (K ≈ 128k) — where the classical label-aware transferability scores (LEEP, LogME, H-Score) cannot run at all: the exact object is a per-task K×K error covariance (~6 TB across 100 tasks); the 192 KB sketch is a ~1,510× reduction (LEEP's joint table alone is 128k² ≈ 10¹⁰ entries; LogME / H-Score degenerate at K≫N).

For teams maintaining many fine-tuning datasets or task variants on a shared model — dedup near-identical tasks, find related ones, diagnose where transfer signal lives, and route to the best source — with no model and no raw data on hand. Straight from the shell:

python -m fishersketch inspect sigs/    # what's in a registry of .fsig fingerprints (no model needed)

Share fingerprints, not data. This is the differentiator: a registry of .fsig files carries a corpus's update geometry without the corpus — something an embedding-and-cosine workflow can't cleanly give you.

What it is — and isn't. It is a fixed-model task registry + a regime diagnostic + the only label-aware task signature that runs at vocabulary scale; mechanically, the signature is the task's output-error (Fisher) update geometry, sketched in one streaming pass. It is not a general transfer ranker — when activations are informative a cheap class-conditional centroid can match it on source-ranking, and the activation×error coupling is a ranking wash. Its edge is feasibility where nothing else runs, the privacy-preserving registry, and the activation-dark floor: where a verbalizer/format shift leaves representation methods at chance (provably blind — Theorem 3.2), the error geometry still recovers transfer (≈3× over random).

Reference: Sweeney, The Geometry of Updates: Fisher Alignment at Vocabulary Scale, ICML 2026 — arXiv:2606.27242 (PMLR v306, to appear).

When to reach for this (and when not)

Two questions decide whether any transferability method works for shared-vocabulary LLM source selection — and every prior method fails one of them:

1. Does it see the error geometry, not just activations? Representation-similarity metrics — CKA, RSA, SVCCA (and the activation-only second moment Scov(Ma)) — read only the probe activations. They are provably blind to the head update: identical activations can hide orthogonal updates (Theorem 3.2). In the activation-dark regime — e.g. a verbalizer shift, where you change only the answer token so the answer-position activation literally cannot move — they collapse to random.

2. Does it scale to vocabulary K ≈ 128k? Classical transferability scores — LEEP, LogME, H-Score — are label-aware, so they don't collapse in activation-dark. But they hit a vocabulary-scale wall: LogME and H-Score degenerate when K ≫ N (you can't estimate per-class structure over 128k classes from a probe of a few hundred samples), and LEEP hits a K² memory wall (its 128k×128k joint label table ≈ 10¹⁰ entries). They can't run where you operate.

FisherSketch is the one of these methods that answers yes to both — it scores the joint (activation, error) update geometry and sketches it in one streaming pass at vocabulary scale. Measured on Llama-3.1-8B, it has the best worst-case across regimes:

Method	Natural shift	Verbalizer (activation-dark)	Worst case
Scov(Ma) / CKA-family	46.3%	20.0% (= random)	20.0%
Scov(Γe) error-only	41.3%	72.2%	41.3%
FisherSketch	45.7%	66.7%	45.7%
LogME / H-Score	—	—	degenerate (K≫N)
LEEP	—	—	K² memory wall

The cheap competitive option is error-only Scov(Γe) — it scales and sees the errors, and is in fact better than the joint in the activation-dark column (72.2% vs 66.7%), but it has a worse worst-case (41.3%) because it ignores the activation geometry that helps under natural shift. FisherSketch's edge here is feasibility and the activation-dark floor, not a per-regime ranking win: it is the one of these that runs at K≈128k and sees the error geometry, so it is never catastrophic across regimes (the worst-case column). The activation×error coupling ρ itself adds no measured ranking value — regime() reports coupling: engaged vs ~squashed, and when squashed the joint simply tracks the error marginal; within a single regime a specialized method (error-only when activations are dark, a class-conditional centroid when they're informative) can out-rank the joint on ranking. That comparison flips on relatedness / retrieval — the registry's main job: the FisherSketch fingerprint edges a plain activation centroid by +0.038 micro-accuracy (m=4096, paired p<0.001) on the paper's 700-task NaturalInstructions retrieval. A modest, no-label margin — when task labels are available a learned linear probe beats the fingerprint on the same retrieval, so reach for this where you can't train a probe. Measure on your own data. The bundled fishersketch.evaluation baselines (cka, logme, hscore, leep, and the Scov marginals) let you reproduce each collapse on your own data. Call scalability_report(d, n, K) to surface the K≫N / K² wall directly — a raw logme() / hscore() call below its class ceiling returns a plausible-but-meaningless finite value rather than erroring.

Decision flow: shared output basis? → activations activation-dark? → stream FisherSketch → rank sources + audit ρ. Best fit: shared-vocab LLM families and scientific string domains (SMILES, protein, genomic tokens). Out of scope: heterogeneous outputs — use the full-network sketch (FisherNetwork). It is checkpoint-conditional (Fisher at one checkpoint) and one signal among many — pair it with coverage / fairness / safety before automating.

What's in this build

The full validated pipeline behind the paper's numbers:

• Factored Random-Maclaurin features for the degree-2 product kernel (a·a')²(e·e')², O(m(d+K)) per sample.
• SRHT projections for the K-dimensional error, auto-enabled at vocabulary scale (dim_e ≥ srht_threshold, default 65536) via a Walsh–Hadamard transform — O(K log K) instead of O(mK). numba-accelerated when the fast extra is installed, with a vectorized numpy fallback otherwise.
• Split-half (A/B) estimation, U-statistic diagonal correction, positivity clamping, the χ/ρ coupling decomposition, and empirical-Bayes ρ-shrinkage (the robust vocabulary-scale ranking estimator).

Install

pip install fishersketch              # core: numpy + torch
pip install "fishersketch[fast]"      # + numba (JIT-accelerated CPU SRHT; optional)
pip install "fishersketch[examples]"  # + transformers (only the AI4Sci example + HF benchmarks)

From a clone, for development: pip install -e ".[test]" (adds pytest).

torch is required — it is the array backend and the GPU engine. It runs on CPU by default (device="cpu"); pass device="cuda" or "mps" to accelerate. numba is optional: without it the SRHT Walsh–Hadamard transform falls back to a vectorized numpy implementation (identical results, slower at vocabulary scale).

First result in 60 seconds (no model):

pip install fishersketch
python -m fishersketch.evaluation                 # activation-dark surrogate: error-geometry 0.83 vs activation-only 0.17
# from a clone, the full registry walkthrough:
python examples/00_atlas_registry_quickstart.py   # build -> save .fsig -> reload registry -> diagnose -> recommend

Examples are tagged: 00 / 02 / 04 run as-is; 01 / 03 / 05 need a torch model.

Quickstart (copy-paste runnable)

No model needed — fishersketch.demo ships tiny synthetic streams so this block runs as-is:

from fishersketch import FisherAtlas
from fishersketch.demo import make_toy_streams

# {name: (a, e)} with a:(n, d) activations and e:(n, K) errors (= softmax(logits) - onehot(y)).
# The toy tasks share an activation backbone (activation-dark) and split into two error groups,
# so there is a real ranking to recover.
streams = make_toy_streams()

atlas = FisherAtlas.from_streams(streams, sketch_dim=2048, seed=0)
rec = atlas.recommend("task0")          # which other task best transfers to task0?
print(rec.explain())                    # best source, score, gap to runner-up, confidence

With no model at all, python -m fishersketch.evaluation runs the activation-dark surrogate — a synthetic check that the error geometry recovers transfer (~0.83 top-1) where activation-only sits near chance (~0.17).

Runnable scripts are in examples/: a model-free atlas → registry → diagnostic quickstart (00, no assets needed), source selection on a model (01), signature persistence (02), the full network + certificate (03), evaluating against the baselines on your own data (04), and AI-for-science masked-LM streams (05). 00 / 02 / 04 run as-is; 01 / 03 / 05 need a torch model.

One call, straight from a model

If you have a torch model and per-domain dataloaders, skip the manual extraction entirely:

from fishersketch import recommend_sources

rec = recommend_sources(
    model,
    target="my_domain",
    candidates=["wiki", "code", "legal"],
    data={...},                         # {name: dataloader} yielding (inputs, labels)
    head=model.lm_head,                 # the head whose Fisher alignment you want
    task="lm",                          # "lm" | "classification"
)
print(rec.best.name, "->", rec.explain())

recommend_sources hooks the head, extracts (activation, error) for each domain in one streaming pass, builds the atlas, and returns a Recommendation (best source, per-source scores, the gap to the runner-up, and a confidence flag).

Reading the recommendation

recommend() defaults to method="auto": it first reads the regime — which geometry actually carries the transfer signal — and then scores by that geometry rather than blindly returning the joint. rec.explain() prints the pick, the regime it followed, and the signals that tell you whether to trust it (below, the bundled make_toy_streams() demo — an activation-dark task set, at sketch_dim=2048, seed=0):

Recommended source for 'task0': task1
  regime: activation-dark -> auto-scored by 'error_only'  (activation 0.005, error 0.955, coupling alpha 0.00)
  task1            A_F=+1.111  (|src|/|tgt|=1.01)  <- best
  task3            A_F=+0.168  (|src|/|tgt|=0.99)
  task2            A_F=+0.159  (|src|/|tgt|=0.99)
  verdict: LIKELY worth it  (#1-vs-#2 gap 2.1 cand-sigma; vs random +1.4 sigma; winner se(logrho)=0.04)
  baselines: activation-only picks 'task2'; error-only agrees
  note: activation geometry is ~constant across sources (activation-dark / verbalizer regime -- error geometry is doing the work)
  coupling: ~squashed (alpha=0.00) -- at this sample count the ranking tracks the marginal product; collect more samples to engage the coupling term

This is the representative case: the coupling reads ~squashed (engaging it needs hundreds of samples per task), and the activation-dark note shows the error geometry carrying the signal — the regime FisherSketch is built for.

The score is the symmetric A_F (the directionless similarity); recommend(..., directed=True) opts into the directed coefficient B = A_F·|i|/|j| (shown as B=…), whose |i|/|j| norm ratio is data-dependent. The regime: line is the key control. Each geometry gets an engagement number (the symmetric analog of the coupling's α); a degenerate one can't rank, so auto drops it:

Regime (atlas.regime())	What it means	What auto scores by
coupled	activation and error informative, coupling engaged	the joint fisher score
separable	both informative but coupling squashed (joint tracks the marginal product)	fisher (still orients the ranking)
activation-dark	activations don't separate the tasks (verbalizer shift, small-scale SMILES)	error_only — the detector defers the joint where the activation factor is below engagement
error-flat	errors ~uniform across tasks	activation_only
no-signal	neither geometry separates the tasks	fisher, but treat any pick as low-confidence

The remaining lines refine the trust call:

Line	What it tells you	What to do
coupling: engaged (alpha≥0.15)	both geometries are informative and not independent — the score reflects both, not a single marginal	the pick is supported by both geometries (subject to the verdict)
coupling: ~squashed (alpha≈0)	the joint tracks the marginal product at this sample count — the coupling is below engagement	gather more samples (~256+/domain) to engage the coupling
power: LOW (shown when present)	the winning pair is statistically noisy	gather more samples before trusting it
verdict: NO source clears the bar	nothing is strongly aligned	don't transfer
baselines:	the free cross-check	error-only agrees → solid ground; if the joint disagrees with both marginals, treat the pick with caution — the cheap marginal is the safer signal

The verdict is gated on the coupling: it will never say CONFIDENT when the coupling is squashed (a low per-pair SE can't rescue a globally-uninformative coupling).

Scale to vocabulary (the real regime)

For an LLM head you build the atlas incrementally and let SRHT auto-engage:

# d = hidden size entering the head; K = vocab/output size.
atlas = FisherAtlas(dim_a=4096, dim_e=128256, sketch_dim=4096, device="cpu")

for name, (acts, errs) in task_streams.items():     # acts:(n, d), errs:(n, K)
    atlas.add_task(name, acts, errs)                # error = softmax(logits) - onehot(y)

names, A = atlas.alignment(shrinkage=True)          # full T×T alignment matrix
diag = atlas.diagnostics()        # S_ae, S_a, S_e, chi, rho, rho_shrunk, fisher_shrunk, ...
print("SRHT active:", atlas.uses_srht)              # auto-on once dim_e >= srht_threshold

AI-for-science (scientific foundation models)

Scientific foundation models are first-class. Masked-LM encoders — ESM-2 (proteins), ChemBERTa (molecules), DNABERT / Nucleotide Transformer (genomics) — go through fishersketch.extract.mlm_streams, which masks tokens and captures the MLM head-Fisher signal (a, e) for you; causal scientific LMs (ProtGPT2, ProGen) use the same recommend_sources(..., task="lm") path as any LM. See examples/05_ai4sci_masked_lm.py (and benchmarks/sci_data.py / moleculenet_data.py for UniProt / MoleculeNet / genomic loaders to bring your own corpora).

from fishersketch.extract import mlm_streams
streams = mlm_streams(esm_model, esm_tokenizer, {name: [seq, ...] for name in corpora})
atlas = fishersketch.FisherAtlas.from_streams(streams)
print(atlas.regime().explain())     # which geometry carries the signal on YOUR data?
rec = atlas.recommend(target)       # ranks sources by the geometry the diagnostic trusts

The honest value here is diagnosis, not a magic ranker. The regime() readout tells you where transfer signal lives for your model + data — and that answer is informative: a domain-native encoder (e.g. ESM) carries family structure in its activations while the per-token errors are near-flat (all proteins share one amino-acid alphabet), so the detector routes to the activation geometry — a distinction a token-frequency baseline cannot make. The flip side, stated plainly: on a diffuse general LM applied to scientific strings the per-token error can be dominated by the token-frequency term (high next-token entropy → the −onehot(y) term dominates), and the detector will tell you so (error-flat / squashed coupling) rather than quietly hand you token statistics dressed as geometry. Use a domain-native scientific FM, and read the diagnostic before trusting any ranking.

Persist & share signatures (.fsig)

Sketch each domain once, save it, and compare new domains against the saved set later — no need to re-run the source models. A signature is the six unnormalized {A,B}×{ae,a,e} accumulators (192 KB at m=4096, 48 KB at m=1024); reloading and replaying them reproduces the live atlas's fisher_shrunk / directed_fisher bit-exactly. A .fsig is a versioned FSIG binary (magic + JSON header + float64 payload) — load it with FisherSignature.load(path) or SignatureStore.from_dir(dir), not np.load.

from fishersketch import FisherAtlas, SignatureStore

# Producer: sketch domains (maybe on different machines) and write one .fsig each.
FisherAtlas.from_streams(streams, sketch_dim=4096, seed=0).save_signatures("sigs/")

# Consumer: load the open set and score it (shrinkage is set-dependent, so adding a
# signature can move other pairs — by design).
store = SignatureStore.from_dir("sigs/")
print(store.recommend("my_target").explain())
names, A = store.alignment()

A SignatureSpec.key() fingerprint hard-gates every comparison: signatures built in different projection bases (seed, dims, sketch method, augment_bias, …) raise IncompatibleSignatureError naming the offending field, rather than returning silent garbage. compare(sig_i, sig_j) scores a single pair; sig_a + sig_b merges two shards of the same domain collected separately.

From the shell. No script needed — python -m fishersketch works over a directory of .fsig:

python -m fishersketch inspect  sigs/            # table: tasks, samples, grad-norm, model, basis key
python -m fishersketch diagnose sigs/            # which geometry carries the signal (regime)
python -m fishersketch dedup    sigs/            # near-duplicate task pairs (self-normalized cosine)
python -m fishersketch nearest  sigs/ my_task    # the tasks most related to my_task
python -m fishersketch score    sigs/ my_target  # rank sources (symmetric A_F; --directed opts in to |i|/|j|)

inspect/dedup/nearest read only metadata + the joint vectors (no model); diagnose/score replay into the estimator. In Python, FisherRegistry aliases SignatureStore, and score_registry(dir_or_store, target) is the one-call score. Each subcommand has its own --help (e.g. python -m fishersketch score --help): score --method/--directed/--candidates, dedup --threshold, nearest -k.

Privacy scope — what a .fsig does and doesn't hide

A .fsig lets you exchange a task fingerprint without shipping the dataset, but be precise about the guarantee — it is aggregation-based obfuscation, not differential privacy (no ε, no formal proof). Against an adversary holding the .fsig, the published projection seed, and the model:

• Obscured (when many samples are pooled): the per-example activations and labels, and the signed label-mean direction. The degree-2 sketch is sign-blind and the signature is a pooled sum, so individual records and the update's sign aren't directly readable. This weakens as the pool shrinks — at N=1 the sum is the single example, and given the model a small-N label set can be brute-forced.
• Recoverable by construction: the aggregate second-moment (activation/error) covariance — that is literally the statistic the sketch computes, so anyone with the .fsig can read it.

Pool a meaningful number of samples per task (the same n ≳ 32 the estimator wants for a stable score), and treat a .fsig as "doesn't carry the raw corpus," not as a cryptographic guarantee. For a formal bound, add noise under a DP mechanism upstream — FisherSketch does not.

Beyond the head: multi-layer transfer (FisherNetwork)

The head estimator scores the last layer's update. FisherNetwork is the real Full FisherSketch (Theorem O.18): it owns forward/backward, hooks every tracked nn.Linear, and sketches the concatenated per-layer Kronecker gradient g = [a₀⊗δ₁; …; a_{L-1}⊗δ_L]. The exact kernel sums inside the square — (g·g')² = (Σ_l (a_l·a_l')(δ_l·δ_l'))² — so it is cross-layer aware, unlike the per-layer "block" proxy that drops the interaction.

from fishersketch import FisherNetwork

net = FisherNetwork(model, layers="auto", sketch_dim=4096)   # all nn.Linear
with net.capture():
    for name, loader in data.items():
        net.begin_task(name)
        for inputs, labels in loader:
            model.zero_grad()
            loss_fn(model(inputs), labels).backward()        # your loss
        net.end_task()

names, A = net.alignment(mode="full")    # "full" | "block" | "off" (cross-layer only)
print(net.recommend("my_target").explain())
print(net.certificate())                 # is the cheap block answer trustworthy here?

The one-pass decomposition is A_full = A_blk + A_off (block + cross-layer interaction, disjoint support). certificate() returns a profile cosine and a certified bound |cos_full − cos_blk| ≤ (1−c_r) + w_off·|cos_off − cos_blk| — it tells you when the cheap coupling-blind block answer can be trusted (the paper sees c_r ≥ 0.90). Full-network signatures persist as estimator="full" .fsig and replay bit-exactly, exactly like the head. v1 tracks nn.Linear only (incl. tied lm_head); disable activation checkpointing on tracked layers.

Power-user API

Most users only need FisherAtlas (or FisherNetwork). The validated estimators and the lower-level sketchers live in fishersketch.backend:

from fishersketch.backend import (
    FisherSketchGPU,            # the torch engine FisherAtlas drives
    FisherSketch,              # numpy CPU estimator
    SeparableLayerProxyGPU,    # the coupling-blind per-layer proxy (Σ_l S_a·S_e)
)

SeparableLayerProxyGPU (formerly BlockDiagonalProxyGPU, kept one release as a deprecated alias) registers hooks on nn.Linear modules and sums the matched per-layer Scov(Mₐ)·Scov(Γₑ) products. It is the coupling-blind proxy: it drops both within-layer a–e coupling and cross-layer interaction. For the coupling-aware multi-layer estimator use FisherNetwork; for the coupling-aware head, FisherAtlas.

Estimator semantics & caveats

• alignment() / rank_sources() return a RANKING score (higher = a better predicted transfer source; the diagonal is ~1). It is the U-statistic estimate of the head Fisher alignment — well-calibrated to the population value (the cosine of the task mean embeddings) — but, being an unbiased ratio rather than a Cauchy–Schwarz-bounded cosine, it can slightly exceed 1 for highly similar tasks (an overshoot, like an unbiased correlation). It is intentionally not clipped to [0, 1]: clipping flattens the graded values into a constant tie and destroys the ranking in exactly the shared-error / activation-dark regime this library targets. Orthogonal tasks read ~0. The default shrinkage=True adds empirical-Bayes ρ-shrinkage (ρ capped at the separability ceiling 1 to bound the near-orthogonal 0/0 ratio — ranking-safe, slightly compresses genuine super-coupling); shrinkage=False is the raw joint cosine — noisier, and positively biased on near-orthogonal pairs.
• It is not the literal Algorithm-1 pooled-μ cosine. It is the split-half (A/B) estimator with a per-split U-statistic diagonal correction and positivity clamping (paper Sec 5.3 / App B); both are unbiased for the same population.
• Input scale. The estimator is invariant to rescaling the errors, but it assumes the documented input e = softmax(logits) − onehot(y) (‖e‖² ≈ 1). Feed the raw head error, not a normalized or per-sample-rescaled version (per-sample normalization changes the kernel). NaN/inf inputs are rejected; each task needs ≥ 2 samples (≥ 4 recommended) for the A/B split.
• Backends. FisherAtlas always uses the torch FisherSketchGPU. The numpy FisherSketch is a lighter CPU reference with a less numerically-stable χ/ρ path; the two are not bit-identical. On MPS, accumulators fall back to float32 (96 KB per-task state vs. 192 KB), slightly reducing precision at large sample counts.
• Evidence — what is checked where. Method: the kernel identities, sketch unbiasedness, SRHT, and the non-identifiability theorem (Thm 3.2) are unit-tested in tests/. Demonstration: python -m fishersketch.evaluation runs the activation-dark surrogate and prints error-geometry 0.83 vs activation-only 0.17 — synthetic, no model. Paper: the real-model numbers — the ~72% activation-dark top-1 and the ~1,510× memory figure — are from Llama-3.1-8B with real activation/error streams; they are not reproducible from this repo, which ships no weights. Bring your own streams to fishersketch.evaluation.run_eval. This is an early (0.2.0) release.

Troubleshooting

Symptom	Cause	Fix
IncompatibleSignatureError on compare/add	signatures built in different bases (seed, dims, sketch method, augment_bias)	re-sketch with matching settings; a .fsig compares only within one basis and one base model
SuspiciousErrorScaleWarning	you passed raw logits, probabilities, or per-sample-normalized errors	pass e = softmax(logits) − onehot(y), or use fishersketch.extract
a score above 1 (e.g. compare returns 2.6)	expected — the alignment is an unbiased U-statistic ratio, not a clipped cosine	use it for ranking/relatedness; the order is what's calibrated, not the magnitude
ScalabilityWallError, or logme()/hscore() returning a meaningless finite number	K ≫ N — the classical baseline can't estimate per-class structure	call scalability_report(d, n, K) to see the wall; this is the regime FisherSketch is for
np.load fails on a .fsig	.fsig is a versioned FSIG binary, not an npz	load with FisherSignature.load(path) or SignatureStore.from_dir(dir)
adding a signature moved other pairs' scores	the empirical-Bayes shrinkage is set-dependent, by design	for a pair-invariant score use shrinkage=False, or nearest/duplicates (already pair-invariant)
SignatureStore(path) raises TypeError	the constructor takes a SignatureSpec, not a path	use SignatureStore.from_dir(path)

API at a glance

FisherAtlas	stream tasks (from_streams / from_model / add_task) → alignment / rank_sources / recommend / regime / diagnostics / signature / save_signatures
SignatureStore (alias FisherRegistry)	open-set registry: from_dir / add → summary / regime / rank_sources / recommend / nearest / duplicates
FisherSignature	portable .fsig artifact: save / load, + merges shards, to_joint → 16 KB .fsigj
compare(a, b) / align(sigs)	pairwise / cohort alignment from signatures
recommend_sources(model, target, candidates, data)	one call from a live model → Recommendation
score_registry(dir_or_store, target)	one call from a saved registry, no model → Recommendation
classify_regime / RegimeDiagnostic	which geometry carries the transfer signal
FisherNetwork	multi-layer (full-network) variant
extract.head_streams / mlm_streams	model → (activation, error) streams
evaluation / baselines	eval harness + CKA / LEEP / LogME / H-Score / centroid
python -m fishersketch	CLI: inspect / diagnose / dedup / nearest / score

Inline type hints ship via py.typed.

Status

0.2.0 — full pipeline (validated against exact Fisher in tests/) plus the adoption layer: one-call recommend_sources, the model→signals extractor, and portable .fsig signatures with bit-exact replay. An early (pre-1.0) release; the public API may still change before 1.0. Licensed under Apache-2.0 (see LICENSE/NOTICE); Copyright 2026 Sideplane AI.