Contract `chunked-export/v1`

Contract identifier: https://probityai.github.io/agent-evidence-vectors/contract/chunked-export/v1

Corpus: corpora/vectors-chunked-export. Carried in release v0.37.0.

Chunked-export vectors

Cases for chunked-export/v1: an export gate's view when one chunk of a flagged dataset is presented, and the decision the gate must reach. The expected decision and reason for every case are in MANIFEST.json.

Each chunk is reversible on its own, through a documented delete-from-destination capability, so every per-step class is honestly reversible. The chain is not: once enough of the dataset has left, the recipient can reconstruct it, and deleting the chunks no longer undoes the disclosure. A seal that takes the maximum of the per-step labels says reversible while the chain is irreversible. The column headed "steps" is the point of the corpus: six members whose every step is reversible are still denied, and only the composition decides them.

Case	Rule	Chunks out	Steps	Seal	Expected
variant-a-below-threshold	count, k=3	0, 1	reversible	reversible	allow, `reversible_so_far`
variant-a-at-crossing	count, k=3	0, 1, 2	reversible	irreversible	deny, `export_irreversible`
variant-a-final-chunk	count, k=3	0 to 4	reversible	irreversible	deny, `export_irreversible`
variant-a-max-of-labels-seal	count, k=3	0, 1, 2	reversible	reversible	deny, `seal_understates_composition`
threshold-committed-after-first-chunk	count, k=3, committed late	0, 1	reversible	reversible	deny, `threshold_not_precommitted`
sets-three-chunks-no-reconstructing-set	sets {0,1,2} or {3}	0, 1, 4	reversible	reversible	allow, `reversible_so_far`
sets-key-field-chunk-alone	sets {0,1,2} or {3}	3	reversible	irreversible	deny, `export_irreversible`
count-same-three-chunks	count, k=3	0, 1, 4	reversible	irreversible	deny, `export_irreversible`
sets-key-field-max-of-labels-seal	sets {0,1,2} or {3}	3	reversible	reversible	deny, `seal_understates_composition`
step-class-irreversible	count, k=3	0	irreversible	irreversible	deny, `export_irreversible`
contract-id-missing	count, k=3	0, 1	reversible	reversible	deny, `contract_id_missing`
contract-id-unknown	count, k=3	0, 1	reversible	reversible	deny, `contract_id_unknown`

The Variant A decisions (boundary B2) are the ones Mayur Agnihotri posted on agent-evidence#24: a gate reading the maximum of the per-step labels permits at every chunk, and a composition-aware gate permits below the threshold and denies at the crossing chunk and at every chunk after it. The denial is not one-shot. The set cases follow his point on the same comment: reconstruction can depend on which chunks have left (one chunk carrying the key field, an erasure-coded set) rather than on how many, so the general rule is a predicate over the set, not a count.

What a record holds

Every record carries contractId with the value https://probityai.github.io/agent-evidence-vectors/contract/chunked-export/v1, except the two contract cases. It also carries:

chunks: the exported chunks, each with index, leftAt, payloadFile, payloadSha256 and its own stepClass;
exported: the chunk indices in the order they left, the presented chunk last;
reconstruction: the rule the issuer committed to, with committedAt. A count rule names k; a sets rule names minimalSets, each a set of chunk indices that reconstructs the dataset;
seal: the maxClass the seal declares;
dataset: the digest and chunk count of the whole dataset.

The checks

A reader derives the composed class: irreversible when an exported chunk's own step is irreversible, or when the rule holds over the exported chunks (a count rule once k chunks have left, a sets rule once one minimal set has left whole). It then checks in this order and names the first check that fails:

the record carries contractId (contract_id_missing);
contractId is the chunked-export contract (contract_id_unknown);
the rule was committed no later than the first chunk left (threshold_not_precommitted). This follows the pre-fixed completion criterion of agent-evidence-vectors#80;
the seal's maxClass is the composed class (seal_understates_composition). Proposed;
the composed class is reversible (export_irreversible). Proposed.

A record that passes all five is allow with reason reversible_so_far. The sets rule and the order of the seal check and the composition check are Proposed: no published contract states them yet.

What these cases cannot establish

A committed rule makes the seal checkable from the receipts alone and stops the issuer moving the threshold after the fact. It does not show that the rule is right. A k or a minimal set that was derived wrongly yields records that are internally consistent, verify cleanly, and are still wrong, and no reader of these records can tell. How the reconstruction rule is derived for a dataset is out of scope for this corpus.

Run it

python3 vectors-chunked-export/check_vectors.py
python3 vectors-chunked-export/check_vectors.py --verifier "<your verifier>"
GOWORK=off go run ./cmd/aee-verify vectors-chunked-export

The external-verifier contract: <verifier> <case-dir>/record.json --json prints one JSON object carrying decision and reason, and exits 0 for allow and 1 for deny.

Regenerate

python3 vectors-chunked-export/gen_vectors.py

The generator writes every case and MANIFEST.json byte-identically; the corpus tests in tests/ fail on any difference.