TACET operator

Runs the TACET log in production. The reference defines the objects; this package fetches, signs, anchors and publishes them.

every hour   tacet-operator run-epoch        drand round → observe surfaces → update map → sign sheet → OTS stamp
every 6 h    tacet-operator refresh-anchors  upgrade OTS proofs; close sheets confirmed in Bitcoin
daily        tacet-operator publish --proofs rebuild featured silence proofs (crovia.seal.v1)

What one epoch does

1. Fetches the first drand round of the hour (chain 8990e7…, pinned in trust_root.json) — the round scheduled at epoch_start, so the sheet does not depend on when the run started. Nothing in the epoch could have existed before that round: lower time bound. The operator refuses to sign a sheet whose round its own verifier would reject.
2. Fetches the surfaces of the featured targets and of a rotating slice of the target list (default 120 per hour, 0.6 s apart, crovia-tacet-observer user agent). Surface = the raw model card …/raw/main/README.md; for gated repositories (401/403) the rendered model page. Collection has a 20-minute wall-clock budget by default (TACET_COLLECTION_BUDGET_S overrides it), so slow or unreachable surfaces cannot occupy the next hourly invocation. Unattempted rotating targets retain their cursor position for the next run.
3. Runs the public predicate crovia.pred.hf-card-training-data 1.0.0 (source, hashed byte-for-byte into every snapshot) on the bytes and signs a snapshot with the observer key. Non-200 responses produce no snapshot: a fetch failure is indeterminate, never absence.
4. Applies forward-only slot transitions: a positive snapshot for an empty slot inserts a disclosure value; two consecutive negatives for a disclosed slot insert a retraction. Every value is asserted by a crovia.seal.v1 signed with the Seal-issuer key (values/<key>.json).
5. Signs the epoch sheet (root, size, snapshots_root, opened beacon, prev_sheet_hash) with the operator key and stamps sheet_hash with OpenTimestamps. When the calendar reaches Bitcoin, refresh-anchors fills closed (block height, block time, proof URL): upper time bound.

The operator is the only writer; all changes of an epoch are applied in one batch, so the sheet's root is the root at epoch_end. Missed hours are back-filled with empty sheets (historical drand round): the chain stays contiguous and those hours contribute no silence.

Each observed run writes state/fetch_log/<epoch>.summary.json with planned, attempted, successful and failed counts, duration, cursor movement and the stop reason. This operational record is not part of the signed protocol objects and does not change verification of existing or future proofs.

Silence proofs

tacet-operator prove mistralai/Mistral-7B-v0.1 --strength 2 -o proof.seal.json
tacet-operator verify proof.seal.json --operator-pubkey <key_hex from trust_root.json>
tacet-operator verify proof.seal.json --offline     # no network: what could not be checked is named in warnings

verify checks signatures, chaining, non-inclusion, snapshots, silence and witnesses from the file. For the two time bounds it does what it can: each drand round's chain and schedule from the sheet, its randomness/signature bytes against the public relays (it does not verify the BLS signature itself), and each Bitcoin anchor by parsing the .ots and comparing with the block header from an explorer. The output lists the per-sheet transcript under beacon and anchors; --offline skips every network call and reports those items as unchecked.

A proof carries every sheet in the range, the delta-encoded non-inclusion path, the negative snapshots with their Merkle inclusion in each epoch's snapshots_root, and the silence block recomputed by the verifier: silence_seconds = sum of the durations of anchored epochs that hold a negative snapshot for the target. Unobserved, unanchored or unreachable hours count zero. The bundle is wrapped in an unmodified crovia.seal.v1.

Keys

Three Ed25519 seeds in state/keys/ (mode 0600), created on first run: operator (signs sheets), observer (signs snapshots), issuer (urn:crovia:seal-issuer:tacet, signs Seals: value assertions and proofs). Public keys are published in trust_root.json.

Install

pip install -e ../reference/python -e <crovia-seal>/reference/python -e .
TACET_STATE=/opt/crovia/tacet/state TACET_PUBLIC=/var/www/registry/data/tacet tacet-operator keys

Tests: pytest -q tests (predicate vectors are real model cards; the epoch test uses a fake network, fake drand and fake OTS).