Difficulty And Calibration

CoreTex accepts work by measuring improvement over the current parent substrate. The parent and candidate are scored on the same gate and confirm packs, so the threshold is about marginal retrieval gain rather than absolute benchmark score.

The state-advance threshold is:

stateAdvanceThresholdPpm =
  minImprovementPpm + baselineVariancePpm + replayTolerancePpm

The v16 launch profile pins replayTolerancePpm = 250. Current rules v193 use minImprovementPpm = 500, so with no measured variance the live state-advance threshold is 750 ppm. The current baselineParentScorePpm is per live root and must be read from /coretex/status. baselineVariancePpm is present when the current baseline was sampled broadly enough to measure variance. Difficulty terms are policy-controlled and should be read live instead of hardcoded.

Baseline state is tracked per live root. The epoch-start context pins the parent root and baseline manifest hash. Each accepted state advance moves the live root, and the coordinator records the accepted scoreAfterPpm as the effective baseline for that new root. If a root appears without a known baseline, such as after a foreign advance or rotation, submissions return awaiting_baseline_recompute until the recalibrated baseline is installed.

The screener threshold is derived from the same live baseline. It combines:

Signal	Effect
Remaining headroom	Higher parent scores leave less easy gain
Recent noise floor	Raises the gate above measured replay noise
State-advance floor	Keeps screeners tied to the real advance threshold
Probe pass rate	Adds an anti-gaming penalty when weak probes pass too often
Static floor	Operator floor from coordinator config, if set

Under current rules v193, the operator floor sets the live screener threshold to 150 ppm. With the current 750 ppm state-advance threshold, screener passes occupy the 150..749 ppm improvement band, while state advances require the full state-advance gate. Read /coretex/status for the live thresholds before mining or auditing.

Epoch difficulty updates use nextMinImprovementPpm:

Epoch signal	Controller response
More state advances than target	Ramp threshold upward
Zero advances with many quality attempts	Decay threshold
Some quality attempts below target advances	Ease through `under_target_recovery`
Zero advances and zero quality attempts	Drift toward the floor
Major corpus delta	Freeze for one epoch with `major_delta_grace`

A major delta is detected with isMajorDelta(nextEvalHiddenCount, previousEvalHiddenCount, majorDeltaThreshold). The v16 profile pins majorDeltaThreshold = 220. During grace, the threshold is held steady while the baseline is recomputed against the new corpus, frontier, and query-pack context.

Calibration artifacts bind the pieces that matter for replay: corpus root, active frontier root, query-pack policy, baseline score, variance, fixed-pack repeatability, model pins, runtime pins, and profile hash. Corpus evolution also checks that positive eval_hidden qrels still point to available documents before publishing a rotation.