Deterministic Enforcement Contract — PreFlight v1.01

PreFlight — Deterministic Upstream Data Ingestion Gate

pf_v1.01 evaluates a fixed sequence of structural checks; this contract defines each check and its verdict.

Contract Statement

PreFlight v1.01 evaluates tabular datasets through seven fixed tests, in fixed order, with mechanical verdict reduction. No configuration changes behavior. No logic adapts, learns, or scores. Identical input produces an identical report — byte-identical, hash-verifiable.

The Seven Tests — fixed execution order

1. Schema Structural Integrity — FAIL class. Column-count mismatch, structural drift, unstable delimiter interpretation.
2. Row Iteration Viability — FAIL class. Corrupted record boundaries, malformed termination.
3. Numeric Coercibility — FAIL class. Non-coercible values in unambiguous numeric columns.
4. Multiple Valid Representations — WARN class. Fields holding multiple valid encodings (e.g., mixed date formats).
5. High Null Density Columns — WARN class. Predominantly null fields.
6. Malformed or Truncated Rows — FAIL class. Incomplete records, broken continuity.
7. Text Encoding Integrity — FAIL class. Non-decodable byte sequences; evidence includes the byte offset. Encoding damage is FAIL-class; only elevated rates of low-severity markers reduce to WARN.

Order is immutable. Every test runs on every evaluation.

Evaluability Conditions

Evaluation requires ≥ 30 logical data rows after the header, ≥ 2 columns, and ≥ 20 non-empty logical rows. Below these thresholds the verdict is ANALYSIS_INCOMPLETE — insufficient evidence never reduces to PASS.

Verdict Reduction — mechanical, complete

Any FAIL → FAIL. Else any WARN → WARN. Else any ANALYSIS_INCOMPLETE → ANALYSIS_INCOMPLETE. Else PASS. No weighting, no scoring, no interpretive logic. A test that cannot run cannot produce a PASS.

Reproducibility Guarantee

Every report carries two SHA-256 hashes: the input file and the canonical report. Identical input yields the identical report and identical hashes — on any machine, any time. This is not an assurance statement; it is a property you can test: the Evidence publishes ten inputs, reports, and hash pairs.

Freeze & Versioning Policy

v1.01 behavior is locked. No silent changes: any change that could alter a verdict on any input ships only as a new engine version. Reports name the engine version that produced them, so a verdict can always be traced to the exact contract it was issued under.