# Evidence and Provenance

> Admission, preservation, integrity, derivation, and source-status requirements.

Evidence records a source claim or observation. Admission makes that claim
durable; it does not make it current truth.

## Admission

**TM-EVD-001 — Admission is not promotion.** Admitting evidence **MUST NOT** by
itself change current truth.

**TM-EVD-002 — Source preservation.** An implementation **MUST** preserve the
source representation when the medium and data policy permit it. When the
source cannot be retained, the evidence record **MUST** state what was
observed, by whom or what, when, and why the original is unavailable.

**TM-EVD-003 — Provenance.** Every evidence record **MUST** identify its source,
capture or receipt event, integrity mechanism where applicable, and any actor
or process that transformed it before admission.

**TM-EVD-004 — Derivative distinction.** Extraction, transcription,
normalization, classification, and model-produced interpretation **MUST** be
represented as derivative results. A derivative **MUST NOT** replace or edit
the source evidence it interprets.

**TM-EVD-005 — Correction by addition.** Once evidence supports an accepted
change, its substantive content **MUST NOT** be rewritten. A correction or
later clarification **MUST** enter as new evidence linked to the earlier
record.

**TM-EVD-006 — Evidence status.** An implementation **MUST** distinguish at
least admitted evidence from evidence that is untrusted, failed processing,
withdrawn by its source, superseded by a later claim, or rejected for a stated
use when those states occur.

## Integrity

The specification does not mandate cryptographic hashing. The integrity
mechanism must be proportional to the consequence and media:

- a file may use byte identity and SHA-256;
- an API observation may preserve the request contract, response subset,
  endpoint identity, and observation time;
- a human statement may preserve an attributable note or signed record;
- a physical observation may preserve the observer, method, time, and
  measurement uncertainty.

**TM-EVD-007 — Detectable substitution.** When evidence bytes or values are
retained, the implementation **MUST** provide a deterministic way to detect
substitution or unrecorded alteration after admission.

## Data minimization

**TM-EVD-008 — Bounded retention.** Evidence retention **MUST** obey the
system's declared privacy, security, legal, and ownership boundaries. A truth
machine is not permission to copy every source into one store.

A recovery-safe reference, manifest, or curated observation may be more
truthful than an uncontrolled duplicate. The record must say what it proves
and what remains outside the system.