Gravity Migration

02 · Evidence

Every rule can say where it came from.

The Standard's specs are read by people, so they don't mention paragraphs or job steps. A separate evidence ledger holds that link, and AI can do most of the reading, as long as a person confirms what it found.

The chain from artifact to proof. The ACLP210 program leads to evidence entry EV-014, confirmed by a person. That supports rule LPF-003, which is tested by a rule test, and proven by a parallel run in which difference DIFF-007 is closed. ARTIFACTACLP2102200-ASSESS-FEECOBOL, 1987 EVIDENCEEV-014"fee truncates"confirmed: M. Bell RULELPF-0035%, fractionsdropped, $10 min TESTTestLPF003$1,234.70gives $61.73 PROOFParallel runDIFF-007 closedmatches production The rule names none of what's on its left. The ledger connects them, and it's deleted along with the source.

The ledger

A claim is what it does, not what it should do.

Keep the ledger's language flat. "The fee calculation drops fractions of a cent" is evidence. "The fee should be truncated" is a decision, and it belongs to the process owner.

That line is what makes AI extraction safe. A model can read a million lines and propose claims all day, because a proposed claim commits nobody to anything.

Specs stay clean, too. The ledger lives in migration/evidence/, beside domains/ and apps/, and it can be removed when the source is gone.

migration/evidence/late-payment-follow-up.md
## EV-014 — The late fee drops fractions of a cent
- Claim: The fee is 5% of the amount due, and anything
  past two decimals is discarded rather than rounded.
- Source: ACLP210 2200-ASSESS-FEE (no ROUNDED on COMPUTE)
- Kind: code
- Extracted by: AI — 2026-11-05
- Status: confirmed
- Confirmed by: Marcus Bell — 2026-11-05
- Disagrees with: The fee schedule says "5%", no rounding stated
- Supports: LPF-003

Where to look

The main program is only one witness.

Tidewater's late fee and its follow-up rules were scattered across six kinds of source. Reading only the COBOL would have missed most of them.

Source kindFound at TidewaterWould be missed by
Program5% fee and $10 minimum, in ACLP210Nothing; everyone looks here
Sort cardGuaranteed loans skip follow-up, in INCLUDE CONDReading only the COBOL
Code tableEach bank's grace days, in TWCODESReading only source libraries
Server config10-day quote validity, in quote.propertiesReading only the repository
Stored procedureA loan needs a zero balance to close, in SP_CLOSE_LOANReading only the table definitions
Data profileAn undocumented status H on 41 loansReading only code and comments

Rules

MIG-005 to MIG-008

  1. MIG-005

    Every proposed rule cites at least one evidence entry.

  2. MIG-006

    A claim extracted by an AI stays proposed until a named person confirms it.

  3. MIG-007

    Evidence records what the system does; only a person decides whether it should keep doing it.

  4. MIG-008

    Where sources disagree, production behavior is the evidence of what happens, and the disagreement becomes an open question.

evidence-entry.md
## EV-nnn — <short claim>

- **Claim:** <what the system does, in plain words; no judgment about whether it should>
- **Source:** <artifact and lines, for example ACLP210 2200-ASSESS-FEE, or a job log and date>
- **Kind:** code | config | sort card | stored procedure | data profile | observed behavior | interview
- **Extracted by:** <person or AI model> — YYYY-MM-DD
- **Status:** proposed | confirmed | disputed (MIG-006)
- **Confirmed by:** <named person> — YYYY-MM-DD
- **Disagrees with:** <other evidence, or none>; if so, open a question (MIG-008)
- **Supports:** <rule ID, or "out of scope" with the reason (MIG-039)>