> ## Documentation Index
> Fetch the complete documentation index at: https://www.docs.forgeshipyard.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Sources vs. Decisions

> The two kinds of things Forge handles, and why keeping them separate is the point.

export const AuditSignature = () => <Tooltip tip="A cryptographic proof that a specific person made a specific decision at a specific time, and it has not been altered since.">audit signature</Tooltip>;

export const DecisionLedger = () => <Tooltip tip="An append-only record of every engineering decision and the reasoning behind it. Decisions are never edited, only superseded.">decision ledger</Tooltip>;

export const Source = () => <Tooltip tip="Anything that comes into the system as input: rules, drawings, datasheets, prior vessel records. Locked once ingested.">source</Tooltip>;

<Note>
  **In plain terms:** A **source** is something that comes in (a rule, a drawing, a
  prior vessel's records). A **decision** is something the system reasons out from
  those sources. Forge keeps them in separate places on purpose.
</Note>

## Sources: what comes in

A <Source /> is any input: rules, drawings, datasheets, prior vessel records. Two
things are always true of a source:

* It is **immutable once ingested.** Once a source is in the system, it is locked.
  It is never quietly edited.
* It carries its **version, authority, and provenance.** The system always knows
  which version of a rule this is, how much weight it carries, and exactly where
  it came from.

## Decisions: what gets reasoned out

A **decision** is what the system concludes *from* sources: which rule applies,
what evidence supports it, what design choice was made, what it replaced.

Decisions are first-class objects. They live in the <DecisionLedger /> with their
own structure, their own life cycle, and their own <AuditSignature />. And
critically, a decision is **replayable**: given the same sources at the same
versions, the same decision should be reconstructable from scratch.

## Three trust levels for sources

Not every source carries the same weight. Every source in the registry is tagged
with one of three trust levels:

| Trust level   | What it means                                   | Example                                                                               |
| ------------- | ----------------------------------------------- | ------------------------------------------------------------------------------------- |
| **Authority** | Binding for this jurisdiction or scope          | ABS Rules, USCG CFR sections, yard standards within their domain                      |
| **Evidence**  | Non-binding precedent                           | Prior vessel records, completed-build outcomes, inspection records                    |
| **Reference** | Informational only, never sufficient on its own | IACS or IMO documents when not applicable here, research datasets, vendor whitepapers |

This trust grade is **separate from the document type.** The same ABS Rules can be
*authority* for one project and *reference* for another (a USCG-only project, for
example). A yard's own standard can be authority inside the yard and reference for
an outside review.

## The rule that ties it together

Every claim the system makes must cite its source. A claim that an ABS rule applies
cites that ABS rule and its version. A claim about a measurement cites the
measurement record. A claim about precedent cites the prior vessel record.

> Nothing the system says is ungrounded.

That is what makes a decision defensible later: you can always trace it back to the
exact sources, at the exact versions, that produced it.