docs: clarify proposal source and digest bindings

protocols/EVIDENCE.md

@@ -2,6 +2,8 @@
 
 Read exact source revisions and immutable extraction maps supplied by the service. Bind each factual assertion or field to source/extraction IDs, location, quote and assertion digest under the published schema. For node claims, use the exact `claims[n].text`, `assumptions[n].text` or `limitations[n].text` assertion path that owns the statement; claim IDs must be unique across all three groups. A local extraction may help prepare a draft; it cannot impersonate the service's archived revision or locator map.
 
+Capture does not register a source. For new captures, use the exact returned source candidate in a `register_source` proposal operation, or cite a source revision already accepted and readable in GEWU. Cite the capture's exact source revision and extraction IDs. Finish the assertion text and evidence set before computing bindings: evidence `assertion_digest` and assessment `assertion_digest` bind to the normalized exact claim text, while assessment `evidence_digests` bind to the complete final evidence objects. If text or evidence changes, recompute all dependent digests and the containing proposal payload digest as described in [the contribution protocol](CONTRIBUTIONS.md#register-sources-and-bind-evidence).
+
 Record material assumptions and limitations as their own evidence-backed claim groups. Do not bury them in a summary or infer them from conditions on an edge. Each statement needs its own support assessment bound to its exact assertion and evidence, and it appears separately in the read interface. If the source does not establish a proposed assumption or limitation, keep it explicitly unsupported or omit it.
 
 Quote occurrence, semantic support, source reliability, model confidence and freshness are different assessments. A matching quote does not establish that the number, unit, population or qualifiers support the assertion. Record support rationale and the actual assessor. Routine same-agent assessment is allowed when policy permits; do not describe it as independent human review.