docs: clarify proposal source and digest bindings

protocols/CONTRIBUTIONS.md

@@ -2,6 +2,18 @@
 
 Before a connected workflow, call `diagnostics` and compare the discovered MCP tool names and input schemas with `contracts/service-v1.json`; its catalog digest and record-schema hashes pin the local GEWU v1 contract. Diagnostics reports the authenticated role, authorized projects/capabilities, explicit selected scope, source-transfer limits, service/catalog versions and canonical/index revisions without returning credentials or principal IDs. `connection_status=authenticated` proves only this call; `workflow_status=not_verified` means native workflow acceptance remains separate. The MCP tool inventory must match exactly. If tools are absent or schemas differ, stop before mutation and report the drift. `proposal_evaluate` is the deterministic preflight; the service's `proposal_submit` response remains authoritative. Owner decisions use a separate owner transport and are not available to agents. Runs are agent-owned, explicitly scoped service records; they do not schedule work or grant capability.
 
+## Build attributable proposals
+
+Use the stable principal ID assigned to the configured agent credential. The credential must have the `agent` role and grants for every affected project. Set `ProposalRevision.proposer_id`, each proposed node's `agent_id`, and each claim assessment's `assessor_id` to that principal ID. Do not substitute a model name, harness name or human display name. Diagnostics intentionally omits principal IDs; obtain the expected ID from the credential's operator-provided configuration, never guess it. If the identity is unknown or the service rejects attribution, stop and report the mismatch rather than changing IDs speculatively.
+
+## Register sources and bind evidence
+
+Capture tools stage and archive source material but do not register its source record. Before evaluating a proposal that cites a newly captured source, include the exact returned `source_candidate` as a `register_source` operation in the same proposal, or confirm that the source revision was already accepted and is readable. Use the candidate's exact `revision_id` as each citation's `source_revision_id`, and the capture's returned `extraction_id`; do not synthesize or copy IDs from another capture. A source operation and a node operation may be evaluated together.
+
+Finalize claim text and evidence before creating support assessments or digests. Every evidence `assertion_path` must name its exact typed claim field (`claims[n].text`, `assumptions[n].text` or `limitations[n].text`). Its `assertion_digest` must bind to that exact claim text. Set the assessment's `assertion_digest` to the same value and `evidence_digests` to the digests of the claim's final evidence objects. Any edit to claim text or evidence requires regenerating those dependent values and the proposal `payload_digest` before `proposal_evaluate`.
+
+Use the canonical GEWU digest rules, not a hash of the raw quote or raw request text. Canonical JSON is UTF-8 JSON with Unicode preserved, sorted keys, no insignificant whitespace and no NaN values. The assertion digest is SHA-256 of canonical JSON `{"assertion": normalized_text}`, where text has CRLF and CR converted to LF and is normalized to Unicode NFC. An evidence digest is SHA-256 of canonical JSON for the complete evidence object in schema JSON form. The assessment's `evidence_digests` must match those final evidence digests. The proposal payload digest is SHA-256 of canonical JSON for the final operations serialized as GEWU v1 contract records. Recompute it after adding/removing/changing any operation. If the client cannot reproduce these rules, stop before submission and report that digest generation is unavailable.
+
 `list_projects` exposes authorized IDs, and `get_project_context` returns the selected authorized project's north star, key questions, watch list, taxonomy extensions, research lenses and explicitly saved ingest guidance without exposing its autonomy policy. Projects default to technical, conceptual, cultural-historical and financial-market lenses. These are coverage prompts, not quotas. Use this context for ingest/curation; keep objective and scope explicit and never infer authority from a folder or project name.
 
 When available, `ingest_review_create` stores a source-bound review flag. Submit it after or alongside normal proposal processing, never as a reason to wait on human review before evaluating/submitting plausible findings. Bind it to the durable run and an extraction owned by the submitting agent and granted project; the exact excerpt and locator must match the staged extraction. A queue entry is a notification/filter and feedback record, not a proposal, source registration, acceptance result or publication. Human reviewers may confirm relevance, mark it irrelevant or defer feedback. Reusable project guidance is added to future context only when a human explicitly saves a rule. If the review operation is absent, preserve and report plausible uncertain material rather than silently deferring it.