CEID Phase 2: Assay Toolkit adapter — pack manifest + receipt header

[Haserjian]

Summary

CEID adoption for Assay Toolkit. Pack manifests and receipt artifacts get universal headers. Decision CEIDs are referenced, not invented here.

Parent spec: ccio/docs/SPEC-0001-canonical-decision-envelope-and-ceid.md
Golden corpus: ccio/tests/fixtures/ceid_golden_corpus.py → ASSAY_TOOLKIT_TYPE_MAP

First Lane

Artifact	Type Code	Is CDE	Rationale
ProofPack manifest	pak	No	Transport/packaging — evidence, not decision
ADCCredential	dec	Yes	Decision credential is inherently a decision
ToolCallReceipt	tol	Yes	Tool action representing an evaluated choice

Key Design: decision_ceids vs artifact_refs

Proof packs reference multiple decision artifacts. Distinguish clearly:

• decision_ceids: decisions materially evidenced by the pack
• source_ceids or artifact_refs: broader upstream references

decision_ceids must not become a junk drawer.

Target Files

Production

File	Change
src/assay/ceid.py (new, vendored)	Vendored copy of ccio's ceid.py
conformance/generate_corpus.py	Add CEID + universal header to generated pack manifests
Pack manifest schema	Add ceid, artifact_type, source_system, ts_recorded, decision_ceids

Tests

File	What It Validates
tests/test_ceid_manifest.py (new)	CEID presence on pack, decision_ceids references valid
tests/test_vendored_ceid.py (new)	Vendored ceid.py matches CCIO golden corpus

Acceptance Criteria

• One generated proof pack contains CEID-bearing manifest
• Manifest references at least one CEID-bearing decision artifact
• decision_ceids contains only valid CEIDs with CDE-class type codes
• Verification flows unchanged — CEID is additive metadata
• MCP proxy receipt format aligned with CEID + header rules
• Vendored GOLDEN_CORPUS_VERSION matches CCIO source

Guardrails

• Manifest schema stability: One canonical fixture with CEID header + backward-compatible verification
• decision_ceids naming rigor: Only decisions materially evidenced, not all upstream references
• Verification truth: pack_root_sha256 remains verification truth; CEID is addressing metadata

Dependencies

• CCIO and Loom CEID adapters should be green first (stable decision CEIDs to reference)

[Haserjian]

Migration Sequence

This is Step 6 in the CEID migration sequence (ccio/docs/CEID-MIGRATION-SEQUENCE.md).

Blocked by: Steps 1–5 (CCIO + Loom green, corpus pinned, resolver proven, mixed-chain verified)
Parallel with: Haserjian/agentmesh#32, Haserjian/assay-ledger#7

Do not start before:

• Haserjian/ccio#90 done (CCIO adapter)
• Haserjian/Loom#94 done (Loom adapter)
• Haserjian/ccio#91 done (mixed-chain resolver)
• Step 3 corpus pin verified
• Step 5 mixed-chain end-to-end passed