SHA-256 to BLAKE3 Coordination

[flyingrobots]

Migrated from Method backlog

This issue was created from a legacy filesystem backlog card. GitHub Issues are now the live work tracker; repository docs remain Method evidence.

Source backlog: docs/method/backlog/up-next/KERNEL_sha256-blake3.md
Original lane: up-next
Original legend: KERNEL

Original backlog card

SHA-256 to BLAKE3 Coordination

Milestone: First Light | Priority: P1 | Repo: Shared

Cross-repo planning task. Wesley currently uses SHA-256 for schema hashing. Echo uses BLAKE3. This task produces the migration specification, not the implementation.

T-2-5-1: SHA-256 to BLAKE3 migration spec

User Story: As a cross-project architect, I want a written migration plan for switching Wesley from SHA-256 to BLAKE3 so that both repos use the same hash algorithm and the transition is safe.

Requirements:

• R1: Document the current SHA-256 usage points in Wesley (schema hash, IR signature, generated code).
• R2: Document the current BLAKE3 usage points in Echo (state_root, commit_id, CAS, ident).
• R3: Define a dual-hash transition period: Wesley emits both schema_sha256 and schema_blake3 fields; Echo consumers prefer BLAKE3 when available.
• R4: Define the cutover criteria (when SHA-256 fields can be removed).
• R5: Identify breaking changes and version bumps required in both repos.
• R6: Produce the spec as a markdown document in docs/spec-hash-migration.md in the Echo repo.

Acceptance Criteria:

• AC1: Spec document exists at docs/spec-hash-migration.md.
• AC2: Spec lists every SHA-256 call site in Wesley (verified by grep).
• AC3: Spec lists every BLAKE3 call site in Echo (verified by grep).
• AC4: Dual-hash transition protocol is defined with concrete field names and version tags.
• AC5: Spec reviewed by maintainers of both repos.

Definition of Done:

• Code reviewed and merged
• Tests pass (CI green)
• Documentation updated (if applicable)

Scope: Repo: Echo (spec document). Cross-repo audit of both Wesley and Echo hash usage.
Out of Scope: Actual implementation of BLAKE3 in Wesley. Actual removal of SHA-256. Performance benchmarking of BLAKE3 vs SHA-256 in Node.js.

Test Plan:

• Goldens: N/A (specification document).
• Failures: N/A.
• Edges: N/A.
• Fuzz/Stress: N/A.

Blocked By: none
Blocking: none

Est. Hours: 4h
Expected Complexity: ~0 LoC (prose specification only)

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[coderabbitai]

🔗 Related PRs

#93 - PR-02: docs: BLAKE3 audit checklist [merged]
#309 - feat: add Doghouse PR flight recorder [merged]
#326 - Echo contract hosting roadmap [merged]
#329 - Stack Witness 0001 fixture-backed jedit walking skeleton [merged]
#344 - feat(wesley): consume canonical requirements artifacts [merged]

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