Versioned Contract And API Compatibility

[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/v0.1.0/PLATFORM_versioned-contract-api-compatibility.md
Original lane: v0.1.0
Original legend: PLATFORM

Original backlog card

Versioned Contract And API Compatibility

Status: local package-boundary slice implemented; release automation remains.

Depends on:

• Contract-aware receipts and readings
• External contract proof fixture

Why now

Developers need clear "this generated package fits this Echo runtime" behavior.
Ambiguous schema, ABI, codec, or generator drift should be rejected at install
or call time, not discovered through malformed receipts.

Required identity

v0.1.0 needs stable version identity for:

• Echo ABI version;
• Wesley generator version;
• contract package version;
• schema hash;
• artifact hash;
• codec id;
• generated helper compatibility;
• package install compatibility checks.

Acceptance criteria

• Package installation records version and compatibility metadata.
• Version, schema, artifact, codec, or helper mismatch fails closed.
• Receipts and readings can cite the installed package identity they came
  from.
• The external proof fixture documents the Echo/Wesley versions used.
• Release notes identify the supported ABI/package compatibility set.

Implemented local slice

echo-registry-api now requires Echo contract ABI, Wesley generator, and
contract-host helper API compatibility in generated registry metadata and host
verification policy. echo-wesley-gen --contract-host emits those constants,
and warp-core carries the verified identity into installed package evidence
for receipts and readings.

Non-goals

• Do not support arbitrary historical package migrations in this slice.
• Do not accept drift by falling back to best-effort decoding.
• Do not encode application-domain version policy in Echo core.

[coderabbitai]

🔗 Related PRs

#326 - Echo contract hosting roadmap [merged]
#365 - feat(wesley): emit query observer host helpers [merged]
#368 - feat(core): connect installed contract intent pipeline [merged]
#371 - feat(core): advance v0.1 contract evidence and retention [merged]
#380 - feat(core): expose retained evidence posture on readings [merged]

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