Contract Inverse Admission Hook

[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_contract-inverse-admission-hook.md
Original lane: up-next
Original legend: KERNEL

Original backlog card

Contract Inverse Admission Hook

Status: planned kernel/runtime implementation.

Depends on:

• Installed Wesley contract host dispatch
• Contract reading identity and bounded payloads
• 0018 - Contract-Hosted File History Substrate

Why now

Undo must be witnessed history. A contract knows how to invert its own domain
semantics; Echo should provide a generic admission hook, not a generic blind
WarpOp inverse API.

What it should look like

Given:

• target tick, receipt, or range;
• current target coordinate;
• contract family;
• inverse policy;
• installed contract artifact;

Echo asks the contract to produce one or more inverse intents or a typed
obstruction. Produced inverse intents are admitted normally.

Acceptance criteria

• Building hello from five insert ticks then unapplying C2 appends one inverse
  tick.
• Reading at the new frontier is helo.
• Original C2 remains in provenance.
• Provenance length increases by one.
• Inverse receipt links to the target receipt.
• Unmappable spans, missing receipts, unavailable inverse fragments, and
  contract-version mismatches return typed obstructions.
• Sequence unapply applies deterministic ordering or reports partial success
  explicitly.
• TickReceipt inverse blob or inverse fragment digest resolves through
  retention when inverse material is retained.
• GC, compaction, wormhole, or checkpoint compression either preserves required
  inverse evidence, provides a rehydratable cold archive, or obstructs
  fine-grained unapply inside compressed ranges.

Non-goals

• Do not delete or rewrite old ticks.
• Do not expose WarpOp replay patches as user-facing undo semantics.
• Do not silently succeed when inverse evidence is missing.

[coderabbitai]

🔗 Related PRs

#323 - Witnessed suffix admission evaluator [merged]
#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]

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