Macro-4 Draft Object Replace Contract — R2-B2 (2026-06-19)

Date: 2026-06-19 · Workstream: R2-B2-MACRO-4-STAGING-WORKBENCH-IO-CONTRACT-TD-ENTRY-GATE-2026-06-19 (Deliverable 16 of 90) · Editorial revision: rev1 Class: draft object replace contract · READ-ONLY · NON-ENACTING · NON-AUTHORIZING · CONCEPT-ONLY · NO write performed.

Metadata convention. Editorial revision (rev1) only. Storage revision/content_length authoritative at read time.

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0. Status and non-authorization

STATUS: PASS — engineering / design-only. How a draft object is replaced with no cascade. Engineering PASS ≠ authority PASS. Default: HOLD.

1. Purpose

Define the "replaced separately" property: swap a wrong draft for a better one without breaking any other LEGO part.

2. Sources / evidence read

Inspect-producer §10 (replace by swapping channel, keep the B3 contract); Macro-3 delete-fast risk map; LEGO boundary map (3). Main process, no reader-agents.

3. Accepted baseline (carried)

B2's channel is a replaceable internal (B2-AC-7); the contract (read uncertified → write inspect_*) is invariant across the swap.

4. Evidence / analysis — replace contract

Property	Requirement
Contract-invariant	the IO contract stays fixed; only the internal (channel/decomposition) changes
No cascade	replacing one draft breaks no other draft and no production surface
Disposal-first	the old draft is delete-fast'd before/independently of the new one
Pointer-only links	cross-references are pointers; a replaced draft leaves no dangling write

5. Contract / requirement / matrix / result

Replacement = (delete old disposable unit) + (born new disposable unit) against the same IO contract. Because the contract is the only coupling, a replacement is local and safe. No replacement is performed here.

6. Owner-gated future work

Replacing a built draft is Owner-gated; forbidden now.

7. What remains unresolved

Replacement mechanics are FUTURE_TECHNICAL_DESIGN_REQUIRED.

8. Ready for GPT/Codex review

Yes — Codex should confirm replacement touches only the internal, never the contract or production.