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Adds capability.wiki.{shard-orchestration, adapter-contract, page-model,
coordination-journal, overlay, federation-models, engine-typed-extensions}
with honest D/A/C/R maturity vectors, relations, and shard-wiki spec/test
evidence; updates registry/indexes/capabilities.yaml. reuse-surface validate: ok.
Source: shard-wiki SHARD-WP-0013 T1.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
103 lines
3.4 KiB
Markdown
103 lines
3.4 KiB
Markdown
---
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id: capability.wiki.overlay
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name: Overlay-Before-Mutation Write Path
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summary: Non-destructive edits (draft -> patch -> apply-under-drift) that let read-only, rate-limited, or lossy backends be edited safely without silent remote mutation.
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owner: shard-wiki
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status: draft
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domain: helix_forge
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tags: [wiki, overlay, patch, write-path, conflict, shard-wiki]
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maturity:
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discovery:
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current: D5
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target: D6
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confidence: high
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rationale: >
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Overlay lifecycle and apply-under-drift semantics are specified (ADR-05, blueprint
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Section 8.6) and implemented as a single principled write path.
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availability:
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current: A2
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target: A4
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confidence: medium
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rationale: >
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OverlayEngine (draft/patch/apply), writable adapter, and InformationSpace.edit
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exist as a source module; three-way merge is not (refuse-on-drift only).
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external_evidence:
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completeness:
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level: C2
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name: Partial
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confidence: medium
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basis: scope_vs_intent_and_consumer_expectations
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satisfied_expectations:
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- draft -> patch -> apply with fast-forward / refuse-on-drift / keep-draft outcomes
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- no silent remote mutation; overlay_state surfaced in provenance
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broken_expectations:
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- three-way / auto merge not implemented (refuse-on-conflict only)
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out_of_scope_expectations:
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- federation propagation of applied overlays
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reliability:
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level: R1
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confidence: low
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basis: consumer_quality_signals
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known_reliability_risks:
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- early implementation; conflict handling is detect-and-refuse only
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discovery:
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intent: >
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Make any sub-write-through backend editable safely: an edit is an overlay first, applied
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only on explicit intent and only when the source has not drifted.
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includes:
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- overlay drafts recorded as coordination-canonical events
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- patch rendering (unified diff)
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- apply-under-drift (fast-forward / refuse / keep-draft)
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excludes:
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- destructive write without drift check
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use_cases:
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- "shard-wiki UseCaseCatalog UC-04, UC-26, UC-29 (remix primitives, overlay)"
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availability:
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current_level: A2
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target_level: A4
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current_artifacts:
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- "shard-wiki/src/shard_wiki/coordination/overlay.py"
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- "shard-wiki/src/shard_wiki/coordination/patch.py"
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consumption_modes:
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- source module
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relations:
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depends_on:
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- capability.wiki.coordination-journal
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- capability.wiki.adapter-contract
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evidence:
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documentation:
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- "shard-wiki/spec/FederationRequirements.md (ADR-05)"
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- "shard-wiki/spec/CoreArchitectureBlueprint.md (Section 8.2, 8.6)"
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tests:
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- "shard-wiki/tests/test_apply.py"
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- "shard-wiki/tests/test_write_path_integration.py"
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consumer_guidance:
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recommended_for:
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- safe editing over read-only / rate-limited / lossy backends
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not_recommended_for:
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- workflows needing automatic conflict resolution today
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known_limitations:
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- merge is detect-and-refuse; three-way merge is future work
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---
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# Overlay-Before-Mutation Write Path
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One principled write path: every edit drafts an overlay (a coordination-canonical event),
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renders as a patch, and applies under drift checks — fast-forwarding a writable target,
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keeping a local draft on a read-only target, and refusing (never clobbering) on external drift.
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## Assessment notes
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### Discovery
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Specified in FederationRequirements ADR-05 and CoreArchitectureBlueprint Section 8.2/8.6.
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### Availability
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`overlay.py` + `patch.py` + `InformationSpace.edit` ship the path; built in SHARD-WP-0008.
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