Register shard-wiki capabilities (7 wiki.* registry entries)

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>

registry/capabilities/capability.wiki.coordination-journal.md

@@ -0,0 +1,103 @@
+---
+id: capability.wiki.coordination-journal
+name: Event-Sourced Coordination Journal
+summary: An append-only, totally-ordered-per-space decision log (overlays, bindings, aliases, merges, forks) whose current state is a derived fold; git-addressable history.
+owner: shard-wiki
+status: draft
+domain: helix_forge
+tags: [wiki, event-sourcing, coordination, git, journal, shard-wiki]
+
+maturity:
+  discovery:
+    current: D5
+    target: D6
+    confidence: high
+    rationale: >
+      Keystone resolved across two architecture reviews: coordination-canonical state
+      as an append-only decision log with a per-space append authority; current state
+      is a derived fold (derived = f(log)).
+  availability:
+    current: A2
+    target: A4
+    confidence: medium
+    rationale: >
+      In-memory DecisionLog + fold work as a source module; the git-backed store with a
+      per-space lease (the production backing) is planned.
+
+external_evidence:
+  completeness:
+    level: C2
+    name: Partial
+    confidence: medium
+    basis: scope_vs_intent_and_consumer_expectations
+    satisfied_expectations:
+      - append-only, totally-ordered-per-space log with read-your-writes
+      - derived fold to aliases + transitively-merged equivalence groups
+    broken_expectations:
+      - git-backed storage and per-space lease/append-authority not yet implemented
+    out_of_scope_expectations:
+      - general-purpose event bus
+  reliability:
+    level: R1
+    confidence: low
+    basis: consumer_quality_signals
+    known_reliability_risks:
+      - in-memory backing only; cross-process durability pending
+
+discovery:
+  intent: >
+    Make coordination-canonical decisions durable and git-addressable as events, with the
+    queryable current state always recomputable by replay.
+  includes:
+    - append-only decision log, totally ordered per information space
+    - derived fold to current coordination state (aliases, equivalence groups, overlays)
+    - per-space append authority (concurrency model)
+  excludes:
+    - storing derived/disposable union state
+  use_cases:
+    - "shard-wiki UseCaseCatalog UC-29, UC-33 (history, attribution, coordination journal)"
+
+availability:
+  current_level: A2
+  target_level: A4
+  current_artifacts:
+    - "shard-wiki/src/shard_wiki/coordination/decision_log.py"
+  target_artifacts:
+    - git-backed log store with per-space lease
+  consumption_modes:
+    - source module
+
+relations:
+  supports:
+    - capability.wiki.shard-orchestration
+    - capability.wiki.overlay
+
+evidence:
+  documentation:
+    - "shard-wiki/spec/CoreArchitectureBlueprint.md (Section 8.1)"
+  tests:
+    - "shard-wiki/tests/test_decision_log.py"
+
+consumer_guidance:
+  recommended_for:
+    - durable, replayable, git-addressable coordination state for a federated space
+  not_recommended_for:
+    - high-frequency general event streaming
+  known_limitations:
+    - production git backing + lease are still on the roadmap (SHARD-WP-0009)
+---
+
+# Event-Sourced Coordination Journal
+
+The keystone: coordination-canonical state (overlays, equivalence bindings, aliases, merges,
+forks) is an append-only **decision log**, totally ordered per information space; the queryable
+current state is a derived **fold** of the log (`derived = f(log)`). The log is git-addressable,
+giving history/patch/review/backup for coordination decisions for free.
+
+## Assessment notes
+
+### Discovery
+Resolved across the round-1/round-2 architecture reviews (CoreArchitectureBlueprint Section 8.1).
+
+### Availability
+`decision_log.py` ships an in-memory, totally-ordered log + fold; git+lease backing is planned.