tag/property/closed value should be hard retracted

docs/adr/0009-hybrid-schema-deletion.md

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+# ADR 0009: Hybrid Delete Semantics for Schema Entities
+
+Date: 2026-03-18
+Status: Accepted
+
+## Context
+`delete-blocks` and page deletion now recycle entities instead of hard deleting
+them.
+
+That works well for ordinary content because users can restore deleted blocks
+and pages from Recycle, and active UI/search can treat recycled content as
+hidden state.
+
+It does not work as well for DB-schema entities.
+Tag pages, property pages, and closed-value blocks continue to exist after
+deletion and can leak into active semantics such as:
+- class/property enumeration
+- closed-value lookup and scoped choices
+- bidirectional/property-derived views
+- sync repair logic when schema roots disappear but dependents still reference
+  them
+
+At the same time, sync still needs to remain robust when `:db/retractEntity`
+appears again for this subset of entities and for their descendants.
+
+## Decision
+1. Adopt hybrid delete semantics:
+   - recycle ordinary blocks and ordinary content pages
+   - hard retract tag/class pages, property pages, and closed-value blocks
+2. When deleting a schema root page, retract the schema page tree rather than
+   moving it to Recycle.
+3. When deleting a closed-value block, retract the choice entity directly.
+4. Keep raw entity access unchanged; deleted schema entities should disappear by
+   DB state, not by UI-only filtering.
+5. Keep recycle-aware behavior for content entities:
+   - deleted-state page route for recycled content
+   - deleted styling for recycled references/embeds
+   - search/index filtering for recycled content and descendants
+6. Make sync robust for missing content locations:
+   - if a content node loses `:block/parent` or `:block/page` during sync
+     application, move it to Recycle rather than leaving it structurally
+     invalid
+7. Preserve valid `:db/retractEntity` handling in sync sanitize/rebase/apply for
+   schema deletions.
+
+## Consequences
+- Positive:
+  - Schema entities return to true disappearance semantics, which matches how
+    most schema helpers already reason about deletion.
+  - Content keeps recycle/restore UX.
+  - Sync has a deterministic repair rule for orphaned content blocks.
+- Negative:
+  - Delete semantics are now mixed by entity kind, so the rule must remain
+    centralized in the outliner/domain layer.
+  - Some old recycled schema entities may still need active-use filtering until
+    users delete them under the new semantics.
+  - Sync logic is slightly more complex because it must accept both recycle and
+    hard-retract flows.
+
+## Verification
+- Model/helper coverage:
+  - `bb dev:test -v frontend.db.db-based-model-test/get-all-classes-filters-recycled-test`
+  - `bb dev:test -v frontend.db.db-based-model-test/get-all-properties-filters-recycled-test`
+- Sync repair coverage:
+  - `bb dev:test -v frontend.worker.db-sync-test/missing-parent-after-remote-retract-moves-child-to-recycle-test`
+- Additional targeted coverage to keep or extend:
+  - page/property/closed-value delete semantics
+  - bidirectional helper behavior with deleted or recycled entities
+  - search index invalidation for recycled content