feat(t-paliad-133): Phase C — B1 decision tree cascade + search extension
Wires the v3 Pathway B / B1 decision-tree cascade end-to-end. The
existing Phase D search backend gains two new query params, and the
frontend gets a data-driven button-cascade UI that walks
paliad.event_categories step-by-step.
Backend extension:
- internal/services/deadline_search_service.go
- SearchOptions gains EventCategorySlug + Forums fields.
- DeadlineSearchService gains an EventCategoryService dependency
via SetEventCategoryService(); wired in main.go after both
services exist (cross-link order).
- ForumToProceedingCodes map (10 buckets per m's spec lock §10 Q8)
translates v3 forum slugs to proceeding_type codes. Lives in Go
so rebucketing = code change, not migration.
- browseRanks() new query path: when q is empty AND
EventCategorySlug is set, synthesise rank rows from the slug's
reachable concept_ids — no trigram, just sort by
concept_sort_order. Drives B1 narrowing.
- rankConcepts() + loadPills() gain optional concept_id allow-list
+ forum_codes filters via UNIQUE NULLS NOT DISTINCT-shaped IS-NULL-OR
PARAM clauses. Trigger pills (kind='trigger') always pass forum
filter — they're cross-cutting by design.
- internal/handlers/fristenrechner_search.go
- Reads new ?event_category_slug= and ?forum= (comma-separated)
query params. Forwards to SearchOptions.
- parseCSV() helper.
Frontend B1 cascade:
- frontend/src/client/fristenrechner.ts
- loadEventCategoryTree(): one-shot fetch + in-memory cache of
/api/tools/fristenrechner/event-categories.
- renderB1Cascade(slug): renders breadcrumb + step question +
button row + skip-step + step-back. Buttons walk down, breadcrumb
walks back. Empty path = root question + 6 root buttons.
- runB1Search(slug): hits /api/tools/fristenrechner/search?event_category_slug=
and reuses Phase D's renderSearchResults() for the card list.
Empty-result path shows "Schritt zurück" link (m's spec lock §10 Q6
rephrase from "Pfad lockern").
- URL state ?b1=<dot-path> round-trips. popstate restores cascade.
- Pathway B default mode flips from filter → tree (B1 is now the
discovery surface; B2 is for power users).
Frontend i18n: +1 key (deadlines.pathway.b.tree.start_question).
Frontend CSS: .fristen-b1-breadcrumb, .fristen-b1-crumb,
.fristen-b1-question, .fristen-b1-buttons, .fristen-b1-button (with
--leaf modifier border-left accent), .fristen-b1-skip,
.fristen-b1-step-back rules.
Frontend build clean (1473 keys). go build + vet + tests clean.
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