feat(collections): smart (dynamic) collections — rules evaluated live at render

Type is DERIVED, not stored: a saved ruleset makes a collection SMART,
no rules = STATIC (stored collection_items links, unchanged behavior).
No schema change — collections.auto_assign_rules JSONB already carried
the config; user's decision 2026-10-14 (handoff: live-at-render, not
refresh-on-scan; create-time Static/Smart toggle; v1 NO hybrid).

- Rule gains an enabled flag (absent = enabled, legacy rules unaffected).
- Rule CRUD: POST/PUT(DELETE) /api/collections/:id/rules[/:ruleId] — the
  survivor dead effort of the rules-builder UI finally has real
  endpoints (rules were never editable after creation; nothing ever
  re-evaluated them). First rule converts a user collection to smart;
  removing the last reverts it to static. UpdateCollectionRulesJSON
  edits ONLY the rules doc so rule CRUD cannot clobber metadata.
- Live evaluation: candidates from GetVisibleLiveMediaForRules —
  visible-library set (family lens enforced at source) + archived IS
  NULL AND missing_scan_count = 0 — any enabled rule matches, title
  order. Zero refresh hooks by design: always current by construction.
- Membership mutations (add/remove/bulk-add) are 400 on smart — v1 no
  hybrid; collection_items.excluded stays the reserved future hook.
- Rules builder page (/collections/:id/rules) first time ever routable;
  templ whole-attribute interpolation ("{ expr }" inside a quoted attr
  value is literal text, as theme-{ user.Theme } silently proved).
- UI: create modal Static/⚡Smart cards (smart create redirects into the
  rules builder), ⚡ badge + real per-card counts on the grid (smart =
  live matches, static = stored-link count), smart detail renders
  matched books with no hand-pick actions + an Edit Rules button.
- API: GET /:id gains is_smart + live books; GET /: keeps the Android
  app's default exclusion, include_auto=true surfaces smart rows with
  live counts; TestRules previews against the SAME candidates the live
  render uses (visible + live, was raw first-1000).
- FIXED pre-existing regression from 7ce7321: static collection detail
  with NO library_id returned zero books — QueryType != '' caught user
  rows ('filter' default) and routed them to dashboard sections that
  never contain them; now only real system query types go there
  (handlers + SSR). App-visible symptom: /api/collections/:id without
  library_id came back books:[] for every static collection.

Tests: collections_smart_test.go (conversion, disabled rules, mutation
guards, revert-to-static, validation, system-collection prohibition,
include_auto semantics). Full offline integration suite PASS.

templates/collections.templ

@@ -1,6 +1,18 @@
 package templates
 
-import "bookhoard/internal/handlers"
+import (
+	"fmt"
+
+	"bookhoard/internal/handlers"
+)
+
+// pluralizeBooks renders "book"/"books" for count displays.
+func pluralizeBooks(n int) string {
+	if n == 1 {
+		return "book"
+	}
+	return "books"
+}
 
 templ Collection(user User, collections []CollectionData, errorMessage string) {
 	<!DOCTYPE html>
@@ -75,7 +87,10 @@ templ Collection(user User, collections []CollectionData, errorMessage string) {
 							>
 								<div class="flex justify-between items-start mb-4">
 									<div class="text-3xl">{ col.Icon }</div>
-									<div class="flex gap-1">
+									<div class="flex gap-1 items-center">
+										if col.IsSmart {
+											<span class="badge" style="background-color: var(--accent-muted); color: var(--accent);">⚡ Smart</span>
+										}
 										<button
 											hx-get={ "/collections/" + col.ID + "/edit-modal" }
 											hx-target="#modal-container"
@@ -98,6 +113,12 @@ templ Collection(user User, collections []CollectionData, errorMessage string) {
 								</div>
 								<h3 class="text-lg font-semibold mb-2" style="color: var(--text-primary)">{ col.Name }</h3>
 								<p class="text-sm" style="color: var(--text-secondary)">{ col.Description }</p>
+								<p class="text-xs mt-3 flex items-center gap-1" style="color: var(--text-secondary);">
+									<span class="font-medium">{ fmt.Sprintf("%d %s", col.BookCount, pluralizeBooks(col.BookCount)) }</span>
+									if col.IsSmart {
+										<span>· rules-matched live</span>
+									}
+								</p>
 							</div>
 						</div>
 					}
@@ -131,8 +152,16 @@ templ CollectionDetail(user User, collection CollectionData, books []handlers.Bo
 					<div class="flex items-center gap-4">
 						<div class="grid place-items-center h-14 w-14 rounded-2xl text-3xl" style="background-color: var(--accent-muted); color: { collection.Color }">{ collection.Icon }</div>
 						<div>
-							<h1 class="text-2xl font-bold tracking-tight" style="color: var(--text-primary)">{ collection.Name }</h1>
+							<h1 class="text-2xl font-bold tracking-tight flex items-center gap-2" style="color: var(--text-primary)">
+								{ collection.Name }
+								if collection.IsSmart {
+									<span class="badge text-xs" style="background-color: var(--accent-muted); color: var(--accent);">⚡ Smart</span>
+								}
+							</h1>
 							<p class="text-sm" style="color: var(--text-secondary)">{ collection.Description }</p>
+							if collection.IsSmart {
+								<p class="text-xs mt-1" style="color: var(--text-secondary)">Membership is rules-matched live — always current, nothing to refresh.</p>
+							}
 						</div>
 					</div>
 				</div>
@@ -152,22 +181,31 @@ templ CollectionDetail(user User, collection CollectionData, books []handlers.Bo
 							/>
 						</div>
 						if !collection.IsSystem {
-							<button
-								@click="requestBulkRemove()"
-								:disabled="selectedBooks.length === 0"
-								:class="selectedBooks.length === 0 ? 'opacity-50 cursor-not-allowed' : ''"
-								class="btn btn-danger"
+							<a
+								href={ "/collections/" + collection.ID + "/rules" }
+								class="btn btn-secondary"
 							>
-								@Icon("trash", "h-4 w-4")
-								<span>Remove Selected</span>
-							</button>
-							<button
-								@click="$store.bookPicker.open()"
-								class="btn btn-primary"
-							>
-								@Icon("plus", "h-4 w-4")
-								<span>Add Books</span>
-							</button>
+								@Icon("filter", "h-4 w-4")
+								<span>Edit Rules</span>
+							</a>
+							if !collection.IsSmart {
+								<button
+									@click="requestBulkRemove()"
+									:disabled="selectedBooks.length === 0"
+									:class="selectedBooks.length === 0 ? 'opacity-50 cursor-not-allowed' : ''"
+									class="btn btn-danger"
+								>
+									@Icon("trash", "h-4 w-4")
+									<span>Remove Selected</span>
+								</button>
+								<button
+									@click="$store.bookPicker.open()"
+									class="btn btn-primary"
+								>
+									@Icon("plus", "h-4 w-4")
+									<span>Add Books</span>
+								</button>
+							}
 						}
 					</div>
 				</div>
@@ -178,7 +216,7 @@ templ CollectionDetail(user User, collection CollectionData, books []handlers.Bo
 					for _, book := range books {
 						<div class="card p-4 rounded-2xl collection-book-card" data-title={ book.Title } data-author={ book.Author } data-media-id={ book.MediaItemID }>
 							<div class="flex gap-4">
-								if !collection.IsSystem {
+								if !collection.IsSystem && !collection.IsSmart {
 									<div class="flex-shrink-0 pt-1">
 										<label class="flex items-center cursor-pointer p-2 -m-2">
 											<input
@@ -221,7 +259,7 @@ templ CollectionDetail(user User, collection CollectionData, books []handlers.Bo
 									</a>
 								</div>
 							</div>
-							if !collection.IsSystem {
+							if !collection.IsSystem && !collection.IsSmart {
 								<div class="mt-3 pt-3 border-t" style="border-color: var(--border);">
 									<button
 										@click="requestRemoveBook('{ book.MediaItemID }')"
@@ -236,7 +274,7 @@ templ CollectionDetail(user User, collection CollectionData, books []handlers.Bo
 					}
 				</div>
 			</div>
-			if !collection.IsSystem {
+			if !collection.IsSystem && !collection.IsSmart {
 				<div
 					x-data="bookPicker"
 					x-show="$store.bookPicker.isOpen"
@@ -385,6 +423,7 @@ templ CollectionDetail(user User, collection CollectionData, books []handlers.Bo
 			data-id={ collection.ID }
 			data-library-id={ libraryID }
 			data-is-system={ collection.IsSystem }
+			data-is-smart={ collection.IsSmart }
 			style="display: none;"
 		></div>
 	</html>