feat(filters+nav): author navigation end-to-end — arrays on every media response, deep-linkable bookshelf filters, clickable authors

Completes the A2c acceptance scenario: click an author on a book
detail page -> land on the bookshelf filtered to everything that
author wrote (including their share of co-authored books).

- Media detail + unscoped list resolved maps expose subtitle,
  explicit, authors, publishers (the library-scoped raw branch and
  the search endpoint already did — raw rows follow the SELECT).
- SearchMediaItemsUnified SELECT carries the new columns; the search
  endpoint serializes the row directly, so clients get them there too.
- book_detail.templ renders each author as a link to
  /bookshelf?author_filter=<name>.
- Bookshelf honors filter params in the URL on load (author_filter,
  series_filter, genre_filter, publisher_filter, tags_filter,
  narrator_filter, language_filter): pre-fills the form, applies it to
  the first grid load. Comma-joined values are multi-select via the
  server-side string_to_array split. Filtered views are shareable.

Pins widened: search rows (+7 keys), resolved keys (+4); changelog
entries in docs/contract_pins.md. Android follow-up plan written to
~/.opencode/plan/bookhoard-app-v2-compat.md.

cmd/server/tests/contract_pins_test.go

@@ -662,6 +662,11 @@ func TestContractPin_SearchJSON(t *testing.T) {
 		// EXPLAIN plan-identical) and the search endpoint serializes the
 		// row directly, so they emit here.
 		"abridged", "audio_metadata",
+		// A2b/A2c (2026-10-19): + subtitle, explicit, authors,
+		// authors_search, publishers, publishers_search, narrators_search
+		// (docs/contract_pins.md changelog).
+		"subtitle", "explicit", "authors", "authors_search",
+		"publishers", "publishers_search", "narrators_search",
 	}
 
 	url := fmt.Sprintf("%s/api/media-items/search?q=%s&library_id=%s", setup.Server.URL, url.QueryEscape(fx.itemTitle), fx.libraryID)
@@ -739,10 +744,10 @@ func TestContractPin_MediaListBothBranches(t *testing.T) {
 		"library_type_name_2",
 	}
 	resolvedKeys := []string{
-		"id", "library_id", "title", "author", "isbn", "description",
+		"id", "library_id", "title", "subtitle", "author", "authors", "isbn", "description",
 		"file_path", "file_size", "mime_type", "cover_image_path",
 		"series", "series_number", "tags", "asin", "date_published",
-		"publisher", "contributors", "language", "edition", "page_count",
+		"publisher", "publishers", "explicit", "contributors", "language", "edition", "page_count",
 		"genre", "created_at", "updated_at", "format_group",
 		"manga_type", "reading_direction",
 		"series_count", "volume", "imprint", "age_rating", "web_url",

docs/contract_pins.md

@@ -152,3 +152,12 @@ cover_image_path, has_conflict, format_group, badge`.
 - User collections are dashboard-eligible by default (the
   show_on_dashboard gate is gone from GetUserCollectionsForDashboard);
   hiding stays dashboard-prefs (`hidden_collections`) territory.
+- `GET /api/media-items` (unscoped resolved-map branch) and
+  `GET /api/media-items/:id` gained the same ADDITIVE keys as the raw
+  branch: `subtitle`, `explicit`, `authors`, `publishers`.
+- `GET /api/media-items/search` rows gained the same ADDITIVE keys plus
+  the search pairs `authors_search`, `publishers_search`,
+  `narrators_search` (the unified SELECT now carries the new columns).
+- `author_filter` / `publisher_filter` are now per-element against the
+  arrays; a comma-joined value is OR-within-facet multi-select. The
+  param NAMES and single-value behavior are unchanged.

internal/database/queries.sql.go

@@ -13201,7 +13201,14 @@ SELECT
   mi.tags_search,
   mi.contributors_search,
   mi.narrators,
+  mi.narrators_search,
   mi.abridged,
+  mi.subtitle,
+  mi.explicit,
+  mi.authors,
+  mi.authors_search,
+  mi.publishers,
+  mi.publishers_search,
   mi.audio_metadata,
   mi.file_sha256,
   mi.opf_identifier,
@@ -13429,7 +13436,14 @@ type SearchMediaItemsUnifiedRow struct {
 	TagsSearch         []string           `db:"tags_search" json:"tags_search"`
 	ContributorsSearch []string           `db:"contributors_search" json:"contributors_search"`
 	Narrators          []string           `db:"narrators" json:"narrators"`
+	NarratorsSearch    []string           `db:"narrators_search" json:"narrators_search"`
 	Abridged           bool               `db:"abridged" json:"abridged"`
+	Subtitle           pgtype.Text        `db:"subtitle" json:"subtitle"`
+	Explicit           bool               `db:"explicit" json:"explicit"`
+	Authors            []string           `db:"authors" json:"authors"`
+	AuthorsSearch      []string           `db:"authors_search" json:"authors_search"`
+	Publishers         []string           `db:"publishers" json:"publishers"`
+	PublishersSearch   []string           `db:"publishers_search" json:"publishers_search"`
 	AudioMetadata      []byte             `db:"audio_metadata" json:"audio_metadata"`
 	FileSha256         pgtype.Text        `db:"file_sha256" json:"file_sha256"`
 	OpfIdentifier      pgtype.Text        `db:"opf_identifier" json:"opf_identifier"`
@@ -13508,7 +13522,14 @@ func (q *Queries) SearchMediaItemsUnified(ctx context.Context, arg SearchMediaIt
 			&i.TagsSearch,
 			&i.ContributorsSearch,
 			&i.Narrators,
+			&i.NarratorsSearch,
 			&i.Abridged,
+			&i.Subtitle,
+			&i.Explicit,
+			&i.Authors,
+			&i.AuthorsSearch,
+			&i.Publishers,
+			&i.PublishersSearch,
 			&i.AudioMetadata,
 			&i.FileSha256,
 			&i.OpfIdentifier,

internal/database/queries/queries.sql

@@ -662,7 +662,14 @@ SELECT
   mi.tags_search,
   mi.contributors_search,
   mi.narrators,
+  mi.narrators_search,
   mi.abridged,
+  mi.subtitle,
+  mi.explicit,
+  mi.authors,
+  mi.authors_search,
+  mi.publishers,
+  mi.publishers_search,
   mi.audio_metadata,
   mi.file_sha256,
   mi.opf_identifier,

internal/handlers/media.go

@@ -844,7 +844,9 @@ func (mh *MediaHandler) ListMediaItems(c *echo.Context) error {
 			"id":               uuid.UUID(item.ID.Bytes).String(),
 			"library_id":       uuid.UUID(item.LibraryID.Bytes).String(),
 			"title":            item.Title,
+			"subtitle":         utils.PgTextString(item.Subtitle),
 			"author":           utils.PgTextString(item.Author),
+			"authors":          item.Authors,
 			"isbn":             utils.PgTextString(item.Isbn),
 			"description":      utils.PgTextString(item.Description),
 			"file_path":        utils.ResolveMediaURL(item.LibraryID, pgtype.Text{String: item.FilePath, Valid: item.FilePath != ""}),
@@ -857,6 +859,8 @@ func (mh *MediaHandler) ListMediaItems(c *echo.Context) error {
 			"asin":             utils.PgTextString(item.Asin),
 			"date_published":   item.DatePublished.Time.Format("2006-01-02"),
 			"publisher":        utils.PgTextString(item.Publisher),
+			"publishers":       item.Publishers,
+			"explicit":         item.Explicit,
 			"contributors":     item.Contributors,
 			"language":         utils.PgTextString(item.Language),
 			"edition":          utils.PgTextString(item.Edition),
@@ -916,7 +920,9 @@ func (mh *MediaHandler) GetMediaItem(c *echo.Context) error {
 		"id":               uuid.UUID(item.ID.Bytes).String(),
 		"library_id":       uuid.UUID(item.LibraryID.Bytes).String(),
 		"title":            item.Title,
+		"subtitle":         utils.PgTextString(item.Subtitle),
 		"author":           utils.PgTextString(item.Author),
+		"authors":          item.Authors,
 		"isbn":             utils.PgTextString(item.Isbn),
 		"description":      utils.PgTextString(item.Description),
 		"file_path":        utils.ResolveMediaURL(item.LibraryID, pgtype.Text{String: item.FilePath, Valid: item.FilePath != ""}),
@@ -929,6 +935,8 @@ func (mh *MediaHandler) GetMediaItem(c *echo.Context) error {
 		"asin":             utils.PgTextString(item.Asin),
 		"date_published":   item.DatePublished.Time.Format("2006-01-02"),
 		"publisher":        utils.PgTextString(item.Publisher),
+		"publishers":       item.Publishers,
+		"explicit":         item.Explicit,
 		"contributors":     item.Contributors,
 		"language":         utils.PgTextString(item.Language),
 		"edition":          utils.PgTextString(item.Edition),

templates/book_detail.templ

@@ -68,7 +68,13 @@ templ BookDetail(user User, book handlers.MediaDetail, errorMessage string, tomb
 							}
 							if len(book.Authors) > 0 {
 								<h2 class="text-lg md:text-xl mb-5" style="color: var(--text-secondary)">
-									by { strings.Join(book.Authors, ", ") }
+									by
+									for i, authorName := range book.Authors {
+										if i > 0 {
+											<span>, </span>
+										}
+										<a href={ "/bookshelf?author_filter=" + url.QueryEscape(authorName) } class="hover:underline" style="color: var(--text-secondary);">{ authorName }</a>
+									}
 								</h2>
 							} else if book.Author.Valid && book.Author.String != "" {
 								<h2 class="text-lg md:text-xl mb-5" style="color: var(--text-secondary)">

web/src/bookshelf.ts

@@ -456,28 +456,66 @@ Alpine.data("bookshelf", () => ({
 }));
 
 // Standalone function - initialize the bookshelf (NOT async, like dashboard.ts)
+// A2c §5.3: deep-linkable filters. Reads known filter params from the URL
+// into the form inputs; returns true when at least one was applied. A
+// comma-joined value is a multi-select (the server splits it per element).
+function applyURLFilters(filterForm: HTMLFormElement | null): boolean {
+  if (!filterForm) return false;
+  const params = new URLSearchParams(window.location.search);
+  const filterNames = [
+    "author_filter",
+    "series_filter",
+    "genre_filter",
+    "publisher_filter",
+    "tags_filter",
+    "narrator_filter",
+    "language_filter",
+  ];
+  let applied = false;
+  for (const name of filterNames) {
+    const value = params.get(name);
+    if (!value) continue;
+    const input = filterForm.querySelector(
+      `[name="${name}"]`,
+    ) as HTMLInputElement | null;
+    if (input) {
+      input.value = value;
+      applied = true;
+    }
+  }
+  return applied;
+}
+
 function initBookshelf(): void {
+  const filterForm = document.getElementById(
+    "filter-form",
+  ) as HTMLFormElement;
+
+  // A2c §5.3: deep-linkable filters — /bookshelf?author_filter=Sapkowski
+  // pre-fills the form and applies it to the first grid load. Author
+  // links on the detail page (and anything else) can share filtered
+  // views; a comma-joined value is a multi-select (server splits it).
+  const urlApplied = applyURLFilters(filterForm);
+
   // Check if books were already rendered server-side
   const booksGrid = document.getElementById("books-grid");
   const hasServerBooks =
     booksGrid && booksGrid.querySelector("[data-book-id]") !== null;
 
-  if (!hasServerBooks) {
-    // Only trigger HTMX if no SSR books rendered
+  if (!hasServerBooks || urlApplied) {
     const librarySelect = document.getElementById(
       "library-select",
     ) as HTMLSelectElement;
     librarySelect?.addEventListener("change", () => {
       localStorage.setItem("selectedLibrary", librarySelect.value);
     });
-    if (librarySelect && librarySelect.value) {
-      const filterForm = document.getElementById(
-        "filter-form",
-      ) as HTMLFormElement;
-      if (filterForm) {
-        // Trigger initial HTMX load
-        window.htmx.trigger(librarySelect, "change");
-      }
+    if (urlApplied && filterForm) {
+      // A URL filter replaces the grid with the filtered set — the form
+      // submit serializes the library select too (it lives in the form).
+      window.htmx.trigger(filterForm, "submit");
+    } else if (librarySelect && librarySelect.value && filterForm) {
+      // Normal unfiltered initial HTMX load
+      window.htmx.trigger(librarySelect, "change");
     }
   }
   // Setup listener for HTMX swap events on the filters list