feat(web): 分野詳細に「この分野を設定している項目」逆参照を追加

docs/spec/web-ui.md

@@ -35,6 +35,7 @@
 | GET /{tenant-uuid}/cftree/doc/{doc-uuid}/item/{item-uuid} | Same tree view with an item selected via the **URL path** — the canonical, shareable, reload-safe form that in-tree navigation pushes (`hx-push-url`). Opening/reloading/sharing reconstructs the tree (the ancestor path expanded to the item) + the item's full detail via SSR. |
 | GET /{tenant-uuid}/cftree/doc/{doc-uuid}/detail/{item-uuid} | HTML fragment of an item's detail (for the HTMX right pane). |
 | GET /{tenant-uuid}/cftree/doc/{doc-uuid}/document | HTML fragment of the document's own detail (right pane). Separate from `/detail/{item}` to avoid identifier collisions. |
+| GET /{tenant-uuid}/subject/{subject-uuid}/items | HTML fragment: the next page of "items setting this subject" for the CFSubject detail page ("Show more" pagination). Same `subject_items.html` markup as the inline SSR. 404 unless the id is a CFSubject in this tenant. |
 | GET /{tenant-uuid}/uri/{uuid} | Resource detail page (HTML by default; **303 See Other** to the matching CASE API endpoint when the `Accept` header signals a JSON client — see [api-spec.md](api-spec.md#tenanturiuuid-content-negotiation)). |
 
 **Manual list ordering (`display_order`)**: both lists honor an optional `display_order` integer (on `tenants` / `cf_documents`) so an operator can pin/arrange entries without renaming. Smaller = higher; `NULL` (the default) sinks below all explicitly-ordered entries and then sorts alphabetically. It's a compeito-local display field — not a CASE field, never emitted in CASE export, and preserved on re-import. Set it via `cli.py tenant update --display-order N` / `--clear-order` and `cli.py doc update --display-order N` / `--clear-order` (see [cli.md](cli.md)).
@@ -216,6 +217,8 @@ When `/uri/{uuid}` resolves to a lookup, show common + specific fields:
 | Specific fields | typeCode, hierarchyCode, licenseText, etc. (only when present) |
 | lastChangeDateTime | ISO 8601 |
 
+**CFSubject — "Items setting this subject" (reverse lookup):** a CFSubject's card adds a section listing CFItems **in the same tenant** whose `subjectURI` references this subject (the reverse of CFItem → CFSubject). It shows the total count + the first page (top 20) inline (SSR), then a **"Show more"** button that appends the next page via HTMX from `GET /{tenant}/subject/{subject-id}/items?offset=&limit=` (`Cache-Control: public, max-age=86400`; the button is self-perpetuating — each click swaps it for the next page + a fresh button, like the lazy tree). Resolved server-side by `cf_item_repository.list_items_by_subject` / `count_items_by_subject` via the JSONB containment query `subject_uri @> '[{"identifier": ...}]'` (GIN-indexed: `ix_cf_items_subject_uri_gin`). Each row links to the item in its own document's tree. Scope notes: **within-tenant only** (a subject is tenant-owned; no cross-tenant/private gating); items that reference the subject only via the plain `subject` string (no `subjectURI`) are **not** matched; the reusable `fragments/subject_items.html` partial backs both the inline SSR and the fragment route (and is intended for reuse by a future search results list). The section is **not** shown in the tree right pane (the pane is document-scoped). Other lookups (CFItemType/Concept/License) do not yet have an equivalent reverse list.
+
 ### CFRubric
 
 When `/uri/{uuid}` resolves to a CFRubric, show the rubric detail along with Criteria/Levels in a table:

src/locales/en.json

@@ -65,6 +65,9 @@
     "related_other_institution": "Other institution ↗",
     "related_other_institution_in": "Other institution ↩",
     "incoming_refs_label": "Referenced by (other institutions)",
+    "subject_items_label": "Items setting this subject",
+    "subject_items_count": "{count} total",
+    "show_more": "Show more",
     "related_external": "External",
     "f_subject": "Subject",
     "f_subject_uri": "Subject URI",

src/locales/ja.json

@@ -65,6 +65,9 @@
     "related_other_institution": "他機関 ↗",
     "related_other_institution_in": "他機関 ↩",
     "incoming_refs_label": "参照元（他機関）",
+    "subject_items_label": "この分野を設定している項目",
+    "subject_items_count": "全 {count} 件",
+    "show_more": "もっと見る",
     "related_external": "外部",
     "f_subject": "教科",
     "f_subject_uri": "教科 URI",

src/repositories/cf_item_repository.py

@@ -1,13 +1,23 @@
 import uuid
 
-from sqlalchemy import select
+from sqlalchemy import cast, func, select
+from sqlalchemy.dialects.postgresql import JSONB
 from sqlalchemy.ext.asyncio import AsyncSession
 from sqlalchemy.orm import joinedload
 
 from src.models.cf_document import CFDocument
 from src.models.cf_item import CFItem
 
 
+def _subject_uri_contains(subject_identifier: str):
+    """JSONB containment predicate: subject_uri @> '[{"identifier": <id>}]'.
+
+    The operand is cast to JSONB explicitly so the GIN index
+    (ix_cf_items_subject_uri_gin, jsonb_path_ops) is used rather than a seq scan.
+    """
+    return CFItem.subject_uri.contains(cast([{"identifier": subject_identifier}], JSONB))
+
+
 async def map_identifiers_to_documents(
     session: AsyncSession,
     tenant_id: uuid.UUID,
@@ -95,3 +105,65 @@ async def get_cf_item_by_identifier(
         .where(CFItem.tenant_id == tenant_id, CFItem.identifier == identifier)
     )
     return result.scalar_one_or_none()
+
+
+async def list_items_by_subject(
+    session: AsyncSession,
+    tenant_id: uuid.UUID,
+    subject_identifier: str,
+    *,
+    offset: int = 0,
+    limit: int = 20,
+) -> list[dict]:
+    """CFItems in this tenant whose ``subject_uri`` references the given subject.
+
+    Reverse lookup for the CFSubject detail page ("items setting this subject").
+    Matches via JSONB containment ``subject_uri @> '[{"identifier": <id>}]'``
+    (GIN-indexed). Tenant-scoped. Ordered by human_coding_scheme → full_statement
+    → identifier for a stable offset-pagination boundary. Returns
+    ``[{identifier, human_coding_scheme, full_statement, doc_identifier, doc_title}]``.
+    """
+    rows = await session.execute(
+        select(
+            CFItem.identifier,
+            CFItem.human_coding_scheme,
+            CFItem.full_statement,
+            CFDocument.identifier,
+            CFDocument.title,
+        )
+        .join(CFDocument, CFItem.cf_document_id == CFDocument.id)
+        .where(CFItem.tenant_id == tenant_id, _subject_uri_contains(subject_identifier))
+        .order_by(
+            CFItem.human_coding_scheme.nullslast(),
+            CFItem.full_statement,
+            CFItem.identifier,
+        )
+        .offset(offset)
+        .limit(limit)
+    )
+    return [
+        {
+            "identifier": str(item_ident),
+            "human_coding_scheme": hcs,
+            "full_statement": full_statement,
+            "doc_identifier": str(doc_ident),
+            "doc_title": doc_title,
+        }
+        for item_ident, hcs, full_statement, doc_ident, doc_title in rows.all()
+    ]
+
+
+async def count_items_by_subject(
+    session: AsyncSession,
+    tenant_id: uuid.UUID,
+    subject_identifier: str,
+) -> int:
+    """Total CFItems in this tenant referencing the given subject (for the count
+    label). Call once on the SSR page; the "load more" fragment derives has_more
+    from a limit+1 fetch instead of recounting."""
+    result = await session.execute(
+        select(func.count())
+        .select_from(CFItem)
+        .where(CFItem.tenant_id == tenant_id, _subject_uri_contains(subject_identifier))
+    )
+    return int(result.scalar_one())

src/routers/web.py

@@ -63,6 +63,10 @@ def _uri_other_tenant(uri: str | None, current_tenant_id) -> bool:
 CACHE_CONTROL = "public, max-age=3600"
 CACHE_CONTROL_FRAGMENT = "public, max-age=86400"
 
+# Page size for the CFSubject "items setting this subject" reverse-lookup list
+# (inline top-N on the subject page + "load more" HTMX pagination).
+SUBJECT_ITEMS_PAGE = 20
+
 # Map UriResult.resource_type to the CASE v1.1 API path segment.
 # Resource types without an individual API endpoint (CFRubricCriterion,
 # CFRubricCriterionLevel — nested only inside CFRubrics) are absent.
@@ -405,7 +409,14 @@ async def _incoming_refs(session: AsyncSession, tenant_id, item) -> list[dict]:
 
 
 async def _detail_extras(
-    session: AsyncSession, tenant_id, resource_type: str, resource, doc=None, tree_index=None
+    session: AsyncSession,
+    tenant_id,
+    resource_type: str,
+    resource,
+    doc=None,
+    tree_index=None,
+    *,
+    include_subject_items: bool = True,
 ) -> dict:
     """Extra context the resource-detail card needs beyond the resource itself:
     rubrics (CFDocument), referring criteria + related groupings (CFItem).
@@ -446,6 +457,15 @@ async def _detail_extras(
     # this item's node_uri ("referenced by other institutions"). Private origins
     # are excluded by `_incoming_refs` (case A — existence + count hidden).
     incoming_refs: list[dict] = []
+    # CFSubject reverse lookup: items in THIS tenant that set this subject (first
+    # page + total + has_more). Within-tenant only (a subject is tenant-owned).
+    subject_items: dict = {
+        "rows": [],
+        "total": 0,
+        "has_more": False,
+        "next_offset": 0,
+        "limit": SUBJECT_ITEMS_PAGE,
+    }
     if resource_type == "CFDocument":
         rubrics = await cf_rubric_repository.list_by_document(session, resource.id)
     elif resource_type == "CFAssociation":
@@ -547,6 +567,23 @@ async def _detail_extras(
                 related_other_tenant = await _resolve_cross_tenant(session, tenant_id, unresolved)
         hierarchy_upper, hierarchy_lower = await _cross_doc_hierarchy(session, tenant_id, resource, doc)
         incoming_refs = await _incoming_refs(session, tenant_id, resource)
+    elif resource_type == "CFSubject" and include_subject_items:
+        # Only the standalone /uri/ page lists "items setting this subject". The
+        # tree right pane is document-scoped, so pane callers pass
+        # include_subject_items=False — keeping it hidden there AND skipping the
+        # (potentially large) reverse-lookup query.
+        sid = str(resource.identifier)
+        rows = await cf_item_repository.list_items_by_subject(
+            session, tenant_id, sid, offset=0, limit=SUBJECT_ITEMS_PAGE
+        )
+        total = await cf_item_repository.count_items_by_subject(session, tenant_id, sid)
+        subject_items = {
+            "rows": rows,
+            "total": total,
+            "has_more": total > len(rows),
+            "next_offset": len(rows),
+            "limit": SUBJECT_ITEMS_PAGE,
+        }
     return {
         "rubrics": rubrics,
         "referring_criteria": referring_criteria,
@@ -560,6 +597,7 @@ async def _detail_extras(
         "hierarchy_upper": hierarchy_upper,
         "hierarchy_lower": hierarchy_lower,
         "incoming_refs": incoming_refs,
+        "subject_items": subject_items,
     }
 
 
@@ -577,6 +615,7 @@ async def _detail_extras(
     "hierarchy_upper",
     "hierarchy_lower",
     "incoming_refs",
+    "subject_items",
 )
 
 
@@ -801,6 +840,9 @@ async def _render_tree_page(
         "hierarchy_upper": hierarchy_upper,
         "hierarchy_lower": hierarchy_lower,
         "incoming_refs": incoming_refs,
+        # The tree pane is document-scoped; a subject's cross-document "items
+        # setting this subject" list is shown only on the standalone /uri/ page.
+        "subject_items": {"rows": [], "total": 0, "has_more": False, "next_offset": 0, "limit": SUBJECT_ITEMS_PAGE},
     }
     ctx = _detail_pane_context(
         pane_extras,
@@ -965,7 +1007,9 @@ async def _pane_fragment_response(
     """Render the shared full-detail card as a right-pane HTMX fragment."""
     lang = _get_lang(request)
     t = get_translator(lang)
-    extras = await _detail_extras(session, tenant_obj.id, resource_type, resource, doc)
+    # in_pane: the tree pane is document-scoped, so suppress the CFSubject
+    # "items setting this subject" reverse list here (don't compute or render it).
+    extras = await _detail_extras(session, tenant_obj.id, resource_type, resource, doc, include_subject_items=False)
     # in_pane=True → the redundant "Show in tree" link is hidden by the partial.
     ctx = _detail_pane_context(
         extras,
@@ -1084,6 +1128,58 @@ async def children_fragment(
     return response
 
 
+@router.get(
+    "/{tenant}/subject/{subject_id}/items",
+    response_class=HTMLResponse,
+)
+async def subject_items_fragment(
+    tenant: str,
+    subject_id: str,
+    request: Request,
+    offset: int = 0,
+    limit: int = SUBJECT_ITEMS_PAGE,
+    session: AsyncSession = Depends(get_session),
+) -> HTMLResponse:
+    """HTMX fragment: the next page of "items setting this subject", appended on
+    the CFSubject detail page ("load more"). Mirrors the tree's lazy-load shape —
+    returns the same `subject_items.html` markup (rows + a self-perpetuating
+    button), so each click swaps the button for the next page + a fresh button.
+    Within-tenant only. has_more is derived from a limit+1 fetch (no recount)."""
+    t = get_translator(_get_lang(request))
+    tenant_obj = await tenant_service.resolve_tenant(session, tenant)
+    if tenant_obj is None:
+        return _error_fragment(404, t("error_tenant_not_found"))
+
+    subject_uuid = _parse_uuid(subject_id)
+    if subject_uuid is None:
+        return _error_fragment(400, t("error_bad_request"))
+    # The id must resolve to a CFSubject in THIS tenant (same "validate the
+    # target" invariant as children_fragment) — never drive this for arbitrary ids.
+    result = await uri_service.find_resource_by_identifier(session, tenant_obj.id, subject_uuid)
+    if result is None or result.resource_type != "CFSubject":
+        return _error_fragment(404, t("error_not_found"))
+
+    offset = max(0, offset)
+    limit = max(1, min(limit, SUBJECT_ITEMS_PAGE))
+    rows = await cf_item_repository.list_items_by_subject(
+        session, tenant_obj.id, str(subject_uuid), offset=offset, limit=limit + 1
+    )
+    has_more = len(rows) > limit
+    rows = rows[:limit]
+    ctx = {
+        "rows": rows,
+        "next_offset": offset + len(rows),
+        "limit": limit,
+        "has_more": has_more,
+        "subject_id": str(subject_uuid),
+        "tenant_url": _tenant_url_segment(tenant, tenant_obj),
+        "t": t,
+    }
+    response = templates.TemplateResponse(request, "fragments/subject_items.html", ctx)
+    response.headers["Cache-Control"] = CACHE_CONTROL_FRAGMENT
+    return response
+
+
 @router.get(
     "/{tenant}/cftree/doc/{doc_id}/document",
     response_class=HTMLResponse,

src/templates/fragments/resource_detail.html

@@ -952,6 +952,22 @@ <h3 class="text-sm font-semibold text-stone-600 mb-2">{{ t("rubric_levels") }}</
             {% if resource.license_text is defined %}{{ optional_field(t("f_license_text"), resource.license_text) }}{% endif %}
         </dl>
 
+        {# CFSubject reverse lookup: items in this tenant that set this subject. #}
+        {% if resource_type == "CFSubject" and subject_items.rows %}
+        {% call section(t("subject_items_label")) %}
+            <div>
+                <dd class="text-gray-800">
+                    <p class="text-xs text-stone-400 mb-2">{{ t("subject_items_count", count=subject_items.total|string) }}</p>
+                    <ul class="ml-4 space-y-1">
+                        {% with rows=subject_items.rows, next_offset=subject_items.next_offset, limit=subject_items.limit, has_more=subject_items.has_more, subject_id=resource.identifier %}
+                        {% include "fragments/subject_items.html" %}
+                        {% endwith %}
+                    </ul>
+                </dd>
+            </div>
+        {% endcall %}
+        {% endif %}
+
         {% call section(t("sec_technical"), muted=true) %}
             {{ code_field(t("f_identifier"), resource.identifier) }}
             {{ uri_field(t("f_uri"), resource.uri) }}

src/templates/fragments/subject_items.html

@@ -0,0 +1,23 @@
+{# Reusable list fragment: CFItems setting a subject.
+   Used both as an SSR include on the CFSubject detail card and as the response
+   of the /{tenant}/subject/{id}/items "load more" route (same markup, like
+   tree_nodes.html). Context: rows, next_offset, limit, has_more, subject_id,
+   tenant_url, t. Each row links to the item in its own document's tree (a
+   subject has no document, so always the cross-document deep-link form). #}
+{% for row in rows %}
+<li>
+    <a href="/{{ tenant_url }}/cftree/doc/{{ row.doc_identifier }}/item/{{ row.identifier }}"
+       class="text-violet-600 hover:text-violet-800 text-sm transition-colors"
+       {% if row.doc_title %}title="{{ row.doc_title }}"{% endif %}>
+        {% if row.human_coding_scheme %}<span class="font-medium">{{ row.human_coding_scheme }}</span> {% endif %}{{ row.full_statement[:100] }}{% if row.full_statement and row.full_statement|length > 100 %}…{% endif %}
+    </a>
+</li>
+{% endfor %}
+{% if has_more %}
+<li>
+    <button type="button"
+            hx-get="/{{ tenant_url }}/subject/{{ subject_id }}/items?offset={{ next_offset }}&limit={{ limit }}"
+            hx-target="closest li" hx-swap="outerHTML"
+            class="text-xs text-violet-600 hover:text-violet-800 underline transition-colors">{{ t("show_more") }}</button>
+</li>
+{% endif %}