docs/source/_templates/docs-sidebar.html

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{# Start the sidebar from the deepest captioned section the page lives under:
   - user-guide/* (any version, including the index itself) always anchors
     at user-guide/index (depth 1) and nests each version's own captioned
     groups inside that version's accordion (see user_guide_sidebar_html in
     conf.py), so the same version-accordion tree stays visible and stable
     across every User Guide page — only the "current" highlighting and
     which accordion is expanded change.
   - contributor-guide/* lives under contributor-guide/index.md, so start at depth 1
   - root and orphan pages (search, genindex) fall back to the global toctree (depth 0).
   user_guide_versioned additionally requires a real depth-1 ancestor to
   exist, so orphan pages under user-guide/ (not reachable from any
   toctree) fall through to the depth-0 global fallback below instead of
   crashing generate_toctree_html. #}
{% set user_guide_versioned = pagename.startswith("user-guide/") and not suppress_sidebar_toctree(startdepth=1, includehidden=True) %}
{% if user_guide_versioned %}
{% elif not suppress_sidebar_toctree(startdepth=1, includehidden=True) %}
  {% set sidebar_startdepth = 1 %}
{% else %}
  {% set sidebar_startdepth = 0 %}
{% endif %}
<nav class="bd-links" id="bd-docs-nav" aria-label="Main navigation">
  <div class="bd-toc-item active">
    {% if user_guide_versioned %}
      {{ user_guide_sidebar_html() }}
    {% else %}
      {{ generate_toctree_html("sidebar", startdepth=sidebar_startdepth, maxdepth=4, collapse=False, includehidden=True, titles_only=True) }}
    {% endif %}
  </div>
</nav>