Filter values are CASE-SENSITIVE. Use exact casing:
- document_type: 'Proposed Rule', 'Rule', 'Notice', 'Supporting & Related Material', 'Other'
- Lowercase values silently return 0 results (no error)

Key parameters:
- search_term: full-text match, including attachment text. Results
  follow sort (newest first by default), not relevance, so an unquoted
  multi-word term puts loosely matching recent documents first; quote
  a phrase ('"Pay Equity and Transparency"') to match it exactly.
- agency_id: FAR, DARS, GSA, SBA, OFPP, DOD, NASA, VA, etc.
  Comma-separate for multiple agencies ('FAR,GSA'). Empty string is rejected.
- docket_id: e.g., 'FAR-2023-0008' for a specific FAR case
- within_comment_period: True to find documents currently accepting
  comments. False is NOT supported by the API (it 400s); omit the
  parameter instead to search regardless of comment status.
- posted_date_ge/le: YYYY-MM-DD format (calendar-checked)
- comment_end_date_ge/le: YYYY-MM-DD format

Response meta.facets gives the top counts by document type, agency,
and comment period status; a facet the query filtered on is left out,
because the API counts it site-wide. meta.totalElements is the full
match count.

Comment deadlines: attributes.commentDeadlineEastern is the date reported
by Regulations.gov metadata in Eastern time (e.g. 'Oct 22, 2026 11:59 PM ET'). The raw
commentEndDateUtc is the provider UTC instant. commentDeadlineVerification
links to the notice/docket: read DATES, eligibility, and later extensions
before treating this metadata date as controlling. If unavailable, the
controlling deadline cannot be established.

Page size: 5-100. page_number: 1-40. The API serves 40 pages; when more
records match, page_limit_note (and truncated=true on page 40) says how
many are out of reach. Split the query into posted_date_ge/le windows.

sort: '-postedDate' (newest first, default), 'postedDate', '-commentEndDate',
'lastModifiedDate', 'title', 'documentId'. Comma-separate for
multi-field sorts ('lastModifiedDate,documentId').