The demo UI: one static page (index.html) and one Lambda handler
(handler.py) that serves it and answers POST /api/ask. No framework, no
build step; the page is hand-written HTML/CSS/JS targeting WCAG 2.2 AA (labels,
visible focus, aria-live results, 24px-minimum targets, works on a phone).
a11y.py is a pure-Python structural accessibility gate (page language,
labeled controls, heading order, link text, zoom not disabled, target size). It
runs in CI and as make a11y; a blocking pa11y/axe pass cross-checks the
parts a static analysis cannot (computed contrast, ARIA semantics). Neither
replaces a manual screen-reader walkthrough, recorded in the model card.
The page carries the three disclosures CLAUDE.md requires: the "reference implementation" banner, the will-not-do list, and the "based on policies published as of " line (static in the header, per-answer from the API). The footer states that questions are never stored.
Deploy with ./infra/deploy.sh (see ADR 0004 for the architecture and the
abuse/cost guards). Try it locally without deploying:
uv run python -m assistant.cli "How much is the senior fare on SBMTD?"API shape:
POST /api/ask
{"question": "Does it cover my spouse too?",
"history": [{"q": "<prior question>", "a": "<prior answer>"}]}
200 → {"answer": "...", "kind": "answered", "language": "en",
"as_of_date": "2026-06-12", "citations": [{"agency": "MST", ...}]}
history is optional (omit it for a one-shot question). The client holds the
conversation; the server stores nothing. Up to the last three turns are used to
resolve follow-up references, and answers are deterministically cached per
container keyed on the question and its history.
kind is the same trace field the eval harness records: answered,
refused_input, refused_no_support, or answered_guarded.