test(e2e): briefing and Ask in the browser; fix an outline race

The seeded world gains a cached briefing and two cached answers for
SatNav. New browser tests: the briefing's links and outline entries, a
suggested question echoed then answered with a cite, Enter sends while
Shift+Enter doesn't, a missing model says busy, the phone sheet opens and
closes on Escape with focus back on its button, and the lightbox asks about
its figure. Fixed on the way: the section observer could override the last
outline entry at the bottom of the page.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

app/static/paper.js

@@ -247,8 +247,18 @@
     });
   }
 
+  function atBottom() {
+    return window.innerHeight + window.scrollY >= document.documentElement.scrollHeight - 4;
+  }
+  function lastVisibleLink() {
+    var shown = Array.prototype.filter.call(links, function (a) { return !a.hidden; });
+    return shown[shown.length - 1];
+  }
+
   if (links.length && 'IntersectionObserver' in window) {
     var observer = new IntersectionObserver(function (entries) {
+      /* At the bottom the last section wins, whatever crosses the band. */
+      if (atBottom()) { markActive(lastVisibleLink().getAttribute('data-sec')); return; }
       entries.forEach(function (en) { if (en.isIntersecting) markActive(en.target.id); });
     }, { rootMargin: '-20% 0px -70% 0px' });
     /* A short last section never reaches that band, so at the bottom of the
@@ -259,10 +269,7 @@
       ticking = true;
       requestAnimationFrame(function () {
         ticking = false;
-        var doc = document.documentElement;
-        if (window.innerHeight + window.scrollY >= doc.scrollHeight - 4) {
-          markActive(links[links.length - 1].getAttribute('data-sec'));
-        }
+        if (atBottom()) markActive(lastVisibleLink().getAttribute('data-sec'));
       });
     }, { passive: true });
     function watch() {

scripts/seed_e2e.py

@@ -25,7 +25,7 @@ values in .env.local can't leak in (load_dotenv never overrides a set name):
     DB_PATH=/tmp/e2e.db METADATA_SIDECAR_PATH=/tmp/e2e_sidecar.sqlite \\
     RESEARCHIT_ENV=test ARXIV_HTML_BASE=http://127.0.0.1:8799 \\
     TURSO_URL= TURSO_DB_TOKEN= QDRANT_URL= GROQ_API_KEY= TURSO_SYNC_DISABLED=1 \\
-    PAPER_PAGE_V2=on FIGURES=on PAPER_SOURCES=on PORT=7861 python run.py
+    PAPER_PAGE_V2=on FIGURES=on PAPER_SOURCES=on BRIEFING=on ASK=on PORT=7861 python run.py
 """
 from __future__ import annotations
 
@@ -122,8 +122,31 @@ def build_site(site: Path, parsed: dict) -> int:
     return n
 
 
+SATNAV_BRIEFING = {
+    "things": [
+        {"lead": "118K episodes from satellite imagery.", "text": "Built across 59 scenes in 18 cities.",
+         "anchor": "abstract", "label": "Abstract"},
+        {"lead": "City-scale navigation is still hard.", "text": "Agents struggle on long routes.",
+         "anchor": "S1.p2", "label": "§1"},
+        {"lead": "Memory matters.", "text": "Removing long-term memory hurts.", "anchor": "S4.SS1.p1", "label": "§4.1"},
+    ],
+    "how": [{"name": "Pair the maps", "text": "Satellite images aligned with map data."},
+            {"name": "Write the tasks", "text": "Routes become instructions."},
+            {"name": "Navigate", "text": "The agent picks one of four actions."}],
+    "use": "Teams training drones that follow spoken directions.",
+    "dropped": [],
+}
+SATNAV_ANSWERS = {
+    "limits": {"kind": "answer", "answer": "The authors list three limitations, starting with discrete moves at a fixed altitude.",
+               "quotes": [], "cites": [{"anchor": "S6.p1", "label": "§6"}], "dropped": {"quotes": 0, "cites": 0}},
+    "new": {"kind": "answer", "answer": "A navigation benchmark built from satellite images instead of 3D models.",
+            "quotes": [], "cites": [{"anchor": "S1.p4", "label": "§1"}], "dropped": {"quotes": 0, "cites": 0}},
+}
+
+
 async def seed_db(db_path: Path, parsed: dict) -> None:
-    from app import config, db, groq_svc, paper_source_svc
+    import json as _json
+    from app import ask_svc, briefing_svc, config, db, groq_svc, paper_source_svc
     config.DB_PATH = db.DB_PATH = str(db_path)
     await db.init_db()
     for aid in PAPERS:
@@ -133,6 +156,23 @@ async def seed_db(db_path: Path, parsed: dict) -> None:
     abstracts[MATHS_ID] = MATHS_ABSTRACT
     for aid, text in SUMMARIES.items():
         await db.save_explanation(groq_svc.explain_cache_key(aid, abstracts[aid]), aid, text, "seed")
+    # A cached briefing and two cached suggested answers for SatNav, under the
+    # keys the server will compute with the default model chain.
+    version = parsed["2609.31507"].version
+    import aiosqlite
+    async with aiosqlite.connect(config.DB_PATH) as conn:
+        await conn.execute(
+            "INSERT INTO paper_briefings (cache_key, arxiv_id, status, briefing_json, provider, model, prompt_version) "
+            "VALUES (?, ?, 'ok', ?, 'seed', 'seed', ?)",
+            (briefing_svc.cache_key("2609.31507", version), "2609.31507", _json.dumps(SATNAV_BRIEFING),
+             briefing_svc.PROMPT_VERSION))
+        for key, answer in SATNAV_ANSWERS.items():
+            await conn.execute(
+                "INSERT INTO paper_answers (cache_key, arxiv_id, question_key, answer_json, model, prompt_version) "
+                "VALUES (?, ?, ?, ?, 'seed', ?)",
+                (ask_svc.cache_key("2609.31507", version, key), "2609.31507", key, _json.dumps(answer),
+                 ask_svc.PROMPT_VERSION))
+        await conn.commit()
 
 
 def main(argv=None) -> int:

tests/test_e2e_paper.py

@@ -124,7 +124,7 @@ def test_the_outline_marks_the_section_in_view(satnav):
     # At the very bottom the last section is the one in view, however short.
     satnav.evaluate("window.scrollTo(0, document.documentElement.scrollHeight)")
     satnav.wait_for_timeout(400)
-    last = satnav.evaluate("[...document.querySelectorAll('.outline nav a')].at(-1).dataset.sec")
+    last = satnav.evaluate("[...document.querySelectorAll('.outline nav a')].filter(a => !a.hidden).at(-1).dataset.sec")
     assert active() == [last]
 
 
@@ -187,3 +187,71 @@ def test_a_paper_without_arxiv_html_shows_no_figure_sections(browser):
     ctx, page = open_page(browser, f"/p/{MATHS}")
     assert page.locator("#sec-fig").count() == 0 and page.locator("#sec-figs").count() == 0
     ctx.close()
+
+
+# ── briefing and Ask (server started with BRIEFING=on ASK=on) ────────────────
+
+def _needs(page, selector, switch):
+    if page.locator(selector).count() == 0:
+        pytest.skip(f"server not started with {switch}=on")
+
+
+def test_the_briefing_arrives_with_links_to_each_passage(satnav):
+    _needs(satnav, ".brief-slot, #sec-things", "BRIEFING")
+    satnav.wait_for_selector("#sec-things li")
+    assert satnav.locator("#sec-things li").count() == 3
+    href = satnav.get_attribute("#sec-things a.src", "href")
+    assert href == f"https://arxiv.org/html/{SATNAV}v1#abstract"
+    assert satnav.locator("#sec-how li").count() == 3 and satnav.is_visible("#sec-use")
+    # The outline's briefing links appear once the sections exist.
+    satnav.wait_for_function("!document.querySelector('.outline a[data-sec=\"sec-things\"]').hidden")
+
+
+def test_a_suggested_question_is_echoed_then_answered_with_a_cite(satnav):
+    _needs(satnav, "#chat", "ASK")
+    satnav.click('[data-ask-key="limits"]')
+    satnav.wait_for_selector("#chat-log .msg-user")
+    assert satnav.inner_text("#chat-log .msg-user") == "What are the limitations?"
+    satnav.wait_for_selector("#chat-log .cite")
+    assert "three limitations" in satnav.inner_text("#chat-log")
+    assert satnav.get_attribute("#chat-log .cite", "href") == f"https://arxiv.org/html/{SATNAV}v1#S6.p1"
+    assert satnav.locator('[data-ask-key="limits"]').count() == 0      # the chip is used up
+
+
+def test_a_typed_question_sends_on_enter_and_a_missing_model_says_busy(satnav):
+    _needs(satnav, "#chat", "ASK")
+    satnav.fill("#chat-input", "How many cities are there?")
+    satnav.press("#chat-input", "Enter")
+    satnav.wait_for_selector("#chat-log .msg-bot >> nth=1")
+    assert "busy right now" in satnav.inner_text("#chat-log")
+    assert satnav.input_value("#chat-input") == ""
+
+
+def test_shift_enter_starts_a_new_line_instead_of_sending(satnav):
+    _needs(satnav, "#chat", "ASK")
+    satnav.fill("#chat-input", "First line")
+    satnav.press("#chat-input", "Shift+Enter")
+    satnav.wait_for_timeout(300)
+    assert satnav.locator("#chat-log .msg-user").count() == 0
+
+
+def test_on_a_phone_ask_opens_as_a_sheet_and_closes_on_escape(browser):
+    ctx, page = open_page(browser, f"/p/{SATNAV}", width=390, height=844)
+    _needs(page, "#chat", "ASK")
+    assert not page.is_visible("#chat") and page.is_visible(".ask-fab")
+    page.click(".ask-fab")
+    assert page.is_visible("#chat") and page.evaluate("document.activeElement.id") == "chat-input"
+    page.keyboard.press("Escape")
+    assert not page.is_visible("#chat")
+    assert page.evaluate("document.activeElement.classList.contains('ask-fab')")
+    assert page.errors == []
+    ctx.close()
+
+
+def test_ask_about_this_figure_asks_in_the_panel(satnav):
+    _needs(satnav, "#chat", "ASK")
+    satnav.click("#sec-fig [data-fig]")
+    satnav.wait_for_function("document.getElementById('lb').open")
+    satnav.click("#lb-ask")
+    satnav.wait_for_selector("#chat-log .msg-user")
+    assert satnav.inner_text("#chat-log .msg-user") == "Explain figure 1"