fix(web): keep the navbar stuck to the top — drop the body height cap on the sticky range

tests/e2e/test_sticky_navbar.py

@@ -0,0 +1,339 @@
+"""Phase 60 E2E (Playwright): the navbar stays stuck to the top of the
+screen at every scroll position — and the short-page layout is intact.
+
+Source: ``TODO.md`` L3 — "The navbar disappears when you scroll down,
+should stay stuck to the top of the screen" (no user story file —
+TODO-derived phase).
+Run in isolation (DB must be up: ``podman compose up -d db``):
+
+    uv run pytest tests/e2e/test_sticky_navbar.py -v --no-cov
+
+Mechanism under test (owner-locked A1/A2, roadmap confirmation
+2026-08-31): the sticky rule was always there — ``.app-header`` (every
+page) and the viewer's two-row ``.doc-header`` (``/document.html``)
+both carry ``position: sticky; top: 0``. What broke it: ``body {
+height: 100% }`` pinned the body box to exactly one viewport, and a
+sticky element may only travel inside its containing block — so after
+~1 viewport of scroll the header un-pinned and scrolled away with the
+body. The CSS-only fix (task 01) dropped ``height`` from the ``body``
+rule (``html`` keeps it); the body's ``min-height: 100dvh`` still drives
+the short-page stretch. This suite proves the BROWSER behavior:
+
+* on a long page the header's bounding-box top is 0 at a mid-page
+  scroll AND at the very bottom (the pre-fix value at the bottom was
+  off-screen negative — ~−1264px in the audit's 2000px repro);
+* the document stays the scroll container (phase 52 no-inner-scroller
+  contract) — the fix added no scroller, it only let the body grow;
+* the short-page layout is EXACTLY as it was: body stretched to the
+  viewport, footer pinned to the viewport bottom, the phase-52
+  pinned composer (``position: sticky; bottom: env(safe-area-inset-
+  bottom)``) resting in its in-flow slot above the footer.
+
+Seeding (A3): the long-scroll surfaces are the seeded Sources table
+(``tests/fixtures/docs/`` — 13 docs, same harness as the phase-10/26
+suites) PLUS a generated scratch dir the module writes (``gen/``: 40
+short unique docs + one ``doc-long.md`` with a ~40,000-char body).
+``import_sources`` runs in a worker thread against the deterministic
+mock embeddings server (the ``test_document_viewer.py`` pattern) — no
+real LLM is involved.
+
+Test → story mapping (Playwright Mapping Rule):
+1. ``test_app_header_stuck_at_top_on_sources``
+2. ``test_doc_header_stuck_at_top_on_long_document``
+3. ``test_short_page_stretch_and_resting_composer_intact``
+"""
+from __future__ import annotations
+
+import asyncio
+from collections.abc import Iterator
+from pathlib import Path
+from threading import Thread
+from typing import Any
+
+import httpx
+import pytest
+from playwright.sync_api import Page, expect
+from sqlalchemy import text
+
+from app.config import Settings
+from app.db import SessionLocal
+from app.rag.importer import ImportSummary, import_sources
+from app.rag.llm import LLMClient
+from e2e.auth_helpers import login
+
+REPO = Path(__file__).resolve().parents[2]
+FIXTURES = REPO / "tests" / "fixtures" / "docs"
+
+#: The conftest ``page`` fixture's viewport (1280×800).
+VIEWPORT_W = 1280
+VIEWPORT_H = 800
+
+#: Tolerance for "stuck at the top" / "pinned to the viewport edge":
+#: the measured positions are sub-pixel stable (0 in the audit), so the
+#: slack is rounding headroom only.
+TOP_TOL_PX = 1
+
+#: Phase-52 resting-composer constants (test_pinned_composer.py): the
+#: band below a resting composer may only be chrome — the footer's own
+#: measured height plus the flow padding of the settled slot — and the
+#: box must sit in the lower part of the screen.
+BOTTOM_SLACK_PX = 56
+LOWER_PART = 0.8
+
+#: Seeding: 13 fixture docs (the A9 family, ``.hidden/`` skipped) + the
+#: generated scratch docs.
+SHORT_DOC_COUNT = 40
+LONG_DOC_BODY_CHARS = 40_000
+TOTAL_DOCS = 13 + SHORT_DOC_COUNT + 1  # + the one long doc
+
+
+# ---------------------------------------------------------------------------
+# KB seeding (same pattern as the phase 10/26/52 story suites)
+# ---------------------------------------------------------------------------
+
+
+def _write_generated_docs(base: Path) -> Path:
+    """The scratch source dir: ``gen/doc-001.md`` … ``gen/doc-040.md``
+    (one-line bodies, unique titles) plus ``gen/doc-long.md`` with a
+    ~40,000-char body (deterministic numbered paragraphs — real
+    scrollable content, no injected DOM)."""
+    gen = base / "gen"
+    gen.mkdir(parents=True, exist_ok=True)
+    for i in range(1, SHORT_DOC_COUNT + 1):
+        (gen / f"doc-{i:03d}.md").write_text(
+            f"# Sticky probe {i:03d}\n\nShort body line for probe {i:03d}.\n",
+            encoding="utf-8",
+        )
+    paragraphs: list[str] = []
+    n = 0
+    while sum(len(p) for p in paragraphs) < LONG_DOC_BODY_CHARS:
+        n += 1
+        paragraphs.append(
+            f"Paragraph {n:04d}: the quick brown fox jumps over the "
+            "lazy dog near the homelab rack."
+        )
+    (gen / "doc-long.md").write_text(
+        "# Sticky long document\n\n" + "\n\n".join(paragraphs) + "\n",
+        encoding="utf-8",
+    )
+    return gen
+
+
+async def _import_dirs(mock_port: int, dirs: list[Path]) -> ImportSummary:
+    kwargs: dict[str, Any] = {"_env_file": None, "llm_base_url": f"http://127.0.0.1:{mock_port}/v1"}
+    settings = Settings(**kwargs)  # pyright: ignore[reportCallIssue]
+    return await import_sources(dirs, LLMClient(settings))
+
+
+def _run_in_thread(coro: Any) -> Any:
+    """Run a coroutine on a worker thread.
+
+    Playwright's sync API keeps an asyncio loop running on the test thread,
+    so ``asyncio.run`` cannot be called directly from a test body.
+    """
+    box: dict[str, Any] = {}
+
+    def runner() -> None:
+        try:
+            box["value"] = asyncio.run(coro)
+        except BaseException as e:  # noqa: BLE001 — re-raised on the test thread
+            box["error"] = e
+
+    t = Thread(target=runner)
+    t.start()
+    t.join()
+    if "error" in box:
+        raise box["error"]
+    return box["value"]
+
+
+def _reset_db(mock_port: int, dirs: list[Path] | None) -> ImportSummary | None:
+    """Truncate the KB (and query log), then optionally re-import."""
+    with SessionLocal() as db:
+        db.execute(text("TRUNCATE chunks, documents, query_log"))
+        db.commit()
+    if not dirs:
+        return None
+    return _run_in_thread(_import_dirs(mock_port, dirs))
+
+
+@pytest.fixture(scope="module")
+def kb_db_ready(app_url: str) -> None:
+    """Module-scoped twin of conftest's ``db_ready`` (conftest's one is
+    function-scoped and cannot back a module-scoped fixture)."""
+    body = httpx.get(f"{app_url}/api/health", timeout=5).json()
+    if body["db"] != "up":
+        pytest.skip("Postgres not reachable — run `podman compose up -d db` first")
+
+
+@pytest.fixture(scope="module")
+def seeded_kb(
+    mock_llm: int, kb_db_ready: None, tmp_path_factory: pytest.TempPathFactory
+) -> Iterator[None]:
+    """A fresh KB: the 13 fixture docs + the generated scratch dir,
+    imported once for the whole module (truncated again on teardown)."""
+    gen = _write_generated_docs(tmp_path_factory.mktemp("sticky_navbar"))
+    summary = _reset_db(mock_llm, [FIXTURES, gen])
+    assert summary is not None and summary.added == TOTAL_DOCS, (
+        f"expected {TOTAL_DOCS} added docs, got {summary.added if summary else None}"
+    )
+    yield
+    _reset_db(mock_llm, None)
+
+
+# ---------------------------------------------------------------------------
+# Measurement helpers
+# ---------------------------------------------------------------------------
+
+
+def _assert_top_is_zero(page: Page, selector: str) -> None:
+    """The element's bounding-box top is the viewport top (± TOP_TOL_PX).
+
+    ``bounding_box`` is viewport-relative and never scrolls the page
+    itself, so this is exactly "where the bar sits where the user left
+    it" — the TODO's question. Pre-fix, the header's top here was a
+    large NEGATIVE number (scrolled away with the capped body).
+    """
+    box = page.locator(selector).bounding_box()
+    assert box is not None, f"{selector} must be rendered (no bounding box)"
+    # Playwright's bounding box is x/y/width/height — top == y.
+    assert abs(box["y"]) <= TOP_TOL_PX, (
+        f"{selector} is not stuck to the top: rect top={box['y']:.2f} "
+        f"(want 0 ±{TOP_TOL_PX}) at scrollY={page.evaluate('() => window.scrollY'):.0f}"
+    )
+
+
+# ---------------------------------------------------------------------------
+# 1. The app navbar on a long Sources page: stuck at the top at a
+#    mid-page scroll AND at the very bottom
+# ---------------------------------------------------------------------------
+
+
+def test_app_header_stuck_at_top_on_sources(
+    page: Page, app_url: str, seeded_kb: None
+) -> None:
+    page.set_default_timeout(30_000)
+    login(page, app_url)  # → /sources.html (the table is admin-only)
+    expect(page.locator("#docs-tbody tr")).to_have_count(TOTAL_DOCS)
+
+    # The precondition the story needs: the page must actually scroll —
+    # fail loudly if the table ever stops being long enough.
+    sh = page.evaluate("() => document.documentElement.scrollHeight")
+    assert sh > 1.5 * VIEWPORT_H, (
+        f"the Sources table must be long enough to scroll "
+        f"(scrollHeight={sh}, want > {1.5 * VIEWPORT_H:.0f} at a "
+        f"{VIEWPORT_W}×{VIEWPORT_H} viewport) — add more generated docs"
+    )
+
+    # Mid-page scroll (~1 viewport down — the pre-fix un-pin point): the
+    # navbar is still stuck at the top.
+    page.evaluate("() => window.scrollTo(0, 800)")
+    assert (
+        page.evaluate("() => window.scrollY") >= VIEWPORT_H - TOP_TOL_PX
+    ), "the test scroll must land"
+    _assert_top_is_zero(page, ".app-header")
+
+    # And at the very bottom (the audit's −1264px repro): stuck, and
+    # still visible.
+    page.evaluate("() => window.scrollTo(0, 999999)")
+    _assert_top_is_zero(page, ".app-header")
+    expect(page.locator(".app-header")).to_be_visible()
+
+
+# ---------------------------------------------------------------------------
+# 2. The document viewer's two-row header on a long doc: stuck at the top
+#    at the bottom of the scroll
+# ---------------------------------------------------------------------------
+
+
+def test_doc_header_stuck_at_top_on_long_document(
+    page: Page, app_url: str, seeded_kb: None
+) -> None:
+    page.set_default_timeout(30_000)
+    # The dedicated viewer page (phase 10/26 contract) on the generated
+    # long doc — source ``gen``, path ``doc-long.md``.
+    page.goto(f"{app_url}/document.html?source=gen&path=doc-long.md")
+    expect(page.locator("#doc-title")).to_have_text("Sticky long document")
+    expect(page.locator("#doc-content .doc-md")).not_to_be_empty()
+
+    # The doc must actually scroll (the ~40,000-char body fills many
+    # viewports in the 46rem column).
+    sh = page.evaluate("() => document.documentElement.scrollHeight")
+    assert sh > VIEWPORT_H, (
+        f"the long document must make the page scroll "
+        f"(scrollHeight={sh}, want > {VIEWPORT_H})"
+    )
+
+    # To the very bottom: BOTH header rows stay pinned (the header
+    # element is content-sized + sticky — phase 34).
+    page.evaluate("() => window.scrollTo(0, document.documentElement.scrollHeight)")
+    assert (
+        page.evaluate("() => window.scrollY") >= sh - VIEWPORT_H - TOP_TOL_PX
+    ), "the test scroll must land at the document bottom"
+    _assert_top_is_zero(page, ".doc-header")
+
+
+# ---------------------------------------------------------------------------
+# 3. Short-page regression: the phase-52 layout is EXACTLY as it was —
+#    body stretched to the viewport, footer pinned to the viewport
+#    bottom, the pinned composer resting in its in-flow slot above the
+#    footer (the drop of the body's height cap must not have moved a
+#    single pixel of the non-scrolling layout)
+# ---------------------------------------------------------------------------
+
+
+def test_short_page_stretch_and_resting_composer_intact(
+    page: Page, app_url: str
+) -> None:
+    page.set_default_timeout(30_000)
+    page.goto(app_url)
+    expect(page.locator("#empty-state")).to_be_visible()
+
+    # The stretch holds: the body is exactly one viewport tall, and the
+    # grow must not invent scrollable space.
+    sh = page.evaluate("() => document.documentElement.scrollHeight")
+    assert sh <= VIEWPORT_H + TOP_TOL_PX, (
+        f"an empty chat must not be scrollable (scrollHeight={sh})"
+    )
+    body = page.locator("body").bounding_box()
+    assert body is not None
+    assert abs(body["height"] - VIEWPORT_H) <= TOP_TOL_PX, (
+        f"the body must stretch to the viewport (height={body['height']:.2f}, "
+        f"want {VIEWPORT_H}) — the min-height: 100dvh driver is intact"
+    )
+
+    # The footer is pinned to the viewport bottom (the audit's 800/800).
+    footer = page.locator(".app-footer").bounding_box()
+    assert footer is not None
+    footer_bottom = footer["y"] + footer["height"]
+    assert abs(footer_bottom - VIEWPORT_H) <= TOP_TOL_PX, (
+        f"the footer must sit at the viewport bottom "
+        f"(bottom={footer_bottom:.2f}, want {VIEWPORT_H})"
+    )
+
+    # The phase-52 pinned composer holds: the pin itself (position:
+    # sticky) and its RESTING geometry — in-flow, at the bottom of the
+    # screen, with only chrome (the footer + the settled slot's flow
+    # padding) in the band below it, never overlapping the footer.
+    assert (
+        page.evaluate(
+            "() => getComputedStyle(document.querySelector('#composer')).position"
+        )
+        == "sticky"
+    ), "the composer must keep its phase-52 sticky pin"
+    composer = page.locator("#composer").bounding_box()
+    assert composer is not None
+    composer_bottom = composer["y"] + composer["height"]
+    deadband = VIEWPORT_H - composer_bottom
+    assert deadband <= footer["height"] + BOTTOM_SLACK_PX, (
+        f"dead band under the composer: {deadband:.0f}px below it with a "
+        f"{footer['height']:.0f}px footer — the resting slot moved"
+    )
+    assert composer_bottom >= VIEWPORT_H * LOWER_PART, (
+        f"the composer rests at {composer_bottom / VIEWPORT_H:.0%} of the "
+        "viewport — it has to sit at the bottom, not under the empty state"
+    )
+    assert composer_bottom <= footer["y"] + TOP_TOL_PX, (
+        f"the composer overlaps the footer (composer bottom="
+        f"{composer_bottom:.2f}, footer top={footer['y']:.2f})"
+    )