"""Phase 137 E2E (Playwright): PDF-embedded images carry the document
context in their summaries — the user path (TODO L3, end to end).

Run in isolation (DB must be up: ``podman compose up -d db``):

    uv run pytest tests/e2e/test_pdf_image_context.py -v --no-cov

TODO L3: "Images extracted from PDFs still don't have any relevant
context in their summaries … Image summaries should always include the
document context if the images come from a document (this includes
markdown files) so the embedder can more effectively retrieve image
sources."

The suite's single module app runs with ``BOR_IMAGES=true`` + the
``pdf`` import token (the ``test_pdf_support.py`` per-suite-app
pattern — the conftest env with the leak guards):

* **Seed 1** (source ``e2e-pdf-imgctx``): ONE fixture PDF at the
  source root (two text pages + one embedded noise PNG on page 2 — the
  phase-126 PyMuPDF recipe, built in the fixture) arrives through the
  REAL admin upload flow + the RAG page's Sync button. The forward
  path (phase 137 task 02) is the story: the embedded image's
  describe call carries the document-context block (``Extracted from
  e2e-pdf-imgctx/report.pdf (page 2):`` + the page's text), so the
  mock's vision model answers the CONTEXT-AWARE canned reply (the
  mock's ``Extracted from `` trigger — the deterministic witness the
  context REACHED the vision model), and the stored
  ``image_context``/``content``/``summary`` carry it;
* **the chat display line** (task 04): a grounded question carrying
  the mock's ``CONTEXT_LINE_TRIGGER`` marker makes the mock QUOTE THE
  EXACT LINE of the image doc's ``<document>`` block — which now
  LEADS with the one-line ``From <source>/report.pdf (page 2)``
  rendering — so the answer proves the display line was in the
  prompt;
* **Seed 2** (source ``e2e-pdf-imgctx-md`` — a FRESH KB: the phase
  re-imports the same PDF plus a ``notes.md`` referencing the
  embedded image by its synthetic path, the phase-125 reference
  shape): the stored context carries BOTH block kinds with the
  document block FIRST (ASSUMPTION A2 — provenance before purpose),
  and the display line carries both clauses in stored order.

Test-order note: the standalone-parity witness asserts against SEED
1's KB (exactly the PDF + its one image — the suite seeds no
standalone image anywhere), so it runs BEFORE seed 2 truncates and
re-imports; the mock's BARE describe branch is pinned by
``test_pdf_support.py`` running green unedited (the regression run —
not duplicated here).
"""
from __future__ import annotations

import json
import os
import re
import subprocess
import sys
import zipfile
from collections.abc import Iterator
from pathlib import Path
from uuid import UUID

import httpx
import pymupdf as fitz  # PyMuPDF — the fixture-PDF builder (the phase-126 recipe)
import pytest
from playwright.sync_api import Browser, Page, expect
from sqlalchemy import select, text

from app.config import Settings
from app.db import SessionLocal
from app.models import Document
from e2e.auth_helpers import login
from e2e.conftest import ADMIN_PASSWORD, SESSION_SECRET, USE_REAL_LLM, _wait_http
from e2e.mock_llm import IMAGE_DESCRIPTION_ANSWER, IMAGE_DESCRIPTION_CONTEXT_ANSWER
from e2e.sync_helpers import counts_line

REPO = Path(__file__).resolve().parents[2]

# ---------------------------------------------------------------------------
# Fixtures + markers (defined LOCALLY — the suites must stay
# standalone; the shapes mirror test_pdf_support's, the values are
# this suite's own).
# ---------------------------------------------------------------------------

SOURCE = "e2e-pdf-imgctx"  # archive 1's stem (archive_source_name)
SOURCE_MD = "e2e-pdf-imgctx-md"  # archive 2's stem
DOC_PATH = "report.pdf"
IMAGE_REL = "report.pdf#page=2#img=0.png"  # the synthetic embedded-image path
MD_PATH = "notes.md"
PDF_TITLE = "Homelab Report"  # the metadata title

#: The fixture PDF's page texts. ``PAGE_TWO`` (the embedded image's
#: page) carries the document text that must reach the image's
#: ``image_context``; the anchor question's tokens overlap these, so
#: the mock's token-overlap gate grounds on the image doc (and FTS
#: corroborates).
PAGE_ONE = "The quarterly homelab report covers the core switch firmware upgrade."
PAGE_TWO = "The homelab backup schedule runs nightly at 02:00 and keeps seven rotations."

def _embedded_png() -> bytes:
    """A small deterministic colorful noise PNG (channel means ~97 —
    the "real image" stand-in that CLEARS the phase-151 blank/
    decorative gate's near-white floor with room to spare). The old
    1×1 transparent fixture decomposed in PyMuPDF to a near-white
    1-sample base — blank by the owner-locked gate — and is now
    (correctly) skipped as a decorative underlay, so the suite's
    pipeline pins ride on a real non-blank image instead (the
    pipeline is content-agnostic; the well-formed bytes keep the
    extraction + copy path honest)."""
    pix = fitz.Pixmap(fitz.csRGB, fitz.IRect(0, 0, 24, 18))
    for y in range(18):
        for x in range(24):
            pix.set_pixel(x, y, ((x * 7) % 256, (y * 13) % 256, ((x + y) * 5) % 256))
    return pix.tobytes("png")


#: The embedded fixture image (24×18 colorful noise — non-blank by the
#: phase-151 gate; see :func:`_embedded_png`).
EMBED_PNG = _embedded_png()

# Seed 1's stored document block (NO markdown reference exists in that
# source — the doc block alone: the provenance's origin line + the
# page's text).
DOC_BLOCK = f"Extracted from {SOURCE}/{DOC_PATH} (page 2):\n{PAGE_TWO}"

#: The task-04 ONE-LINE rendering of :data:`DOC_BLOCK` — the display
#: line that leads the image doc's ``<document>`` block (test 2).
FROM_LINE = f"From {SOURCE}/{DOC_PATH} (page 2)"
FROM_LINE_MD = f"From {SOURCE_MD}/{DOC_PATH} (page 2)"

#: Archive 2's markdown — the phase-125 reference shape: the embedded
#: image referenced by its SYNTHETIC path (the doc's ``path``), alt
#: "network diagram", one paragraph before + one after (the default
#: two-paragraph window).
NOTES_MD = (
    "# Homelab notes\n"
    "\n"
    "The network diagram in the report shows the server room layout.\n"
    "\n"
    f"![network diagram]({IMAGE_REL})\n"
    "\n"
    "Keep the diagram in sync with the VLAN plan.\n"
)
MD_BLOCK_HEADER = f"Referenced in {SOURCE_MD}/{MD_PATH}:"

#: The grounded question — the mock's ``CONTEXT_LINE_TRIGGER`` marker
#: (the zero-read context-line echo — the mock quotes the image doc's
#: block's exact first line) + the phase-122/125 grounding phrase
#: (the diagram wording is in :data:`IMAGE_DESCRIPTION_CONTEXT_ANSWER`,
#: so the token-overlap cosine clears the mock-calibrated gate 0.30;
#: FTS corroborates).
ANCHOR_QUESTION = (
    "quote the image reference — what is shown in the homelab network diagram?"
)

#: The honest-deflection opening (the gate must NOT fire on the marker
#: question — a deflected prompt carries no ``<documents>`` block, so
#: the mock would never see the image doc).
DEFLECT_OPENING = "I haven't done anything like that"

UPLOAD_TIMEOUT_MS = 30_000
SYNC_TIMEOUT_MS = 60_000
SYNCED_LABEL = re.compile(r"^Synced \d{1,2}:\d{2}$")


# ---------------------------------------------------------------------------
# Module app: images ON — the conftest env pattern with the phase-126
# knobs + leak guards (the conftest session app is never started in
# this isolated run, so no port clash).
# ---------------------------------------------------------------------------


def _app_env(mock_llm: int, app_port: int, scratch: Path) -> dict[str, str]:
    """The conftest app env (leak guards included) with the phase-126
    knobs: ``BOR_IMPORT_EXTENSIONS`` pinned to a set carrying the
    ``pdf`` token (the feature is gated by the token — an operator's
    local gitignored ``.env`` cannot leak the scope in either
    direction), ``BOR_IMAGES`` pinned EXPLICITLY true (the story),
    and the image/upload homes in the suite's scratch dir (the app
    under test must not write copies into the owner's real
    ``~/bor-sources``)."""
    env = dict(os.environ)
    env.pop("DEBUGPY", None)
    env["BOR_ENVIRONMENT"] = "e2e"
    env["BOR_STATIC_DIR"] = str(REPO / "frontend")
    env["BOR_LLM_BASE_URL"] = (
        "https://aipi.reeseapps.com/v1"
        if USE_REAL_LLM
        else f"http://127.0.0.1:{mock_llm}/v1"
    )
    # Mock-calibrated gate (the test_image_anchor_context values) —
    # the anchor question grounds on these (see ANCHOR_QUESTION).
    env["BOR_RELEVANCE_THRESHOLD"] = "0.30"
    env["BOR_LEXICAL_SUPPORT_FLOOR"] = "0.15"
    env["BOR_SOURCE_USEFULNESS_FLOOR"] = "0.15"
    # Phase 67: instant retry waits + the code-default budget.
    env["BOR_LLM_RETRY_DELAY"] = "0"
    env["BOR_LLM_RETRIES"] = str(Settings.model_fields["llm_retries"].default)
    env.setdefault(
        "BOR_DATABASE_URL",
        "postgresql+psycopg://reese:reese@localhost:5432/brain_of_reese",
    )
    env["BOR_ADMIN_PASSWORD"] = ADMIN_PASSWORD
    env["BOR_SESSION_SECRET"] = SESSION_SECRET
    # Leak guards (conftest pattern).
    env["BOR_GIT_SOURCES"] = ""
    env["BOR_DOCS_REPO"] = ""
    env["BOR_SUGGESTIONS"] = json.dumps(
        Settings.model_fields["suggestions"].default
    )
    env["BOR_INPUT_PLACEHOLDER"] = Settings.model_fields["input_placeholder"].default
    env["BOR_FOOTER_TEXT"] = Settings.model_fields["footer_text"].default
    # The import scope WITH the ``pdf`` token + the toggle under test
    # + the suite-private homes.
    env["BOR_IMPORT_EXTENSIONS"] = "md,markdown,txt,pdf"
    env["BOR_IMAGES"] = "true"
    env["BOR_UPLOAD_DIR"] = str(scratch / "uploads")
    env["BOR_SOURCES_DIR"] = str(scratch / "checkouts")
    env["BOR_IMAGE_DIR"] = str(scratch / "images")
    return env


@pytest.fixture(scope="module")
def app_server(mock_llm: int, tmp_path_factory: pytest.TempPathFactory) -> Iterator[str]:
    """The module app — ``BOR_IMAGES=true`` + the ``pdf`` token (the
    module env override)."""
    scratch = tmp_path_factory.mktemp("bor_pdf_imgctx")
    port = int(os.environ.get("E2E_APP_PORT_PDF_IMG_CTX", "8154"))
    proc = subprocess.Popen(
        [sys.executable, "-m", "uvicorn", "app.main:app",
         "--host", "127.0.0.1", "--port", str(port), "--log-level", "warning"],
        cwd=REPO,
        env=_app_env(mock_llm, port, scratch),
    )
    try:
        _wait_http(f"http://127.0.0.1:{port}/api/health")
        yield f"http://127.0.0.1:{port}"
    finally:
        proc.terminate()
        try:
            proc.wait(timeout=10)
        except subprocess.TimeoutExpired:
            proc.kill()


@pytest.fixture(scope="module")
def app_url(app_server: str) -> str:
    return app_server


# ---------------------------------------------------------------------------
# Fixture archives (built in tmp dirs — ``test_sources/`` is never
# touched, the house rule)
# ---------------------------------------------------------------------------


def _build_pdf(root: Path) -> Path:
    """The fixture PDF (the phase-126 recipe, built LOCALLY): two
    text pages + one embedded noise PNG on page 2 + the metadata
    title."""
    pdf_path = root / DOC_PATH
    doc = fitz.open()
    doc.new_page().insert_text((72, 72), PAGE_ONE)
    page2 = doc.new_page()
    page2.insert_text((72, 72), PAGE_TWO)
    page2.insert_image(fitz.Rect(72, 150, 96, 168), stream=EMBED_PNG)
    doc.set_metadata({"title": PDF_TITLE})
    doc.save(pdf_path)
    doc.close()
    return pdf_path


@pytest.fixture(scope="module")
def zip_path(tmp_path_factory: pytest.TempPathFactory) -> Path:
    """Seed 1's archive: ONE PDF at the root — source
    ``e2e-pdf-imgctx``, document path ``report.pdf``."""
    root = tmp_path_factory.mktemp("bor_pdfimgctx_zip")
    pdf_path = _build_pdf(root)
    archive = root / f"{SOURCE}.zip"
    with zipfile.ZipFile(archive, "w", zipfile.ZIP_DEFLATED) as zf:
        zf.write(pdf_path, arcname=DOC_PATH)
    return archive


@pytest.fixture(scope="module")
def zip_md_path(tmp_path_factory: pytest.TempPathFactory) -> Path:
    """Seed 2's archive: the SAME PDF + ``notes.md`` at the root
    (the markdown references the embedded image by its synthetic
    path, with a paragraph of context before and after) — source
    ``e2e-pdf-imgctx-md``."""
    root = tmp_path_factory.mktemp("bor_pdfimgctx_md_zip")
    pdf_path = _build_pdf(root)
    (root / MD_PATH).write_text(NOTES_MD, encoding="utf-8")
    archive = root / f"{SOURCE_MD}.zip"
    with zipfile.ZipFile(archive, "w", zipfile.ZIP_DEFLATED) as zf:
        zf.write(pdf_path, arcname=DOC_PATH)
        zf.write(root / MD_PATH, arcname=MD_PATH)
    return archive


# ---------------------------------------------------------------------------
# DB + UI helpers (the test_pdf_support pattern)
# ---------------------------------------------------------------------------


def _truncate_all() -> None:
    """Fresh KB + registry per seed (the E2E isolation pattern): the
    suites share one Postgres, and a leftover row would corrupt the
    counts. ``sources_meta`` (the KB generation counter) resets with
    the KB — the sync re-creates the row."""
    with SessionLocal() as db:
        db.execute(text(
            "TRUNCATE chunks, documents, query_log, kb_overview, "
            "git_sources, sources_meta, folder_summaries"
        ))
        db.commit()


def _health_db(app_url: str) -> bool:
    try:
        return httpx.get(f"{app_url}/api/health", timeout=5).json()["db"] == "up"
    except Exception:  # noqa: BLE001 — unreachable is the skip case
        return False


def _ready_for_sync_line(source: str) -> re.Pattern[str]:
    """Phase 154 (task 02): the ready-for-sync line carrying the
    completion stamp — "Uploaded <source> (<stamp>) — press Sync
    sources to import it." (the fresh 202 settle). In E2E the stamp
    is ALWAYS the same-day ``HH:MM`` form (the run settles within
    seconds; the date-qualified forms are unit-pinned on a fixed
    clock — E2E never depends on the wall clock)."""
    return re.compile(
        rf"^Uploaded {re.escape(source)} \(\d{{1,2}}:\d{{2}}\)"
        r" — press Sync sources to import it\.$"
    )


def _upload_zip(page: Page, app_url: str, archive: Path, source: str) -> None:
    """The real admin upload flow: form login → the git-sources page →
    pick the archive → submit → the terminal result line (phase 90 A3,
    phase 154 task 02: "Uploaded <source> (<stamp>) — press Sync
    sources to import it." — the completion stamp)."""
    login(page, app_url, next="/git-sources.html")
    expect(page).to_have_url(app_url + "/git-sources.html", timeout=30_000)
    expect(page.locator("#sign-out-btn")).to_be_visible(timeout=15_000)
    page.set_input_files("#archive-upload-file", str(archive))
    page.click("#archive-upload-btn")
    result = page.locator("#archive-upload-result")
    expect(result).to_be_visible(timeout=UPLOAD_TIMEOUT_MS)
    expect(result).to_have_text(
        _ready_for_sync_line(source),
        timeout=UPLOAD_TIMEOUT_MS,
    )


def _sync_via_ui(page: Page, app_url: str, expected_result: str) -> None:
    """The RAG page's "Sync sources" button (the scan): click →
    "Syncing…" → the terminal "Synced HH:MM" label + the fresh counts
    in #sync-progress (the never-stale contract)."""
    page.goto(app_url + "/sources.html")
    btn = page.locator("#sync-btn")
    expect(btn).to_be_visible(timeout=30_000)
    expect(page.locator("#sync-label")).to_have_text(
        re.compile(r"^Sync sources$|^Synced \d{1,2}:\d{2}$")
    )
    btn.click()
    expect(btn).to_be_disabled()
    expect(page.locator("#sync-label")).to_have_text("Syncing…")
    expect(page.locator("#sync-label")).to_have_text(SYNCED_LABEL, timeout=SYNC_TIMEOUT_MS)
    expect(btn).to_be_enabled()
    expect(page.locator("#sync-progress-text")).to_have_text(counts_line(expected_result))


def _ask(page: Page, app_url: str, question: str) -> None:
    """The chat user path: login → the question → Send → the final
    brain bubble (the Send button re-enabled = the turn is over)."""
    login(page, app_url, next="/")
    expect(page.locator("#kb-banner")).to_be_hidden()
    page.fill("#message-input", question)
    page.click("#send-btn")
    bubble = page.locator(".msg.brain .bubble").last
    expect(page.locator("#send-btn")).to_be_enabled(timeout=60_000)
    expect(page.locator("#send-label")).to_have_text("Send")
    expect(bubble).to_contain_text("Deterministic mock answer", timeout=30_000)


# ---------------------------------------------------------------------------
# The module seeds: upload + sync the fixture archives through the
# real UI, once each (the story E2E truncate/re-import-per-module
# pattern).
# ---------------------------------------------------------------------------


@pytest.fixture(scope="module")
def seeded(
    app_url: str,
    browser: Browser,
    zip_path: Path,
) -> Iterator[dict[str, UUID]]:
    """Seed 1: upload the single-PDF zip through the admin UI, then
    scan it with the RAG page's Sync button (the mock's vision model
    describes the embedded image in-process, WITH the document
    context). The module app's ``/api/config`` flag is asserted first
    — the env override must have reached the app under test, or the
    whole premise of the suite is void."""
    if not _health_db(app_url):
        pytest.skip("Postgres not reachable — run `podman compose up -d db` first")
    cfg = httpx.get(f"{app_url}/api/config", timeout=5).json()
    assert cfg["images"] is True, "the module app must run with BOR_IMAGES=true"

    _truncate_all()
    page = browser.new_page(viewport={"width": 1280, "height": 800})
    try:
        _upload_zip(page, app_url, zip_path, SOURCE)
        # The PDF + its one embedded image (phase 126 A3): both added.
        _sync_via_ui(page, app_url, expected_result="2 added")
        with SessionLocal() as db:
            img = db.scalar(
                select(Document).where(
                    Document.source == SOURCE, Document.path == IMAGE_REL
                )
            )
            assert img is not None, "the embedded image must become an image doc"
    finally:
        page.close()
    yield {"image_id": img.id}


@pytest.fixture(scope="module")
def seeded_md(
    app_url: str,
    browser: Browser,
    zip_md_path: Path,
) -> Iterator[dict[str, UUID]]:
    """Seed 2: a FRESH KB (seed 1's rows are truncated — the phase
    re-imports through the SAME UI) seeded with archive 2: the same
    PDF plus the markdown that references its embedded image by the
    synthetic path (the combined-context case)."""
    _truncate_all()
    page = browser.new_page(viewport={"width": 1280, "height": 800})
    try:
        _upload_zip(page, app_url, zip_md_path, SOURCE_MD)
        # The PDF + its one embedded image + the markdown doc: three added.
        _sync_via_ui(page, app_url, expected_result="3 added")
        with SessionLocal() as db:
            img = db.scalar(
                select(Document).where(
                    Document.source == SOURCE_MD, Document.path == IMAGE_REL
                )
            )
            assert img is not None, "the embedded image must become an image doc"
    finally:
        page.close()
    yield {"image_id": img.id}
    _truncate_all()


# ---------------------------------------------------------------------------
# 1. The forward path (the TODO's core complaint): the embedded image's
#    stored context + summary carry the document context
# ---------------------------------------------------------------------------


def test_embedded_image_doc_stores_the_document_context(
    app_url: str, seeded: dict[str, UUID]
) -> None:
    """The owner's complaint, gone, on the ROW: the embedded image's
    ``image_context`` leads with the provenance's origin line (the
    document it came from — source + PDF path + page) and carries the
    page's own text; its ``content`` is ``<context>\\n\\n<description>``
    where the description is the mock's CONTEXT-AWARE canned reply
    (the ``Extracted from `` trigger — the deterministic witness the
    describe call carried the context; the bare pre-137 reply must
    NOT appear), and ``summary`` === ``content`` (the image
    convention)."""
    with SessionLocal() as db:
        img = db.scalar(
            select(Document).where(
                Document.source == SOURCE, Document.path == IMAGE_REL
            )
        )
        assert img is not None, "the embedded image must be a document"
        assert img.is_image is True and img.image_path is not None
        assert img.image_context is not None
        # The origin line is ALWAYS present (even for a text-less page)
        # — here with the page's text on the following line(s).
        assert img.image_context.startswith(
            f"Extracted from {SOURCE}/{DOC_PATH} (page 2):\n"
        )
        assert PAGE_TWO in img.image_context
        # No markdown references this image in seed 1 — the doc block
        # alone (the exact value).
        assert img.image_context == DOC_BLOCK
        # The context-aware reply is the witness the context reached
        # the vision model (the diagram wording is kept, so retrieval
        # still grounds — but it NAMES the document + page).
        assert img.content == f"{DOC_BLOCK}\n\n{IMAGE_DESCRIPTION_CONTEXT_ANSWER}"
        assert img.summary == img.content
        assert IMAGE_DESCRIPTION_ANSWER not in img.content


# ---------------------------------------------------------------------------
# 2. Chat: the suggestion block for the image leads with the one-line
#    From … (page N) display line
# ---------------------------------------------------------------------------


def test_chat_suggestion_leads_with_the_from_line(
    page: Page, app_url: str, seeded: dict[str, UUID]
) -> None:
    """The mock's ``CONTEXT_LINE_TRIGGER`` (the phase-125 marker — no
    new display mock branch): the ZERO-READ echo QUOTES THE EXACT
    LINE of the image doc's ``<document>`` block — which now LEADS
    with the one-line ``From <source>/report.pdf (page 2)`` rendering
    (phase 137 task 04) BEFORE the description. The quoted line in
    the answer proves the display line was in the prompt; the
    standalone witness ("stands alone") is absent — the block is NOT
    the bare description."""
    _ask(page, app_url, ANCHOR_QUESTION)
    bubble = page.locator(".msg.brain .bubble").last
    expect(bubble).to_contain_text(FROM_LINE, timeout=30_000)
    expect(bubble).not_to_contain_text("stands alone")
    # Grounded (not deflected) — a deflected prompt would carry no
    # <documents> block at all (the mock would never see the image
    # doc, and would answer with the deflection opening).
    expect(bubble).not_to_contain_text(DEFLECT_OPENING)


# ---------------------------------------------------------------------------
# 4. Standalone parity witness (against seed 1's KB — it must run
#    BEFORE seed 2 truncates and re-imports)
# ---------------------------------------------------------------------------


def test_kb_is_exactly_the_pdf_and_its_image(
    app_url: str, seeded: dict[str, UUID]
) -> None:
    """Seed 1's KB is EXACTLY the PDF + its one embedded image — the
    suite seeds no standalone image anywhere, so the context-aware
    reply fired for the EMBEDDED image's describe call alone (no
    standalone image in this KB to witness the bare branch here). The
    bare branch's byte-identity is pinned by ``test_pdf_support.py``
    running green unedited (the regression run) — not duplicated."""
    with SessionLocal() as db:
        docs = db.scalars(select(Document)).all()
        assert len(docs) == 2, "seed 1's KB is exactly the PDF + its image"
        image_docs = [d for d in docs if d.is_image]
        assert len(image_docs) == 1
        assert image_docs[0].source == SOURCE
        assert image_docs[0].path == IMAGE_REL


# ---------------------------------------------------------------------------
# 3. Seed 2: a markdown reference COMBINES with the document context —
#    the document block first (ASSUMPTION A2), both clauses on the
#    display line
# ---------------------------------------------------------------------------


def test_markdown_reference_combines_the_document_context_first(
    page: Page, app_url: str, seeded_md: dict[str, UUID]
) -> None:
    """The same-source markdown references the embedded image by its
    synthetic path (the phase-125 reference shape) → the stored
    context carries BOTH block kinds: the document block (the
    provenance's origin line + the page text) FIRST, then the
    ``Referenced in e2e-pdf-imgctx-md/notes.md:`` block (provenance
    before purpose — ASSUMPTION A2), and the display line carries
    both clauses in stored order (the mock quotes the block's exact
    first line — the task-04 combined rendering)."""
    with SessionLocal() as db:
        img = db.scalar(
            select(Document).where(
                Document.source == SOURCE_MD, Document.path == IMAGE_REL
            )
        )
        assert img is not None, "the embedded image must be a document"
        assert img.is_image is True
        ctx = img.image_context
        assert ctx is not None
        # STARTS-WITH the document block (origin line + the page text),
        # the Referenced-in block present, and the document block's
        # index BEFORE the markdown block's (document first — A2).
        assert ctx.startswith(
            f"Extracted from {SOURCE_MD}/{DOC_PATH} (page 2):\n{PAGE_TWO}"
        )
        assert MD_BLOCK_HEADER in ctx
        assert ctx.index("Extracted from ") < ctx.index(MD_BLOCK_HEADER)
        # The same describe-call witness as seed 1 (the combined
        # context carries the provenance header): the context-aware
        # reply, content = context + description, summary === content.
        assert img.content == f"{ctx}\n\n{IMAGE_DESCRIPTION_CONTEXT_ANSWER}"
        assert img.summary == img.content

    # The display line: the task-04 combined rendering — the document
    # clause first, the reference clause after.
    _ask(page, app_url, ANCHOR_QUESTION)
    bubble = page.locator(".msg.brain .bubble").last
    expect(bubble).to_contain_text(FROM_LINE_MD, timeout=30_000)
    expect(bubble).to_contain_text(MD_BLOCK_HEADER)
    expect(bubble).not_to_contain_text(DEFLECT_OPENING)