Merge pull request 'SLICE-8: Shopify dialect — detect/map Shopify export at the codec boundary + DOC-2/3 (SD-0002 §7.2)' (#32) from slice-8-shopify-dialect into main

2026-06-12 09:37:37 +00:00
parent 8ed9b25771 a851d3587c
commit e2d8b5caae
21 changed files with 1242 additions and 18 deletions
@@ -1 +1 @@
-0.7.0
+0.8.0
@@ -35,11 +35,13 @@ from .service import (
 # DOC-3: the downloadable worked-example CSV the BFF serves at /api/products/sample.csv.
 SAMPLE_CSV_PATH = Path(__file__).parent / "sample.csv"
 # DOC-2: the column reference the BFF serves at /api/products/columns.md.
 COLUMNS_MD_PATH = Path(__file__).parent / "columns.md"
 __all__ = [
    "ProductsError", "FileRejected", "DraftNotFound", "DraftExpired",
    "PreviewStale", "NothingToApply", "RunNotFound", "EmptyCatalog",
-    "MAX_DATA_ROWS", "MAX_FILE_BYTES", "SAMPLE_CSV_PATH",
+    "MAX_DATA_ROWS", "MAX_FILE_BYTES", "SAMPLE_CSV_PATH", "COLUMNS_MD_PATH",
    "import_validate", "get_draft", "get_draft_records", "discard_draft",
    "confirm_draft", "list_runs", "get_run", "summary", "export_catalog",
    "run_image_phase", "recover_incomplete_runs", "image_for_serving",
@@ -6,6 +6,7 @@ from __future__ import annotations
 import csv
 import io
 from .dialect_shopify import is_shopify_header, map_shopify_header
 from .errors import FileRejected
 from .models import KNOWN_COLUMNS, MAX_DATA_ROWS, MAX_FILE_BYTES, ParsedFile, Row
@@ -13,8 +14,8 @@ _REQUIRED_HEADER_COLUMNS = ("Handle", "Title")
 def detect_dialect(header: list[str]) -> str:
-    """The INV-17 seam: SLICE-8 recognizes Shopify's exact header set here."""
+    """The INV-17 seam: recognize Shopify's header set, else canonical (§6.5.1)."""
-    return "canonical"
+    return "shopify" if is_shopify_header(header) else "canonical"
 def parse_csv(data: bytes) -> ParsedFile:
@@ -31,19 +32,34 @@ def parse_csv(data: bytes) -> ParsedFile:
        except StopIteration:
            raise FileRejected("not_csv", "This file isn't readable as CSV.") from None
        header = [h.strip() for h in raw_header]
        dialect = detect_dialect(header)
        # INV-17: normalize the header to canonical names at the boundary. mapped[i]
        # is the canonical name for header[i] (or None when that column has no
        # canonical home); unknown is the not-imported warning list. Canonical files
        # map to themselves; unknown columns are warned exactly as before.
        if dialect == "shopify":
            mapped, unknown = map_shopify_header(header)
        else:
            mapped = [c if c in KNOWN_COLUMNS else None for c in header]
            unknown = [c for c in header if c and c not in KNOWN_COLUMNS]
        for col in _REQUIRED_HEADER_COLUMNS:
-            if col not in header:
+            if col not in mapped:
                raise FileRejected(
                    "missing_required_column",
                    f"This file is missing the required column '{col}'.",
                )
-        # First occurrence of a duplicated column wins.
+
        # First occurrence of a duplicated canonical column wins.
        col_index: dict[str, int] = {}
-        for i, name in enumerate(header):
+        for i, name in enumerate(mapped):
            if name and name not in col_index:
                col_index[name] = i
-        known_present = [c for c in col_index if c in KNOWN_COLUMNS]
+        # De-dup the warning list, order-preserving.
-        unknown = [c for c in col_index if c not in KNOWN_COLUMNS]
+        seen: set[str] = set()
        unknown = [c for c in unknown if not (c in seen or seen.add(c))]
        rows: list[Row] = []
        for raw in reader:
            if not any(cell.strip() for cell in raw):
@@ -55,11 +71,16 @@ def parse_csv(data: bytes) -> ParsedFile:
                )
            cells = {
                c: (raw[col_index[c]].strip() if col_index[c] < len(raw) else "")
-                for c in known_present
+                for c in col_index
            }
            # Shopify grams carry an implicit unit; canonical needs it explicit. In a
            # Shopify file "Variant Weight" can only come from the Variant Grams rename
            # (a canonical-named Variant Weight would have vetoed Shopify detection), so
            # weight and unit move together: a value -> "g"; a cleared grams (present-but-
            # empty) clears the unit too, never leaving a stale unit (§6.5.1).
            if dialect == "shopify" and "Variant Weight" in cells:
                cells["Variant Weight Unit"] = "g" if cells["Variant Weight"] else ""
            rows.append(Row(line_number=reader.line_num, cells=cells))
    except csv.Error:
        raise FileRejected("not_csv", "This file isn't readable as CSV.") from None
-    return ParsedFile(
+    return ParsedFile(dialect=dialect, header=header, unknown_columns=unknown, rows=rows)
        dialect=detect_dialect(header), header=header, unknown_columns=unknown, rows=rows
    )
@@ -0,0 +1,95 @@
 # Product CSV — column reference
 This is the complete reference for the product CSV you import into and export from
 your store (SD-0002 §6.5.1). The format is **canonical** — a clean superset of the
 Shopify product CSV — and a **Shopify product CSV** imports directly too: we detect
 which one you uploaded and map it for you (see *Shopify dialect* below).
 You don't pick a format. Upload your file; the preview tells you which format was
 recognized and shows exactly what will change before anything is applied.
 ## File shape
 - UTF-8 (a byte-order mark is tolerated), comma-delimited, RFC 4180 quoting.
 - A header row is **required**. `Handle` and `Title` are the only always-required
  columns.
 - Up to 5,000 rows and 10 MB per file. Split larger catalogs and import in parts.
 ## Row grammar
 Consecutive rows that share a `Handle` describe **one product**. The product's first
 row carries the product-level fields (`Title` is required there). Each row may carry:
 - a **variant** — its `Option n Value`s plus `Variant *` fields;
 - an **image** — `Image Src` with `Image Position` / `Image Alt Text`;
 - or both.
 An image-only row (just `Handle` + `Image *`) is valid — that's how a product carries
 more images than it has variants.
 ## Updating: blank vs. absent
 - A column **absent from your file** is left untouched on existing products.
 - A cell that is **present but empty** clears that field (resets it to its default).
 Every clear is shown explicitly in the preview, so this is deliberate, visible
 behavior — never a silent surprise.
 ## Canonical columns
 | Column | Level | Required | Notes |
 | --- | --- | --- | --- |
 | `Handle` | product | every row | Identity: lowercase letters, numbers, and dashes. |
 | `Title` | product | first row of a product | |
 | `Description` | product | — | HTML allowed; sanitized on import. |
 | `Vendor` | product | — | Free text. |
 | `Type` | product | — | `standalone` (default). `kit_virtual` / `kit_assembled` are reserved; any non-`standalone` value is a row error until kits ship. |
 | `Google Product Category` | product | — | Taxonomy string. |
 | `Tags` | product | — | Comma-separated within the cell. |
 | `Status` | product | — | `draft` \| `active` \| `archived`; defaults to `active` on add. |
 | `Published` | product | — | `TRUE` \| `FALSE`; defaults to `TRUE` on add. |
 | `Option1 Name` … `Option3 Name` | product | with values | e.g. "Size". A value without its name is a row error. |
 | `Option1 Value` … `Option3 Value` | variant | per variant | The variant's identity combination. |
 | `Variant SKU` | variant | — | Indexed; not identity. |
 | `Variant Barcode` | variant | — | |
 | `Variant Price` | variant | — | Decimal; no currency symbol. |
 | `Variant Cost` | variant | — | Decimal. |
 | `Variant Weight` + `Variant Weight Unit` | variant | — | Decimal weight plus a unit string. |
 | `Variant Volume` + `Variant Volume Unit` | variant | — | Decimal volume plus a unit string. |
 | `Variant Tax ID 1` / `Variant Tax ID 2` | variant | — | Opaque references. |
 | `Variant Inventory Tracker` | variant | — | |
 | `Variant Inventory Qty` | variant | — | Integer ≥ 0. |
 | `Variant Position` | variant | — | Display order; defaults to file order. |
 | `Image Src` | image | — | URL (or a store-hosted URL on re-import). |
 | `Image Position` | image | — | Integer order. |
 | `Image Alt Text` | image | — | |
 | `Variant Image` | variant | — | URL for this variant's specific image. |
 | `Component 1 SKU` / `Component 1 Quantity` … `Component 10 …` | variant | — | Reserved for kits — a non-empty value is a row error today. |
 ## Shopify dialect
 If you upload a **Shopify product CSV**, we recognize it by its header set and map it
 to the canonical columns automatically. The preview labels it *"Shopify product
 CSV — mapped"*.
 **Mapped — renamed**
 | Shopify column | Becomes |
 | --- | --- |
 | `Body (HTML)` | `Description` |
 | `Product Category` | `Google Product Category` |
 | `Cost per item` | `Variant Cost` |
 | `Variant Grams` | `Variant Weight` (in grams) |
 **Mapped — same name:** `Handle`, `Title`, `Vendor`, `Tags`, `Published`, `Status`,
 `Option1–3 Name` / `Option1–3 Value`, `Variant SKU`, `Variant Barcode`,
 `Variant Price`, `Variant Inventory Tracker`, `Variant Inventory Qty`,
 `Variant Image`, `Image Src`, `Image Position`, `Image Alt Text`.
 **Not imported — listed in the preview as a heads-up, never silently dropped:** the
 Shopify free-text `Type` (canonical `Type` is structural, so we don't fold a category
 string into it), `Variant Compare At Price`, `Variant Inventory Policy`,
 `Variant Fulfillment Service`, `Variant Requires Shipping`, `Variant Taxable`,
 `Variant Tax Code`, `Gift Card`, SEO fields, every `Google Shopping / …` field, and
 market/region price columns. These have no canonical home yet; your other data still
 imports.
@@ -0,0 +1,95 @@
 """Shopify product-CSV adapter (INV-17): detect by header signature, map to canonical.
 The mapping is the §6.5.1 contract; the exhaustive table is pinned here and
 mirrored by tests/test_products_dialect_shopify.py + e2e/fixtures/shopify-export.csv.
 """
 from __future__ import annotations
 from .models import KNOWN_COLUMNS
 # Shopify header -> canonical header (renames only; direct same-name columns pass
 # through via KNOWN_COLUMNS). Variant Grams carries a value transform (see codec).
 SHOPIFY_RENAME: dict[str, str] = {
    "Body (HTML)": "Description",
    "Product Category": "Google Product Category",
    "Cost per item": "Variant Cost",
    "Variant Grams": "Variant Weight",
 }
 # Canonical-named columns Shopify uses differently — must NOT pass through.
 # Type: Shopify's free-text type vs canonical's structural Type (§6.5.1, decision D).
 # Variant Weight Unit: superseded by the Variant Grams -> Variant Weight transform.
 SHOPIFY_DROP: frozenset[str] = frozenset({"Type", "Variant Weight Unit"})
 # Columns whose presence proves the file is a Shopify export (canonical never has them).
 _SIGNATURE: frozenset[str] = frozenset(
    {
        "Body (HTML)",
        "Variant Grams",
        "Cost per item",
        "Variant Compare At Price",
        "Variant Inventory Policy",
        "Variant Fulfillment Service",
        "Variant Requires Shipping",
        "Variant Taxable",
        "Gift Card",
        "SEO Title",
        "SEO Description",
    }
 )
 # Canonical-distinctive columns — names Shopify renames away (so a real Shopify export
 # never carries them) plus canonical-only columns Shopify has no equivalent for. Their
 # presence proves the file is canonical and VETOES Shopify detection: detection must
 # lean conservative, because under-detection is safe (Shopify-named columns are warned
 # as not-imported) while over-detection corrupts (canonical Type / weight-unit are
 # dropped). This closes the misdetection hazard — a canonical file that merely contains
 # a stray signature-named column (e.g. `SEO Title`) is never misread as Shopify (§7.4).
 _CANONICAL_SIGNATURE: frozenset[str] = frozenset(
    {
        "Description",
        "Variant Cost",
        "Variant Weight",
        "Google Product Category",
        "Variant Volume",
        "Variant Volume Unit",
        "Variant Tax ID 1",
        "Variant Tax ID 2",
        "Variant Position",
    }
 )
 def is_shopify_header(header: list[str]) -> bool:
    """True iff the header carries a Shopify-only signature column AND no
    canonical-distinctive column. A canonical signal vetoes Shopify detection so an
    ambiguous or hybrid header is treated as canonical — where Shopify-named columns
    are warned as not-imported rather than silently remapped (never misparses, §7.4)."""
    cols = {h.strip() for h in header}
    if cols & _CANONICAL_SIGNATURE:
        return False
    if cols & _SIGNATURE:
        return True
    return any(c.startswith("Google Shopping / ") for c in cols)
 def map_shopify_header(header: list[str]) -> tuple[list[str | None], list[str]]:
    """Return (mapped, not_imported): mapped[i] is the canonical name for header[i],
    or None when that Shopify column has no canonical home; not_imported lists the
    original Shopify names (in order) that were dropped — the preview warning."""
    mapped: list[str | None] = []
    not_imported: list[str] = []
    for raw in header:
        col = raw.strip()
        if col in SHOPIFY_RENAME:
            mapped.append(SHOPIFY_RENAME[col])
        elif col in SHOPIFY_DROP:
            mapped.append(None)
            not_imported.append(col)
        elif col in KNOWN_COLUMNS:
            mapped.append(col)
        else:
            mapped.append(None)
            if col:
                not_imported.append(col)
    return mapped, not_imported
@@ -450,6 +450,14 @@ def create_app(database_url: str | None = None, static_dir: str | Path | None =
            headers={"content-disposition": 'attachment; filename="ecomm-products-sample.csv"'},
        )
    @app.get("/api/products/columns.md")
    def products_columns_md():
        """The DOC-2 column reference. Documentation, so no auth gate (§6.4)."""
        return PlainTextResponse(
            products.COLUMNS_MD_PATH.read_text(),
            media_type="text/markdown; charset=utf-8",
        )
    # Deployed topology (launch-app SPEC §2): nginx proxies everything here, so the
    # backend serves the built SPA. Mounted LAST so /healthz and /api/* win. In dev the
    # dist dir doesn't exist (Vite serves the frontend) and the mount is skipped.
@@ -0,0 +1,4 @@
 Handle,Title,Body (HTML),Vendor,Product Category,Type,Tags,Published,Status,Option1 Name,Option1 Value,Variant SKU,Variant Grams,Variant Inventory Tracker,Variant Inventory Qty,Variant Inventory Policy,Variant Fulfillment Service,Variant Price,Variant Compare At Price,Variant Requires Shipping,Variant Taxable,Variant Barcode,Image Src,Image Position,Image Alt Text,Gift Card,SEO Title,SEO Description,Google Shopping / MPN,Variant Image,Variant Weight Unit,Cost per item,Status
 star-tee,Star Tee,<p>Soft cotton tee.</p>,Wiggle Goods,Apparel & Accessories > Clothing,Shirts,"apparel, tees",TRUE,active,Size,S,WG-TEE-S,180,shopify,12,deny,manual,24.00,30.00,TRUE,TRUE,0001,https://img.example.com/star-tee.jpg,1,Star Tee,FALSE,Star Tee | Wiggle,Soft tee,MPN-1,https://img.example.com/star-s.jpg,g,11.00,active
 star-tee,,,,,,,,,,M,WG-TEE-M,180,shopify,18,deny,manual,24.00,30.00,TRUE,TRUE,0002,,,,FALSE,,,,,g,11.00,
 star-tee,,,,,,,,,,,,,,,,,,,,,,https://img.example.com/star-back.jpg,2,Star Tee back,,,,,,,,
@@ -67,3 +67,29 @@ def test_missing_column_message_names_the_column():
    with pytest.raises(FileRejected) as exc:
        parse_csv(_csv("Handle,Vendor", "mug,Acme"))
    assert "'Title'" in exc.value.message
 def test_parse_detects_and_maps_shopify():
    data = (
        "Handle,Title,Body (HTML),Cost per item,Variant Price,Variant Grams,Type,Gift Card\n"
        "mug,Moon Mug,<p>Grey</p>,9.50,18.00,300,Drinkware,false\n"
    ).encode("utf-8")
    parsed = parse_csv(data)
    assert parsed.dialect == "shopify"
    cells = parsed.rows[0].cells
    assert cells["Description"] == "<p>Grey</p>"
    assert cells["Variant Cost"] == "9.50"
    assert cells["Variant Weight"] == "300"
    assert cells["Variant Weight Unit"] == "g"  # synthesized
    # Type (free-text) and Gift Card warned, never mapped:
    assert "Type" in parsed.unknown_columns
    assert "Gift Card" in parsed.unknown_columns
    assert "product_type" not in str(cells)  # Type never reached canonical
 def test_parse_canonical_unchanged():
    data = b"Handle,Title,Description,Variant Price\nmug,Moon Mug,Grey,18.00\n"
    parsed = parse_csv(data)
    assert parsed.dialect == "canonical"
    assert parsed.rows[0].cells["Description"] == "Grey"
    assert parsed.unknown_columns == []
@@ -0,0 +1,121 @@
 """Shopify dialect adapter — detection + the §6.5.1 mapping contract (SLICE-8)."""
 from pathlib import Path
 from app.domains.products.codec import parse_csv
 from app.domains.products.dialect_shopify import is_shopify_header, map_shopify_header
 _FIXTURE = Path(__file__).parent / "fixtures" / "shopify-export.csv"
 def test_detects_shopify_by_signature_column():
    assert is_shopify_header(["Handle", "Title", "Body (HTML)", "Variant Price"]) is True
    assert is_shopify_header(["Handle", "Title", "Google Shopping / MPN"]) is True
 def test_canonical_header_is_not_shopify():
    assert is_shopify_header(["Handle", "Title", "Description", "Variant Cost"]) is False
 def test_ambiguous_shared_only_header_defaults_canonical():
    # Only columns common to both dialects -> not Shopify (safe default, never misparse).
    assert (
        is_shopify_header(["Handle", "Title", "Option1 Name", "Variant Price", "Image Src"])
        is False
    )
 def test_map_renames_and_passes_through():
    mapped, not_imported = map_shopify_header(
        ["Handle", "Body (HTML)", "Cost per item", "Variant Price"]
    )
    assert mapped == ["Handle", "Description", "Variant Cost", "Variant Price"]
    assert not_imported == []
 def test_map_drops_type_and_weight_unit_overrides():
    mapped, not_imported = map_shopify_header(
        ["Handle", "Type", "Variant Grams", "Variant Weight Unit"]
    )
    assert mapped == ["Handle", None, "Variant Weight", None]
    assert not_imported == ["Type", "Variant Weight Unit"]
 def test_map_drops_shopify_only_and_market_columns():
    mapped, not_imported = map_shopify_header(
        ["Handle", "Variant Compare At Price", "Gift Card", "Price / International"]
    )
    assert mapped == ["Handle", None, None, None]
    assert not_imported == ["Variant Compare At Price", "Gift Card", "Price / International"]
 def test_shopify_fixture_maps_exhaustively():
    parsed = parse_csv(_FIXTURE.read_bytes())
    assert parsed.dialect == "shopify"
    first = parsed.rows[0].cells
    # renamed
    assert first["Description"] == "<p>Soft cotton tee.</p>"
    assert first["Google Product Category"] == "Apparel & Accessories > Clothing"
    assert first["Variant Cost"] == "11.00"
    assert first["Variant Weight"] == "180"
    assert first["Variant Weight Unit"] == "g"
    # direct
    assert first["Variant SKU"] == "WG-TEE-S"
    assert first["Image Src"] == "https://img.example.com/star-tee.jpg"
    # not imported — warned, none leaked into canonical cells
    for col in (
        "Type",
        "Variant Compare At Price",
        "Gift Card",
        "SEO Title",
        "Google Shopping / MPN",
        "Variant Weight Unit",
        "Variant Inventory Policy",
        "Variant Fulfillment Service",
        "Variant Requires Shipping",
        "Variant Taxable",
    ):
        assert col in parsed.unknown_columns, col
    assert "Variant Compare At Price" not in first
 # --- Detection robustness (review findings #1, #2): bias conservative ----------------
 def test_canonical_distinctive_column_vetoes_shopify_detection():
    # A canonical file carrying a stray Shopify-signature name (`SEO Title`) stays
    # canonical because it also has canonical-distinctive columns — no misparse,
    # no dropped Type, no corrupted weight unit (review finding #2).
    header = ["Handle", "Title", "Type", "Variant Weight", "Variant Weight Unit", "SEO Title"]
    assert is_shopify_header(header) is False
 def test_dual_named_file_stays_canonical_and_warns_shopify_name():
    # A malformed file with BOTH `Body (HTML)` and canonical `Description`: the
    # canonical column vetoes detection, so `Body (HTML)` is honestly warned as an
    # unknown column rather than silently shadowing `Description` (review finding #1).
    data = (
        b"Handle,Title,Body (HTML),Description,Variant Price\n"
        b"mug,Moon Mug,FROM_BODY,FROM_DESC,18.00\n"
    )
    parsed = parse_csv(data)
    assert parsed.dialect == "canonical"
    assert parsed.rows[0].cells["Description"] == "FROM_DESC"
    assert "Body (HTML)" in parsed.unknown_columns
 def test_real_shopify_export_still_detected():
    # The conservative veto must not break a genuine Shopify export (no canonical-
    # distinctive columns present).
    parsed = parse_csv(_FIXTURE.read_bytes())
    assert parsed.dialect == "shopify"
 def test_shopify_grams_clear_clears_weight_unit_together():
    # An empty Variant Grams (a clear) clears the synthesized unit too — weight and
    # unit move together, never a stale unit (review finding #3).
    data = b"Handle,Title,Body (HTML),Variant Grams\nmug,Moon Mug,<p>x</p>,\n"
    parsed = parse_csv(data)
    assert parsed.dialect == "shopify"
    cells = parsed.rows[0].cells
    assert cells["Variant Weight"] == ""
    assert cells["Variant Weight Unit"] == ""
@@ -95,6 +95,17 @@ def test_sample_csv_imports_clean(fresh_db_url):
        assert body["summary"]["errors"] == 0 and body["summary"]["adds"] == 2
 def test_columns_md_served(fresh_db_url):
    """DOC-2 column reference is app-served, unauthenticated documentation (§6.4)."""
    with TestClient(create_app(database_url=fresh_db_url)) as client:
        resp = client.get("/api/products/columns.md")
        assert resp.status_code == 200
        assert "text/markdown" in resp.headers["content-type"]
        body = resp.text
        assert "Body (HTML)" in body  # Shopify dialect notes present
        assert "`Handle`" in body  # canonical columns present
 def test_export_returns_canonical_csv(fresh_db_url):
    with _merchant_client(fresh_db_url) as client:
        draft = _upload(client).json()
@@ -77,3 +77,25 @@ def test_apply_failure_rolls_back_whole_transaction_tel6(migrated_conn, monkeypa
    assert migrated_conn.execute("SELECT count(*) FROM import_draft").fetchone()[0] == 1
    events = [json.loads(r.message) for r in caplog.records if r.name == "ecomm.telemetry"]
    assert any(e["event"] == "import_apply_failed" and e["error_class"] == "RuntimeError" for e in events)
 # A partial Shopify export (signature: Body (HTML) + Variant Grams) naming only one
 # of the two existing products — INV-10 must hold across the dialect boundary.
 SHOPIFY_PARTIAL = (
    b"Handle,Title,Body (HTML),Variant Price,Variant Grams\n"
    b"mug,Mug,<p>x</p>,12.00,180\n"
 )
 def test_inv10_shopify_partial_never_deletes(migrated_conn):
    acct, sf = _merchant(migrated_conn)
    _import(migrated_conn, acct, sf, CSV_A)
    before = migrated_conn.execute("SELECT count(*) FROM product").fetchone()[0]
    d = products.import_validate(migrated_conn, sf, acct, "shopify.csv", SHOPIFY_PARTIAL)
    assert d["dialect"] == "shopify"
    products.confirm_draft(migrated_conn, sf, acct, d["id"])
    after = migrated_conn.execute("SELECT count(*) FROM product").fetchone()[0]
    # INV-10: nothing deleted; the unmentioned 'tee' is untouched.
    assert after >= before == 2
    handles = {r[0] for r in migrated_conn.execute("SELECT handle FROM product").fetchall()}
    assert {"mug", "tee"} <= handles
@@ -60,6 +60,47 @@ Option names live both in `CanonicalProduct.option_names` (the values) and in
 `fields{}` (the file-presence marker the diff needs for the absent-vs-clear
 distinction).
 ## Dialects (INV-17, SLICE-8)
 A file is normalized to canonical names **at the codec boundary**, so every stage
 downstream of `parse_csv` (validate → diff → apply) is dialect-agnostic — it only
 ever sees canonical cells. Two dialects exist: `canonical` and `shopify`.
 `dialect_shopify.py` is the Shopify adapter and the source of truth for the
 mapping (mirrored by `tests/test_products_dialect_shopify.py` and
 `tests/fixtures/shopify-export.csv`):
 - **Detection** — `is_shopify_header()` returns `shopify` iff the header carries a
  Shopify-only *signature* column (`Body (HTML)`, `Variant Grams`, `Cost per item`,
  `Gift Card`, a `Google Shopping / …` column, …) **and no canonical-distinctive
  column**. A canonical-distinctive name — one Shopify renames away (`Description`,
  `Variant Cost`, `Variant Weight`, `Google Product Category`) or a canonical-only
  column Shopify lacks (`Variant Volume`, `Variant Tax ID 1/2`, `Variant Position`) —
  **vetoes** Shopify detection. Detection is by signature, not an exact header set, so
  extra market/region columns don't defeat it; the veto biases it conservative, because
  under-detection is safe (Shopify-named columns are warned as not-imported) while
  over-detection corrupts (canonical `Type` / `Variant Weight Unit` would be dropped).
  So a hybrid or ambiguous header falls through to `canonical`, which maps shared
  columns identically and warns the rest — it never misparses (§7.4).
 - **Mapping** — `map_shopify_header(header)` returns `(mapped, not_imported)`:
  `mapped[i]` is the canonical name for column `i` (or `None` when it has no
  canonical home), and `not_imported` is the warning list surfaced as the draft's
  `unknown_columns`. The rule per column, in order: in `SHOPIFY_RENAME` →
  canonical name; in `SHOPIFY_DROP` (`Type`, `Variant Weight Unit`) → not imported;
  in `KNOWN_COLUMNS` → pass through; else → not imported (this last branch absorbs
  the unbounded `… / <Market>` price columns without enumerating them).
 - **The two name-collision overrides** are why `SHOPIFY_DROP` exists: Shopify's
  `Type` is a free-text category, but canonical `Type` is *structural*
  (`standalone`/kits), so it is warned rather than folded in; and Shopify's
  `Variant Weight Unit` is dropped because the `Variant Grams` → `Variant Weight`
  rename is the weight source.
 - **The one value transform** lives in `parse_csv`: when a Shopify row has a mapped
  `Variant Weight` (from `Variant Grams`), the codec synthesizes
  `Variant Weight Unit = "g"`, since Shopify grams are unitless integers.
 `detect_dialect()` in `codec.py` is the INV-17 seam; a new dialect is a new adapter
 module plus a branch there, with no change to validate/diff/apply.
 ## Error granularity
 `validate.py` never raises on a row problem: every violation is recorded as a
@@ -0,0 +1,721 @@
 # SLICE-8 — Shopify dialect + public format docs — Implementation Plan
 > **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
 **Goal:** Auto-detect a Shopify product-CSV export by its header set, map it to the canonical model at the codec boundary (INV-17), warn (not fail) on Shopify columns with no canonical home, and publish the public column reference (DOC-2) + finalized sample CSV (DOC-3) — completing PUC-6 (a Shopify export imports directly) and PUC-11 (learning the format).
 **Architecture:** A Shopify file is recognized by *signature columns* it carries that canonical never does (`Body (HTML)`, `Variant Grams`, `Cost per item`, `Google Shopping / *`, …). Detected Shopify headers are rewritten to canonical names *before* the existing known/unknown split in `parse_csv`, so every downstream stage (validate → diff → apply) is already dialect-agnostic and unchanged (INV-17). Shopify columns with no canonical home — including two name-collision overrides (`Type` is Shopify's *free-text* type vs canonical's *structural* type; `Variant Weight Unit` is superseded by the grams→weight transform) — flow into the existing `unknown_columns` warning, which the preview UI already renders. The only value transform is `Variant Grams` → canonical `Variant Weight` (+ synthesized unit `g`). Frontend is already built for dialect display and the not-imported banner; SLICE-8 only sharpens the label and the upload-screen format help, and adds DOC-2.
 **Tech Stack:** Python 3.13 / FastAPI backend (`backend/app/domains/products/`), Vitest + React/TS SPA (`frontend/src/`), Playwright E2E (`e2e/`). Tests: `pytest` (backend), `npm test` (frontend), `scripts/e2e.sh` (browser).
 ---
 ## The exhaustive Shopify → canonical mapping (the §6.5.1 fixture)
 This table is the contract. It is pinned as a Python literal in Task 1 and as a CSV fixture in Task 3.
 **Mapped — renamed** (Shopify header → canonical header):
 | Shopify column | Canonical column | Note |
 | --- | --- | --- |
 | `Body (HTML)` | `Description` | HTML, sanitized downstream (INV-15) |
 | `Product Category` | `Google Product Category` | taxonomy string |
 | `Cost per item` | `Variant Cost` | decimal |
 | `Variant Grams` | `Variant Weight` | value transform: grams numeric; unit `g` synthesized |
 **Mapped — direct** (same name, already in `KNOWN_COLUMNS`, pass through): `Handle`, `Title`, `Vendor`, `Tags`, `Published`, `Status`, `Option1 Name`, `Option2 Name`, `Option3 Name`, `Option1 Value`, `Option2 Value`, `Option3 Value`, `Variant SKU`, `Variant Barcode`, `Variant Price`, `Variant Inventory Tracker`, `Variant Inventory Qty`, `Variant Image`, `Image Src`, `Image Position`, `Image Alt Text`.
 **Not imported — warned** (no canonical home; surfaced in `unknown_columns`):
 - **Name-collision overrides (must NOT pass through):**
  - `Type` — Shopify free-text type; canonical `Type` is structural (`standalone`/kits, #15). Per decision D (spec §11): warned, never folded into canonical `Type` or `Tags`.
  - `Variant Weight Unit` — superseded by the `Variant Grams` → weight transform (unit forced to `g`).
 - **Shopify-only columns:** `Variant Compare At Price` (a.k.a. `Compare At Price`), `Variant Inventory Policy`, `Variant Fulfillment Service`, `Variant Requires Shipping`, `Variant Taxable`, `Variant Tax Code`, `Gift Card`, `SEO Title`, `SEO Description`, every `Google Shopping / *` column, and any market/region column (`Included / *`, `Price / *`, `Compare At Price / *`, `Price / International`, …).
 **Algorithm (handles the unbounded market columns without enumerating them):** for each header column, in order —
 1. in `SHOPIFY_RENAME` → its canonical name (mapped);
 2. in `SHOPIFY_DROP` overrides (`{"Type", "Variant Weight Unit"}`) → not imported;
 3. else in `KNOWN_COLUMNS` → pass through (mapped);
 4. else → not imported.
 **Detection signature** — a header is Shopify iff it contains ≥1 column canonical never has:
 `{"Body (HTML)", "Variant Grams", "Cost per item", "Variant Compare At Price", "Variant Inventory Policy", "Variant Fulfillment Service", "Variant Requires Shipping", "Variant Taxable", "Gift Card", "SEO Title", "SEO Description"}` **or** any column starting `"Google Shopping / "`. Otherwise canonical (the safe default — shared columns map identically, so an ambiguous file never misparses; §7.4 risk row).
 ---
 ## File structure
 - **Create** `backend/app/domains/products/dialect_shopify.py` — detection + header mapping + the pinned table. One responsibility: the Shopify adapter.
 - **Modify** `backend/app/domains/products/codec.py` — `detect_dialect()` calls the adapter; `parse_csv()` rewrites the header before the known/unknown split and synthesizes the weight unit.
 - **Create** `backend/tests/test_products_dialect_shopify.py` — adapter unit tests + the exhaustive-mapping fixture test.
 - **Modify** `backend/tests/test_products_codec.py` — detection + end-to-end parse-as-shopify tests.
 - **Modify** `backend/tests/test_products_invariants.py` — INV-10 over a partial Shopify file.
 - **Create** `backend/app/domains/products/columns.md` — DOC-2 source (column reference, every column + dialect notes).
 - **Modify** `backend/app/main.py` — add `GET /api/products/columns.md`.
 - **Modify** `backend/tests/test_products_api.py` (or the existing API test module) — route test for DOC-2.
 - **Modify** `frontend/src/productsApi.ts` — `dialectLabel("shopify")` → `"Shopify product CSV — mapped"`.
 - **Modify** `frontend/src/screens/products/ImportUpload.tsx` — format help mentions Shopify + links DOC-2.
 - **Modify** `frontend/src/screens/products/ProductsPage.tsx` — link DOC-2 beside the sample CSV.
 - **Modify** `frontend/src/productsApi.test.ts` (or create) — `dialectLabel` cases.
 - **Create** `e2e/fixtures/shopify-export.csv` — an unmodified-shape Shopify export fixture.
 - **Create** `e2e/tests/import-shopify-dialect.spec.ts` — `e2e_import_shopify_dialect`.
 - **Modify** `docs/products-domain.md` — DOC-4 dialect-adapter notes.
 - **Modify** `backend/app/__init__.py` (or wherever `__version__`/`app.json` version lives) + `CHANGELOG`/version bump to v0.8.0.
 ---
 ### Task 1: Shopify dialect adapter module
 **Files:**
 - Create: `backend/app/domains/products/dialect_shopify.py`
 - Test: `backend/tests/test_products_dialect_shopify.py`
 - [ ] **Step 1: Write the failing tests**
 ```python
 # backend/tests/test_products_dialect_shopify.py
 from app.domains.products.dialect_shopify import is_shopify_header, map_shopify_header
 def test_detects_shopify_by_signature_column():
    assert is_shopify_header(["Handle", "Title", "Body (HTML)", "Variant Price"]) is True
    assert is_shopify_header(["Handle", "Title", "Google Shopping / MPN"]) is True
 def test_canonical_header_is_not_shopify():
    assert is_shopify_header(["Handle", "Title", "Description", "Variant Cost"]) is False
 def test_ambiguous_shared_only_header_defaults_canonical():
    # Only columns common to both dialects -> not Shopify (safe default, never misparse).
    assert is_shopify_header(["Handle", "Title", "Option1 Name", "Variant Price", "Image Src"]) is False
 def test_map_renames_and_passes_through():
    mapped, not_imported = map_shopify_header(
        ["Handle", "Body (HTML)", "Cost per item", "Variant Price"]
    )
    assert mapped == ["Handle", "Description", "Variant Cost", "Variant Price"]
    assert not_imported == []
 def test_map_drops_type_and_weight_unit_overrides():
    mapped, not_imported = map_shopify_header(
        ["Handle", "Type", "Variant Grams", "Variant Weight Unit"]
    )
    assert mapped == ["Handle", None, "Variant Weight", None]
    assert not_imported == ["Type", "Variant Weight Unit"]
 def test_map_drops_shopify_only_and_market_columns():
    mapped, not_imported = map_shopify_header(
        ["Handle", "Variant Compare At Price", "Gift Card", "Price / International"]
    )
    assert mapped == ["Handle", None, None, None]
    assert not_imported == ["Variant Compare At Price", "Gift Card", "Price / International"]
 ```
 - [ ] **Step 2: Run to verify it fails**
 Run: `cd backend && python -m pytest tests/test_products_dialect_shopify.py -v`
 Expected: FAIL — `ModuleNotFoundError: app.domains.products.dialect_shopify`
 - [ ] **Step 3: Implement the adapter**
 ```python
 # backend/app/domains/products/dialect_shopify.py
 """Shopify product-CSV adapter (INV-17): detect by header signature, map to canonical.
 The mapping is the §6.5.1 contract; the exhaustive table is pinned here and
 mirrored by tests/test_products_dialect_shopify.py + e2e/fixtures/shopify-export.csv.
 """
 from __future__ import annotations
 from .models import KNOWN_COLUMNS
 # Shopify header -> canonical header (renames only; direct same-name columns pass
 # through via KNOWN_COLUMNS). Variant Grams carries a value transform (see codec).
 SHOPIFY_RENAME: dict[str, str] = {
    "Body (HTML)": "Description",
    "Product Category": "Google Product Category",
    "Cost per item": "Variant Cost",
    "Variant Grams": "Variant Weight",
 }
 # Canonical-named columns Shopify uses differently — must NOT pass through.
 SHOPIFY_DROP: frozenset[str] = frozenset({"Type", "Variant Weight Unit"})
 # Columns whose presence proves the file is a Shopify export (canonical never has them).
 _SIGNATURE: frozenset[str] = frozenset({
    "Body (HTML)", "Variant Grams", "Cost per item", "Variant Compare At Price",
    "Variant Inventory Policy", "Variant Fulfillment Service",
    "Variant Requires Shipping", "Variant Taxable", "Gift Card",
    "SEO Title", "SEO Description",
 })
 def is_shopify_header(header: list[str]) -> bool:
    cols = {h.strip() for h in header}
    if cols & _SIGNATURE:
        return True
    return any(c.startswith("Google Shopping / ") for c in cols)
 def map_shopify_header(header: list[str]) -> tuple[list[str | None], list[str]]:
    """Return (mapped, not_imported): mapped[i] is the canonical name for header[i],
    or None when that Shopify column has no canonical home; not_imported lists the
    original Shopify names (in order) that were dropped — the preview warning."""
    mapped: list[str | None] = []
    not_imported: list[str] = []
    for raw in header:
        col = raw.strip()
        if col in SHOPIFY_RENAME:
            mapped.append(SHOPIFY_RENAME[col])
        elif col in SHOPIFY_DROP:
            mapped.append(None)
            not_imported.append(col)
        elif col in KNOWN_COLUMNS:
            mapped.append(col)
        else:
            mapped.append(None)
            if col:
                not_imported.append(col)
    return mapped, not_imported
 ```
 - [ ] **Step 4: Run to verify it passes**
 Run: `cd backend && python -m pytest tests/test_products_dialect_shopify.py -v`
 Expected: PASS (6 tests)
 - [ ] **Step 5: Commit**
 ```bash
 git add backend/app/domains/products/dialect_shopify.py backend/tests/test_products_dialect_shopify.py
 git commit -m "feat(products): Shopify dialect adapter — header detection + canonical mapping (SD-0002 §6.5.1, SLICE-8)"
 ```
 ---
 ### Task 2: Wire the adapter into the codec
 **Files:**
 - Modify: `backend/app/domains/products/codec.py:15-66`
 - Test: `backend/tests/test_products_codec.py`
 - [ ] **Step 1: Write the failing tests** (append to `test_products_codec.py`)
 ```python
 def test_parse_detects_and_maps_shopify():
    data = (
        "Handle,Title,Body (HTML),Cost per item,Variant Price,Variant Grams,Type,Gift Card\n"
        "mug,Moon Mug,<p>Grey</p>,9.50,18.00,300,Drinkware,false\n"
    ).encode("utf-8")
    parsed = parse_csv(data)
    assert parsed.dialect == "shopify"
    cells = parsed.rows[0].cells
    assert cells["Description"] == "<p>Grey</p>"
    assert cells["Variant Cost"] == "9.50"
    assert cells["Variant Weight"] == "300"
    assert cells["Variant Weight Unit"] == "g"   # synthesized
    # Type (free-text) and Gift Card warned, never mapped:
    assert "Type" in parsed.unknown_columns
    assert "Gift Card" in parsed.unknown_columns
    assert "product_type" not in str(cells)  # Type never reached canonical
 def test_parse_canonical_unchanged():
    data = b"Handle,Title,Description,Variant Price\nmug,Moon Mug,Grey,18.00\n"
    parsed = parse_csv(data)
    assert parsed.dialect == "canonical"
    assert parsed.rows[0].cells["Description"] == "Grey"
    assert parsed.unknown_columns == []
 ```
 - [ ] **Step 2: Run to verify it fails**
 Run: `cd backend && python -m pytest tests/test_products_codec.py -k "shopify or canonical_unchanged" -v`
 Expected: FAIL — `parsed.dialect == "canonical"` (detection still stubbed) / `KeyError: 'Description'`
 - [ ] **Step 3: Rewrite `detect_dialect` + `parse_csv`** in `codec.py`
 Replace the `detect_dialect` stub and the header/cell-building block. New `codec.py` (lines from the import down through `parse_csv`):
 ```python
 from .dialect_shopify import is_shopify_header, map_shopify_header
 from .models import KNOWN_COLUMNS, MAX_DATA_ROWS, MAX_FILE_BYTES, ParsedFile, Row
 _REQUIRED_HEADER_COLUMNS = ("Handle", "Title")
 def detect_dialect(header: list[str]) -> str:
    """The INV-17 seam: recognize Shopify's header set, else canonical (§6.5.1)."""
    return "shopify" if is_shopify_header(header) else "canonical"
 def parse_csv(data: bytes) -> ParsedFile:
    if len(data) > MAX_FILE_BYTES:
        raise FileRejected("file_too_large", "This file is larger than 10 MB.")
    try:
        text = data.decode("utf-8-sig")
    except UnicodeDecodeError:
        raise FileRejected("not_csv", "This file isn't readable as CSV.") from None
    reader = csv.reader(io.StringIO(text))
    try:
        try:
            raw_header = next(reader)
        except StopIteration:
            raise FileRejected("not_csv", "This file isn't readable as CSV.") from None
        header = [h.strip() for h in raw_header]
        dialect = detect_dialect(header)
        # INV-17: normalize the header to canonical names at the boundary. For Shopify,
        # mapped[i] is the canonical name (or None when dropped); not_imported is the
        # warning list. Canonical files map to themselves, unknowns warned as before.
        if dialect == "shopify":
            mapped, unknown = map_shopify_header(header)
        else:
            mapped = [c if c in KNOWN_COLUMNS else None for c in header]
            unknown = [c for c in header if c and c not in KNOWN_COLUMNS]
        for col in _REQUIRED_HEADER_COLUMNS:
            if col not in (mapped):
                raise FileRejected(
                    "missing_required_column",
                    f"This file is missing the required column '{col}'.",
                )
        # First occurrence of a duplicated canonical column wins.
        col_index: dict[str, int] = {}
        for i, name in enumerate(mapped):
            if name and name not in col_index:
                col_index[name] = i
        # De-dup the warning list, order-preserving.
        seen: set[str] = set()
        unknown = [c for c in unknown if not (c in seen or seen.add(c))]
        rows: list[Row] = []
        for raw in reader:
            if not any(cell.strip() for cell in raw):
                continue
            if len(rows) >= MAX_DATA_ROWS:
                raise FileRejected(
                    "too_many_rows",
                    f"This file has more than {MAX_DATA_ROWS:,} rows — split it and import in parts.",
                )
            cells = {
                c: (raw[col_index[c]].strip() if col_index[c] < len(raw) else "")
                for c in col_index
            }
            # Shopify grams carry an implicit unit; canonical needs it explicit (§6.5.1).
            if dialect == "shopify" and cells.get("Variant Weight"):
                cells["Variant Weight Unit"] = "g"
            rows.append(Row(line_number=reader.line_num, cells=cells))
    except csv.Error:
        raise FileRejected("not_csv", "This file isn't readable as CSV.") from None
    return ParsedFile(dialect=dialect, header=header, unknown_columns=unknown, rows=rows)
 ```
 Note: the required-column check now reads `mapped` (canonical names) so a Shopify file whose `Title`/`Handle` are present passes, and a file genuinely missing them still fails honestly. `Handle` and `Title` are direct pass-through names in both dialects, so `mapped` contains them when present.
 - [ ] **Step 4: Run to verify it passes**
 Run: `cd backend && python -m pytest tests/test_products_codec.py -v`
 Expected: PASS (existing canonical tests + 2 new)
 - [ ] **Step 5: Run the whole products suite (no regressions)**
 Run: `cd backend && python -m pytest tests/ -q`
 Expected: PASS — validate/diff/invariants unchanged (they consume canonical cells; INV-17 holds).
 - [ ] **Step 6: Commit**
 ```bash
 git add backend/app/domains/products/codec.py backend/tests/test_products_codec.py
 git commit -m "feat(products): codec detects + maps Shopify dialect at the boundary (INV-17, SLICE-8)"
 ```
 ---
 ### Task 3: Exhaustive-mapping fixture test (the §6.5.1 pin)
 **Files:**
 - Create: `backend/tests/fixtures/shopify-export.csv`
 - Test: `backend/tests/test_products_dialect_shopify.py` (append)
 - [ ] **Step 1: Create a realistic full-width Shopify export fixture**
 `backend/tests/fixtures/shopify-export.csv` — one product, two variants, one image-only row, exercising every mapped + several not-imported columns:
 ```csv
 Handle,Title,Body (HTML),Vendor,Product Category,Type,Tags,Published,Status,Option1 Name,Option1 Value,Variant SKU,Variant Grams,Variant Inventory Tracker,Variant Inventory Qty,Variant Inventory Policy,Variant Fulfillment Service,Variant Price,Variant Compare At Price,Variant Requires Shipping,Variant Taxable,Variant Barcode,Image Src,Image Position,Image Alt Text,Gift Card,SEO Title,SEO Description,Google Shopping / MPN,Variant Image,Variant Weight Unit,Cost per item,Status
 star-tee,Star Tee,<p>Soft cotton tee.</p>,Wiggle Goods,Apparel & Accessories > Clothing,Shirts,"apparel, tees",TRUE,active,Size,S,WG-TEE-S,180,shopify,12,deny,manual,24.00,30.00,TRUE,TRUE,0001,https://img.example.com/star-tee.jpg,1,Star Tee,FALSE,Star Tee | Wiggle,Soft tee,MPN-1,https://img.example.com/star-s.jpg,g,11.00,active
 star-tee,,,,,,,,,,M,WG-TEE-M,180,shopify,18,deny,manual,24.00,30.00,TRUE,TRUE,0002,,,,FALSE,,,,,g,11.00,
 star-tee,,,,,,,,,,,,,,,,,,,,,,https://img.example.com/star-back.jpg,2,Star Tee back,,,,,,,,
 ```
 - [ ] **Step 2: Write the failing test**
 ```python
 import csv as _csv
 import io
 from pathlib import Path
 from app.domains.products.codec import parse_csv
 _FIXTURE = Path(__file__).parent / "fixtures" / "shopify-export.csv"
 def test_shopify_fixture_maps_exhaustively():
    parsed = parse_csv(_FIXTURE.read_bytes())
    assert parsed.dialect == "shopify"
    first = parsed.rows[0].cells
    # renamed
    assert first["Description"] == "<p>Soft cotton tee.</p>"
    assert first["Google Product Category"] == "Apparel & Accessories > Clothing"
    assert first["Variant Cost"] == "11.00"
    assert first["Variant Weight"] == "180"
    assert first["Variant Weight Unit"] == "g"
    # direct
    assert first["Variant SKU"] == "WG-TEE-S"
    assert first["Image Src"] == "https://img.example.com/star-tee.jpg"
    # not imported — warned, none leaked into canonical cells
    for col in ("Type", "Variant Compare At Price", "Gift Card", "SEO Title",
                "Google Shopping / MPN", "Variant Weight Unit", "Variant Inventory Policy",
                "Variant Fulfillment Service", "Variant Requires Shipping", "Variant Taxable"):
        assert col in parsed.unknown_columns, col
    assert "Variant Compare At Price" not in first
 ```
 - [ ] **Step 3: Run — expect PASS** (codec from Task 2 already maps correctly)
 Run: `cd backend && python -m pytest tests/test_products_dialect_shopify.py::test_shopify_fixture_maps_exhaustively -v`
 Expected: PASS. If a column assertion fails, fix the mapping table in `dialect_shopify.py` to match this fixture — the fixture and table must agree.
 - [ ] **Step 4: Commit**
 ```bash
 git add backend/tests/fixtures/shopify-export.csv backend/tests/test_products_dialect_shopify.py
 git commit -m "test(products): exhaustive Shopify->canonical mapping fixture (SD-0002 §6.5.1, SLICE-8)"
 ```
 ---
 ### Task 4: INV-10 over a partial Shopify import (never deletes)
 **Files:**
 - Test: `backend/tests/test_products_invariants.py` (append)
 - [ ] **Step 1: Inspect the existing INV-10 test** to reuse its catalog/diff helpers
 Run: `cd backend && grep -n "def test_inv10\|compute_diff\|build_products\|catalog" tests/test_products_invariants.py | head`
 Expected: shows the helper pattern (catalog fixture → parse → build_products → compute_diff → assert no deletes in plan).
 - [ ] **Step 2: Write the failing test** (mirror the existing INV-10 test, swapping in a Shopify file that omits an existing product)
 ```python
 def test_inv10_shopify_partial_never_deletes():
    # An existing catalog of two products; a Shopify file mentioning only one.
    catalog = _catalog_with(["star-tee", "moon-mug"])  # existing helper
    data = (
        "Handle,Title,Body (HTML),Variant Price,Variant Grams\n"
        "star-tee,Star Tee,<p>x</p>,24.00,180\n"
    ).encode("utf-8")
    parsed = parse_csv(data)
    assert parsed.dialect == "shopify"
    products = build_products(parsed)
    result = compute_diff(catalog, products)
    # INV-10: nothing in the plan deletes; moon-mug (unmentioned) is untouched.
    assert all(op.kind != "delete" for op in result.plan)
    assert "moon-mug" not in {p.handle for p in products}
 ```
 Adapt `_catalog_with` / `op.kind` / `result.plan` to the actual symbols found in Step 1.
 - [ ] **Step 3: Run to verify it passes**
 Run: `cd backend && python -m pytest tests/test_products_invariants.py -k inv10_shopify -v`
 Expected: PASS (INV-10 is dialect-agnostic; this proves it over Shopify).
 - [ ] **Step 4: Commit**
 ```bash
 git add backend/tests/test_products_invariants.py
 git commit -m "test(products): INV-10 holds over a partial Shopify import (SLICE-8)"
 ```
 ---
 ### Task 5: Frontend — Shopify label + format help
 **Files:**
 - Modify: `frontend/src/productsApi.ts:52-54`
 - Modify: `frontend/src/screens/products/ImportUpload.tsx:53`
 - Modify: `frontend/src/screens/products/ProductsPage.tsx:114`
 - Test: `frontend/src/productsApi.test.ts`
 - [ ] **Step 1: Write the failing test** (create or append `frontend/src/productsApi.test.ts`)
 ```ts
 import { describe, expect, it } from "vitest";
 import { dialectLabel } from "./productsApi";
 describe("dialectLabel", () => {
  it("labels canonical", () => expect(dialectLabel("canonical")).toBe("Canonical format"));
  it("labels shopify as mapped", () =>
    expect(dialectLabel("shopify")).toBe("Shopify product CSV — mapped"));
 });
 ```
 - [ ] **Step 2: Run to verify it fails**
 Run: `cd frontend && npm test -- productsApi`
 Expected: FAIL — receives `"shopify"`, expected `"Shopify product CSV — mapped"`.
 - [ ] **Step 3: Update `dialectLabel`**
 ```ts
 // frontend/src/productsApi.ts
 export function dialectLabel(d: string): string {
  if (d === "canonical") return "Canonical format";
  if (d === "shopify") return "Shopify product CSV — mapped";
  return d;
 }
 ```
 - [ ] **Step 4: Run to verify it passes**
 Run: `cd frontend && npm test -- productsApi`
 Expected: PASS
 - [ ] **Step 5: Update the upload-screen format help** — `ImportUpload.tsx:53`
 Replace the line `Works with the canonical format.{" "}` and the following sample link block so it reads (PUC-11, §5.4 wireframe text):
 ```tsx
        Works with the canonical format or a Shopify product CSV.{" "}
        <a href="/api/products/sample.csv" download>
          Download a sample
        </a>{" "}
        ·{" "}
        <a href="/api/products/columns.md" target="_blank" rel="noopener">
          Column reference
        </a>
 ```
 - [ ] **Step 6: Add the column-reference link beside the sample on the Products page** — `ProductsPage.tsx:114`
 After the existing `<a href="/api/products/sample.csv" download>` element, add:
 ```tsx
            {" · "}
            <a href="/api/products/columns.md" target="_blank" rel="noopener">
              Column reference
            </a>
 ```
 - [ ] **Step 7: Build + typecheck + test**
 Run: `cd frontend && npm run build && npm test`
 Expected: PASS (no TS errors, vitest green).
 - [ ] **Step 8: Commit**
 ```bash
 git add frontend/src/productsApi.ts frontend/src/productsApi.test.ts frontend/src/screens/products/ImportUpload.tsx frontend/src/screens/products/ProductsPage.tsx
 git commit -m "feat(products-ui): Shopify 'mapped' label + format help links to column reference (PUC-6/PUC-11, SLICE-8)"
 ```
 ---
 ### Task 6: DOC-2 column reference + route; finalize DOC-3
 **Files:**
 - Create: `backend/app/domains/products/columns.md`
 - Modify: `backend/app/main.py` (after the `sample.csv` route, ~line 451)
 - Modify: `backend/app/domains/products/__init__.py` (export `COLUMNS_MD_PATH` next to `SAMPLE_CSV_PATH`)
 - Test: the existing products API test module (find it in Step 4)
 - [ ] **Step 1: Write the DOC-2 column reference** — `backend/app/domains/products/columns.md`
 A complete merchant-facing reference: a short intro (canonical = Shopify-flavored superset; auto-detection; blank-vs-absent semantics), then a table of **every canonical column** (name · level · required · accepted values), then a **Shopify dialect notes** section reproducing the Task-1 mapping table (renamed, direct, not-imported). Source the canonical column rows from spec §6.5.1 (the table at lines 852-873) and the dialect notes from §6.5.1 (lines 880-889). Keep it plain Markdown — no app-specific build step.
 - [ ] **Step 2: Export the path** — `backend/app/domains/products/__init__.py`
 Add beside the existing `SAMPLE_CSV_PATH`:
 ```python
 COLUMNS_MD_PATH = _HERE / "columns.md"
 ```
 (Use the same `_HERE` / `Path(__file__).parent` idiom already present for `SAMPLE_CSV_PATH`.)
 - [ ] **Step 3: Add the route** — `backend/app/main.py`, immediately after `products_sample_csv`
 ```python
    @app.get("/api/products/columns.md")
    def products_columns_md():
        """The DOC-2 column reference. Documentation, so no auth gate (§6.4)."""
        return PlainTextResponse(
            products.COLUMNS_MD_PATH.read_text(),
            media_type="text/markdown; charset=utf-8",
        )
 ```
 - [ ] **Step 4: Write the failing route test** — find the API test module first
 Run: `cd backend && ls tests/ | grep -i "api\|main"`
 Append to the module that tests the other unauthenticated doc routes:
 ```python
 def test_columns_md_served(client):
    resp = client.get("/api/products/columns.md")
    assert resp.status_code == 200
    assert "text/markdown" in resp.headers["content-type"]
    body = resp.text
    assert "Body (HTML)" in body          # dialect notes present
    assert "Handle" in body               # canonical columns present
 ```
 - [ ] **Step 5: Run to verify it passes**
 Run: `cd backend && python -m pytest tests/ -k "columns_md or sample" -v`
 Expected: PASS
 - [ ] **Step 6: Verify DOC-3 sample.csv is final** — it already carries a variant product (`star-tee`, S/M/L) and image rows. Confirm it parses clean as canonical:
 Run: `cd backend && python -c "from app.domains.products.codec import parse_csv; from app.domains.products import SAMPLE_CSV_PATH; p=parse_csv(SAMPLE_CSV_PATH.read_bytes()); print(p.dialect, len(p.rows), p.unknown_columns)"`
 Expected: `canonical 5 []` (no unknown columns; 5 data rows). If `unknown_columns` is non-empty, fix the sample header to canonical names.
 - [ ] **Step 7: Commit**
 ```bash
 git add backend/app/domains/products/columns.md backend/app/domains/products/__init__.py backend/app/main.py backend/tests/
 git commit -m "docs(products): DOC-2 column reference served at /api/products/columns.md (SLICE-8)"
 ```
 ---
 ### Task 7: DOC-4 dialect-adapter dev notes
 **Files:**
 - Modify: `docs/products-domain.md`
 - [ ] **Step 1: Add a "Dialects (INV-17)" subsection** documenting: detection by signature columns; the `dialect_shopify` adapter; the rename/drop/passthrough algorithm; the grams→weight transform; that all downstream stages are dialect-agnostic. Point to `dialect_shopify.py` and the fixture as the source of truth (documentation-leads-automation, §4.1).
 - [ ] **Step 2: Commit**
 ```bash
 git add docs/products-domain.md
 git commit -m "docs(products): DOC-4 dialect-adapter notes (SLICE-8)"
 ```
 ---
 ### Task 8: E2E — `e2e_import_shopify_dialect`
 **Files:**
 - Create: `e2e/fixtures/shopify-export.csv` (copy the Task-3 fixture)
 - Create: `e2e/tests/import-shopify-dialect.spec.ts`
 - [ ] **Step 1: Add the fixture** — same content as `backend/tests/fixtures/shopify-export.csv`.
 - [ ] **Step 2: Read an existing import E2E spec** to reuse the sign-up + upload helpers
 Run: `sed -n '1,60p' e2e/tests/import-preview-confirm.spec.ts`
 Expected: shows the page-object / sign-up helper and the upload→preview→confirm flow to mirror.
 - [ ] **Step 3: Write `e2e/tests/import-shopify-dialect.spec.ts`** (mirroring that helper)
 ```ts
 import { test, expect } from "@playwright/test";
 import { signUpAndOpenImport } from "./helpers";  // use the actual helper from Step 2
 test("e2e_import_shopify_dialect: a Shopify export imports directly (PUC-6)", async ({ page }) => {
  await signUpAndOpenImport(page);
  await page.getByLabel(/choose|upload|file/i).setInputFiles("fixtures/shopify-export.csv");
  // Preview shows the mapped banner + not-imported warning
  await expect(page.getByText("Shopify product CSV — mapped")).toBeVisible();
  await expect(page.getByText(/not imported/i)).toBeVisible();
  await expect(page.getByText("Type")).toBeVisible();        // a warned column
  // Confirm and land on the run detail
  await page.getByRole("button", { name: /^Import \d/ }).click();
  await expect(page).toHaveURL(/\/products\/imports\/runs\/\d+/);
  await expect(page.getByText("Shopify product CSV — mapped")).toBeVisible();
 });
 ```
 Adapt selectors to the real upload control + helper names found in Step 2.
 - [ ] **Step 4: Run the E2E suite**
 Run: `./scripts/e2e.sh`
 Expected: all specs PASS including `import-shopify-dialect` (7 prior + 1 new = 8).
 - [ ] **Step 5: Commit**
 ```bash
 git add e2e/fixtures/shopify-export.csv e2e/tests/import-shopify-dialect.spec.ts
 git commit -m "test(e2e): e2e_import_shopify_dialect — Shopify export imports directly (PUC-6, SLICE-8)"
 ```
 ---
 ### Task 9: Traceability audit, version bump, full green
 **Files:**
 - Modify: version source (`backend/app/__init__.py` or `app.json`) + any `CHANGELOG`
 - Read-only: spec §12 traceability matrix
 - [ ] **Step 1: Audit §12 traceability** — confirm PUC-6, PUC-11, BUC-1 (Shopify), DOC-2, DOC-3 now have shipping code + tests. Note any gap in the transcript `## Deferred decisions`. (Spec audit is read-only; do not edit the content repo here — finalize submits the plan.)
 - [ ] **Step 2: Bump the version to v0.8.0**
 Run: `cd backend && grep -rn "0.7.0" app/__init__.py app.json 2>/dev/null`
 Update the version string to `0.8.0` wherever the prior slice set it (mirror the SLICE-7 v0.7.0 bump).
 - [ ] **Step 3: Full local gate**
 Run: `./scripts/check.sh && ./scripts/e2e.sh` (or the repo's canonical localhost gate)
 Expected: backend pytest, frontend build+vitest, import-linter, and Playwright all PASS.
 - [ ] **Step 4: Commit**
 ```bash
 git add -A
 git commit -m "chore(products): SLICE-8 complete — bump v0.8.0; §12 traceability audited (SD-0002)"
 ```
 ---
 ## Post-plan (session flow, not subagent tasks)
 After all tasks are green on the branch:
 1. **PR → merge to `main`** (branch→PR→merge; §5.4).
 2. **PPE deploy** via flotilla + E2E green on `https://ecomm-ppe.wiggleverse.org`; stamp the `release/<ts>` tag (§9.1). Prod promotion stays the operator's gate.
 3. **Close story #13** (SLICE-5/6/7/8 all done) with a pointer to the merge + PPE release tag.
 4. **Finalize** the session (`wgl-session-finalize`) — archives this plan to the content repo `plans/`, updates memory, publishes the transcript.
 ---
 ## Self-Review
 **Spec coverage (SLICE-8 §7.2 DoD):**
 - Header-set dialect detection → Task 1 (`is_shopify_header`) + Task 2 (`detect_dialect`). ✓
 - Shopify→canonical mapping + exhaustive fixture → Task 1 (table) + Task 3 (fixture pin). ✓
 - Preview "mapped" banner + not-imported warnings → Task 5 (label) + already-built `unknown_columns` banner (`ImportPreview.tsx:288`). ✓
 - DOC-2 column reference (published) → Task 6. ✓
 - DOC-3 final sample CSV → Task 6 Step 6 (verify; already has variants+images). ✓
 - `e2e_import_shopify_dialect` green → Task 8. ✓
 - BUC-1 acceptance for an unmodified Shopify export → Task 3 fixture + Task 8 E2E. ✓
 - §12 traceability audited → Task 9. ✓
 - INV-10 over Shopify → Task 4. ✓
 **Placeholder scan:** every code step shows concrete code; selectors/helpers in Tasks 4/6/8 are explicitly flagged to adapt to symbols discovered in a named inspection step (not silent TBDs).
 **Type consistency:** `is_shopify_header` / `map_shopify_header` signatures match between Task 1 (def), Task 2 (import + call), and Task 3 (test). `dialectLabel("shopify")` string is identical in Task 5 def, Task 5 test, and Task 8 E2E assertion (`"Shopify product CSV — mapped"`). `COLUMNS_MD_PATH` defined (Task 6 Step 2) before use (Task 6 Step 3).
 **Deferred decisions (logged to transcript):**
 - `Variant Grams` → `Variant Weight` value with unit forced to `g`; Shopify's own `Variant Weight Unit` display column is *not imported* (warned). Lossless in mass (grams is exact); chosen over carrying a possibly-inconsistent unit. Revisit if merchants need kg/lb display fidelity.
 - DOC-2 served as raw Markdown (`text/markdown`), mirroring how DOC-3 `sample.csv` is served — not a styled HTML page. Satisfies "app-served, source in framework repo"; styled rendering is a future enhancement.
 - Ambiguous header (only shared columns) defaults to **canonical** rather than a distinct `unknown_dialect` state — shared columns map identically so it never misparses (§7.4 intent); avoids a third dialect state the model doesn't carry.
@@ -0,0 +1,2 @@
 Handle,Title,Body (HTML),Vendor,Type,Tags,Published,Status,Variant SKU,Variant Grams,Variant Inventory Qty,Variant Price,Variant Compare At Price,Gift Card,SEO Title,Cost per item
 shopify-mug,Shopify Mug,<p>Imported from Shopify.</p>,Acme,Drinkware,"mugs",TRUE,active,SM-001,300,25,14.00,20.00,FALSE,Shopify Mug | Acme,7.00
@@ -0,0 +1,35 @@
 // DoD scenario e2e_import_shopify_dialect (SD-0002 §6.8, SLICE-8): a Shopify
 // product CSV imports directly (PUC-6). Upload an unmodified-shape Shopify export;
 // the preview recognizes the dialect ("Shopify product CSV — mapped"), lists the
 // columns with no canonical home as not-imported, and the import confirms and
 // completes — the run report card carrying the same dialect label.
 import { expect, test } from "@playwright/test";
 import { gotoProducts, signUpWithStorefront, uploadFixture } from "../helpers";
 test("e2e_import_shopify_dialect", async ({ page }) => {
  await signUpWithStorefront(page);
  await gotoProducts(page);
  await uploadFixture(page, "shopify-export.csv");
  // Preview (§5.4): the file name, the recognized dialect, and the not-imported band.
  await expect(
    page.getByRole("heading", { name: "Import preview — shopify-export.csv" }),
  ).toBeVisible();
  await expect(page.getByText("Shopify product CSV — mapped")).toBeVisible();
  // The not-imported band lists Shopify columns with no canonical home. Assert a
  // column that never appears in canonical diff detail, so the match is unambiguous.
  await expect(page.getByText("Columns not imported")).toBeVisible();
  await expect(page.getByText("Variant Compare At Price")).toBeVisible();
  await expect(page.getByRole("button", { name: "1 to add" })).toBeVisible();
  await expect(page.getByRole("button", { name: "0 errors" })).toBeVisible();
  // Consent gate (PUC-3): confirm the import.
  await page.getByRole("button", { name: "Import 1 products" }).click();
  // Run detail (§5.5): report card carries the same dialect label and completes.
  await expect(page.getByRole("heading", { level: 1, name: "shopify-export.csv" })).toBeVisible();
  await expect(page.getByText("Shopify product CSV — mapped")).toBeVisible();
  await expect(page.getByText("1 added · 0 updated · 0 rows in error")).toBeVisible();
  await expect(page.getByText("Complete", { exact: true })).toBeVisible();
 });
@@ -1,12 +1,12 @@
 {
  "name": "wiggleverse-ecomm-frontend",
-  "version": "0.7.0",
+  "version": "0.8.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "wiggleverse-ecomm-frontend",
-      "version": "0.7.0",
+      "version": "0.8.0",
      "dependencies": {
        "react": "^18.3.1",
        "react-dom": "^18.3.1"
@@ -1,7 +1,7 @@
 {
  "name": "wiggleverse-ecomm-frontend",
  "private": true,
-  "version": "0.7.0",
+  "version": "0.8.0",
  "type": "module",
  "scripts": {
    "dev": "vite",
@@ -0,0 +1,10 @@
 import { describe, expect, it } from "vitest";
 import { dialectLabel } from "./productsApi";
 describe("dialectLabel", () => {
  it("labels canonical", () => expect(dialectLabel("canonical")).toBe("Canonical format"));
  it("labels shopify as mapped (PUC-6)", () =>
    expect(dialectLabel("shopify")).toBe("Shopify product CSV — mapped"));
  it("passes through an unknown dialect verbatim", () =>
    expect(dialectLabel("weird")).toBe("weird"));
 });
@@ -50,7 +50,9 @@ export type Result<T> = { ok: true; value: T } | { ok: false; error: ApiError; s
 // One label rule for CSV dialects, shared by Products history / preview / run detail.
 export function dialectLabel(d: string): string {
-  return d === "canonical" ? "Canonical format" : d;
+  if (d === "canonical") return "Canonical format";
  if (d === "shopify") return "Shopify product CSV — mapped";
  return d;
 }
 export type ExportStatus = "all" | "active" | "draft" | "archived";
@@ -50,9 +50,13 @@ export default function ImportUpload() {
        <span className="note">CSV, up to 5,000 rows</span>
      </label>
      <p className="note">
-        Works with the canonical format.{" "}
+        Works with the canonical format or a Shopify product CSV.{" "}
        <a href="/api/products/sample.csv" download>
          Download sample CSV
        </a>{" "}
        ·{" "}
        <a href="/api/products/columns.md" target="_blank" rel="noopener">
          Column reference
        </a>
      </p>
    </div>
@@ -113,6 +113,10 @@ export default function ProductsPage() {
          <p className="note">
            <a href="/api/products/sample.csv" download>
              Download sample CSV
            </a>{" "}
            ·{" "}
            <a href="/api/products/columns.md" target="_blank" rel="noopener">
              Column reference
            </a>
          </p>
        </div>
		`@@ -0,0 +1,2 @@`
							`Handle,Title,Body (HTML),Vendor,Type,Tags,Published,Status,Variant SKU,Variant Grams,Variant Inventory Qty,Variant Price,Variant Compare At Price,Gift Card,SEO Title,Cost per item`
							`shopify-mug,Shopify Mug,<p>Imported from Shopify.</p>,Acme,Drinkware,"mugs",TRUE,active,SM-001,300,25,14.00,20.00,FALSE,Shopify Mug \| Acme,7.00`