feat(products): /api/products/* BFF endpoints + sample.csv (DOC-3)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

backend/app/main.py

@@ -4,7 +4,8 @@ SLICE-1 mounted /healthz; SLICE-2 adds the /api/auth/* identity endpoints (§6.4
 translates HTTP <-> domain calls and owns no business logic (INV-6): every rule lives in
 the accounts domain. create_app() opens the pool, self-migrates (INV-1, INV-7), and builds
 the configured mailer (INV-8) at startup. SLICE-3 adds POST /api/storefronts and feeds the
-_storefront_for seam from the storefronts domain.
+_storefront_for seam from the storefronts domain. SLICE-5 adds the /api/products/* import
+spine (SD-0002 §6.4): each endpoint is a gate + one products-domain call + error mapping.
 """
 from __future__ import annotations
 
@@ -15,12 +16,12 @@ from pathlib import Path
 from typing import Any
 
 import psycopg
-from fastapi import Depends, FastAPI, Response
-from fastapi.responses import JSONResponse
+from fastapi import Depends, FastAPI, File, Query, Response, UploadFile
+from fastapi.responses import JSONResponse, PlainTextResponse
 from fastapi.staticfiles import StaticFiles
 from pydantic import BaseModel
 
-from app.domains import accounts, storefronts
+from app.domains import accounts, products, storefronts
 from app.platform import config, db
 from app.platform import mailer as mailer_mod
 from app.platform.deps import SESSION_COOKIE, get_conn, get_mailer, get_session
@@ -61,6 +62,26 @@ def _storefront_for(conn: psycopg.Connection, account: accounts.Account) -> dict
     return {"id": sf.id, "name": sf.name} if sf else None
 
 
+def _merchant_gate(
+    conn: psycopg.Connection, sess: dict | None
+) -> JSONResponse | tuple[accounts.Account, storefronts.Storefront]:
+    """The shared /api/products/* gate: a signed-in account that has its storefront.
+
+    Returns the (account, storefront) pair, or the ready-to-return error response —
+    401 with no session, 404 before the storefront exists (INV-14: every products
+    call is storefront-scoped, so there is nothing to address yet).
+    """
+    if sess is None:
+        return _error(401, "unauthenticated", "You are not signed in.")
+    account = accounts.get_account(conn, sess["account_id"])
+    if account is None:
+        return _error(401, "unauthenticated", "You are not signed in.")
+    sf = storefronts.storefront_for(conn, account.id)
+    if sf is None:
+        return _error(404, "no_storefront", "Create your storefront first.")
+    return account, sf
+
+
 def _ensure_app_logging() -> None:
     """Surface the app's own `ecomm.*` INFO logs on stderr (idempotent).
 
@@ -208,6 +229,160 @@ def create_app(database_url: str | None = None, static_dir: str | Path | None =
             )
         return JSONResponse(status_code=201, content={"id": sf.id, "name": sf.name})
 
+    @app.post("/api/products/imports")
+    async def import_upload(
+        file: UploadFile = File(...),
+        conn: psycopg.Connection = Depends(get_conn),
+        sess: dict | None = Depends(get_session),
+    ):
+        """Upload a CSV → validated import draft (§6.4; PUC-2, PUC-5/5a on rejection)."""
+        gate = _merchant_gate(conn, sess)
+        if isinstance(gate, JSONResponse):
+            return gate
+        account, sf = gate
+        data = await file.read()
+        if len(data) > products.MAX_FILE_BYTES:
+            return _error(413, "file_too_large", "This file is larger than 10 MB.")
+        try:
+            draft = products.import_validate(conn, sf.id, account.id, file.filename or "upload.csv", data)
+        except products.FileRejected as exc:
+            return _error(400, exc.code, exc.message)
+        return JSONResponse(status_code=201, content=draft)
+
+    @app.get("/api/products/imports/drafts/{draft_id}")
+    def get_import_draft(
+        draft_id: int,
+        conn: psycopg.Connection = Depends(get_conn),
+        sess: dict | None = Depends(get_session),
+    ):
+        """One draft's preview payload — summary, never the file bytes (§6.4; PUC-3)."""
+        gate = _merchant_gate(conn, sess)
+        if isinstance(gate, JSONResponse):
+            return gate
+        _account, sf = gate
+        try:
+            return products.get_draft(conn, sf.id, draft_id)
+        except products.DraftNotFound:
+            return _error(404, "not_found", "No such import preview.")
+        except products.DraftExpired:
+            return _error(410, "draft_expired", "This preview expired — upload the file again.")
+
+    @app.get("/api/products/imports/drafts/{draft_id}/records")
+    def get_import_draft_records(
+        draft_id: int,
+        kind: str | None = Query(default=None, pattern="^(add|update|unchanged|error)$"),
+        limit: int = Query(default=100, ge=1, le=500),
+        offset: int = Query(default=0, ge=0),
+        conn: psycopg.Connection = Depends(get_conn),
+        sess: dict | None = Depends(get_session),
+    ):
+        """The draft's per-product preview records, paged + kind-filtered (§6.4; PUC-3)."""
+        gate = _merchant_gate(conn, sess)
+        if isinstance(gate, JSONResponse):
+            return gate
+        _account, sf = gate
+        try:
+            records = products.get_draft_records(conn, sf.id, draft_id, kind, limit, offset)
+        except products.DraftNotFound:
+            return _error(404, "not_found", "No such import preview.")
+        except products.DraftExpired:
+            return _error(410, "draft_expired", "This preview expired — upload the file again.")
+        return {"records": records}
+
+    @app.post("/api/products/imports/drafts/{draft_id}/confirm")
+    def confirm_import_draft(
+        draft_id: int,
+        conn: psycopg.Connection = Depends(get_conn),
+        sess: dict | None = Depends(get_session),
+    ):
+        """Apply the previewed diff as one import run (§6.4; PUC-4, INV-10/11)."""
+        gate = _merchant_gate(conn, sess)
+        if isinstance(gate, JSONResponse):
+            return gate
+        account, sf = gate
+        try:
+            run_id = products.confirm_draft(conn, sf.id, account.id, draft_id)
+        except products.DraftNotFound:
+            return _error(404, "not_found", "No such import preview.")
+        except products.DraftExpired:
+            return _error(410, "draft_expired", "This preview expired — upload the file again.")
+        except products.PreviewStale:
+            return _error(
+                409, "preview_stale",
+                "Your catalog changed since this preview — upload the file again.",
+            )
+        except products.NothingToApply:
+            return _error(
+                409, "nothing_to_apply",
+                "Nothing to change — your catalog already matches this file.",
+            )
+        return JSONResponse(status_code=201, content={"run_id": run_id})
+
+    @app.delete("/api/products/imports/drafts/{draft_id}")
+    def discard_import_draft(
+        draft_id: int,
+        conn: psycopg.Connection = Depends(get_conn),
+        sess: dict | None = Depends(get_session),
+    ):
+        """Discard the draft, no trace kept; idempotent (§6.4; PUC-3a)."""
+        gate = _merchant_gate(conn, sess)
+        if isinstance(gate, JSONResponse):
+            return gate
+        _account, sf = gate
+        products.discard_draft(conn, sf.id, draft_id)
+        return Response(status_code=204)
+
+    @app.get("/api/products/imports/runs")
+    def list_import_runs(
+        limit: int = Query(default=50, ge=1, le=200),
+        offset: int = Query(default=0, ge=0),
+        conn: psycopg.Connection = Depends(get_conn),
+        sess: dict | None = Depends(get_session),
+    ):
+        """The storefront's import history, newest first (§6.4; PUC-8)."""
+        gate = _merchant_gate(conn, sess)
+        if isinstance(gate, JSONResponse):
+            return gate
+        _account, sf = gate
+        return {"runs": products.list_runs(conn, sf.id, limit, offset)}
+
+    @app.get("/api/products/imports/runs/{run_id}")
+    def get_import_run(
+        run_id: int,
+        conn: psycopg.Connection = Depends(get_conn),
+        sess: dict | None = Depends(get_session),
+    ):
+        """One run's detail payload, errors included (§6.4; PUC-8)."""
+        gate = _merchant_gate(conn, sess)
+        if isinstance(gate, JSONResponse):
+            return gate
+        _account, sf = gate
+        try:
+            return products.get_run(conn, sf.id, run_id)
+        except products.RunNotFound:
+            return _error(404, "not_found", "No such import run.")
+
+    @app.get("/api/products/summary")
+    def products_summary(
+        conn: psycopg.Connection = Depends(get_conn),
+        sess: dict | None = Depends(get_session),
+    ):
+        """The products dashboard counts (§6.4)."""
+        gate = _merchant_gate(conn, sess)
+        if isinstance(gate, JSONResponse):
+            return gate
+        _account, sf = gate
+        return products.summary(conn, sf.id)
+
+    @app.get("/api/products/sample.csv")
+    def products_sample_csv():
+        """The DOC-3 worked-example CSV. Documentation, so no auth gate (§6.4)."""
+        return PlainTextResponse(
+            products.SAMPLE_CSV_PATH.read_text(),
+            media_type="text/csv",
+            headers={"content-disposition": 'attachment; filename="ecomm-products-sample.csv"'},
+        )
+
     # 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.