diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 0000000..a2f4b3e
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1,22 @@
+# Line endings, pinned so they do not depend on each developer's Git config.
+#
+# Git for Windows ships core.autocrlf=true in its system gitconfig, which
+# stores LF but checks out CRLF - the source of the "LF will be replaced by
+# CRLF" warnings on `git add`. Declaring the policy here overrides that for
+# everyone, so Windows, Linux and the Docker build all agree.
+#
+# The repository is already entirely LF (`git ls-files --eol` shows i/lf
+# across the board), so eol=lf pins the working tree to what the index
+# already holds and rewrites no committed content.
+* text=auto eol=lf
+
+# Binaries must never be EOL-converted - a substituted byte corrupts them.
+# Git already auto-detects these; saying so explicitly means a future edit
+# to the wildcard above cannot silently start mangling them.
+*.joblib binary
+*.db     binary
+
+# Windows-only scripts genuinely need CRLF. None are tracked in this repo
+# today (start_app.bat lives above it), but the rule belongs with the policy.
+*.bat text eol=crlf
+*.ps1 text eol=crlf
diff --git a/app/api/routers/brands.py b/app/api/routers/brands.py
index 895dcf2..fddeb55 100644
--- a/app/api/routers/brands.py
+++ b/app/api/routers/brands.py
@@ -1,12 +1,22 @@
 from __future__ import annotations
 
+import re
 from typing import Optional
 
 from fastapi import APIRouter, HTTPException, Query
 
-from app.api.schemas import AllProductsOut, BrandsOut, CategoriesOut, ProductListOut, ProductOut
+from app.api.schemas import (
+    AllProductsOut,
+    BrandCardOut,
+    BrandCardsOut,
+    BrandsOut,
+    CategoriesOut,
+    ProductListOut,
+    ProductOut,
+)
 from app.services.s3_service import s3_service
 from app.services.vector_store import (
+    get_brand_overview,
     list_available_brands,
     list_categories_for_brand,
     get_products_by_brand,
@@ -106,6 +116,53 @@ def get_brands() -> BrandsOut:
     return BrandsOut(brands=list_available_brands())
 
 
+def _initials(name: str) -> str:
+    """Monogram for the card's image fallback - there are no logo assets."""
+    words = [w for w in re.split(r"[^A-Za-z0-9]+", name) if w]
+    if not words:
+        return "?"
+    if len(words) == 1:
+        return words[0][:2].upper()
+    return (words[0][0] + words[1][0]).upper()
+
+
+# Declared before /brands/{brand}/... so "overview" is never read as a brand
+# name. The path-segment counts differ, so this is belt-and-braces.
+@router.get("/brands/overview", response_model=BrandCardsOut)
+def get_brand_cards(
+    refresh: bool = Query(False, description="Bypass the short-lived overview cache"),
+) -> BrandCardsOut:
+    """Per-brand summaries for the home page card grid.
+
+    Additive: GET /brands keeps returning a plain list of names, which the
+    sidebar and the admin/user pages rely on.
+    """
+    rows = get_brand_overview(force_refresh=refresh)
+
+    cards = []
+    for row in rows:
+        name = row["display_name"]
+        image_url = _clean_url(row.get("sample_image_url"))
+        if not image_url and s3_service.enabled and row.get("sample_image_id"):
+            image_url = s3_service.get_product_image_url(name, row["sample_image_id"])
+
+        cards.append(BrandCardOut(
+            name=name,
+            slug=row["suffix"],
+            product_count=row["product_count"],
+            category_count=row["category_count"],
+            categories=list(row.get("categories") or []),
+            image_url=image_url,
+            initials=_initials(name),
+        ))
+
+    return BrandCardsOut(
+        total_brands=len(cards),
+        total_products=sum(c.product_count for c in cards),
+        brands=cards,
+    )
+
+
 @router.get("/brands/{brand}/categories", response_model=CategoriesOut)
 def get_brand_categories(brand: str) -> CategoriesOut:
     return CategoriesOut(brand=brand, categories=list_categories_for_brand(brand))
diff --git a/app/api/routers/system.py b/app/api/routers/system.py
index 5b5a1bc..8df2187 100644
--- a/app/api/routers/system.py
+++ b/app/api/routers/system.py
@@ -48,6 +48,26 @@ def _run_background_auto_seed():
         logger.error("Background Auto-Init error: %s", e)
 
 
+def _run_background_brand_sync() -> None:
+    """Reconcile brand tables against data/seed_catalogs/ in both directions.
+
+    Complements the auto-seed above rather than replacing it: that one only
+    fires against a completely empty database, so without this a brand table
+    created after first boot never gets a seed file, and a seed file added
+    after first boot is never loaded.
+    """
+    try:
+        from app.services.brand_sync import reconcile_brand_catalogs
+        summary = reconcile_brand_catalogs()
+        logger.info("🔁 Brand catalog reconcile: %s", summary)
+    except Exception as e:
+        logger.error("Brand catalog reconcile error: %s", e)
+
+
+class BrandSyncRequest(BaseModel):
+    dry_run: bool = False
+
+
 @router.get("/system/status", response_model=SystemStatusOut)
 def get_system_status() -> SystemStatusOut:
     """Return unified status of database, vector store, stores, and frontend build."""
@@ -89,3 +109,23 @@ def initialize_system(background_tasks: BackgroundTasks) -> Dict[str, Any]:
         "status": "started",
         "message": "Background initialization triggered. Check /api/system/status for progress.",
     }
+
+
+@router.post("/system/brand-sync", dependencies=[Depends(require_admin)])
+def sync_brand_catalogs(payload: BrandSyncRequest, background_tasks: BackgroundTasks) -> Dict[str, Any]:
+    """Reconcile brand tables with their seed catalog files.
+
+    `dry_run` answers inline - it is a handful of count queries and writes
+    nothing, so it is safe to poke at. A real run is backgrounded because
+    exporting a large brand serialises thousands of 384-float embeddings.
+    """
+    from app.services.brand_sync import reconcile_brand_catalogs
+
+    if payload.dry_run:
+        return {"status": "ok", "summary": reconcile_brand_catalogs(dry_run=True)}
+
+    background_tasks.add_task(_run_background_brand_sync)
+    return {
+        "status": "started",
+        "message": "Brand catalog reconcile triggered. Check /api/system/status for progress.",
+    }
diff --git a/app/api/routers/user_products.py b/app/api/routers/user_products.py
index fbf52f7..3b19017 100644
--- a/app/api/routers/user_products.py
+++ b/app/api/routers/user_products.py
@@ -1,8 +1,6 @@
 import io
-import json
 import logging
 import re
-from pathlib import Path
 from typing import Any, Dict, List, Optional
 import pandas as pd
 from pydantic import BaseModel, Field
@@ -16,14 +14,13 @@ from app.services.vector_store import (
     _sanitize_name,
     get_products_by_brand,
 )
+from app.services.brand_sync import upsert_products_into_catalog_file
 from app.services.embeddings_service import embed_texts
 from app.services.s3_service import s3_service
 
 logger = logging.getLogger(__name__)
 router = APIRouter(prefix="/user/products", tags=["user_products"])
 
-SEED_DIR = Path(__file__).resolve().parents[3] / "data" / "seed_catalogs"
-
 
 class AddProductRequest(BaseModel):
     brand: str = Field(..., description="Brand name, e.g. Lion Dates")
@@ -174,50 +171,14 @@ def _enrich_and_save_product(req: AddProductRequest) -> Dict[str, Any]:
 
 
 def _update_json_catalog_file(brand: str, product_dict: Dict[str, Any]) -> None:
-    SEED_DIR.mkdir(parents=True, exist_ok=True)
+    """Append/update one product in the brand's seed catalog.
 
-    # Determine seed file name (e.g. brand_catalog_lion_dates.json)
-    brand_slug = _sanitize_name(resolve_parent_brand(brand))
-    file_path = SEED_DIR / f"brand_catalog_{brand_slug}.json"
-
-    # Strip embedding before saving to JSON file for clean JSON size
-    clean_dict = {k: v for k, v in product_dict.items() if k != "embedding"}
-
-    if file_path.exists():
-        try:
-            data = json.loads(file_path.read_text(encoding="utf-8-sig"))
-        except Exception as e:
-            logger.warning("Could not read existing catalog JSON %s: %s", file_path.name, e)
-            data = {"brand": brand, "products": []}
-    else:
-        data = {
-            "brand": brand.lower(),
-            "search_query": f"{brand} products catalog",
-            "generation_timestamp": str(Path(__file__).resolve()),
-            "total_products": 0,
-            "total_images": 0,
-            "products": [],
-        }
-
-    products_list = data.get("products", [])
-
-    # Replace existing or append new product
-    updated = False
-    for i, p in enumerate(products_list):
-        if p.get("image_id") == clean_dict["image_id"] or p.get("product_name") == clean_dict["product_name"]:
-            products_list[i] = clean_dict
-            updated = True
-            break
-
-    if not updated:
-        products_list.append(clean_dict)
-
-    data["products"] = products_list
-    data["total_products"] = len(products_list)
-    data["total_images"] = sum(len(p.get("image_urls") or []) for p in products_list)
-
-    file_path.write_text(json.dumps(data, indent=2, ensure_ascii=False), encoding="utf-8")
-    logger.info("✅ Updated JSON seed file '%s' (total products: %d)", file_path.name, data["total_products"])
+    Delegates to brand_sync so this shares the file-resolution rules with the
+    startup reconcile. That also fixes a mis-targeting bug this used to have:
+    picking the file by sanitised slug wrote P&G products to a new
+    brand_catalog_p_g.json instead of the real brand_catalog_p_and_g.json.
+    """
+    upsert_products_into_catalog_file(brand, [product_dict])
 
 
 @router.post("/add", status_code=201, dependencies=[Depends(require_permission("add_product"))])
diff --git a/app/api/schemas.py b/app/api/schemas.py
index 8cf0365..1395229 100644
--- a/app/api/schemas.py
+++ b/app/api/schemas.py
@@ -79,6 +79,27 @@ class BrandsOut(BaseModel):
     brands: List[str]
 
 
+class BrandCardOut(BaseModel):
+    """A brand as shown on the home page card grid.
+
+    `name` is the same string GET /api/brands returns, so the frontend can
+    pass it straight back to /api/brands/{brand}/products.
+    """
+    name: str
+    slug: str
+    product_count: int
+    category_count: int
+    categories: List[str] = Field(default_factory=list)
+    image_url: Optional[str] = None
+    initials: str
+
+
+class BrandCardsOut(BaseModel):
+    total_brands: int
+    total_products: int
+    brands: List[BrandCardOut]
+
+
 class CategoriesOut(BaseModel):
     brand: str
     categories: List[str]
diff --git a/app/core/ingestion.py b/app/core/ingestion.py
index e7bff4c..ceb1a4f 100644
--- a/app/core/ingestion.py
+++ b/app/core/ingestion.py
@@ -32,6 +32,20 @@ async def ingest_brand(brand: str, max_products: int = 50) -> Dict[str, Any]:
     catalog = await catalog_engine.generate_catalog(brand=brand, max_products=max_products)
     duration = time.time() - start
 
+    # Mirror the freshly ingested rows into data/seed_catalogs/ so a brand that
+    # arrived through the pipeline is reproducible from disk like the bundled
+    # ones. Reading back from pgvector rather than reusing catalog["products"]
+    # keeps the file honest about what was actually stored.
+    #
+    # Placed here rather than in the API router because this function is also
+    # the CLI's entry point (cli/ingest_brand.py), and a failure to write the
+    # file must not turn a successful ingest into a failed job.
+    try:
+        from app.services.brand_sync import export_brand_to_seed_file
+        export_brand_to_seed_file(brand)
+    except Exception:  # noqa: BLE001 - DB rows are already committed
+        logger.warning("Seed-catalog export failed for %s (DB rows intact)", brand, exc_info=True)
+
     summary = {
         "brand": brand,
         "total_products": catalog.get("total_products", 0),
diff --git a/app/main.py b/app/main.py
index f4c500c..e764438 100644
--- a/app/main.py
+++ b/app/main.py
@@ -47,8 +47,13 @@ async def lifespan(_app: FastAPI):
         try:
             ensure_store_intelligence_schema()
             ensure_nutrition_schema()
-            from app.api.routers.system import _run_background_auto_seed
+            from app.api.routers.system import _run_background_auto_seed, _run_background_brand_sync
             _run_background_auto_seed()
+            # Runs after the auto-seed so a cold boot has already loaded the
+            # bundled catalogs and this finds nothing to do. On a warm boot the
+            # auto-seed no-ops and this is what picks up a brand table or seed
+            # file that appeared since last time.
+            _run_background_brand_sync()
         except Exception as e:
             logger.warning("Startup background init warning: %s", e)
 
diff --git a/app/services/brand_registry.py b/app/services/brand_registry.py
index 2afaf77..4e16595 100644
--- a/app/services/brand_registry.py
+++ b/app/services/brand_registry.py
@@ -1,3 +1,6 @@
+import re
+from functools import lru_cache
+
 BRAND_ALIASES = {
     # Cadbury family
     "cadbury gems": "cadbury",
@@ -253,6 +256,21 @@ BRAND_ALIASES = {
 DEFAULT_ALIASES = BRAND_ALIASES
 
 
+def _contains_word(haystack: str, needle: str) -> bool:
+    """True when `needle` occurs in `haystack` as a whole word.
+
+    Plain `in` would treat any fragment as a match, so a short brand name
+    could be swallowed by an unrelated alias that merely contains those
+    letters - e.g. "sun" inside "hul sunsilk". Anchoring both ends on a
+    word boundary keeps the genuine multi-word hits ("tata" inside
+    "hul tata tea") while dropping the fragment ones.
+    """
+    if not needle:
+        return False
+    return re.search(r"(?<!\w)" + re.escape(needle) + r"(?!\w)", haystack) is not None
+
+
+@lru_cache(maxsize=1024)
 def resolve_parent_brand(brand: str) -> str:
     """Return the parent (canonical) brand for storage purposes.
 
@@ -260,15 +278,19 @@ def resolve_parent_brand(brand: str) -> str:
     returns the parent brand name so that sub-brands share the same
     database table, S3 folder, and JSON file as their parent.
 
-    Falls back to fuzzy substring matching, then returns the input
-    unchanged if no alias is known.
+    Falls back to whole-word matching in either direction, then returns
+    the input unchanged if no alias is known.
+
+    Cached because `_table_name()` in vector_store calls this on every
+    query and the fallback loop scans all ~230 aliases. BRAND_ALIASES is
+    a module constant that is never mutated, so the result is stable.
     """
     key = brand.lower().strip()
     direct = BRAND_ALIASES.get(key)
     if direct:
         return direct
     for alias, parent in BRAND_ALIASES.items():
-        if alias in key or key in alias:
+        if _contains_word(key, alias) or _contains_word(alias, key):
             return parent
     return brand
 
diff --git a/app/services/brand_sync.py b/app/services/brand_sync.py
new file mode 100644
index 0000000..3c3e84a
--- /dev/null
+++ b/app/services/brand_sync.py
@@ -0,0 +1,433 @@
+"""
+Keeps the `brand_*` Postgres tables and `data/seed_catalogs/*.json` in step.
+
+A brand can enter the system from either side: `POST /api/user/products/add`
+and `POST /api/catalog/generate` write rows, while a catalog file may be
+dropped in by hand or shipped in the image. Neither side used to produce the
+other, so a brand ingested at runtime had no seed file, and a seed file added
+after first boot was never loaded (the startup auto-seed only runs against a
+completely empty database).
+
+This module is the single place that knows the correspondence between the two,
+and `reconcile_brand_catalogs()` repairs it in both directions.
+
+The correspondence is *not* the filename. `brand_catalog_p_and_g.json` holds
+`"brand": "p&g"`, which sanitises to table `brand_p_g`; `brand_catalog_tata.json`
+resolves through BRAND_ALIASES into `brand_hindustan_unilever`. Everything here
+therefore indexes files by their `brand` field, exactly as
+`scripts/seed_sample_data.py` does. Keying on filenames instead would split
+P&G across two files and let Tata clobber Hindustan Unilever.
+"""
+from __future__ import annotations
+
+import json
+import logging
+import os
+from collections import defaultdict
+from decimal import Decimal
+from pathlib import Path
+from typing import Any, Dict, List, Optional
+
+from app.services.brand_registry import resolve_parent_brand
+from app.services.vector_store import (
+    _connect,
+    _list_brand_table_suffixes,
+    _sanitize_name,
+    display_name_for_suffix,
+    ensure_brand_schema,
+    get_products_by_brand,
+    invalidate_brand_overview_cache,
+    upsert_brand_products,
+)
+
+logger = logging.getLogger(__name__)
+
+# app/services/brand_sync.py -> parents[2] is backend/
+SEED_DIR = Path(__file__).resolve().parents[2] / "data" / "seed_catalogs"
+
+# The column list written by upsert_brand_products, minus `embedding` (handled
+# separately because it is huge and optional). Keeping these in sync is what
+# makes an exported file round-trip back through the seeder without losing
+# hsn/price/barcode/sku data - the failing mode of scripts/export_seed_data.py.
+EXPORT_COLUMNS = (
+    "product_name", "title", "description", "category", "image_id",
+    "image_url", "image_urls", "price_range", "size_variants", "providers",
+    "fssai_license", "product_sku", "sku_source", "hsn_code",
+    "final_selling_price", "selling_price", "barcode", "barcode_type",
+    "highlights", "nutrients", "search_query",
+)
+
+
+def brand_slug(brand: str) -> str:
+    """The table suffix a brand name resolves to (e.g. 'ITC' -> 'itc')."""
+    return _sanitize_name(resolve_parent_brand(brand))
+
+
+def _read_catalog(path: Path) -> Optional[Dict[str, Any]]:
+    """Parse a seed catalog, returning None for anything that isn't one.
+
+    Files without a brand or products (notably `hsn_gst_master.json`) are not
+    catalogs, and a corrupt file must not take down a startup reconcile.
+    """
+    try:
+        data = json.loads(path.read_text(encoding="utf-8-sig"))
+    except Exception as e:  # noqa: BLE001 - one bad file cannot break the sweep
+        logger.warning("Could not read seed catalog %s: %s", path.name, e)
+        return None
+    if not isinstance(data, dict):
+        return None
+    products = data.get("products")
+    if not isinstance(products, list) or not products:
+        return None
+    brand = data.get("brand") or (products[0].get("brand_name") if isinstance(products[0], dict) else None)
+    if not brand:
+        return None
+    data["brand"] = brand
+    return data
+
+
+def index_seed_files(seed_dir: Path = SEED_DIR) -> Dict[str, List[Path]]:
+    """Map each brand table suffix to the seed files that feed it.
+
+    More than one file can feed a suffix - tata.json and hindustan_unilever.json
+    both land in brand_hindustan_unilever - which is why the value is a list.
+    """
+    index: Dict[str, List[Path]] = defaultdict(list)
+    if not seed_dir.exists():
+        return {}
+    for path in sorted(seed_dir.glob("*.json")):
+        data = _read_catalog(path)
+        if data is None:
+            continue
+        index[brand_slug(data["brand"])].append(path)
+    return dict(index)
+
+
+# Resolving a brand to its file means parsing every catalog, and /batch-add
+# calls that once per product. The mapping only changes when a file is created
+# or removed, so it is cached and invalidated explicitly on write.
+_TARGET_CACHE: Dict[str, Path] = {}
+
+
+def invalidate_seed_index_cache() -> None:
+    _TARGET_CACHE.clear()
+
+
+def canonical_seed_file(brand: str, index: Optional[Dict[str, List[Path]]] = None) -> Path:
+    """The file to write for `brand`.
+
+    Prefers a file whose own brand field sanitises to the same slug, so P&G
+    products append to brand_catalog_p_and_g.json rather than creating an
+    orphan brand_catalog_p_g.json, and Hindustan Unilever products never get
+    written into brand_catalog_tata.json.
+    """
+    slug = brand_slug(brand)
+    if index is None:
+        cached = _TARGET_CACHE.get(slug)
+        if cached is not None:
+            return cached
+        index = index_seed_files()
+
+    resolved = SEED_DIR / f"brand_catalog_{slug}.json"
+    candidates = index.get(slug, [])
+    for path in candidates:
+        data = _read_catalog(path)
+        if data and _sanitize_name(data["brand"]) == slug:
+            resolved = path
+            break
+    else:
+        if candidates:
+            resolved = candidates[0]
+
+    _TARGET_CACHE[slug] = resolved
+    return resolved
+
+
+def upsert_products_into_catalog_file(brand: str, products: List[Dict[str, Any]]) -> Optional[Path]:
+    """Merge `products` into the brand's seed catalog, creating it if needed.
+
+    Products are matched on image_id or product_name, so re-adding an existing
+    product updates it in place instead of duplicating. Embeddings are stripped
+    (they are ~384 floats each and the file is meant to stay readable), and the
+    write is atomic so a crash cannot leave a half-written catalog that then
+    fails to parse on the next boot.
+    """
+    if not products:
+        return None
+
+    SEED_DIR.mkdir(parents=True, exist_ok=True)
+    file_path = canonical_seed_file(brand)
+
+    if file_path.exists():
+        try:
+            data = json.loads(file_path.read_text(encoding="utf-8-sig"))
+        except Exception as e:  # noqa: BLE001
+            logger.warning("Could not read existing catalog JSON %s: %s", file_path.name, e)
+            data = {"brand": brand, "products": []}
+    else:
+        data = {
+            "brand": brand.lower(),
+            "search_query": f"{brand} products catalog",
+            "generation_timestamp": str(Path(__file__).resolve()),
+            "total_products": 0,
+            "total_images": 0,
+            "products": [],
+        }
+
+    products_list = data.get("products") or []
+    by_image_id = {
+        p.get("image_id"): i for i, p in enumerate(products_list) if p.get("image_id")
+    }
+    by_name = {
+        p.get("product_name"): i for i, p in enumerate(products_list) if p.get("product_name")
+    }
+
+    for product in products:
+        clean = {k: v for k, v in product.items() if k != "embedding"}
+        idx = by_image_id.get(clean.get("image_id"))
+        if idx is None:
+            idx = by_name.get(clean.get("product_name"))
+        if idx is None:
+            products_list.append(clean)
+            if clean.get("image_id"):
+                by_image_id[clean["image_id"]] = len(products_list) - 1
+            if clean.get("product_name"):
+                by_name[clean["product_name"]] = len(products_list) - 1
+        else:
+            products_list[idx] = clean
+
+    data["products"] = products_list
+    data["total_products"] = len(products_list)
+    data["total_images"] = sum(len(p.get("image_urls") or []) for p in products_list)
+
+    payload = json.dumps(data, indent=2, ensure_ascii=False)
+    tmp_path = file_path.with_suffix(".json.tmp")
+    tmp_path.write_text(payload, encoding="utf-8")
+    os.replace(tmp_path, file_path)
+
+    logger.info("✅ Updated JSON seed file '%s' (total products: %d)",
+                file_path.name, data["total_products"])
+    return file_path
+
+
+def _jsonable(value: Any) -> Any:
+    """Coerce a psycopg row value into something json.dumps accepts."""
+    if isinstance(value, Decimal):
+        return float(value)
+    if isinstance(value, (list, tuple)):
+        return [_jsonable(v) for v in value]
+    return value
+
+
+def export_brand_to_seed_file(brand: str, include_embeddings: bool = True) -> Optional[Path]:
+    """Write a brand's database rows out to its seed catalog, field-complete.
+
+    Deliberately not scripts/export_seed_data.py, whose _read_products emits
+    only ~10 keys - running that would silently strip hsn_code, prices,
+    barcodes, SKUs and FSSAI numbers out of the existing catalogs.
+
+    Embeddings are carried through when present because that is what lets
+    seed_sample_data.py re-seed without invoking the embedding model.
+    """
+    rows = get_products_by_brand(brand)
+    if not rows:
+        logger.info("Nothing to export for brand '%s' (no rows)", brand)
+        return None
+
+    display = display_name_for_suffix(brand_slug(brand))
+    products: List[Dict[str, Any]] = []
+    for row in rows:
+        product: Dict[str, Any] = {"brand": display, "brand_name": display}
+        for col in EXPORT_COLUMNS:
+            if col in row:
+                product[col] = _jsonable(row[col])
+        if include_embeddings and row.get("embedding") is not None:
+            try:
+                product["embedding"] = [float(x) for x in row["embedding"]]
+            except (TypeError, ValueError):
+                pass
+        products.append(product)
+
+    path = upsert_products_into_catalog_file(display, products)
+    if path:
+        logger.info("📤 Exported %d product(s) for '%s' -> %s", len(products), display, path.name)
+    return path
+
+
+def load_seed_catalogs(seed_dir: Path = SEED_DIR,
+                       only: Optional[List[str]] = None) -> Dict[str, List[Dict[str, Any]]]:
+    """Read seed catalogs and group their products by resolved parent brand.
+
+    Grouping matters: several files can feed one table, and the seeder's
+    stale-row cleanup deletes anything not in the batch it is given. Merging
+    first is what stops tata.json and hindustan_unilever.json erasing each
+    other.
+    """
+    if not seed_dir.exists():
+        logger.error("Seed directory not found: %s", seed_dir)
+        return {}
+
+    files = sorted(seed_dir.glob("*.json"))
+    if only:
+        wanted = [w.lower() for w in only]
+        files = [f for f in files if any(w in f.name.lower() for w in wanted)]
+
+    brand_products: Dict[str, List[Dict[str, Any]]] = defaultdict(list)
+    for path in files:
+        data = _read_catalog(path)
+        if data is None:
+            logger.warning("Skipping %s - no brand/products found", path.name)
+            continue
+        resolved = resolve_parent_brand(data["brand"])
+        brand_products[resolved].extend(data["products"])
+        logger.info("Read %d products from %s -> resolved brand '%s'",
+                    len(data["products"]), path.name, resolved)
+
+    return dict(brand_products)
+
+
+def seed_brands(brand_products: Dict[str, List[Dict[str, Any]]], cleanup: bool = True) -> int:
+    """Upsert grouped products into their brand tables. Returns the row count."""
+    total = 0
+    for resolved_brand, all_products in brand_products.items():
+        logger.info("Seeding %d product(s) for brand '%s'", len(all_products), resolved_brand)
+        table = ensure_brand_schema(resolved_brand)
+        if not table:
+            logger.error("Could not create/verify table for brand '%s' - is pgvector reachable?",
+                         resolved_brand)
+            continue
+        upsert_brand_products(resolved_brand, all_products, cleanup=cleanup)
+        logger.info("Seeded %d products for brand '%s' (table=%s)",
+                    len(all_products), resolved_brand, table)
+        total += len(all_products)
+    return total
+
+
+def _db_brand_counts() -> Dict[str, int]:
+    """{table suffix: row count} for every brand_* table, on one connection."""
+    conn = _connect()
+    if not conn:
+        return {}
+    counts: Dict[str, int] = {}
+    try:
+        with conn, conn.cursor() as cur:
+            for suffix in sorted(set(_list_brand_table_suffixes(cur))):
+                try:
+                    cur.execute(f"SELECT COUNT(*) FROM brand_{suffix}")
+                    row = cur.fetchone()
+                    counts[suffix] = int(row[0]) if row else 0
+                except Exception as e:  # noqa: BLE001
+                    logger.warning("Could not count brand_%s: %s", suffix, e)
+    except Exception as e:  # noqa: BLE001
+        logger.error("Failed to enumerate brand tables: %s", e)
+    finally:
+        conn.close()
+    return counts
+
+
+def _detect_collisions(seed_dir: Path = SEED_DIR) -> List[Dict[str, Any]]:
+    """Distinct parent brands that sanitise onto one table (e.g. 'P&G' vs 'P G').
+
+    Grouped by *resolved parent*, not by the raw brand field: tata.json and
+    hindustan_unilever.json share a table because BRAND_ALIASES deliberately
+    merges them, which is not a collision. A genuine one is two unrelated
+    parents whose names differ only in characters _sanitize_name strips.
+
+    Reported rather than repaired - renaming a live table is a one-way door,
+    and nothing collides today. This is here so it surfaces the day it does.
+    """
+    by_slug: Dict[str, set] = defaultdict(set)
+    if not seed_dir.exists():
+        return []
+    for path in sorted(seed_dir.glob("*.json")):
+        data = _read_catalog(path)
+        if data is None:
+            continue
+        parent = resolve_parent_brand(data["brand"]).strip().lower()
+        by_slug[_sanitize_name(parent)].add(parent)
+    return [
+        {"slug": slug, "brands": sorted(names)}
+        for slug, names in sorted(by_slug.items()) if len(names) > 1
+    ]
+
+
+def reconcile_brand_catalogs(dry_run: bool = False) -> Dict[str, Any]:
+    """Repair the table <-> seed-file correspondence in both directions.
+
+    Idempotent and non-destructive:
+
+      * A populated table with no seed file gets one exported.
+      * A seed file whose table is empty or absent gets seeded, with
+        cleanup disabled - the table holds nothing this batch could be a
+        partial view of, so there is no stale row to remove and no way to
+        delete data by passing an incomplete set.
+      * A file that already maps to a populated table is left alone. That
+        rule is what stops brand_catalog_tata.json being overwritten with
+        Hindustan Unilever's merged rows.
+    """
+    # Files may have appeared on disk since the last resolve (that is half of
+    # what this function exists to handle), so start from a cold index.
+    invalidate_seed_index_cache()
+
+    db_counts = _db_brand_counts()
+    file_index = index_seed_files()
+    collisions = _detect_collisions()
+
+    to_export = sorted(
+        suffix for suffix, count in db_counts.items()
+        if count > 0 and suffix not in file_index
+    )
+    to_seed = sorted(
+        slug for slug in file_index
+        if db_counts.get(slug, 0) == 0
+    )
+
+    summary: Dict[str, Any] = {
+        "tables": len(db_counts),
+        "files": len(file_index),
+        "exported": [],
+        "seeded": [],
+        "collisions": collisions,
+        "skipped": [],
+        "dry_run": dry_run,
+    }
+
+    if dry_run:
+        summary["exported"] = [display_name_for_suffix(s) for s in to_export]
+        summary["seeded"] = to_seed
+        return summary
+
+    for suffix in to_export:
+        display = display_name_for_suffix(suffix)
+        try:
+            path = export_brand_to_seed_file(display)
+            if path:
+                summary["exported"].append(display)
+        except Exception as e:  # noqa: BLE001 - one brand must not stop the sweep
+            logger.error("Export failed for brand '%s': %s", display, e)
+            summary["skipped"].append({"brand": display, "reason": str(e)})
+
+    for slug in to_seed:
+        paths = file_index.get(slug, [])
+        try:
+            grouped = load_seed_catalogs(only=[p.name for p in paths])
+            if not grouped:
+                continue
+            seed_brands(grouped, cleanup=False)
+            summary["seeded"].append(slug)
+        except Exception as e:  # noqa: BLE001
+            logger.error("Seeding failed for slug '%s': %s", slug, e)
+            summary["skipped"].append({"brand": slug, "reason": str(e)})
+
+    if summary["exported"] or summary["seeded"]:
+        invalidate_brand_overview_cache()
+        try:
+            from app.services.query_intent import invalidate_brand_mention_cache
+            invalidate_brand_mention_cache()
+        except Exception:  # noqa: BLE001
+            pass
+
+    if collisions:
+        logger.warning("Brand slug collisions detected: %s", collisions)
+
+    return summary
diff --git a/app/services/query_intent.py b/app/services/query_intent.py
index 8f091bf..c04733e 100644
--- a/app/services/query_intent.py
+++ b/app/services/query_intent.py
@@ -15,7 +15,8 @@ and free on CPU-only hardware. Two things are extracted:
 from __future__ import annotations
 
 import re
-from typing import Dict, Optional
+import time
+from typing import Any, Dict, Optional
 
 from app.services.category_registry import detect_category_from_text  # noqa: F401 (re-exported)
 
@@ -170,18 +171,70 @@ BRAND_SEARCH_MAP = {
 }
 
 
+BRAND_MENTION_TTL_SECONDS = 300
+
+# Populated lazily by _brand_index(); holds the static tables above merged with
+# whatever brands actually exist in the vector store right now.
+_MENTION_CACHE: Dict[str, Any] = {"at": 0.0, "known": None, "map": None}
+
+
+def invalidate_brand_mention_cache() -> None:
+    """Force the next _brand_index() call to re-read the live brand list.
+
+    Called after a brand is added or the seed catalogs are reconciled, so a
+    newly ingested brand becomes mentionable without waiting out the TTL.
+    """
+    _MENTION_CACHE.update(at=0.0, known=None, map=None)
+
+
+def _brand_index() -> tuple[list[str], Dict[str, str]]:
+    """The static brand tables, plus any live brand they don't already cover.
+
+    KNOWN_BRANDS and BRAND_SEARCH_MAP carry hand-tuned synonyms ("coke",
+    "hul", "pepsi") that cannot be derived from the database, so they are the
+    base and always win - the live list only *adds* brands, via setdefault.
+    That is what lets a brand ingested at runtime be recognised in chat and
+    search without anyone editing this file.
+
+    Cached for BRAND_MENTION_TTL_SECONDS because this runs on every query and
+    list_available_brands() opens a fresh connection. If the database is
+    unreachable the static behaviour stands rather than failing the query.
+    """
+    now = time.monotonic()
+    if _MENTION_CACHE["map"] is not None and now - _MENTION_CACHE["at"] < BRAND_MENTION_TTL_SECONDS:
+        return _MENTION_CACHE["known"], _MENTION_CACHE["map"]
+
+    known = list(KNOWN_BRANDS)
+    mapping = dict(BRAND_SEARCH_MAP)
+    try:
+        from app.services.vector_store import list_available_brands
+
+        covered = {k.lower() for k in known}
+        for brand in list_available_brands():
+            if brand.lower() not in covered:
+                known.append(brand)
+                covered.add(brand.lower())
+            mapping.setdefault(brand.lower(), brand)
+    except Exception:  # noqa: BLE001 - a DB blip must not break intent parsing
+        pass
+
+    _MENTION_CACHE.update(at=now, known=known, map=mapping)
+    return known, mapping
+
+
 def extract_brand_mention(query: str) -> Optional[str]:
     """Detect if a brand name is explicitly mentioned in the query text."""
     if not query:
         return None
     from app.services.brand_registry import BRAND_ALIASES, resolve_parent_brand
     lower = query.lower()
+    known_brands, brand_search_map = _brand_index()
 
     # 1. Check direct search map
-    for alias in sorted(BRAND_SEARCH_MAP.keys(), key=len, reverse=True):
+    for alias in sorted(brand_search_map.keys(), key=len, reverse=True):
         pattern = r"\b" + re.escape(alias) + r"\b"
         if re.search(pattern, lower):
-            return BRAND_SEARCH_MAP[alias]
+            return brand_search_map[alias]
 
     # 2. Check sub-brand aliases (e.g. "oreo", "maggi", "good day")
     sorted_aliases = sorted(BRAND_ALIASES.keys(), key=len, reverse=True)
@@ -190,7 +243,7 @@ def extract_brand_mention(query: str) -> Optional[str]:
         if re.search(pattern, lower):
             parent = resolve_parent_brand(alias)
             # Normalize to canonical known brand name case
-            for kb in KNOWN_BRANDS:
+            for kb in known_brands:
                 if kb.lower() == parent.lower():
                     return kb
             return parent.title()
diff --git a/app/services/vector_store.py b/app/services/vector_store.py
index 68af150..070b1fd 100644
--- a/app/services/vector_store.py
+++ b/app/services/vector_store.py
@@ -4,7 +4,9 @@ from typing import List, Optional, Dict, Any
 
 import json
 import logging
+import os
 import re
+import time
 import psycopg
 
 from app.infrastructure.settings import DATABASE_URL, USE_PGVECTOR, DB_HOST, DB_PORT, DB_NAME, DB_USER, DB_PASSWORD
@@ -367,9 +369,19 @@ def upsert_brand_products(brand: str, products: List[Dict[str, Any]], cleanup: b
             deleted = cur.rowcount
             if deleted:
                 logger.info(f"🗑️ Removed {deleted} stale product(s) from {table_name}")
-    
+
     conn.close()
 
+    # Every write path into the catalog funnels through here, so this is the
+    # one place that has to invalidate the derived views: the brand cards'
+    # counts, and the brand list that chat/search intent parsing scopes on.
+    invalidate_brand_overview_cache()
+    try:
+        from app.services.query_intent import invalidate_brand_mention_cache
+        invalidate_brand_mention_cache()
+    except Exception:  # noqa: BLE001 - cache invalidation must never fail a write
+        pass
+
 
 def get_existing_product_image_id(brand: str, product_name: str) -> Optional[str]:
     """Check if a product with this name exists in the brand table and return its image_id"""
@@ -412,20 +424,45 @@ def _build_sanitized_brand_map() -> Dict[str, str]:
     return seen
 
 
+# Acronyms that .title() would mangle ("itc" -> "Itc"). Only needed for brands
+# whose parent value in BRAND_ALIASES is lowercase and not a real word.
+BRAND_DISPLAY_OVERRIDES = {
+    "itc": "ITC",
+    "grb": "GRB",
+    "hul": "HUL",
+}
+
+
+def display_name_for_suffix(suffix: str, brand_map: Optional[Dict[str, str]] = None) -> str:
+    """Turn a brand table suffix back into the name shown in the UI.
+
+    Shared by list_available_brands() and get_brand_overview() so the sidebar
+    list and the brand cards can never disagree - the frontend passes these
+    strings straight back to /api/brands/{brand}/products, so they must round
+    trip through resolve_parent_brand + _sanitize_name to the same table.
+    """
+    if brand_map is None:
+        brand_map = _build_sanitized_brand_map()
+    override = BRAND_DISPLAY_OVERRIDES.get(suffix)
+    if override:
+        return override
+    return brand_map.get(suffix) or suffix.replace('_', ' ').title()
+
+
 def list_available_brands() -> List[str]:
     """List all available brands that have tables in the database"""
     conn = _connect()
     if not conn:
         return []
-    
+
     brand_map = _build_sanitized_brand_map()
     brands = []
     with conn, conn.cursor() as cur:
         try:
             # Query information_schema for tables starting with brand_
             cur.execute("""
-                SELECT table_name 
-                FROM information_schema.tables 
+                SELECT table_name
+                FROM information_schema.tables
                 WHERE table_schema = 'public' AND table_name LIKE 'brand_%'
             """)
             tables = cur.fetchall()
@@ -434,15 +471,143 @@ def list_available_brands() -> List[str]:
                 table_name = table[0]
                 suffix = table_name[len("brand_"):].lower() if table_name.startswith("brand_") else table_name.lower()
                 # Prefer the original display name from the brand map if available
-                brand_name = brand_map.get(suffix, suffix.replace('_', ' ').title())
-                brands.append(brand_name)
+                brands.append(display_name_for_suffix(suffix, brand_map))
         except Exception as e:
             logger.error(f"Failed to list brands: {e}")
-    
+
     conn.close()
     return sorted(list(set(brands)))
 
 
+BRAND_OVERVIEW_TTL_SECONDS = int(os.getenv("BRAND_OVERVIEW_TTL_SECONDS", "30"))
+
+_OVERVIEW_CACHE: Dict[str, Any] = {"at": 0.0, "data": None}
+
+
+def invalidate_brand_overview_cache() -> None:
+    """Drop the cached brand overview so the next read reflects a fresh write."""
+    _OVERVIEW_CACHE.update(at=0.0, data=None)
+
+
+def get_brand_overview(force_refresh: bool = False) -> List[Dict[str, Any]]:
+    """Per-brand summary rows backing the brand cards on the home page.
+
+    Everything runs on a single connection: _connect() opens a new one each
+    call, so doing this per brand would cost dozens of handshakes on every
+    page load. Results are cached for BRAND_OVERVIEW_TTL_SECONDS and dropped
+    explicitly by upsert_brand_products(), which covers every write path.
+    """
+    now = time.monotonic()
+    if (
+        not force_refresh
+        and _OVERVIEW_CACHE["data"] is not None
+        and now - _OVERVIEW_CACHE["at"] < BRAND_OVERVIEW_TTL_SECONDS
+    ):
+        return _OVERVIEW_CACHE["data"]
+
+    conn = _connect()
+    if not conn:
+        return []
+
+    brand_map = _build_sanitized_brand_map()
+    overview: List[Dict[str, Any]] = []
+    try:
+        with conn, conn.cursor() as cur:
+            # Brand tables predating the current DDL are missing columns until a
+            # write runs _ensure_columns on them, so build each query from the
+            # columns that actually exist. The rest of this module survives that
+            # by selecting *; naming columns here would 500 the whole endpoint.
+            cur.execute(
+                """
+                SELECT table_name, column_name FROM information_schema.columns
+                WHERE table_schema = 'public' AND table_name LIKE 'brand_%'
+                """
+            )
+            table_columns: Dict[str, set] = {}
+            for table_name, column_name in cur.fetchall():
+                table_columns.setdefault(table_name, set()).add(column_name)
+
+            for suffix in sorted(set(_list_brand_table_suffixes(cur))):
+                table_name = f"brand_{suffix}"
+                columns = table_columns.get(table_name, set())
+                has_category = "category" in columns
+
+                try:
+                    if has_category:
+                        cur.execute(
+                            f"""
+                            SELECT COUNT(*),
+                                   COUNT(DISTINCT category)
+                                     FILTER (WHERE category IS NOT NULL AND category <> '')
+                            FROM {table_name}
+                            """
+                        )
+                        row = cur.fetchone()
+                        product_count = int(row[0]) if row else 0
+                        category_count = int(row[1]) if row and row[1] is not None else 0
+                    else:
+                        cur.execute(f"SELECT COUNT(*) FROM {table_name}")
+                        row = cur.fetchone()
+                        product_count = int(row[0]) if row else 0
+                        category_count = 0
+
+                    if product_count == 0:
+                        # An empty table is a leftover, not a brand to advertise.
+                        continue
+
+                    categories: List[str] = []
+                    if has_category:
+                        cur.execute(
+                            f"""
+                            SELECT category FROM {table_name}
+                            WHERE category IS NOT NULL AND category <> ''
+                            GROUP BY category ORDER BY COUNT(*) DESC LIMIT 4
+                            """
+                        )
+                        categories = [r[0] for r in cur.fetchall() if r[0]]
+
+                    img = None
+                    image_cols = [c for c in ("image_id", "image_url", "image_urls") if c in columns]
+                    if "image_url" in columns or "image_urls" in columns:
+                        where = " OR ".join(
+                            f"({c} IS NOT NULL)" for c in ("image_url", "image_urls") if c in columns
+                        )
+                        order = " ORDER BY updated_at DESC" if "updated_at" in columns else ""
+                        cur.execute(
+                            f"SELECT {', '.join(image_cols)} FROM {table_name} "
+                            f"WHERE {where}{order} LIMIT 1"
+                        )
+                        row = cur.fetchone()
+                        img = dict(zip(image_cols, row)) if row else None
+                except Exception as e:
+                    logger.warning("Brand overview skipped %s: %s", table_name, e)
+                    continue
+
+                sample_image_id = (img or {}).get("image_id")
+                sample_image_url = (img or {}).get("image_url") or None
+                if not sample_image_url and img and img.get("image_urls"):
+                    urls = [u for u in img["image_urls"] if u]
+                    sample_image_url = urls[0] if urls else None
+
+                overview.append({
+                    "suffix": suffix,
+                    "display_name": display_name_for_suffix(suffix, brand_map),
+                    "product_count": product_count,
+                    "category_count": category_count,
+                    "categories": categories,
+                    "sample_image_id": sample_image_id,
+                    "sample_image_url": sample_image_url,
+                })
+    except Exception as e:
+        logger.error(f"Failed to build brand overview: {e}")
+    finally:
+        conn.close()
+
+    overview.sort(key=lambda b: b["display_name"].lower())
+    _OVERVIEW_CACHE.update(at=now, data=overview)
+    return overview
+
+
 def get_products_by_brand(brand: str, limit: Optional[int] = None, offset: int = 0,
                            category: Optional[str] = None) -> List[Dict[str, Any]]:
     """Fetch products for a specific brand from its table (plain listing, no ranking).
diff --git a/scripts/seed_sample_data.py b/scripts/seed_sample_data.py
index da0fb69..81702e6 100644
--- a/scripts/seed_sample_data.py
+++ b/scripts/seed_sample_data.py
@@ -20,22 +20,17 @@ Usage:
 from __future__ import annotations
 
 import argparse
-import json
 import logging
 import sys
 from pathlib import Path
-from collections import defaultdict
 
 sys.path.insert(0, str(Path(__file__).resolve().parents[1]))
 
-from app.services.vector_store import ensure_brand_schema, upsert_brand_products, _connect, _sanitize_name  # noqa: E402
-from app.services.brand_registry import resolve_parent_brand  # noqa: E402
+from app.services.brand_sync import SEED_DIR, load_seed_catalogs, seed_brands  # noqa: E402
 
 logging.basicConfig(level=logging.INFO, format="%(asctime)s - %(levelname)s - %(message)s")
 logger = logging.getLogger(__name__)
 
-SEED_DIR = Path(__file__).resolve().parents[1] / "data" / "seed_catalogs"
-
 
 def main() -> None:
     parser = argparse.ArgumentParser(description="Seed pgvector with bundled sample catalogs")
@@ -63,34 +58,11 @@ def main() -> None:
         logger.error("Seed directory not found: %s", SEED_DIR)
         sys.exit(1)
 
-    files = sorted(SEED_DIR.glob("*.json"))
-    if args.only:
-        wanted = [w.lower() for w in args.only]
-        files = [f for f in files if any(w in f.name.lower() for w in wanted)]
-
-    if not files:
-        logger.warning("No matching seed files found in %s", SEED_DIR)
-        return
-
-    # Aggregate products by resolved (canonical) brand so that multiple
+    # Products are aggregated by resolved (canonical) brand so that multiple
     # seed files contributing to the same brand table are upserted as a
     # single batch. This ensures the stale-product cleanup (cleanup=True)
     # doesn't orphan products from a sibling file.
-    brand_products: dict[str, list[dict]] = defaultdict(list)
-    file_brand_map: dict[str, str] = {}
-
-    for f in files:
-        data = json.loads(f.read_text(encoding="utf-8-sig"))
-        products = data.get("products", [])
-        brand = data.get("brand") or (products[0].get("brand_name") if products else None)
-        if not brand or not products:
-            logger.warning("Skipping %s - no brand/products found", f.name)
-            continue
-
-        resolved = resolve_parent_brand(brand)
-        brand_products[resolved].extend(products)
-        file_brand_map[f.name] = resolved
-        logger.info("Read %d products from %s -> resolved brand '%s'", len(products), f.name, resolved)
+    brand_products = load_seed_catalogs(only=args.only)
 
     if not brand_products:
         logger.warning("No valid seed data found in %s", SEED_DIR)
@@ -99,17 +71,7 @@ def main() -> None:
     # Do not drop existing brand tables to preserve user database state.
     # Stale table cleanup disabled per environment requirements.
 
-
-    total = 0
-    for resolved_brand, all_products in brand_products.items():
-        logger.info("Seeding %d product(s) for brand '%s'", len(all_products), resolved_brand)
-        table = ensure_brand_schema(resolved_brand)
-        if not table:
-            logger.error("Could not create/verify table for brand '%s' - is pgvector reachable?", resolved_brand)
-            continue
-        upsert_brand_products(resolved_brand, all_products, cleanup=True)
-        logger.info("Seeded %d products for brand '%s' (table=%s)", len(all_products), resolved_brand, table)
-        total += len(all_products)
+    total = seed_brands(brand_products, cleanup=True)
 
     print(f"\nDone. Seeded {total} products across {len(brand_products)} brand(s) into pgvector.")
     print("Start the API with `uvicorn app.main:app --reload` and try a search/chat query.")
diff --git a/tests/test_brand_registry.py b/tests/test_brand_registry.py
new file mode 100644
index 0000000..78f80a2
--- /dev/null
+++ b/tests/test_brand_registry.py
@@ -0,0 +1,113 @@
+"""
+Guard rails for brand -> parent-brand resolution.
+
+`resolve_parent_brand` decides which `brand_*` table, which S3 folder, and
+which seed catalog file a product lands in. An edit to BRAND_ALIASES that
+quietly changes an existing brand's answer would relocate live rows, so the
+first test pins the answer for every realistic input: all alias keys, all
+parent values, and the `brand` field of every bundled seed catalog.
+
+No database, no network - the registry is a plain dict.
+"""
+from __future__ import annotations
+
+import json
+from pathlib import Path
+
+import pytest
+
+from app.services.brand_registry import BRAND_ALIASES, resolve_parent_brand
+from app.services.vector_store import _sanitize_name
+
+SEED_DIR = Path(__file__).resolve().parents[1] / "data" / "seed_catalogs"
+
+
+def _seed_brand_fields() -> list[str]:
+    """The `brand` value of every seed catalog (skipping non-catalog files)."""
+    brands = []
+    for path in sorted(SEED_DIR.glob("*.json")):
+        try:
+            data = json.loads(path.read_text(encoding="utf-8-sig"))
+        except Exception:
+            continue
+        brand = data.get("brand")
+        if brand:
+            brands.append(brand)
+    return brands
+
+
+# Every seed catalog and the table it must continue to feed. `tata` mapping to
+# hindustan_unilever is not a typo: alias "hul tata tea" claims it, which is
+# where all 121 of that file's products already live.
+EXPECTED_SEED_TABLES = {
+    "amul": "brand_amul",
+    "cadbury": "brand_cadbury",
+    "cavinkare": "brand_cavinkare",
+    "coca-cola": "brand_coca_cola",
+    "colgate-palmolive": "brand_colgate_palmolive",
+    "dabur": "brand_dabur",
+    "godrej": "brand_godrej",
+    "grb": "brand_grb",
+    "hindustan unilever": "brand_hindustan_unilever",
+    "lion dates": "brand_lion_dates",
+    "Manna": "brand_manna",
+    "milky mist": "brand_milky_mist",
+    "naga": "brand_naga",
+    "Nestle": "brand_nestle",
+    "p&g": "brand_p_g",
+    "pepsico": "brand_pepsico",
+    "tata": "brand_hindustan_unilever",
+}
+
+
+@pytest.mark.parametrize("alias,parent", sorted(BRAND_ALIASES.items()))
+def test_every_alias_resolves_to_its_declared_parent(alias: str, parent: str) -> None:
+    assert resolve_parent_brand(alias) == parent
+
+
+# Every parent brand resolves to itself except "sunfeast", which the alias
+# "itc sunfeast" claims for ITC. That collapse predates the word-boundary
+# change and is pinned here so it stays a deliberate quirk rather than drift.
+_NON_SELF_PARENTS = {"sunfeast": "itc"}
+
+
+@pytest.mark.parametrize("parent", sorted(set(BRAND_ALIASES.values())))
+def test_parent_brands_resolve_to_their_pinned_answer(parent: str) -> None:
+    assert resolve_parent_brand(parent) == _NON_SELF_PARENTS.get(parent, parent)
+
+
+def test_seed_catalogs_keep_their_current_tables() -> None:
+    """The load-bearing assertion: no seed file changes destination table."""
+    actual = {
+        brand: f"brand_{_sanitize_name(resolve_parent_brand(brand))}"
+        for brand in _seed_brand_fields()
+    }
+    assert actual == EXPECTED_SEED_TABLES
+
+
+def test_known_sub_brands_still_route_to_their_family() -> None:
+    """Word-boundary matching must not break legitimate sub-brand routing."""
+    assert resolve_parent_brand("Dove") == "hindustan unilever"
+    assert resolve_parent_brand("Silk") == "cadbury"
+    assert resolve_parent_brand("Bingo") == "itc"
+    assert resolve_parent_brand("Sunfeast") == "itc"
+
+
+def test_new_brand_is_not_swallowed_by_a_fragment_match() -> None:
+    """
+    "sun" appears inside "hul sunsilk" but is not a word there, so a new brand
+    called Sun must stay Sun. Under the old substring fallback it silently
+    became "hindustan unilever" - the bug this guards.
+    """
+    assert resolve_parent_brand("Sun") == "Sun"
+    assert resolve_parent_brand("Bing") == "Bing"
+
+
+def test_unknown_brand_passes_through_unchanged() -> None:
+    assert resolve_parent_brand("Totally Made Up Brand") == "Totally Made Up Brand"
+
+
+def test_new_brand_round_trips_to_its_own_table() -> None:
+    """ITC is the worked example: it must own brand_itc, not merge elsewhere."""
+    assert resolve_parent_brand("ITC") == "itc"
+    assert _sanitize_name(resolve_parent_brand("ITC")) == "itc"