diff --git a/runtime/lib/build_manifest.py b/runtime/lib/build_manifest.py
index d92beb0..70222e2 100644
--- a/runtime/lib/build_manifest.py
+++ b/runtime/lib/build_manifest.py
@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-"""Resolve Nextcloud view rows through explicitly configured storage mounts."""
+"""Resolve Nextcloud share rows through configured storage adapters."""
 
 from __future__ import annotations
 
@@ -23,111 +23,194 @@ def validate_view(name: str) -> str:
     return value
 
 
+def sql_literal(value: str) -> str:
+    return "'" + str(value).replace("'", "''") + "'"
+
+
 def read_config(path: Path) -> dict[str, list[tuple[str, Path, str]]]:
     result: dict[str, list[tuple[str, Path, str]]] = {}
     with path.open(encoding="utf-8") as handle:
         for number, line in enumerate(handle, 1):
-            line=line.rstrip("\n")
-            if not line or line.startswith("#"):continue
-            fields=line.split("\t")
-            if len(fields) not in {3,4}:raise ValueError(f"{path}:{number}: expected storage_id, source_prefix, local_mount and optional include_prefix")
-            storage_id,prefix,mount=fields[:3]
-            include_prefix=fields[3] if len(fields)==4 else ""
-            storage_id=storage_id.strip();prefix=prefix.strip("/");include_prefix=include_prefix.strip("/")
-            if not storage_id:raise ValueError(f"{path}:{number}: storage_id is empty")
-            if ".." in PurePosixPath(prefix).parts or ".." in PurePosixPath(include_prefix).parts:raise ValueError(f"{path}:{number}: unsafe prefix")
-            result.setdefault(storage_id,[]).append((prefix,Path(mount),include_prefix))
+            line = line.rstrip("\n")
+            if not line or line.startswith("#"):
+                continue
+            fields = line.split("\t")
+            if len(fields) not in {3, 4}:
+                raise ValueError(f"{path}:{number}: expected storage_id, source_prefix, local_mount and optional include_prefix")
+            storage_id, prefix, mount = fields[:3]
+            include_prefix = fields[3] if len(fields) == 4 else ""
+            storage_id = storage_id.strip()
+            prefix = prefix.strip("/")
+            include_prefix = include_prefix.strip("/")
+            if not storage_id:
+                raise ValueError(f"{path}:{number}: storage_id is empty")
+            if ".." in PurePosixPath(prefix).parts or ".." in PurePosixPath(include_prefix).parts:
+                raise ValueError(f"{path}:{number}: unsafe prefix")
+            result.setdefault(storage_id, []).append((prefix, Path(mount), include_prefix))
     return result
 
 
-def run_query(args: argparse.Namespace, env: dict[str,str], sql: str) -> subprocess.CompletedProcess[str]:
-    command=["psql","-X","-A","-F","\t","-t","-v","ON_ERROR_STOP=1","-h",args.host,"-p",str(args.port),"-U",args.user,"-d",args.database,"-c",sql]
-    return subprocess.run(command,env=env,check=False,text=True,capture_output=True)
+def run_query(args: argparse.Namespace, env: dict[str, str], sql: str) -> subprocess.CompletedProcess[str]:
+    command = [
+        "psql", "-X", "-A", "-F", "\t", "-t", "-v", "ON_ERROR_STOP=1",
+        "-h", args.host, "-p", str(args.port), "-U", args.user, "-d", args.database, "-c", sql,
+    ]
+    return subprocess.run(command, env=env, check=False, text=True, capture_output=True)
 
 
 def query_rows(args: argparse.Namespace) -> list[list[str]]:
-    password=args.password_file.read_text(encoding="utf-8").strip();env=os.environ.copy();env["PGPASSWORD"]=password;view=validate_view(args.view)
-    modern_sql=f"SELECT share_id, item_type, display_name, storage_id, source_path FROM {view} ORDER BY share_id"
-    completed=run_query(args,env,modern_sql)
-    if completed.returncode==0:return list(csv.reader(completed.stdout.splitlines(),delimiter="\t"))
-    if "item_type" not in completed.stderr or "does not exist" not in completed.stderr:raise RuntimeError(completed.stderr.strip() or "Nextcloud source view query failed")
-    legacy_sql=f"SELECT share_id, display_name, storage_id, source_path FROM {view} ORDER BY share_id"
-    completed=run_query(args,env,legacy_sql)
-    if completed.returncode!=0:raise RuntimeError(completed.stderr.strip() or "legacy Nextcloud source view query failed")
-    rows=[]
-    for row in csv.reader(completed.stdout.splitlines(),delimiter="\t"):
-        if len(row)==4:
-            share_id,display_name,storage_id,source_path=row;rows.append([share_id,"",display_name,storage_id,source_path])
-        else:rows.append(row)
+    password = args.password_file.read_text(encoding="utf-8").strip()
+    env = os.environ.copy()
+    env["PGPASSWORD"] = password
+    view = validate_view(args.view)
+    where = ""
+    if args.access_user:
+        where = " WHERE lower(access_user) = lower(" + sql_literal(args.access_user) + ")"
+    modern_sql = f"SELECT share_id, item_type, display_name, storage_id, source_path FROM {view}{where} ORDER BY share_id"
+    completed = run_query(args, env, modern_sql)
+    if completed.returncode == 0:
+        return list(csv.reader(completed.stdout.splitlines(), delimiter="\t"))
+    if args.access_user:
+        raise RuntimeError(completed.stderr.strip() or "Nextcloud user-filtered source query failed")
+    if "item_type" not in completed.stderr or "does not exist" not in completed.stderr:
+        raise RuntimeError(completed.stderr.strip() or "Nextcloud source view query failed")
+    legacy_sql = f"SELECT share_id, display_name, storage_id, source_path FROM {view} ORDER BY share_id"
+    completed = run_query(args, env, legacy_sql)
+    if completed.returncode != 0:
+        raise RuntimeError(completed.stderr.strip() or "legacy Nextcloud source view query failed")
+    rows: list[list[str]] = []
+    for row in csv.reader(completed.stdout.splitlines(), delimiter="\t"):
+        if len(row) == 4:
+            share_id, display_name, storage_id, source_path = row
+            rows.append([share_id, "", display_name, storage_id, source_path])
+        else:
+            rows.append(row)
     return rows
 
 
 def contained_join(root: Path, relative: str) -> Path:
-    parts=PurePosixPath(relative).parts
-    if relative.startswith("/") or ".." in parts:raise ValueError(f"unsafe source path: {relative}")
+    parts = PurePosixPath(relative).parts
+    if relative.startswith("/") or ".." in parts:
+        raise ValueError(f"unsafe source path: {relative}")
     return root.joinpath(*parts)
 
 
 def matches_prefix(path: str, prefix: str) -> bool:
-    if not prefix:return True
-    return path==prefix or path.startswith(prefix+"/")
+    return not prefix or path == prefix or path.startswith(prefix + "/")
 
 
-def resolve_adapter(adapters: dict[str,list[tuple[str,Path,str]]],storage_id: str,source_path: str) -> tuple[str,Path,str] | None:
-    relative=source_path.strip("/")
-    matches=[]
-    for prefix,mount,include_prefix in adapters.get(storage_id,[]):
-        if not matches_prefix(relative,prefix):continue
-        mapped_relative=relative[len(prefix):].lstrip("/") if prefix else relative
-        if not matches_prefix(mapped_relative,include_prefix):continue
-        matches.append((prefix,mount,include_prefix))
-    if not matches:return None
-    matches.sort(key=lambda item:(len(item[0]),len(item[2])),reverse=True)
-    return matches[0]
+def resolve_adapter(adapters: dict[str, list[tuple[str, Path, str]]], storage_id: str, source_path: str) -> tuple[str, Path, str] | None:
+    relative = source_path.strip("/")
+    matches: list[tuple[str, Path, str]] = []
+    for prefix, mount, include_prefix in adapters.get(storage_id, []):
+        if not matches_prefix(relative, prefix):
+            continue
+        mapped_relative = relative[len(prefix):].lstrip("/") if prefix else relative
+        if not matches_prefix(mapped_relative, include_prefix):
+            continue
+        matches.append((prefix, mount, include_prefix))
+    if not matches:
+        return None
+    matches.sort(key=lambda item: (len(item[0]), len(item[2])), reverse=True)
+    best_score = (len(matches[0][0]), len(matches[0][2]))
+    best = {(item[0], str(item[1]), item[2]): item for item in matches if (len(item[0]), len(item[2])) == best_score}
+    if len(best) != 1:
+        raise RuntimeError(f"storage adapter is ambiguous for {storage_id}")
+    return next(iter(best.values()))
 
 
-def build(args: argparse.Namespace) -> dict[str,object]:
-    validate_view(args.view);adapters=read_config(args.storage_config);rows=query_rows(args)
-    if not rows and not args.allow_empty:raise RuntimeError("Nextcloud returned no Showcase shares; refusing an empty manifest")
-    manifest=[];errors=[];folder_count=0;file_count=0
+def build(args: argparse.Namespace) -> dict[str, object]:
+    validate_view(args.view)
+    adapters = read_config(args.storage_config)
+    rows = query_rows(args)
+    if not rows and not args.allow_empty:
+        raise RuntimeError("Nextcloud returned no matching sources; refusing an empty manifest")
+    manifest: list[str] = []
+    errors: list[str] = []
+    folder_count = 0
+    file_count = 0
     for row in rows:
-        if len(row)!=5:errors.append(f"invalid database row with {len(row)} columns");continue
-        share_id,item_type,display_name,storage_id,source_path=row;item_type=item_type.strip().lower();relative=source_path.strip("/")
-        if item_type and item_type not in {"folder","file"}:errors.append(f"share {share_id}: unsupported item_type {item_type!r}");continue
-        adapter=resolve_adapter(adapters,storage_id,relative)
-        if not adapter:continue
-        prefix,mount,_include_prefix=adapter
-        if prefix:relative=relative[len(prefix):].lstrip("/")
-        source=contained_join(mount,relative)
-        if not mount.is_mount():errors.append(f"share {share_id}: storage mount unavailable: {mount}");continue
+        if len(row) != 5:
+            errors.append(f"invalid database row with {len(row)} columns")
+            continue
+        share_id, item_type, display_name, storage_id, source_path = row
+        item_type = item_type.strip().lower()
+        relative = source_path.strip("/")
+        if item_type and item_type not in {"folder", "file"}:
+            errors.append(f"source {share_id}: unsupported item_type {item_type!r}")
+            continue
+        try:
+            adapter = resolve_adapter(adapters, storage_id, relative)
+        except RuntimeError as error:
+            errors.append(f"source {share_id}: {error}")
+            continue
+        if not adapter:
+            continue
+        prefix, mount, _include_prefix = adapter
+        if prefix:
+            relative = relative[len(prefix):].lstrip("/")
+        source = contained_join(mount, relative)
+        if not mount.is_mount():
+            errors.append(f"source {share_id}: storage mount unavailable: {mount}")
+            continue
         if not item_type:
-            if source.is_dir():item_type="folder"
-            elif source.is_file():item_type="file"
-            else:errors.append(f"share {share_id}: source unavailable: {source}");continue
-        if item_type=="folder":
-            if not source.is_dir():errors.append(f"share {share_id}: source directory unavailable: {source}");continue
-            folder_count+=1
+            if source.is_dir():
+                item_type = "folder"
+            elif source.is_file():
+                item_type = "file"
+            else:
+                errors.append(f"source {share_id}: source unavailable: {source}")
+                continue
+        if item_type == "folder":
+            if not source.is_dir():
+                errors.append(f"source {share_id}: source directory unavailable: {source}")
+                continue
+            folder_count += 1
         else:
-            if not source.is_file():errors.append(f"share {share_id}: source file unavailable: {source}");continue
-            file_count+=1
-        if "\t" in display_name or "\n" in display_name or "\r" in display_name:errors.append(f"share {share_id}: display name contains unsupported control characters");continue
-        source_text=str(source)
-        if "\t" in source_text or "\n" in source_text or "\r" in source_text:errors.append(f"share {share_id}: source path contains unsupported control characters");continue
+            if not source.is_file():
+                errors.append(f"source {share_id}: source file unavailable: {source}")
+                continue
+            file_count += 1
+        if any(char in display_name for char in ("\t", "\n", "\r")):
+            errors.append(f"source {share_id}: display name contains unsupported control characters")
+            continue
+        source_text = str(source)
+        if any(char in source_text for char in ("\t", "\n", "\r")):
+            errors.append(f"source {share_id}: source path contains unsupported control characters")
+            continue
         manifest.append(f"{share_id}\t{item_type}\t{display_name.lstrip('/')}\t{source}")
-    if errors:raise RuntimeError("; ".join(errors))
-    if not manifest and rows and not args.allow_empty:raise RuntimeError("no Showcase shares match the selected directories")
-    args.output.parent.mkdir(parents=True,exist_ok=True)
-    with tempfile.NamedTemporaryFile("w",encoding="utf-8",dir=args.output.parent,delete=False) as handle:
-        handle.write("\n".join(manifest)+("\n" if manifest else ""));temporary=Path(handle.name)
+    if errors:
+        raise RuntimeError("; ".join(errors))
+    if not manifest and rows and not args.allow_empty:
+        raise RuntimeError("no Nextcloud sources match the configured storage adapters")
+    args.output.parent.mkdir(parents=True, exist_ok=True)
+    with tempfile.NamedTemporaryFile("w", encoding="utf-8", dir=args.output.parent, delete=False) as handle:
+        handle.write("\n".join(manifest) + ("\n" if manifest else ""))
+        temporary = Path(handle.name)
     temporary.replace(args.output)
-    return {"shares":len(manifest),"folders":folder_count,"files":file_count,"manifest":str(args.output)}
+    return {"sources": len(manifest), "folders": folder_count, "files": file_count, "manifest": str(args.output)}
 
 
 def main() -> int:
-    parser=argparse.ArgumentParser();parser.add_argument("--host",required=True);parser.add_argument("--port",type=int,default=5432);parser.add_argument("--database",required=True);parser.add_argument("--user",required=True);parser.add_argument("--password-file",required=True,type=Path);parser.add_argument("--view",default="piwigo_showcase_sources");parser.add_argument("--storage-config",required=True,type=Path);parser.add_argument("--output",required=True,type=Path);parser.add_argument("--allow-empty",action="store_true");args=parser.parse_args()
-    try:print(json.dumps(build(args),ensure_ascii=False))
-    except Exception as error:print(f"manifest: {error}",file=sys.stderr);return 1
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--host", required=True)
+    parser.add_argument("--port", type=int, default=5432)
+    parser.add_argument("--database", required=True)
+    parser.add_argument("--user", required=True)
+    parser.add_argument("--password-file", required=True, type=Path)
+    parser.add_argument("--view", required=True)
+    parser.add_argument("--access-user", default="")
+    parser.add_argument("--storage-config", required=True, type=Path)
+    parser.add_argument("--output", required=True, type=Path)
+    parser.add_argument("--allow-empty", action="store_true")
+    args = parser.parse_args()
+    try:
+        print(json.dumps(build(args), ensure_ascii=False))
+    except Exception as error:
+        print(f"manifest: {error}", file=sys.stderr)
+        return 1
     return 0
 
 
-if __name__=="__main__":raise SystemExit(main())
\ No newline at end of file
+if __name__ == "__main__":
+    raise SystemExit(main())