Merge latest origin/main into gatekeeper/fix-2057-1

docs/src/python/python.md

@@ -68,6 +68,18 @@ listing a storage directory.
 
 ::: lancedb.functions.PythonEnvironmentSpec
 
+::: lancedb.functions.udf
+
+::: lancedb.functions.UdfDefinition
+
+::: lancedb.functions.FunctionRegistrationRequest
+
+::: lancedb.functions.FunctionArtifactRequest
+
+::: lancedb.functions.FunctionArtifactContent
+
+::: lancedb.functions.PythonAdapterSpec
+
 ::: lancedb.functions.FunctionVersion
 
 ::: lancedb.functions.PythonRuntimeSpec

python/python/lancedb/__init__.py

@@ -23,10 +23,14 @@ from .expr import Expr, col, lit, func
 from .schema import blob, vector, BlobType
 from .job import AsyncJob, Job
 from .functions import (
+    FunctionArtifactRequest as FunctionArtifactRequest,
     FunctionApplication as FunctionApplication,
     FunctionBinding as FunctionBinding,
+    FunctionRegistrationRequest as FunctionRegistrationRequest,
     FunctionVersion as FunctionVersion,
     PythonRuntimeSpec as PythonRuntimeSpec,
+    UdfDefinition as UdfDefinition,
+    udf as udf,
 )
 from .table import AsyncTable, Table
 from .types import BaseTokenizerType

python/python/lancedb/_lancedb.pyi

@@ -147,6 +147,8 @@ class Connection(object):
         limit: Optional[int],
     ) -> list[str]: ...  # Deprecated: Use list_tables instead
     def job(self, job_id: str) -> Job: ...
+    async def create_function_async(self, request_json: str) -> FunctionJob: ...
+    async def get_function(self, name: str, version: str) -> str: ...
     async def list_jobs(self) -> List[JobInfo]: ...
     async def get_job(self, job_id: str) -> Optional[JobDescription]: ...
     async def cancel_job(self, job_id: str) -> bool: ...
@@ -226,6 +228,13 @@ class Job:
     async def wait(self) -> None: ...
     async def cancel(self) -> None: ...
 
+class FunctionJob:
+    @property
+    def id(self) -> Optional[str]: ...
+    async def status(self) -> str: ...
+    async def wait(self) -> str: ...
+    async def cancel(self) -> None: ...
+
 class JobInfo:
     @property
     def job_id(self) -> str: ...

python/python/lancedb/db.py

@@ -45,7 +45,8 @@ from lance_namespace.errors import NamespaceNotEmptyError, TableNotFoundError
 
 from . import __version__
 from ._lancedb import connect as lancedb_connect  # type: ignore
-from .job import AsyncJob, Job
+from .functions import FunctionVersion, UdfDefinition
+from .job import AsyncJob, Job, _function_job
 from .table import (
     AsyncTable,
     LanceTable,
@@ -616,6 +617,31 @@ class DBConnection(EnforceOverrides):
         """
         raise NotImplementedError("serialize is not supported for this connection type")
 
+    def create_function(self, definition: UdfDefinition) -> FunctionVersion:
+        """Register a scalar Python UDF and wait for its immutable version.
+
+        This is the blocking counterpart of :meth:`create_function_async`.
+        Local connections raise ``NotImplementedError``.
+        """
+        return self.create_function_async(definition).wait()
+
+    def create_function_async(self, definition: UdfDefinition) -> Job[FunctionVersion]:
+        """Register a scalar Python UDF through the remote Function catalog.
+
+        Submission returns a typed job. The immutable Function version becomes
+        available only when :meth:`Job.wait` succeeds. Local connections raise
+        ``NotImplementedError``.
+        """
+        raise NotImplementedError(
+            "Function catalog operations are not supported for this connection type"
+        )
+
+    def get_function(self, name: str, *, version: str) -> FunctionVersion:
+        """Open one exact immutable Function version from the remote catalog."""
+        raise NotImplementedError(
+            "Function catalog operations are not supported for this connection type"
+        )
+
     def job(self, job_id: str) -> Job:
         """A [Job][lancedb.job.Job] handle for a server-side job by id.
 
@@ -1256,6 +1282,15 @@ class LanceDBConnection(DBConnection):
         """
         return Job(self._conn.job(job_id))
 
+    @override
+    def create_function_async(self, definition: UdfDefinition) -> Job[FunctionVersion]:
+        job = LOOP.run(self._conn.create_function_async(definition))
+        return Job(job)
+
+    @override
+    def get_function(self, name: str, *, version: str) -> FunctionVersion:
+        return LOOP.run(self._conn.get_function(name, version=version))
+
     @override
     def list_jobs(self) -> List[JobInfo]:
         """List server-side jobs across the database's tables."""
@@ -2023,6 +2058,25 @@ class AsyncConnection(object):
         """
         return AsyncJob(self._inner.job(job_id))
 
+    async def create_function_async(
+        self, definition: UdfDefinition
+    ) -> AsyncJob[FunctionVersion]:
+        """Register a scalar Python UDF through the remote Function catalog.
+
+        The returned typed job resolves to the immutable Function version.
+        Local connections raise ``NotImplementedError``.
+        """
+        if not isinstance(definition, UdfDefinition):
+            raise TypeError("create_function_async requires a @udf definition")
+        inner = await self._inner.create_function_async(
+            definition.registration_request.to_canonical_json()
+        )
+        return _function_job(inner)
+
+    async def get_function(self, name: str, *, version: str) -> FunctionVersion:
+        """Open one exact immutable Function version from the remote catalog."""
+        return FunctionVersion.from_json(await self._inner.get_function(name, version))
+
     async def list_jobs(self) -> List[JobInfo]:
         """List server-side jobs across the database's tables."""
         return await self._inner.list_jobs()

python/python/lancedb/functions.py

@@ -9,10 +9,32 @@ environment bake, secret resolution, and execution are owned by Sophon.
 
 from __future__ import annotations
 
+import ast
+import base64
+import functools
+import hashlib
+import inspect
 import json
+import math
+import re
+import sys
+import textwrap
+import types
 from collections.abc import Mapping
-from typing import Any, Optional
+from datetime import date, datetime
+from typing import (
+    Annotated,
+    Any,
+    Callable,
+    Optional,
+    Union,
+    get_args,
+    get_origin,
+    get_type_hints,
+    overload,
+)
 
+import pyarrow as pa
 from pydantic import (
     BaseModel,
     ConfigDict,
@@ -126,18 +148,10 @@ class _RemoteValue(BaseModel):
 class _OpenRemoteValue(_RemoteValue):
     """Forward-readable value whose extras stay out of canonical encoding."""
 
-    if _PYDANTIC_V2:
-        model_config = {"extra": "allow", "frozen": True}
-    else:
-
-        class Config:
-            allow_mutation = False
-            extra = "allow"
+    model_config = ConfigDict(extra="allow", frozen=True)
 
     def _unknown_field_names(self) -> set[str]:
-        if _PYDANTIC_V2:
-            return set((self.__pydantic_extra__ or {}).keys())
-        return set(self.__dict__) - set(self.__fields__)
+        return set((self.__pydantic_extra__ or {}).keys())
 
 
 class FunctionArtifact(_RemoteValue):
@@ -148,6 +162,30 @@ class FunctionArtifact(_RemoteValue):
     entrypoint: str
 
 
+class FunctionArtifactContent(_RemoteValue):
+    """Encoded artifact bytes uploaded during remote registration."""
+
+    encoding: str
+    data: str
+
+
+class PythonAdapterSpec(_RemoteValue):
+    """Internal scalar-callable to Arrow-batch adapter selection."""
+
+    kind: str
+    version: _UInt32
+
+
+class FunctionArtifactRequest(_RemoteValue):
+    """Source artifact uploaded while registering a Function."""
+
+    kind: str
+    digest: str
+    entrypoint: str
+    content: FunctionArtifactContent
+    adapter: PythonAdapterSpec
+
+
 class FunctionParameter(_RemoteValue):
     name: str
     arrow_type: str
@@ -228,6 +266,20 @@ class FunctionVersion(_RemoteValue):
     created_at: str
 
 
+class FunctionRegistrationRequest(_RemoteValue):
+    """Stable remote registration envelope produced by :func:`udf`.
+
+    Only secret names are represented. Secret values are resolved inside the
+    remote service and have no client request field.
+    """
+
+    name: str
+    artifact: FunctionArtifactRequest
+    signature: FunctionSignature
+    runtime: PythonRuntimeSpec
+    required_secrets: tuple[str, ...] = ()
+
+
 class FunctionVersionRef(_OpenRemoteValue):
     name: str
     version: str
@@ -361,13 +413,489 @@ class RefreshColumnResult(_RemoteValue):
         return self.published_version
 
 
+_FUNCTION_NAME = re.compile(r"^[A-Za-z_][A-Za-z0-9_.-]*$")
+_SECRET_NAME = re.compile(r"^[A-Za-z_][A-Za-z0-9_]*$")
+
+
+def _canonical_arrow_type(data_type: pa.DataType) -> str:
+    primitive_types = (
+        (pa.bool_(), "bool"),
+        (pa.int8(), "int8"),
+        (pa.int16(), "int16"),
+        (pa.int32(), "int32"),
+        (pa.int64(), "int64"),
+        (pa.uint8(), "uint8"),
+        (pa.uint16(), "uint16"),
+        (pa.uint32(), "uint32"),
+        (pa.uint64(), "uint64"),
+        (pa.float16(), "float16"),
+        (pa.float32(), "float32"),
+        (pa.float64(), "float64"),
+        (pa.string(), "utf8"),
+        (pa.large_utf8(), "large_utf8"),
+        (pa.binary(), "binary"),
+        (pa.large_binary(), "large_binary"),
+        (pa.date32(), "date32"),
+        (pa.date64(), "date64"),
+    )
+    for candidate, name in primitive_types:
+        if data_type == candidate:
+            return name
+    if pa.types.is_fixed_size_binary(data_type):
+        return f"fixed_size_binary[{data_type.byte_width}]"
+    if pa.types.is_list(data_type):
+        return f"list<{_canonical_arrow_type(data_type.value_type)}>"
+    if pa.types.is_large_list(data_type):
+        return f"large_list<{_canonical_arrow_type(data_type.value_type)}>"
+    if pa.types.is_fixed_size_list(data_type):
+        return (
+            f"fixed_size_list<{_canonical_arrow_type(data_type.value_type)}>"
+            f"[{data_type.list_size}]"
+        )
+    if pa.types.is_struct(data_type):
+        fields = ",".join(
+            f"{field.name}:{_canonical_arrow_type(field.type)}" for field in data_type
+        )
+        return f"struct<{fields}>"
+    if pa.types.is_timestamp(data_type):
+        timezone = f",tz={data_type.tz}" if data_type.tz is not None else ""
+        return f"timestamp[{data_type.unit}{timezone}]"
+    if pa.types.is_time32(data_type) or pa.types.is_time64(data_type):
+        return f"time[{data_type.unit}]"
+    if pa.types.is_duration(data_type):
+        return f"duration[{data_type.unit}]"
+    if pa.types.is_decimal(data_type):
+        bit_width = data_type.bit_width
+        return f"decimal{bit_width}({data_type.precision},{data_type.scale})"
+    raise TypeError(f"unsupported Arrow type for Function signature: {data_type}")
+
+
+def _annotation_type(annotation: Any) -> tuple[pa.DataType, bool]:
+    nullable = False
+    origin = get_origin(annotation)
+    if origin in (Union, types.UnionType):
+        arguments = get_args(annotation)
+        non_none = tuple(
+            argument for argument in arguments if argument is not type(None)
+        )
+        if len(non_none) != 1 or len(non_none) == len(arguments):
+            raise TypeError(f"unsupported union annotation: {annotation!r}")
+        annotation = non_none[0]
+        nullable = True
+
+    origin = get_origin(annotation)
+    if origin is Annotated:
+        base, *metadata = get_args(annotation)
+        arrow_types = [value for value in metadata if isinstance(value, pa.DataType)]
+        if len(arrow_types) != 1:
+            raise TypeError(
+                "Annotated Function types require exactly one PyArrow DataType"
+            )
+        _, base_nullable = _annotation_type(base)
+        return arrow_types[0], nullable or base_nullable
+
+    if isinstance(annotation, pa.DataType):
+        return annotation, nullable
+    if annotation is bool:
+        return pa.bool_(), nullable
+    if annotation is int:
+        return pa.int64(), nullable
+    if annotation is float:
+        return pa.float64(), nullable
+    if annotation is str:
+        return pa.string(), nullable
+    if annotation is bytes:
+        return pa.binary(), nullable
+    if annotation is date:
+        return pa.date32(), nullable
+    if annotation is datetime:
+        return pa.timestamp("us"), nullable
+    if get_origin(annotation) is list:
+        arguments = get_args(annotation)
+        if len(arguments) != 1:
+            raise TypeError(f"unsupported list annotation: {annotation!r}")
+        value_type, value_nullable = _annotation_type(arguments[0])
+        if value_nullable:
+            raise TypeError("nullable Function list elements are not supported")
+        return pa.list_(value_type), nullable
+    raise TypeError(f"unsupported Function annotation: {annotation!r}")
+
+
+def _callable_parameters(function: Callable[..., Any]) -> tuple[inspect.Parameter, ...]:
+    parameters = tuple(inspect.signature(function).parameters.values())
+    for parameter in parameters:
+        if parameter.kind in (
+            inspect.Parameter.POSITIONAL_ONLY,
+            inspect.Parameter.VAR_POSITIONAL,
+            inspect.Parameter.VAR_KEYWORD,
+        ):
+            raise TypeError("Function callables require named, non-variadic parameters")
+        if parameter.default is not inspect.Parameter.empty:
+            raise TypeError("Function callable defaults are not supported")
+    return parameters
+
+
+def _function_output(output: pa.DataType | pa.Field | pa.Schema) -> FunctionOutput:
+    if isinstance(output, pa.Schema):
+        fields = tuple(output)
+    elif isinstance(output, pa.Field) and pa.types.is_struct(output.type):
+        if output.nullable:
+            raise ValueError("Function output must be non-nullable")
+        fields = tuple(output.type)
+    elif isinstance(output, pa.DataType) and pa.types.is_struct(output):
+        fields = tuple(output)
+    else:
+        field = (
+            output
+            if isinstance(output, pa.Field)
+            else pa.field("result", output, nullable=False)
+        )
+        if not isinstance(field, pa.Field):
+            raise TypeError(
+                "output_schema must be a PyArrow DataType, Field, or Schema"
+            )
+        if field.nullable:
+            raise ValueError("Function output must be non-nullable")
+        return FunctionOutput(
+            kind="scalar",
+            arrow_type=_canonical_arrow_type(field.type),
+            nullable=False,
+        )
+
+    if not fields:
+        raise ValueError("named-struct Function output must contain at least one field")
+    if any(field.nullable for field in fields):
+        raise ValueError("Function output fields must be non-nullable")
+    names = [field.name for field in fields]
+    if len(set(names)) != len(names):
+        raise ValueError("Function output field names must be unique")
+    return FunctionOutput(
+        kind="named_struct",
+        fields=tuple(
+            FunctionResultField(
+                name=field.name,
+                arrow_type=_canonical_arrow_type(field.type),
+                nullable=False,
+            )
+            for field in fields
+        ),
+    )
+
+
+def _infer_signature(
+    function: Callable[..., Any],
+    input_schema: Optional[pa.Schema],
+    output_schema: Optional[pa.DataType | pa.Field | pa.Schema],
+) -> FunctionSignature:
+    parameters = _callable_parameters(function)
+    if (input_schema is None) != (output_schema is None):
+        raise ValueError("input_schema and output_schema must be provided together")
+
+    if input_schema is not None:
+        if not isinstance(input_schema, pa.Schema):
+            raise TypeError("input_schema must be a PyArrow Schema")
+        expected = tuple(parameter.name for parameter in parameters)
+        actual = tuple(input_schema.names)
+        if actual != expected:
+            raise ValueError(
+                "input_schema fields must exactly match callable parameters in order: "
+                f"expected {expected!r}, got {actual!r}"
+            )
+        inputs = tuple(
+            FunctionParameter(
+                name=field.name,
+                arrow_type=_canonical_arrow_type(field.type),
+                nullable=field.nullable,
+            )
+            for field in input_schema
+        )
+        return FunctionSignature(inputs=inputs, output=_function_output(output_schema))
+
+    try:
+        annotations = get_type_hints(function, include_extras=True)
+    except Exception as error:
+        raise TypeError(f"failed to resolve Function annotations: {error}") from error
+    missing = [
+        parameter.name for parameter in parameters if parameter.name not in annotations
+    ]
+    if missing or "return" not in annotations:
+        names = missing + ([] if "return" in annotations else ["return"])
+        raise TypeError(f"missing Function annotations: {names!r}")
+    inputs = []
+    for parameter in parameters:
+        data_type, nullable = _annotation_type(annotations[parameter.name])
+        inputs.append(
+            FunctionParameter(
+                name=parameter.name,
+                arrow_type=_canonical_arrow_type(data_type),
+                nullable=nullable,
+            )
+        )
+    output_type, output_nullable = _annotation_type(annotations["return"])
+    if output_nullable:
+        raise ValueError("Function output must be non-nullable")
+    return FunctionSignature(
+        inputs=tuple(inputs),
+        output=_function_output(pa.field("result", output_type, nullable=False)),
+    )
+
+
+def _is_udf_decorator(node: ast.expr) -> bool:
+    if isinstance(node, ast.Call):
+        node = node.func
+    return (isinstance(node, ast.Name) and node.id == "udf") or (
+        isinstance(node, ast.Attribute) and node.attr == "udf"
+    )
+
+
+def _literal_source(value: Any) -> str:
+    if value is None or type(value) in (bool, int, str, bytes):
+        return repr(value)
+    if type(value) is float and math.isfinite(value):
+        return repr(value)
+    if type(value) is tuple:
+        children = ", ".join(_literal_source(child) for child in value)
+        if len(value) == 1:
+            children += ","
+        return f"({children})"
+    raise TypeError(
+        "Function source references an unsupported global value of type "
+        f"{type(value).__name__}"
+    )
+
+
+def _package_source(function: Callable[..., Any]) -> bytes:
+    if not inspect.isfunction(function) or inspect.iscoroutinefunction(function):
+        raise TypeError("@udf requires a synchronous Python function")
+    try:
+        source = textwrap.dedent(inspect.getsource(function))
+    except (OSError, TypeError) as error:
+        raise ValueError("@udf requires inspectable Python source") from error
+    module = ast.parse(source)
+    definitions = [
+        node
+        for node in module.body
+        if isinstance(node, (ast.FunctionDef, ast.AsyncFunctionDef))
+        and node.name == function.__name__
+    ]
+    if len(definitions) != 1 or not isinstance(definitions[0], ast.FunctionDef):
+        raise ValueError("@udf source must contain exactly one synchronous function")
+    definition = definitions[0]
+    if any(not _is_udf_decorator(decorator) for decorator in definition.decorator_list):
+        raise ValueError("@udf cannot package additional Python decorators")
+    definition.decorator_list = []
+
+    closure = inspect.getclosurevars(function)
+    if closure.nonlocals:
+        raise ValueError("@udf cannot package functions that capture closure values")
+    if closure.unbound:
+        raise ValueError(
+            f"@udf source contains unresolved global names: {sorted(closure.unbound)!r}"
+        )
+    globals_source = []
+    for name, value in sorted(closure.globals.items()):
+        if isinstance(value, types.ModuleType):
+            globals_source.append(f"import {value.__name__} as {name}")
+        else:
+            globals_source.append(f"{name} = {_literal_source(value)}")
+
+    function_source = ast.unparse(definition)
+    parts = ["from __future__ import annotations"]
+    if globals_source:
+        parts.extend(["", *globals_source])
+    parts.extend(["", function_source, ""])
+    return "\n".join(parts).encode("utf-8")
+
+
+class UdfDefinition:
+    """A scalar Python callable prepared for remote Function registration.
+
+    Instances are created with :func:`udf`. Calling an instance executes the
+    original scalar Python function, which keeps local unit testing ordinary.
+    Remote execution adapts that scalar callable to the internal Arrow batch
+    ABI described by the registration artifact.
+    """
+
+    def __init__(
+        self,
+        function: Callable[..., Any],
+        *,
+        name: Optional[str],
+        input_schema: Optional[pa.Schema],
+        output_schema: Optional[pa.DataType | pa.Field | pa.Schema],
+        pip: tuple[str, ...],
+        env: Mapping[str, str],
+        secrets: tuple[str, ...],
+        python_version: Optional[str],
+    ):
+        function_name = name or function.__name__
+        if not _FUNCTION_NAME.fullmatch(function_name):
+            raise ValueError(f"invalid Function name: {function_name!r}")
+        packages = tuple(sorted(set(pip)))
+        if any(not package or package != package.strip() for package in packages):
+            raise ValueError("pip requirements must be non-empty and trimmed")
+        environment = dict(env)
+        if any(
+            not isinstance(key, str) or not isinstance(value, str)
+            for key, value in environment.items()
+        ):
+            raise TypeError("Function env keys and values must be strings")
+        required_secrets = tuple(sorted(set(secrets)))
+        invalid_secrets = [
+            secret for secret in required_secrets if not _SECRET_NAME.fullmatch(secret)
+        ]
+        if invalid_secrets:
+            raise ValueError(f"invalid Function secret names: {invalid_secrets!r}")
+        overlap = set(environment) & set(required_secrets)
+        if overlap:
+            raise ValueError(
+                f"Function env and secret names must be disjoint: {sorted(overlap)!r}"
+            )
+
+        signature = _infer_signature(function, input_schema, output_schema)
+        source = _package_source(function)
+        digest = f"sha256:{hashlib.sha256(source).hexdigest()}"
+        runtime = PythonRuntimeSpec(
+            kind="python",
+            python_version=python_version
+            or f"{sys.version_info.major}.{sys.version_info.minor}",
+            environment=PythonEnvironmentSpec(kind="pip", packages=packages),
+            env=environment,
+        )
+        self._function = function
+        self._request = FunctionRegistrationRequest(
+            name=function_name,
+            artifact=FunctionArtifactRequest(
+                kind="python_callable",
+                digest=digest,
+                entrypoint=function.__name__,
+                content=FunctionArtifactContent(
+                    encoding="base64",
+                    data=base64.b64encode(source).decode("ascii"),
+                ),
+                adapter=PythonAdapterSpec(
+                    kind="scalar_to_arrow_batch",
+                    version=1,
+                ),
+            ),
+            signature=signature,
+            runtime=runtime,
+            required_secrets=required_secrets,
+        )
+        functools.update_wrapper(self, function)
+
+    @property
+    def registration_request(self) -> FunctionRegistrationRequest:
+        """The immutable request sent by ``create_function_async``."""
+        return self._request
+
+    def __call__(self, *args, **kwargs):
+        return self._function(*args, **kwargs)
+
+
+@overload
+def udf(function: Callable[..., Any]) -> UdfDefinition: ...
+
+
+@overload
+def udf(
+    function: None = None,
+    *,
+    name: Optional[str] = None,
+    input_schema: Optional[pa.Schema] = None,
+    output_schema: Optional[pa.DataType | pa.Field | pa.Schema] = None,
+    pip: tuple[str, ...] | list[str] = (),
+    env: Optional[Mapping[str, str]] = None,
+    secrets: tuple[str, ...] | list[str] = (),
+    python_version: Optional[str] = None,
+) -> Callable[[Callable[..., Any]], UdfDefinition]: ...
+
+
+def udf(
+    function: Optional[Callable[..., Any]] = None,
+    *,
+    name: Optional[str] = None,
+    input_schema: Optional[pa.Schema] = None,
+    output_schema: Optional[pa.DataType | pa.Field | pa.Schema] = None,
+    pip: tuple[str, ...] | list[str] = (),
+    env: Optional[Mapping[str, str]] = None,
+    secrets: tuple[str, ...] | list[str] = (),
+    python_version: Optional[str] = None,
+):
+    """Prepare a scalar Python callable for remote Function registration.
+
+    Input and output signatures are inferred from supported annotations. For
+    Arrow types annotations cannot express precisely, pass ``input_schema``
+    and ``output_schema`` together. Nullable outputs are rejected because V1
+    uses physical NULL to represent unassigned computed-column rows.
+
+    Parameters
+    ----------
+    function : Callable, optional
+        The synchronous scalar callable to package.
+    name : str, optional
+        The remote Function name. Defaults to the callable name.
+    input_schema : pyarrow.Schema, optional
+        Explicit input fields in the exact order of the callable parameters.
+        Must be provided together with ``output_schema``.
+    output_schema : pyarrow.DataType, pyarrow.Field, or pyarrow.Schema, optional
+        Explicit scalar or named-struct output. Must be non-nullable and be
+        provided together with ``input_schema``.
+    pip : sequence of str, optional
+        Pip requirements for the remote environment.
+    env : mapping of str to str, optional
+        Non-secret environment variables. Use ``secrets`` for credentials.
+    secrets : sequence of str, optional
+        Names of secrets resolved by the remote service. Secret values are not
+        accepted by this API or included in the registration request.
+    python_version : str, optional
+        Remote Python major/minor version. Defaults to the client version.
+
+    Returns
+    -------
+    UdfDefinition
+        A callable definition accepted by
+        :meth:`lancedb.db.DBConnection.create_function`,
+        :meth:`lancedb.db.AsyncConnection.create_function_async` and
+        :meth:`lancedb.db.DBConnection.create_function_async`.
+
+    Examples
+    --------
+    >>> from lancedb import udf
+    >>> @udf(pip=["numpy==2.2.0"], secrets=["MODEL_TOKEN"])
+    ... def score(value: float) -> float:
+    ...     return value * 2
+    >>> score(1.5)
+    3.0
+    """
+
+    def decorate(target: Callable[..., Any]) -> UdfDefinition:
+        return UdfDefinition(
+            target,
+            name=name,
+            input_schema=input_schema,
+            output_schema=output_schema,
+            pip=tuple(pip),
+            env={} if env is None else env,
+            secrets=tuple(secrets),
+            python_version=python_version,
+        )
+
+    if function is None:
+        return decorate
+    return decorate(function)
+
+
 __all__ = [
     "ApplicationInput",
     "FunctionApplication",
     "FunctionArtifact",
+    "FunctionArtifactContent",
+    "FunctionArtifactRequest",
     "FunctionBinding",
     "FunctionOutput",
     "FunctionParameter",
+    "FunctionRegistrationRequest",
     "FunctionResultField",
     "FunctionSignature",
     "FunctionVersion",
@@ -375,6 +903,9 @@ __all__ = [
     "InputBinding",
     "OutputMapping",
     "PythonEnvironmentSpec",
+    "PythonAdapterSpec",
     "PythonRuntimeSpec",
     "RefreshColumnResult",
+    "UdfDefinition",
+    "udf",
 ]

python/python/lancedb/job.py

@@ -5,20 +5,23 @@
 
 import asyncio
 from datetime import timedelta
-from typing import Optional
+from typing import Any, Generic, Optional, TypeVar, cast
 
 from lancedb.background_loop import LOOP
 
 from . import _lancedb
+from .functions import FunctionVersion
+
+T = TypeVar("T")
 
 
-class AsyncJob:
+class AsyncJob(Generic[T]):
     """A handle to an operation that may still be running.
 
     The operation may already be complete when the handle is created.
     """
 
-    def __init__(self, inner: Optional["_lancedb.Job"]):
+    def __init__(self, inner: Optional[Any]):
         self._inner = inner
 
     @property
@@ -44,18 +47,20 @@ class AsyncJob:
             return "finished"
         return await self._inner.status()
 
-    async def wait(self, timeout: Optional[timedelta] = None):
+    async def wait(self, timeout: Optional[timedelta] = None) -> T:
         """Wait until the operation reaches a terminal state.
 
         Raises `JobFailedError` if the operation failed, `JobCancelledError`
         if it was cancelled, and `TimeoutError` if `timeout` elapses first.
         """
         if self._inner is None:
-            return
+            return cast(T, None)
         if timeout is None:
-            await self._inner.wait()
-        else:
-            await asyncio.wait_for(self._inner.wait(), timeout.total_seconds())
+            return cast(T, await self._inner.wait())
+        return cast(
+            T,
+            await asyncio.wait_for(self._inner.wait(), timeout.total_seconds()),
+        )
 
     async def cancel(self):
         """Request cancellation. Cancelling a finished operation is a no-op."""
@@ -64,10 +69,10 @@ class AsyncJob:
         await self._inner.cancel()
 
 
-class Job:
+class Job(Generic[T]):
     """Synchronous counterpart of `AsyncJob`."""
 
-    def __init__(self, inner: Optional[AsyncJob]):
+    def __init__(self, inner: Optional[AsyncJob[T]]):
         self._inner = inner
 
     @property
@@ -88,18 +93,40 @@ class Job:
             return "finished"
         return LOOP.run(self._inner.status())
 
-    def wait(self, timeout: Optional[timedelta] = None):
+    def wait(self, timeout: Optional[timedelta] = None) -> T:
         """Block until the operation reaches a terminal state.
 
         Raises `JobFailedError` if the operation failed, `JobCancelledError`
         if it was cancelled, and `TimeoutError` if `timeout` elapses first.
         """
         if self._inner is None:
-            return
-        LOOP.run(self._inner.wait(timeout))
+            return cast(T, None)
+        return LOOP.run(self._inner.wait(timeout))
 
     def cancel(self):
         """Request cancellation. Cancelling a finished operation is a no-op."""
         if self._inner is None:
             return
         LOOP.run(self._inner.cancel())
+
+
+class _FunctionJobAdapter:
+    def __init__(self, inner: "_lancedb.FunctionJob"):
+        self._inner = inner
+
+    @property
+    def id(self) -> Optional[str]:
+        return self._inner.id
+
+    async def status(self) -> str:
+        return await self._inner.status()
+
+    async def wait(self) -> FunctionVersion:
+        return FunctionVersion.from_json(await self._inner.wait())
+
+    async def cancel(self):
+        await self._inner.cancel()
+
+
+def _function_job(inner: "_lancedb.FunctionJob") -> AsyncJob[FunctionVersion]:
+    return AsyncJob(_FunctionJobAdapter(inner))

python/python/lancedb/remote/db.py

@@ -23,6 +23,7 @@ import pyarrow as pa
 
 from ..common import DATA
 from ..db import DBConnection, LOOP
+from ..functions import FunctionVersion, UdfDefinition
 from ..job import AsyncJob, Job
 
 if TYPE_CHECKING:
@@ -713,6 +714,14 @@ class RemoteDBConnection(DBConnection):
         """
         return Job(self._conn.job(job_id))
 
+    @override
+    def create_function_async(self, definition: UdfDefinition) -> Job[FunctionVersion]:
+        return Job(LOOP.run(self._conn.create_function_async(definition)))
+
+    @override
+    def get_function(self, name: str, *, version: str) -> FunctionVersion:
+        return LOOP.run(self._conn.get_function(name, version=version))
+
     @override
     def list_jobs(self) -> List["JobInfo"]:
         """List server-side jobs across the database's tables."""

python/python/tests/test_first_class_function_slice2.py

@@ -0,0 +1,254 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright The LanceDB Authors
+
+from __future__ import annotations
+
+import contextlib
+import http.server
+import json
+from pathlib import Path
+import threading
+from typing import Optional
+
+import pyarrow as pa
+import pytest
+
+import lancedb
+from lancedb.functions import UdfDefinition, udf
+
+
+FIXTURES = (
+    Path(__file__).parents[3]
+    / "rust"
+    / "lancedb"
+    / "tests"
+    / "fixtures"
+    / "first_class_functions"
+    / "v1"
+)
+
+
+@udf(
+    pip=["numpy>=2"],
+    env={"MODE": "test"},
+    secrets=["API_TOKEN"],
+    python_version="3.12",
+)
+def normalize_score(value: float) -> float:
+    return value / 100.0
+
+
+def _assert_no_secret_values(value):
+    if isinstance(value, dict):
+        for key, child in value.items():
+            assert key not in {
+                "secret_value",
+                "secret_values",
+                "resolved_secret",
+                "resolved_secrets",
+            }
+            _assert_no_secret_values(child)
+    elif isinstance(value, list):
+        for child in value:
+            _assert_no_secret_values(child)
+
+
+def test_scalar_udf_matches_shared_registration_golden_and_remains_callable():
+    assert isinstance(normalize_score, UdfDefinition)
+    assert normalize_score(25.0) == 0.25
+    assert (
+        normalize_score.registration_request.to_canonical_json()
+        == (FIXTURES / "remote_function_registration_request.canonical.json")
+        .read_text()
+        .strip()
+    )
+    request = json.loads(normalize_score.registration_request.to_canonical_json())
+    assert request["artifact"]["adapter"] == {
+        "kind": "scalar_to_arrow_batch",
+        "version": 1,
+    }
+    assert request["required_secrets"] == ["API_TOKEN"]
+    _assert_no_secret_values(request)
+
+
+def test_explicit_arrow_schema_is_deterministic():
+    input_schema = pa.schema([pa.field("value", pa.float32(), nullable=True)])
+    output_schema = pa.field("embedding", pa.list_(pa.float32(), 3), nullable=False)
+
+    @udf(input_schema=input_schema, output_schema=output_schema)
+    def explicit(value):
+        return [value, value, value]
+
+    signature = explicit.registration_request.signature
+    assert signature.inputs[0].arrow_type == "float32"
+    assert signature.inputs[0].nullable is True
+    assert signature.output.arrow_type == "fixed_size_list<float32>[3]"
+    assert signature.output.nullable is False
+
+
+def test_annotation_and_explicit_schema_validation_fail_closed():
+    with pytest.raises(TypeError, match="missing Function annotations"):
+
+        @udf
+        def missing(value):
+            return value
+
+    with pytest.raises(TypeError, match="unsupported Function annotation"):
+
+        @udf
+        def unsupported(value: set[str]) -> str:
+            return ""
+
+    with pytest.raises(ValueError, match="output must be non-nullable"):
+
+        @udf
+        def nullable_output(value: int) -> Optional[int]:
+            return value
+
+    with pytest.raises(ValueError, match="provided together"):
+
+        @udf(input_schema=pa.schema([pa.field("value", pa.int64())]))
+        def partial_schema(value):
+            return value
+
+    with pytest.raises(ValueError, match="exactly match callable parameters"):
+
+        @udf(
+            input_schema=pa.schema([pa.field("other", pa.int64())]),
+            output_schema=pa.int64(),
+        )
+        def wrong_name(value):
+            return value
+
+    with pytest.raises(ValueError, match="output must be non-nullable"):
+
+        @udf(
+            input_schema=pa.schema([pa.field("value", pa.int64())]),
+            output_schema=pa.field("result", pa.int64(), nullable=True),
+        )
+        def nullable_explicit(value):
+            return value
+
+
+def test_environment_rejects_secret_value_overlap():
+    with pytest.raises(ValueError, match="must be disjoint"):
+
+        @udf(env={"TOKEN": "plaintext"}, secrets=["TOKEN"])
+        def overlapping(value: int) -> int:
+            return value
+
+
+def test_local_function_catalog_operations_are_not_supported(tmp_path):
+    db = lancedb.connect(tmp_path)
+    message = "Function catalog operations are not supported by this database"
+    with pytest.raises(NotImplementedError, match=message):
+        db.create_function(normalize_score)
+    with pytest.raises(NotImplementedError, match=message):
+        db.create_function_async(normalize_score)
+    with pytest.raises(NotImplementedError, match=message):
+        db.get_function("normalize_score", version="fv_exact")
+
+
+@contextlib.contextmanager
+def _mock_remote_function_catalog():
+    state = {"requests": [], "version": None}
+
+    class Handler(http.server.BaseHTTPRequestHandler):
+        def log_message(self, *args):
+            pass
+
+        def do_POST(self):
+            length = int(self.headers.get("Content-Length", "0"))
+            body = json.loads(self.rfile.read(length) or b"{}")
+            state["requests"].append((self.path, body))
+            status = 200
+            if self.path == "/v1/function/create":
+                state["version"] = {
+                    "name": body["name"],
+                    "version": "fv_exact",
+                    "artifact": {
+                        key: body["artifact"][key]
+                        for key in ("kind", "digest", "entrypoint")
+                    },
+                    "signature": body["signature"],
+                    "runtime": body["runtime"],
+                    "runtime_digest": "sha256:runtime",
+                    "environment_digest": "sha256:environment",
+                    "required_secrets": body.get("required_secrets", []),
+                    "created_at": "2026-08-21T00:00:00Z",
+                }
+                response = {"job_id": "job-register"}
+                status = 202
+            elif self.path == "/v1/jobs/describe":
+                assert body == {"job_id": "job-register"}
+                response = {
+                    "job_id": "job-register",
+                    "job_type": "create_function",
+                    "job_state": "DONE",
+                    "result": state["version"],
+                }
+            elif self.path == "/v1/function/describe":
+                assert body == {
+                    "name": "normalize_score",
+                    "version": "fv_exact",
+                }
+                response = state["version"]
+            else:
+                status = 404
+                response = {"error": "not found"}
+            encoded = json.dumps(response).encode()
+            self.send_response(status)
+            self.send_header("Content-Type", "application/json")
+            self.send_header("Content-Length", str(len(encoded)))
+            self.end_headers()
+            self.wfile.write(encoded)
+
+    with http.server.HTTPServer(("localhost", 0), Handler) as server:
+        thread = threading.Thread(target=server.serve_forever)
+        thread.start()
+        try:
+            yield f"http://localhost:{server.server_address[1]}", state
+        finally:
+            server.shutdown()
+            thread.join()
+
+
+def test_remote_registration_job_and_exact_version_reopen_round_trip():
+    with _mock_remote_function_catalog() as (host, state):
+        db = lancedb.connect(
+            "db://dev",
+            api_key="fake",
+            host_override=host,
+            client_config={"retry_config": {"retries": 0}},
+        )
+        registration = db.create_function_async(normalize_score)
+        assert registration.id == "job-register"
+        created = registration.wait()
+        reopened = db.get_function("normalize_score", version=created.version)
+
+    assert created == reopened
+    assert reopened.name == "normalize_score"
+    assert reopened.version == "fv_exact"
+    create_request = state["requests"][0][1]
+    assert create_request == json.loads(
+        normalize_score.registration_request.to_canonical_json()
+    )
+    _assert_no_secret_values(create_request)
+
+
+def test_blocking_remote_registration_returns_function_version():
+    with _mock_remote_function_catalog() as (host, state):
+        db = lancedb.connect(
+            "db://dev",
+            api_key="fake",
+            host_override=host,
+            client_config={"retry_config": {"retries": 0}},
+        )
+        created = db.create_function(normalize_score)
+
+    assert created.name == "normalize_score"
+    assert created.version == "fv_exact"
+    assert [path for path, _ in state["requests"]] == [
+        "/v1/function/create",
+        "/v1/jobs/describe",
+    ]

python/src/connection.rs

@@ -563,6 +563,38 @@ impl Connection {
         Ok(crate::job::Job::new(inner.job(job_id).infer_error()?))
     }
 
+    pub fn create_function_async(
+        self_: PyRef<'_, Self>,
+        request_json: String,
+    ) -> PyResult<Bound<'_, PyAny>> {
+        let inner = self_.get_inner()?.clone();
+        let request = lancedb::function::FunctionRegistrationRequest::from_json(&request_json)
+            .infer_error()?;
+        future_into_py(self_.py(), async move {
+            inner
+                .create_function_async(request)
+                .await
+                .infer_error()
+                .map(crate::job::FunctionJob::new)
+        })
+    }
+
+    pub fn get_function(
+        self_: PyRef<'_, Self>,
+        name: String,
+        version: String,
+    ) -> PyResult<Bound<'_, PyAny>> {
+        let inner = self_.get_inner()?.clone();
+        future_into_py(self_.py(), async move {
+            inner
+                .get_function(name, version)
+                .await
+                .infer_error()?
+                .to_canonical_json()
+                .infer_error()
+        })
+    }
+
     pub fn list_jobs(self_: PyRef<'_, Self>) -> PyResult<Bound<'_, PyAny>> {
         let inner = self_.get_inner()?.clone();
         future_into_py(self_.py(), async move {

python/src/job.rs

@@ -13,6 +13,23 @@ pub struct Job {
     inner: Arc<lancedb::Job>,
 }
 
+/// Python bridge for a typed remote Function registration job.
+///
+/// The public Python layer decodes the canonical JSON returned by `wait`
+/// into its immutable `FunctionVersion` model.
+#[pyclass]
+pub struct FunctionJob {
+    inner: Arc<lancedb::Job<lancedb::function::FunctionVersion>>,
+}
+
+impl FunctionJob {
+    pub(crate) fn new(inner: lancedb::Job<lancedb::function::FunctionVersion>) -> Self {
+        Self {
+            inner: Arc::new(inner),
+        }
+    }
+}
+
 impl Job {
     pub(crate) fn new(inner: lancedb::Job) -> Self {
         Self {
@@ -21,6 +38,42 @@ impl Job {
     }
 }
 
+#[pymethods]
+impl FunctionJob {
+    #[getter]
+    pub fn id(&self) -> Option<String> {
+        self.inner.id().map(str::to_string)
+    }
+
+    pub fn status(self_: PyRef<'_, Self>) -> PyResult<Bound<'_, PyAny>> {
+        let inner = self_.inner.clone();
+        future_into_py(
+            self_.py(),
+            async move { inner.status().await.infer_error() },
+        )
+    }
+
+    pub fn wait(self_: PyRef<'_, Self>) -> PyResult<Bound<'_, PyAny>> {
+        let inner = self_.inner.clone();
+        future_into_py(self_.py(), async move {
+            inner
+                .wait()
+                .await
+                .infer_error()?
+                .to_canonical_json()
+                .infer_error()
+        })
+    }
+
+    pub fn cancel(self_: PyRef<'_, Self>) -> PyResult<Bound<'_, PyAny>> {
+        let inner = self_.inner.clone();
+        future_into_py(self_.py(), async move {
+            inner.cancel().await.infer_error()?;
+            Ok(())
+        })
+    }
+}
+
 #[pymethods]
 impl Job {
     #[getter]

python/src/lib.rs

@@ -47,6 +47,7 @@ pub fn _lancedb(_py: Python, m: &Bound<'_, PyModule>) -> PyResult<()> {
     m.add_class::<Session>()?;
     m.add_class::<Table>()?;
     m.add_class::<crate::job::Job>()?;
+    m.add_class::<crate::job::FunctionJob>()?;
     m.add_class::<crate::job::JobInfo>()?;
     m.add_class::<crate::job::JobDescription>()?;
     m.add_class::<crate::job::JobFailureInfo>()?;

rust/lancedb/src/connection.rs

@@ -496,6 +496,33 @@ impl Connection {
         )
     }
 
+    /// Register a Python callable as a new immutable Function version.
+    ///
+    /// Registration is remote-only and always asynchronous. Waiting on the
+    /// returned typed job yields the durable [`crate::function::FunctionVersion`].
+    /// Local databases return [`Error::NotSupported`].
+    pub async fn create_function_async(
+        &self,
+        request: crate::function::FunctionRegistrationRequest,
+    ) -> Result<crate::job::Job<crate::function::FunctionVersion>> {
+        self.internal.create_function_async(request).await
+    }
+
+    /// Look up one exact immutable Function version in the remote catalog.
+    ///
+    /// Both the logical name and server-assigned version id are required;
+    /// mutable aliases and latest-version lookup are intentionally absent.
+    /// Local databases return [`Error::NotSupported`].
+    pub async fn get_function(
+        &self,
+        name: impl AsRef<str>,
+        version: impl AsRef<str>,
+    ) -> Result<crate::function::FunctionVersion> {
+        self.internal
+            .get_function(name.as_ref(), version.as_ref())
+            .await
+    }
+
     /// Rename a table in the database.
     ///
     /// This is only supported in LanceDB Cloud.

rust/lancedb/src/database.rs

@@ -241,6 +241,12 @@ fn job_op_not_supported<T>(what: &str) -> Result<T> {
     })
 }
 
+fn function_catalog_not_supported<T>() -> Result<T> {
+    Err(crate::error::Error::NotSupported {
+        message: "Function catalog operations are not supported by this database".to_string(),
+    })
+}
+
 /// The `Database` trait defines the interface for database implementations.
 ///
 /// A database is responsible for managing tables and their metadata.
@@ -286,6 +292,21 @@ pub trait Database:
     ///
     /// See [`CloneTableRequest`] for detailed documentation and examples.
     async fn clone_table(&self, request: CloneTableRequest) -> Result<Arc<dyn BaseTable>>;
+    /// Register an immutable Function version through the remote catalog.
+    async fn create_function_async(
+        &self,
+        _request: crate::function::FunctionRegistrationRequest,
+    ) -> Result<crate::job::Job<crate::function::FunctionVersion>> {
+        function_catalog_not_supported()
+    }
+    /// Look up one exact immutable Function version.
+    async fn get_function(
+        &self,
+        _name: &str,
+        _version: &str,
+    ) -> Result<crate::function::FunctionVersion> {
+        function_catalog_not_supported()
+    }
     /// A [`crate::job::Job`] handle for a server-side job by id, suitable for
     /// waiting on or cancelling the job. The handle is constructed without a
     /// server round trip; an unknown id surfaces when the handle is used.

rust/lancedb/src/function.rs

@@ -369,6 +369,56 @@ impl FunctionVersion {
 
 impl_json!(FunctionVersion);
 
+/// Encoded artifact bytes uploaded with a Function registration request.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct FunctionArtifactContent {
+    /// Encoding of `data`. V1 Python authoring uses `base64`.
+    pub encoding: String,
+    pub data: String,
+}
+
+/// Internal execution adapter selected for a Python callable artifact.
+///
+/// The adapter converts the public scalar callable to the Arrow batch ABI
+/// used by the remote executor. It is part of the request envelope, not a
+/// public batch-UDF authoring mode.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PythonAdapterSpec {
+    pub kind: String,
+    pub version: u32,
+}
+
+/// Python artifact uploaded while registering a Function.
+///
+/// Unlike [`FunctionArtifact`], which is the durable artifact identity
+/// returned by the catalog, this request value contains the encoded source
+/// bytes that Sophon must durably bake before publishing a FunctionVersion.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct FunctionArtifactRequest {
+    pub kind: String,
+    pub digest: String,
+    pub entrypoint: String,
+    pub content: FunctionArtifactContent,
+    pub adapter: PythonAdapterSpec,
+}
+
+/// Stable request envelope for remote immutable Function registration.
+///
+/// Secret values deliberately have no field in this model. The only secret
+/// material the client may send is the ordered set of names Sophon resolves
+/// inside the remote runtime.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct FunctionRegistrationRequest {
+    pub name: String,
+    pub artifact: FunctionArtifactRequest,
+    pub signature: FunctionSignature,
+    pub runtime: PythonRuntimeSpec,
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub required_secrets: Vec<String>,
+}
+
+impl_json!(FunctionRegistrationRequest);
+
 /// Exact FunctionVersion reference embedded in applications and bindings.
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 pub struct FunctionVersionRef {

rust/lancedb/src/job.rs

@@ -126,8 +126,7 @@ impl<T> Job<T>
 where
     T: Clone + DeserializeOwned + Send + Sync + 'static,
 {
-    /// Construct a typed remote Job before result-specific submit APIs are added.
-    #[allow(dead_code)]
+    /// Construct a typed remote Job for a result-specific submit API.
     pub(crate) fn new_typed(handle: Box<dyn JobHandle>) -> Self {
         Self {
             inner: JobInner::Handle {

rust/lancedb/src/remote/db.rs

@@ -24,6 +24,7 @@ use crate::database::{
     JobDescription, JobInfo, OpenTableRequest, ReadConsistency, TableNamesRequest,
 };
 use crate::error::Result;
+use crate::function::{FunctionRegistrationRequest, FunctionVersion};
 use crate::job::Job;
 use crate::remote::job::{DescribeJobResponse, RemoteJob, job_state_to_client};
 use crate::remote::util::stream_as_body;
@@ -489,6 +490,39 @@ impl<S: HttpSend> Database for RemoteDatabase<S> {
         })
     }
 
+    async fn create_function_async(
+        &self,
+        request: FunctionRegistrationRequest,
+    ) -> Result<Job<FunctionVersion>> {
+        let req = self.client.post("/v1/function/create").json(&request);
+        let (request_id, response) = self.client.send(req).await?;
+        let response = self.client.check_response(&request_id, response).await?;
+        let status = response.status();
+        let body = response.text().await.err_to_http(request_id.clone())?;
+        let job_id = extract_job_id(&body).ok_or_else(|| Error::Http {
+            source: "Function registration response did not contain a valid job_id".into(),
+            request_id,
+            status_code: Some(status),
+        })?;
+        Ok(Job::new_typed(Box::new(RemoteJob::new(
+            self.client.clone(),
+            job_id,
+        ))))
+    }
+
+    async fn get_function(&self, name: &str, version: &str) -> Result<FunctionVersion> {
+        let req = self
+            .client
+            .post("/v1/function/describe")
+            .json(&serde_json::json!({
+                "name": name,
+                "version": version,
+            }));
+        let (request_id, response) = self.client.send(req).await?;
+        let response = self.client.check_response(&request_id, response).await?;
+        response.json().await.err_to_http(request_id)
+    }
+
     fn job(&self, job_id: &str) -> Result<crate::job::Job> {
         Ok(crate::job::Job::new(Box::new(super::job::RemoteJob::new(
             self.client.clone(),
@@ -2446,6 +2480,60 @@ mod tests {
         assert_eq!(batches[0].num_rows(), 2);
     }
 
+    #[tokio::test]
+    async fn test_create_function_async_sends_canonical_request_and_decodes_typed_job() {
+        const REQUEST: &str = include_str!(
+            "../../tests/fixtures/first_class_functions/v1/remote_function_registration_request.json"
+        );
+        const FUNCTION_JOB: &str =
+            include_str!("../../tests/fixtures/first_class_functions/v1/remote_function_job.json");
+        let expected: serde_json::Value = serde_json::from_str(REQUEST).unwrap();
+        let conn = Connection::new_with_handler(move |request| match request.url().path() {
+            "/v1/function/create" => {
+                assert_eq!(request.method(), &reqwest::Method::POST);
+                let body: serde_json::Value =
+                    serde_json::from_slice(request.body().unwrap().as_bytes().unwrap()).unwrap();
+                assert_eq!(body, expected);
+                http::Response::builder()
+                    .status(202)
+                    .body(r#"{"job_id":"job-function-1"}"#)
+                    .unwrap()
+            }
+            "/v1/jobs/describe" => http::Response::builder()
+                .status(200)
+                .body(FUNCTION_JOB)
+                .unwrap(),
+            path => panic!("unexpected path: {path}"),
+        });
+        let request = crate::function::FunctionRegistrationRequest::from_json(REQUEST).unwrap();
+        let job = conn.create_function_async(request).await.unwrap();
+        assert_eq!(job.id(), Some("job-function-1"));
+        let version = job.wait().await.unwrap();
+        assert_eq!(version.name(), "embed");
+        assert_eq!(version.version(), "fv_01K3EXACT");
+    }
+
+    #[tokio::test]
+    async fn test_get_function_requires_and_sends_exact_version() {
+        const VERSION: &str = include_str!(
+            "../../tests/fixtures/first_class_functions/v1/remote_function_version.canonical.json"
+        );
+        let conn = Connection::new_with_handler(|request| {
+            assert_eq!(request.method(), &reqwest::Method::POST);
+            assert_eq!(request.url().path(), "/v1/function/describe");
+            let body: serde_json::Value =
+                serde_json::from_slice(request.body().unwrap().as_bytes().unwrap()).unwrap();
+            assert_eq!(
+                body,
+                serde_json::json!({"name": "embed", "version": "fv_01K3EXACT"})
+            );
+            http::Response::builder().status(200).body(VERSION).unwrap()
+        });
+        let version = conn.get_function("embed", "fv_01K3EXACT").await.unwrap();
+        assert_eq!(version.name(), "embed");
+        assert_eq!(version.version(), "fv_01K3EXACT");
+    }
+
     #[tokio::test]
     async fn test_conn_job_waits_to_done() {
         let polls = Arc::new(AtomicUsize::new(0));

rust/lancedb/tests/first_class_function_slice2.rs

@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: Copyright The LanceDB Authors
+
+use std::fs;
+use std::path::PathBuf;
+
+use lancedb::Error;
+use lancedb::function::FunctionRegistrationRequest;
+use serde_json::Value;
+
+fn fixture(name: &str) -> String {
+    let path = PathBuf::from(env!("CARGO_MANIFEST_DIR"))
+        .join("tests/fixtures/first_class_functions/v1")
+        .join(name);
+    fs::read_to_string(path).expect("fixture must be readable")
+}
+
+fn assert_no_secret_values(value: &Value) {
+    match value {
+        Value::Object(values) => {
+            for (key, value) in values {
+                assert!(
+                    !matches!(
+                        key.as_str(),
+                        "secret_value" | "secret_values" | "resolved_secret" | "resolved_secrets"
+                    ),
+                    "registration requests must not model resolved secret material"
+                );
+                assert_no_secret_values(value);
+            }
+        }
+        Value::Array(values) => values.iter().for_each(assert_no_secret_values),
+        _ => {}
+    }
+}
+
+#[test]
+fn registration_request_matches_shared_canonical_golden() {
+    let request = FunctionRegistrationRequest::from_json(&fixture(
+        "remote_function_registration_request.json",
+    ))
+    .expect("registration request");
+    assert_eq!(request.name, "normalize_score");
+    assert_eq!(request.artifact.adapter.kind, "scalar_to_arrow_batch");
+    assert_eq!(request.required_secrets, ["API_TOKEN"]);
+    assert_eq!(
+        request.to_canonical_json().expect("canonical request"),
+        fixture("remote_function_registration_request.canonical.json").trim()
+    );
+
+    let value: Value =
+        serde_json::from_str(&request.to_canonical_json().expect("canonical request"))
+            .expect("request JSON");
+    assert_no_secret_values(&value);
+}
+
+#[tokio::test]
+async fn local_function_catalog_operations_return_stable_not_supported() {
+    let directory = tempfile::tempdir().unwrap();
+    let connection = lancedb::connect(directory.path().to_str().unwrap())
+        .execute()
+        .await
+        .unwrap();
+    let request = FunctionRegistrationRequest::from_json(&fixture(
+        "remote_function_registration_request.json",
+    ))
+    .unwrap();
+
+    let create_error = connection.create_function_async(request).await.unwrap_err();
+    let lookup_error = connection
+        .get_function("normalize_score", "fv_exact")
+        .await
+        .unwrap_err();
+    for error in [create_error, lookup_error] {
+        assert!(matches!(
+            error,
+            Error::NotSupported { message }
+                if message == "Function catalog operations are not supported by this database"
+        ));
+    }
+}

rust/lancedb/tests/fixtures/first_class_functions/v1/remote_function_registration_request.canonical.json

@@ -0,0 +1 @@
+{"artifact":{"adapter":{"kind":"scalar_to_arrow_batch","version":1},"content":{"data":"ZnJvbSBfX2Z1dHVyZV9fIGltcG9ydCBhbm5vdGF0aW9ucwoKZGVmIG5vcm1hbGl6ZV9zY29yZSh2YWx1ZTogZmxvYXQpIC0+IGZsb2F0OgogICAgcmV0dXJuIHZhbHVlIC8gMTAwLjAK","encoding":"base64"},"digest":"sha256:760784bdcef57b802f389b97804cc0b618aae39e86044733451bcd0b13089a7f","entrypoint":"normalize_score","kind":"python_callable"},"name":"normalize_score","required_secrets":["API_TOKEN"],"runtime":{"env":{"MODE":"test"},"environment":{"kind":"pip","packages":["numpy>=2"]},"kind":"python","python_version":"3.12"},"signature":{"inputs":[{"arrow_type":"float64","name":"value","nullable":false}],"output":{"arrow_type":"float64","kind":"scalar","nullable":false}}}

rust/lancedb/tests/fixtures/first_class_functions/v1/remote_function_registration_request.json

@@ -0,0 +1,46 @@
+{
+  "name": "normalize_score",
+  "artifact": {
+    "kind": "python_callable",
+    "digest": "sha256:760784bdcef57b802f389b97804cc0b618aae39e86044733451bcd0b13089a7f",
+    "entrypoint": "normalize_score",
+    "content": {
+      "encoding": "base64",
+      "data": "ZnJvbSBfX2Z1dHVyZV9fIGltcG9ydCBhbm5vdGF0aW9ucwoKZGVmIG5vcm1hbGl6ZV9zY29yZSh2YWx1ZTogZmxvYXQpIC0+IGZsb2F0OgogICAgcmV0dXJuIHZhbHVlIC8gMTAwLjAK"
+    },
+    "adapter": {
+      "kind": "scalar_to_arrow_batch",
+      "version": 1
+    }
+  },
+  "signature": {
+    "inputs": [
+      {
+        "name": "value",
+        "arrow_type": "float64",
+        "nullable": false
+      }
+    ],
+    "output": {
+      "kind": "scalar",
+      "arrow_type": "float64",
+      "nullable": false
+    }
+  },
+  "runtime": {
+    "kind": "python",
+    "python_version": "3.12",
+    "environment": {
+      "kind": "pip",
+      "packages": [
+        "numpy>=2"
+      ]
+    },
+    "env": {
+      "MODE": "test"
+    }
+  },
+  "required_secrets": [
+    "API_TOKEN"
+  ]
+}