fix(sdk): populate Author/Author-email via metadata hook

PEP 621 maps `authors` to PKG-INFO's `Author-email:` line but not to the
legacy single `Author:` line that `pip show` renders, and pip does
not display `Maintainer:` either. As a result every previous release
shipped with an empty `Author:` and the maintainer's name never
appeared in `pip show nullrun`.

Hatchling compounds this: its authors parser only adds an entry to
`authors_data["name"]` (which becomes `Author:`) when an
inline-table has a `name` and NO `email`. When both are present the
name is folded into `Author-email:`'s display_name and the legacy
`Author:` line is suppressed entirely.

Fix: declare `authors` and `maintainers` as dynamic fields and
populate them from a custom hatchling metadata hook
(`hatch_build.py`). The hook splits the primary author into a
name-only + email-only inline-table pair so hatchling populates both
`Author:` and `Author-email:`. Declaring at least one dynamic field
is what actually wires `MetadataHookInterface.update()` — without it
hatchling configures the hook but never invokes it.

Author: maltsev-dev

hatch_build.py

@@ -0,0 +1,51 @@
+"""Hatchling build hooks for the nullrun SDK.
+
+``authors`` / ``maintainers`` injection
+---------------------------------------
+PEP 621 maps the ``authors`` array to PKG-INFO's ``Author-email:``
+line but does NOT populate the legacy single ``Author:`` line, and
+``pip show`` only renders ``Author:`` (it does not render
+``Maintainer:`` at all). As a result a project whose ``authors`` is
+``[{name=..., email=...}]`` ships with an empty ``Author:`` field and
+the maintainer's name never appears in ``pip show``.
+
+Hatchling makes this worse: in its ``authors`` property parser
+(``hatchling/metadata/core.py``), an inline-table only contributes to
+the legacy ``Author:`` field when it has a ``name`` and NO ``email``.
+If both are set, the name is folded into the ``Author-email:``
+display_name and the ``Author:`` line is suppressed entirely.
+
+This hook splits the primary author into two inline-table entries so
+hatchling populates both ``authors_data["name"]`` (``Author:``) and
+``authors_data["email"]`` (``Author-email:``)::
+
+    Author: Anatolii Maltsev
+    Author-email: support@nullrun.io
+
+It also sets ``maintainers`` to the publishing org for the PyPI
+sidebar (pip does not display ``Maintainer:``).
+
+Why ``authors`` / ``maintainers`` are listed in ``project.dynamic``:
+hatchling only invokes ``MetadataHookInterface.update()`` when at
+least one field is marked dynamic. Removing the static arrays and
+keeping the hook as the single source of truth is what actually wires
+the update call.
+"""
+
+from __future__ import annotations
+
+from hatchling.metadata.plugin.interface import MetadataHookInterface
+
+
+class CustomMetadataHook(MetadataHookInterface):
+    PLUGIN_NAME = "custom"
+
+    def update(self, metadata: dict) -> None:
+        # See module docstring for the full rationale.
+        metadata["authors"] = [
+            {"name": "Anatolii Maltsev"},
+            {"email": "support@nullrun.io"},
+        ]
+        metadata["maintainers"] = [
+            {"name": "nullrun.io", "email": "support@nullrun.io"},
+        ]

pyproject.toml

@@ -14,18 +14,22 @@ readme = "README.md"
 license = { text = "Apache-2.0" }
 requires-python = ">=3.10"
 
-authors = [
-    { name = "nullrun.io", email = "support@nullrun.io" }
-]
-
-# Maintainer populates the PKG-INFO `Maintainer:` / `Maintainer-email:`
-# fields. PEP 621 maps the `authors` array to `Author-email:` but NOT
-# to the legacy `Author:` field, which leaves `pip show` displaying an
-# empty `Author:` line. Adding `maintainers` populates `Maintainer:`
-# instead so every metadata viewer shows non-empty contact info.
-maintainers = [
-    { name = "Anatolii Maltsev", email = "support@nullrun.io" }
-]
+# Authors and maintainers are populated dynamically by the custom
+# metadata hook in ``hatch_build.py``. Declaring ``authors`` here as a
+# dynamic field is what triggers hatchling to call
+# ``MetadataHookInterface.update()`` at all — without at least one
+# field in ``dynamic``, the hook is configured but never invoked.
+#
+# Why dynamic in the first place: PEP 621 maps the ``authors`` array to
+# PKG-INFO's ``Author-email:`` line but NOT to the legacy single
+# ``Author:`` line that ``pip show`` renders. Worse, hatchling's
+# authors parser (core.py, ``authors`` property) only populates the
+# legacy ``Author:`` field when an inline-table has a ``name`` and NO
+# ``email``; if both are present the name is folded into the email's
+# display_name and ``Author:`` is suppressed. The hook splits the
+# author into two inline-tables (name-only + email-only) so both lines
+# appear in the wheel METADATA.
+dynamic = ["authors", "maintainers"]
 
 keywords = [
     "circuit-breaker", "agent", "llm", "observability",
@@ -166,6 +170,15 @@ include = [
     "src/nullrun/py.typed",
 ]
 
+# Custom metadata hook: rewrites ``project.authors`` into name-only +
+# email-only inline tables so hatchling's authors parser populates both
+# the legacy ``Author:`` field and the ``Author-email:`` field. See
+# ``hatch_build.py`` for the full rationale. The hook lives at the repo
+# root because hatchling discovers it by import path, not via the wheel
+# ``packages`` list above (which only covers the runtime package).
+[tool.hatch.metadata.hooks.custom]
+path = "hatch_build.py"
+
 [tool.hatch.build.targets.sdist]
 exclude = [
     "tests/",