Enable nix-ld so uv-managed prebuilt binaries run on NixOS

uv fetches prebuilt CPython interpreters and native wheel extensions
that expect a standard glibc loader path, which doesn't exist on
NixOS without nix-ld. Enables it unconditionally on every NixOS host
and extends its library set with common CPython native-extension
dependencies not already covered by nix-ld's own defaults.

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

1 files changed, 23 insertions, 0 deletions

diff --git a/openspec/changes/archive/2026-09-24-enable-nix-ld/specs/dynamic-linking-support/spec.md b/openspec/changes/archive/2026-09-24-enable-nix-ld/specs/dynamic-linking-support/spec.md
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+## Purpose
+
+Lets NixOS hosts built from this flake run prebuilt, foreign (non-Nix-built) dynamically-linked binaries — such as the interpreters and native wheel extensions that developer tools like `uv` fetch at runtime — instead of failing with a missing-interpreter execution error.
+
+## ADDED Requirements
+
+### Requirement: NixOS hosts run foreign dynamically-linked binaries via nix-ld
+Every NixOS host built from this flake's shared system module SHALL enable `nix-ld`, so that prebuilt binaries linked against a standard (non-NixOS) dynamic loader path execute correctly instead of failing to run.
+
+#### Scenario: A uv-managed prebuilt Python interpreter executes
+- **WHEN** `uv python install` downloads a prebuilt CPython interpreter and that interpreter is invoked
+- **THEN** the interpreter starts successfully instead of failing with a missing-interpreter or "cannot execute binary file" error
+
+#### Scenario: A native wheel extension loads its shared library dependencies
+- **WHEN** a Python package installed by `uv` includes a prebuilt native (C-extension) binary that depends on common shared libraries (e.g. `ncurses`, `libffi`, `sqlite`, `readline`, `gdbm`, `expat`, or another library covered by `nix-ld`'s configured library set)
+- **THEN** the extension loads its dependencies successfully instead of failing with a missing shared library error
+
+### Requirement: The nix-ld library set is host-wide and additive
+The set of libraries made available to foreign binaries via `nix-ld` SHALL be defined once for all NixOS hosts built from this flake's shared system module, and SHALL be extensible by appending further libraries without removing or replacing the existing set.
+
+#### Scenario: A host-level addition does not remove existing libraries
+- **WHEN** a NixOS host's own configuration adds an additional library to the nix-ld library set
+- **THEN** the libraries already provided by the shared system module remain available, unaffected by the addition