Add the content tier: a standalone flake that auto-discovers each skill
(a directory containing a SKILL.md, at any depth) and exposes it as an
individually addressable derivation built by lib.mkSkill. Directories
without a SKILL.md are descended through as cosmetic containers; once a
SKILL.md is found, that directory's subfolders are its assets, not
further skills. Skill names must be globally unique across the tree — a
collision is a hard eval-time error, not a warning.

A fixture-driven skill-build check under `nix flake check` exercises the
recursive walk, the builder, the SKILL.md-at-$out-root contract, the
eval-time name passthru, and the collision error. The repo ships no real
skill content yet, so packages.<system> is empty today.

@@ -0,0 +2,4 @@
+#
+# Building this under `nix flake check` exercises the whole content tier at once.
+# The repo ships no real skill content, so the check drives fixture skills under
+# `./fixtures`, including a collision fixture that must fail discovery at eval.

@@ -0,0 +1,82 @@
+{
+  description = "Personal Claude Code agent skills, packaged through Nix.";

@@ -0,0 +3,4 @@
+
+  # Tracks unstable to match the maintainer's system.
+  # This input governs standalone builds and `nix flake check` only.
+  # A consumer deduplicates by pointing it at their own nixpkgs.

@@ -0,0 +18,4 @@
+        "aarch64-darwin"
+      ];
+
+      forAllSystems =

@@ -0,0 +35,4 @@
+
+      # Turns a skill source directory into a conforming derivation.
+      # Exposed as `lib.mkSkill` so a self-packaging tool repo can reuse the
+      # same contract.

@@ -0,0 +45,4 @@
+      # The skills this repo itself ships, empty today.
+      # A skill is added by creating `skills/<...>/<name>/SKILL.md`, and the walk
+      # finds it with no edit to this flake.
+      ownSkills = discoverSkills ./skills;

@@ -0,0 +2,4 @@
+#
+# Drives fixture skills through the whole content tier under `nix flake check`.
+# The fixtures pin every discovery shape and the collision hard-error
+# deterministically, independent of whichever real skills the repo carries.

@@ -0,0 +1,60 @@
+{
+  description = "Personal agent skills, packaged through Nix.";

@@ -0,0 +3,4 @@
+
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+
+  outputs =

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+      forAllSystems =
+        f:
+        nixpkgs.lib.genAttrs systems (
+          system:

@@ -0,0 +35,4 @@
+        nixpkgs.lib.listToAttrs (
+          map (skill: {
+            inherit (skill) name;
+            value = mkSkill { inherit pkgs; inherit (skill) name src; };

@@ -0,0 +45,4 @@
+      # No `default`: a catalog has no single default skill.
+      packages = forAllSystems ({ pkgs, ... }: skillPackages pkgs);
+
+      # Each discovered skill is folded in as its own check, so `nix flake check`

@@ -0,0 +18,4 @@
+          map (skill: {
+            inherit (skill) name;
+            value = mkSkill { inherit pkgs; inherit (skill) name src; };
+          }) discoveredSkills