diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4566392..2196548 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,8 @@ Full release notes with details on each version: [GitHub Releases](https://githu
 
 ## Unreleased
 
+- Fix: the skill's Python-interpreter detection now accepts Homebrew `python@3.x` paths (#1586, thanks @SUDARSHANCHAUDHARI). The shebang allowlist rejected any path with a character outside `[a-zA-Z0-9/_.-]`, but Homebrew installs versioned Python under `python@3.13`, so a valid interpreter containing `@` was skipped and detection fell through to a bare `python3` that lacked graphify (every step then failed with `ModuleNotFoundError`). `@` is now allowed across all skill variants (matching the #473 hooks.py fix); injection characters are still rejected.
+- Fix: `graphify merge-graphs` no longer crashes on inputs that disagree on graph type (#1606, thanks @AdrianRusan). Per-repo `graph.json` files don't always share the same `directed` / `multigraph` flags, and `compose` requires one uniform type, so a mixed set raised an unhandled `NetworkXError`. All inputs are now normalized to a plain undirected graph (which the cross-repo merged view already is) before composing.
 - Fix: type-reference / inheritance edge gaps closed across seven languages (all thanks @Synvoya):
   - Scala: `var` field declarations now emit type `references` like `val` (#1587).
   - PowerShell: class base types after `:` now emit `inherits` (first) / `implements` (rest), matching the C# convention (#1588).
diff --git a/graphify/__main__.py b/graphify/__main__.py
index 736d7be..318f983 100644
--- a/graphify/__main__.py
+++ b/graphify/__main__.py
@@ -3912,7 +3912,14 @@ def main() -> None:
         # may be a MultiGraph and another a Graph.  Normalise everything to Graph
         # (the graphify default) by converting MultiGraphs with nx.Graph().
         def _to_simple(g: "_nx.Graph") -> "_nx.Graph":
-            if isinstance(g, _nx.MultiGraph):
+            # nx.compose requires every graph to be the same type. Inputs may
+            # disagree on BOTH axes — directed vs undirected, and multi vs simple
+            # — because per-repo graph.json files are written by different extract
+            # paths at different times. Normalise everything to a plain undirected
+            # Graph (the merged cross-repo view is undirected anyway), which covers
+            # DiGraph / MultiGraph / MultiDiGraph. Without this a directed input
+            # crashed compose with "All graphs must be directed or undirected" (#1606).
+            if type(g) is not _nx.Graph:
                 return _nx.Graph(g)
             return g
         merged = _nx.Graph()
diff --git a/graphify/skill-agents.md b/graphify/skill-agents.md
index 3735e8a..2e19931 100644
--- a/graphify/skill-agents.md
+++ b/graphify/skill-agents.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -626,7 +626,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/graphify/skill-aider.md b/graphify/skill-aider.md
index c79b7b8..2ccf532 100644
--- a/graphify/skill-aider.md
+++ b/graphify/skill-aider.md
@@ -71,7 +71,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
diff --git a/graphify/skill-amp.md b/graphify/skill-amp.md
index 3735e8a..2e19931 100644
--- a/graphify/skill-amp.md
+++ b/graphify/skill-amp.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -626,7 +626,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/graphify/skill-claw.md b/graphify/skill-claw.md
index 8ec9ad2..b354243 100644
--- a/graphify/skill-claw.md
+++ b/graphify/skill-claw.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -629,7 +629,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/graphify/skill-codex.md b/graphify/skill-codex.md
index 4a956e7..e6e411e 100644
--- a/graphify/skill-codex.md
+++ b/graphify/skill-codex.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -626,7 +626,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/graphify/skill-copilot.md b/graphify/skill-copilot.md
index 8ec9ad2..b354243 100644
--- a/graphify/skill-copilot.md
+++ b/graphify/skill-copilot.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -629,7 +629,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/graphify/skill-devin.md b/graphify/skill-devin.md
index 6bbbeaf..13fb37c 100644
--- a/graphify/skill-devin.md
+++ b/graphify/skill-devin.md
@@ -82,7 +82,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -865,7 +865,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/graphify/skill-droid.md b/graphify/skill-droid.md
index 480ef92..d1147b9 100644
--- a/graphify/skill-droid.md
+++ b/graphify/skill-droid.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -626,7 +626,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/graphify/skill-kilo.md b/graphify/skill-kilo.md
index df53e14..c455781 100644
--- a/graphify/skill-kilo.md
+++ b/graphify/skill-kilo.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -629,7 +629,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/graphify/skill-kiro.md b/graphify/skill-kiro.md
index 8ec9ad2..b354243 100644
--- a/graphify/skill-kiro.md
+++ b/graphify/skill-kiro.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -629,7 +629,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/graphify/skill-opencode.md b/graphify/skill-opencode.md
index b023ff8..684e0e2 100644
--- a/graphify/skill-opencode.md
+++ b/graphify/skill-opencode.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -621,7 +621,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/graphify/skill-pi.md b/graphify/skill-pi.md
index 8ec9ad2..b354243 100644
--- a/graphify/skill-pi.md
+++ b/graphify/skill-pi.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -629,7 +629,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/graphify/skill-trae.md b/graphify/skill-trae.md
index a643daa..ac16b92 100644
--- a/graphify/skill-trae.md
+++ b/graphify/skill-trae.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -627,7 +627,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/graphify/skill-vscode.md b/graphify/skill-vscode.md
index f0719bf..31a3352 100644
--- a/graphify/skill-vscode.md
+++ b/graphify/skill-vscode.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -625,7 +625,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/graphify/skill-windows.md b/graphify/skill-windows.md
index f6c83fb..6ab0e02 100644
--- a/graphify/skill-windows.md
+++ b/graphify/skill-windows.md
@@ -651,7 +651,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/graphify/skill.md b/graphify/skill.md
index 8ec9ad2..b354243 100644
--- a/graphify/skill.md
+++ b/graphify/skill.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -629,7 +629,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/tests/test_merge_graphs_cli.py b/tests/test_merge_graphs_cli.py
new file mode 100644
index 0000000..f3e0e05
--- /dev/null
+++ b/tests/test_merge_graphs_cli.py
@@ -0,0 +1,48 @@
+"""`graphify merge-graphs` tolerates inputs that disagree on graph type (#1606).
+
+Per-repo graph.json files written by different extract paths at different times
+don't always agree on the `directed` / `multigraph` flags. compose requires one
+uniform type, so a mixed set used to crash with an unhandled NetworkXError. The
+handler now normalizes every input to a plain undirected Graph before composing.
+"""
+from __future__ import annotations
+
+import json
+import subprocess
+import sys
+from pathlib import Path
+
+PYTHON = sys.executable
+
+
+def _run(args, cwd):
+    return subprocess.run([PYTHON, "-m", "graphify"] + args, cwd=cwd,
+                          capture_output=True, text=True)
+
+
+def _write(p: Path, directed: bool, multigraph: bool, node_id: str):
+    p.parent.mkdir(parents=True, exist_ok=True)
+    p.write_text(json.dumps({
+        "directed": directed, "multigraph": multigraph, "graph": {},
+        "nodes": [{"id": node_id}], "links": [],
+    }))
+
+
+def test_merge_graphs_mixed_directed_and_multigraph(tmp_path):
+    a = tmp_path / "r1" / "graphify-out" / "graph.json"
+    b = tmp_path / "r2" / "graphify-out" / "graph.json"
+    c = tmp_path / "r3" / "graphify-out" / "graph.json"
+    _write(a, directed=True, multigraph=False, node_id="x")    # DiGraph
+    _write(b, directed=False, multigraph=False, node_id="y")   # Graph
+    _write(c, directed=False, multigraph=True, node_id="z")    # MultiGraph
+    out = tmp_path / "merged.json"
+
+    r = _run(["merge-graphs", str(a), str(b), str(c), "--out", str(out)], tmp_path)
+    assert r.returncode == 0, f"merge crashed: {r.stderr}"
+    assert out.exists()
+    data = json.loads(out.read_text())
+    ids = {n["id"] for n in data["nodes"]}
+    # every input's node survives, normalized into one undirected simple graph
+    assert {"r1::x", "r2::y", "r3::z"} <= ids or len(ids) == 3
+    assert data.get("directed") is False
+    assert data.get("multigraph") is False
diff --git a/tools/skillgen/expected/graphify__skill-agents.md b/tools/skillgen/expected/graphify__skill-agents.md
index 3735e8a..2e19931 100644
--- a/tools/skillgen/expected/graphify__skill-agents.md
+++ b/tools/skillgen/expected/graphify__skill-agents.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -626,7 +626,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/tools/skillgen/expected/graphify__skill-aider.md b/tools/skillgen/expected/graphify__skill-aider.md
index c79b7b8..2ccf532 100644
--- a/tools/skillgen/expected/graphify__skill-aider.md
+++ b/tools/skillgen/expected/graphify__skill-aider.md
@@ -71,7 +71,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
diff --git a/tools/skillgen/expected/graphify__skill-amp.md b/tools/skillgen/expected/graphify__skill-amp.md
index 3735e8a..2e19931 100644
--- a/tools/skillgen/expected/graphify__skill-amp.md
+++ b/tools/skillgen/expected/graphify__skill-amp.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -626,7 +626,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/tools/skillgen/expected/graphify__skill-claw.md b/tools/skillgen/expected/graphify__skill-claw.md
index 8ec9ad2..b354243 100644
--- a/tools/skillgen/expected/graphify__skill-claw.md
+++ b/tools/skillgen/expected/graphify__skill-claw.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -629,7 +629,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/tools/skillgen/expected/graphify__skill-codex.md b/tools/skillgen/expected/graphify__skill-codex.md
index 4a956e7..e6e411e 100644
--- a/tools/skillgen/expected/graphify__skill-codex.md
+++ b/tools/skillgen/expected/graphify__skill-codex.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -626,7 +626,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/tools/skillgen/expected/graphify__skill-copilot.md b/tools/skillgen/expected/graphify__skill-copilot.md
index 8ec9ad2..b354243 100644
--- a/tools/skillgen/expected/graphify__skill-copilot.md
+++ b/tools/skillgen/expected/graphify__skill-copilot.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -629,7 +629,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/tools/skillgen/expected/graphify__skill-devin.md b/tools/skillgen/expected/graphify__skill-devin.md
index 6bbbeaf..13fb37c 100644
--- a/tools/skillgen/expected/graphify__skill-devin.md
+++ b/tools/skillgen/expected/graphify__skill-devin.md
@@ -82,7 +82,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -865,7 +865,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/tools/skillgen/expected/graphify__skill-droid.md b/tools/skillgen/expected/graphify__skill-droid.md
index 480ef92..d1147b9 100644
--- a/tools/skillgen/expected/graphify__skill-droid.md
+++ b/tools/skillgen/expected/graphify__skill-droid.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -626,7 +626,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/tools/skillgen/expected/graphify__skill-kilo.md b/tools/skillgen/expected/graphify__skill-kilo.md
index df53e14..c455781 100644
--- a/tools/skillgen/expected/graphify__skill-kilo.md
+++ b/tools/skillgen/expected/graphify__skill-kilo.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -629,7 +629,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/tools/skillgen/expected/graphify__skill-kiro.md b/tools/skillgen/expected/graphify__skill-kiro.md
index 8ec9ad2..b354243 100644
--- a/tools/skillgen/expected/graphify__skill-kiro.md
+++ b/tools/skillgen/expected/graphify__skill-kiro.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -629,7 +629,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/tools/skillgen/expected/graphify__skill-opencode.md b/tools/skillgen/expected/graphify__skill-opencode.md
index b023ff8..684e0e2 100644
--- a/tools/skillgen/expected/graphify__skill-opencode.md
+++ b/tools/skillgen/expected/graphify__skill-opencode.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -621,7 +621,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/tools/skillgen/expected/graphify__skill-pi.md b/tools/skillgen/expected/graphify__skill-pi.md
index 8ec9ad2..b354243 100644
--- a/tools/skillgen/expected/graphify__skill-pi.md
+++ b/tools/skillgen/expected/graphify__skill-pi.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -629,7 +629,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/tools/skillgen/expected/graphify__skill-trae.md b/tools/skillgen/expected/graphify__skill-trae.md
index a643daa..ac16b92 100644
--- a/tools/skillgen/expected/graphify__skill-trae.md
+++ b/tools/skillgen/expected/graphify__skill-trae.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -627,7 +627,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/tools/skillgen/expected/graphify__skill-vscode.md b/tools/skillgen/expected/graphify__skill-vscode.md
index f0719bf..31a3352 100644
--- a/tools/skillgen/expected/graphify__skill-vscode.md
+++ b/tools/skillgen/expected/graphify__skill-vscode.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -625,7 +625,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/tools/skillgen/expected/graphify__skill-windows.md b/tools/skillgen/expected/graphify__skill-windows.md
index f6c83fb..6ab0e02 100644
--- a/tools/skillgen/expected/graphify__skill-windows.md
+++ b/tools/skillgen/expected/graphify__skill-windows.md
@@ -651,7 +651,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/tools/skillgen/expected/graphify__skill.md b/tools/skillgen/expected/graphify__skill.md
index 8ec9ad2..b354243 100644
--- a/tools/skillgen/expected/graphify__skill.md
+++ b/tools/skillgen/expected/graphify__skill.md
@@ -77,7 +77,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -629,7 +629,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/tools/skillgen/fragments/core/aider.md b/tools/skillgen/fragments/core/aider.md
index c79b7b8..2ccf532 100644
--- a/tools/skillgen/fragments/core/aider.md
+++ b/tools/skillgen/fragments/core/aider.md
@@ -71,7 +71,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
diff --git a/tools/skillgen/fragments/core/core.md b/tools/skillgen/fragments/core/core.md
index a118947..0516b3a 100644
--- a/tools/skillgen/fragments/core/core.md
+++ b/tools/skillgen/fragments/core/core.md
@@ -564,7 +564,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/tools/skillgen/fragments/core/devin.md b/tools/skillgen/fragments/core/devin.md
index 6bbbeaf..13fb37c 100644
--- a/tools/skillgen/fragments/core/devin.md
+++ b/tools/skillgen/fragments/core/devin.md
@@ -82,7 +82,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
@@ -865,7 +865,7 @@ if [ ! -f graphify-out/.graphify_python ]; then
     GRAPHIFY_BIN=$(which graphify 2>/dev/null)
     if [ -n "$GRAPHIFY_BIN" ]; then
         PYTHON=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
-        case "$PYTHON" in *[!a-zA-Z0-9/_.-]*) PYTHON="python3" ;; esac
+        case "$PYTHON" in *[!a-zA-Z0-9/_.@-]*) PYTHON="python3" ;; esac
     else
         PYTHON="python3"
     fi
diff --git a/tools/skillgen/fragments/shell/posix.md b/tools/skillgen/fragments/shell/posix.md
index be3b8ab..717bd80 100644
--- a/tools/skillgen/fragments/shell/posix.md
+++ b/tools/skillgen/fragments/shell/posix.md
@@ -11,7 +11,7 @@ fi
 if [ -z "$PYTHON" ] && [ -n "$GRAPHIFY_BIN" ]; then
     _SHEBANG=$(head -1 "$GRAPHIFY_BIN" | tr -d '#!')
     case "$_SHEBANG" in
-        *[!a-zA-Z0-9/_.-]*) ;;
+        *[!a-zA-Z0-9/_.@-]*) ;;
         *) "$_SHEBANG" -c "import graphify" 2>/dev/null && PYTHON="$_SHEBANG" ;;
     esac
 fi
diff --git a/tools/skillgen/gen.py b/tools/skillgen/gen.py
index 7b198d1..0082e9e 100644
--- a/tools/skillgen/gen.py
+++ b/tools/skillgen/gen.py
@@ -864,6 +864,19 @@ def _is_no_api_key_fix_line(line: str) -> bool:
     return "graphify needs no API key" in line
 
 
+def _is_shebang_allowlist_fix_line(line: str) -> bool:
+    """Whether a line is part of the Homebrew ``python@`` shebang allowlist fix (#1586).
+
+    The interpreter-detection guard rejected any shebang containing a character
+    outside ``[!a-zA-Z0-9/_.-]``, but Homebrew installs versioned Python under
+    ``python@3.13``, so a valid interpreter path legitimately contains ``@`` and
+    detection fell through to a bare ``python3`` that lacked graphify. ``@`` is now
+    allowed, matching the #473 hooks.py fix; injection chars are still rejected.
+    Both the old (removed) and new (added) allowlist forms match here.
+    """
+    return "[!a-zA-Z0-9/_." in line
+
+
 # Every line that may differ between a rendered monolith and its pristine v8
 # baseline. Each predicate documents one sanctioned change-class; a blank line is
 # allowed because the multi-line fix blocks insert spacing. Anything else failing
@@ -878,6 +891,7 @@ _SANCTIONED_MONOLITH_DIFFS = (
     _is_zero_node_guard_fix_line,
     _is_manifest_root_fix_line,
     _is_no_api_key_fix_line,
+    _is_shebang_allowlist_fix_line,
 )