link/claude: secrets in MCP specs, and a separate spec for Desktop

Two things a spec in ~/.config/claude/mcp-servers.d/ may now carry beyond
what Claude Code takes, both resolved at link time:

- "${szecret:NAME}" in any string value, replaced with `szecret get NAME`
  when the server is registered with Claude Code. For a remote server's
  Authorization header: Claude Code's own headersHelper is not run in a
  workspace without persisted trust, which includes $HOME, so a token
  fetched that way is simply missing. A secret that cannot be read skips
  that server, loudly.

- "desktop", a whole spec given to Claude Desktop instead. Desktop only
  starts local stdio servers, so a layer that moves a server to HTTP for
  Claude Code can keep Desktop on a local copy.

1 files changed, 42 insertions, 1 deletions

diff --git a/link/claude.sh b/link/claude.sh
index b7b3f9e..56f3724 100755
--- a/link/claude.sh
+++ b/link/claude.sh
@@ -31,6 +31,21 @@ link "$config_dir/claude/CLAUDE.md" "$HOME/.claude/CLAUDE.md"
 #
 # Run by link.sh after other layers' link.sh, so their files are in place on a
 # first link.
+#
+# Two things a spec may carry beyond what Claude Code takes, both resolved here:
+#
+#   "${szecret:NAME}"  anywhere in a string value, replaced with `szecret get
+#                      NAME` as the server is registered with Claude Code. For a
+#                      remote server's Authorization header: Claude Code's own
+#                      headersHelper is not run in a workspace without persisted
+#                      trust, which includes $HOME, so a token fetched there
+#                      would simply be missing. The secret ends up in
+#                      ~/.claude.json, which Claude Code keeps mode 600. A
+#                      secret that cannot be read skips that server, loudly.
+#
+#   "desktop"          a whole spec to give Claude Desktop instead of this one,
+#                      e.g. a local stdio server where Claude Code gets a remote
+#                      one. Claude Code never sees it.
 mcp_dir="$xdg_config_dir/claude/mcp-servers.d"
 mcp_manifest="${XDG_STATE_HOME:-$HOME/.local/state}/dotfiles/claude-mcp-servers"
 claude_desktop_dir="$HOME/Library/Application Support/Claude"
@@ -105,9 +120,34 @@ then
     then
       echo "Will register MCP server (user scope): $name"
     else
+      if ! code_spec="$(python3 -c 'import json, re, subprocess, sys
+spec = json.loads(sys.argv[1])
+spec.pop("desktop", None)
+
+def secret(match):
+    name = match.group(1)
+    try:
+        return subprocess.run(["szecret", "get", name], check=True, capture_output=True, text=True).stdout.strip()
+    except (OSError, subprocess.CalledProcessError):
+        sys.exit("szecret get %s failed" % name)
+
+def expand(value):
+    if isinstance(value, str):
+        return re.sub(r"\$\{szecret:([A-Za-z0-9._-]+)\}", secret, value)
+    if isinstance(value, dict):
+        return {k: expand(v) for k, v in value.items()}
+    if isinstance(value, list):
+        return [expand(v) for v in value]
+    return value
+
+print(json.dumps(expand(spec)))' "$spec" 2>&1)"
+      then
+        red "MCP server (user scope) not registered: $name: $code_spec"
+        continue
+      fi
       green "MCP server (user scope): $name"
       claude mcp remove --scope user "$name" >/dev/null 2>&1 || true
-      claude mcp add-json --scope user "$name" "$spec" >/dev/null
+      claude mcp add-json --scope user "$name" "$code_spec" >/dev/null
     fi
   done <<< "$mcp_wanted"
 fi
@@ -149,6 +189,7 @@ for line in os.environ["MCP_WANTED"].splitlines():
         continue
     name, spec = line.split("\t", 1)
     spec = json.loads(spec)
+    spec = spec.get("desktop", spec)
     command = spec.get("command")
     if command:
         if not os.path.isabs(command):