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claude-code: load MCP config via plugin dir

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Claude Code rejects `--mcp-config` once the Home Manager wrapper injects
it around subcommands, which breaks commands like `claude mcp list`.
Claude Code 2.1.76 fixed `--plugin-dir` so it no longer consumes
following subcommands, so use that path for the generated MCP config
instead.

Generate a plugin directory with a manifest and `.mcp.json`, wrap
`claude` with `--plugin-dir` before user arguments, and snapshot that
wrapper directly in the tests. Keep the existing LSP support in the
generated plugin directory as well, and add coverage for the combined
MCP+LSP case plus the MCP integration merge path.

Signed-off-by: Austin Horstman <khaneliman12@gmail.com>
This commit is contained in:
Austin Horstman 2026-03-18 16:57:42 -05:00
parent d47357a4c8
commit 4fcef56c15
11 changed files with 205 additions and 39 deletions
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56
modules/programs/claude-code.nix
View file

@ -469,39 +469,39 @@ in
programs.claude-code.finalPackage =
let
mergedMcpServers = transformedMcpServers // cfg.mcpServers;
makeWrapperArgs = lib.flatten (
lib.filter (x: x != [ ]) [
(lib.optional (cfg.mcpServers != { } || transformedMcpServers != { }) [
"--append-flags"
"--mcp-config ${
jsonFormat.generate "claude-code-mcp-config.json" { mcpServers = mergedMcpServers; }
}"
])
(lib.optional (cfg.lspServers != { }) [
"--append-flags"
"--plugin-dir ${
pkgs.runCommand "claude-code-lsp-plugin" { } ''
install -Dm644 ${
jsonFormat.generate "claude-code-lsp-plugin.json" {
name = "claude-code-lsp";
lspServers = cfg.lspServers;
}
} $out/.claude-plugin/plugin.json
''
}"
])
]
);
hasWrapperArgs = makeWrapperArgs != [ ];
hasMcpServers = mergedMcpServers != { };
hasLspServers = cfg.lspServers != { };
pluginDir =
if hasMcpServers || hasLspServers then
pkgs.runCommand "claude-code-hm-plugin" { } ''
install -Dm644 ${
jsonFormat.generate "claude-code-plugin.json" {
name = "claude-code-home-manager";
}
} $out/.claude-plugin/plugin.json
${lib.optionalString hasMcpServers ''
install -Dm644 ${
jsonFormat.generate "claude-code-mcp.json" { mcpServers = mergedMcpServers; }
} $out/.mcp.json
''}
${lib.optionalString hasLspServers ''
install -Dm644 ${jsonFormat.generate "claude-code-lsp.json" cfg.lspServers} $out/.lsp.json
''}
''
else
null;
in
if hasWrapperArgs then
if pluginDir != null then
pkgs.symlinkJoin {
name = "claude-code";
paths = [ cfg.package ];
nativeBuildInputs = [ pkgs.makeWrapper ];
postBuild = ''
wrapProgram $out/bin/claude ${lib.escapeShellArgs makeWrapperArgs}
mv $out/bin/claude $out/bin/.claude-wrapped
cat > $out/bin/claude <<EOF
#! ${pkgs.bash}/bin/bash -e
exec -a "\$0" "$out/bin/.claude-wrapped" --plugin-dir ${pluginDir} "\$@"
EOF
chmod +x $out/bin/claude
'';
inherit (cfg.package) meta;
}