Auto-wire Primo MCP during `primo init`

[elemdos]

Goal

After primo init, the user's installed MCP clients have a primo server entry pointing at primo-mcp, with zero manual JSON editing.

Today users have to find their MCP client's config file, paste a JSON snippet, and restart the client — every client, every machine. For an "AI-native visual CMS" pitch this is the first onboarding friction users hit.

Scope

In:

• Detect installed clients by checking known config paths (Claude Desktop, Claude Code, Cursor on macOS/Linux/Windows).
• Prompt with a checklist of detected clients ("Wire up Primo MCP for: ☑ Claude Code ☑ Cursor ☐ Claude Desktop").
• Merge a new primo server entry into each selected client's config without clobbering existing entries.
• primo-mcp as a runtime dependency of primo-cli so it's already on disk (skip npx's first-run resolution wait).
• Idempotent — re-running in a workspace already wired is a no-op ("already wired ✓").
• Flag to skip: primo init --no-mcp.

Out (defer):

• Auto-wiring on primo new if init already ran.
• Per-site mcpServers config files (Cursor's per-repo .cursor/mcp.json — addable later).
• Non-mainstream clients (Continue, Zed, Windsurf).
• Reverting on primo uninstall — npm doesn't run uninstall hooks reliably.

Architecture

New module: primo-cli/src/utils/mcp-wiring.ts

detect_clients() → Array<ClientInfo>
wire_client(client, server_entry) → { written, already_present }
run_mcp_wiring(opts) → void

Per-client config paths:

Client	macOS	Linux	Windows
Claude Desktop	~/Library/Application Support/Claude/claude_desktop_config.json	~/.config/Claude/claude_desktop_config.json	%APPDATA%/Claude/claude_desktop_config.json
Claude Code	~/.claude/settings.json (or claude mcp add shell-out)	same	%USERPROFILE%/.claude/settings.json
Cursor	~/.cursor/mcp.json	~/.cursor/mcp.json	%USERPROFILE%/.cursor/mcp.json

Server entry shape (same across all three):

{ "mcpServers": { "primo": { "command": "npx", "args": ["-y", "primo-mcp"] } } }

Wiring integration points

• init.ts — after workspace files are written, call run_mcp_wiring({ skip: opts.noMcp }). Print a one-line summary.
• new.ts — no change. Init handles it.
• package.json — "primo-mcp": "^0.1.0" to deps. Optional follow-up: detect local install and skip npx -y.

Edge cases

1. Config file exists but isn't JSON — skip with warning, don't crash.
2. Config has mcpServers.primo already — leave alone, print "already wired ✓".
3. Config has mcpServers.primo pointing elsewhere (e.g. user's local dist path) — prompt: "Existing primo entry points at X. Replace with npx primo-mcp?" (default: yes).
4. No write permission — surface the error path.
5. Claude Code shell-out — if claude CLI is on $PATH, prefer claude mcp add primo -- npx -y primo-mcp over JSON-rewriting ~/.claude/settings.json. Fall back to JSON if not on PATH.

Phasing

• Phase 1: bundle primo-mcp as dep + Claude Code only (via claude mcp add). Highest-value, easiest. ~1 PR, ~100 LOC.
• Phase 2: Cursor + Claude Desktop JSON merging.
• Phase 3: idempotency polish + --no-mcp flag + messaging.

Total realistic effort: ~1-2 days for Phase 1, another ~1-2 for Phase 2+3.

Open questions

1. Should this also run on primo dev if MCP isn't wired? Or strictly init-time?
2. Auto-update entry on primo-cli upgrade if schema changes? Probably not — too aggressive.
3. Should primo new re-check (quiet, idempotent) in case user added a new client since init?

Workaround today

Users have to hand-edit their MCP client config:

{ "mcpServers": { "primo": { "command": "npx", "args": ["-y", "primo-mcp"] } } }

Config paths above. Restart the client after editing.