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Introduces `previewsmcp serve --daemon`, which runs the MCP server on a
Unix domain socket at ~/.previewsmcp/serve.sock. Multiple CLI clients can
connect concurrently; each connection gets its own MCP.Server instance
sharing module-level state (IOSState, ConfigCache) for consistent session
visibility.
New commands:
- `serve --daemon` — starts the daemon listener
- `status` — reports daemon liveness via socket connect
- `kill-daemon` — graceful SIGTERM with stale PID cleanup
Supporting infrastructure:
- DaemonPaths — filesystem constants (~/.previewsmcp/{serve.sock, serve.pid})
- DaemonLifecycle — PID file management + signal handlers
- DaemonListener — NWListener on UDS, accepts connections, spawns per-conn servers
Existing `serve` (stdio mode, used by Claude/Cursor MCP integration) is
unchanged and its integration tests still pass.
First PR in the stack for the CLI/MCP parity spec (docs/cli-mcp-parity-spec.md).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Changes from self-review of PR 97: - Critical: fix startup race where a second `serve --daemon` could unlink the first daemon's socket and clobber it. Previous check was PID-based, which misses the window between bind and PID-write (and also misses the case where someone deletes the PID file manually). Replaces with a socket `connect()` probe via new DaemonProbe module — authoritative since the kernel tracks socket-to-fd associations atomically. - Share Compiler across daemon connections. `configureMCPServer` now accepts `sharedCompiler:`; DaemonListener builds one at startup and passes it to each accepted connection, avoiding ~seconds of per-client xcrun/SDK resolution cost. Stdio mode still creates its own. - Extract `DaemonProbe.canConnect()` — shared by ServeCommand (startup guard) and StatusCommand (liveness report). Previously duplicated. - Extract `DaemonLifecycle.daemonRunningPID()` — returns PID only if alive, replaces two-step readPID/isProcessAlive calls at three sites. - Readability: - Remove unneeded @mainactor from DaemonListener.start - Replace clever AsyncStream-based ready-signaling with withCheckedThrowingContinuation - Remove dead runForever() (NSApp.run() handles this) - Add regression test secondDaemonRefusesWithMissingPIDFile that would hang without the fix (second daemon rebinds and runs forever). Uses a bounded wait so it fails fast if the race returns. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
obj-p
changed the title
This was referenced Apr 14, 2026
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Feature branch — do not merge until all child PRs land
This is the umbrella feature branch for the CLI/MCP parity work described in docs/cli-mcp-parity-spec.md.
Workflow:
cli-mcp-parity(notmain).mainas a single feature.Current contents (PR 1 of plan)
Daemon foundation — landed as the initial commit on this branch:
previewsmcp serve --daemon— runs MCP server on~/.previewsmcp/serve.sockpreviewsmcp status— reports daemon livenesspreviewsmcp kill-daemon— graceful SIGTERMNWEndpoint.unix)MCP.Serverper connection, sharing module-level state + a singleCompilerIncludes 7 daemon lifecycle integration tests. All MCP stdio paths (Claude/Cursor integration) unchanged and still passing.
Pending child PRs
Per the spec's stacked plan:
DaemonClient+runmigration (+--detach)snapshotmagical reuseconfigureswitchelements(iOS)touch(iOS)simulatorsstopvariantsmigrationRelated
runcommand has no way to capture a snapshot of the running preview #92, CLI/MCP parity: run command lacks interactive capabilities #94runsessions #95 (interactive REPL)🤖 Generated with Claude Code