ipc, worker: dial and bind through netaddr (V-484)

Five hardcoded transports, three in internal/ipc and two in
internal/worker, all now go through the seam address. The unix perms
logic moved into netaddr, so the two copies of parentDir and the umask
dance are gone.

peerCaller already returned ok=false for a non-unix conn, so the
SO_PEERCRED path degrades correctly on tcp with no change.

internal/worker/client.go

@@ -24,6 +24,8 @@ import (
 	"net"
 	"sync"
 	"time"
+
+	"github.com/kami/maven/internal/netaddr"
 )
 
 // Client — one connection to one worker module. NOT goroutine-safe for
@@ -38,15 +40,25 @@ type Client struct {
 	dial func() (net.Conn, error)
 }
 
-// Dial opens a Client to the worker socket at path. The first call lazily
+// Dial opens a Client to the worker module at path. The first call lazily
 // dials; subsequent calls reuse the conn (a fresh dial happens on next call
 // after a teardown). Lazy dial keeps a worker that's restarting from
 // blocking core's startup; core attempts the dial on first use.
+//
+// path is a netaddr seam address. A bare path is the unix socket it has
+// always been; "tcp://workstation:9310?token=..." reaches a module on another
+// host, which is how stt and tts move to the machine with the GPU and the
+// microphone. A bad address surfaces on the first call, not here, because
+// Dial does not fail — see internal/netaddr.
 func Dial(path string) *Client {
+	addr, err := netaddr.Parse(path)
 	return &Client{
 		path: path,
 		dial: func() (net.Conn, error) {
-			return net.Dial("unix", path)
+			if err != nil {
+				return nil, err
+			}
+			return netaddr.Dial(addr)
 		},
 	}
 }

internal/worker/server.go

@@ -7,10 +7,11 @@
 // which module to dial; mixing the two is a config error caught cleanly by
 // the wire, not a runtime goroutine panic). One Server per module process.
 //
-// Socket perms mirror ipc.Server: dir 0700, socket 0600 ⇒ same unix user.
-// The module has no key, so the floor is "same user"; the wg/mTLS layers
-// are out of scope here (this socket never crosses the network radius —
-// it's local-only, point-to-point between two processes on the box).
+// The seam address decides the transport. On the default unix socket the
+// perms mirror ipc.Server — dir 0700, socket 0600 ⇒ same unix user — and that
+// is the whole auth floor, because the seam never leaves the box. A tcp
+// address moves the module to another host and takes that floor away, so
+// netaddr checks a shared token before the first frame. See internal/netaddr.
 package worker
 
 import (
@@ -18,11 +19,10 @@ import (
 	"encoding/json"
 	"fmt"
 	"net"
-	"os"
 	"sync"
 	"sync/atomic"
 
-	"golang.org/x/sys/unix"
+	"github.com/kami/maven/internal/netaddr"
 )
 
 // Server — a worker module process's listener. Wires either a Transcriber,
@@ -34,6 +34,7 @@ type Server struct {
 	s Synthesizer
 
 	path string
+	addr netaddr.Addr
 	ln   net.Listener
 
 	wg   sync.WaitGroup
@@ -61,25 +62,24 @@ func NewSynthesizerServer(path string, s Synthesizer) *Server {
 // two separate processes per the restart-free / fail-independent invariant).
 func (srv *Server) SetSynthesizer(s Synthesizer) { srv.s = s }
 
-// Listen binds the unix socket with 0700 dir + 0600 socket perms (same floor
-// as internal/ipc). A stale socket at path is removed first so the worker
-// process restarts cleanly after a crash, no manual cleanup needed.
+// Listen binds the seam address the Server was built with.
+//
+// A bare path is a unix socket with 0700 dir + 0600 socket perms, the same
+// floor as internal/ipc, and a stale socket is removed first so the worker
+// process restarts cleanly after a crash. A "tcp://host:port?token=..."
+// address binds a network listener instead, so this module can run on the
+// workstation while core stays on homesrv; the token is mandatory there,
+// because there is no filesystem to be the auth floor. See internal/netaddr.
 func (srv *Server) Listen() error {
-	_ = os.Remove(srv.path)
-	if err := os.MkdirAll(parentDir(srv.path), 0o700); err != nil {
-		return fmt.Errorf("worker: mkdir socket dir: %w", err)
-	}
-	oldMask := unix.Umask(0o077)
-	ln, err := net.Listen("unix", srv.path)
-	unix.Umask(oldMask)
+	addr, err := netaddr.Parse(srv.path)
 	if err != nil {
-		return fmt.Errorf("worker: listen %s: %w", srv.path, err)
+		return err
 	}
-	if err := os.Chmod(srv.path, 0o600); err != nil {
-		_ = ln.Close()
-		_ = os.Remove(srv.path)
-		return fmt.Errorf("worker: chmod socket: %w", err)
+	ln, err := netaddr.Listen(addr)
+	if err != nil {
+		return err
 	}
+	srv.addr = addr
 	srv.ln = ln
 	return nil
 }
@@ -193,7 +193,7 @@ func (srv *Server) Close() error {
 	}
 	err := srv.ln.Close()
 	srv.wg.Wait()
-	_ = os.Remove(srv.path)
+	netaddr.Cleanup(srv.addr)
 	return err
 }
 
@@ -214,15 +214,3 @@ func marshalResult(v any) json.RawMessage {
 	b, _ := json.Marshal(v)
 	return b
 }
-
-func parentDir(p string) string {
-	for i := len(p) - 1; i >= 0; i-- {
-		if p[i] == '/' {
-			if i == 0 {
-				return "/"
-			}
-			return p[:i]
-		}
-	}
-	return "."
-}