feat: /realm in TUI, daemon instance takeover (0.9.16)

Pidfile records instance+port; login restarts the service when the seat
changes. TUI /realm status|login|stop; prompts discourage filler chatter.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/parliament_daemon.c

@@ -41,21 +41,53 @@ int cst_parliament_daemon_pidfile(char *out, size_t n) {
   return os_path_join(out, n, dir, "parliament.pid");
 }
 
-static int read_pid(void) {
+typedef struct {
+  int pid;
+  char instance[64];
+  int port;
+} daemon_meta_t;
+
+static int read_meta(daemon_meta_t *m) {
+  memset(m, 0, sizeof(*m));
+  m->pid = -1;
   char path[OS_PATH_MAX];
   if (cst_parliament_daemon_pidfile(path, sizeof(path)) != 0)
     return -1;
   FILE *f = fopen(path, "rb");
   if (!f)
     return -1;
-  int pid = -1;
-  if (fscanf(f, "%d", &pid) != 1)
-    pid = -1;
+  char line[256];
+  while (fgets(line, sizeof(line), f)) {
+    if (!strncmp(line, "pid=", 4))
+      m->pid = atoi(line + 4);
+    else if (!strncmp(line, "instance=", 9)) {
+      const char *p = line + 9;
+      size_t i = 0;
+      while (p[i] && p[i] != '\n' && p[i] != '\r' &&
+             i + 1 < sizeof(m->instance)) {
+        m->instance[i] = p[i];
+        i++;
+      }
+      m->instance[i] = 0;
+    } else if (!strncmp(line, "port=", 5))
+      m->port = atoi(line + 5);
+    else if (m->pid <= 0) {
+      /* Legacy single-line pidfile. */
+      int pid = atoi(line);
+      if (pid > 0)
+        m->pid = pid;
+    }
+  }
   fclose(f);
-  return pid;
+  return m->pid > 0 ? 0 : -1;
 }
 
-static int write_pid(int pid) {
+static int read_pid(void) {
+  daemon_meta_t m;
+  return read_meta(&m) == 0 ? m.pid : -1;
+}
+
+static int write_pid(int pid, const char *instance_id, int peer_port) {
   char path[OS_PATH_MAX], tmp[OS_PATH_MAX + 8];
   if (cst_parliament_daemon_pidfile(path, sizeof(path)) != 0)
     return -1;
@@ -64,7 +96,9 @@ static int write_pid(int pid) {
   FILE *f = fopen(tmp, "wb");
   if (!f)
     return -1;
-  int ok = fprintf(f, "%d\n", pid) > 0;
+  int ok = fprintf(f, "pid=%d\ninstance=%s\nport=%d\n", pid,
+                   instance_id ? instance_id : "",
+                   peer_port > 0 ? peer_port : 0) > 0;
   if (fclose(f) != 0)
     ok = 0;
   if (!ok) {
@@ -80,8 +114,7 @@ static void clear_pid(void) {
     remove(path);
 }
 
-int cst_parliament_daemon_running(void) {
-  int pid = read_pid();
+static int pid_alive(int pid) {
   if (pid <= 0)
     return 0;
 #ifdef _WIN32
@@ -95,6 +128,34 @@ int cst_parliament_daemon_running(void) {
 #endif
 }
 
+int cst_parliament_daemon_running(void) {
+  daemon_meta_t m;
+  if (read_meta(&m) != 0)
+    return 0;
+  if (!pid_alive(m.pid)) {
+    clear_pid();
+    return 0;
+  }
+  return 1;
+}
+
+int cst_parliament_daemon_info(int *pid_out, char *instance_out, size_t in_sz,
+                               int *port_out) {
+  daemon_meta_t m;
+  if (read_meta(&m) != 0 || !pid_alive(m.pid)) {
+    if (read_meta(&m) == 0 && !pid_alive(m.pid))
+      clear_pid();
+    return -1;
+  }
+  if (pid_out)
+    *pid_out = m.pid;
+  if (instance_out && in_sz)
+    snprintf(instance_out, in_sz, "%s", m.instance);
+  if (port_out)
+    *port_out = m.port;
+  return 0;
+}
+
 static void sleep_ms(int ms) {
 #ifdef _WIN32
   Sleep((DWORD)ms);
@@ -194,7 +255,8 @@ int cst_parliament_daemon_run(const char *password, const char *instance_id,
 #else
       (int)getpid()
 #endif
-  );
+      ,
+      instance_id, bound);
   fprintf(stderr, "parliament_service pid=%d port=%d id=%s realm=%s\n",
 #ifdef _WIN32
           (int)GetCurrentProcessId(),
@@ -273,8 +335,25 @@ int cst_parliament_daemon_start(const char *password, const char *instance_id,
                                 int peer_port, char *err, size_t err_sz) {
   if (err && err_sz)
     err[0] = 0;
-  if (cst_parliament_daemon_running())
-    return 0;
+  if (!instance_id || !instance_id[0]) {
+    if (err && err_sz)
+      snprintf(err, err_sz, "instance id required");
+    return -1;
+  }
+  int want_port = peer_port > 0 ? peer_port : 9100;
+  {
+    int cur_pid = 0, cur_port = 0;
+    char cur_id[64] = {0};
+    if (cst_parliament_daemon_info(&cur_pid, cur_id, sizeof(cur_id),
+                                   &cur_port) == 0) {
+      int same = (!cur_id[0] || strcmp(cur_id, instance_id) == 0) &&
+                 (cur_port <= 0 || cur_port == want_port);
+      if (same)
+        return 0;
+      /* Different seat or port: take over. */
+      (void)cst_parliament_daemon_stop();
+    }
+  }
 #ifdef _WIN32
   /* Windows: run in-process foreground loop under a detached console is
    * deferred; callers should use --service in a service manager. */
@@ -294,9 +373,13 @@ int cst_parliament_daemon_start(const char *password, const char *instance_id,
     return -1;
   }
   if (pid > 0) {
-    /* Parent: wait briefly for pidfile. */
+    /* Parent: wait briefly for matching pidfile. */
     for (int i = 0; i < 50; i++) {
-      if (cst_parliament_daemon_running())
+      int cur_pid = 0, cur_port = 0;
+      char cur_id[64] = {0};
+      if (cst_parliament_daemon_info(&cur_pid, cur_id, sizeof(cur_id),
+                                     &cur_port) == 0 &&
+          (!cur_id[0] || strcmp(cur_id, instance_id) == 0))
         return 0;
       sleep_ms(50);
     }
@@ -314,7 +397,7 @@ int cst_parliament_daemon_start(const char *password, const char *instance_id,
       close(fd);
   }
   char derr[256];
-  (void)cst_parliament_daemon_run(password, instance_id, peer_port, derr,
+  (void)cst_parliament_daemon_run(password, instance_id, want_port, derr,
                                   sizeof(derr));
   _exit(0);
 #endif