feat: parliament daemon, login gate, peer context sync (0.9.13)

Login claims the chair, writes a session ticket, and starts a background
service for discovery plus revision-based context sync. Password Realm
opens require --login (or CST_REALM_PASSWORD); --service/--service-stop
manage the resident agent.

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

src/parliament.c

@@ -165,7 +165,7 @@ int cst_parliament_claim_chair(const char *instance_id,
   return cst_parliament_save(&m);
 }
 
-int cst_parliament_context_put(const char *text) {
+static int context_write_file(const char *text) {
   char path[OS_PATH_MAX], tmp[OS_PATH_MAX + 8];
   if (context_path(path, sizeof(path)) != 0)
     return -1;
@@ -185,6 +185,12 @@ int cst_parliament_context_put(const char *text) {
     remove(tmp);
     return -1;
   }
+  return 0;
+}
+
+int cst_parliament_context_put(const char *text) {
+  if (context_write_file(text) != 0)
+    return -1;
   cst_parliament_meta_t m;
   if (cst_parliament_load(&m) == 0) {
     m.revision++;
@@ -290,8 +296,115 @@ char *cst_parliament_login(const char *password, const char *instance_id,
   cst_buf_puts(&hand, ctx ? ctx : "");
   free(ctx);
   free(dev);
+  if (cst_parliament_session_write(instance_id) != 0) {
+    if (err && err_sz)
+      snprintf(err, err_sz, "session ticket write failed");
+    crypto_wipe(keys.seed, sizeof(keys.seed));
+    crypto_wipe(keys.sk, sizeof(keys.sk));
+    crypto_wipe(sk, sizeof(sk));
+    cst_buf_free(&hand);
+    return NULL;
+  }
   crypto_wipe(keys.seed, sizeof(keys.seed));
   crypto_wipe(keys.sk, sizeof(keys.sk));
   crypto_wipe(sk, sizeof(sk));
   return cst_buf_steal(&hand);
 }
+
+static int session_path(char *out, size_t n) {
+  char dir[OS_PATH_MAX];
+  if (cst_realm_dir(dir, sizeof(dir)) != 0)
+    return -1;
+  return os_path_join(out, n, dir, "chair.session");
+}
+
+int cst_parliament_session_write(const char *instance_id) {
+  if (!instance_id || !instance_id[0])
+    return -1;
+  char path[OS_PATH_MAX], tmp[OS_PATH_MAX + 8];
+  if (session_path(path, sizeof(path)) != 0)
+    return -1;
+  if (snprintf(tmp, sizeof(tmp), "%s.tmp", path) >= (int)sizeof(tmp))
+    return -1;
+  FILE *f = fopen(tmp, "wb");
+  if (!f)
+    return -1;
+  int ok = fprintf(f, "instance=%s\nissued=%ld\n", instance_id,
+                   (long)time(NULL)) > 0;
+  if (fclose(f) != 0)
+    ok = 0;
+  if (!ok) {
+    remove(tmp);
+    return -1;
+  }
+  if (os_rename_replace(tmp, path) != 0) {
+    remove(tmp);
+    return -1;
+  }
+  return 0;
+}
+
+int cst_parliament_session_ok(char *instance_id_out, size_t n) {
+  char path[OS_PATH_MAX];
+  if (session_path(path, sizeof(path)) != 0)
+    return 0;
+  FILE *f = fopen(path, "rb");
+  if (!f)
+    return 0;
+  char line[256], iid[64] = {0};
+  long issued = 0;
+  while (fgets(line, sizeof(line), f)) {
+    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(iid)) {
+        iid[i] = p[i];
+        i++;
+      }
+      iid[i] = 0;
+    } else if (!strncmp(line, "issued=", 7))
+      issued = atol(line + 7);
+  }
+  fclose(f);
+  if (!iid[0] || issued <= 0)
+    return 0;
+  /* Ticket valid for 24h of wall clock. */
+  long now = (long)time(NULL);
+  if (now < issued || now - issued > 86400)
+    return 0;
+  cst_parliament_meta_t m;
+  if (cst_parliament_load(&m) != 0)
+    return 0;
+  if (!m.chair_instance[0] || strcmp(m.chair_instance, iid) != 0)
+    return 0;
+  if (instance_id_out && n)
+    snprintf(instance_id_out, n, "%s", iid);
+  return 1;
+}
+
+void cst_parliament_session_clear(void) {
+  char path[OS_PATH_MAX];
+  if (session_path(path, sizeof(path)) == 0)
+    remove(path);
+}
+
+int cst_parliament_apply_sync(unsigned long revision, const char *parliament_id,
+                              const char *project_id, const char *chair,
+                              const char *context) {
+  cst_parliament_meta_t m;
+  if (cst_parliament_load(&m) != 0)
+    return -1;
+  if (revision <= m.revision)
+    return 0;
+  if (parliament_id && parliament_id[0])
+    snprintf(m.parliament_id, sizeof(m.parliament_id), "%s", parliament_id);
+  if (project_id)
+    snprintf(m.project_id, sizeof(m.project_id), "%s", project_id);
+  if (chair)
+    snprintf(m.chair_instance, sizeof(m.chair_instance), "%s", chair);
+  m.revision = revision;
+  snprintf(m.status, sizeof(m.status), "%s", "open");
+  if (context_write_file(context ? context : "") != 0)
+    return -1;
+  return cst_parliament_save(&m);
+}