Prove the controller's published state files

The lifecycle harness gains the state-files scenario: with GF_STATE_DIR
at the session workdir, grbl.settings carries the $$ view and follows
the derived floor through an M101 switch and its M2 revert, and
grbl.state follows the sender connection (a reconnect bumps the
generation), the armed window and the dose model, with ts_mono
advancing. The panel-serves catalog test asserts the /status grbl block
in GRBL mode with a live controller (fresh age, state, sender, laser,
modals) and GET /grbl/settings, and its covers name the publisher and
the serial layer; the glowforge_status.c covers entry selects nothing
until the grblHAL pin moves past the commit that adds the file. The
CAMPAIGN-LOG records the build and its proof; BRINGUP describes the
mechanism.

scripts/bench/laser_lifecycle_test.py

@@ -28,7 +28,12 @@ reported messages:
      reset with the position kept (no alarm), the head returns to the
      job start on its own; with lid_policy = hold the stock door hold and
      cycle-start resume apply
-  9. the job start survives a pause: a job paused and resumed by the
+  9. the controller publishes its state for the daemon: grbl.settings
+     (the $$ view) and grbl.state (JSON with ts_mono, machine state,
+     sender session, laser window and dose model, modals) appear under
+     GF_STATE_DIR, follow the sender connection, the armed window and
+     an M101 switch, and carry a fresh ts_mono
+ 10. the job start survives a pause: a job paused and resumed by the
      button, then cancelled by the lid, returns to where the job began,
      not to where it was paused (the core restarts a held cycle through
      Idle); a job abandoned in a hold and reset ends there, so the next
@@ -158,7 +163,7 @@ class Session:
             f.write("laser_disarm_s = %d\n%s" % (disarm_s, conf_extra))
         verdict = os.path.join(self.workdir, "cooling.state")
         env = dict(os.environ, GF_VERDICT_FILE=verdict, GFHOME_CONF=conf,
-                   FFLOG_STDERR="1")
+                   GF_STATE_DIR=self.workdir, FFLOG_STDERR="1")
         env.pop("GFSINK", None)
         env.pop("GF_SWITCH_FILE", None)
         self.switch_file = None
@@ -260,6 +265,74 @@ class Session:
         shutil.rmtree(self.workdir, ignore_errors=True)
 
 
+def read_state(sess, key=None, timeout=8.0):
+    """The published grbl.state as text, polled until `key` appears (the
+    publisher runs on the protocol thread's pace; a '?' keeps it ticking)."""
+    path = os.path.join(sess.workdir, "grbl.state")
+    deadline = time.time() + timeout
+    text = ""
+    while time.time() < deadline:
+        sess.sock.sendall(b"?")
+        read_avail(sess.sock, sess.log, 0.2)
+        try:
+            with open(path) as f:
+                text = f.read()
+        except OSError:
+            text = ""
+        if text.endswith("\n") and (key is None or key in text):
+            return text
+        time.sleep(0.2)
+    return text
+
+
+def test_status_files():
+    print("state files: settings and state published, following the edges")
+    s = Session("state-files", disarm_s=30)
+    try:
+        st = read_state(s, '"connected":true')
+        assert '"state":"Idle"' in st, "state file lacks Idle: %r" % st
+        assert '"connected":true' in st, "sender not reported connected: %r" % st
+        assert '"armed":false' in st, "armed before any job: %r" % st
+        assert '"model":"density"' in st and '"floor_pct":10' in st, \
+            "model/floor missing: %r" % st
+        assert '"modals":"[GC:' in st, "modal report missing: %r" % st
+        ts0 = float(st.split('"ts_mono":')[1].split(',')[0])
+
+        cfg = open(os.path.join(s.workdir, "grbl.settings")).read()
+        assert "$35=" in cfg and "$30=" in cfg, "settings file lacks $ lines"
+
+        # The armed window and a dose-model switch reach the file.
+        send_line(s.sock, "G91", s.log)
+        send_line(s.sock, "M3 S100", s.log)
+        st = read_state(s, '"armed":true')
+        assert '"armed":true' in st, "armed window not published: %r" % st
+        send_line(s.sock, "M5", s.log)
+        send_line(s.sock, "M101 P0", s.log)
+        st = read_state(s, '"model":"analog"')
+        assert '"model":"analog"' in st and '"floor_pct":16' in st, \
+            "the M101 switch not published: %r" % st
+        cfg = open(os.path.join(s.workdir, "grbl.settings")).read()
+        assert "$35=16" in cfg, "the switched floor not republished: %r" % [
+            l for l in cfg.splitlines() if l.startswith("$35")]
+        send_line(s.sock, "M2", s.log)
+        st = read_state(s, '"model":"density"')
+        assert '"model":"density"' in st, "the M2 revert not published: %r" % st
+
+        # A reconnect bumps the generation and stays connected.
+        gen0 = int(st.split('"generation":')[1].split(',')[0])
+        s.sock.close()
+        s.sock = s.connect()
+        st = read_state(s, '"connected":true')
+        gen1 = int(st.split('"generation":')[1].split(',')[0])
+        assert gen1 > gen0, "generation did not advance on reconnect (%d -> %d)" % (gen0, gen1)
+        ts1 = float(st.split('"ts_mono":')[1].split(',')[0])
+        assert ts1 > ts0, "ts_mono did not advance"
+        print("PASS [state-files]: published, armed/switch/revert followed, "
+              "generation %d -> %d" % (gen0, gen1))
+    finally:
+        s.close()
+
+
 def test_job_window():
     """Rules 1 + 2: arm once per job, persist across M5/M3, close at M2,
     fresh consent for the next job. The grace is set far beyond the test
@@ -724,6 +797,7 @@ def main():
     if not os.path.isfile(BIN):
         fail("controller binary not found at %s" % BIN)
     test_job_window()
+    test_status_files()
     test_sender_change()
     test_sender_change_mid_job()
     test_rx_overrun_aborts()