forgetest: the camera-home tests hand the head back where they found it

homing.cloud-offsets, setup.check-envelope and cloud.mode-switch let the
service move the head, and ended with it where the service left it: at
the camera home, or, in cloud.mode-switch, under the camera, where the
service's re-hunt had taken it. Each told the baseline the counters had
been re-zeroed at the starting position, so the hand-back saw nothing to
do. No counter reading can say where the head was found: every service
motion zeroes the counters at its start, and the home and every
controller start zero them again.

suite/homeoff.py now holds the helpers for a test that lets the service
move the head:

- session_travel sums a client's own record of each motion's end ("end
  positions (x, y, z)", the counters the motion zeroed at its start, in
  x8 steps, the one mode a service motion runs at). A motion with no end
  on record, or a log rotated under the run, leaves the travel unknown.
- camera_home_return drops the camera home, jogs the head back by the
  session's travel plus what the counters read since the home, starts
  the controller once more so the counters read zero where the head
  began, and tells the baseline. cloud_mode_return does the same for a
  stay in cloud mode, from the cloud client's log.
- A travel that cannot be known fails the run and moves nothing. A
  hand-back that fails while the test is already failing is logged, and
  the test's own failure is the one reported.
- judge_whole_motions fails a homing motion that stopped short: the
  position declared after it is false.

cloud.mode-switch imports the helpers inside its function, so no other
cloud test's fingerprint moves. Its cloud stretch no longer goes through
return_head, which read 0/0 after the controller's start and left the
head under the camera.

Proof: tests/test_camera_home_return.py, 15 cases on the machine's own
log lines (a session stopped short, a whole three-motion one, a cut log,
a refused motion, homed and unhomed counters, a restart since the home,
the first failure winning). tests/test_cloud_suite.py's mode-switch fakes
now zero the counters and remove the anchor at a controller start, write
the anchor at the home, and move the counters on a jog: 10 cases, a
failed hand-back that must not hide the test's failure among them.
forgetest 498 OK. On the bench reference, with the driver and the runner
fixes: homing.cloud-offsets, setup.check-envelope and cloud.mode-switch
PASS, each ending with the head where it was found; cloud.mode-switch
jogged its cloud stretch 246.06/139.01 mm back with the counters across
the jog agreeing, and every baseline was clean.

Acceptance: the three tests are the change; their fingerprints move and
no other test's does.

forgetest/forgetest/suite/cloud.py

@@ -254,8 +254,8 @@ def gfhome_homing(ctx, ev, g):
              "Open the lid the moment you are told, with a hand ready on it: the cloud client's "
              "first hunt begins a few seconds after its controller starts and must find the lid "
              "open. Leave it open through the connect and the hunt; close it when told. Nothing "
-             "else: the switch back and the $H homing run on their own, and the head ends parked "
-             "at the home corner."],
+             "else: the switch back and the $H homing run on their own, and the head ends where the "
+             "test found it."],
       description="One round trip with the two service-driven motions on it. POST /mode switches "
                   "to the cloud controller with the lid closed (no controller starts with the "
                   "enclosure open): gfcloud comes up under supervision, authenticates and "
@@ -268,11 +268,18 @@ def gfhome_homing(ctx, ev, g):
                   "is measured by the airflow gates but not judged (no AIRFLOW, the exhaust row "
                   "reads unjudged); the camera service survives the switch. The lid closed, the "
                   "service's re-hunt is waited out; switching back brings grblHAL up with the Grbl "
-                  "port open and Idle, and the head returns to its start. Then $H with "
+                  "port open and Idle, and the head returns to its start by the travel the "
+                  "client logged for the service's motions. Then $H with "
                   "homing_mode = gfcloud runs gfhome, the web-service homing session with the "
                   "head-accelerometer motion witness: the controller returns to Idle with "
-                  "homed:true and gfhome reports the homing complete with the motion it saw.")
+                  "homed:true, gfhome reports the homing complete with the motion it saw, and "
+                  "every service motion of the session ran whole. The camera home is then "
+                  "dropped and the head goes back to where the test found it, by the travel the "
+                  "session's motions logged.")
 def mode_switch(ctx):
+    # The hand-back helpers, imported here so that no other cloud test's
+    # fingerprint moves.
+    from .homeoff import camera_home_return, cloud_mode_return, judge_whole_motions, session_mark
     fc = ctx.forgectrl
     ev = ctx.evidence
     st, m0 = fc.get("/mode")
@@ -383,10 +390,9 @@ def mode_switch(ctx):
     st, cam2 = fc.get("/cam/status")
     ev["cam_after"] = cam2
     ctx.check(st == 200, "camera status lost after the switch back")
-    # cloud mode's connect cleared the kernel counters at the starting position
-    # and its hunt homed the head: bring it back
-    ctx.counters_rezeroed()
-    return_head(ctx)
+    # The service moved the head in cloud mode, and the controller's start
+    # zeroed the counters where it left it: the client's record brings it back.
+    cloud_mode_return(ctx, ev, log_offset)
     # cloud mode sets its own lid-lamp level (LLvl) and leaves it: hand back the level found
     lamp1 = hw.sysfs_read("pic/lid_led")
     ev["lid_lamp"] = {"before": lamp0, "after_cloud": lamp1}
@@ -400,9 +406,11 @@ def mode_switch(ctx):
         st, body = fc.post("/settings", data={"homing_mode": "gfcloud"})
         ctx.log("homing_mode=gfcloud for the homing -> %s %s", st, body if isinstance(body, str) else "")
         ctx.check(st == 200, "homing_mode=gfcloud -> %s %s", st, body)
+    session_at = session_mark()
     try:
         with ctx.grbl() as g:
             gfhome_homing(ctx, ev, g)
+            judge_whole_motions(ctx, ev, session_at)
     finally:
         if ev["homing_mode"] != "gfcloud":
             # Back to exactly what the machine had: unset is the empty
@@ -413,6 +421,7 @@ def mode_switch(ctx):
                         if not ev["homing_mode"]
                         else fc.post("/settings", data={"homing_mode": ev["homing_mode"]}))
             ctx.log("restore homing_mode=%r -> %s", ev["homing_mode"], st)
+        camera_home_return(ctx, ev, session_at)
     ctx.log("PASS: grbl -> cloud (session, hunt with the lid open, lens homed, airflow unjudged) -> "
             "grbl (port open, %s), then $H homed in %.1f s", ev["grbl_state"], ev["homing_s"])