lab: the iOS connect path verifies what it started, and both Android branches explain themselves

iOS: connect_phone launched the app with its own copy of the devicectl
line and returned success if the LAUNCH returned 0 - which says the app
started and nothing more, so a phone that never loaded an experiment was
reported as connected and failed later on "no data". It now goes through
device.py's launcher (which also carries the fallback for phones
devicectl cannot talk to) and then waits for the remote API, exactly as
Android does. The failure names where to look: the app's own
"-phyphoxBleConnect: no device advertising as X turned up within 60 s"
line in the device console, the Bluetooth permission, and whether the
installed build has the seam. Worth saying in the message because
-phyphoxBleConnect opens NO dialog by design - the app scans headlessly,
so "nothing visible happened" is not evidence of anything.

Android: the two failure branches had drifted. The hold branch reports
the first exception and keeps the whole output; the API branch still
tailed 300 characters, which is why the single failure of today's last
pass came back as "...within the connect timeout:
de.rwth_aachen.phyphox.BleCompatConnectTest:" and nothing else. Both go
through one explainer now.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: Staacks

tools/lab/ble.py

@@ -579,6 +579,33 @@ def _await_hold(dev, timeout):
 TRANSFER_FILE = "files/temp_bt/bt.phyphox"
 
 
+def _instrumentation_cause(dev, scenario, args, out):
+    """The first exception with the lines under it, plus the whole output
+    kept as evidence. Returns a string to append to a finding.
+
+    Shared by both failure branches on purpose. The hold branch learned
+    this on 2026-08-28 (eight failures reported as JUnit's header line
+    with the cause thrown away) and the API branch did not, so the one
+    remaining failure of that day's last pass came back as
+    "...within the connect timeout: de.rwth_aachen.phyphox.\
+BleCompatConnectTest:" - the same defect, one branch over.
+    """
+    lines = [ln.strip() for ln in (out or "").splitlines() if ln.strip()]
+    at = next((i for i, ln in enumerate(lines)
+               if "Exception" in ln or "Error" in ln), None)
+    said = " | ".join(lines[at:at + 3])[:400] if at is not None else ""
+    try:
+        log = evidence_path(dev, args,
+                            f"{scenario['library']}-{scenario['example']}"
+                            f"-connect-failed.txt")
+        with open(log, "w") as f:
+            f.write(out or "")
+        said += f" [full output: {os.path.relpath(log, ROOT)}]"
+    except OSError:
+        pass
+    return said or (out or "")[-300:]
+
+
 def connect_phone(dev, scenario, args, advertised=None):
     """Run the platform's scan-and-connect test on the phone. The UI flow
     (scan, pick the device, accept its experiment) has no remote-API
@@ -658,39 +685,45 @@ def connect_phone(dev, scenario, args, advertised=None):
             # 2026-08-28 reported eight failures as "Error in
             # theDeviceOffersItsExperimentAndItLoads(...):" and nothing
             # else, which is why the whole output is now kept as well.
-            lines = [ln.strip() for ln in out.splitlines() if ln.strip()]
-            at = next((i for i, ln in enumerate(lines)
-                       if "Exception" in ln or "Error" in ln), None)
-            first = " | ".join(lines[at:at + 3])[:400] if at is not None else ""
-            try:
-                log = evidence_path(
-                    dev, args,
-                    f"{scenario['library']}-{scenario['example']}"
-                    f"-connect-failed.txt")
-                with open(log, "w") as f:
-                    f.write(out)
-                first += f" [full output: {os.path.relpath(log, ROOT)}]"
-            except OSError:
-                pass
             return False, ("the connect test never reached its hold: "
-                           + (first or out[-300:])), None
+                           + _instrumentation_cause(dev, scenario, args,
+                                                    out)), None
         if wait_api(dev.base, args.connect_timeout) is None:
             proc.kill()
             # Killing the local adb does NOT stop the instrumentation on
             # the phone; without this it keeps the app alive and the next
             # scenario talks to it.
             sh(dev.adb + ["shell", "am", "force-stop", ANDROID_PACKAGE])
-            out = (proc.communicate()[0] or "")[-300:]
+            out = proc.communicate()[0] or ""
             return False, ("the phone did not reach a loaded experiment "
-                           "within the connect timeout: " + out), None
+                           "within the connect timeout: "
+                           + _instrumentation_cause(dev, scenario, args,
+                                                    out)), None
         return True, "connected", proc
-    r = sh(["xcrun", "devicectl", "device", "process", "launch",
-            "--terminate-existing", "--device", dev.udid, "--",
-            "de.rwth-aachen.physics.phyphox",
-            "-phyphoxBleConnect", name, "-phyphoxRemote",
-            "-phyphoxRemotePort", "80", "-phyphoxAutoConfirm"],
-           timeout=args.connect_timeout)
-    return r.returncode == 0, (r.stderr or r.stdout or "")[-300:], None
+    # device.py's own launcher rather than a second copy of the devicectl
+    # line: it adds -phyphoxRemote, the port and -phyphoxAutoConfirm, and
+    # it carries the fallback for phones devicectl cannot talk to (iOS 17+
+    # only, and the lab's iPhone 8 tops out at 16).
+    if not dev._launch_args(["-phyphoxBleConnect", name]):
+        return False, f"the app did not launch: {dev.last_error}", None
+    # A launch that returns 0 says the app STARTED, nothing more. The
+    # first iOS attempt reported every scenario as connected and then
+    # failed on "no data", which describes the symptom and hides the
+    # cause. -phyphoxBleConnect opens no dialog by design - the app scans
+    # headlessly and the experiment page appearing is the only visible
+    # sign - so the remote API coming up is what "connected" means here,
+    # exactly as on Android.
+    if wait_api(dev.base, args.connect_timeout) is None:
+        return False, (
+            f"the app launched but no experiment was loaded within "
+            f"{args.connect_timeout:.0f} s, so nothing served the remote "
+            f"API. The app logs '-phyphoxBleConnect: no device advertising "
+            f"as {name} turned up within 60 s' to the device console when "
+            f"its scan finds nothing - check there first, then that "
+            f"Bluetooth is permitted for phyphox in Settings (a system "
+            f"prompt, which -phyphoxAutoConfirm deliberately does not "
+            f"touch) and that this build has the seam at all"), None
+    return True, "connected", None
 
 
 def release_phone(dev, handle, args):