test: normalize Windows fixture paths for power sampler

CHANGELOG.md

@@ -2,6 +2,11 @@
 
 ## Unreleased
 
+- Add `scripts/frame-power-sample.sh`, a bounded read-only SSH sampler for
+  battery, CPU, named temperatures, fan and available power rails (issue #52).
+  JSON samples/summaries and CSV exports retain explicit unavailable states;
+  active smoke-test locks stop measurement. No power settings are changed.
+
 - Show saved Android compatibility reports on store search cards and app details.
   Reports refresh in the background, so a stalled database or credential lookup
   cannot delay search. Warnings allow installation; build compatibility blockers

README.md

@@ -44,6 +44,9 @@ Live video of what the lenses show, or of the app panel in use, flat and still h
 **🔋 Battery and status**<br>
 Charge, charging watts and time left, storage, memory, temperature, Wi-Fi, and what's running.
 
+For repeatable read-only battery, power-rail, temperature and fan measurements,
+use the [power and heat sampler](docs/power-and-heat.md).
+
 </td>
 </tr>
 <tr>

docs/evidence/power-sampler-2026-10-24.json

@@ -0,0 +1,149 @@
+{
+  "date": "2026-10-24",
+  "osVersion": "0.5.6",
+  "osBuild": "20261015.6141207",
+  "commands": [
+    "scripts/frame-power-sample.sh --count 3 --interval 1",
+    "scripts/frame-power-sample.sh --count 1 --csv"
+  ],
+  "jsonSampleCount": 3,
+  "elapsedSeconds": [
+    0.078011,
+    1.088542,
+    2.107291
+  ],
+  "stopped": null,
+  "unavailableGroups": [
+    [
+      "proximity"
+    ],
+    [
+      "proximity"
+    ],
+    [
+      "proximity"
+    ]
+  ],
+  "selectedSummary": {
+    "battery.percent": {
+      "unit": "%",
+      "sources": [
+        "/sys/class/power_supply/max1720x_bat_7-36"
+      ],
+      "available": 3,
+      "unavailable": 0,
+      "min": 99,
+      "max": 99,
+      "mean": 99.0,
+      "first": 99,
+      "last": 99
+    },
+    "battery.status": {
+      "unit": "state",
+      "sources": [
+        "/sys/class/power_supply/max1720x_bat_7-36"
+      ],
+      "available": 3,
+      "unavailable": 0,
+      "states": [
+        "Not charging"
+      ]
+    },
+    "battery.tempC": {
+      "unit": "C",
+      "sources": [
+        "/sys/class/power_supply/max1720x_bat_7-36"
+      ],
+      "available": 3,
+      "unavailable": 0,
+      "min": 26.400000000000002,
+      "max": 26.400000000000002,
+      "mean": 26.4,
+      "first": 26.400000000000002,
+      "last": 26.400000000000002
+    },
+    "battery.watts": {
+      "unit": "W",
+      "sources": [
+        "/sys/class/power_supply/max1720x_bat_7-36"
+      ],
+      "available": 3,
+      "unavailable": 0,
+      "min": -0.12,
+      "max": -0.02,
+      "mean": -0.07,
+      "first": -0.02,
+      "last": -0.07
+    },
+    "cpu.percent": {
+      "unit": "%",
+      "sources": [
+        "/proc/stat"
+      ],
+      "available": 2,
+      "unavailable": 1,
+      "min": 8.7,
+      "max": 11.0,
+      "mean": 9.85,
+      "first": 11.0,
+      "last": 8.7
+    },
+    "fan.pwmRaw": {
+      "unit": "raw",
+      "sources": [
+        "/sys/class/hwmon/hwmon50/pwm1"
+      ],
+      "available": 3,
+      "unavailable": 0,
+      "min": 41,
+      "max": 41,
+      "mean": 41.0,
+      "first": 41,
+      "last": 41
+    },
+    "fan.slg4ax46073v.fan1_input": {
+      "unit": "RPM",
+      "sources": [
+        "/sys/class/hwmon/hwmon50/fan1_input"
+      ],
+      "available": 3,
+      "unavailable": 0,
+      "min": 8624,
+      "max": 8638,
+      "mean": 8628.666667,
+      "first": 8638,
+      "last": 8624
+    },
+    "proximity.raw": {
+      "unit": "raw",
+      "sources": [
+        "/sys/bus/iio/devices/iio:device2/in_proximity_raw"
+      ],
+      "available": 0,
+      "unavailable": 3,
+      "states": []
+    },
+    "rail.max34417_9_10.vph.power1": {
+      "unit": "W",
+      "sources": [
+        "/sys/class/hwmon/hwmon53/power1_input"
+      ],
+      "available": 3,
+      "unavailable": 0,
+      "min": 4.656299,
+      "max": 4.804066,
+      "mean": 4.705555,
+      "first": 4.656299,
+      "last": 4.804066
+    }
+  },
+  "csvRows": 92,
+  "csvSummaryMetrics": 91,
+  "csvHasExplicitUnavailable": true,
+  "limits": [
+    "Read-only short transport/parser check; no controlled baseline or worn/load/battery experiment.",
+    "Proximity unavailable; numeric thermistors are not proof of sensor accuracy.",
+    "No settings, services, device files or application state changed; no remote installation.",
+    "No smoke lock at preflight or sampler checks; advisory checks cannot exclude a concurrent lock appearing during a read."
+  ]
+}

docs/power-and-heat.md

@@ -0,0 +1,122 @@
+# Read-only power and heat measurements
+
+Issue [#52](https://github.com/saphid/frame-control/issues/52) starts with
+measurement. `scripts/frame-power-sample.sh` is a bounded, on-demand sampler
+over the existing `ssh frame` alias. It needs Python 3 on both computers and
+an already paired, awake, reachable Frame. It uses strict SSH host-key checking
+and batch mode; it never pairs, prompts for a password or changes SSH security.
+
+```sh
+# Twelve samples, five seconds apart (about 55 seconds), JSON report:
+scripts/frame-power-sample.sh > power.json
+
+# Five-minute observation: samples at 0, 5, ... 300 seconds:
+scripts/frame-power-sample.sh --count 61 --interval 5 > baseline.json
+
+# Long-form CSV samples; JSON summary goes separately to stderr:
+scripts/frame-power-sample.sh --count 12 --interval 5 --csv > power.csv 2> summary.json
+```
+
+Count is limited to 1–720; interval to finite values from 1–60 seconds. These
+are target start-to-start intervals, not guarantees: read latency can delay a
+sample. Wall-clock `time` and monotonic `elapsedSeconds` record actual timing.
+The first sample has no CPU utilization: two valid `/proc/stat` observations
+are required. CPU utilization then covers the interval between observations,
+averaged across the machine, rather than the utilization of one process.
+
+## What it reads
+
+- Battery percentage, driver charging state, signed battery watts and battery
+  temperature, using the same parser as Frame Control's battery details.
+  Positive battery watts mean charging on the Frame fuel gauge; negative means
+  discharge. `Not charging` alone does not prove a charger is connected.
+- CPU utilization from `/proc/stat`; GPU clock from the known Frame devfreq path.
+- Named thermal zones in °C, with zone names retained. A thermal zone is not
+  automatically a CPU sensor; there is no inferred “CPU temperature” or safe
+  temperature threshold.
+- hwmon power channels, labels and driver names in watts. `vph` is the measured
+  system rail, not power at the wall. CPU `apc*` and GPU `gfx` rails are separate
+  readings; do not sum all channels as if they were independent power consumers.
+- Fan RPM and the Frame fan driver's raw `pwm1`. No generic percentage conversion
+  is assumed. The historical Frame driver reported a percent-like value of 41.
+- Named IIO board temperatures, PM8550B input/charge current in amps, and raw
+  VCNL4000 proximity if the account can read it. Raw proximity has no inferred
+  worn/unworn threshold.
+
+Each metric includes its unit, source path and availability state. Missing,
+unreadable or invalid values are JSON `null`, not zero. A missing sensor family
+is also listed in each sample's `unavailableGroups`; CSV adds unavailable group
+rows. Numeric zero remains a valid reading. The OS build is recorded per sample
+when `/etc/os-release` is readable; hostnames, addresses, machine IDs, process
+lists, logs, screenshots and application inventories are not collected.
+
+The JSON report contains raw samples and a summary per metric: available and
+unavailable counts, numeric minimum/maximum/arithmetic mean/first/last, or the
+observed charging states. Means exclude unavailable readings. They are sample
+means, not time-weighted energy or battery-runtime estimates. Different sample
+availability and intervals must be considered when comparing sessions.
+
+Numeric validity does not establish sensor accuracy. Historical readings
+already showed an apparently absent/broken right-display thermistor near
+−16 °C. This firmware also reports one charger-lite die sensor at −60 °C.
+Those raw numbers remain visible for diagnosis; neither should be used to
+infer cooling performance or safety. This tool does not diagnose heat, explain
+a spike, predict battery health, or promise power savings.
+
+## Safety and shared-device use
+
+Only file reads under `/proc`, `/sys` and `/etc/os-release` run on the Frame.
+The Python sources are sent on SSH stdin and not installed on the headset.
+There is no sudo, OpenVR initialization, service call, settings write, process
+control, journal query, wake, suspend or reboot. No daemon, telemetry upload or
+automatic measurement is added. Redirects above write only to your computer.
+The observer itself uses a little CPU and SSH traffic, so label baseline
+conditions and avoid interpreting very small changes as savings.
+
+The sampler checks `/tmp/frame-test.lock` on the computer before SSH, and on
+the Frame before any probe and before each sample. If a smoke session is active,
+it exits 75. A lock appearing mid-run stops the next sample, retains earlier
+samples, sets `stopped`, and exits 75. It never removes or acquires another
+session's lock. This is an advisory check, not an atomic lease: a smoke session
+can start during a file read. Coordinate sessions and defer measurement when
+timing overlaps. It does not block someone else from starting a smoke test.
+
+SSH failures/timeouts return a nonzero exit and an explanation, without
+presenting a zero or an old report as a successful measurement. Fully missing
+sensors can still produce a successful report with explicit unavailable states.
+On a connection failure, partial samples buffered on the headset can be lost.
+
+## Evidence and remaining work
+
+Read-only checks on **2026-10-24**, SteamOS **0.5.6**, build
+**20261015.6141207**, confirmed battery, CPU ticks, thermal zones, rail power,
+fan, GPU clock, board temperatures and charger current through the final
+sampler. Proximity was unavailable. Both JSON and CSV paths were exercised;
+see [the recorded results](evidence/power-sampler-2026-10-24.json).
+No smoke lock was present at the preflight or sampler checks. No settings,
+services, application state or device files were changed. This short run is
+a parser/transport check, not a controlled baseline or a worn-headset test.
+
+The original planning document is in commit `fe132e3` (2026-09-29). It recorded
+an off-head, charging idle baseline of about 4.71 W, CPU zones around 40–45 °C,
+and about 8,350 fan RPM on build 20260925.6191901. Those conditions and firmware
+differ from the current check; comparisons do not establish a regression.
+
+This change completes only the sampler portion of “Plan: leave it on, but
+cheaply.” Controlled worn/home-space, streaming/game load and unplugged
+baselines, and the cause of the 2026-09-28 95 °C spike, remain uninvestigated.
+Quiet mode, compositor changes, CPU/fan/charging changes and remote-wake tests
+are separate work. No controls are offered here. Follow the shared-device
+procedure in [testing.md](testing.md#headset-smoke-test) for future experiments.
+
+Offline validation:
+
+```sh
+python3 -m unittest discover -s tests -p test_power_sample.py -v
+bash -n scripts/frame-power-sample.sh
+python3 -m py_compile scripts/frame_power_sample.py
+```
+
+Fixtures cover units, signed and zero values, missing/malformed/permission-denied
+readings, named/discovered channels, unknown charging state, CPU warmup,
+summary counts, CSV quoting, strict SSH transport and smoke-lock interruption.

docs/testing.md

@@ -12,6 +12,12 @@ A fourth, a SteamOS VM, may come later ([issue #6](https://github.com/saphid/ste
 
 ## Unit tests
 
+The read-only power/heat sampler has fixture and transport tests in
+`tests/test_power_sample.py`. Run
+`python3 -m unittest discover -s tests -p test_power_sample.py -v`.
+See [power-and-heat.md](power-and-heat.md) for sampling, smoke-lock behavior and
+real-device verification limits.
+
 ```sh
 python3 -m unittest discover -s tests
 ```

scripts/frame-power-sample.sh

@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+# Read-only, bounded power/heat sampler. See docs/power-and-heat.md.
+set -euo pipefail
+root=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")/.." && pwd)
+exec python3 "$root/scripts/frame_power_sample.py" "$@"

scripts/frame_power_sample.py

@@ -0,0 +1,211 @@
+"""Bounded read-only Frame measurements; no device files are written.
+
+The host sends this and frame_status.py over one trusted SSH connection. Only
+battery() and CPU tick helpers are reused: no OpenVR, services or analytics.
+"""
+import argparse
+import csv
+import glob
+import io
+import json
+import math
+from pathlib import Path
+import subprocess
+import sys
+import time
+
+LOCK = Path('/tmp/frame-test.lock')
+UNAVAILABLE = 'unavailable: not reported, unreadable or invalid'
+
+
+def read(path):
+    try:
+        return Path(path).read_text().strip()
+    except (OSError, UnicodeError):
+        return None
+
+
+def number(path, scale=1, minimum=None, maximum=None):
+    try:
+        value = int(read(path)) * scale
+        if not math.isfinite(value):
+            return None
+        if minimum is not None and value < minimum or maximum is not None and value > maximum:
+            return None
+        return round(value, 6)
+    except (TypeError, ValueError, OverflowError):
+        return None
+
+
+def snapshot(status, before):
+    if LOCK.exists():
+        raise RuntimeError('Smoke session active (/tmp/frame-test.lock); no sensors read.')
+    ticks = status.cpu_ticks()
+    readings = {}
+
+    def add(key, value, unit, source):
+        readings[key] = {'value': value, 'unit': unit, 'source': source,
+                         'state': 'available' if value is not None else UNAVAILABLE}
+
+    battery = status.battery() or {}
+    for field, unit in (('percent', '%'), ('status', 'state'), ('watts', 'W'),
+                        ('tempC', 'C')):
+        value = battery.get(field)
+        if field == 'status' and value not in ('Charging', 'Discharging', 'Not charging', 'Full'):
+            value = None
+        add('battery.' + field, value, unit, battery.get('source'))
+    add('cpu.percent', status.cpu_percent(before, ticks), '%', '/proc/stat')
+    if before is None:
+        readings['cpu.percent']['state'] = 'unavailable: needs two valid CPU tick samples'
+    add('gpu.clock', number('/sys/class/devfreq/3d00000.gpu/cur_freq', 1e-6, 0),
+        'MHz', '/sys/class/devfreq/3d00000.gpu/cur_freq')
+
+    # Discover by driver name/label, never assume a hwmon index. Keep source
+    # paths and channel numbers to distinguish duplicate labels.
+    for node in sorted(glob.glob('/sys/class/hwmon/hwmon*')):
+        name = read(node + '/name') or Path(node).name
+        for path in sorted(glob.glob(node + '/power*_input')):
+            channel = Path(path).name[:-6]
+            label = read(node + '/' + channel + '_label') or channel
+            add(f'rail.{name}.{label}.{channel}', number(path, 1e-6, 0), 'W', path)
+        for path in sorted(glob.glob(node + '/fan*_input')):
+            add(f'fan.{name}.{Path(path).stem}', number(path, minimum=0), 'RPM', path)
+        # pwm1 on Frame's driver is percent; leave raw to avoid assuming the
+        # generic hwmon 0..255 scale on other drivers or later firmware.
+        if name == 'slg4ax46073v':
+            add('fan.pwmRaw', number(node + '/pwm1', minimum=0), 'raw', node + '/pwm1')
+    for node in sorted(glob.glob('/sys/class/thermal/thermal_zone*')):
+        name = read(node + '/type') or Path(node).name
+        add(f'thermal.{name}.{Path(node).name}', number(node + '/temp', 0.001, -273.15, 200),
+            'C', node + '/temp')
+    for node in sorted(glob.glob('/sys/bus/iio/devices/iio:device*')):
+        for path in sorted(glob.glob(node + '/in_temp_*_input')):
+            add(f'board.{Path(node).name}.{Path(path).stem}', number(path, 0.001, -273.15, 200),
+                'C', path)
+        for field in ('iin', 'ichg'):
+            path = node + '/in_current_pm8550b_' + field + '_fb_input'
+            # Known names, but no fixed IIO index; absent channels are covered
+            # by group availability below.
+            if Path(path).exists():
+                add(f'charger.{Path(node).name}.{field}', number(path, 1e-6), 'A', path)
+        if read(node + '/name') == 'vcnl4000':
+            add('proximity.raw', number(node + '/in_proximity_raw', minimum=0),
+                'raw', node + '/in_proximity_raw')
+    unavailable = [group for group in ('rail', 'fan', 'thermal', 'board', 'charger', 'proximity')
+                   if not any(k.startswith(group + '.') and v['value'] is not None
+                              for k, v in readings.items())]
+    os_info = dict(line.split('=', 1) for line in (read('/etc/os-release') or '').splitlines()
+                   if '=' in line)
+    return {'time': time.time(), 'osBuild': os_info.get('BUILD_ID', '').strip('"') or None,
+            'readings': readings, 'unavailableGroups': unavailable}, ticks
+
+
+def summarize(samples):
+    result = {}
+    keys = sorted({key for sample in samples for key in sample['readings']})
+    for key in keys:
+        rows = [s['readings'][key] for s in samples if key in s['readings']]
+        values = [r['value'] for r in rows if r['value'] is not None]
+        item = {'unit': rows[0]['unit'], 'sources': sorted({r['source'] for r in rows if r['source']}),
+                'available': len(values), 'unavailable': len(samples) - len(values)}
+        if values and all(isinstance(v, (int, float)) for v in values):
+            item.update(min=min(values), max=max(values), mean=round(sum(values) / len(values), 6),
+                        first=values[0], last=values[-1])
+        else:
+            item['states'] = sorted(set(values))
+        result[key] = item
+    return result
+
+
+def collect(status, count, interval):
+    samples, before = [], None
+    started = time.monotonic()
+    stopped = None
+    for index in range(count):
+        if index:
+            time.sleep(max(0, started + index * interval - time.monotonic()))
+        try:
+            sample, before = snapshot(status, before)
+        except RuntimeError as exc:
+            stopped = str(exc)
+            break
+        sample['elapsedSeconds'] = round(time.monotonic() - started, 6)
+        samples.append(sample)
+    return {'schemaVersion': 1, 'requestedSamples': count, 'intervalSeconds': interval,
+            'stopped': stopped, 'samples': samples, 'summary': summarize(samples)}
+
+
+def csv_samples(report):
+    output = io.StringIO(newline='')
+    writer = csv.writer(output)
+    writer.writerow(('time', 'elapsedSeconds', 'metric', 'value', 'unit', 'source', 'state'))
+    for sample in report['samples']:
+        for key, row in sample['readings'].items():
+            # csv quoting does not prevent spreadsheet formulas in labels.
+            def cell(value):
+                return "'" + value if isinstance(value, str) and value.startswith(('=', '+', '-', '@')) else value
+            writer.writerow([cell(v) for v in (sample['time'], sample['elapsedSeconds'], key,
+                                               row['value'], row['unit'], row['source'], row['state'])])
+        for group in sample['unavailableGroups']:
+            writer.writerow((sample['time'], sample['elapsedSeconds'], group, '', '', '', UNAVAILABLE))
+    return output.getvalue()
+
+
+def parser():
+    ap = argparse.ArgumentParser(description=__doc__)
+    ap.add_argument('--count', type=int, default=12, help='samples, 1..720 (default 12)')
+    ap.add_argument('--interval', type=float, default=5, help='seconds, 1..60 (default 5)')
+    ap.add_argument('--csv', action='store_true', help='CSV samples on stdout; JSON summary on stderr')
+    ap.add_argument('--probe', action='store_true', help=argparse.SUPPRESS)
+    return ap
+
+
+def remote_payload():
+    root = Path(__file__).resolve().parents[1]
+    source = (root / 'ui/frame_status.py').read_text()
+    # Executing as a module prevents frame_status.main() from probing unrelated
+    # status. Nothing is installed, cached or logged on the headset.
+    return ('import types, sys\n'
+            'status = types.ModuleType("frame_status")\n'
+            f'exec(compile({source!r}, "frame_status.py", "exec"), status.__dict__)\n'
+            'sys.modules["frame_status"] = status\n' + Path(__file__).read_text())
+
+
+def main(argv=None):
+    ap = parser()
+    args = ap.parse_args(argv)
+    if not 1 <= args.count <= 720 or not math.isfinite(args.interval) or not 1 <= args.interval <= 60:
+        ap.error('count must be 1..720 and interval must be finite, 1..60 seconds')
+    # Also honor a coordinator lock on the computer before opening SSH.
+    if LOCK.exists():
+        print('Smoke session active (/tmp/frame-test.lock); no SSH or sensors accessed.', file=sys.stderr)
+        return 75
+    if args.probe:
+        import frame_status
+        report = collect(frame_status, args.count, args.interval)
+    else:
+        command = ['ssh', '-T', '-o', 'BatchMode=yes', '-o', 'StrictHostKeyChecking=yes',
+                   '-o', 'ConnectTimeout=5', '-o', 'ServerAliveInterval=5',
+                   '-o', 'ServerAliveCountMax=2', 'frame',
+                   'python3', '-', '--probe', '--count', str(args.count), '--interval', str(args.interval)]
+        try:
+            run = subprocess.run(command, input=remote_payload(), text=True, capture_output=True,
+                                 timeout=args.count * args.interval + 30)
+            if run.returncode:
+                print('Read-only sample failed: ' + (run.stderr.strip() or f'SSH exit {run.returncode}'),
+                      file=sys.stderr)
+                return run.returncode
+            report = json.loads(run.stdout)
+        except (OSError, subprocess.TimeoutExpired, ValueError) as exc:
+            print(f'Read-only sample unavailable: {exc}', file=sys.stderr)
+            return 1
+    if args.csv:
+        sys.stdout.write(csv_samples(report))
+        print(json.dumps({k: v for k, v in report.items() if k != 'samples'}, allow_nan=False), file=sys.stderr)
+    else:
+        print(json.dumps(report, allow_nan=False))
+    return 75 if report['stopped'] else 0
+
+
+if __name__ == '__main__':
+    sys.exit(main())

tests/test_power_sample.py

@@ -0,0 +1,209 @@
+"""Power sampler fixtures and SSH transport contract; no real device contact."""
+import sandbox  # noqa: F401
+import contextlib
+import csv
+import importlib.util
+import io
+import json
+from pathlib import Path
+import subprocess
+import sys
+import tempfile
+import unittest
+from unittest import mock
+
+ROOT = Path(__file__).resolve().parents[1]
+spec = importlib.util.spec_from_file_location('power_sample', ROOT / 'scripts/frame_power_sample.py')
+power = importlib.util.module_from_spec(spec)
+spec.loader.exec_module(power)
+sys.path.insert(0, str(ROOT / 'ui'))
+import frame_status as status
+
+
+class Sampler(unittest.TestCase):
+    def patch(self, obj, name, **kwargs):
+        p = mock.patch.object(obj, name, **kwargs)
+        result = p.start()
+        self.addCleanup(p.stop)
+        return result
+
+    def fixture(self, files):
+        # Windows cannot create a directory named iio:device8. Keep the
+        # production sysfs spelling in returned paths while using a portable
+        # name inside this temporary fixture tree.
+        def local_path(path):
+            return self.root / str(path).replace('\\', '/').lstrip('/').replace(':', '__COLON__')
+
+        for path, value in files.items():
+            node = local_path(path)
+            node.parent.mkdir(parents=True, exist_ok=True)
+            node.write_text(str(value))
+        actual_glob = power.glob.glob
+        def paths(pattern):
+            return ['/' + Path(p).relative_to(self.root).as_posix().replace('__COLON__', ':')
+                    for p in actual_glob(str(local_path(pattern)))]
+        actual_read = power.read
+        self.patch(power.glob, 'glob', side_effect=paths)
+        self.patch(power, 'read', side_effect=lambda p: actual_read(str(local_path(str(p)))))
+        self.patch(status, 'read', side_effect=lambda p: actual_read(str(local_path(str(p)))))
+        return local_path
+
+    def setUp(self):
+        self.tmp = tempfile.TemporaryDirectory()
+        self.addCleanup(self.tmp.cleanup)
+        self.root = Path(self.tmp.name)
+        p = mock.patch.object(power, 'LOCK', self.root / 'lock')
+        p.start()
+        self.addCleanup(p.stop)
+
+    def test_real_file_units_zero_signed_battery_and_named_sensors(self):
+        h = '/sys/class/hwmon/hwmon88'
+        b = '/sys/class/power_supply/max1720x_bat_7-36'
+        self.fixture({h + '/name': 'max34417_9_10', h + '/power1_label': 'vph',
+                      h + '/power1_input': '4710000',
+                      '/sys/class/hwmon/hwmon3/name': 'slg4ax46073v',
+                      '/sys/class/hwmon/hwmon3/fan1_input': '0',
+                      '/sys/class/hwmon/hwmon3/pwm1': '41',
+                      '/sys/class/thermal/thermal_zone9/type': 'cpu3_top_thermal',
+                      '/sys/class/thermal/thermal_zone9/temp': '45321',
+                      b + '/type': 'Battery', b + '/capacity': '0', b + '/status': 'Discharging',
+                      b + '/voltage_now': '3800000', b + '/current_now': '-1000000',
+                      '/proc/stat': 'cpu  10 0 0 90 0 0 0 0'})
+        sample, ticks = power.snapshot(status, (80, 80))
+        r = sample['readings']
+        self.assertEqual(r['rail.max34417_9_10.vph.power1']['value'], 4.71)
+        self.assertEqual(r['battery.percent']['value'], 0)
+        self.assertEqual(r['battery.watts']['value'], -3.8)
+        self.assertEqual(r['battery.status']['value'], 'Discharging')
+        self.assertEqual(r['fan.slg4ax46073v.fan1_input']['value'], 0)
+        self.assertEqual(r['fan.pwmRaw']['unit'], 'raw')
+        self.assertEqual(r['thermal.cpu3_top_thermal.thermal_zone9']['value'], 45.321)
+        self.assertEqual(r['cpu.percent']['value'], 50)
+        self.assertEqual(ticks, (100, 90))
+        self.assertEqual(sample['unavailableGroups'], ['board', 'charger', 'proximity'])
+
+    def test_missing_and_invalid_values_remain_unavailable(self):
+        self.fixture({'/sys/class/thermal/thermal_zone0/temp': '999999999',
+                      '/sys/class/hwmon/hwmon2/name': 'fan',
+                      '/sys/class/hwmon/hwmon2/fan1_input': '-1'})
+        sample, ticks = power.snapshot(status, None)
+        self.assertIsNone(ticks)
+        self.assertTrue(all(r['value'] is None for r in sample['readings'].values()))
+        self.assertEqual(len(sample['unavailableGroups']), 6)
+        self.assertIn('two valid CPU', sample['readings']['cpu.percent']['state'])
+
+    def test_permission_error_is_unavailable(self):
+        with mock.patch.object(Path, 'read_text', side_effect=PermissionError):
+            self.assertIsNone(power.number('/unreadable'))
+        for value in ('NaN', 'Infinity', '1.5', '', '9' * 5000):
+            with mock.patch.object(power, 'read', return_value=value):
+                self.assertIsNone(power.number('/invalid'))
+
+    def test_iio_units_and_permission_denied_proximity(self):
+        node = '/sys/bus/iio/devices/iio:device8'
+        local_path = self.fixture({node + '/name': 'vcnl4000',
+                      node + '/in_temp_pcba_at_wifi_input': '37500',
+                      node + '/in_current_pm8550b_iin_fb_input': '241671',
+                      '/etc/os-release': 'BUILD_ID=20261015.6141207\n'})
+        # exists() is used only for optional known charger channels and lock.
+        exists = Path.exists
+        with mock.patch.object(Path, 'exists', lambda p: exists(p) if p == power.LOCK
+                               else exists(local_path(str(p)))):
+            sample, _ = power.snapshot(status, None)
+        self.assertEqual(sample['osBuild'], '20261015.6141207')
+        self.assertEqual(sample['readings']['board.iio:device8.in_temp_pcba_at_wifi_input']['value'], 37.5)
+        self.assertEqual(sample['readings']['charger.iio:device8.iin']['value'], 0.241671)
+        self.assertIsNone(sample['readings']['proximity.raw']['value'])
+        self.assertIn('proximity', sample['unavailableGroups'])
+
+    def test_unknown_charging_state_is_not_claimed(self):
+        self.fixture({})
+        with mock.patch.object(status, 'battery', return_value={'status': 'Unknown', 'percent': 50}):
+            r = power.snapshot(status, None)[0]['readings']
+        self.assertIsNone(r['battery.status']['value'])
+        self.assertEqual(r['battery.percent']['value'], 50)
+
+    def test_smoke_lock_prevents_any_sensor_reads(self):
+        power.LOCK.mkdir()
+        with mock.patch.object(status, 'cpu_ticks') as ticks:
+            with self.assertRaisesRegex(RuntimeError, 'Smoke session'):
+                power.snapshot(status, None)
+        ticks.assert_not_called()
+
+    def test_smoke_lock_appearing_between_samples_stops_and_preserves_partial_report(self):
+        self.fixture({'/proc/stat': 'cpu  10 0 0 90 0 0 0 0'})
+        with mock.patch.object(power.time, 'sleep', side_effect=lambda _: power.LOCK.mkdir()):
+            report = power.collect(status, 3, 1)
+        self.assertEqual(len(report['samples']), 1)
+        self.assertIn('Smoke session', report['stopped'])
+        self.assertEqual(report['requestedSamples'], 3)
+
+    def test_summaries_ignore_missing_values_and_keep_state_changes(self):
+        def row(value, unit='W'):
+            return {'value': value, 'unit': unit, 'source': '/sensor', 'state': 'available'}
+        samples = [{'readings': {'rail': row(0), 'state': row('Charging', 'state')}},
+                   {'readings': {'rail': row(None), 'state': row('Full', 'state')}},
+                   {'readings': {'rail': row(6)}}]
+        summary = power.summarize(samples)
+        self.assertEqual(summary['rail'], dict(unit='W', sources=['/sensor'], available=2,
+                                              unavailable=1, min=0, max=6, mean=3, first=0, last=6))
+        self.assertEqual(summary['state']['states'], ['Charging', 'Full'])
+        self.assertEqual(summary['state']['unavailable'], 1)
+
+    def test_csv_quoting_and_unavailable_groups(self):
+        report = {'samples': [{'time': 1, 'elapsedSeconds': 0,
+                              'readings': {'fan,test': {'value': -3.8, 'unit': 'W',
+                                                       'source': '=formula', 'state': 'available'}},
+                              'unavailableGroups': ['thermal']}]}
+        rows = list(csv.reader(io.StringIO(power.csv_samples(report))))
+        self.assertEqual(rows[1][2:6], ['fan,test', '-3.8', 'W', "'=formula"])
+        self.assertEqual(rows[2][-1], power.UNAVAILABLE)
+
+    def test_bounded_arguments_rejected_before_ssh(self):
+        for args in (['--count', '0'], ['--count', '721'], ['--interval', 'nan'],
+                     ['--interval', 'inf'], ['--interval', '0.5'], ['--interval', '61']):
+            with mock.patch.object(power.subprocess, 'run') as run, contextlib.redirect_stderr(io.StringIO()):
+                with self.assertRaises(SystemExit):
+                    power.main(args)
+            run.assert_not_called()
+
+    def test_local_lock_prevents_ssh(self):
+        power.LOCK.mkdir()
+        with mock.patch.object(power.subprocess, 'run') as run, contextlib.redirect_stderr(io.StringIO()):
+            self.assertEqual(power.main([]), 75)
+        run.assert_not_called()
+
+    def test_ssh_payload_runs_as_module_and_outputs_report(self):
+        report = dict(samples=[], summary={}, stopped=None)
+        def ssh(command, **kwargs):
+            self.assertIn('BatchMode=yes', command)
+            self.assertIn('StrictHostKeyChecking=yes', command)
+            self.assertIn('frame', command)
+            self.assertEqual(command[-4:], ['--count', '2', '--interval', '1.0'])
+            # Execute the exact transmitted source, with main suppressed. Its
+            # frame_status module must be importable without running status().
+            namespace = {'__name__': 'payload_test'}
+            with mock.patch.dict(sys.modules):
+                exec(compile(kwargs['input'], '<ssh-stdin>', 'exec'), namespace)
+                remote = sys.modules['frame_status']
+                self.assertTrue(callable(remote.battery))
+                with mock.patch.object(remote, 'status', side_effect=AssertionError('full status forbidden')), \
+                     mock.patch.object(remote, 'battery', return_value=None), \
+                     mock.patch.object(remote, 'cpu_ticks', return_value=(100, 90)), \
+                     mock.patch.object(namespace['glob'], 'glob', return_value=[]), \
+                     mock.patch.object(namespace['Path'], 'exists', return_value=False):
+                    report.update(namespace['collect'](remote, 1, 1))
+            return subprocess.CompletedProcess(command, 0, json.dumps(report), '')
+        output = io.StringIO()
+        with mock.patch.object(power.subprocess, 'run', side_effect=ssh), contextlib.redirect_stdout(output):
+            self.assertEqual(power.main(['--count', '2', '--interval', '1']), 0)
+        self.assertEqual(len(json.loads(output.getvalue())['samples']), 1)
+
+    def test_ssh_failures_are_not_measurements(self):
+        for result in (subprocess.CompletedProcess([], 255, '', 'offline'),
+                       subprocess.CompletedProcess([], 0, 'bad json', '')):
+            output = io.StringIO()
+            with mock.patch.object(power.subprocess, 'run', return_value=result), \
+                 contextlib.redirect_stdout(output), contextlib.redirect_stderr(io.StringIO()):
+                self.assertNotEqual(power.main([]), 0)
+            self.assertEqual(output.getvalue(), '')