App 2.41.0, server 2.9.0: recordings reach the server

A finished signal recording goes to an outbox and is sent gzipped with
the car's token (PUT /v1/logs/{name}); the service retries every 2
minutes while the car is offline. The server keeps the newest 200 on a
new volume (LOGS_DIR); reading takes a token of its own (LOGS_TOKEN).
fetch-logs in the dev shell fetches new ones into logs/.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LhzAVaUyqcw5PkGjz4mWW6

.gitignore

@@ -41,3 +41,7 @@ mise.local.toml
 
 # CarPlay diagnostic exports: vendor software, never committed
 /dump/
+
+# The car's own recordings (fetch-logs, or copied off a USB stick): its data, not the code's.
+/logs/
+/signal-recording-*.txt

AGENTS.md

@@ -21,7 +21,8 @@ MG4 head unit (Android 9, AAOS, MT2712)
 - **server/** — Go 1.27 API at `https://car.k8s.stinnesbeck.com`: stores telemetry, consumption
   and charging in InfluxDB, pairs cars by QR code, carries settings typed on a phone, relays
   app releases from the private forge, and serves the roads for the Grid's map from
-  OpenStreetMap vector tiles (OpenFreeMap), fetched per tile on demand and cached on a volume. It does **not** talk to ABRP. See `server/README.md`.
+  OpenStreetMap vector tiles (OpenFreeMap), fetched per tile on demand and cached on a volume, and keeps the signal recordings the car sends
+  (read with their own token, `fetch-logs`). It does **not** talk to ABRP. See `server/README.md`.
 - **k8s/** — plain Kubernetes manifests (InfluxDB, server, Grafana with three provisioned
   dashboards, Traefik routes). See `k8s/README.md`.
 - **EVHardware/** — vendored shared vehicle layer (PolyForm Noncommercial, see `LICENSE.md`).
@@ -81,7 +82,7 @@ Repository: `ssh://git@git.stinnesbeck.com:2222/nils/mg4.git` (remote `origin`),
 | Live data | on/off, ABRP API key and user token, upload frequency |
 | Server | URL, pairing by QR, ingest token, installation ID (read-only), config import |
 | Settings | drive mode (Eco, Normal, Sport, Snow, Custom; the lit one is what the car reports; changes only in P at a standstill, `DriveModeWrite`; "Set at start" sets the last confirmed choice again when the service starts with the head unit), full screen, voice key, Overview style with the accent colour beside it (offered only for styles drawn in it, `OverviewStyle.usesAccent`; Retro, Terminal, Grid (and Grid with map, sharing Grid's choice) and Visor add "Original" for their own palette, `hasOriginal`), tyre unit, battery and charging price (one card on wide screens), version, update check, install from USB, About |
-| Logs | signal recorder (`SignalRecorder`/`SignalRecording`: every property and vendor getter via `VendorSurfaceProbe.capture`, again and again for 3 minutes, plus change events of the driver-assistance block it subscribes to, `EVHardware.listenToProperties` with `AssistBlock`, and steering-wheel key broadcasts; lists what changed, rarest first; saved to the app and a USB stick; how to find where the car publishes something), update log (every install step, with the platform's words), upload log |
+| Logs | signal recorder (`SignalRecorder`/`SignalRecording`: every property and vendor getter via `VendorSurfaceProbe.capture`, again and again for 3 minutes, plus change events of the driver-assistance block it subscribes to, `EVHardware.listenToProperties` with `AssistBlock`, and steering-wheel key broadcasts; lists what changed, rarest first; saved to the app, a USB stick and the server, through `LogOutbox`, which sends it again later when the car is offline; how to find where the car publishes something), update log (every install step, with the platform's words), upload log |
 
 Key classes (`app/src/main/java/com/evsuite/abrp/`): `AbrpUploadService` (foreground service,
 15 s tick), `TelemetryUploader` (+ `TelemetryQueue`, persisted), `TelemetryPayload` (server
@@ -110,6 +111,7 @@ nix develop                                   # JDK 21, Android SDK, Go
 ./gradlew testStableDebugUnitTest testUnstableDebugUnitTest lintStableDebug
 build-car                                     # build/car/NilsMG4-unstable-<version>.apk + .sha256
 publish-car                                   # pre-release car-<version> on the forge (needs a token)
+fetch-logs                                    # the car's recordings from the server into logs/ (needs LOGS_TOKEN)
 cd server && go vet ./... && go test ./... && govulncheck ./...
 ```
 

EVHardware/lib/src/main/java/com/evsuite/hardware/EVHardware.kt

@@ -324,6 +324,10 @@ object EVHardware {
     // Listening to properties (the app's signal recorder) — read only
     // -------------------------------------------------------------------------
 
+    /** Why the last [listenToProperties] returned null, in a few words; null after a success. */
+    @Volatile var listenProblem: String? = null
+        private set
+
     /** A subscription made by [listenToProperties]; [close] ends it. */
     class PropertyListening internal constructor(
         /** Properties subscribed to, and those the car service refused. */
@@ -342,19 +346,44 @@ object EVHardware {
      * may fill a property from the car network only while someone listens, so a poll alone can
      * read its default. ON_CHANGE properties are asked for every change, CONTINUOUS ones for
      * 1 Hz within their limits. Read only: nothing is set. Null when there is no
-     * CarPropertyManager or no way to subscribe; [PropertyListening.close] unsubscribes.
+     * CarPropertyManager or no way to subscribe, with the reason in [listenProblem];
+     * [PropertyListening.close] unsubscribes.
+     *
+     * Android 9's car library (the MG4's) names the calls `registerListener(CarPropertyEventListener,
+     * int, float)` and `unregisterListener`; Android 10 renamed them `registerCallback` and
+     * `unregisterCallback`. Both are looked for. Unsubscribing goes property by property: the
+     * one-argument `unregisterListener` of Android 9 removes entries from the list it walks and so
+     * leaves every other property subscribed.
      */
     fun listenToProperties(admit: (Int) -> Boolean, onEvent: (Int, Int, String) -> Unit): PropertyListening? {
-        val cpm = sCarPropertyManager ?: return null
+        listenProblem = null
+        val cpm = sCarPropertyManager ?: run {
+            listenProblem = "no car service"
+            return null
+        }
         return try {
-            val register = cpm.javaClass.methods.firstOrNull {
-                it.name == "registerCallback" && it.parameterCount == 3
-            } ?: return null
-            val unregister = cpm.javaClass.methods.firstOrNull {
-                it.name == "unregisterCallback" && it.parameterCount == 1
+            val methods = cpm.javaClass.methods
+            val register = methods.firstOrNull {
+                (it.name == "registerListener" || it.name == "registerCallback") && it.parameterCount == 3 &&
+                    it.parameterTypes[1] == Int::class.javaPrimitiveType &&
+                    it.parameterTypes[2] == Float::class.javaPrimitiveType
+            } ?: run {
+                listenProblem = "no way to subscribe"
+                return null
             }
             val callbackType = register.parameterTypes[0]
-            if (!callbackType.isInterface) return null
+            val unregister = methods.firstOrNull {
+                it.name == register.name.replaceFirst("register", "unregister") && it.parameterCount == 2 &&
+                    it.parameterTypes[0] == callbackType && it.parameterTypes[1] == Int::class.javaPrimitiveType
+            }
+            val unregisterAll = methods.firstOrNull {
+                it.name == register.name.replaceFirst("register", "unregister") && it.parameterCount == 1 &&
+                    it.parameterTypes[0] == callbackType
+            }
+            if (!callbackType.isInterface) {
+                listenProblem = "unexpected listener type ${callbackType.simpleName}"
+                return null
+            }
             val proxy = Proxy.newProxyInstance(callbackType.classLoader, arrayOf(callbackType)) { self, method, args ->
                 when (method.name) {
                     "onChangeEvent" -> {
@@ -385,7 +414,7 @@ object EVHardware {
                 }
             }
             val configs = cpm.javaClass.getMethod("getPropertyList").invoke(cpm) as? List<*> ?: return null
-            var subscribed = 0
+            val subscribedIds = ArrayList<Int>()
             var refused = 0
             for (config in configs) {
                 if (config == null) continue
@@ -399,21 +428,31 @@ object EVHardware {
                     1f.coerceIn(min, maxOf(min, max))
                 }
                 try {
-                    if (register.invoke(cpm, proxy, id, rate) == false) refused++ else subscribed++
+                    if (register.invoke(cpm, proxy, id, rate) == false) refused++ else subscribedIds.add(id)
                 } catch (e: Exception) {
                     refused++
                     AppLogger.d(TAG, "listen: 0x%08X refused: %s".format(id, e.readFailureReason()))
                 }
             }
-            AppLogger.i(TAG, "listening to $subscribed properties ($refused refused)")
-            PropertyListening(subscribed, refused) {
-                try {
-                    unregister?.invoke(cpm, proxy)
-                } catch (e: Exception) {
-                    AppLogger.d(TAG, "listen: unsubscribe failed: ${e.readFailureReason()}")
+            AppLogger.i(TAG, "listening to ${subscribedIds.size} properties ($refused refused) via ${register.name}")
+            PropertyListening(subscribedIds.size, refused) {
+                for (id in subscribedIds) {
+                    try {
+                        if (unregister != null) unregister.invoke(cpm, proxy, id)
+                    } catch (e: Exception) {
+                        AppLogger.d(TAG, "listen: unsubscribe 0x%08X failed: %s".format(id, e.readFailureReason()))
+                    }
+                }
+                if (unregister == null) {
+                    try {
+                        unregisterAll?.invoke(cpm, proxy)
+                    } catch (e: Exception) {
+                        AppLogger.d(TAG, "listen: unsubscribe failed: ${e.readFailureReason()}")
+                    }
                 }
             }
         } catch (e: Exception) {
+            listenProblem = e.readFailureReason()
             AppLogger.w(TAG, "listenToProperties: ${e.readFailureReason()}")
             null
         }

EVHardware/lib/src/test/java/com/evsuite/hardware/PropertyListeningTest.kt

@@ -0,0 +1,105 @@
+package com.evsuite.hardware
+
+import org.junit.After
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNotNull
+import org.junit.Assert.assertNull
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+class PropertyListeningTest {
+
+    class Config(val propertyId: Int, val changeMode: Int, val minSampleRate: Float, val maxSampleRate: Float)
+    class Value(val propertyId: Int, val areaId: Int, val value: Any)
+
+    /** Shaped like Android 9's CarPropertyManager, the car's: registerListener, and an
+     *  unregisterListener(listener) that skips every other property as the car's does. */
+    class Android9Manager(private val configs: List<Config>) {
+        interface CarPropertyEventListener {
+            fun onChangeEvent(value: Any?)
+            fun onErrorEvent(propertyId: Int, areaId: Int)
+        }
+
+        val active = LinkedHashMap<Int, MutableList<CarPropertyEventListener>>()
+        val rates = HashMap<Int, Float>()
+
+        fun getPropertyList(): List<Config> = configs
+
+        fun registerListener(listener: CarPropertyEventListener, propertyId: Int, rate: Float): Boolean {
+            active.getOrPut(propertyId) { ArrayList() }.add(listener)
+            rates[propertyId] = rate
+            return true
+        }
+
+        fun unregisterListener(listener: CarPropertyEventListener) {
+            val ids = active.keys.toMutableList()
+            var i = 0
+            while (i < ids.size) {
+                unregisterListener(listener, ids[i])
+                if (active[ids[i]] == null) ids.removeAt(i) // as SparseArray.remove under keyAt(i)
+                i++
+            }
+        }
+
+        fun unregisterListener(listener: CarPropertyEventListener, propertyId: Int) {
+            val list = active[propertyId] ?: return
+            list.remove(listener)
+            if (list.isEmpty()) active.remove(propertyId)
+        }
+
+        fun fire(propertyId: Int, value: Any) {
+            active[propertyId]?.toList()?.forEach { it.onChangeEvent(Value(propertyId, 0x01000000, value)) }
+        }
+    }
+
+    class NoListeners {
+        fun getPropertyList(): List<Config> = emptyList()
+    }
+
+    private val field = EVHardware::class.java.getDeclaredField("sCarPropertyManager").apply { isAccessible = true }
+
+    @After
+    fun reset() = field.set(null, null)
+
+    @Test
+    fun `subscribes through Android 9's registerListener and unsubscribes every property`() {
+        val manager = Android9Manager(listOf(
+            Config(0x2160A15B, 1, 0f, 0f),     // in the block, on change
+            Config(0x2140A15A, 1, 0f, 0f),
+            Config(0x2160A1A3, 2, 0f, 10f),    // continuous
+            Config(0x2140A101, 1, 0f, 0f),
+            Config(0x11400400, 1, 0f, 0f),     // outside the block
+        ))
+        field.set(null, manager)
+        val heard = ArrayList<String>()
+
+        val listening = EVHardware.listenToProperties(AssistBlock::contains) { id, area, value ->
+            heard += "%08X/%d=%s".format(id, area, value)
+        }
+
+        assertNotNull(EVHardware.listenProblem, listening)
+        assertEquals(4, listening!!.subscribed)
+        assertEquals(0, listening.refused)
+        assertEquals(setOf(0x2160A15B, 0x2140A15A, 0x2160A1A3, 0x2140A101), manager.active.keys)
+        assertEquals(0f, manager.rates[0x2160A15B])
+        assertEquals(1f, manager.rates[0x2160A1A3])
+
+        manager.fire(0x2160A15B, 90f)
+        assertEquals(1, heard.size)
+        assertTrue(heard[0], heard[0].startsWith("2160A15B/16777216="))
+
+        listening.close()
+        assertTrue(manager.active.toString(), manager.active.isEmpty())
+    }
+
+    @Test
+    fun `says why when there is no way to subscribe`() {
+        field.set(null, NoListeners())
+        assertNull(EVHardware.listenToProperties(AssistBlock::contains) { _, _, _ -> })
+        assertEquals("no way to subscribe", EVHardware.listenProblem)
+
+        field.set(null, null)
+        assertNull(EVHardware.listenToProperties(AssistBlock::contains) { _, _, _ -> })
+        assertEquals("no car service", EVHardware.listenProblem)
+    }
+}

README.md

@@ -95,7 +95,7 @@ with the server using a token of its own, obtained by pairing with a phone (belo
 | **Live data** | Live data on/off, ABRP credentials for sending directly from the car, upload frequency |
 | **Server** | Server URL, pairing by QR code, ingest token, installation ID, config import |
 | **Settings** | Full screen, voice key, Overview style and accent colour, tyre pressure unit; drive mode (Eco, Normal, Sport, Snow, Custom: changes only in P at a standstill; the highlighted one is what the car reports; with "Set at start" the last confirmed choice is set again when the car starts, while it is still in P); battery (manual SoH, usable capacity) and charging price; entry on the phone; version, update check, install from USB stick, About |
-| **Logs** | Signal recorder (records every value the head unit offers for 3 minutes, listens to the driver-assistance values for every change they report, and lists what changed, to find where the car publishes something; saved to a USB stick too), update log (every install step), upload log |
+| **Logs** | Signal recorder (records every value the head unit offers for 3 minutes, listens to the driver-assistance values for every change they report, and lists what changed, to find where the car publishes something; sent to your server, and saved to a USB stick too), update log (every install step), upload log |
 
 - **Opening the app:** the MG4 launcher does not list third-party apps. **Double-press the
   voice key** on the steering wheel and the app comes to the front (switch on the Settings

SPECS.md

@@ -140,6 +140,41 @@ tyre pressures, GPS (lat, lon, elevation, heading) and the is_* flags. It does *
   confirmed car facts, app structure, UI conventions, build/test/ship, documents. It replaces
   upstream's EVABRPUploader text. The test emulator is now in the flake: `nix run .#car-emulator`
   (Android 9 AOSP at 1920×720, 160 dpi; the car build installs as the system user — checked).
+- 2026-10-27 — App 2.41.0, server 2.9.0: **recordings reach the server** (owner: "can we make
+  it so that we can upload the logs to an endpoint in the server, and you can get the logs from
+  there? that way i don't have to carry a usb stick"). A finished signal recording goes to
+  `files/log-outbox` (`LogOutbox`, at most 10 waiting) and is sent at once, gzipped, with the car's
+  token: `PUT /v1/logs/{name}`. Offline, 401 (not paired yet), 404 (a server without logs), 408,
+  429 or 5xx keep it, and the service's tick sends it again, at most every 2 minutes; any other
+  refusal drops it. The Logs tab says "Sent to the server." or how many wait and why. Server
+  (`logs.go`): `LOGS_DIR` on a new 1Gi volume `mg4-server-logs`, the newest 200 files and none
+  older than 180 days, names as the app's only, up to 2 MB sent and 8 MB unpacked, UTF-8 only; the
+  same name replaces itself. Reading (`GET /v1/logs`, `GET /v1/logs/{name}`) takes `LOGS_TOKEN`, a
+  new optional Secret value that must differ from `INGEST_TOKEN`; the car's token cannot read, the
+  read token cannot write. `fetch-logs` in the dev shell fetches the new ones into `logs/`
+  (gitignored, as are the recordings copied into the checkout's top folder), token from
+  `~/.config/nilsmg4/logs-token`. Tested: server unit tests (both tokens, refusals, pruning,
+  config); the real server code in a harness on this machine took the 08:52 recording gzipped as
+  the app sends it (204), refused the car's token for reading (401), and `fetch-logs` brought it
+  back byte for byte, once. The app's own sending could not be pointed at that harness (the app
+  takes https only); on the emulator the recording lands in the outbox and the Logs tab says it
+  waits. Not tried on the car.
+- 2026-10-27 — App 2.40.4 published (`car-2.40.4`).
+- 2026-10-27 — App 2.40.4: **the recorder's listening works on Android 9**. Both recordings
+  from the car (08:49 and 08:52, 2.40.3) said "listening to the assistance properties: not
+  possible": `listenToProperties` looked only for `registerCallback`, Android 10's name; the car's
+  car library (Android 9) has `registerListener(CarPropertyEventListener, int, float)` and
+  `unregisterListener`, as the app's `CarPropertyAdapter` already knew. It now takes either, and
+  unsubscribes property by property (Android 9's one-argument `unregisterListener` removes
+  entries from the list it walks and would leave every other property subscribed). A failure now
+  says why (`EVHardware.listenProblem`: no car service, no way to subscribe, or the exception).
+  Tested with a stand-in manager of Android 9's shape (`PropertyListeningTest`). Correction to
+  2.40.3: the ignition listener it was compared with also looks only for `registerCallback`, so
+  it most likely never subscribes on the car either (it reads the state once at start); left as
+  it is. What the polled part of the two recordings shows of the block: `0x2160A15B` (by name
+  the target speed) 0.0 throughout; `0x2140A15A` between 3 and 7 every few captures;
+  `0x2160A1A3`/`0x2160A1A4` counting up by 0.1; speeds 8–33 km/h. Not tried on the car.
+- 2026-10-27 — App 2.40.3 published (`car-2.40.3`; also carries 2.40.1 and 2.40.2).
 - 2026-10-27 — App 2.40.3: **the signal recorder listens** (owner: "is there really nothing we
   can do about the readout of the cruise control set point"). The 2.32.0 recording only polled.
   The head unit's `CarAdvancedAssistedDrivingManager` never polls its 108 `AAD_*` properties: it

app/build.gradle

@@ -34,8 +34,8 @@ android {
         applicationId "com.stinnesbeck.nilsmg4"
         minSdk 27
         targetSdk 36
-        versionCode 148
-        versionName "2.40.3"
+        versionCode 150
+        versionName "2.41.0"
 
         // Nothing about the server ships in the APK: its URL and ingest token are entered in
         // the app's Server tab (ServerConfig), and the database is only reachable by the server.

app/src/main/java/com/evsuite/abrp/AbrpUploadService.java

@@ -223,6 +223,7 @@ public class AbrpUploadService extends Service {
         consumptionTracker.sample(vehicle);
         chargeSessionTracker.sample(vehicle);
         consumptionCloudClient.syncIfDue(consumptionTracker, chargeSessionTracker, sampleMs);
+        LogOutbox.sendIfDue(this); // recordings the car could not send when they ended
 
         UploadSettings settings = UploadSettings.from(prefs);
         // Live data goes to the server, to ABRP directly, or both; with neither set up there is

app/src/main/java/com/evsuite/abrp/LogOutbox.java

@@ -0,0 +1,156 @@
+package com.evsuite.abrp;
+
+import android.content.Context;
+import android.util.Log;
+
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.regex.Pattern;
+import java.util.zip.GZIPOutputStream;
+
+/**
+ * Files from the Logs tab (signal recordings) on their way to the car server, so they reach the
+ * owner without a USB stick: kept in {@code files/log-outbox} until the server has them
+ * ({@code PUT /v1/logs/{name}}, gzip, the ingest token in the header), sent at once and, when
+ * that fails, again from the service's tick, at most every {@link #RETRY_MS}. At most
+ * {@link #MAX_FILES} wait; the oldest goes first. Names are the app's own and say nothing about
+ * where the car is.
+ */
+final class LogOutbox {
+
+    static final String DIR = "log-outbox";
+    static final int MAX_FILES = 10;
+    static final long RETRY_MS = 2 * 60_000L;
+    private static final String TAG = "EVABRP.LogOutbox";
+    /** As the server accepts them. */
+    private static final Pattern NAME = Pattern.compile("[a-z0-9][a-z0-9-]{0,79}\\.txt");
+
+    /** What to do with a file after the server's answer. */
+    enum Outcome { SENT, DROP, KEEP }
+
+    private static long lastFailureMs;
+    private static String lastResult;
+
+    private LogOutbox() {}
+
+    /** SENT for a 2xx; KEEP for what may pass later (no answer, 401 before pairing, 408, 429,
+     *  5xx, and a 404 from a server without logs yet); DROP for any other refusal. */
+    static Outcome outcome(int status) {
+        if (status >= 200 && status < 300) return Outcome.SENT;
+        if (status <= 0 || status == 401 || status == 404 || status == 408 || status == 429 || status >= 500) {
+            return Outcome.KEEP;
+        }
+        return Outcome.DROP;
+    }
+
+    static boolean validName(String name) {
+        return name != null && NAME.matcher(name).matches();
+    }
+
+    /** The names to remove so that at most [max] remain: the oldest (by name, which starts
+     *  with what they are and ends in the time) beyond the newest [max]. */
+    static List<String> surplus(List<String> names, int max) {
+        List<String> sorted = new ArrayList<>(names);
+        Collections.sort(sorted);
+        return sorted.size() <= max ? Collections.emptyList() : sorted.subList(0, sorted.size() - max);
+    }
+
+    /** Puts [text] in the outbox as [name]; false when it could not be written. */
+    static synchronized boolean add(Context context, String name, List<String> text) {
+        if (!validName(name)) return false;
+        File dir = new File(context.getFilesDir(), DIR);
+        if (!dir.isDirectory() && !dir.mkdirs()) return false;
+        File tmp = new File(dir, name + ".tmp");
+        try (Writer out = new OutputStreamWriter(new FileOutputStream(tmp), StandardCharsets.UTF_8)) {
+            for (String line : text) out.write(line + "\n");
+        } catch (Exception e) {
+            tmp.delete();
+            return false;
+        }
+        if (!tmp.renameTo(new File(dir, name))) {
+            tmp.delete();
+            return false;
+        }
+        for (String old : surplus(waiting(dir), MAX_FILES)) new File(dir, old).delete();
+        lastFailureMs = 0; // something new: try at once
+        return true;
+    }
+
+    /** Sends what waits, unless the last attempt failed less than {@link #RETRY_MS} ago. Blocking:
+     *  call it off the main thread. */
+    static void sendIfDue(Context context) {
+        synchronized (LogOutbox.class) {
+            if (lastFailureMs != 0 && System.currentTimeMillis() - lastFailureMs < RETRY_MS) return;
+        }
+        send(context);
+    }
+
+    /** Sends every waiting file, oldest first, until one fails. Blocking. */
+    static synchronized void send(Context context) {
+        File dir = new File(context.getFilesDir(), DIR);
+        List<String> names = waiting(dir);
+        if (names.isEmpty()) return;
+        ServerConfig config = ServerConfig.get(context);
+        if (!config.isConfigured()) {
+            lastResult = "no server set up";
+            lastFailureMs = System.currentTimeMillis();
+            return;
+        }
+        Collections.sort(names);
+        for (String name : names) {
+            File file = new File(dir, name);
+            int status;
+            try {
+                byte[] body = gzip(Files.readAllBytes(file.toPath()));
+                status = ServerHttp.send("PUT", config.url + "/v1/logs/" + name, "Bearer " + config.token,
+                        "text/plain; charset=utf-8", "gzip", body).status;
+            } catch (Exception e) {
+                Log.w(TAG, "Log not sent: " + e.getClass().getSimpleName());
+                status = 0;
+            }
+            Outcome outcome = outcome(status);
+            if (outcome == Outcome.KEEP) {
+                lastResult = status == 0 ? "server not reached" : "server answered " + status;
+                lastFailureMs = System.currentTimeMillis();
+                return;
+            }
+            file.delete();
+            lastResult = outcome == Outcome.SENT ? "sent" : "refused by the server (" + status + ")";
+            Log.i(TAG, "Log " + name + ": " + lastResult);
+        }
+        lastFailureMs = 0;
+    }
+
+    /** For the Logs tab: whether the last file reached the server, or why not yet. */
+    static synchronized String status(Context context) {
+        int waiting = waiting(new File(context.getFilesDir(), DIR)).size();
+        if (waiting == 0) return lastResult == null ? null : "sent".equals(lastResult)
+                ? context.getString(R.string.log_outbox_sent) : lastResult;
+        return context.getString(R.string.log_outbox_waiting, waiting, lastResult == null ? "…" : lastResult);
+    }
+
+    private static List<String> waiting(File dir) {
+        String[] names = dir.list();
+        List<String> out = new ArrayList<>();
+        if (names == null) return out;
+        for (String n : Arrays.asList(names)) if (validName(n)) out.add(n);
+        return out;
+    }
+
+    private static byte[] gzip(byte[] data) throws java.io.IOException {
+        ByteArrayOutputStream buf = new ByteArrayOutputStream(data.length / 4 + 64);
+        try (GZIPOutputStream z = new GZIPOutputStream(buf)) {
+            z.write(data);
+        }
+        return buf.toByteArray();
+    }
+}

app/src/main/java/com/evsuite/abrp/ServerHttp.java

@@ -59,6 +59,12 @@ final class ServerHttp {
      */
     static Response send(String method, String url, String authorization, String contentType, byte[] body)
             throws Exception {
+        return send(method, url, authorization, contentType, null, body);
+    }
+
+    /** As above, with a {@code Content-Encoding} ({@code "gzip"}) for the body, or null. */
+    static Response send(String method, String url, String authorization, String contentType,
+            String contentEncoding, byte[] body) throws Exception {
         HttpURLConnection connection = (HttpURLConnection) new URL(url).openConnection();
         try {
             connection.setRequestMethod(method);
@@ -69,6 +75,7 @@ final class ServerHttp {
                 connection.setDoOutput(true);
                 connection.setFixedLengthStreamingMode(body.length);
                 connection.setRequestProperty("Content-Type", contentType);
+                if (contentEncoding != null) connection.setRequestProperty("Content-Encoding", contentEncoding);
                 try (OutputStream out = connection.getOutputStream()) { out.write(body); }
             }
             int status = connection.getResponseCode();

app/src/main/java/com/evsuite/abrp/SignalRecorder.java

@@ -39,8 +39,8 @@ import java.util.Map;
  * A full capture is far heavier than the Overview's reading, so the next one waits at least
  * {@link #MIN_INTERVAL_MS} and at least as long as the last one took: the recorder uses at most
  * half the time. It runs on its own thread, on after the app leaves the screen (the service
- * keeps the process), and stops by itself. At the end the recording goes to the app's storage
- * and to the app's folder on every USB stick plugged in.
+ * keeps the process), and stops by itself. At the end the recording goes to the app's storage,
+ * to the app's folder on every USB stick plugged in, and to the car server ({@link LogOutbox}).
  */
 final class SignalRecorder {
 
@@ -103,7 +103,8 @@ final class SignalRecorder {
             rec.note(System.currentTimeMillis(), "listening failed: " + t.getClass().getSimpleName());
         }
         rec.note(System.currentTimeMillis(), listening == null
-                ? "listening to the assistance properties: not possible (no car service)"
+                ? "listening to the assistance properties: not possible ("
+                        + EVHardware.INSTANCE.getListenProblem() + ")"
                 : "listening to " + listening.getSubscribed() + " assistance properties ("
                         + listening.getRefused() + " refused)");
         try {
@@ -180,6 +181,12 @@ final class SignalRecorder {
                 // A volume that cannot say what it is gets nothing.
             }
         }
+        // And to the server, so it reaches the owner without a stick; the service sends it again
+        // later when the car is offline now.
+        if (LogOutbox.add(app, name, text)) {
+            LogOutbox.send(app);
+            places.add("for the server");
+        }
         return places.isEmpty() ? "not saved" : "saved: " + String.join(", ", places);
     }
 
@@ -203,6 +210,8 @@ final class SignalRecorder {
         } else {
             out.add(context.getString(R.string.signal_recorder_done, SignalRecording.time(startedMs),
                     recording.captures(), recording.events(), result == null ? "…" : result));
+            String sent = LogOutbox.status(context);
+            if (sent != null) out.add(sent);
         }
         // Steering-wheel keys and the like first: few, and each one a lead.
         List<String> notes = recording.notes();

app/src/main/res/values/strings.xml

@@ -223,11 +223,13 @@
     <string name="drive_mode_unreadable">Not changed: speed or gear unreadable.</string>
     <string name="drive_mode_unknown">an unknown mode (%1$s)</string>
     <string name="label_signal_recorder">Signal recorder</string>
-    <string name="signal_recorder_hint">Records every value the head unit offers for 3 minutes, listens to the driver-assistance properties for every change they report, and notes the steering-wheel keys; then lists what changed, the rarest first. To find a signal: start it, note the times you switch the feature on and off or change it, and look for the values that changed then. With a USB stick plugged in, the whole recording is saved on it too (Android/data/…/files).</string>
+    <string name="signal_recorder_hint">Records every value the head unit offers for 3 minutes, listens to the driver-assistance properties for every change they report, and notes the steering-wheel keys; then lists what changed, the rarest first. To find a signal: start it, note the times you switch the feature on and off or change it, and look for the values that changed then. The whole recording goes to your server (later, if the car is offline), and with a USB stick plugged in it is saved on it too (Android/data/…/files).</string>
     <string name="btn_signal_record">Record 3 minutes</string>
     <string name="btn_signal_stop">Stop recording</string>
     <string name="signal_recorder_running">Recording: %1$d:%2$02d of 3:00, %3$d captures, %4$d change events heard. Keys reported, then assistance properties heard, then values changed so far, the rarest first:</string>
     <string name="signal_recorder_done">Recording from %1$s: %2$d captures, %3$d change events heard, %4$s. Keys reported, then assistance properties heard, then values changed, the rarest first:</string>
+    <string name="log_outbox_sent">Sent to the server.</string>
+    <string name="log_outbox_waiting">Not on the server yet (%1$d waiting: %2$s); it is sent again every 2 minutes.</string>
     <string name="call_log_empty">No upload attempted yet.</string>
     <string name="update_log_title">Updates, newest first:</string>
     <string name="btn_flush_now">Upload now</string>

app/src/test/java/com/evsuite/abrp/LogOutboxTest.java

@@ -0,0 +1,45 @@
+package com.evsuite.abrp;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.Collections;
+
+public class LogOutboxTest {
+
+    @Test
+    public void whatTheServerSaysDecidesTheFile() {
+        assertEquals(LogOutbox.Outcome.SENT, LogOutbox.outcome(204));
+        assertEquals(LogOutbox.Outcome.SENT, LogOutbox.outcome(200));
+        // Worth another try: no answer, not paired yet, a server without logs yet, busy, broken.
+        for (int status : new int[] {0, 401, 404, 408, 429, 500, 502, 503}) {
+            assertEquals(String.valueOf(status), LogOutbox.Outcome.KEEP, LogOutbox.outcome(status));
+        }
+        // Refused for good: it would never pass.
+        for (int status : new int[] {400, 403, 413, 415}) {
+            assertEquals(String.valueOf(status), LogOutbox.Outcome.DROP, LogOutbox.outcome(status));
+        }
+    }
+
+    @Test
+    public void namesAreTheServersKind() {
+        assertTrue(LogOutbox.validName("signal-recording-20261027-085240.txt"));
+        assertFalse(LogOutbox.validName("signal-recording-20261027-085240.txt.tmp"));
+        assertFalse(LogOutbox.validName("../escape.txt"));
+        assertFalse(LogOutbox.validName("Upper.txt"));
+        assertFalse(LogOutbox.validName(null));
+    }
+
+    @Test
+    public void theOldestGoBeyondTheLimit() {
+        assertEquals(Arrays.asList("signal-recording-20261027-084921.txt"),
+                LogOutbox.surplus(Arrays.asList("signal-recording-20261027-085240.txt",
+                        "signal-recording-20261027-084921.txt", "signal-recording-20261027-090000.txt"), 2));
+        assertEquals(Collections.emptyList(),
+                LogOutbox.surplus(Collections.singletonList("signal-recording-20261027-085240.txt"), 2));
+    }
+}

flake.nix

@@ -161,10 +161,46 @@
               echo "Published $tag ($(basename "$apk") and .sha256) at $forge/$repo/releases/tag/$tag"
             '';
           };
+
+          # Fetches the files the car sent from its Logs tab (signal recordings) from the car
+          # server into logs/ (gitignored), those not there yet. Needs the server's LOGS_TOKEN,
+          # from $LOGS_TOKEN or ~/.config/nilsmg4/logs-token; sent in a header, never printed.
+          fetchLogs = pkgs.writeShellApplication {
+            name = "fetch-logs";
+            runtimeInputs = [ pkgs.curl pkgs.jq pkgs.coreutils pkgs.git ];
+            text = ''
+              server=''${SERVER_URL:-https://car.k8s.stinnesbeck.com}
+              token=''${LOGS_TOKEN:-}
+              if [ -z "$token" ] && [ -f "$HOME/.config/nilsmg4/logs-token" ]; then
+                token=$(tr -d '[:space:]' < "$HOME/.config/nilsmg4/logs-token")
+              fi
+              if [ -z "$token" ]; then
+                echo "fetch-logs: no token. Put the server's LOGS_TOKEN in ~/.config/nilsmg4/logs-token (or \$LOGS_TOKEN)." >&2
+                exit 1
+              fi
+              root=$(git rev-parse --show-toplevel)
+              mkdir -p "$root/logs"
+              auth=(-H "Authorization: Bearer $token")
+              fetched=0
+              while IFS= read -r name; do
+                # The server only stores such names; anything else is not a path to write to.
+                if ! [[ "$name" =~ ^[a-z0-9][a-z0-9-]{0,79}\.txt$ ]]; then
+                  echo "fetch-logs: skipping an unexpected name" >&2
+                  continue
+                fi
+                [ -f "$root/logs/$name" ] && continue
+                curl -sSf "''${auth[@]}" -o "$root/logs/$name.part" "$server/v1/logs/$name"
+                mv "$root/logs/$name.part" "$root/logs/$name"
+                echo "logs/$name"
+                fetched=$((fetched + 1))
+              done < <(curl -sSf "''${auth[@]}" "$server/v1/logs" | jq -r '.logs[].name')
+              echo "fetch-logs: $fetched new"
+            '';
+          };
         in
         {
           default = pkgs.mkShell {
-            packages = [ jdk android.androidsdk buildCar publishCar pkgs.go pkgs.gopls pkgs.govulncheck pkgs.influxdb2-server pkgs.influxdb2-cli ];
+            packages = [ jdk android.androidsdk buildCar publishCar fetchLogs pkgs.go pkgs.gopls pkgs.govulncheck pkgs.influxdb2-server pkgs.influxdb2-cli ];
 
             ANDROID_HOME = sdk;
             ANDROID_SDK_ROOT = sdk;
@@ -179,6 +215,7 @@
               echo "  ./gradlew assembleUnstableDebug   # build that can update itself (OTA)"
               echo "  build-car                         # unstable build signed for the car"
               echo "  publish-car                       # publish it for the in-app updater"
+              echo "  fetch-logs                        # the car's recordings from the server, into logs/"
             '';
           };
         });

k8s/README.md

@@ -7,7 +7,7 @@ is applied automatically. Apply them yourself.
 |---|---|
 | `namespace.yaml` | Namespace `mg4` |
 | `influxdb.yaml` | InfluxDB 2.7.12 StatefulSet (10Gi PVC, default storage class), cluster-internal Service, NetworkPolicy admitting only the server and Grafana |
-| `server.yaml` | Go server Deployment (1 replica, non-root, read-only root filesystem) and Service |
+| `server.yaml` | Go server Deployment (1 replica, non-root, read-only root filesystem), Service, and two 1Gi PVCs: the map tile cache and the logs the car sends |
 | `grafana.yaml` | Grafana 13.2.3 Deployment (1Gi PVC), Service; datasource and dashboards provisioned |
 | `grafana/` | The provisioned InfluxDB datasource and the MG4 dashboards (Live, Consumption, Charging) |
 | `ingress.yaml` | Traefik `IngressRoute`s for car.k8s.stinnesbeck.com and Grafana, TLS from Traefik's default certificate |
@@ -22,7 +22,8 @@ is applied automatically. Apply them yourself.
    covered by Traefik's default certificate.
 2. **Create the Secrets.** `cp k8s/secrets/secrets.example.yaml k8s/secrets/secrets.yaml` (gitignored), replace
    every `CHANGE-ME` there (`openssl rand -hex 32`): `influxdb-auth`, `mg4-server` (ingest token,
-   approval password for pairing, the forge token for app updates) and `grafana-admin`.
+   approval password for pairing, the forge token for app updates, the token that reads the
+   car's logs) and `grafana-admin`.
    Keep the template itself on placeholders only.
 3. **Registry access.** The `mg4-server` package on git.stinnesbeck.com is public, so no pull
    secret is needed. If you make it private, add an `imagePullSecrets` entry to `server.yaml`.
@@ -54,6 +55,14 @@ the forge that can only **read** the `nils/mg4` repository, put it there, apply
 restart the server. Without it, updates are off (the car's updater gets a 404). `FORGE_URL`
 and `FORGE_REPO` are set in `server.yaml`.
 
+## Logs from the car
+
+The car sends its signal recordings to the server (`server/README.md`, "Logs from the car"),
+which keeps them on the `mg4-server-logs` volume at `LOGS_DIR`. Reading them needs `LOGS_TOKEN`
+from the `mg4-server` Secret: `openssl rand -hex 32`, put it there (it must differ from
+`INGEST_TOKEN`), apply the Secret and restart the server. For `fetch-logs` on your machine, put
+the same value in `~/.config/nilsmg4/logs-token`. Without it the car still sends; nobody can read.
+
 ## Agent access
 
 [`agent-access/`](agent-access/README.md) creates a service account limited to the `mg4`

k8s/secrets/secrets.example.yaml

@@ -30,6 +30,9 @@ stringData:
   # relays the releases to the car; k8s/README.md, "App updates"). Leave it empty to switch
   # updates off.
   FORGE_TOKEN: CHANGE-ME-read-only-forge-token
+  # Reads the files the car sends from its Logs tab (GET /v1/logs). At least 24 characters and
+  # not the INGEST_TOKEN. Leave it empty to switch reading off; the car can still send.
+  LOGS_TOKEN: CHANGE-ME-openssl-rand-hex-32
 ---
 apiVersion: v1
 kind: Secret

k8s/server.yaml

@@ -16,6 +16,22 @@ spec:
     requests:
       storage: 1Gi
 ---
+# The files the car sends from its Logs tab (signal recordings), read with LOGS_TOKEN. Unlike
+# the map cache these are not fetched again, so they get a volume of their own.
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: mg4-server-logs
+  namespace: mg4
+  labels:
+    app.kubernetes.io/name: mg4-server
+    app.kubernetes.io/part-of: mg4
+spec:
+  accessModes: ["ReadWriteOnce"]
+  resources:
+    requests:
+      storage: 1Gi
+---
 apiVersion: apps/v1
 kind: Deployment
 metadata:
@@ -73,12 +89,16 @@ spec:
               value: https://tiles.openfreemap.org/planet
             - name: MAP_CACHE_DIR
               value: /var/cache/mg4-maps
+            # Files from the car's Logs tab, kept on the volume below (the newest 200, at most
+            # 180 days). Reading them needs LOGS_TOKEN from the Secret; empty switches reading off.
+            - name: LOGS_DIR
+              value: /var/lib/mg4-logs
             - name: INFLUX_TOKEN
               valueFrom:
                 secretKeyRef:
                   name: influxdb-auth
                   key: admin-token
-          # INGEST_TOKEN, APPROVAL_PASSWORD, FORGE_TOKEN.
+          # INGEST_TOKEN, APPROVAL_PASSWORD, FORGE_TOKEN, LOGS_TOKEN.
           envFrom:
             - secretRef:
                 name: mg4-server
@@ -107,10 +127,15 @@ spec:
           volumeMounts:
             - name: maps
               mountPath: /var/cache/mg4-maps
+            - name: logs
+              mountPath: /var/lib/mg4-logs
       volumes:
         - name: maps
           persistentVolumeClaim:
             claimName: mg4-server-maps
+        - name: logs
+          persistentVolumeClaim:
+            claimName: mg4-server-logs
 ---
 apiVersion: v1
 kind: Service

server/README.md

@@ -25,6 +25,8 @@ Environment only; the server refuses to start when a required value is missing.
 | `FORGE_URL`, `FORGE_REPO`, `FORGE_TOKEN` | optional; app updates (below). The token only needs to read the repository |
 | `MAP_TILES_URL` | a TileJSON naming the vector tiles the map's roads come from; default OpenFreeMap's `https://tiles.openfreemap.org/planet`, `off` switches maps off, otherwise https only |
 | `MAP_CACHE_DIR` | where fetched map tiles are kept across restarts (the manifest mounts a volume there); empty keeps them in memory only |
+| `LOGS_DIR` | where the files the car sends from its Logs tab are kept (the manifest mounts a volume there); empty switches logs off |
+| `LOGS_TOKEN` | optional, at least 24 characters and not the `INGEST_TOKEN`; reads those files (below). Empty: the car can send, nobody can read |
 | `LISTEN_ADDR` | default `:8080` |
 
 ## Endpoints
@@ -43,6 +45,7 @@ with (403 otherwise); the shared token works for any.
 - `PUT /v1/charging-sessions/{sessionId}` — a finished charging session (AC or DC, as far as the car was awake) with its curve.
 - `GET /v1/consumption/history/{installationId}` — the car reads its own totals back.
 - `GET /v1/health` — `{"status":"ok"}`.
+- `PUT /v1/logs/{name}` — a file from the car's Logs tab (below).
 
 A malformed request is a 400 naming the field; a database failure is a 500 without detail.
 
@@ -79,6 +82,26 @@ and is kept, and the car hears 503 with `Retry-After: 10` and gets the tile on i
 404 when maps are off. The log says `map tile fetched` with the size, never the tile.
 Map data © OpenStreetMap contributors (ODbL), tiles © OpenMapTiles, served by OpenFreeMap.
 
+## Logs from the car
+
+So a signal recording reaches the owner without a USB stick. The car sends each one when it ends
+(again later when it is offline) with its own token: `PUT /v1/logs/{name}`, plain UTF-8 text,
+gzipped (`Content-Encoding: gzip`) or not; at most 2 MB as sent and 8 MB unpacked. The name is
+the app's (`signal-recording-20261027-085240.txt`: lower-case letters, digits and dashes,
+`.txt`); the same name again replaces the file, so a retry is harmless. 204 when stored. The
+newest 200 files are kept, none older than 180 days.
+
+Reading takes `LOGS_TOKEN`, which can do nothing else, and the car's token cannot read:
+
+```sh
+curl -H "Authorization: Bearer $LOGS_TOKEN" https://car.k8s.stinnesbeck.com/v1/logs          # {logs: [{name, bytes, received}]}, newest first
+curl -H "Authorization: Bearer $LOGS_TOKEN" https://car.k8s.stinnesbeck.com/v1/logs/<name>   # the text
+```
+
+`fetch-logs` in the dev shell fetches the new ones into `logs/` (token from
+`~/.config/nilsmg4/logs-token`). 404 when reading is off. The log says `log received` with the
+name and size, never the contents.
+
 ## Settings from a phone
 
 The ABRP credentials are long to type on the car. With pairing on, the car (with its own token)

server/api.go

@@ -21,6 +21,7 @@ import (
 //	     /v1/settings/…, /settings                settings typed on a phone (handoff_http.go)
 //	GET  /v1/app/…                               app updates from the forge (releases.go)
 //	POST /v1/map/roads                           the roads of one map tile (maps.go)
+//	     /v1/logs/…                              files from the Logs tab, read with LOGS_TOKEN (logs.go)
 //
 // A car authenticates with the shared INGEST_TOKEN or with its own token from pairing
 // (pairing_http.go).
@@ -34,6 +35,8 @@ type API struct {
 	Releases *Releases
 	// Maps serves the roads for the Overview's map from OpenStreetMap vector tiles (maps.go); nil is off.
 	Maps *Maps
+	// Logs keeps the files the car sends from its Logs tab (logs.go); nil is off.
+	Logs *Logs
 	// PublicURL is the server's address as a phone reaches it, for the pairing QR code;
 	// derived from the request when empty.
 	PublicURL string
@@ -54,6 +57,7 @@ func (a *API) Routes() http.Handler {
 	a.handoffRoutes(mux)
 	a.releaseRoutes(mux)
 	a.mapRoutes(mux)
+	a.logRoutes(mux)
 	return mux
 }
 

server/logs.go

@@ -0,0 +1,248 @@
+package main
+
+import (
+	"bytes"
+	"compress/gzip"
+	"crypto/subtle"
+	"errors"
+	"io"
+	"log/slog"
+	"net/http"
+	"os"
+	"path/filepath"
+	"regexp"
+	"sort"
+	"strings"
+	"sync"
+	"time"
+	"unicode/utf8"
+)
+
+// Logs keeps the text files the car sends from its Logs tab (signal recordings) on a volume,
+// so they reach the owner without a USB stick. The car sends with its ingest token; reading
+// needs LOGS_TOKEN, a token of its own, so neither the car's token can read them nor this one
+// write anything.
+//
+//	PUT /v1/logs/{name}   one file from the car (ingest token); the same name again replaces it
+//	GET /v1/logs          the files, newest first (LOGS_TOKEN)
+//	GET /v1/logs/{name}   one file (LOGS_TOKEN)
+//
+// The newest maxLogFiles files younger than maxLogAge are kept. A file's contents never go to
+// the server log, only its name and size.
+type Logs struct {
+	Dir string
+	// ReadToken is LOGS_TOKEN; empty switches reading off (the car can still send).
+	ReadToken string
+
+	mu  sync.Mutex
+	now func() time.Time
+}
+
+const (
+	maxLogWireBytes = 2 << 20 // as sent, gzip or not
+	maxLogBytes     = 8 << 20 // as stored
+	maxLogFiles     = 200
+	maxLogAge       = 180 * 24 * time.Hour
+)
+
+// logName is what a file may be called: the app's own names, e.g. signal-recording-20261027-085240.txt.
+var logName = regexp.MustCompile(`^[a-z0-9][a-z0-9-]{0,79}\.txt$`)
+
+// NewLogs keeps the files in dir, which must exist.
+func NewLogs(dir, readToken string) *Logs {
+	return &Logs{Dir: dir, ReadToken: readToken, now: time.Now}
+}
+
+func (a *API) logRoutes(mux *http.ServeMux) {
+	if a.Logs == nil {
+		return
+	}
+	mux.HandleFunc("PUT /v1/logs/{name}", a.putLog)
+	mux.HandleFunc("GET /v1/logs", a.Logs.list)
+	mux.HandleFunc("GET /v1/logs/{name}", a.Logs.get)
+}
+
+func (a *API) putLog(w http.ResponseWriter, r *http.Request) {
+	if _, ok := a.authenticate(r); !ok {
+		writeJSON(w, http.StatusUnauthorized, map[string]string{"error": "unauthorized"})
+		return
+	}
+	name := r.PathValue("name")
+	if !logName.MatchString(name) {
+		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "name must be lower-case letters, digits and dashes, ending in .txt"})
+		return
+	}
+	text, status, msg := readLogBody(r)
+	if status != 0 {
+		writeJSON(w, status, map[string]string{"error": msg})
+		return
+	}
+	if err := a.Logs.save(name, text); err != nil {
+		slog.Error("log not stored", "name", name, "error", err)
+		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": "internal server error"})
+		return
+	}
+	slog.Info("log received", "name", name, "bytes", len(text))
+	w.WriteHeader(http.StatusNoContent)
+}
+
+// readLogBody is the request's text, un-gzipped when it says so; a status and message when it
+// is too large, not gzip after all, or not UTF-8 text.
+func readLogBody(r *http.Request) ([]byte, int, string) {
+	wire, err := io.ReadAll(io.LimitReader(r.Body, maxLogWireBytes+1))
+	if err != nil {
+		return nil, http.StatusBadRequest, "body could not be read"
+	}
+	if len(wire) > maxLogWireBytes {
+		return nil, http.StatusRequestEntityTooLarge, "body is too large"
+	}
+	text := wire
+	switch strings.ToLower(r.Header.Get("Content-Encoding")) {
+	case "", "identity":
+	case "gzip":
+		zr, err := gzip.NewReader(bytes.NewReader(wire))
+		if err != nil {
+			return nil, http.StatusBadRequest, "body is not gzip"
+		}
+		text, err = io.ReadAll(io.LimitReader(zr, maxLogBytes+1))
+		if err != nil {
+			return nil, http.StatusBadRequest, "body is not gzip"
+		}
+	default:
+		return nil, http.StatusUnsupportedMediaType, "only gzip or no encoding"
+	}
+	if len(text) > maxLogBytes {
+		return nil, http.StatusRequestEntityTooLarge, "body is too large"
+	}
+	if !utf8.Valid(text) {
+		return nil, http.StatusBadRequest, "body is not UTF-8 text"
+	}
+	return text, 0, ""
+}
+
+// save writes the file whole (a temporary file renamed into place), then prunes.
+func (l *Logs) save(name string, text []byte) error {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	tmp, err := os.CreateTemp(l.Dir, ".incoming-*")
+	if err != nil {
+		return err
+	}
+	defer os.Remove(tmp.Name()) // gone after the rename; cleans up after a failure
+	if _, err := tmp.Write(text); err != nil {
+		tmp.Close()
+		return err
+	}
+	if err := tmp.Close(); err != nil {
+		return err
+	}
+	if err := os.Rename(tmp.Name(), filepath.Join(l.Dir, name)); err != nil {
+		return err
+	}
+	l.prune()
+	return nil
+}
+
+type logEntry struct {
+	Name     string    `json:"name"`
+	Bytes    int64     `json:"bytes"`
+	Received time.Time `json:"received"`
+}
+
+// entries are the stored files, newest first.
+func (l *Logs) entries() ([]logEntry, error) {
+	dir, err := os.ReadDir(l.Dir)
+	if err != nil {
+		return nil, err
+	}
+	var out []logEntry
+	for _, e := range dir {
+		if !e.Type().IsRegular() || !logName.MatchString(e.Name()) {
+			continue
+		}
+		info, err := e.Info()
+		if err != nil {
+			continue
+		}
+		out = append(out, logEntry{Name: e.Name(), Bytes: info.Size(), Received: info.ModTime().UTC()})
+	}
+	sort.Slice(out, func(i, j int) bool {
+		if !out[i].Received.Equal(out[j].Received) {
+			return out[i].Received.After(out[j].Received)
+		}
+		return out[i].Name > out[j].Name
+	})
+	return out, nil
+}
+
+// prune removes all but the newest maxLogFiles and anything older than maxLogAge.
+func (l *Logs) prune() {
+	entries, err := l.entries()
+	if err != nil {
+		return
+	}
+	cutoff := l.now().Add(-maxLogAge)
+	for i, e := range entries {
+		if i >= maxLogFiles || e.Received.Before(cutoff) {
+			if err := os.Remove(filepath.Join(l.Dir, e.Name)); err != nil && !errors.Is(err, os.ErrNotExist) {
+				slog.Warn("old log not removed", "name", e.Name, "error", err)
+			}
+		}
+	}
+}
+
+// mayRead accepts LOGS_TOKEN only, compared in constant time; main refuses a short one.
+func (l *Logs) mayRead(w http.ResponseWriter, r *http.Request) bool {
+	if l.ReadToken == "" {
+		writeJSON(w, http.StatusNotFound, map[string]string{"error": "reading logs is off (no LOGS_TOKEN)"})
+		return false
+	}
+	supplied, ok := strings.CutPrefix(r.Header.Get("Authorization"), "Bearer ")
+	if !ok || subtle.ConstantTimeCompare([]byte(supplied), []byte(l.ReadToken)) != 1 {
+		writeJSON(w, http.StatusUnauthorized, map[string]string{"error": "unauthorized"})
+		return false
+	}
+	return true
+}
+
+func (l *Logs) list(w http.ResponseWriter, r *http.Request) {
+	if !l.mayRead(w, r) {
+		return
+	}
+	l.mu.Lock()
+	entries, err := l.entries()
+	l.mu.Unlock()
+	if err != nil {
+		slog.Error("logs not listed", "error", err)
+		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": "internal server error"})
+		return
+	}
+	writeJSON(w, http.StatusOK, map[string]any{"logs": append([]logEntry{}, entries...)})
+}
+
+func (l *Logs) get(w http.ResponseWriter, r *http.Request) {
+	if !l.mayRead(w, r) {
+		return
+	}
+	name := r.PathValue("name")
+	if !logName.MatchString(name) {
+		writeJSON(w, http.StatusNotFound, map[string]string{"error": "no such log"})
+		return
+	}
+	l.mu.Lock()
+	text, err := os.ReadFile(filepath.Join(l.Dir, name))
+	l.mu.Unlock()
+	if errors.Is(err, os.ErrNotExist) {
+		writeJSON(w, http.StatusNotFound, map[string]string{"error": "no such log"})
+		return
+	}
+	if err != nil {
+		slog.Error("log not read", "name", name, "error", err)
+		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": "internal server error"})
+		return
+	}
+	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+	w.Header().Set("X-Content-Type-Options", "nosniff")
+	w.WriteHeader(http.StatusOK)
+	_, _ = w.Write(text)
+}

server/logs_test.go

@@ -0,0 +1,212 @@
+package main
+
+import (
+	"bytes"
+	"compress/gzip"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+)
+
+const testLogsToken = "logs-read-token-0123456789abcdef"
+
+func newLogsAPI(t *testing.T) (*API, string) {
+	t.Helper()
+	api, _ := newTestAPI()
+	dir := t.TempDir()
+	api.Logs = NewLogs(dir, testLogsToken)
+	return api, dir
+}
+
+func gzipped(t *testing.T, text string) []byte {
+	t.Helper()
+	var b bytes.Buffer
+	zw := gzip.NewWriter(&b)
+	if _, err := zw.Write([]byte(text)); err != nil {
+		t.Fatal(err)
+	}
+	if err := zw.Close(); err != nil {
+		t.Fatal(err)
+	}
+	return b.Bytes()
+}
+
+func putLog(t *testing.T, h http.Handler, name, token string, body []byte, encoding string) *httptest.ResponseRecorder {
+	t.Helper()
+	req := httptest.NewRequest("PUT", "/v1/logs/"+name, bytes.NewReader(body))
+	req.Header.Set("Authorization", "Bearer "+token)
+	req.Header.Set("Content-Type", "text/plain; charset=utf-8")
+	if encoding != "" {
+		req.Header.Set("Content-Encoding", encoding)
+	}
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+	return rec
+}
+
+func TestTheCarSendsALogAndTheOwnerReadsIt(t *testing.T) {
+	api, _ := newLogsAPI(t)
+	h := api.Routes()
+	const name = "signal-recording-20261027-085240.txt"
+	text := "Signal recording, 37 captures\nlistening to 108 assistance properties\n"
+
+	if rec := putLog(t, h, name, testToken, gzipped(t, text), "gzip"); rec.Code != http.StatusNoContent {
+		t.Fatalf("put: %d %s", rec.Code, rec.Body)
+	}
+
+	rec := do(t, h, "GET", "/v1/logs", testLogsToken, "")
+	if rec.Code != 200 {
+		t.Fatalf("list: %d %s", rec.Code, rec.Body)
+	}
+	var list struct {
+		Logs []logEntry `json:"logs"`
+	}
+	if err := json.Unmarshal(rec.Body.Bytes(), &list); err != nil || len(list.Logs) != 1 || list.Logs[0].Name != name ||
+		list.Logs[0].Bytes != int64(len(text)) {
+		t.Fatalf("list: %v %s", err, rec.Body)
+	}
+
+	rec = do(t, h, "GET", "/v1/logs/"+name, testLogsToken, "")
+	if rec.Code != 200 || rec.Body.String() != text || !strings.HasPrefix(rec.Header().Get("Content-Type"), "text/plain") {
+		t.Fatalf("get: %d %q", rec.Code, rec.Body)
+	}
+
+	// Sent again (a retry), it replaces itself.
+	if rec := putLog(t, h, name, testToken, []byte("again\n"), ""); rec.Code != http.StatusNoContent {
+		t.Fatalf("put again: %d", rec.Code)
+	}
+	if rec := do(t, h, "GET", "/v1/logs/"+name, testLogsToken, ""); rec.Body.String() != "again\n" {
+		t.Fatalf("replaced: %q", rec.Body)
+	}
+}
+
+func TestLogTokensDoNotCross(t *testing.T) {
+	api, _ := newLogsAPI(t)
+	h := api.Routes()
+	name := "signal-recording-1.txt"
+	if rec := putLog(t, h, name, testLogsToken, []byte("x"), ""); rec.Code != http.StatusUnauthorized {
+		t.Fatalf("the read token wrote: %d", rec.Code)
+	}
+	if rec := putLog(t, h, name, testToken, []byte("x"), ""); rec.Code != http.StatusNoContent {
+		t.Fatalf("put: %d", rec.Code)
+	}
+	for _, path := range []string{"/v1/logs", "/v1/logs/" + name} {
+		for _, token := range []string{"", testToken, testLogsToken + "x"} {
+			if rec := do(t, h, "GET", path, token, ""); rec.Code != http.StatusUnauthorized {
+				t.Fatalf("GET %s with %q: %d", path, token, rec.Code)
+			}
+		}
+	}
+}
+
+func TestReadingIsOffWithoutALogsToken(t *testing.T) {
+	api, _ := newLogsAPI(t)
+	api.Logs.ReadToken = ""
+	h := api.Routes()
+	if rec := putLog(t, h, "a.txt", testToken, []byte("x"), ""); rec.Code != http.StatusNoContent {
+		t.Fatalf("put: %d", rec.Code)
+	}
+	if rec := do(t, h, "GET", "/v1/logs", "", ""); rec.Code != http.StatusNotFound {
+		t.Fatalf("list: %d", rec.Code)
+	}
+}
+
+func TestBadLogsAreRefused(t *testing.T) {
+	api, dir := newLogsAPI(t)
+	h := api.Routes()
+	for _, c := range []struct {
+		name, encoding string
+		body           []byte
+		want           int
+	}{
+		{"..%2Fescape.txt", "", []byte("x"), http.StatusBadRequest},
+		{"Upper.txt", "", []byte("x"), http.StatusBadRequest},
+		{"no-suffix", "", []byte("x"), http.StatusBadRequest},
+		{".hidden.txt", "", []byte("x"), http.StatusBadRequest},
+		{"a.txt", "gzip", []byte("not gzip"), http.StatusBadRequest},
+		{"a.txt", "br", []byte("x"), http.StatusUnsupportedMediaType},
+		{"a.txt", "", []byte{0xff, 0xfe, 0x00}, http.StatusBadRequest},
+		{"a.txt", "", make([]byte, maxLogWireBytes+1), http.StatusRequestEntityTooLarge},
+		{"a.txt", "gzip", gzipped(t, strings.Repeat("a", maxLogBytes+1)), http.StatusRequestEntityTooLarge},
+	} {
+		if rec := putLog(t, h, c.name, testToken, c.body, c.encoding); rec.Code != c.want {
+			t.Errorf("%s %s: %d, want %d (%s)", c.name, c.encoding, rec.Code, c.want, rec.Body)
+		}
+	}
+	if files, _ := os.ReadDir(dir); len(files) != 0 {
+		t.Fatalf("stored: %v", files)
+	}
+	if rec := do(t, h, "GET", "/v1/logs/missing.txt", testLogsToken, ""); rec.Code != http.StatusNotFound {
+		t.Fatalf("missing: %d", rec.Code)
+	}
+}
+
+func TestOldAndSurplusLogsArePruned(t *testing.T) {
+	dir := t.TempDir()
+	l := NewLogs(dir, testLogsToken)
+	// The new file gets the real time as its own, so the others are placed before it.
+	now := time.Now()
+	old := filepath.Join(dir, "old.txt")
+	if err := os.WriteFile(old, []byte("x"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.Chtimes(old, now.Add(-maxLogAge-time.Hour), now.Add(-maxLogAge-time.Hour)); err != nil {
+		t.Fatal(err)
+	}
+	for i := 0; i < maxLogFiles+5; i++ {
+		p := filepath.Join(dir, fmt.Sprintf("f-%03d.txt", i))
+		if err := os.WriteFile(p, []byte("x"), 0o600); err != nil {
+			t.Fatal(err)
+		}
+		at := now.Add(-time.Duration(maxLogFiles+5-i) * time.Minute)
+		if err := os.Chtimes(p, at, at); err != nil {
+			t.Fatal(err)
+		}
+	}
+	if err := l.save("new.txt", []byte("y")); err != nil {
+		t.Fatal(err)
+	}
+	entries, _ := l.entries()
+	if len(entries) != maxLogFiles || entries[0].Name != "new.txt" {
+		t.Fatalf("%d kept, first %s", len(entries), entries[0].Name)
+	}
+	if _, err := os.Stat(old); !os.IsNotExist(err) {
+		t.Fatal("the old one is still there")
+	}
+	if _, err := os.Stat(filepath.Join(dir, "f-000.txt")); !os.IsNotExist(err) {
+		t.Fatal("the oldest surplus one is still there")
+	}
+}
+
+func TestLogsConfig(t *testing.T) {
+	base := map[string]string{"INFLUX_URL": "http://i", "INFLUX_TOKEN": "t", "INFLUX_ORG": "o", "INGEST_TOKEN": testToken}
+	env := func(extra map[string]string) func(string) string {
+		return func(k string) string {
+			if v, ok := extra[k]; ok {
+				return v
+			}
+			return base[k]
+		}
+	}
+	for _, c := range []struct {
+		extra map[string]string
+		ok    bool
+	}{
+		{map[string]string{}, true},
+		{map[string]string{"LOGS_DIR": "/l"}, true},
+		{map[string]string{"LOGS_DIR": "/l", "LOGS_TOKEN": testLogsToken}, true},
+		{map[string]string{"LOGS_TOKEN": testLogsToken}, false},
+		{map[string]string{"LOGS_DIR": "/l", "LOGS_TOKEN": "short"}, false},
+		{map[string]string{"LOGS_DIR": "/l", "LOGS_TOKEN": testToken}, false},
+	} {
+		if _, err := loadConfig(env(c.extra)); (err == nil) != c.ok {
+			t.Errorf("%v: %v", c.extra, err)
+		}
+	}
+}

server/main.go

@@ -36,6 +36,8 @@ type config struct {
 	forgeToken   string
 	mapTilesURL  string
 	mapCacheDir  string
+	logsDir      string
+	logsToken    string
 }
 
 // loadConfig reads the environment and fails closed: a missing InfluxDB setting or a
@@ -55,6 +57,8 @@ func loadConfig(getenv func(string) string) (config, error) {
 		forgeToken:   getenv("FORGE_TOKEN"),
 		mapTilesURL:  getenv("MAP_TILES_URL"),
 		mapCacheDir:  getenv("MAP_CACHE_DIR"),
+		logsDir:      getenv("LOGS_DIR"),
+		logsToken:    getenv("LOGS_TOKEN"),
 	}
 	if c.listenAddr == "" {
 		c.listenAddr = ":8080"
@@ -89,6 +93,17 @@ func loadConfig(getenv func(string) string) (config, error) {
 			return config{}, errors.New("MAP_TILES_URL must be an https URL or \"off\"")
 		}
 	}
+	// Logs from the car are optional (LOGS_DIR); reading them needs a token of their own, as
+	// long as the ingest token, and never the ingest token itself.
+	if c.logsToken != "" && c.logsDir == "" {
+		return config{}, errors.New("LOGS_TOKEN is set but LOGS_DIR is not")
+	}
+	if c.logsToken != "" && len(c.logsToken) < minIngestTokenLength {
+		return config{}, fmt.Errorf("LOGS_TOKEN must be at least %d characters", minIngestTokenLength)
+	}
+	if c.logsToken != "" && c.logsToken == c.ingestToken {
+		return config{}, errors.New("LOGS_TOKEN must differ from INGEST_TOKEN")
+	}
 	if c.approvalPass != "" && len(c.approvalPass) < minApprovalPasswordLength {
 		return config{}, fmt.Errorf("APPROVAL_PASSWORD must be at least %d characters", minApprovalPasswordLength)
 	}
@@ -127,6 +142,13 @@ func main() {
 		}
 		api.Maps = NewMaps(cfg.mapTilesURL, cfg.mapCacheDir, mapUserAgent)
 	}
+	if cfg.logsDir != "" {
+		if err := os.MkdirAll(cfg.logsDir, 0o700); err != nil {
+			slog.Error("logs directory not usable", "error", err)
+			os.Exit(1)
+		}
+		api.Logs = NewLogs(cfg.logsDir, cfg.logsToken)
+	}
 
 	srv := &http.Server{
 		Addr:              cfg.listenAddr,
@@ -142,7 +164,7 @@ func main() {
 	go func() {
 		slog.Info("listening", "addr", cfg.listenAddr, "bucket", cfg.influxBucket,
 			"pairing", pairing.Enabled(), "pairedDevices", len(devices), "appUpdates", releases.enabled(),
-			"maps", api.Maps != nil)
+			"maps", api.Maps != nil, "logs", api.Logs != nil, "logsReadable", api.Logs != nil && cfg.logsToken != "")
 		if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
 			slog.Error("server failed", "error", err)
 			os.Exit(1)