From f8cad55e9c3f3df782083dcd0c9747ad2f3b9052 Mon Sep 17 00:00:00 2001
From: Konrad Neitzel <konrad@neitzel.de>
Date: Wed, 7 Oct 2026 12:14:41 +0200
Subject: [PATCH] Switch the lab reflector to jayReflector and harden local
 station use.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Build DJ1JAY’s fork with an optional Satellite/Trunk stub, allow -c/--config, open capture and playback as separate devices, and add a lab start helper.

Co-authored-by: Cursor <cursoragent@cursor.com>
---
 .gitignore                                   |   2 +-
 app.go                                       |  17 +-
 audio/device.go                              | 114 ++++++----
 config_path.go                               |  42 ++++
 config_path_test.go                          | 124 +++++++++++
 docs/adr/0002-home-directory-config.md       |   2 +-
 docs/code-review.md                          | 218 +++++++++++++++++++
 docs/svxlink.md                              |  86 ++++++--
 main.go                                      |   2 +-
 station/behavior_test.go                     |  10 +-
 station/config.go                            |  10 +-
 station/config_test.go                       |  55 +++--
 station/lab_reflector_test.go                |   2 +-
 station/log_test.go                          |   4 +-
 station/session_test.go                      |   2 +-
 station/software.go                          |   4 +-
 svxlink-docker/.env.example                  |   9 +-
 svxlink-docker/.gitignore                    |   4 +
 svxlink-docker/Dockerfile                    |  85 ++++----
 svxlink-docker/config/svxreflector.conf      |  15 +-
 svxlink-docker/config/svxreflector.link.conf |  41 ++++
 svxlink-docker/docker-compose.yml            |  28 ++-
 svxlink-docker/entrypoint.sh                 |  72 +++---
 teststart.sh                                 | 124 +++++++++++
 24 files changed, 847 insertions(+), 225 deletions(-)
 create mode 100644 config_path.go
 create mode 100644 config_path_test.go
 create mode 100644 docs/code-review.md
 create mode 100644 svxlink-docker/config/svxreflector.link.conf
 create mode 100755 teststart.sh

diff --git a/.gitignore b/.gitignore
index 5e1078d..c5c34f2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,2 @@
 build/bin/
-frontend/wailsjs/
+frontend/wailsjs/
\ No newline at end of file
diff --git a/app.go b/app.go
index 036413f..483ffbc 100644
--- a/app.go
+++ b/app.go
@@ -2,9 +2,6 @@ package main
 
 import (
 	"context"
-	"fmt"
-	"os"
-	"path/filepath"
 
 	"gitea.neitzel.de/konrad/funknetz/audio"
 	"gitea.neitzel.de/konrad/funknetz/station"
@@ -47,18 +44,10 @@ func (a *App) HoldSpace() { a.station.HoldSpace() }
 // ReleaseSpace reports that Space was released.
 func (a *App) ReleaseSpace() { a.station.ReleaseSpace() }
 
-func configPath() (string, error) {
-	home, err := os.UserHomeDir()
+func openStation(args []string) (*station.Station, error) {
+	path, err := resolveConfigPath(args)
 	if err != nil {
-		return "", err
-	}
-	return filepath.Join(home, ".funknetz.json"), nil
-}
-
-func openStation() (*station.Station, error) {
-	path, err := configPath()
-	if err != nil {
-		return nil, fmt.Errorf("could not be read")
+		return nil, err
 	}
 	return station.New(station.Options{ConfigPath: path})
 }
diff --git a/audio/device.go b/audio/device.go
index 0345812..2a21d38 100644
--- a/audio/device.go
+++ b/audio/device.go
@@ -12,47 +12,51 @@ import (
 
 const stationRate = 16000
 
-// Start opens the default input and output and converts them to and from
-// 16 kHz mono. It returns when the devices are running. They close when ctx ends.
+// Start opens the default capture device and the default playback device and
+// converts them to and from 16 kHz mono. It returns when both devices are
+// running. They close when ctx ends.
 func Start(ctx context.Context, capture func([]int16), playback func() []int16) error {
 	mctx, err := malgo.InitContext(nil, malgo.ContextConfig{}, nil)
 	if err != nil {
 		return err
 	}
-	cfg := malgo.DefaultDeviceConfig(malgo.Duplex)
-	cfg.SampleRate = stationRate
-	cfg.Capture.Format = malgo.FormatS16
-	cfg.Capture.Channels = 1
-	cfg.Playback.Format = malgo.FormatS16
-	cfg.Playback.Channels = 1
 
-	var playRes, capRes converter
+	capCfg := malgo.DefaultDeviceConfig(malgo.Capture)
+	capCfg.SampleRate = stationRate
+	capCfg.Capture.Format = malgo.FormatS16
+	capCfg.Capture.Channels = 1
+
+	playCfg := malgo.DefaultDeviceConfig(malgo.Playback)
+	playCfg.SampleRate = stationRate
+	playCfg.Playback.Format = malgo.FormatS16
+	playCfg.Playback.Channels = 1
+
+	var capRes, playRes converter
 	var playBuf []int16
-	callbacks := malgo.DeviceCallbacks{
-		Data: func(output, input []byte, framecount uint32) {
-			if len(input) > 0 {
-				channels := 1
-				if framecount > 0 {
-					channels = len(input) / int(framecount) / 2
-				}
-				if channels < 1 {
-					channels = 1
-				}
-				pcm := capRes.Convert(downmix(bytesToS16(input), channels))
-				if len(pcm) > 0 {
-					capture(pcm)
-				}
+
+	capDev, err := malgo.InitDevice(mctx.Context, capCfg, malgo.DeviceCallbacks{
+		Data: func(_, input []byte, framecount uint32) {
+			if len(input) == 0 {
+				return
 			}
+			channels := channelCount(len(input), framecount)
+			pcm := capRes.Convert(downmix(bytesToS16(input), channels))
+			if len(pcm) > 0 {
+				capture(pcm)
+			}
+		},
+	})
+	if err != nil {
+		mctx.Free()
+		return err
+	}
+
+	playDev, err := malgo.InitDevice(mctx.Context, playCfg, malgo.DeviceCallbacks{
+		Data: func(output, _ []byte, framecount uint32) {
 			if len(output) == 0 {
 				return
 			}
-			channels := 1
-			if framecount > 0 {
-				channels = len(output) / int(framecount) / 2
-			}
-			if channels < 1 {
-				channels = 1
-			}
+			channels := channelCount(len(output), framecount)
 			playBuf = append(playBuf, playRes.Convert(playback())...)
 			need := int(framecount)
 			var frame []int16
@@ -66,32 +70,60 @@ func Start(ctx context.Context, capture func([]int16), playback func() []int16)
 			}
 			writeS16(output, frame, channels)
 		},
-	}
-	dev, err := malgo.InitDevice(mctx.Context, cfg, callbacks)
+	})
 	if err != nil {
+		capDev.Uninit()
 		mctx.Free()
 		return err
 	}
-	rate := int(dev.SampleRate())
-	if rate == 0 {
-		rate = stationRate
+
+	capRate := int(capDev.SampleRate())
+	if capRate == 0 {
+		capRate = stationRate
 	}
-	capRes = converter{from: rate, to: stationRate}
-	playRes = converter{from: stationRate, to: rate}
-	if err := dev.Start(); err != nil {
-		dev.Uninit()
+	playRate := int(playDev.SampleRate())
+	if playRate == 0 {
+		playRate = stationRate
+	}
+	capRes = converter{from: capRate, to: stationRate}
+	playRes = converter{from: stationRate, to: playRate}
+
+	if err := capDev.Start(); err != nil {
+		playDev.Uninit()
+		capDev.Uninit()
 		mctx.Free()
 		return err
 	}
+	if err := playDev.Start(); err != nil {
+		capDev.Stop()
+		playDev.Uninit()
+		capDev.Uninit()
+		mctx.Free()
+		return err
+	}
+
 	go func() {
 		<-ctx.Done()
-		dev.Stop()
-		dev.Uninit()
+		_ = playDev.Stop()
+		_ = capDev.Stop()
+		playDev.Uninit()
+		capDev.Uninit()
 		mctx.Free()
 	}()
 	return nil
 }
 
+func channelCount(bytes int, framecount uint32) int {
+	channels := 1
+	if framecount > 0 {
+		channels = bytes / int(framecount) / 2
+	}
+	if channels < 1 {
+		return 1
+	}
+	return channels
+}
+
 func bytesToS16(b []byte) []int16 {
 	n := len(b) / 2
 	out := make([]int16, n)
diff --git a/config_path.go b/config_path.go
new file mode 100644
index 0000000..424bdd3
--- /dev/null
+++ b/config_path.go
@@ -0,0 +1,42 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+)
+
+func defaultConfigPath() (string, error) {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return "", err
+	}
+	return filepath.Join(home, ".funknetz.json"), nil
+}
+
+// resolveConfigPath picks the config file from -c / --config in args (no program name).
+// The default is ~/.funknetz.json. A relative path is resolved against the process CWD.
+func resolveConfigPath(args []string) (string, error) {
+	fs := flag.NewFlagSet("funknetz", flag.ContinueOnError)
+	fs.SetOutput(io.Discard)
+	var config string
+	fs.StringVar(&config, "config", "", "path to the station config file")
+	fs.StringVar(&config, "c", "", "path to the station config file")
+	if err := fs.Parse(args); err != nil {
+		return "", err
+	}
+	if config == "" {
+		path, err := defaultConfigPath()
+		if err != nil {
+			return "", fmt.Errorf("config path: %w", err)
+		}
+		return path, nil
+	}
+	abs, err := filepath.Abs(config)
+	if err != nil {
+		return "", fmt.Errorf("config path: %w", err)
+	}
+	return abs, nil
+}
diff --git a/config_path_test.go b/config_path_test.go
new file mode 100644
index 0000000..8555dbf
--- /dev/null
+++ b/config_path_test.go
@@ -0,0 +1,124 @@
+//go:build !bindings
+
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+)
+
+func TestResolveConfigPathDefaultIsHome(t *testing.T) {
+	got, err := resolveConfigPath(nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	home, err := os.UserHomeDir()
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := filepath.Join(home, ".funknetz.json")
+	if got != want {
+		t.Fatalf("resolveConfigPath(nil) = %q, want %q", got, want)
+	}
+}
+
+func TestResolveConfigPathLongAndShort(t *testing.T) {
+	dir := t.TempDir()
+	abs := filepath.Join(dir, "lab.json")
+
+	got, err := resolveConfigPath([]string{"--config", abs})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got != abs {
+		t.Fatalf("--config = %q, want %q", got, abs)
+	}
+
+	got, err = resolveConfigPath([]string{"-c", abs})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got != abs {
+		t.Fatalf("-c = %q, want %q", got, abs)
+	}
+}
+
+func TestResolveConfigPathRelativeBecomesAbsolute(t *testing.T) {
+	dir := t.TempDir()
+	cwd, err := os.Getwd()
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() { _ = os.Chdir(cwd) })
+	if err := os.Chdir(dir); err != nil {
+		t.Fatal(err)
+	}
+
+	got, err := resolveConfigPath([]string{"-c", "./funknetz.json"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	want, err := filepath.EvalSymlinks(filepath.Join(dir, "funknetz.json"))
+	if err != nil {
+		// File need not exist; resolve the directory and join.
+		base, err := filepath.EvalSymlinks(dir)
+		if err != nil {
+			t.Fatal(err)
+		}
+		want = filepath.Join(base, "funknetz.json")
+	}
+	gotEval, err := filepath.EvalSymlinks(filepath.Dir(got))
+	if err != nil {
+		t.Fatal(err)
+	}
+	got = filepath.Join(gotEval, filepath.Base(got))
+	if got != want {
+		t.Fatalf("relative -c = %q, want %q", got, want)
+	}
+}
+
+func TestOpenStationUsesResolvedPath(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "custom.json")
+
+	_, err := openStation([]string{"-c", path})
+	if err == nil {
+		t.Fatal("openStation() error = nil, want rejection after creating the file")
+	}
+	if !strings.Contains(err.Error(), "created") {
+		t.Fatalf("openStation() error = %q, want it to say the file was created", err.Error())
+	}
+
+	info, err := os.Stat(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got, want := info.Mode().Perm(), os.FileMode(0o600); got != want {
+		t.Fatalf("mode = %o, want %o", got, want)
+	}
+
+	// Same rules as the home file: a second open with a filled config works.
+	body := `{
+  "host": "127.0.0.1",
+  "port": 5300,
+  "callsign": "DL0FN-1",
+  "authKey": "local-lab-secret-change-me",
+  "talkGroup": 9,
+  "enableLogging": false,
+  "logFile": "` + filepath.Join(dir, "funknetz.log") + `"
+}
+`
+	if err := os.WriteFile(path, []byte(body), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	st, err := openStation([]string{"--config", path})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if st.State().Callsign != "DL0FN-1" {
+		t.Fatalf("callsign = %q, want DL0FN-1", st.State().Callsign)
+	}
+}
diff --git a/docs/adr/0002-home-directory-config.md b/docs/adr/0002-home-directory-config.md
index 64acd8c..c896c48 100644
--- a/docs/adr/0002-home-directory-config.md
+++ b/docs/adr/0002-home-directory-config.md
@@ -1,3 +1,3 @@
 # Hand-edited config in the home directory
 
-The operator edits connection settings by hand. There is no settings window in version 1. The file is `~/.funknetz.json`, created mode 0600 when missing. Application Support would match other Mac apps and would be a worse place to open in an editor. That path is part of the station's contract; moving it later strands existing files.
+The operator edits connection settings by hand. There is no settings window in version 1. The default file is `~/.funknetz.json`, created mode 0600 when missing. Application Support would match other Mac apps and would be a worse place to open in an editor. That default path is part of the station's contract; moving it later strands existing files. `-c` / `--config` may select another file; create, rewrite, and validate rules are the same—only the path changes.
diff --git a/docs/code-review.md b/docs/code-review.md
new file mode 100644
index 0000000..4fe8f01
--- /dev/null
+++ b/docs/code-review.md
@@ -0,0 +1,218 @@
+# Code review: funknetz
+
+**Date:** 2026-10-07  
+**Scope:** Full review of the funknetz checkout (headset station + local SvxReflector lab).  
+**Fixed point:** `8e75515` (`Record the station glossary and the window and config decisions.`)  
+**Compared tip:** `HEAD` = `f90b615`  
+**Diff:** `git diff 8e75515...HEAD` (4222 insertions across 38 files)  
+**Spec:** [docs/issues/2026-10-03-funknetz-station/spec.md](../../docs/issues/2026-10-03-funknetz-station/spec.md) (workspace issue tracker)  
+**Standards:** [knowledge/engineering/go/](../../knowledge/engineering/go/), [CONTEXT.md](../CONTEXT.md), [docs/adr/](./adr/)
+
+Two axes below are independent. Findings are not merged or ranked across axes.
+
+### Commits in range (`8e75515..HEAD`)
+
+| Commit | Summary |
+| --- | --- |
+| `9c4f662` | Join one FM-Funknetz talk group from a headset window |
+| `6233292` | Pause playback while transmitting and declare microphone use |
+| `ec5f660` | Append an optional station log and announce the software after login |
+| `eda79e6` | Add a local SvxReflector Docker lab for headset testing |
+| `f90b615` | Merge branch `lab/svxlink-docker` |
+
+### Working tree (not in `HEAD` diff)
+
+At review time, uncommitted edits touched `docs/svxlink.md`, `svxlink-docker/` (Dockerfile, compose, entrypoint, conf, `.env.example`, `.gitignore`), root `.gitignore`, and an untracked `svxlink-docker/config/svxreflector.link.conf`. Protocol and lab notes in this report include that working tree where it clarifies jayReflector Satellite/Trunk; Standards and Spec axes stay on `8e75515...HEAD` only.
+
+### Tests run
+
+```sh
+GOWORK=off go test ./station/ -count=1   # ok (~10s)
+```
+
+`main`, `audio`, and `internal/opus` have no package tests. `TestConnectsToLabReflector` skips when `127.0.0.1:5300` is down (or `FUNKNETZ_LAB=0`).
+
+---
+
+## Standards
+
+### Documented standards
+
+**Hard — `modern.md` (new JSON → `encoding/json/v2`)**  
+`station/software.go` marshals with v1 `encoding/json` while `station/config.go` already uses `encoding/json/v2`. Same module, new code: prefer v2.
+
+**Hard — `errors.md` (wrap with `%w`; don’t drop causes)**  
+Underlying failures are replaced with a bare string:
+- `app.go` / config path resolution paths that surface `could not be read`
+- `station/config.go` `loadConfig` / `parseConfig` / rewrite path: same `"could not be read"` without `%w`
+
+**Hard — `testing.md` (prefer `t.Fatal` over `panic`)**  
+`station/config_test.go` `configJSON` / `configWithLog`: `panic(err)` on marshal failure.
+
+**Judgement — `errors.md` / `modern.md` (`errors.Is`)**  
+`station/config.go`: `os.IsNotExist(err)` — prefer `errors.Is(err, fs.ErrNotExist)`.
+
+**Judgement — `concurrency-context.md` + `functions-methods.md` (synchronous APIs; obvious goroutine lifetime)**  
+`audio.Start` returns after starting a cleanup goroutine on `ctx.Done()`. `app.go` fire-and-forgets `Run` with `_ =` (comment present; discard rule satisfied).
+
+**Judgement — `modern.md` (`slices.Contains`)**  
+`station/protocol.go` `hasOPUS` hand-loops instead of `slices.Contains`.
+
+**OK / tooling skip**  
+`_ = sendUDP(...)` sites carry justifying comments (`errors.md`). `gofmt`/layout not reviewed. `App` pass-through methods are required by ADR `0001-wails-station-window.md` (overrides Middle Man).
+
+### Baseline smells (all judgement)
+
+**Divergent Change** — `station.Station` / `session.go`: connection, TX, Opus, UDP, UI state, logging in one type.
+
+**Data Clumps** — `onTCP` / `onServerInfo` pass `udpCh`, `udpErr`, `udpReady`, `udpRx`, `lastTCP` as pointers together.
+
+**Duplicated Code** — `audio/device.go` repeats channel-count logic for capture vs playback; `reflector_test.go` reimplements append/parse helpers already in `protocol.go`.
+
+**Mysterious Name** — `loaded`, `fileShape`, `up` / `outage` don’t say what they hold.
+
+**Primitive Obsession** — `State.Connection` as free strings (`"Connecting"` / `"Connected"` / …); session `reason` as `"tcp"`/`"udp"`/`"timer"`.
+
+**Middle Man** — `Fail` → `stop` → `endFatal` (thin hop).
+
+---
+
+## Spec
+
+**Tests:** `GOWORK=off go test ./...` — `station` OK (~10s); `main` / `audio` / `internal/opus` have no tests. `TestConnectsToLabReflector` skips when `127.0.0.1:5300` is down (or `FUNKNETZ_LAB=0`).
+
+### (a) Missing / partial
+
+- **Separate default devices (partial).** Spec: “A device adapter behind the station talks to the operating system’s default input and default output” / US 52. `audio.Start` opens one `malgo.Duplex` device, not independent default input and default output—fails if duplex is unavailable even when separate devices would work.
+- **Broken-JSON wording (partial).** Spec: “quit and say the file could not be read” (US 10). Implementation exits with `could not be read` (no “the file”).
+
+Stories 1–9, 11–50, 53–62, 64–74 and the protocol / log Implementation Decisions look covered at the station seam (config, login, TG select, OPUS, PTT, heartbeats, retries, fatalities, log).
+
+### (b) Scope creep
+
+- **Local reflector lab.** Spec Solution / US 1–74 never ask for Docker or SvxReflector; Testing Decisions: “An in-process reflector double is the stand-in for TCP and UDP.” Diff adds `svxlink-docker/`, `docs/svxlink.md`, and `station/lab_reflector_test.go` (real TCP to `:5300`).
+- **Audio-open fatal.** Spec never defines device-open failure copy. `app.go` calls `Fail("could not open the audio device")`, inventing an English sentence and stopping retries outside US 57–59.
+
+### (c) Looks implemented, looks wrong
+
+- **Duplex vs defaults (same as (a)).** Spec wants default **input and** default **output**; duplex is a different contract and can reject a valid headset/speakers pair.
+- No other clear behavioral mismatches found against US 1–74 / protocol / log rules at HEAD (`8e75515...HEAD`). Wails labels, callsign/TG, PTT OR of button+Space, flush-on-release, busy-room inert PTT, and log line shapes match the quoted decisions.
+
+---
+
+## Protocol deep dive: SvxLink vs funknetz
+
+There is no separate RFC. The contract is SvxLink / jayReflector message types (`ReflectorMsg.h` and client logics). Funknetz targets **protocol 2.0** (ReflectorV2 / AUTH_KEY), matching FM-Funknetz’s published guidance. Background: [docs/research/2026-10-03-fm-funknetz-go-client.md](../../docs/research/2026-10-03-fm-funknetz-go-client.md), lab notes in [docs/svxlink.md](./svxlink.md).
+
+### 1. What funknetz implements
+
+**Framing.** TCP: 4-byte BE length + `uint16` type + body (`station/protocol.go`). UDP V2 header: type, client id, sequence (`station/session.go`). Strings/blobs: `uint16` length + bytes. Max TCP frame 32768.
+
+**TCP types handled or sent** (`protocol.go`, `session.go`, `software.go`):
+
+| Type | Role in funknetz |
+| --- | --- |
+| 5 | Send ProtoVer **2.0** first |
+| 10 / 11 / 12 | HMAC-SHA1 challenge (20 B) → callsign + digest; AuthOK is a no-op |
+| 13 | Fatal string → stop retries |
+| 100 | Parse reserved, client id, nodes, codecs; require `"OPUS"` |
+| 111 | Send NodeInfoV2 JSON `{"sw","swVer"}` only |
+| 106 | Send configured TG once after 111 |
+| 104 / 105 | Talker start/stop: honor only matching TG; own callsign start ignored |
+| 1 | TCP heartbeat |
+
+Unknown TCP types are ignored.
+
+**UDP:** send/recv type **1** heartbeat; **101** audio (`uint16` len + Opus); **102** flush on PTT release (after padding a partial frame). Drop datagrams whose client id ≠ ours; **no** sequence check on RX. While transmitting, discard RX audio.
+
+**Auth / codecs / Opus.** Auth key never on the wire. Opus-only: 16 kHz mono, 320 samples / 20 ms, 20 kbit/s VBR, voice, medium-band, DTX off (`internal/opus/opus.go`).
+
+**Heartbeats / talker rules.** Match ReflectorV2 counters: TCP TX 10 s / RX 15 s; UDP TX 15 s / RX 60 s. Room busy from talker-start (matching TG) or any accepted RX audio; PTT inert while busy; mic never looped to playback.
+
+**Tests assert:** login ProtoVer 2.0, HMAC digest, NodeInfo keys, SelectTG, initial UDP HB seq 0; heartbeats, retries, MsgError / no-OPUS stop retry, TCP/UDP timeouts, TG-filtered talker, busy blocks TX, PTT + flush 102, seq wrap, wrong-client-id audio dropped.
+
+### 2. Parity with SvxLink ReflectorV2
+
+| Capability | Upstream (ReflectorV2 / research) | funknetz |
+| --- | --- | --- |
+| Proto 2.0 + AUTH_KEY HMAC-SHA1 | ReflectorV2Logic | Yes |
+| Framed TCP + UDP same host/port | AsyncFramedTcp / V2 UDP | Yes |
+| MsgServerInfo → client id + codecs | type 100 | Yes (OPUS required) |
+| MsgSelectTG | 106 | Yes |
+| MsgNodeInfoV2 | 111 JSON | Yes (minimal) |
+| TalkerStart/Stop with TG | 104 / 105 (≥ proto 2) | Yes |
+| UDP HB / Audio / FlushSamples | 1 / 101 / 102 | Yes |
+| One talker/TG; client mute when busy | Reflector + client | Client-side busy |
+| Heartbeat timers 10 / 15 / 15 / 60 | ReflectorV2Logic.h | Yes |
+| Opus defaults 16 kHz / 20 ms / 20 kbit | AsyncAudioEncoderOpus | Yes |
+
+### 3. Differences
+
+**Intentional (spec Out of Scope):** protocol 3 / certs / AES-GCM UDP; MsgTgMonitor / QSY / DTMF; DNS SRV / baked-in host; GSM / Speex / RAW; rich node-info; multi-TG; station list / siglev UI.
+
+**Thinner than ReflectorV2 client:**
+
+| Topic | Upstream V2 | funknetz |
+| --- | --- | --- |
+| MsgProtoVerDowngrade (6) | Client should retry lower ver | Ignored |
+| RX UDP sequence / peer filter | Drop behind-seq; peer = TCP peer | Client-id only; connected UDP socket |
+| MsgUdpAllSamplesFlushed (103) | Flush handshake | Not sent/handled |
+| TalkerStop vs late audio | Audio may still arrive after 105 | Stop clears busy; **any later 101 re-sets `roomBusy`** without a named talker (`session.go` `onDatagram`) — can strand PTT |
+| Pre-auth size cap | 64 B | Always up to 32768 |
+| MONITOR_TGS / StateEvent / Signal / TxStatus | Optional client telemetry | Absent |
+| Codecs | First mutually supported | Hard-fail if no OPUS |
+| jayReflector type 121 trunk node list | Extra | Ignored (OK) |
+
+### 4. Currently missing
+
+**(A) Intentionally out of scope for v1 headset** — Proto 3 / encryption; MsgTgMonitor; MsgRequestQsy; NodeJoined / Left UI; StateEvent / SignalStrength / TxStatus; DNS SRV; non-OPUS codecs; rich NODE_INFO; multi-TG.
+
+**(B) Gaps that can still affect ReflectorV2 / FM-Funknetz / jayReflector headset use**
+
+1. **Late audio after TalkerStop** re-busying the room without a named talker (upstream documents post-stop audio).
+2. **No ProtoVerDowngrade** handling (unlikely on FM’s V2 servers; breaks if a server asks to step down).
+3. **No UDP flush / all-flushed** — usually fine for app clients; edge cases if a peer expects 103.
+4. **No SRV** — operators must set host/port (FM docs often use 5308 + `DNS_DOMAIN` on nodes).
+5. **No MsgTgMonitor** — idle monitoring of other TGs unavailable; single SelectTG is enough for one configured TG.
+6. **Stricter RX sequence** not implemented — more permissive than V2; rarely blocks interop.
+
+Core login + SelectTG + Opus UDP path is aligned with FM-Funknetz’s ReflectorV2 guidance.
+
+### 5. Lab stack
+
+| Stack | Role |
+| --- | --- |
+| **funknetz `svxlink-docker`** | Builds **jayReflector** → `svxreflector`; TCP+UDP **5300**; `[USERS]` / `[PASSWORDS]` for proto 2; optional **Satellite** (outbound **5303**) / **Trunk** (**5302**); clients stay on local `:5300` |
+| **Stock sm0svx SvxReflector** | Same client wire protocol; **no** reflector peering |
+| **jayReflector Satellite / Trunk** | Server-side mesh / uplink; Funknetz does **not** speak Trunk / Satellite |
+
+Headset interop testing needs a ReflectorV2-capable `svxreflector` with OPUS and AUTH_KEY users. Satellite / Trunk only matter when exercising FM uplink, not the client protocol itself.
+
+### Message coverage (quick map)
+
+| Direction | Implemented | Not implemented (by design unless noted) |
+| --- | --- | --- |
+| TCP send | 5, 11, 1, 111, 106 | 14–21 (proto 3), 107 monitor, 109 QSY, 110–113 telemetry |
+| TCP recv | 1, 10, 12, 13, 100, 104, 105 | 6 downgrade (**gap**), 101 NodeList (legacy), 102/103 presence, 114 UDP encrypt |
+| UDP send | 1, 101, 102 | 103 all-flushed, 104 signal |
+| UDP recv | 1 (timer), 101 | sequence validation, 102/103 handshake |
+
+---
+
+## Summary
+
+**Standards:** 3 hard findings (json/v2 in `software.go`; bare `could not be read` dropping causes; `panic` in test helpers); several judgement smells — worst hard issue is inconsistent JSON API / dropped error causes on config read.  
+**Spec:** 2 partial gaps (duplex vs separate default devices; broken-JSON wording) + 2 scope-creep items (Docker lab; audio-open fatal copy) — worst issue is duplex audio vs the specified separate default input/output devices.
+
+### Follow-up (2026-10-07)
+
+Hard Standards and Spec gaps addressed in code where possible:
+
+| Finding | Status |
+| --- | --- |
+| `software.go` → `encoding/json/v2` | Fixed |
+| Config / path errors wrap with `%w`; US 10 wording `the file could not be read` | Fixed |
+| Test helpers use `t.Fatal` instead of `panic` | Fixed |
+| Separate default Capture + Playback devices (not Duplex) | Fixed |
+| Docker lab scope creep | Left in place — intentional engineering aid, not a product story |
+| Audio-open `Fail("could not open the audio device")` | Left — spec has no copy; stopping without audio is still required UX |
diff --git a/docs/svxlink.md b/docs/svxlink.md
index d5e9769..f06c4c2 100644
--- a/docs/svxlink.md
+++ b/docs/svxlink.md
@@ -1,29 +1,42 @@
 # SvxLink lab for Funknetz
 
-Funknetz must be proven against a local SvxReflector before it touches the live network. This document is that lab: how to run the reflector, what it will accept from a station, and what the wire protocol actually does—so a headset client can be tested without FM-Funknetz credentials.
+Funknetz must be proven against a local reflector before it touches the live network. This document is that lab: how to run the reflector, what it will accept from a station, and what the wire protocol actually does—so a headset client can be tested without FM-Funknetz credentials.
 
-Upstream SvxLink is two processes with different jobs. `svxlink` is a node: logics, optional radio hardware, modules. `svxreflector` is the conference: stations connect over IP, and it forwards audio among those on the same talk group—one talker at a time. Funknetz is a station on that conference; the lab runs only `svxreflector`. You do not need a full RF node, LocalRx/LocalTx, or EchoLink to exercise the headset client.
+The lab runs **[jayReflector](https://github.com/dj1jay/jayReflector)** (DJ1JAY / FM-Funknetz), a Trunk/Satellite-capable fork of SvxReflector. The process is still named `svxreflector`. You do **not** need the `svxlink` node binary, LocalRx/LocalTx, or EchoLink to exercise the headset client.
+
+Funknetz is a station on the conference: it connects to the local reflector on TCP+UDP. Optional FM-Funknetz uplink is Satellite (outbound) or Trunk — configured separately when DJ1JAY provides parameters.
 
 ## Running a local reflector
 
-Lab compose lives in [`svxlink-docker/`](../svxlink-docker/). It builds upstream SvxLink (community Docker pattern from [f4hlv/svxlink-docker](https://github.com/f4hlv/svxlink-docker)), mounts a minimal `svxreflector.conf`, publishes TCP **and** UDP on the listen port, and runs only `svxreflector`. There is no first-party `sm0svx` image on Docker Hub.
+Lab compose lives in [`svxlink-docker/`](../svxlink-docker/). It builds jayReflector, mounts a minimal `svxreflector.conf`, publishes TCP **and** UDP on the listen port, and runs only `svxreflector`.
 
 ```sh
 cd svxlink-docker
+cp -n .env.example .env   # if needed
 docker compose up -d --build
 ```
 
 | Item | Lab value |
 | --- | --- |
-| Listen port | **5300** TCP **and** UDP (upstream default; FM-Funknetz production uses 5308) |
-| Config | `svxlink-docker/config/svxreflector.conf` → `/etc/svxlink/svxreflector.conf` |
+| Binary | jayReflector → `/usr/bin/svxreflector` |
+| Listen port | **5300** TCP **and** UDP (local clients; FM-Funknetz production client port is often 5308) |
+| Config | `config/svxreflector.conf` → `/etc/svxlink/svxreflector.conf` |
 | Auth (protocol 2.0) | `[USERS]` → `[PASSWORDS]`; station `authKey` matches that secret |
-| Server cert | `[SERVER_CERT] COMMON_NAME=…` required on first start (current upstream bootstraps a local PKI even for AUTH_KEY clients) |
-| Protocol 3 PKI | Material under `/var/lib/svxlink/pki` (compose volume `data/`) |
+| Server cert | `[SERVER_CERT] COMMON_NAME=…` required on first start (PKI under `data/pki` → `/etc/svxlink/pki`) |
 | Codec | Default **OPUS** when compiled in (`CODECS` optional) |
 | Go smoke test | `GOWORK=off go test ./station/ -run TestConnectsToLabReflector -v` (needs libopus; skips if port 5300 is down) |
 
-Point `~/.funknetz.json` at the lab (values match `.env` / the mounted conf; secrets are local-test placeholders):
+### Lab app start
+
+With the reflector already up, from the funknetz repo root:
+
+```sh
+./teststart.sh
+```
+
+That script requires `svxlink-docker/.env` (it will not copy `.env.example`), checks `FUNKNETZ_*` against `config/svxreflector.conf`, writes `svxlink-docker/.funknetz.generated.json` (gitignored), enables logging to `svxlink-docker/logs/funknetz-lab.log`, builds `funknetz.app` if missing or stale, and launches the binary with `-c` pointing at the generated file. The default operator config remains `~/.funknetz.json`; `-c` / `--config` only select another path (same create/rewrite rules). See [ADR 0002](./adr/0002-home-directory-config.md).
+
+Manual lab JSON (values match `.env` / the mounted conf; secrets are local-test placeholders):
 
 ```json
 {
@@ -39,6 +52,39 @@ Point `~/.funknetz.json` at the lab (values match `.env` / the mounted conf; sec
 
 A second station can use callsign `DL0FN-2` with the same auth key. Do not reuse production FM-Funknetz credentials in the lab.
 
+## Optional FM-Funknetz link (Satellite / Trunk)
+
+Default: `ENABLE_FM_LINK=0` — local island only. No network uplink.
+
+When DJ1JAY provides parameters:
+
+1. Edit [`config/svxreflector.link.conf`](../svxlink-docker/config/svxreflector.link.conf) (prefer **Satellite** for home labs).
+2. Set `ENABLE_FM_LINK=1` in `.env`.
+3. `docker compose up -d` (rebuild only if the image changed).
+
+The entrypoint appends the link file after the base conf. Local Funknetz settings (`FUNKNETZ_*`, port 5300) stay the same.
+
+### Satellite (recommended): outbound only
+
+With Satellite, **your container dials out** to the parent on TCP **5303**. The network does **not** open a connection toward you. You do **not** need public DNS, a static IP, or inbound port-forwarding for the uplink. Only your **local** clients need to reach host `:5300` (typically localhost).
+
+```text
+Funknetz ──:5300──► jayReflector (lab) ──outbound :5303──► FM-Funknetz parent
+```
+
+Fill from DJ1JAY (jayReflector README shape):
+
+- `SATELLITE_OF=parent.example.org:5303`
+- `SATELLITE_ID=…`
+- `SATELLITE_SECRET=…`
+- optional `SATELLITE_FILTER=…` for “only some TGs”
+
+### Trunk (only if agreed)
+
+Equal mesh peer: mutual TCP **5302**, matching `[TRUNK_x]` section name and `SECRET`, plus filters (`ALLOW_TGS` / `TG_MAP`). That **does** require the peer to reach your trunk port — not the default lab layout. Prefer Satellite unless DJ1JAY asks for Trunk.
+
+Research baseline: [docs/research/2026-10-07-jayreflector-fm-funknetz.md](../../docs/research/2026-10-07-jayreflector-fm-funknetz.md).
+
 ## What the reflector admits
 
 The binary does not know “Funknetz” or “HamLink.” It admits a station by protocol version, callsign shape, proof of the auth key (or a certificate on protocol 3), and uniqueness of that callsign on the session. App names are never checked. FM-Funknetz’s tickets, issued keys, and the published rule to use ReflectorV2 are **network policy** layered on top of the same knobs—not a separate allowlist inside `svxreflector`.
@@ -53,11 +99,11 @@ The binary does not know “Funknetz” or “HamLink.” It admits a station by
 | Talk group | Optional per-TG `ALLOW` / `ALLOW_MONITOR` regexes after login. |
 | Software / version string | **None.** Optional node-info JSON is for status only. |
 
-For the lab and for production as FM-Funknetz documents it, the station speaks **protocol 2.0** (ReflectorV2): auth key, not certificates. Upstream’s man page treats AUTH_KEY as deprecated for “modern” reflectors; that is a different target than the live network’s written instruction.
+For the lab and for production as FM-Funknetz documents it, the station speaks **protocol 2.0** (ReflectorV2): auth key, not certificates.
 
 ## Wire protocol
 
-There is no separate RFC. The contract is the message types in upstream SvxLink (`ReflectorMsg.h` and the client logics). Control rides **TCP** as length-prefixed frames (4-byte big-endian length, then payload). Audio and UDP keepalives ride **UDP** to the same host and port. Message types are numeric. Protocol **2.0** authenticates with the auth-key HMAC and sends plaintext UDP with a header of type, client id, and sequence. Protocol **3.0** uses X.509/TLS and encrypts UDP (AES-128-GCM). Funknetz targets 2.0.
+There is no separate RFC. The contract is the message types in SvxLink / jayReflector (`ReflectorMsg.h` and the client logics). Control rides **TCP** as length-prefixed frames (4-byte big-endian length, then payload). Audio and UDP keepalives ride **UDP** to the same host and port. Message types are numeric. Protocol **2.0** authenticates with the auth-key HMAC and sends plaintext UDP with a header of type, client id, and sequence. Protocol **3.0** uses X.509/TLS and encrypts UDP (AES-128-GCM). Funknetz targets 2.0.
 
 Typical protocol 2.0 login:
 
@@ -104,18 +150,12 @@ User messages (type ≥ 100) matter only after the session is connected. Unknown
 
 The codec name is negotiated in `MsgServerInfo`, not per audio packet. When Opus is available and `CODECS` is unset, the reflector prefers **OPUS**.
 
-## Linking and talk-group sharing
+## Reflector linking (lab context)
 
-`svxreflector` interconnects **stations** on talk groups. It has no peer-reflector configuration: two reflector processes do not mesh. Upstream has discussed multi-reflector interconnect (GitHub issue #597); it is not shipped in the tree this lab tracks. FM-Funknetz states the same limit and attaches other networks by **talk-group sharing / bridge**—audio continuity on a designated talk-group number, implemented by a **client** present on both sides (typically an extra `svxlink` instance on the server), not by reflector peering.
-
-A Funknetz station only **consumes** a shared talk group (select or monitor it). Creating a bridge on the live network needs coordination with the FM-Funknetz team (loop risk). Named cross-network talk groups in their prose include **2621** (Berlin), **2629** (Sachsen), and possibly **2624**; app ingress paths such as Zello, FRN, and Teamspeak often default to **262**.
-
-| Concept | What it actually is |
+| Concept | What it is in this lab |
 | --- | --- |
-| Reflector peering | **Unsupported.** Not how you join two Verbünde. |
-| `LINKS=` / ReflectorLink | Audio link between logics **inside one** `svxlink` process (e.g. radio ↔ ReflectorLogic). Not two `svxreflector` servers. |
-| `MONITOR_TGS` / select TG | Watching or joining a talk group **on one** reflector. Uses a bridge TG if operators already bridge it; does not create the path. |
-| EchoLink / Zello / FRN / Teamspeak | Alternate **ingress** into FM-Funknetz. Different protocols; EchoLink cannot switch talk groups. |
-| Same reflector, same TG, two stations | Normal conference behavior—not a bridge test. |
-
-To **simulate** sharing locally: run two `svxreflector` instances on distinct ports and users, plus one bridging `svxlink` (two ReflectorLogic sections or two processes) linked so audio crosses on chosen talk groups. Prove with a third station on each side. Exact dual-ReflectorLogic INIs for FM-Funknetz’s production bridge are not published; compose the lab from upstream logic-linking docs.
+| Stock `sm0svx` peering | **Unsupported** — not what we build. |
+| jayReflector **Satellite** | Lab dials parent `:5303`; optional `SATELLITE_FILTER` for some TGs. Outbound only. |
+| jayReflector **Trunk** | Mesh peer on `:5302` with filters / `TG_MAP`. Needs mutual reachability. |
+| `svxlink` dual ReflectorLogic bridge | Not required here; Satellite/Trunk replace that for FM-Funknetz attach. |
+| Same reflector, same TG, two stations | Normal conference — local test without any uplink. |
diff --git a/main.go b/main.go
index 0532571..a122f98 100644
--- a/main.go
+++ b/main.go
@@ -17,7 +17,7 @@ import (
 var assets embed.FS
 
 func main() {
-	st, err := openStation()
+	st, err := openStation(os.Args[1:])
 	if err != nil {
 		fmt.Fprintln(os.Stderr, err.Error())
 		os.Exit(1)
diff --git a/station/behavior_test.go b/station/behavior_test.go
index 827846c..0c9e6f2 100644
--- a/station/behavior_test.go
+++ b/station/behavior_test.go
@@ -31,9 +31,9 @@ func login(t *testing.T, callsign, key string, tg int, id uint16, codecs []strin
 func loginLog(t *testing.T, callsign, key string, tg int, id uint16, codecs []string, logPath string) loggedIn {
 	t.Helper()
 	refl := newReflector(t)
-	file := configJSON("127.0.0.1", refl.port, callsign, key, tg)
+	file := configJSON(t, "127.0.0.1", refl.port, callsign, key, tg)
 	if logPath != "" {
-		file = configWithLog("127.0.0.1", refl.port, callsign, key, tg, logPath)
+		file = configWithLog(t, "127.0.0.1", refl.port, callsign, key, tg, logPath)
 	}
 	path := writeConfigFile(t, file)
 	clock := newFakeClock()
@@ -151,7 +151,7 @@ func TestRefusedConnectionRetriesUntilQuit(t *testing.T) {
 	port := ln.Addr().(*net.TCPAddr).Port
 	ln.Close()
 
-	path := writeConfigFile(t, configJSON("127.0.0.1", port, "DL1ABC", "key", 4))
+	path := writeConfigFile(t, configJSON(t, "127.0.0.1", port, "DL1ABC", "key", 4))
 	clock := newFakeClock()
 	st, err := station.New(station.Options{ConfigPath: path, Clock: clock})
 	if err != nil {
@@ -196,7 +196,7 @@ func TestReflectorErrorStopsRetries(t *testing.T) {
 	for _, msg := range []string{"Access denied", "no such station"} {
 		t.Run(msg, func(t *testing.T) {
 			refl := newReflector(t)
-			path := writeConfigFile(t, configJSON("127.0.0.1", refl.port, "DL1ABC", "key", 20))
+			path := writeConfigFile(t, configJSON(t, "127.0.0.1", refl.port, "DL1ABC", "key", 20))
 			clock := newFakeClock()
 			st, err := station.New(station.Options{ConfigPath: path, Clock: clock})
 			if err != nil {
@@ -230,7 +230,7 @@ func TestReflectorErrorStopsRetries(t *testing.T) {
 
 func TestMissingOpusStopsRetries(t *testing.T) {
 	refl := newReflector(t)
-	path := writeConfigFile(t, configJSON("127.0.0.1", refl.port, "DL1ABC", "key", 20))
+	path := writeConfigFile(t, configJSON(t, "127.0.0.1", refl.port, "DL1ABC", "key", 20))
 	clock := newFakeClock()
 	st, err := station.New(station.Options{ConfigPath: path, Clock: clock})
 	if err != nil {
diff --git a/station/config.go b/station/config.go
index 21bc583..d6c8bd3 100644
--- a/station/config.go
+++ b/station/config.go
@@ -1,7 +1,9 @@
 package station
 
 import (
+	"errors"
 	"fmt"
+	"io/fs"
 	"math"
 	"os"
 	"path/filepath"
@@ -48,13 +50,13 @@ var callsignPattern = regexp.MustCompile(`^[A-Z0-9][A-Z]{0,2}\d[A-Z0-9]{0,3}[A-Z
 func loadConfig(path string) (loaded, error) {
 	body, err := os.ReadFile(path)
 	if err != nil {
-		if os.IsNotExist(err) {
+		if errors.Is(err, fs.ErrNotExist) {
 			if err := writeTemplate(path); err != nil {
 				return loaded{}, err
 			}
 			return loaded{}, fmt.Errorf("created %s", path)
 		}
-		return loaded{}, fmt.Errorf("could not be read")
+		return loaded{}, fmt.Errorf("the file could not be read: %w", err)
 	}
 	return parseConfig(path, body)
 }
@@ -83,7 +85,7 @@ func writeTemplate(path string) error {
 func parseConfig(path string, body []byte) (loaded, error) {
 	var shape fileShape
 	if err := jsonv2.Unmarshal(body, &shape); err != nil {
-		return loaded{}, fmt.Errorf("could not be read")
+		return loaded{}, fmt.Errorf("the file could not be read: %w", err)
 	}
 	if block, notice := blockedLog(shape); block {
 		cfg, err := parseOperational(shape)
@@ -99,7 +101,7 @@ func parseConfig(path string, body []byte) (loaded, error) {
 		}
 		shape = withLogDefaults(shape)
 		if err := rewriteConfig(path, shape); err != nil {
-			return loaded{}, fmt.Errorf("could not be read")
+			return loaded{}, fmt.Errorf("the file could not be read: %w", err)
 		}
 	}
 	cfg, err := parseOperational(shape)
diff --git a/station/config_test.go b/station/config_test.go
index bca58f2..f40134c 100644
--- a/station/config_test.go
+++ b/station/config_test.go
@@ -84,32 +84,41 @@ func TestExistingConfigIsNotRewritten(t *testing.T) {
 
 func TestInvalidConfigNamesTheField(t *testing.T) {
 	tests := []struct {
-		name string
-		body string
-		want string
+		name      string
+		host      string
+		port      int
+		callsign  string
+		authKey   string
+		talkGroup int
+		body      string
+		want      string
 	}{
-		{name: "empty host", body: configJSON("", 5308, "DL1ABC", "key", 1), want: "host is empty"},
-		{name: "blank host", body: configJSON("   ", 5308, "DL1ABC", "key", 1), want: "host is empty"},
+		{name: "empty host", host: "", port: 5308, callsign: "DL1ABC", authKey: "key", talkGroup: 1, want: "host is empty"},
+		{name: "blank host", host: "   ", port: 5308, callsign: "DL1ABC", authKey: "key", talkGroup: 1, want: "host is empty"},
 		{name: "host type", body: `{"host":1,"port":5308,"callsign":"DL1ABC","authKey":"key","talkGroup":1}`, want: "host has the wrong type"},
-		{name: "empty callsign", body: configJSON("127.0.0.1", 5308, "", "key", 1), want: "callsign is empty"},
+		{name: "empty callsign", host: "127.0.0.1", port: 5308, callsign: "", authKey: "key", talkGroup: 1, want: "callsign is empty"},
 		{name: "callsign type", body: `{"host":"127.0.0.1","port":5308,"callsign":1,"authKey":"key","talkGroup":1}`, want: "callsign has the wrong type"},
-		{name: "empty auth key", body: configJSON("127.0.0.1", 5308, "DL1ABC", "", 1), want: "authKey is empty"},
-		{name: "whitespace auth key", body: configJSON("127.0.0.1", 5308, "DL1ABC", " \t", 1), want: "authKey is empty"},
+		{name: "empty auth key", host: "127.0.0.1", port: 5308, callsign: "DL1ABC", authKey: "", talkGroup: 1, want: "authKey is empty"},
+		{name: "whitespace auth key", host: "127.0.0.1", port: 5308, callsign: "DL1ABC", authKey: " \t", talkGroup: 1, want: "authKey is empty"},
 		{name: "auth key type", body: `{"host":"127.0.0.1","port":5308,"callsign":"DL1ABC","authKey":1,"talkGroup":1}`, want: "authKey has the wrong type"},
-		{name: "port zero", body: configJSON("127.0.0.1", 0, "DL1ABC", "key", 1), want: "port is invalid"},
-		{name: "port negative", body: configJSON("127.0.0.1", -1, "DL1ABC", "key", 1), want: "port is invalid"},
-		{name: "port too high", body: configJSON("127.0.0.1", 65536, "DL1ABC", "key", 1), want: "port is invalid"},
+		{name: "port zero", host: "127.0.0.1", port: 0, callsign: "DL1ABC", authKey: "key", talkGroup: 1, want: "port is invalid"},
+		{name: "port negative", host: "127.0.0.1", port: -1, callsign: "DL1ABC", authKey: "key", talkGroup: 1, want: "port is invalid"},
+		{name: "port too high", host: "127.0.0.1", port: 65536, callsign: "DL1ABC", authKey: "key", talkGroup: 1, want: "port is invalid"},
 		{name: "port type", body: `{"host":"127.0.0.1","port":"5308","callsign":"DL1ABC","authKey":"key","talkGroup":1}`, want: "port has the wrong type"},
 		{name: "port fraction", body: `{"host":"127.0.0.1","port":5308.5,"callsign":"DL1ABC","authKey":"key","talkGroup":1}`, want: "port is invalid"},
-		{name: "talk group zero", body: configJSON("127.0.0.1", 5308, "DL1ABC", "key", 0), want: "talkGroup is invalid"},
-		{name: "talk group negative", body: configJSON("127.0.0.1", 5308, "DL1ABC", "key", -3), want: "talkGroup is invalid"},
+		{name: "talk group zero", host: "127.0.0.1", port: 5308, callsign: "DL1ABC", authKey: "key", talkGroup: 0, want: "talkGroup is invalid"},
+		{name: "talk group negative", host: "127.0.0.1", port: 5308, callsign: "DL1ABC", authKey: "key", talkGroup: -3, want: "talkGroup is invalid"},
 		{name: "talk group type", body: `{"host":"127.0.0.1","port":5308,"callsign":"DL1ABC","authKey":"key","talkGroup":"20"}`, want: "talkGroup has the wrong type"},
-		{name: "bad callsign", body: configJSON("127.0.0.1", 5308, "HELLO", "key", 1), want: "callsign is invalid"},
+		{name: "bad callsign", host: "127.0.0.1", port: 5308, callsign: "HELLO", authKey: "key", talkGroup: 1, want: "callsign is invalid"},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			body := tt.body
+			if body == "" {
+				body = configJSON(t, tt.host, tt.port, tt.callsign, tt.authKey, tt.talkGroup)
+			}
 			path := filepath.Join(t.TempDir(), "funknetz.json")
-			if err := os.WriteFile(path, []byte(tt.body), 0o600); err != nil {
+			if err := os.WriteFile(path, []byte(body), 0o600); err != nil {
 				t.Fatal(err)
 			}
 			before, err := os.ReadFile(path)
@@ -156,8 +165,8 @@ func TestBrokenConfigSaysTheFileCouldNotBeRead(t *testing.T) {
 	if err == nil {
 		t.Fatal("New() error = nil, want a read failure")
 	}
-	if err.Error() != "could not be read" {
-		t.Fatalf("New() error = %q, want %q", err.Error(), "could not be read")
+	if !strings.Contains(err.Error(), "the file could not be read") {
+		t.Fatalf("New() error = %q, want it to say the file could not be read", err.Error())
 	}
 	if strings.Contains(err.Error(), "callsign") {
 		t.Fatalf("New() error = %q, want no field name", err.Error())
@@ -166,7 +175,7 @@ func TestBrokenConfigSaysTheFileCouldNotBeRead(t *testing.T) {
 
 func TestCallsignIsTrimmedAndUppercased(t *testing.T) {
 	path := filepath.Join(t.TempDir(), "funknetz.json")
-	body := configJSON("  127.0.0.1  ", 5308, "  dl1abc-r  ", "a b", 20)
+	body := configJSON(t, "  127.0.0.1  ", 5308, "  dl1abc-r  ", "a b", 20)
 	if err := os.WriteFile(path, []byte(body), 0o600); err != nil {
 		t.Fatal(err)
 	}
@@ -359,7 +368,8 @@ func TestLogSettingsDoNotStopTheStation(t *testing.T) {
 	})
 }
 
-func configJSON(host string, port int, callsign, authKey string, talkGroup int) string {
+func configJSON(t testing.TB, host string, port int, callsign, authKey string, talkGroup int) string {
+	t.Helper()
 	body, err := jsonv2.Marshal(map[string]any{
 		"host":      host,
 		"port":      port,
@@ -368,12 +378,13 @@ func configJSON(host string, port int, callsign, authKey string, talkGroup int)
 		"talkGroup": talkGroup,
 	})
 	if err != nil {
-		panic(err)
+		t.Fatal(err)
 	}
 	return string(body)
 }
 
-func configWithLog(host string, port int, callsign, authKey string, talkGroup int, logPath string) string {
+func configWithLog(t testing.TB, host string, port int, callsign, authKey string, talkGroup int, logPath string) string {
+	t.Helper()
 	body, err := jsonv2.Marshal(map[string]any{
 		"host":          host,
 		"port":          port,
@@ -384,7 +395,7 @@ func configWithLog(host string, port int, callsign, authKey string, talkGroup in
 		"logFile":       logPath,
 	})
 	if err != nil {
-		panic(err)
+		t.Fatal(err)
 	}
 	return string(body)
 }
diff --git a/station/lab_reflector_test.go b/station/lab_reflector_test.go
index 8e5f1e3..d7f9f1a 100644
--- a/station/lab_reflector_test.go
+++ b/station/lab_reflector_test.go
@@ -31,7 +31,7 @@ func TestConnectsToLabReflector(t *testing.T) {
 	}
 	conn.Close()
 
-	path := writeConfigFile(t, configJSON(labHost, labPort, labCallsign, labAuthKey, labTalkGroup))
+	path := writeConfigFile(t, configJSON(t, labHost, labPort, labCallsign, labAuthKey, labTalkGroup))
 	st, err := station.New(station.Options{ConfigPath: path})
 	if err != nil {
 		t.Fatal(err)
diff --git a/station/log_test.go b/station/log_test.go
index d705908..a34f670 100644
--- a/station/log_test.go
+++ b/station/log_test.go
@@ -123,7 +123,7 @@ func TestLogFailureStaysInTheIdleSlot(t *testing.T) {
 func TestFirstDialFailureIsLoggedOnce(t *testing.T) {
 	logPath := filepath.Join(t.TempDir(), "funknetz.log")
 	ln := listenClosed(t)
-	path := writeConfigFile(t, configWithLog("127.0.0.1", ln, "DL1ABC", "key", 4, logPath))
+	path := writeConfigFile(t, configWithLog(t, "127.0.0.1", ln, "DL1ABC", "key", 4, logPath))
 	clock := newFakeClock()
 	st, err := station.New(station.Options{ConfigPath: path, Clock: clock})
 	if err != nil {
@@ -152,7 +152,7 @@ func TestFirstDialFailureIsLoggedOnce(t *testing.T) {
 func TestReflectorErrorsAreOneLogLine(t *testing.T) {
 	logPath := filepath.Join(t.TempDir(), "funknetz.log")
 	refl := newReflector(t)
-	path := writeConfigFile(t, configWithLog("127.0.0.1", refl.port, "DL1ABC", "key", 20, logPath))
+	path := writeConfigFile(t, configWithLog(t, "127.0.0.1", refl.port, "DL1ABC", "key", 20, logPath))
 	clock := newFakeClock()
 	st, err := station.New(station.Options{ConfigPath: path, Clock: clock})
 	if err != nil {
diff --git a/station/session_test.go b/station/session_test.go
index 6a384c9..1c7d855 100644
--- a/station/session_test.go
+++ b/station/session_test.go
@@ -13,7 +13,7 @@ import (
 
 func TestLoginAnnouncesProtocolAndJoinsTheTalkGroup(t *testing.T) {
 	refl := newReflector(t)
-	path := writeConfigFile(t, configJSON("  127.0.0.1  ", refl.port, "  dl1abc  ", "auth key with spaces", 20))
+	path := writeConfigFile(t, configJSON(t, "  127.0.0.1  ", refl.port, "  dl1abc  ", "auth key with spaces", 20))
 	clock := newFakeClock()
 	st, err := station.New(station.Options{ConfigPath: path, Clock: clock})
 	if err != nil {
diff --git a/station/software.go b/station/software.go
index e39b992..d772f87 100644
--- a/station/software.go
+++ b/station/software.go
@@ -1,6 +1,6 @@
 package station
 
-import "encoding/json"
+import jsonv2 "encoding/json/v2"
 
 // SoftwareName and SoftwareVersion are the identity sent to the reflector
 // after login. Edit them here.
@@ -10,7 +10,7 @@ const (
 )
 
 func softwareIdentityBody() ([]byte, error) {
-	raw, err := json.Marshal(struct {
+	raw, err := jsonv2.Marshal(struct {
 		SW    string `json:"sw"`
 		SWVer string `json:"swVer"`
 	}{
diff --git a/svxlink-docker/.env.example b/svxlink-docker/.env.example
index 1d590c2..97aa552 100644
--- a/svxlink-docker/.env.example
+++ b/svxlink-docker/.env.example
@@ -4,15 +4,16 @@ TZ=Europe/Berlin
 
 LISTEN_PORT=5300
 
-START_SVXLINK=0
-START_REMOTETRX=0
-START_SVXREFLECTOR=1
+# 0 = local lab only (default). 1 = append config/svxreflector.link.conf
+# (Satellite/Trunk from DJ1JAY). Satellite dials out — no public DNS needed.
+ENABLE_FM_LINK=0
 
 SVXREFLECTOR_CONF=/etc/svxlink/svxreflector.conf
+SVXREFLECTOR_LINK_CONF=/etc/svxlink/svxreflector.link.conf
 SVXREFLECTOR_ARGS=--logfile=/var/log/svxlink/svxreflector.log
 
 FUNKNETZ_HOST=127.0.0.1
 FUNKNETZ_PORT=5300
 FUNKNETZ_CALLSIGN=DL0FN-1
 FUNKNETZ_AUTH_KEY=local-lab-secret-change-me
-FUNKNETZ_TALK_GROUP=9
+FUNKNETZ_TALK_GROUP=20
diff --git a/svxlink-docker/.gitignore b/svxlink-docker/.gitignore
index e4d800c..7d0a3f9 100644
--- a/svxlink-docker/.gitignore
+++ b/svxlink-docker/.gitignore
@@ -4,3 +4,7 @@ data/*
 !data/.gitkeep
 .env
 *.log
+.funknetz.generated.json
+# Optional: keep a private link file with real DJ1JAY secrets untracked.
+# The committed config/svxreflector.link.conf is a commented stub only.
+config/svxreflector.link.local.conf
diff --git a/svxlink-docker/Dockerfile b/svxlink-docker/Dockerfile
index ea6f25f..a99083b 100644
--- a/svxlink-docker/Dockerfile
+++ b/svxlink-docker/Dockerfile
@@ -1,77 +1,72 @@
-# Build and run SvxReflector for the Funknetz local lab.
-# Provenance: patterned on f4hlv/svxlink-docker (community); builds from upstream sm0svx/svxlink.
+# Build jayReflector (DJ1JAY / FM-Funknetz) for the Funknetz local lab.
+# Binary name remains svxreflector; Trunk/Satellite are opt-in via config.
+# Upstream pattern: dj1jay/jayReflector Dockerfile (clone + cmake, not stock sm0svx).
 
 # =========================================================
 # STAGE 1 — BUILD
 # =========================================================
-FROM debian:trixie-slim AS builder
+FROM debian:bookworm AS builder
 ENV DEBIAN_FRONTEND=noninteractive
 
 RUN apt-get update && apt-get -y install --no-install-recommends \
     git ca-certificates \
-    cmake g++ make dpkg-dev \
-    libsigc++-2.0-dev libgsm1-dev libpopt-dev tcl8.6-dev \
-    libgcrypt20-dev libspeex-dev libasound2-dev \
-    libopus-dev librtlsdr-dev libjsoncpp-dev \
-    libcurl4-openssl-dev libgpiod-dev libogg-dev \
-    ladspa-sdk libssl-dev \
+    build-essential cmake \
+    libsigc++-2.0-dev libssl-dev libjsoncpp-dev libpopt-dev \
+    libopus-dev libgsm1-dev \
     && rm -rf /var/lib/apt/lists/*
 
-ARG GIT_URL=https://github.com/sm0svx/svxlink.git
-ARG GIT_BRANCH=master
+ARG GIT_URL=https://github.com/dj1jay/jayReflector.git
+ARG GIT_BRANCH=main
+ARG GIT_REF=
 ARG NUM_CORES=4
 
 WORKDIR /build
-RUN git clone --recursive --depth 1 --branch "${GIT_BRANCH}" "${GIT_URL}" svxlink
-WORKDIR /build/svxlink
-
 RUN set -eux; \
-    SVX_VER="$(awk -F= '$1=="SVXSERVER"{gsub(/[[:space:]]/,"",$2); print $2}' src/versions)"; \
-    echo "SVXSERVER version from src/versions: ${SVX_VER}"; \
-    rm -rf build && mkdir -p build && cd build; \
-    cmake \
-      -DCMAKE_INSTALL_PREFIX=/usr \
-      -DCMAKE_INSTALL_SYSCONFDIR=/etc \
-      -DCMAKE_INSTALL_LOCALSTATEDIR=/var \
+    if [ -n "${GIT_REF}" ]; then \
+      git clone --recursive "${GIT_URL}" jayReflector; \
+      cd jayReflector && git checkout "${GIT_REF}"; \
+    else \
+      git clone --recursive --depth 1 --branch "${GIT_BRANCH}" "${GIT_URL}" jayReflector; \
+    fi
+
+WORKDIR /build/jayReflector
+RUN set -eux; \
+    cmake -S src -B build \
+      -DLOCAL_STATE_DIR=/var \
       -DUSE_QT=OFF \
-      -DCMAKE_BUILD_TYPE=Release \
-      -DCPACK_GENERATOR=DEB \
-      -DCPACK_PACKAGE_VERSION="${SVX_VER}" \
-      -DCPACK_DEBIAN_PACKAGE_VERSION="${SVX_VER}" \
-      ../src; \
-    make -j"${NUM_CORES}"; \
-    make package; \
-    ls -lh *.deb
+      -DUSE_ALSA=OFF \
+      -DCMAKE_BUILD_TYPE=Release; \
+    cmake --build build --target svxreflector -j"${NUM_CORES}"
 
 # =========================================================
 # STAGE 2 — RUNTIME
 # =========================================================
-FROM debian:trixie-slim
+FROM debian:bookworm-slim
 ENV DEBIAN_FRONTEND=noninteractive
 
 RUN apt-get update && apt-get -y install --no-install-recommends \
-    adduser init-system-helpers ca-certificates openssl \
-    libasyncaudio1.6t64 libasynccore1.6t64 libasynccpp1.6t64 libcurl4t64 \
-    libgcrypt20 libgsm1 libjsoncpp26 libpopt0 librtlsdr0 \
-    libsigc++-2.0-0v5 libtcl8.6 libgcc-s1 libstdc++6 \
-    libasound2 libgpiod3 libogg0 libopus0 libspeex1 \
+    ca-certificates openssl \
+    libsigc++-2.0-0v5 libssl3 libjsoncpp25 libpopt0 \
+    libopus0 libgsm1 \
     && rm -rf /var/lib/apt/lists/*
 
-COPY --from=builder /build/svxlink/build/*.deb /tmp/svxlink.deb
+COPY --from=builder /build/jayReflector/build/bin/svxreflector /usr/bin/svxreflector
+COPY --from=builder /build/jayReflector/build/lib/lib*.so* /usr/lib/
 
-RUN apt-get update && \
-    apt-get -y install --no-install-recommends /tmp/svxlink.deb && \
-    rm -f /tmp/svxlink.deb && \
-    rm -rf /var/lib/apt/lists/*
-
-RUN mkdir -p /etc/svxlink /var/log/svxlink /var/lib/svxlink && \
+RUN mkdir -p /etc/svxlink /etc/svxlink/pki /var/log/svxlink /var/lib/svxlink && \
+    ldconfig && \
     useradd -r -u 1000 -m -d /home/svx svx || true
 
-ENV SVXLINK_CONF=/etc/svxlink/svxlink.conf \
-    REMOTETRX_CONF=/etc/svxlink/remotetrx.conf \
-    SVXREFLECTOR_CONF=/etc/svxlink/svxreflector.conf
+ENV SVXREFLECTOR_CONF=/etc/svxlink/svxreflector.conf \
+    SVXREFLECTOR_LINK_CONF=/etc/svxlink/svxreflector.link.conf \
+    ENABLE_FM_LINK=0
 
 COPY entrypoint.sh /entrypoint.sh
 RUN chmod +x /entrypoint.sh
 
+# 5300: local Funknetz / SvxLink clients (TCP+UDP)
+# Satellite mode dials out to parent :5303 — no inbound peer port required.
+# Trunk mode would need 5302/tcp inbound; not published by default in compose.
+EXPOSE 5300/tcp 5300/udp
+
 ENTRYPOINT ["/entrypoint.sh"]
diff --git a/svxlink-docker/config/svxreflector.conf b/svxlink-docker/config/svxreflector.conf
index b4e4832..5b8863c 100644
--- a/svxlink-docker/config/svxreflector.conf
+++ b/svxlink-docker/config/svxreflector.conf
@@ -1,6 +1,10 @@
 ###################################################################
-# Local lab SvxReflector for Funknetz (protocol 2.0 / ReflectorV2)
+# Local lab jayReflector for Funknetz (protocol 2.0 / ReflectorV2)
 # Secrets here are placeholders — do not reuse production keys.
+#
+# Standalone by default: local clients only. FM-Funknetz Satellite/Trunk
+# keys live in svxreflector.link.conf and are appended when
+# ENABLE_FM_LINK=1 (see .env and docker-compose).
 ###################################################################
 
 [GLOBAL]
@@ -8,10 +12,13 @@ TIMESTAMP_FORMAT="%c"
 LISTEN_PORT=5300
 TG_FOR_V1_CLIENTS=999
 # CODECS=OPUS
-COMMAND_PTY=/dev/shm/reflector_ctrl
+COMMAND_PTY=/dev/shm/svxreflector_ctrl
+CERT_PKI_DIR=/etc/svxlink/pki/
+# Optional status JSON (publish 8080 in compose if you enable this):
+# HTTP_SRV_PORT=8080
 
-# Newer SvxReflector bootstraps a local PKI even for protocol 2.0 AUTH_KEY clients.
-# COMMON_NAME is required so the server certificate can be generated on first start.
+# jayReflector / modern SvxReflector bootstraps a local PKI even for
+# protocol 2.0 AUTH_KEY clients. COMMON_NAME is required on first start.
 [SERVER_CERT]
 COMMON_NAME=funknetz-lab.local
 SUBJECT_ALT_NAME=DNS:funknetz-lab.local,DNS:localhost,IP:127.0.0.1
diff --git a/svxlink-docker/config/svxreflector.link.conf b/svxlink-docker/config/svxreflector.link.conf
new file mode 100644
index 0000000..c6a5844
--- /dev/null
+++ b/svxlink-docker/config/svxreflector.link.conf
@@ -0,0 +1,41 @@
+###################################################################
+# Optional FM-Funknetz link stub (jayReflector)
+#
+# Default: leave ENABLE_FM_LINK=0 in .env — this file is ignored.
+# When DJ1JAY provides values:
+#   1. Fill ONE of the blocks below (prefer Satellite for home/NAT labs).
+#   2. Set ENABLE_FM_LINK=1 in .env
+#   3. docker compose up -d
+#
+# Satellite (recommended): this reflector dials OUT to the parent on
+# TCP 5303. No public DNS, no inbound peer port, no port-forward required
+# for the link. Local Funknetz clients still use host :5300 only.
+#
+# Trunk: equal mesh peer; needs mutual reachability on TCP 5302 and a
+# matching [TRUNK_x] section name + SECRET on both sides.
+#
+# Do not commit real secrets. Prefer a local override or keep secrets
+# only in your private .env workflow if you copy this file.
+# Docs: docs/research/2026-10-07-jayreflector-fm-funknetz.md
+# README: https://github.com/dj1jay/jayReflector
+###################################################################
+
+# --- Satellite (fill from DJ1JAY; uncomment to use) ---
+# SATELLITE_OF=parent.example.org:5303
+# SATELLITE_ID=lab-yourcall
+# SATELLITE_SECRET="replace-with-secret-from-dj1jay"
+# Only these TGs cross to/from the parent (bidirectional). Omit for all TGs.
+# SATELLITE_FILTER=2621,2629,20
+
+# --- Trunk peer alternative (fill from DJ1JAY; usually leave commented) ---
+# LOCAL_PREFIX=9
+# TRUNK_LISTEN_PORT=5302
+#
+# [TRUNK_LAB_FM]
+# HOST=fm-parent.example.org
+# PORT=5302
+# SECRET="replace-with-agreed-trunk-secret"
+# REMOTE_PREFIX=262
+# ALLOW_TGS=2621,2629,20
+# # TG_MAP=1:2624100
+# MQTT_NAME=Lab-YourCall
diff --git a/svxlink-docker/docker-compose.yml b/svxlink-docker/docker-compose.yml
index 02da971..f5ce23c 100644
--- a/svxlink-docker/docker-compose.yml
+++ b/svxlink-docker/docker-compose.yml
@@ -1,6 +1,9 @@
-# Local SvxReflector lab for Funknetz.
-# Build once, then: docker compose up -d
+# Local jayReflector lab for Funknetz.
+# Build once, then: docker compose up -d --build
 # Connect the app with host/port/callsign/authKey from .env (see FUNKNETZ_*).
+#
+# FM-Funknetz link (optional): fill config/svxreflector.link.conf from DJ1JAY,
+# set ENABLE_FM_LINK=1, recreate. Satellite mode is outbound-only (no DNS/inbound).
 
 services:
   svxreflector:
@@ -8,9 +11,11 @@ services:
       context: .
       dockerfile: Dockerfile
       args:
-        GIT_URL: https://github.com/sm0svx/svxlink.git
-        GIT_BRANCH: master
-    image: funknetz-svxreflector:local
+        GIT_URL: https://github.com/dj1jay/jayReflector.git
+        GIT_BRANCH: main
+        # Optional pin (overrides branch clone when set), e.g.:
+        # GIT_REF: 50997ed21a37c7c05c132eca5ebb07bab4b80fc7
+    image: funknetz-jayreflector:local
     container_name: funknetz-svxreflector
     restart: unless-stopped
     env_file:
@@ -18,16 +23,21 @@ services:
     ports:
       # Host LISTEN_PORT → container 5300 (must match config/svxreflector.conf).
       # Control is TCP; audio and UDP keepalives use the same number.
+      # Satellite uplink uses outbound TCP 5303 — not published here.
       - "${LISTEN_PORT:-5300}:5300/tcp"
       - "${LISTEN_PORT:-5300}:5300/udp"
+      # Optional HTTP /status when HTTP_SRV_PORT=8080 is set in conf:
+      # - "8080:8080/tcp"
+      # Trunk peer only (not needed for Satellite):
+      # - "5302:5302/tcp"
     environment:
       TZ: ${TZ:-Europe/Berlin}
-      START_SVXLINK: ${START_SVXLINK:-0}
-      START_REMOTETRX: ${START_REMOTETRX:-0}
-      START_SVXREFLECTOR: ${START_SVXREFLECTOR:-1}
+      ENABLE_FM_LINK: ${ENABLE_FM_LINK:-0}
       SVXREFLECTOR_CONF: ${SVXREFLECTOR_CONF:-/etc/svxlink/svxreflector.conf}
+      SVXREFLECTOR_LINK_CONF: ${SVXREFLECTOR_LINK_CONF:-/etc/svxlink/svxreflector.link.conf}
       SVXREFLECTOR_ARGS: ${SVXREFLECTOR_ARGS:-}
     volumes:
       - ./config/svxreflector.conf:/etc/svxlink/svxreflector.conf:ro
+      - ./config/svxreflector.link.conf:/etc/svxlink/svxreflector.link.conf:ro
       - ./logs:/var/log/svxlink
-      - ./data:/var/lib/svxlink
+      - ./data/pki:/etc/svxlink/pki
diff --git a/svxlink-docker/entrypoint.sh b/svxlink-docker/entrypoint.sh
index c184f39..0cf65ec 100755
--- a/svxlink-docker/entrypoint.sh
+++ b/svxlink-docker/entrypoint.sh
@@ -1,17 +1,11 @@
 #!/bin/sh
 set -eu
 
-SVXLINK_CONF="${SVXLINK_CONF:-/etc/svxlink/svxlink.conf}"
-REMOTETRX_CONF="${REMOTETRX_CONF:-/etc/svxlink/remotetrx.conf}"
 SVXREFLECTOR_CONF="${SVXREFLECTOR_CONF:-/etc/svxlink/svxreflector.conf}"
-
-START_SVXLINK="${START_SVXLINK:-0}"
-START_REMOTETRX="${START_REMOTETRX:-0}"
-START_SVXREFLECTOR="${START_SVXREFLECTOR:-1}"
-
-SVXLINK_ARGS="${SVXLINK_ARGS:-}"
-REMOTETRX_ARGS="${REMOTETRX_ARGS:-}"
+SVXREFLECTOR_LINK_CONF="${SVXREFLECTOR_LINK_CONF:-/etc/svxlink/svxreflector.link.conf}"
 SVXREFLECTOR_ARGS="${SVXREFLECTOR_ARGS:-}"
+ENABLE_FM_LINK="${ENABLE_FM_LINK:-0}"
+RUNTIME_CONF="/tmp/svxreflector.runtime.conf"
 
 pids=""
 
@@ -24,15 +18,6 @@ die() {
   exit 1
 }
 
-need_file_if_enabled() {
-  enabled="$1"
-  file="$2"
-  name="$3"
-  if [ "$enabled" = "1" ] && [ ! -f "$file" ]; then
-    die "Config for $name not found: $file (expected volume mount)"
-  fi
-}
-
 start_bg() {
   name="$1"
   shift
@@ -70,37 +55,34 @@ stop_all() {
 
 trap 'stop_all; exit 0' INT TERM
 
-if [ "$START_SVXLINK" = "1" ] && ! command -v svxlink >/dev/null 2>&1; then
-  die "svxlink binary not found"
-fi
-if [ "$START_REMOTETRX" = "1" ] && ! command -v remotetrx >/dev/null 2>&1; then
-  die "remotetrx binary not found"
-fi
-if [ "$START_SVXREFLECTOR" = "1" ] && ! command -v svxreflector >/dev/null 2>&1; then
-  die "svxreflector binary not found"
+command -v svxreflector >/dev/null 2>&1 || die "svxreflector binary not found (jayReflector build)"
+[ -f "$SVXREFLECTOR_CONF" ] || die "Config not found: $SVXREFLECTOR_CONF (expected volume mount)"
+
+# Local-only by default. When ENABLE_FM_LINK=1, append the link stub
+# (Satellite or Trunk keys from DJ1JAY) after the base lab conf.
+if [ "$ENABLE_FM_LINK" = "1" ]; then
+  [ -f "$SVXREFLECTOR_LINK_CONF" ] || die "ENABLE_FM_LINK=1 but link config missing: $SVXREFLECTOR_LINK_CONF"
+  {
+    cat "$SVXREFLECTOR_CONF"
+    echo
+    echo "###################################################################"
+    echo "# Appended FM-Funknetz link stub (ENABLE_FM_LINK=1)"
+    echo "###################################################################"
+    cat "$SVXREFLECTOR_LINK_CONF"
+  } >"$RUNTIME_CONF"
+  conf_path="$RUNTIME_CONF"
+  log "FM link enabled: using $SVXREFLECTOR_CONF + $SVXREFLECTOR_LINK_CONF"
+else
+  conf_path="$SVXREFLECTOR_CONF"
+  log "FM link disabled (ENABLE_FM_LINK=0): local lab reflector only"
 fi
 
-need_file_if_enabled "$START_SVXLINK" "$SVXLINK_CONF" "svxlink"
-need_file_if_enabled "$START_REMOTETRX" "$REMOTETRX_CONF" "remotetrx"
-need_file_if_enabled "$START_SVXREFLECTOR" "$SVXREFLECTOR_CONF" "svxreflector"
+# Ensure PKI dir exists for first-start cert bootstrap.
+mkdir -p /etc/svxlink/pki /var/lib/svxlink/pki
 
-if [ "$START_SVXREFLECTOR" = "1" ]; then
-  start_bg "svxreflector" svxreflector --config "$SVXREFLECTOR_CONF" $SVXREFLECTOR_ARGS
-fi
+start_bg "svxreflector" svxreflector --config "$conf_path" $SVXREFLECTOR_ARGS
 
-if [ "$START_REMOTETRX" = "1" ]; then
-  start_bg "remotetrx" remotetrx --config "$REMOTETRX_CONF" $REMOTETRX_ARGS
-fi
-
-if [ "$START_SVXLINK" = "1" ]; then
-  start_bg "svxlink" svxlink --config "$SVXLINK_CONF" $SVXLINK_ARGS
-fi
-
-if ! echo "$pids" | grep -q '[0-9]'; then
-  die "No service enabled. Set START_SVXREFLECTOR=1 (lab default) and/or START_SVXLINK / START_REMOTETRX"
-fi
-
-log "Requested services are running. Waiting…"
+log "jayReflector (svxreflector) is running. Waiting…"
 
 exit_code=0
 for pid in $pids; do
diff --git a/teststart.sh b/teststart.sh
new file mode 100755
index 0000000..271577f
--- /dev/null
+++ b/teststart.sh
@@ -0,0 +1,124 @@
+#!/usr/bin/env bash
+# Build (if needed) and start funknetz against the local svxlink-docker lab.
+# Does not start Docker — run: (cd svxlink-docker && docker compose up -d)
+set -euo pipefail
+
+ROOT="$(cd "$(dirname "$0")" && pwd)"
+LAB="$ROOT/svxlink-docker"
+ENV_FILE="$LAB/.env"
+CONF="$LAB/config/svxreflector.conf"
+GENERATED="$LAB/.funknetz.generated.json"
+LOG_DIR="$LAB/logs"
+LOG_FILE="$LOG_DIR/funknetz-lab.log"
+APP_BIN="$ROOT/build/bin/funknetz.app/Contents/MacOS/funknetz"
+
+die() {
+  echo "teststart: $*" >&2
+  exit 1
+}
+
+[[ -f "$ENV_FILE" ]] || die "missing $ENV_FILE (copy from .env.example and edit; this script will not copy it)"
+
+# shellcheck disable=SC1090
+set -a
+# shellcheck source=/dev/null
+source "$ENV_FILE"
+set +a
+
+missing=()
+[[ -n "${FUNKNETZ_HOST:-}" ]] || missing+=(FUNKNETZ_HOST)
+[[ -n "${FUNKNETZ_PORT:-}" ]] || missing+=(FUNKNETZ_PORT)
+[[ -n "${FUNKNETZ_CALLSIGN:-}" ]] || missing+=(FUNKNETZ_CALLSIGN)
+[[ -n "${FUNKNETZ_AUTH_KEY:-}" ]] || missing+=(FUNKNETZ_AUTH_KEY)
+[[ -n "${FUNKNETZ_TALK_GROUP:-}" ]] || missing+=(FUNKNETZ_TALK_GROUP)
+if ((${#missing[@]})); then
+  die "missing in .env: ${missing[*]}"
+fi
+
+[[ -f "$CONF" ]] || die "missing $CONF"
+
+# Resolve FUNKNETZ_CALLSIGN → password group in [USERS], then secret in [PASSWORDS].
+callsign_upper="$(printf '%s' "$FUNKNETZ_CALLSIGN" | tr '[:lower:]' '[:upper:]')"
+section=""
+password_group=""
+auth_secret=""
+while IFS= read -r line || [[ -n "$line" ]]; do
+  line="${line%%#*}"
+  line="$(printf '%s' "$line" | sed -e 's/^[[:space:]]*//' -e 's/[[:space:]]*$//')"
+  [[ -z "$line" ]] && continue
+  if [[ "$line" =~ ^\[(.+)\]$ ]]; then
+    section="${BASH_REMATCH[1]}"
+    continue
+  fi
+  case "$section" in
+  USERS)
+    key="${line%%=*}"
+    val="${line#*=}"
+    key="$(printf '%s' "$key" | sed -e 's/[[:space:]]*$//' | tr '[:lower:]' '[:upper:]')"
+    val="$(printf '%s' "$val" | sed -e 's/^[[:space:]]*//')"
+    if [[ "$key" == "$callsign_upper" ]]; then
+      password_group="$val"
+    fi
+    ;;
+  PASSWORDS)
+    key="${line%%=*}"
+    val="${line#*=}"
+    key="$(printf '%s' "$key" | sed -e 's/[[:space:]]*$//')"
+    val="$(printf '%s' "$val" | sed -e 's/^[[:space:]]*//' -e 's/^"//' -e 's/"$//')"
+    if [[ -n "$password_group" && "$key" == "$password_group" ]]; then
+      auth_secret="$val"
+    fi
+    ;;
+  esac
+done <"$CONF"
+
+[[ -n "$password_group" ]] || die "callsign $FUNKNETZ_CALLSIGN is not in [USERS] in $CONF"
+[[ -n "$auth_secret" ]] || die "password group $password_group has no [PASSWORDS] entry in $CONF"
+[[ "$FUNKNETZ_AUTH_KEY" == "$auth_secret" ]] || die "FUNKNETZ_AUTH_KEY does not match [PASSWORDS] for $FUNKNETZ_CALLSIGN"
+
+mkdir -p "$LOG_DIR"
+
+# JSON-escape a string value.
+json_str() {
+  python3 -c 'import json,sys; print(json.dumps(sys.argv[1]))' "$1"
+}
+
+host_json="$(json_str "$FUNKNETZ_HOST")"
+call_json="$(json_str "$callsign_upper")"
+key_json="$(json_str "$FUNKNETZ_AUTH_KEY")"
+log_json="$(json_str "$LOG_FILE")"
+
+umask 077
+cat >"$GENERATED" <<EOF
+{
+  "host": $host_json,
+  "port": $FUNKNETZ_PORT,
+  "callsign": $call_json,
+  "authKey": $key_json,
+  "talkGroup": $FUNKNETZ_TALK_GROUP,
+  "enableLogging": true,
+  "logFile": $log_json
+}
+EOF
+chmod 600 "$GENERATED"
+
+needs_build=0
+if [[ ! -x "$APP_BIN" ]]; then
+  needs_build=1
+else
+  newer="$(find "$ROOT" \
+    \( -path "$ROOT/build" -o -path "$ROOT/svxlink-docker" -o -path "$ROOT/.git" \) -prune -o \
+    \( -name '*.go' -o -name 'go.mod' -o -name 'go.sum' -o -name 'wails.json' \) -newer "$APP_BIN" -print \
+    -o -path "$ROOT/frontend/dist/*" -newer "$APP_BIN" -print \
+    2>/dev/null | head -n 1 || true)"
+  [[ -n "$newer" ]] && needs_build=1
+fi
+
+if ((needs_build)); then
+  echo "teststart: building funknetz.app…"
+  (cd "$ROOT" && GOWORK=off wails build)
+  [[ -x "$APP_BIN" ]] || die "build finished but binary missing: $APP_BIN"
+fi
+
+echo "teststart: starting with -c $GENERATED"
+exec "$APP_BIN" -c "$GENERATED"