diff --git a/docs/implementation-plan.md b/docs/implementation-plan.md
index e145fc2..0690553 100644
--- a/docs/implementation-plan.md
+++ b/docs/implementation-plan.md
@@ -13,6 +13,8 @@
 - Receiver OBS scene has `Neighbor PC - Video` and `Neighbor PC - Focusrite` Media Sources.
 - Voicemeeter loopback installed on the sender.
 - Receiver OBS scene has `Neighbor PC - System Audio` on SRT port `5102`.
+- Sender script uses `-nostdin` and repo-root logs so desktop launchers stay alive and diagnostics land in `C:\Meta\LocalCastBridge\logs`.
+- Sender video config currently matches the live `1024x768` desktop.
 
 ## Temporary
 
@@ -23,8 +25,8 @@
 
 ## Next
 
-1. Open OBS and confirm the `Neighbor PC - Video` and `Neighbor PC - Focusrite` sources load.
-2. Start the sender from Madman's desktop.
+1. Open OBS and confirm the three `Neighbor PC` sources load.
+2. Start the sender from Madman's interactive desktop, not SSH.
 3. Smoke-test the video endpoint in OBS.
 4. Smoke-test the Focusrite endpoint in OBS.
 5. Smoke-test the system-loopback endpoint in OBS.
diff --git a/docs/neighbor-sender-setup.md b/docs/neighbor-sender-setup.md
index 350ce21..d38e2ed 100644
--- a/docs/neighbor-sender-setup.md
+++ b/docs/neighbor-sender-setup.md
@@ -37,6 +37,11 @@ focusrite srt://192.168.1.66:5101?mode=caller&latency=120000
 system    srt://192.168.1.66:5102?mode=caller&latency=120000
 ```
 
+Current video capture size is `1024x768`, matching the live `WinDisc` display
+reported by the sender. Do not force `1920x1080` unless Windows reports a real
+desktop of that size; `gdigrab` exits when the requested capture rectangle is
+larger than the current desktop.
+
 OBS on the receiver should add listener-mode Media Sources:
 
 ```text
@@ -75,6 +80,7 @@ Start launcher:
 - starts Voicemeeter
 - sets Windows default render to `Voicemeeter VAIO3 Input`
 - sets Windows default capture to `Voicemeeter Out B3`
+- writes FFmpeg logs under `C:\Meta\LocalCastBridge\logs`
 
 Stop launcher:
 
@@ -108,3 +114,18 @@ ffmpeg -hide_banner -f dshow -list_devices true -i dummy
 If Madman cannot hear local audio while LocalCast is running, open Voicemeeter
 and set hardware output `A1` to the intended physical device, probably
 Focusrite speakers/headphones. The stream capture itself is independent of OBS.
+
+## SSH Testing Trap
+
+Do not use an SSH-launched sender process as proof that video capture is broken.
+When launched from SSH, `gdigrab` sees the remote Windows session desktop and
+can fail with `Failed to capture image (error 5)`. The sender video process
+must be launched from Madman's interactive desktop, normally through:
+
+```text
+C:\Users\Madman's Lullaby\Desktop\Start LocalCast Sender.cmd
+```
+
+Attached SSH probes are still useful for audio devices and SRT reachability.
+For example, an attached FFmpeg probe successfully transmitted audio to OBS on
+ports `5101` and `5102`.
diff --git a/notes/fresh-workspace-handoff.md b/notes/fresh-workspace-handoff.md
index 2202e4b..b794863 100644
--- a/notes/fresh-workspace-handoff.md
+++ b/notes/fresh-workspace-handoff.md
@@ -27,12 +27,14 @@ Get-Content .\state\evidence.jsonl -Tail 8
 - Madman's desktop has `Start LocalCast Sender.cmd` and `Stop LocalCast Sender.cmd`.
 - Receiver OBS scene collection has `Neighbor PC - Video`, `Neighbor PC - Focusrite`, and `Neighbor PC - System Audio` Media Sources added.
 - Sender has Voicemeeter plus SoundVolumeView installed for system-output loopback.
+- Sender script was patched after failed transmission: live FFmpeg commands now include `-nostdin`, logs go under `C:\Meta\LocalCastBridge\logs`, and video capture size is `1024x768`.
+- SSH-launched video capture fails with `gdigrab` error 5; test video from Madman's interactive desktop launcher.
 
 ## Current Pressure
 
 The useful next work is real hardware validation:
 
-- open OBS and smoke-test the three configured receiver sources
+- open OBS and smoke-test the three configured receiver sources from Madman's desktop launcher
 - tune latency once streams are live in OBS
 - add a real loopback/virtual audio capture source if system-output audio is required
 
diff --git a/scripts/sender-start.ps1 b/scripts/sender-start.ps1
index 491c275..b2a3f28 100644
--- a/scripts/sender-start.ps1
+++ b/scripts/sender-start.ps1
@@ -5,6 +5,8 @@ param(
 )
 
 $ErrorActionPreference = "Stop"
+$Root = Split-Path -Parent (Split-Path -Parent $PSCommandPath)
+$LogRoot = Join-Path $Root "logs"
 
 function Resolve-ConfigPath {
     param([string]$Path)
@@ -54,6 +56,20 @@ function Format-CommandLine {
     return ($parts -join " ")
 }
 
+function Format-ArgumentList {
+    param([string[]]$Arguments)
+    $parts = @()
+    foreach ($arg in $Arguments) {
+        if ($arg -match '[\s"&?=]') {
+            $escaped = $arg.Replace('"', '\"')
+            $parts += '"' + $escaped + '"'
+        } else {
+            $parts += $arg
+        }
+    }
+    return ($parts -join " ")
+}
+
 function Start-SourceProcess {
     param(
         [string]$Name,
@@ -68,10 +84,11 @@ function Start-SourceProcess {
         return
     }
 
-    New-Item -ItemType Directory -Force ".\logs" | Out-Null
-    $stdout = Join-Path ".\logs" "$Name.out.log"
-    $stderr = Join-Path ".\logs" "$Name.err.log"
-    $process = Start-Process -FilePath $FfmpegPath -ArgumentList $Arguments -RedirectStandardOutput $stdout -RedirectStandardError $stderr -PassThru -WindowStyle Hidden
+    New-Item -ItemType Directory -Force $LogRoot | Out-Null
+    $stdout = Join-Path $LogRoot "$Name.out.log"
+    $stderr = Join-Path $LogRoot "$Name.err.log"
+    $argumentLine = Format-ArgumentList -Arguments $Arguments
+    $process = Start-Process -FilePath $FfmpegPath -ArgumentList $argumentLine -RedirectStandardOutput $stdout -RedirectStandardError $stderr -PassThru -WindowStyle Hidden
     Write-Host "$Name started. PID=$($process.Id) stdout=$stdout stderr=$stderr"
 }
 
@@ -88,6 +105,7 @@ if ($settings.video -and $settings.video.enabled) {
     $videoUrl = Get-SrtUrl -Receiver $settings.receiver -PortOffset ([int]$settings.video.portOffset)
     $videoArgs = @(
         "-hide_banner",
+        "-nostdin",
         "-loglevel", "info",
         "-f", "gdigrab",
         "-framerate", "$($settings.video.framerate)",
@@ -114,6 +132,7 @@ foreach ($audio in @($settings.audioSources)) {
     $audioUrl = Get-SrtUrl -Receiver $settings.receiver -PortOffset ([int]$audio.portOffset)
     $audioArgs = @(
         "-hide_banner",
+        "-nostdin",
         "-loglevel", "info",
         "-f", "dshow",
         "-i", "audio=$($audio.device)",
diff --git a/state/evidence.jsonl b/state/evidence.jsonl
index 011d049..1f78b90 100644
--- a/state/evidence.jsonl
+++ b/state/evidence.jsonl
@@ -4,3 +4,4 @@
 {"ts": "2026-05-18T10:24:49+00:00", "type": "deployment", "status": "ok", "note": "Neighbor sender 192.168.1.84 has LocalCastBridge under C:\\Meta\\LocalCastBridge, FFmpeg 8.1.1 with SRT/h264_nvenc, and desktop start/stop launchers targeting receiver 192.168.1.66 ports 5100/5101."}
 {"ts": "2026-05-18T10:27:41+00:00", "type": "deployment", "status": "ok", "note": "Receiver OBS Untitled scene now has Neighbor PC - Video and Neighbor PC - Focusrite ffmpeg_source Media Sources listening on SRT ports 5100 and 5101; original scene JSON was backed up before edit."}
 {"ts": "2026-05-18T10:52:05+00:00", "type": "deployment", "status": "ok", "note": "Installed Voicemeeter and SoundVolumeView on sender, added system-loopback using DirectShow device Voicemeeter Out B3 on SRT port 5102, and added matching OBS source Neighbor PC - System Audio."}
+{"ts": "2026-05-18T11:38:25+00:00", "type": "fix", "status": "ok", "note": "Transmission failure traced to three issues: stale OBS SRT source state, sender live launcher splitting/closing FFmpeg due Start-Process/stdin handling, and SSH-launched gdigrab seeing a 1024x768 remote desktop with capture error 5. Patched sender-start with quoted argument string, -nostdin, repo-root logs, and set sender video config to 1024x768; OBS restarted and listening on UDP 5100-5102."}
diff --git a/state/map.yaml b/state/map.yaml
index 48d540b..999c3b3 100644
--- a/state/map.yaml
+++ b/state/map.yaml
@@ -49,7 +49,8 @@ current_status:
     First repo scaffold is in place and deployed to the neighbor sender at
     C:\Meta\LocalCastBridge. FFmpeg 8.1.1 with SRT and h264_nvenc is installed
     there, Voicemeeter supplies system-output loopback, Madman's desktop has
-    start/stop launchers, and the receiver OBS scene has matching Media Sources.
+    start/stop launchers, the sender script has launcher-safe FFmpeg arguments
+    and repo-root logs, and the receiver OBS scene has matching Media Sources.
   next_action: >
-    Open OBS, start the sender launcher from Madman's desktop, and smoke-test
-    video, Focusrite audio, and system audio.
+    With OBS open on the receiver, start the sender launcher from Madman's
+    interactive desktop and smoke-test video, Focusrite audio, and system audio.