diff --git a/Documentation/deploy-dev-to-prod.md b/Documentation/deploy-dev-to-prod.md
index 739f258..9d45500 100644
--- a/Documentation/deploy-dev-to-prod.md
+++ b/Documentation/deploy-dev-to-prod.md
@@ -36,7 +36,7 @@ For a typical weekly release, use the orchestrator instead of running each step
    - `smb.user` / `smb.password` — optional; maps `\\host\share` before image sync
    - `backupFile` — optional fixed path; otherwise uses the newest `gallery_dev_data_*.txt` after backup
 
-3. Prerequisites still apply: Docker Desktop running, `docker login gitea.mysuperlab.netcraze.pro`, [`infra/docker/.env.prod`](../infra/docker/.env.prod) present.
+3. Prerequisites still apply: **`npm run dev:web` running** (Vite `:5173` + API `:3451`), Docker Desktop running, `docker login gitea.mysuperlab.netcraze.pro`, [`infra/docker/.env.prod`](../infra/docker/.env.prod) present.
 
 ### Run
 
@@ -56,7 +56,7 @@ npm run devtoprod:release -- -DryRun
 
 | Config step | Maps to runbook |
 |-------------|-----------------|
-| `validateBuild` | Step 0 — `prod:build` + dev `/api/bounds` check |
+| `validateBuild` | Step 0 — `prod:build` + dev `/api/bounds` check (API `:3451` and/or Vite `:5173` proxy) |
 | `gitCommitPush` | Step 1 — `git add`, commit, push |
 | `thumbnails` | Step 2 — `devtoprod:thumbnails` |
 | `backupDev` | Step 3 — `dev:db:backup` |
diff --git a/infra/deploy/devtoprod.config.example.json b/infra/deploy/devtoprod.config.example.json
index 90011b4..08239e9 100644
--- a/infra/deploy/devtoprod.config.example.json
+++ b/infra/deploy/devtoprod.config.example.json
@@ -29,6 +29,7 @@
     "password": ""
   },
   "verify": {
+    "devApiUrl": "http://127.0.0.1:3451/api/bounds",
     "devLanUrl": "http://192.168.10.70:5173/api/bounds",
     "devUrl": "https://devgallery.mysuperlab.netcraze.pro/api/bounds",
     "lanUrl": "http://192.168.10.122:5173/api/bounds",
diff --git a/infra/scripts/deploy-dev-to-prod.ps1 b/infra/scripts/deploy-dev-to-prod.ps1
index a2d9f3f..447abde 100644
--- a/infra/scripts/deploy-dev-to-prod.ps1
+++ b/infra/scripts/deploy-dev-to-prod.ps1
@@ -203,29 +203,57 @@ function Get-LatestDevBackup {
     return $latest.FullName
 }
 
+function Get-DevApiPort {
+    $envFile = Join-Path $RepoRoot '.env'
+    $port = '3451'
+    if (Test-Path $envFile) {
+        foreach ($line in Get-Content -LiteralPath $envFile) {
+            if ($line -match '^\s*PORT\s*=\s*(\d+)\s*$') {
+                $port = $Matches[1]
+                break
+            }
+        }
+    }
+    return $port
+}
+
 function Test-BoundsJson {
     param(
         [string]$Url,
         [switch]$Insecure,
         [int]$MaxTimeSeconds = 10,
-        [int]$Retries = 3
+        [int]$Retries = 3,
+        [ref]$Detail
     )
 
+    $lastDetail = 'no response'
     for ($attempt = 1; $attempt -le $Retries; $attempt++) {
-        $curlArgs = @('-s', '-f', '--max-time', $MaxTimeSeconds)
+        $curlArgs = @('-s', '-w', "`nHTTP_CODE:%{http_code}", '--max-time', $MaxTimeSeconds)
         if ($Insecure) { $curlArgs += '-k' }
         $curlArgs += $Url
 
-        $body = & curl.exe @curlArgs 2>$null
-        if ($LASTEXITCODE -eq 0 -and $body) {
+        $raw = (& curl.exe @curlArgs 2>&1 | Out-String).TrimEnd()
+        $httpCode = $null
+        $body = $raw
+        if ($raw -match '(?s)^(.*)HTTP_CODE:(\d+)\s*$') {
+            $body = $Matches[1].TrimEnd()
+            $httpCode = $Matches[2]
+        }
+
+        if ($httpCode -eq '200' -and $body) {
             try {
                 $json = $body | ConvertFrom-Json
                 if ($null -ne $json.min_year -and $null -ne $json.max_year) {
                     return $true
                 }
+                $lastDetail = 'HTTP 200 but JSON missing min_year/max_year'
             } catch {
-                # Continue retries below.
+                $lastDetail = 'HTTP 200 but response is not valid JSON'
             }
+        } elseif ($httpCode) {
+            $lastDetail = "HTTP $httpCode"
+        } else {
+            $lastDetail = "curl exit $LASTEXITCODE"
         }
 
         if ($attempt -lt $Retries) {
@@ -233,6 +261,7 @@ function Test-BoundsJson {
         }
     }
 
+    if ($Detail) { $Detail.Value = $lastDetail }
     return $false
 }
 
@@ -282,9 +311,13 @@ if (Get-StepEnabled $steps 'validateBuild') {
         if ($code -ne 0) { return $code }
 
         # Dev-only endpoints. Do not use verify.lanUrl here (that is prod on TrueNAS).
+        $devApiPort = Get-DevApiPort
         $devCandidates = @(
+            "http://127.0.0.1:$devApiPort/api/bounds"
+            'http://localhost:5173/api/bounds'
             'http://192.168.10.70:5173/api/bounds'
         )
+        if ($cfg.verify.devApiUrl) { $devCandidates += $cfg.verify.devApiUrl }
         if ($cfg.verify.devLanUrl) { $devCandidates += $cfg.verify.devLanUrl }
         if ($cfg.verify.devUrl) { $devCandidates += $cfg.verify.devUrl }
         $devCandidates = $devCandidates | Select-Object -Unique
@@ -293,16 +326,19 @@ if (Get-StepEnabled $steps 'validateBuild') {
         foreach ($u in $devCandidates) {
             Write-Host "Checking dev /api/bounds: $u"
             $useInsecure = $u.StartsWith('https://', [System.StringComparison]::OrdinalIgnoreCase)
-            if (Test-BoundsJson -Url $u -Insecure:$useInsecure -MaxTimeSeconds 10 -Retries 3) {
+            $detail = ''
+            if (Test-BoundsJson -Url $u -Insecure:$useInsecure -MaxTimeSeconds 10 -Retries 3 -Detail ([ref]$detail)) {
                 Write-Host "Dev API OK: $u"
                 $devOk = $true
                 break
             }
-            Write-Host "Dev API check failed for: $u" -ForegroundColor DarkYellow
+            Write-Host "Dev API check failed for: $u ($detail)" -ForegroundColor DarkYellow
         }
 
         if (-not $devOk) {
             Write-Host "Dev API check failed on all URLs." -ForegroundColor Red
+            Write-Host "Start the full dev stack before release: npm run dev:web" -ForegroundColor Yellow
+            Write-Host "Vite on :5173 alone is not enough - the API must listen on :$devApiPort (PORT in .env)." -ForegroundColor Yellow
             return 1
         }
         return 0