diff --git a/frontend/src/api/index.js b/frontend/src/api/index.js
index 18cf5150..ec8cdba1 100644
--- a/frontend/src/api/index.js
+++ b/frontend/src/api/index.js
@@ -228,6 +228,18 @@ export const endpointsApi = {
     }
     return api.post(`/endpoints/${assetId}/commands`, body)
   },
+  // Pushes the published agent build to one endpoint. Separate from
+  // enqueueCommand because the server prepares the delivery (packages the
+  // build, seeds the upgrade script) before queueing it as a pinned
+  // run_script; the caller has no script id to pass and must not invent one.
+  enqueueAgentUpgrade(assetId, opts = {}) {
+    const body = {}
+    if (opts.policyoverride) {
+      body.policyoverride = true
+      body.overridereason = opts.overridereason
+    }
+    return api.post(`/endpoints/${assetId}/agentupgrade`, body)
+  },
   listCommands(assetId) {
     return api.get(`/endpoints/${assetId}/commands`)
   },
diff --git a/plugins/computers/frontend/views/PCDetail.vue b/plugins/computers/frontend/views/PCDetail.vue
index a958a62e..ea144433 100644
--- a/plugins/computers/frontend/views/PCDetail.vue
+++ b/plugins/computers/frontend/views/PCDetail.vue
@@ -218,7 +218,7 @@
             :assetid="computer.assetid"
             :accessmethods="computer.accessmethods || []"
           >
-            <template #actions v-if="canRestart || canHoldPolicy">
+            <template #actions v-if="canRestart || canHoldPolicy || (canAgentUpdate && agentBehind)">
               <!-- Admin only, and FIRST in the band. Placing a hold switches OFF
                    automatic policy enforcement, so it sits with the destructive
                    controls rather than with the read-only refresh. Red rather
@@ -233,6 +233,18 @@
               <button v-if="canRestart" @click="confirmRestart"
                       class="btn btn-warning btn-sm"
                       :disabled="restarting">Restart Computer</button>
+              <!-- Only shown when this endpoint is actually behind the
+                   published build, so it is a call to action rather than a
+                   permanent button. Warning-styled: it interrupts the agent
+                   service, but unlike Restart it does not take the machine
+                   down, and it rolls back on failure. -->
+              <button v-if="canAgentUpdate && agentBehind"
+                      @click="confirmAgentUpgrade"
+                      class="btn btn-warning btn-sm"
+                      :title="`Endpoint is on ${agentversion}, published build is ${agentcurrent}`"
+                      :disabled="upgradingAgent">
+                {{ upgradingAgent ? 'Queueing...' : `Update Agent to ${agentcurrent}` }}
+              </button>
             </template>
           </AssetTriageBand>
         </div>
@@ -1246,6 +1258,13 @@ const refreshing = ref(false)
 // enforced again server-side; hiding the button is convenience, not the guard.
 const canCommand = computed(() => authStore.hasPermission('endpoints.command'))
 const canRestart = computed(() => authStore.hasPermission('endpoints.restart'))
+// Replacing the agent is self-modifying the control plane, so it carries its
+// own grant. The server also requires endpoints.runscript, because the upgrade
+// lands as a script push - reflected here so the button does not offer an
+// action the server will refuse.
+const canAgentUpdate = computed(
+  () => authStore.hasPermission('endpoints.agentupdate')
+    && authStore.hasPermission('endpoints.runscript'))
 
 // Break-glass is admin-only and re-checked server-side against the CALLER, so a
 // scoped token cannot inherit it from the admin who minted it. This flag only
@@ -1881,6 +1900,58 @@ const logCollectorVersionNotice = computed(() => {
     + `${reported}. Update the agent on this endpoint to use it.`
 })
 
+// True only when both versions parse AND the endpoint is strictly older than
+// the published build. Silent when nothing is published or either version is a
+// placeholder like '0.0.0-sample' - offering an upgrade off an unreadable
+// version would be a false alarm, and the server applies the same rule.
+const agentBehind = computed(() => {
+  if (!agentversion.value || !agentcurrent.value) return false
+  if (!parseAgentVersion(agentversion.value)) return false
+  if (!parseAgentVersion(agentcurrent.value)) return false
+  return !agentMeetsMinimum(agentversion.value, agentcurrent.value)
+})
+
+const upgradingAgent = ref(false)
+
+// Typed confirmation, matching confirmRunScript and the destructive Corporate
+// Tools: this stops the SYSTEM service that IS the command channel and swaps it
+// underneath itself. An OK button is too easy to hit for something that, if it
+// goes wrong, takes remote management of the machine with it. The prompt names
+// BOTH versions so the operator can see exactly what is being replaced.
+async function confirmAgentUpgrade() {
+  if (!computer.value?.assetid) return
+  const label = computer.value?.assetnumber || computer.value?.name || 'this PC'
+  const typed = prompt(`Update the ShopDB agent on ${label}?\n\n`
+    + `${agentversion.value} will be replaced with ${agentcurrent.value}.\n`
+    + 'The agent service stops and restarts, so this endpoint will briefly '
+    + 'stop reporting. If the upgrade fails the agent rolls back to the '
+    + 'current build.\n\nType UPDATE to confirm.')
+  if (typed !== 'UPDATE') return
+
+  upgradingAgent.value = true
+  try {
+    const response = await endpointsApi.enqueueAgentUpgrade(computer.value.assetid)
+    // "Queued", not "updated": the agent collects this on its next check-in and
+    // the swap happens afterwards. Claiming success here would assert an
+    // outcome nothing has observed.
+    toast.success(`Agent update queued for ${label}`)
+
+    const commandId = response?.data?.data?.endpointcommandid
+    if (commandId) {
+      await waitForCommand(commandId)
+      // Re-read liveness so the version and the behind flag reflect what the
+      // endpoint now reports, rather than leaving a stale "behind" badge on a
+      // machine that just upgraded.
+      await loadLiveness(computer.value.assetid)
+      await assetPanels.value?.refresh()
+    }
+  } catch (error) {
+    toast.error(apiError(error, `Failed to queue the agent update for ${label}`))
+  } finally {
+    upgradingAgent.value = false
+  }
+}
+
 // History for this endpoint. Metadata only - bodies are fetched one at a time,
 // because 20 rows of multi-hundred-KB logs would make opening the tab far more
 // expensive than reading the one log that is actually wanted.
diff --git a/plugins/endpoints/api/agentregistry.py b/plugins/endpoints/api/agentregistry.py
index abf9a9c7..a15bf964 100644
--- a/plugins/endpoints/api/agentregistry.py
+++ b/plugins/endpoints/api/agentregistry.py
@@ -38,6 +38,15 @@ def _package_path(appid):
     return os.path.join(directory, str(appid), AGENT_PACKAGE_FILENAME)
 
 
+def get_agent_application():
+    """The reserved agent Application row, or None when nothing is registered.
+
+    Read-only lookup for callers that need the appid to build a delivery URL
+    without causing a row to spring into existence as a side effect.
+    """
+    return Application.query.filter_by(appname=AGENT_APPNAME).first()
+
+
 def _get_or_create_app():
     """Return the reserved agent Application row, creating it when absent.
 
diff --git a/plugins/endpoints/api/agentupgradescript.py b/plugins/endpoints/api/agentupgradescript.py
new file mode 100644
index 00000000..8895a62c
--- /dev/null
+++ b/plugins/endpoints/api/agentupgradescript.py
@@ -0,0 +1,136 @@
+"""Seed the agent self-upgrade script into the ShopDB script library.
+
+run_script only delivers bodies that live in the script library, pinned by
+SHA-256. The upgrade template therefore has to exist as a real Script row with
+a stored body before any upgrade can be pushed.
+
+The template is source-controlled at
+plugins/endpoints/api/templates/upgrade-shopdbagent.ps1 and seeded from there
+rather than typed into the library by hand, so the reviewed script and the one
+endpoints actually run are the same artifact. Editing the row's body in the UI
+is pointless - the next seed overwrites it.
+
+It lives under the plugin, not under agent/, because the Docker image copies
+shopdb/, plugins/, migrations/ and scripts/ but NOT agent/. A template read
+from agent/ resolves fine on a developer checkout and then fails in the
+deployed container, which is the worst place to discover it.
+
+One placeholder is rendered at seed time: the agent application's appid, which
+only exists once agentregistry has created the row. Rendering happens BEFORE
+the digest is computed, so the stored body and its sha256 always agree; a
+substitution done after hashing would fail the agent's verification.
+"""
+
+import hashlib
+import os
+
+from shopdb.api import Script, db, script_body_location
+
+from . import agentregistry
+
+# Reserved script name. Unique in the library, which makes seeding idempotent
+# and keeps a hand-made script from colliding with the managed one.
+UPGRADE_SCRIPT_NAME = 'ShopDB Endpoint Agent Self-Upgrade'
+
+_UPGRADE_DESCRIPTION = (
+    'Managed: downloads the current published agent bundle and replaces the '
+    'installed agent in place, then restarts the service. Seeded from source '
+    'control - edits here are overwritten.'
+)
+
+# Substituted with the agent application's appid so the script can fetch its
+# payload from the existing collector-authenticated app-package route.
+_APPID_TOKEN = '{{AGENT_APPID}}'
+
+_TEMPLATE_FILENAME = 'upgrade-shopdbagent.ps1'
+
+
+def template_path():
+    return os.path.join(os.path.dirname(os.path.abspath(__file__)),
+                        'templates', _TEMPLATE_FILENAME)
+
+
+def _script_dir():
+    """Where script bodies live. Resolved through the contract surface helper
+    so this cannot drift from the directory the download route serves from."""
+    directory, _prefix = script_body_location()
+    return directory
+
+
+def render_template(appid):
+    """Return the upgrade script body with the appid substituted.
+
+    Raises if the placeholder is missing: that means the template was edited
+    in a way that breaks the download, and seeding a script that would fetch
+    from a literal '{{AGENT_APPID}}' path is worse than refusing.
+    """
+    with open(template_path(), 'r', encoding='utf-8') as handle:
+        body = handle.read()
+    if _APPID_TOKEN not in body:
+        raise ValueError(
+            'upgrade template is missing the {} placeholder; refusing to seed '
+            'a script that cannot resolve its package'.format(_APPID_TOKEN))
+    return body.replace(_APPID_TOKEN, str(appid))
+
+
+def seed_upgrade_script():
+    """Create or refresh the managed upgrade script row and its body.
+
+    Returns a dict describing the seeded script, or None when the agent
+    application row does not exist yet (nothing to point the download at).
+    Idempotent: unchanged input rewrites nothing and leaves the digest alone.
+    """
+    app = agentregistry.get_agent_application()
+    if app is None:
+        return None
+
+    body = render_template(app.appid).encode('utf-8')
+    digest = hashlib.sha256(body).hexdigest()
+
+    script = Script.query.filter_by(scriptname=UPGRADE_SCRIPT_NAME).first()
+    created = script is None
+    if created:
+        script = Script(
+            scriptname=UPGRADE_SCRIPT_NAME,
+            scriptdescription=_UPGRADE_DESCRIPTION,
+            # SYSTEM: the script stops a service, writes into Program Files,
+            # and edits HKLM. None of that is available in a user context.
+            runcontext='system',
+            # Failures always report; success is opt-in. Capture it here
+            # because an upgrade that "succeeded" but rolled back internally
+            # is only diagnosable from the transcript.
+            captureoutput=True,
+        )
+        db.session.add(script)
+        db.session.flush()
+
+    # Body filename follows the library convention (script-<id>.ps1) so the
+    # collector download route serves it like any other script.
+    filename = 'script-{}.ps1'.format(script.scriptid)
+    path = os.path.join(_script_dir(), filename)
+
+    unchanged = (script.filename == filename and script.sha256 == digest
+                 and os.path.isfile(path))
+    if not unchanged:
+        os.makedirs(_script_dir(), exist_ok=True)
+        # Temp-then-replace so an interrupted write cannot leave a truncated
+        # body at the path the row's digest already claims to describe.
+        temppath = path + '.tmp'
+        with open(temppath, 'wb') as handle:
+            handle.write(body)
+        os.replace(temppath, path)
+        script.filename = filename
+        script.sha256 = digest
+
+    script.scriptdescription = _UPGRADE_DESCRIPTION
+    db.session.commit()
+
+    return {
+        'scriptid': script.scriptid,
+        'scriptname': script.scriptname,
+        'created': created,
+        'updated': not unchanged,
+        'sha256': digest,
+        'bytes': len(body),
+        'appid': app.appid,
+    }
diff --git a/plugins/endpoints/api/routes.py b/plugins/endpoints/api/routes.py
index 88dcbf25..6b7f8710 100644
--- a/plugins/endpoints/api/routes.py
+++ b/plugins/endpoints/api/routes.py
@@ -569,10 +569,11 @@ def panel_status(asset_id: int):
     # "behind" from a placeholder like '0.0.0-sample' would be a false alarm.
     agentvalue = state.agentversion
     published = agentstore.current_version('agent')
-    if (agentvalue and published
-            and parse_agent_version(agentvalue)
-            and parse_agent_version(published)
-            and not agent_meets_minimum(agentvalue, published)):
+    agentbehind = (agentvalue and published
+                   and parse_agent_version(agentvalue)
+                   and parse_agent_version(published)
+                   and not agent_meets_minimum(agentvalue, published))
+    if agentbehind:
         agentvalue = '{} (behind {})'.format(agentvalue, published)
 
     fields = [
@@ -609,7 +610,17 @@ def panel_status(asset_id: int):
             '{} monitor(s) expected running but not reported: {}'.format(
                 len(drift), names)))
 
-    return success_response({'fields': fields})
+    # Machine-readable companion to the "(behind X)" text above. The UI needs to
+    # decide whether to offer the upgrade action, and parsing that decision back
+    # out of a display string would tie the button to the wording of a label.
+    # Emitted as a sibling of fields so nothing about the existing rendering
+    # changes; an older UI simply ignores it.
+    return success_response({
+        'fields': fields,
+        'agentbehind': bool(agentbehind),
+        'agentversion': state.agentversion,
+        'agentcurrent': published,
+    })
 
 
 @endpoints_bp.route('/asset/<int:asset_id>/hardware', methods=['GET'])
@@ -2975,6 +2986,90 @@ def enqueue_endpoint_command(asset_id: int):
                             message='Command queued', http_code=201)
 
 
+@endpoints_bp.route('/<int:asset_id>/agentupgrade', methods=['POST'])
+@require_permission('endpoints.agentupdate')
+def enqueue_agent_upgrade(asset_id: int):
+    """Push the published agent build to one endpoint.
+
+    Replacing the agent is self-modifying the control plane: the process that
+    receives this command is the one being swapped. It therefore sits behind
+    endpoints.agentupdate rather than endpoints.command or endpoints.deploy -
+    see the permission's rationale in plugin.py.
+
+    This does NOT enqueue directly. It prepares the delivery (packages the
+    current build, seeds/refreshes the upgrade script) and then delegates to
+    enqueue_endpoint_command as a run_script push. Writing a second enqueue
+    path here would duplicate - and eventually drift from - the endpoint lock
+    check, the Configuration Policy gate, stale-command reaping and the
+    at-most-one-in-flight rule. Those are exactly the protections a
+    fleet-wide agent swap must not be the one action to skip.
+
+    Because it lands as run_script, the caller needs endpoints.runscript too
+    (enforced by the delegate as the elevated permission for that action).
+    That is deliberate: this delivers arbitrary SYSTEM PowerShell by the same
+    mechanism as any other script push.
+    """
+    from . import agentregistry, agentupgradescript
+
+    # Refresh the package and the script body from the CURRENT staged build
+    # before queueing, so an upgrade cannot ship a stale payload if the row was
+    # written before the latest upload. Both operations are idempotent.
+    try:
+        registration = agentregistry.register_current_agent_package()
+    except Exception as exc:  # noqa: BLE001 - surfaced, not swallowed
+        db.session.rollback()
+        return error_response(ErrorCodes.VALIDATION_ERROR,
+                              f'Could not package the agent build: {exc}')
+    if registration is None:
+        return error_response(
+            ErrorCodes.VALIDATION_ERROR,
+            'No agent build is published. Upload an agent binary before '
+            'pushing an upgrade.')
+
+    try:
+        seeded = agentupgradescript.seed_upgrade_script()
+    except Exception as exc:  # noqa: BLE001 - surfaced, not swallowed
+        db.session.rollback()
+        return error_response(ErrorCodes.VALIDATION_ERROR,
+                              f'Could not prepare the upgrade script: {exc}')
+    if seeded is None:
+        return error_response(ErrorCodes.VALIDATION_ERROR,
+                              'The agent upgrade script could not be prepared.')
+
+    # Rewrite the request body to the equivalent run_script push and hand it to
+    # the real enqueue route. The policyoverride/overridereason fields are
+    # forwarded untouched so break-glass keeps behaving exactly as it does for
+    # a normal script push, including its admin-role and reason requirements.
+    payload = request.get_json(silent=True) or {}
+    forwarded = {
+        'action': 'run_script',
+        'target': 'script:{}'.format(seeded['scriptid']),
+    }
+    if payload.get('policyoverride'):
+        forwarded['policyoverride'] = True
+        forwarded['overridereason'] = payload.get('overridereason') or ''
+
+    # Swap the parsed JSON for the delegate. Flask caches the parsed body on
+    # the request, so setting the cache is what makes get_json() return this.
+    request._cached_json = (forwarded, forwarded)
+
+    response = enqueue_endpoint_command(asset_id)
+
+    # Audit only a push that actually queued. The delegate returns a non-201
+    # for a lock, a policy denial or an in-flight command, and recording those
+    # as upgrades would put events in the log for pushes that never happened.
+    status = getattr(response, 'status_code', None)
+    if status == 201:
+        AuditLog.log(
+            'created', 'AgentUpgrade', entityid=asset_id,
+            entityname='agent {}'.format(registration['agentversion']),
+            details='agent upgrade queued for asset {} (version {}, script {})'
+                    .format(asset_id, registration['agentversion'],
+                            seeded['scriptid']))
+        db.session.commit()
+    return response
+
+
 @endpoints_bp.route('/monitors/resolved', methods=['GET'])
 def resolved_monitors_for_agent():
     """Agent watch list: the monitors this endpoint should report on.
diff --git a/plugins/endpoints/api/templates/upgrade-shopdbagent.ps1 b/plugins/endpoints/api/templates/upgrade-shopdbagent.ps1
new file mode 100644
index 00000000..a9ec125f
--- /dev/null
+++ b/plugins/endpoints/api/templates/upgrade-shopdbagent.ps1
@@ -0,0 +1,332 @@
+# upgrade-shopdbagent.ps1
+# ShopDB Endpoint Agent SELF-UPGRADE template. Delivered to an endpoint by the
+# run_script command and executed by the agent as SYSTEM.
+#
+# WHY THIS TAKES NO PARAMETERS
+# run_script executes "powershell.exe -File <script>" with no argument list, so
+# there is no channel to pass BaseUrl/CollectorKey in. That is not a problem
+# here: an upgrade by definition targets an endpoint that is ALREADY installed
+# and therefore already holds its own config. This script READS that config and
+# never rewrites it - the values stay exactly as provisioned, so an upgrade can
+# not silently repoint an endpoint at a different server or key. A fresh
+# install is still install-shopdbagent.ps1's job.
+#
+# WHY IT RE-LAUNCHES ITSELF DETACHED
+# The agent process is what runs this script, and the upgrade must stop that
+# same agent to release the lock on shopdbagent.exe (single-file self-contained
+# exes are held open while running). If the script stayed a child of the agent,
+# stopping the service would kill the script mid-copy and leave the install
+# directory half-written. The first pass therefore copies itself to a temp
+# location, relaunches detached, and exits immediately so the agent sees a
+# clean, fast result. All real work happens in the detached second pass.
+#
+# REPORTING
+# Success is NOT reported through the command result - by the time the upgrade
+# succeeds, the agent that would have reported it has been restarted. The new
+# version is confirmed on the next check-in. This script's own transcript is
+# the local record; see $LogFile below.
+
+[CmdletBinding()]
+param(
+	# Set only when the script relaunches itself. Operators never pass this.
+	[switch] $Detached
+)
+
+$ErrorActionPreference = 'Stop'
+
+$ServiceName = 'ShopDbEndpointAgent'
+$InstallDir  = 'C:\Program Files\ShopDB\EndpointAgent'
+$TrayExeName = 'shopdb-endpoint-tray.exe'
+$AgentExeName = 'shopdbagent.exe'
+
+$StateDir = Join-Path $env:ProgramData 'ShopDB\EndpointAgent'
+$WorkDir  = Join-Path $StateDir 'upgrade'
+$LogDir   = Join-Path $StateDir 'logs'
+$LogFile  = Join-Path $LogDir ('upgrade-{0}.log' -f (Get-Date -Format 'yyyyMMdd-HHmmss'))
+
+# Server-relative path of the managed agent bundle. This reuses the EXISTING
+# agent-facing app-package route rather than adding a parallel download: it
+# already authenticates with the collector key and already resolves an
+# application's installpath, which is precisely what upload registration
+# stamped for the agent bundle. The appid is substituted by the server when
+# this template is rendered, because it is assigned when the row is created.
+$PackagePath = '/api/endpoints/apppackage/app/{{AGENT_APPID}}'
+
+function Write-Log {
+	param([string] $Message, [string] $Level = 'INFO')
+	$line = '{0} [{1}] {2}' -f (Get-Date -Format 'yyyy-MM-dd HH:mm:ss'), $Level, $Message
+	Write-Host $line
+	try { Add-Content -Path $LogFile -Value $line -ErrorAction Stop } catch { }
+}
+
+# Read a value from the 64-bit HKLM view explicitly. If this runs under 32-bit
+# PowerShell the HKLM: PSDrive silently redirects to WOW6432Node, where the
+# 64-bit agent's config is not, and the upgrade would look unconfigured.
+function Get-Hklm64Value {
+	param([string] $SubKey, [string] $Name)
+	$base = [Microsoft.Win32.RegistryKey]::OpenBaseKey(
+		[Microsoft.Win32.RegistryHive]::LocalMachine,
+		[Microsoft.Win32.RegistryView]::Registry64)
+	try {
+		$key = $base.OpenSubKey($SubKey)
+		if (-not $key) { return $null }
+		try { return $key.GetValue($Name) } finally { $key.Dispose() }
+	}
+	finally { $base.Dispose() }
+}
+
+# Config resolution mirrors the agent's own order of preference, so the upgrade
+# reaches the same server the agent is actually talking to. Registry first;
+# appsettings.json is the fallback for locked-down hosts (CyberArk/EPM) that
+# gate the HKLM hive against reads.
+function Get-AgentConfig {
+	$baseUrl = Get-Hklm64Value -SubKey 'SOFTWARE\GE\ShopDB' -Name 'BaseUrl'
+	$apiKey  = Get-Hklm64Value -SubKey 'SOFTWARE\GE\ShopDB' -Name 'CollectorKey'
+
+	if ([string]::IsNullOrWhiteSpace($baseUrl) -or [string]::IsNullOrWhiteSpace($apiKey)) {
+		$settings = Join-Path $InstallDir 'appsettings.json'
+		if (Test-Path $settings) {
+			try {
+				$json = Get-Content $settings -Raw | ConvertFrom-Json
+				if ([string]::IsNullOrWhiteSpace($baseUrl)) { $baseUrl = $json.baseurl }
+				if ([string]::IsNullOrWhiteSpace($apiKey))  { $apiKey  = $json.apikey }
+				Write-Log 'read config from appsettings.json (registry unavailable or incomplete)'
+			}
+			catch {
+				Write-Log "could not parse appsettings.json: $($_.Exception.Message)" 'WARN'
+			}
+		}
+	}
+
+	if ([string]::IsNullOrWhiteSpace($baseUrl) -or [string]::IsNullOrWhiteSpace($apiKey)) {
+		throw 'No BaseUrl/CollectorKey found in the registry or appsettings.json. This endpoint does not look installed; run install-shopdbagent.ps1 instead.'
+	}
+	return @{ BaseUrl = $baseUrl.TrimEnd('/'); ApiKey = $apiKey }
+}
+
+# ---------------------------------------------------------------------------
+# First pass: relaunch detached and get out of the way. See header.
+# ---------------------------------------------------------------------------
+if (-not $Detached) {
+	New-Item -ItemType Directory -Force -Path $WorkDir, $LogDir | Out-Null
+	$selfCopy = Join-Path $WorkDir 'upgrade-shopdbagent.ps1'
+	Copy-Item -Path $PSCommandPath -Destination $selfCopy -Force
+
+	# Copied out of the agent's own temp dir on purpose: the delivered script
+	# may be cleaned up by the agent once the command returns, which would
+	# delete this file out from under the detached run.
+	Start-Process -FilePath 'powershell.exe' `
+		-ArgumentList '-NoProfile', '-ExecutionPolicy', 'Bypass', `
+					  '-File', "`"$selfCopy`"", '-Detached' `
+		-WindowStyle Hidden | Out-Null
+
+	Write-Host 'Upgrade handed off to a detached process; this agent will restart shortly.'
+	exit 0
+}
+
+# ---------------------------------------------------------------------------
+# Second pass (detached): the actual upgrade.
+# ---------------------------------------------------------------------------
+New-Item -ItemType Directory -Force -Path $WorkDir, $LogDir | Out-Null
+Write-Log '== ShopDB Endpoint Agent self-upgrade =='
+
+try {
+	$config = Get-AgentConfig
+	Write-Log "server: $($config.BaseUrl)"
+
+	# 1. Download BEFORE stopping anything. A failed download must leave the
+	# running agent untouched rather than stranding the endpoint with a
+	# stopped service and no replacement binaries.
+	$zipPath = Join-Path $WorkDir 'agent-package.zip'
+	if (Test-Path $zipPath) { Remove-Item $zipPath -Force }
+	$url = $config.BaseUrl + $PackagePath
+	Write-Log "downloading package from $url ..."
+
+	# TLS 1.2 explicitly: Windows PowerShell 5.1 still defaults to older
+	# protocols the server will refuse.
+	[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
+	Invoke-WebRequest -Uri $url -Headers @{ 'X-API-Key' = $config.ApiKey } `
+		-OutFile $zipPath -UseBasicParsing -TimeoutSec 600
+
+	$size = (Get-Item $zipPath).Length
+	Write-Log "downloaded $size bytes"
+	if ($size -lt 1MB) {
+		throw "Package is only $size bytes; refusing to install a payload this small."
+	}
+
+	# 2. Unpack to a staging dir and validate the payload BEFORE touching the
+	# install. Expanding straight over Program Files would leave a partially
+	# replaced install if the archive turned out to be short a binary.
+	$stage = Join-Path $WorkDir 'stage'
+	if (Test-Path $stage) { Remove-Item $stage -Recurse -Force }
+	New-Item -ItemType Directory -Force -Path $stage | Out-Null
+	Expand-Archive -Path $zipPath -DestinationPath $stage -Force
+
+	$newAgent = Join-Path $stage $AgentExeName
+	if (-not (Test-Path $newAgent)) {
+		throw "$AgentExeName not found in the downloaded package; aborting before any change."
+	}
+	$newTray = Join-Path $stage $TrayExeName
+	$haveTray = Test-Path $newTray
+	Write-Log ("payload validated (agent{0})" -f $(if ($haveTray) { ' + tray' } else { ', no tray' }))
+
+	# 3. Keep the current binaries so a failed swap can be undone. The config
+	# files are deliberately NOT part of this - they are never modified.
+	$backup = Join-Path $WorkDir 'backup'
+	if (Test-Path $backup) { Remove-Item $backup -Recurse -Force }
+	New-Item -ItemType Directory -Force -Path $backup | Out-Null
+	foreach ($name in @($AgentExeName, $TrayExeName)) {
+		$existing = Join-Path $InstallDir $name
+		if (Test-Path $existing) { Copy-Item $existing -Destination $backup -Force }
+	}
+	Write-Log 'backed up current binaries'
+
+	# 4. Stop the service and kill lingering processes. Until this completes
+	# the exes are locked and the copy would fail with a file-in-use error.
+	$svc = Get-Service -Name $ServiceName -ErrorAction SilentlyContinue
+	if ($svc -and $svc.Status -ne 'Stopped') {
+		Write-Log "stopping service $ServiceName ..."
+		try { Stop-Service -Name $ServiceName -Force -ErrorAction Stop }
+		catch { Write-Log "could not stop service: $($_.Exception.Message)" 'WARN' }
+	}
+	$trayBase = [System.IO.Path]::GetFileNameWithoutExtension($TrayExeName)
+	foreach ($name in @('shopdbagent', $trayBase)) {
+		foreach ($p in (Get-Process -Name $name -ErrorAction SilentlyContinue)) {
+			Write-Log "killing $($p.ProcessName) (pid $($p.Id))"
+			try { Stop-Process -Id $p.Id -Force -ErrorAction Stop } catch { }
+		}
+	}
+	Start-Sleep -Milliseconds 750
+
+	# 5. Swap the binaries. On failure, restore the backup and restart, so a
+	# broken upgrade leaves a RUNNING old agent rather than a dead endpoint
+	# that can no longer be reached to fix remotely.
+	try {
+		Copy-Item -Path $newAgent -Destination $InstallDir -Force
+		if ($haveTray) { Copy-Item -Path $newTray -Destination $InstallDir -Force }
+		Write-Log 'binaries replaced'
+	}
+	catch {
+		Write-Log "copy failed: $($_.Exception.Message); rolling back" 'ERROR'
+		Get-ChildItem $backup -File | ForEach-Object {
+			Copy-Item $_.FullName -Destination $InstallDir -Force
+		}
+		Start-Service -Name $ServiceName -ErrorAction SilentlyContinue
+		throw
+	}
+
+	# 6. Clear Mark-of-the-Web. Files extracted from a downloaded archive carry
+	# a Zone.Identifier stream; SmartScreen blocks the unsigned exe on first
+	# run, which would leave the service unable to start.
+	Get-ChildItem -Path $InstallDir -File | ForEach-Object {
+		try { Unblock-File -Path $_.FullName -ErrorAction Stop } catch { }
+	}
+
+	# 7. Restart and verify it stays up. A service that starts and immediately
+	# faults is a failed upgrade, so confirm rather than assume.
+	Write-Log "starting service $ServiceName ..."
+	Start-Service -Name $ServiceName
+	Start-Sleep -Seconds 5
+	$svc = Get-Service -Name $ServiceName -ErrorAction SilentlyContinue
+	if (-not $svc -or $svc.Status -ne 'Running') {
+		Write-Log 'service did not stay running; rolling back' 'ERROR'
+		Get-ChildItem $backup -File | ForEach-Object {
+			Copy-Item $_.FullName -Destination $InstallDir -Force
+		}
+		Start-Service -Name $ServiceName -ErrorAction SilentlyContinue
+		throw 'Upgraded service failed to start; rolled back to the previous build.'
+	}
+
+	$installed = (Get-Item (Join-Path $InstallDir $AgentExeName)).VersionInfo.FileVersion
+	Write-Log "upgrade complete; agent version now $installed"
+
+	# 8. Relaunch the tray for the interactive user.
+	#
+	# This CANNOT use the installer's `explorer.exe <path>` trick. That works in
+	# install-shopdbagent.ps1 only because the installer runs AS THE USER - note
+	# its own guard, `if ($interactiveUser -ne "SYSTEM")`. This script always
+	# runs as SYSTEM in session 0, where `explorer.exe <path>` hands the request
+	# to a shell that is not reachable from here and then exits 0. Start-Process
+	# would report success and we would log a relaunch that never happened,
+	# which is exactly the bug this replaces.
+	#
+	# It also must NOT descend into the session with a token-duplicating launch.
+	# UserContextSpool documents that WTSQueryUserToken is a privileged operation
+	# that endpoint protection blocks on these hardened hosts - the service tried
+	# that direction before and it produced nothing on a live endpoint.
+	#
+	# So the tray is started the same way its own data path is pinned: against
+	# the known ShopFloor account. Task Scheduler performs the session/token
+	# transition, and an Interactive principal with no RunLevel starts the tray
+	# at the user's normal integrity - preserving the de-elevation the installer
+	# wanted, because an elevated unsigned tray trips the CyberArk/EPM broker.
+	#
+	# Best-effort by design: the agent is already upgraded and running, and the
+	# HKLM Run key the installer wrote still starts the tray at next logon. A
+	# late tray is not worth failing - or rolling back - a good agent upgrade.
+	if ($haveTray) {
+		$trayPath = Join-Path $InstallDir $TrayExeName
+		# Same pinned account the spool uses (FileLoggerProvider.ShopFloorUserName):
+		# every shop-floor endpoint signs in as this local account, and the tray
+		# must run as it or the mapped-drive probe reports the wrong account's
+		# (empty) drive table. Only relaunch if that profile is actually present.
+		$trayUser = 'ShopFloor'
+		$trayUserProfile = Join-Path $env:SystemDrive (Join-Path 'Users' $trayUser)
+		if (Test-Path $trayUserProfile) {
+			$taskName = 'ShopDB tray upgrade relaunch'
+			try {
+				# Clear a leftover from an interrupted earlier upgrade so we do
+				# not stack duplicates.
+				if (Get-ScheduledTask -TaskName $taskName -ErrorAction SilentlyContinue) {
+					Unregister-ScheduledTask -TaskName $taskName -Confirm:$false -ErrorAction SilentlyContinue
+				}
+
+				$action = New-ScheduledTaskAction -Execute $trayPath
+				$principal = New-ScheduledTaskPrincipal -UserId $trayUser -LogonType Interactive
+				$settings = New-ScheduledTaskSettingsSet `
+					-AllowStartIfOnBatteries -DontStopIfGoingOnBatteries `
+					-ExecutionTimeLimit ([TimeSpan]::Zero)
+
+				Register-ScheduledTask -TaskName $taskName -Action $action `
+					-Principal $principal -Settings $settings -Force | Out-Null
+				Start-ScheduledTask -TaskName $taskName
+
+				# Verify rather than assume. The old code logged success off a
+				# Start-Process that could not fail, so a missing tray looked
+				# like a clean upgrade. Poll for the real process instead.
+				$trayBaseName = [System.IO.Path]::GetFileNameWithoutExtension($TrayExeName)
+				$running = $null
+				for ($i = 0; $i -lt 10; $i++) {
+					Start-Sleep -Milliseconds 500
+					$running = Get-Process -Name $trayBaseName -ErrorAction SilentlyContinue
+					if ($running) { break }
+				}
+				if ($running) { Write-Log "tray relaunched as $trayUser" }
+				else {
+					Write-Log ('tray did not appear after relaunch; it will start at next ' +
+						'logon via the HKLM Run key') 'WARN'
+				}
+
+				# One-shot hand-off, not a persistent artifact: leaving it would
+				# surface in the uninstaller's leftover sweep and in task audits.
+				Unregister-ScheduledTask -TaskName $taskName -Confirm:$false -ErrorAction SilentlyContinue
+			}
+			catch {
+				Write-Log ("could not relaunch tray: $($_.Exception.Message); " +
+					'it will start at next logon') 'WARN'
+			}
+		}
+		else {
+			Write-Log ("no $trayUser profile at $trayUserProfile; " +
+				'leaving the tray to start at next logon') 'WARN'
+		}
+	}
+
+	Remove-Item $stage -Recurse -Force -ErrorAction SilentlyContinue
+	Remove-Item $zipPath -Force -ErrorAction SilentlyContinue
+	exit 0
+}
+catch {
+	Write-Log "UPGRADE FAILED: $($_.Exception.Message)" 'ERROR'
+	exit 1
+}
diff --git a/shopdb/api/__init__.py b/shopdb/api/__init__.py
index 84fb8fad..88abaade 100644
--- a/shopdb/api/__init__.py
+++ b/shopdb/api/__init__.py
@@ -118,6 +118,20 @@ def application_package_location():
     return _apppackage_dir(), APP_PACKAGE_URL_PREFIX
 
 
+def script_body_location():
+    """Where script bodies live, and the URL prefix that serves them.
+
+    Returns (directory, urlprefix). Same reasoning as
+    application_package_location: a plugin that seeds a script into the
+    library must write the body where the download route reads it from, and
+    reconstructing that path by hand lets the two drift apart silently.
+
+    Imported lazily to avoid the shopdb.core.api -> shopdb.api cycle.
+    """
+    from shopdb.core.api.scripts import _script_dir, SCRIPT_URL_PREFIX
+    return _script_dir(), SCRIPT_URL_PREFIX
+
+
 # Serving an uploaded file safely. A plugin that serves user-supplied bytes must
 # not have to remember the headers that keep an SVG or an HTML file from running
 # as script in this origin - see shopdb/utils/uploads.py.
@@ -408,6 +422,7 @@ __all__ = [
     'revoke_service_tokens',
     'collector_authorized',
     'application_package_location',
+    'script_body_location',
     'SupportTeam',
     # Serving uploads
     'send_upload',
diff --git a/tests/test_plugins/test_endpoints_agent_upgrade_route.py b/tests/test_plugins/test_endpoints_agent_upgrade_route.py
new file mode 100644
index 00000000..96de99ee
--- /dev/null
+++ b/tests/test_plugins/test_endpoints_agent_upgrade_route.py
@@ -0,0 +1,281 @@
+"""The agent self-upgrade enqueue route.
+
+Replacing the agent is self-modifying the control plane: the process that
+receives the command is the one being swapped. The route therefore sits behind
+endpoints.agentupdate, and - more importantly - it does NOT implement its own
+enqueue. It prepares the delivery and delegates to enqueue_endpoint_command so
+the endpoint lock, the Configuration Policy gate, stale-command reaping and the
+at-most-one-in-flight rule all still apply.
+
+These tests pin that delegation. A parallel enqueue path that quietly skipped a
+lock or the in-flight rule would be invisible in normal use and would show up
+as a fleet-wide agent swap landing on a quarantined machine.
+
+The store is isolated per test: create_app('testing') resolves instance_path to
+the real repo instance/, so without redirection these would stage binaries into
+the developer's actual agent store.
+"""
+
+import os
+import tempfile
+
+import pytest
+from werkzeug.security import generate_password_hash
+
+from plugins.endpoints.api import agentstore, agentregistry, agentupgradescript
+
+UPGRADE_URL = '/api/endpoints/{}/agentupgrade'
+
+_PE_BYTES = b'MZ' + b'\x00' * 4096
+
+
+@pytest.fixture(autouse=True)
+def isolate_store(tmp_path, monkeypatch):
+    """Redirect the agent store, package output and script bodies."""
+    siteagent = tmp_path / 'siteagent'
+    packages = tmp_path / 'applicationpackages'
+    scripts = tmp_path / 'scripts'
+    for directory in (siteagent, packages, scripts):
+        directory.mkdir()
+    monkeypatch.setattr(agentstore, '_siteagent_dir', lambda: str(siteagent))
+    monkeypatch.setattr(agentregistry, 'application_package_location',
+                        lambda: (str(packages), '/api/applications/package/'))
+    monkeypatch.setattr(agentupgradescript, 'script_body_location',
+                        lambda: (str(scripts), '/api/scripts/body/'))
+    return tmp_path
+
+
+def _publish_agent(version='1.16.0.0'):
+    """Stage a build so there is something to upgrade to."""
+    agentstore.store_version('agent', version, _PE_BYTES, make_current=True)
+
+
+def _endpoint(db, hostname, agentversion='1.15.0.0'):
+    from shopdb.api import Asset, AssetType
+    from plugins.computers.models import Computer
+    from plugins.endpoints.models import EndpointState
+
+    assettype = AssetType.query.filter_by(assettype='computer').first()
+    if assettype is None:
+        assettype = AssetType(assettype='computer', pluginname='computers',
+                              tablename='computers')
+        db.session.add(assettype)
+        db.session.flush()
+
+    asset = Asset(assetnumber=hostname, name=hostname,
+                  assettypeid=assettype.assettypeid, isactive=True)
+    db.session.add(asset)
+    db.session.flush()
+    db.session.add(Computer(assetid=asset.assetid, hostname=hostname))
+    db.session.add(EndpointState(assetid=asset.assetid, hostname=hostname,
+                                 agentversion=agentversion))
+    db.session.commit()
+    return asset.assetid
+
+
+def _login(db, client, username, permissions=None, admin=False):
+    """A user holding exactly the named permissions (or the admin role)."""
+    from shopdb.core.models import User, Role, Permission
+
+    Permission.seed()
+    db.session.flush()
+
+    rolename = 'admin' if admin else username + 'role'
+    role = Role.query.filter_by(rolename=rolename).first()
+    if role is None:
+        role = Role(rolename=rolename)
+        db.session.add(role)
+        db.session.flush()
+    if not admin:
+        for name in (permissions or []):
+            perm = Permission.query.filter_by(name=name).first()
+            if perm is not None and perm not in role.permissions:
+                role.permissions.append(perm)
+    db.session.commit()
+
+    user = User(username=username, email=username + '@test.local',
+                passwordhash=generate_password_hash('testpass'))
+    user.roles.append(role)
+    db.session.add(user)
+    db.session.commit()
+
+    response = client.post('/api/auth/login',
+                           json={'username': username, 'password': 'testpass'})
+    token = response.get_json()['data']['access_token']
+    return {'Authorization': f'Bearer {token}'}
+
+
+def test_an_upgrade_queues_as_a_pinned_run_script(client, db, app):
+    """The push must ride the normal script channel, digest-pinned.
+
+    Landing as run_script is what makes the body verifiable on the endpoint;
+    a bespoke action would need its own pinning and would not get it.
+    """
+    from plugins.endpoints.models import EndpointCommand
+
+    _publish_agent()
+    assetid = _endpoint(db, 'UPGRADE01')
+    headers = _login(db, client, 'upgradeadmin', admin=True)
+
+    response = client.post(UPGRADE_URL.format(assetid), json={}, headers=headers)
+    assert response.status_code == 201
+
+    command = EndpointCommand.query.filter_by(assetid=assetid).first()
+    assert command is not None
+    assert command.action == 'run_script'
+
+    seeded = agentupgradescript.seed_upgrade_script()
+    assert command.target == 'script:{}'.format(seeded['scriptid'])
+    # Pinned to the exact body approved at enqueue, so a later edit cannot
+    # swap what the endpoint runs.
+    assert command.pinnedsha256 == seeded['sha256']
+
+
+def test_the_upgrade_requires_the_agentupdate_permission(client, db, app):
+    """endpoints.command alone must not be able to swap the SYSTEM agent."""
+    _publish_agent()
+    assetid = _endpoint(db, 'UPGRADE02')
+    headers = _login(db, client, 'plainoperator',
+                     permissions=['endpoints.view', 'endpoints.command'])
+
+    response = client.post(UPGRADE_URL.format(assetid), json={},
+                           headers=headers)
+    assert response.status_code == 403
+
+
+def test_an_upgrade_is_refused_when_no_build_is_published(client, db, app):
+    """Nothing staged means there is no payload; refuse before queueing.
+
+    Queueing anyway would send an endpoint to fetch a package that does not
+    exist and fail opaquely minutes later.
+    """
+    from plugins.endpoints.models import EndpointCommand
+
+    assetid = _endpoint(db, 'UPGRADE03')
+    headers = _login(db, client, 'nobuildadmin', admin=True)
+
+    response = client.post(UPGRADE_URL.format(assetid), json={},
+                           headers=headers)
+    assert response.status_code == 400
+    assert 'No agent build is published' in \
+        response.get_json()['data']['error']['message']
+    assert EndpointCommand.query.filter_by(assetid=assetid).count() == 0
+
+
+def test_an_endpoint_lock_still_blocks_the_upgrade(client, db, app):
+    """The delegate's lock check must not be bypassed by this route.
+
+    A quarantined machine is reserved by a person; a fleet agent swap is
+    exactly the kind of action that must respect that.
+    """
+    from plugins.endpoints.models import EndpointCommand
+
+    _publish_agent()
+    assetid = _endpoint(db, 'UPGRADE04')
+
+    # Lock as one user, then act as a different non-admin holder of the grant.
+    owner = _login(db, client, 'lockowner', admin=True)
+    locked = client.post(f'/api/endpoints/{assetid}/lock',
+                         json={'reason': 'bench repair'}, headers=owner)
+    assert locked.status_code in (200, 201)
+
+    headers = _login(db, client, 'upgradeoperator',
+                     permissions=['endpoints.view', 'endpoints.command',
+                                  'endpoints.agentupdate',
+                                  'endpoints.runscript'])
+    response = client.post(UPGRADE_URL.format(assetid), json={},
+                           headers=headers)
+
+    assert response.status_code == 403
+    assert 'locked' in \
+        response.get_json()['data']['error']['message'].lower()
+    assert EndpointCommand.query.filter_by(assetid=assetid).count() == 0
+
+
+def test_a_second_upgrade_cannot_stack_on_an_in_flight_command(client, db, app):
+    """at-most-one-in-flight must still hold through this route."""
+    from plugins.endpoints.models import EndpointCommand
+
+    _publish_agent()
+    assetid = _endpoint(db, 'UPGRADE05')
+    headers = _login(db, client, 'stackadmin', admin=True)
+
+    first = client.post(UPGRADE_URL.format(assetid), json={}, headers=headers)
+    assert first.status_code == 201
+
+    second = client.post(UPGRADE_URL.format(assetid), json={}, headers=headers)
+    assert second.status_code == 409
+    assert EndpointCommand.query.filter_by(assetid=assetid).count() == 1
+
+
+def test_the_upgrade_refreshes_the_package_before_queueing(client, db, app):
+    """A newer staged build must be what gets pushed.
+
+    If the route queued against a previously registered row, an operator who
+    uploaded a new agent and immediately pushed would ship the old one.
+    """
+    from shopdb.api import Application
+
+    _publish_agent('1.16.0.0')
+    assetid = _endpoint(db, 'UPGRADE06')
+    headers = _login(db, client, 'refreshadmin', admin=True)
+
+    client.post(UPGRADE_URL.format(assetid), json={}, headers=headers)
+    row = Application.query.filter_by(
+        appname=agentregistry.AGENT_APPNAME).first()
+    firstsha = row.installersha256
+
+    # Stage a different build and push to a second endpoint.
+    agentstore.store_version('agent', '1.17.0.0', b'MZ' + b'\x01' * 4096,
+                             make_current=True)
+    second = _endpoint(db, 'UPGRADE07')
+    response = client.post(UPGRADE_URL.format(second), json={}, headers=headers)
+    assert response.status_code == 201
+
+    db.session.expire_all()
+    row = Application.query.filter_by(
+        appname=agentregistry.AGENT_APPNAME).first()
+    assert row.installersha256 != firstsha
+
+
+def test_a_failed_push_is_not_audited_as_an_upgrade(client, db, app):
+    """A refused push must not leave an AgentUpgrade event behind."""
+    from shopdb.api import AuditLog
+
+    _publish_agent()
+    assetid = _endpoint(db, 'UPGRADE08')
+    headers = _login(db, client, 'auditadmin', admin=True)
+
+    client.post(UPGRADE_URL.format(assetid), json={}, headers=headers)
+    before = AuditLog.query.filter_by(entitytype='AgentUpgrade').count()
+
+    # Second push is refused by the in-flight rule.
+    blocked = client.post(UPGRADE_URL.format(assetid), json={}, headers=headers)
+    assert blocked.status_code == 409
+
+    after = AuditLog.query.filter_by(entitytype='AgentUpgrade').count()
+    assert after == before
+
+
+def test_the_seeded_script_body_is_written_and_pinned(client, db, app,
+                                                      isolate_store):
+    """The agent verifies the body by digest, so both must exist and agree."""
+    import hashlib
+
+    _publish_agent()
+    assetid = _endpoint(db, 'UPGRADE09')
+    headers = _login(db, client, 'bodyadmin', admin=True)
+
+    response = client.post(UPGRADE_URL.format(assetid), json={},
+                           headers=headers)
+    assert response.status_code == 201
+
+    seeded = agentupgradescript.seed_upgrade_script()
+    path = os.path.join(str(isolate_store / 'scripts'),
+                        'script-{}.ps1'.format(seeded['scriptid']))
+    assert os.path.isfile(path)
+    with open(path, 'rb') as handle:
+        body = handle.read()
+    assert hashlib.sha256(body).hexdigest() == seeded['sha256']
+    # The delivery path must be fully resolved, not a literal placeholder.
+    assert b'{{AGENT_APPID}}' not in body