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pt_live_deploy is the real-time deployment path. It converts a TopologyPlan into executable JavaScript commands — device placements, module installs, cable connections, IOS configurations, and PC IP assignments — and streams each command to a running Cisco Packet Tracer instance through the HTTP bridge at http://127.0.0.1:54321. PTBuilder’s webview polls the bridge every 500 ms and executes each command in Packet Tracer’s Script Engine via $se('runCode', ...). The result is a fully built and configured topology appearing directly in Packet Tracer with no manual copy-pasting.

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Parameters

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plan_json
string
required
The TopologyPlan JSON produced by pt_plan_topology or pt_full_build. Must contain at least one device.
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command_delay
number
default:"1.0"
Delay in seconds between consecutive commands sent to the bridge. Values below 1.0 are automatically clamped to 1.0. A delay shorter than one second may cause configureIosDevice or configurePcIp to run before a device finishes initializing, which triggers error popups in Packet Tracer and can kill the bootstrap polling loop.

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Return value

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result
string
A summary string reporting how many commands were sent and how many devices and links were deployed. Example: "Topologia desplegada en Packet Tracer!\n Comandos enviados: 21\n Dispositivos: 8\n Enlaces: 7".

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Prerequisites

Before calling pt_live_deploy, the HTTP bridge must be active and PTBuilder must be polling it. The MCP server starts the bridge automatically as an in-process daemon thread when it registers tools — you do not need to run start_bridge.ps1 or any external process. You only need to paste the bootstrap snippet once per Packet Tracer session. Bootstrap snippet (paste into Extensions → Builder Code Editor, then click Run): 
/* PT-MCP Bridge */ window.webview.evaluateJavaScriptAsync("setInterval(function(){var x=new XMLHttpRequest();x.open('GET','http://127.0.0.1:54321/next',true);x.onload=function(){if(x.status===200&&x.responseText){$se('runCode',x.responseText)}};x.onerror=function(){};x.send()},500)");
This injects a setInterval into the PTBuilder webview (a Chromium QWebEngine context that has full XMLHttpRequest support). Every 500 ms the webview fetches /next from the bridge; when a command is queued, it calls $se('runCode', cmd) to execute it in Packet Tracer’s Script Engine.
The bridge starts automatically, but PTBuilder must have the bootstrap running before you call pt_live_deploy. If the bridge is up but PT is not connected, the tool returns the bootstrap snippet with instructions rather than deploying. Call pt_bridge_status first to confirm the connection is ready.

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What happens during deployment

The executor breaks the full topology script into individual lines and sends them one at a time to POST /queue on the bridge. PTBuilder picks each command up on its next 500 ms poll and runs it in the Script Engine. The sequence is:
  1. Runtime patches are injected first (idempotent, once per PT session) — these override addModule, configureIosDevice, configurePcIp, and lwAddDevice/lwAddLink with defensive versions that prevent crashes on host devices
  2. lwAddDevice calls place each device on the logical canvas
  3. addModule calls install expansion modules (e.g. HWIC-2T for serial ports)
  4. lwAddLink calls draw cables between interfaces
  5. configureIosDevice calls push the full IOS CLI config to each router and switch
  6. configurePcIp calls set static IPs or enable DHCP on PC-PT, Laptop-PT, and Server-PT devices
Each command is separated by command_delay seconds to give Packet Tracer time to finish processing before the next command arrives.

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Bridge architecture

MCP Server (:39000)
    │  POST /queue  (one JS command at a time)
    ▼
HTTP Bridge (:54321)
    │  GET /next every 500 ms
    ▼
PTBuilder WebView (Chromium / QWebEngine)
    │  $se('runCode', cmd)
    ▼
Packet Tracer Script Engine
    │  executes lwAddDevice, lwAddLink, configureIosDevice, ...
    ▼
Packet Tracer Canvas

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Troubleshooting

SymptomLikely causeFix
”Bridge activo pero PT NO está conectado”Bootstrap not pasted or PT was restartedPaste bootstrap in Extensions → Builder Code Editor → Run
Devices appear but configs not appliedcommand_delay too lowIncrease to 2.0 or higher
Nothing appears in PTBridge not respondingCheck pt_bridge_status — bridge auto-starts but verify it’s running
Error popups in PTconfigureIosDevice ran before device bootedIncrease command_delay
For full bridge setup instructions, see Live Deploy Setup.
For topologies with many devices or slow hardware, set command_delay to 2.0 to give Packet Tracer extra time to initialize each device before the next command arrives.

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