Have Task choose free ports for dev servers (#6145)

.taskfiles/backend.yml

@@ -4,10 +4,15 @@ tasks:
   dev:
     desc: "Start backend dev server"
     ignore_error: true
+    vars:
+      PORT: '{{.PORT | default "8080"}}'
+      AIENGINE_URL: '{{.AIENGINE_URL | default ""}}'
+    env:
+      SERVER_PORT: '{{.PORT}}'
     cmds:
-      - cmd: cmd /c gradlew.bat :stirling-pdf:bootRun
+      - cmd: '{{if .AIENGINE_URL}}set "AIENGINE_URL={{.AIENGINE_URL}}" && set "AIENGINE_ENABLED=true" && {{end}}cmd /c gradlew.bat :stirling-pdf:bootRun'
         platforms: [windows]
-      - cmd: ./gradlew :stirling-pdf:bootRun
+      - cmd: '{{if .AIENGINE_URL}}AIENGINE_URL={{.AIENGINE_URL}} AIENGINE_ENABLED=true {{end}}./gradlew :stirling-pdf:bootRun'
         platforms: [linux, darwin]
 
   build:

.taskfiles/desktop.yml

@@ -6,7 +6,11 @@ vars:
 tasks:
   prepare:
     desc: "Prepare desktop build dependencies"
-    deps: [jlink, ":frontend:prepare:desktop", provisioner]
+    deps:
+      - jlink
+      - task: ":frontend:prepare"
+        vars: { MODE: desktop }
+      - provisioner
 
   provisioner:
     desc: "Build installer provisioner"

.taskfiles/engine.yml

@@ -28,20 +28,24 @@ tasks:
     deps: [prepare]
     ignore_error: true
     dir: src
+    vars:
+      PORT: '{{.PORT | default "5001"}}'
     env:
       PYTHONUNBUFFERED: "1"
     cmds:
-      - uv run uvicorn stirling.api.app:app --host 0.0.0.0 --port 5001
+      - uv run uvicorn stirling.api.app:app --host 0.0.0.0 --port {{.PORT}}
 
   dev:
     desc: "Start engine dev server with hot reload"
     deps: [prepare]
     ignore_error: true
     dir: src
+    vars:
+      PORT: '{{.PORT | default "5001"}}'
     env:
       PYTHONUNBUFFERED: "1"
     cmds:
-      - uv run uvicorn stirling.api.app:app --host 0.0.0.0 --port 5001 --reload
+      - uv run uvicorn stirling.api.app:app --host 0.0.0.0 --port {{.PORT}} --reload
 
   lint:
     desc: "Run linting"

.taskfiles/frontend.yml

@@ -15,42 +15,21 @@ tasks:
       CI: '{{ .CI | default "false" }}'
 
   prepare:env:
-    desc: "Generate .env from example if missing"
+    internal: true
-    run: once
+    run: when_changed
     deps: [install]
+    vars:
+      MODE: '{{.MODE | default ""}}'
     cmds:
-      - npx tsx scripts/setup-env.ts
+      - npx tsx scripts/setup-env.ts{{if .MODE}} --{{.MODE}}{{end}}
     sources:
       - scripts/setup-env.ts
     generates:
       - .env.local
-
+      - .env{{if .MODE}}.{{.MODE}}{{end}}.local
-  prepare:env:saas:
-    desc: "Generate .env and .env.saas from examples if missing"
-    run: once
-    deps: [install]
-    cmds:
-      - npx tsx scripts/setup-env.ts --saas
-    sources:
-      - scripts/setup-env.ts
-    generates:
-      - .env.local
-      - .env.saas.local
-
-  prepare:env:desktop:
-    desc: "Generate .env and .env.desktop from examples if missing"
-    run: once
-    deps: [install]
-    cmds:
-      - npx tsx scripts/setup-env.ts --desktop
-    sources:
-      - scripts/setup-env.ts
-    generates:
-      - .env.local
-      - .env.desktop.local
 
   prepare:icons:
-    desc: "Generate icon bundle from source references"
+    internal: true
     run: once
     deps: [install]
     cmds:
@@ -58,64 +37,75 @@ tasks:
 
   prepare:
     desc: "Set up dev environment"
-    run: once
+    run: when_changed
-    deps: [prepare:env, prepare:icons]
+    vars:
-
+      MODE: '{{.MODE | default ""}}'
-  prepare:saas:
+    deps:
-    desc: "Prepare for SaaS mode"
+      - task: prepare:env
-    run: once
+        vars: { MODE: '{{.MODE}}' }
-    deps: [prepare:env:saas, prepare:icons]
+      - prepare:icons
-
-  prepare:desktop:
-    desc: "Prepare for desktop mode"
-    run: once
-    deps: [prepare:env:desktop, prepare:icons]
 
   # ============================================================
   # Development
   # ============================================================
 
+  dev:_run:
+    internal: true
+    ignore_error: true
+    vars:
+      MODE: '{{.MODE}}'
+      PORT: '{{.PORT | default "5173"}}'
+      BACKEND_URL: '{{.BACKEND_URL | default "http://localhost:8080"}}'
+      OPEN: '{{.OPEN | default ""}}'
+    env:
+      BACKEND_URL: '{{.BACKEND_URL}}'
+    cmds:
+      - npx vite --mode {{.MODE}} --port {{.PORT}}{{if .OPEN}} --open{{end}}
+
   dev:
     desc: "Start frontend dev server"
-    deps: [prepare]
-    ignore_error: true
     cmds:
-      - npx vite
+      - task: dev:proprietary
+        vars: { PORT: '{{.PORT}}', BACKEND_URL: '{{.BACKEND_URL}}', OPEN: '{{.OPEN}}' }
 
   dev:core:
     desc: "Start frontend dev server in core mode"
     deps: [prepare]
-    ignore_error: true
     cmds:
-      - npx vite --mode core
+      - task: dev:_run
+        vars: { MODE: core, PORT: '{{.PORT}}', BACKEND_URL: '{{.BACKEND_URL}}', OPEN: '{{.OPEN}}' }
 
   dev:proprietary:
     desc: "Start frontend dev server in proprietary mode"
     deps: [prepare]
-    ignore_error: true
     cmds:
-      - npx vite --mode proprietary
+      - task: dev:_run
+        vars: { MODE: proprietary, PORT: '{{.PORT}}', BACKEND_URL: '{{.BACKEND_URL}}', OPEN: '{{.OPEN}}' }
 
   dev:saas:
     desc: "Start frontend dev server in SaaS mode"
-    deps: [prepare:saas]
+    deps:
-    ignore_error: true
+      - task: prepare
+        vars: { MODE: saas }
     cmds:
-      - npx vite --mode saas
+      - task: dev:_run
+        vars: { MODE: saas, PORT: '{{.PORT}}', BACKEND_URL: '{{.BACKEND_URL}}', OPEN: '{{.OPEN}}' }
 
   dev:desktop:
     desc: "Start frontend dev server in desktop mode"
-    deps: [prepare:desktop]
+    deps:
-    ignore_error: true
+      - task: prepare
+        vars: { MODE: desktop }
     cmds:
-      - npx vite --mode desktop
+      - task: dev:_run
+        vars: { MODE: desktop, PORT: '{{.PORT}}', BACKEND_URL: '{{.BACKEND_URL}}', OPEN: '{{.OPEN}}' }
 
   dev:prototypes:
     desc: "Start frontend dev server in prototypes mode"
     deps: [prepare]
-    ignore_error: true
     cmds:
-      - npx vite --mode prototypes
+      - task: dev:_run
+        vars: { MODE: prototypes, PORT: '{{.PORT}}', BACKEND_URL: '{{.BACKEND_URL}}', OPEN: '{{.OPEN}}' }
 
   # ============================================================
   # Build
@@ -141,13 +131,17 @@ tasks:
 
   build:saas:
     desc: "Build for SaaS mode"
-    deps: [prepare:saas]
+    deps:
+      - task: prepare
+        vars: { MODE: saas }
     cmds:
       - npx vite build --mode saas
 
   build:desktop:
     desc: "Build for desktop mode"
-    deps: [prepare:desktop]
+    deps:
+      - task: prepare
+        vars: { MODE: desktop }
     cmds:
       - npx vite build --mode desktop
 
@@ -211,13 +205,17 @@ tasks:
 
   typecheck:saas:
     desc: "Typecheck SaaS build variant"
-    deps: [prepare:saas]
+    deps:
+      - task: prepare
+        vars: { MODE: saas }
     cmds:
       - npx tsc --noEmit --project src/saas/tsconfig.json
 
   typecheck:desktop:
     desc: "Typecheck desktop build variant"
-    deps: [prepare:desktop]
+    deps:
+      - task: prepare
+        vars: { MODE: desktop }
     cmds:
       - npx tsc --noEmit --project src/desktop/tsconfig.json
 

AGENTS.md

@@ -6,6 +6,8 @@ This file provides guidance to AI Agents when working with code in this reposito
 
 This project uses [Task](https://taskfile.dev/) as a unified command runner. All build, dev, test, lint, and docker commands can be run from the repo root via `task <command>`. Run `task --list` to see all available commands.
 
+Task `desc:` fields should describe **what** the task does, not **how** it does it. Keep them generic and stable: don't reference implementation details like aliases, internal helpers, mode flags, or which other task delegates to which. The description is for users picking a command from `task --list`, not a changelog of refactors.
+
 ### Quick Reference
 - `task install` — install all dependencies
 - `task dev` — start backend + frontend concurrently
@@ -143,7 +145,7 @@ The project structure is defined in `engine/pyproject.toml`. Any new dependencie
 - These files are committed to Git and must not contain private keys
 - Local overrides (API keys, machine-specific settings) go in uncommitted sibling `.env.local` / `.env.saas.local` / `.env.desktop.local` files — Vite automatically layers them on top
 - Never use `|| 'hardcoded-fallback'` inline — put defaults in the committed env files
-- `task frontend:prepare` / `prepare:saas` / `prepare:desktop` create empty `.local` override files on first run
+- `task frontend:prepare` creates empty `.local` override files on first run; pass `MODE=saas` or `MODE=desktop` to also create the mode-specific `.local` file
 - Prepare runs automatically as a dependency of all `dev*`, `build*`, and `desktop*` tasks
 - See `frontend/README.md#environment-variables` for full documentation
 

Taskfile.yml

@@ -2,6 +2,10 @@ version: '3'
 
 output: prefixed
 
+vars:
+  FIND_FREE_PORT_PS: powershell -NoProfile -File scripts\find-free-port.ps1 -Preferred
+  FIND_FREE_PORT_SH: bash scripts/find-free-port.sh
+
 includes:
   backend:
     taskfile: .taskfiles/backend.yml
@@ -35,17 +39,43 @@ tasks:
   # ============================================================
 
   dev:
-    desc: "Start backend + frontend concurrently"
+    desc: "Start backend + frontend concurrently on free ports"
+    vars:
+      PORTS:
+        sh: '{{if eq OS "windows"}}{{.FIND_FREE_PORT_PS}} 8080,5173{{else}}{{.FIND_FREE_PORT_SH}} 8080 5173{{end}}'
+      BACKEND_PORT: '{{index (splitList "\n" .PORTS) 0}}'
+      FRONTEND_PORT: '{{index (splitList "\n" .PORTS) 1}}'
     deps:
-      - backend:dev
+      - task: backend:dev
-      - frontend:dev
+        vars:
+          PORT: '{{.BACKEND_PORT}}'
+      - task: frontend:dev
+        vars:
+          PORT: '{{.FRONTEND_PORT}}'
+          BACKEND_URL: 'http://localhost:{{.BACKEND_PORT}}'
+          OPEN: "true"
 
   dev:all:
-    desc: "Start backend + frontend + engine concurrently"
+    desc: "Start backend + frontend + engine concurrently on free ports"
+    vars:
+      PORTS:
+        sh: '{{if eq OS "windows"}}{{.FIND_FREE_PORT_PS}} 8080,5173,5001{{else}}{{.FIND_FREE_PORT_SH}} 8080 5173 5001{{end}}'
+      BACKEND_PORT: '{{index (splitList "\n" .PORTS) 0}}'
+      FRONTEND_PORT: '{{index (splitList "\n" .PORTS) 1}}'
+      ENGINE_PORT: '{{index (splitList "\n" .PORTS) 2}}'
     deps:
-      - backend:dev
+      - task: engine:dev
-      - frontend:dev:prototypes
+        vars:
-      - engine:dev
+          PORT: '{{.ENGINE_PORT}}'
+      - task: backend:dev
+        vars:
+          PORT: '{{.BACKEND_PORT}}'
+          AIENGINE_URL: 'http://localhost:{{.ENGINE_PORT}}'
+      - task: frontend:dev:prototypes
+        vars:
+          PORT: '{{.FRONTEND_PORT}}'
+          BACKEND_URL: 'http://localhost:{{.BACKEND_PORT}}'
+          OPEN: "true"
 
   # ============================================================
   # Build

frontend/vite.config.ts

@@ -39,6 +39,16 @@ export default defineConfig(({ mode }) => {
 
   const tsconfigProject = TSCONFIG_MAP[effectiveMode];
 
+  // Backend proxy target: default localhost:8080. Override via BACKEND_URL env var
+  // so the top-level dev launcher can wire a dynamically-assigned backend port.
+  const backendUrl = process.env.BACKEND_URL || "http://localhost:8080";
+  const backendProxy = {
+    target: backendUrl,
+    changeOrigin: true,
+    secure: false,
+    xfwd: true,
+  };
+
   return {
     plugins: [
       react(),
@@ -88,48 +98,13 @@ export default defineConfig(({ mode }) => {
         effectiveMode === "desktop"
           ? undefined
           : {
-              "/api": {
+              "/api": backendProxy,
-                target: "http://localhost:8080",
+              "/oauth2": backendProxy,
-                changeOrigin: true,
+              "/saml2": backendProxy,
-                secure: false,
+              "/login/oauth2": backendProxy,
-                xfwd: true,
+              "/login/saml2": backendProxy,
-              },
+              "/swagger-ui": backendProxy,
-              "/oauth2": {
+              "/v1/api-docs": backendProxy,
-                target: "http://localhost:8080",
-                changeOrigin: true,
-                secure: false,
-                xfwd: true,
-              },
-              "/saml2": {
-                target: "http://localhost:8080",
-                changeOrigin: true,
-                secure: false,
-                xfwd: true,
-              },
-              "/login/oauth2": {
-                target: "http://localhost:8080",
-                changeOrigin: true,
-                secure: false,
-                xfwd: true,
-              },
-              "/login/saml2": {
-                target: "http://localhost:8080",
-                changeOrigin: true,
-                secure: false,
-                xfwd: true,
-              },
-              "/swagger-ui": {
-                target: "http://localhost:8080",
-                changeOrigin: true,
-                secure: false,
-                xfwd: true,
-              },
-              "/v1/api-docs": {
-                target: "http://localhost:8080",
-                changeOrigin: true,
-                secure: false,
-                xfwd: true,
-              },
             },
     },
     base: env.RUN_SUBPATH ? `/${env.RUN_SUBPATH}` : "./",

scripts/find-free-port.ps1

@@ -0,0 +1,41 @@
+# Prints one free TCP port per preferred port given as an argument.
+#
+# For each element of -Preferred, emits that port if it's free; otherwise
+# emits a random free port in 20000-49999. Probes by attempting to bind a
+# TcpListener on loopback. Tracks picks within this run so outputs are
+# guaranteed distinct from each other.
+param([int[]]$Preferred)
+
+$script:picked = @()
+
+function Test-PortFree {
+    param([int]$Port)
+    if ($script:picked -contains $Port) { return $false }
+    try {
+        $listener = [System.Net.Sockets.TcpListener]::new([System.Net.IPAddress]::Loopback, $Port)
+        $listener.Start()
+        $listener.Stop()
+        return $true
+    } catch {
+        return $false
+    }
+}
+
+function Get-RandomFreePort {
+    while ($true) {
+        $port = Get-Random -Minimum 20000 -Maximum 50000
+        if (Test-PortFree $port) { return $port }
+    }
+}
+
+foreach ($p in $Preferred) {
+    if (Test-PortFree $p) {
+        $script:picked += $p
+    } else {
+        $script:picked += Get-RandomFreePort
+    }
+}
+
+foreach ($p in $script:picked) {
+    [Console]::Out.Write("$p`n")
+}

scripts/find-free-port.sh

@@ -0,0 +1,43 @@
+#!/usr/bin/env bash
+# Prints one free TCP port per preferred port given as an argument.
+#
+# For each argument, emits that port if it's free; otherwise emits a random
+# free port in 20000-49999. Probes via bash's /dev/tcp pseudo-device (connect
+# failure = nobody listening). Tracks picks within this run so outputs are
+# guaranteed distinct from each other.
+set -euo pipefail
+
+declare -a picked=()
+
+is_free() {
+  local port=$1
+  for p in ${picked[@]+"${picked[@]}"}; do
+    if [ "$p" = "$port" ]; then return 1; fi
+  done
+  if (exec 3<>"/dev/tcp/127.0.0.1/$port") >/dev/null 2>&1; then
+    return 1
+  fi
+  return 0
+}
+
+random_free_port() {
+  while true; do
+    local port=$((RANDOM % 30000 + 20000))
+    if is_free "$port"; then
+      echo "$port"
+      return
+    fi
+  done
+}
+
+for preferred in "$@"; do
+  if is_free "$preferred"; then
+    picked+=("$preferred")
+  else
+    picked+=("$(random_free_port)")
+  fi
+done
+
+for p in "${picked[@]}"; do
+  echo "$p"
+done