fix(studio-bridge): fix coroutine resume race and skip play-mode contexts

Use task.defer instead of task.spawn to resume the caller thread in
scanPortsAsync, preventing "cannot resume non-suspended coroutine"
errors. Skip plugin initialization in client/server play-mode contexts
since HttpService is restricted to the game server.

Increase session settle timeout from 2.5s to 4s to allow more time for
persistent plugins to discover the ephemeral host.

Author: Quenty

tools/studio-bridge/src/bridge/bridge-connection.ts

@@ -451,18 +451,18 @@ export class BridgeConnection extends EventEmitter {
   async waitForSessionsToSettleAsync(options?: {
     /** Max time to wait for the first session (ms). Default: 5000 */
     firstSessionTimeout?: number;
-    /** How long to wait after the last connection before considering settled (ms). Default: 2500 */
+    /** How long to wait after the last connection before considering settled (ms). Default: 4000 */
     settleMs?: number;
-    /** Absolute max wait time (ms). Default: 10000 */
+    /** Absolute max wait time (ms). Default: 15000 */
     maxMs?: number;
   }): Promise<void> {
     if (this._role !== 'host') {
       return;
     }
 
     const firstTimeout = options?.firstSessionTimeout ?? 5_000;
-    const settleMs = options?.settleMs ?? 2_500;
-    const maxMs = options?.maxMs ?? 10_000;
+    const settleMs = options?.settleMs ?? 4_000;
+    const maxMs = options?.maxMs ?? 15_000;
 
     // Wait for the first session
     try {

tools/studio-bridge/templates/studio-bridge-plugin/src/StudioBridgePlugin.server.lua

@@ -33,8 +33,10 @@ local PORT = "{{PORT}}"
 local SESSION_ID = "{{SESSION_ID}}"
 local IS_EPHEMERAL = ("{{EPHEMERAL}}" == "true")
 
--- Only run inside Studio
-if not RunService:IsStudio() then
+-- Only run inside Studio edit context. Plugin instances spawned by play
+-- mode (client/server) cannot make HTTP requests, so they cannot discover
+-- the bridge. The edit-context instance stays alive during play mode.
+if not RunService:IsStudio() or RunService:IsRunning() then
 	return
 end
 
@@ -254,7 +256,8 @@ else
 		scanPortsAsync = function(ports, timeoutSec)
 			-- Scan all ports in parallel using task.spawn. The calling thread
 			-- yields and is resumed as soon as any port succeeds, all fail,
-			-- or the timeout expires.
+			-- or the timeout expires. Use task.defer (not task.spawn) to resume
+			-- the caller so it has time to reach coroutine.yield() first.
 			local callerThread = coroutine.running()
 			local foundPort = nil
 			local foundBody = nil
@@ -270,13 +273,13 @@ else
 						foundPort = port
 						foundBody = body
 						settled = true
-						task.spawn(callerThread)
+						task.defer(callerThread)
 						return
 					end
 					remaining -= 1
 					if remaining <= 0 and not settled then
 						settled = true
-						task.spawn(callerThread)
+						task.defer(callerThread)
 					end
 				end)
 				table.insert(threads, thread)
@@ -286,13 +289,11 @@ else
 			local timeoutThread = task.delay(timeoutSec, function()
 				if not settled then
 					settled = true
-					task.spawn(callerThread)
+					task.defer(callerThread)
 				end
 			end)
 
-			if not settled then
-				coroutine.yield()
-			end
+			coroutine.yield()
 
 			-- Cancel remaining HTTP threads and the timeout
 			pcall(task.cancel, timeoutThread)