Fix port conflicts for concurrent sessions by dynamically assigning ports

[GeorgeNgMsft]

Goal
Eliminate port conflicts when multiple TypeAgent sessions start concurrently by switching from pre-assigned static ports to OS-assigned dynamic ports. Agents now bind on port 0 and report their actual bound port back to the dispatcher via IPC.

Also cleanup server startup/exit for browser & montage agents.

Summary

• Agents with localView now bind to port 0 (OS-assigned) instead of a fixed base port
• The view server process sends { type:"Success", port: } over IPC after starting, and the dispatcher stores the actual port via the new setLocalHostPort() API
• Added closeAgentContext to browserActionHandler for proper process cleanup on shutdown
• Fixed montage and markdown agent view process cleanup in closeAgentContext
• Improved error handling: EADDRINUSE and other server startup errors are now surfaced clearly rather than silently failing
• Removed portBase option and the nextPortIndex counter from AppAgentManager — no longer needed

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Improves agent shutdown/startup robustness to reduce port-collision (EADDRINUSE) failures and to better clean up spawned processes/servers.

Changes:

• Add explicit EADDRINUSE handling when starting the Montage route server and the Browser agent’s BaseServer.
• Ensure Montage view process is terminated during context close.
• Add closeAgentContext to the Browser agent to stop the websocket server and kill spawned processes.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
ts/packages/agents/montage/src/route/route.ts	Wraps listen() to capture and report EADDRINUSE / server start failures
ts/packages/agents/montage/src/agent/montageActionHandler.ts	Kills viewProcess on context close to avoid leakage
ts/packages/agents/browser/src/views/server/core/baseServer.ts	Rejects start() on port-in-use instead of silently hanging/never resolving
ts/packages/agents/browser/src/agent/browserActionHandler.mts	Adds closeAgentContext to stop websocket server and kill spawned processes

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[Copilot]

Pull request overview

Copilot reviewed 21 out of 21 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

ts/packages/dispatcher/dispatcher/src/context/appAgentManager.ts:529

• manifest.localView agents now store record.port = 0, which is treated as a real port elsewhere (e.g. activity handling opens http://localhost:0/ when openLocalView is requested). Consider keeping record.port as undefined until the view server reports its actual bound port via setLocalHostPort(), and separately pass 0 only as the requested listen port when initializing/spawning the view server.

        const port = manifest.localView ? 0 : undefined;

        if (port !== undefined) {
            debug(`Dynamic port (OS-assigned) reserved for ${appAgentName}`);
        }

        const record: AppAgentRecord = {
            name: appAgentName,
            provider,
            actions: new Set(),
            schemas: new Set(),
            schemaErrors,
            commands: false,
            manifest,
            port,
        };

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