Port Registrar: Local-view port registration + Origin gate

[TalZaccai]

Why

Two gaps motivated the change:

1. Role collision in the browser agent. The WS bridge already registers (browser, "default"); the views server's setLocalHostPort registered another entry under the same (agent, role) slot, so whichever ran second overwrote the other. @system ports and discoverPort("browser") could return either depending on init order.
2. No Origin gate on the three view listeners. All three bind on loopback, but loopback bind alone doesn't stop a malicious local web page from hitting http://localhost:<port> via fetch/XHR/iframe. The PDF viewer, image-gallery folder paths, and markdown live document + Yjs WS were all readable cross-origin to anything running on the same host.

What

• New originAllowlist.ts per package (browser-views, montage, markdown): loopback-only HTTP(S); absent/null/empty Origin allowed for same-origin fetch and Node ws clients. Markdown's Yjs WebSocket upgrade reuses the same allowlist.
• Each agent's view-handler now calls context.registerPort("view", port) after the child reports its bound port, stores the release handle on agentContext.viewPortRegistration, and releases it in the disable + close paths. setLocalHostPort calls are removed.
• Context types (BrowserActionContext, MontageActionContext, MarkdownActionContext) gain a viewPortRegistration?: { release: () => void } field.
• Dispatcher: appAgentManager.getLocalHostPort and getSharedLocalHostPort fall back to role "view" after "default" so cross-agent site lookup (browserActionHandler.mts:1335) keeps working through the migration. A new LOCAL_VIEW_ROLE constant documents the alias.

Validation

• pnpm --filter browser-typeagent --filter montage-agent --filter markdown-agent --filter agent-dispatcher build — clean.
• pnpm --filter ... prettier — clean.
• pnpm --filter agent-dispatcher test — 671 tests pass (covers portRegistrar.spec.js, appAgentManager-adjacent suites).
• Manual smoke tests: see pr-phase-a-manual-tests.md.

Reading order

1. dispatcher/dispatcher/src/context/appAgentManager.ts — fallback lookup + LOCAL_VIEW_ROLE constant.
2. agents/browser/src/views/server/core/baseServer.ts + new originAllowlist.ts — Origin middleware pattern.
3. agents/browser/src/agent/browserActionHandler.mts — registerPort("view", ...) + release plumbing (template for the other two).
4. agents/montage/src/route/route.ts + handler.
5. agents/markdown/src/view/route/service.ts + handler — note the WS upgrade gate alongside the HTTP middleware.

[Copilot]

Pull request overview

This PR updates how per-session “view” servers (browser views/PDF viewer, montage gallery, markdown preview + Yjs) register their loopback ports to avoid (agent, role) collisions, and adds Origin-based gating to reduce localhost cross-origin exposure.

Changes:

• Migrates view servers from setLocalHostPort to explicit sessionContext.registerPort("view", port) with release plumbing in agents.
• Adds LOCAL_VIEW_ROLE fallback lookup in the dispatcher so callers that still assume "default" continue to work during migration.
• Introduces per-package Origin allowlists and middleware/upgrade checks for the browser views, montage, and markdown view servers.

Reviewed changes

Copilot reviewed 13 out of 14 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
ts/pnpm-lock.yaml	Updates lockfile for new workspace deps and updated dependency graph.
ts/packages/dispatcher/dispatcher/src/context/appAgentManager.ts	Adds "view" role fallback for local port lookups and documents the migration via LOCAL_VIEW_ROLE.
ts/packages/agents/montage/src/route/route.ts	Adds early Origin-gating middleware for the montage HTTP server.
ts/packages/agents/montage/src/route/originAllowlist.ts	Adds shared allowlist wrapper for montage view server Origin checks.
ts/packages/agents/montage/src/agent/montageActionHandler.ts	Registers montage view server port under role "view" and releases it on disable/close.
ts/packages/agents/montage/package.json	Adds websocket-utils dependency for shared Origin allowlist.
ts/packages/agents/markdown/src/view/route/service.ts	Adds Origin gate middleware and WS-upgrade gating for the markdown preview/Yjs server.
ts/packages/agents/markdown/src/view/route/originAllowlist.ts	Adds shared allowlist wrapper for markdown view server Origin checks.
ts/packages/agents/markdown/src/agent/markdownActionHandler.ts	Registers markdown view server port under role "view" and releases it on disable.
ts/packages/agents/markdown/package.json	Adds websocket-utils dependency for shared Origin allowlist.
ts/packages/agents/browser/src/views/server/core/originAllowlist.ts	Adds shared allowlist wrapper for browser views server Origin checks.
ts/packages/agents/browser/src/views/server/core/baseServer.ts	Adds early Origin-gating middleware for browser views server.
ts/packages/agents/browser/src/agent/browserActions.mts	Extends browser action context type to track view port registration handle.
ts/packages/agents/browser/src/agent/browserActionHandler.mts	Registers browser views server port under role "view" and releases it on disable/close.

Files not reviewed (1)

• ts/pnpm-lock.yaml: Language not supported

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