This Week in Extensibility: Meta opens its personal agent to third-party developers, Google turns on end-user automation building in Workspace, and Adobe sets a deadline to retire its old Creative Cloud plugin system

2026-09-25T00:00:00-04:00

Meta opened its new personal agent to outside developers this week, turning Muse into a platform that third parties build connectors for. Google, separately, put automation building in the hands of ordinary Workspace users. On the controls around a customer's own agent, the Model Context Protocol added per-tool consent, Cloudflare shipped an administrator's gateway that decides which tools that agent is allowed to reach, and the draft WebMCP standard drew formal privacy objections. Adobe and Atlassian each set a retirement deadline for an old extension system, one in Creative Cloud and the other in Jira dashboards, and Roblox widened where its creators can sell what they make.

Agents: Meta opens its personal agent to third-party developers

Meta opened a connector platform that lets outside developers plug their own services into Muse, its new personal AI agent. At Meta Connect on September 23, the company laid out how the Muse Connector Platform works. A developer submits their product, Meta reviews it for functional, security, and legal requirements and runs it through end-to-end testing, and once approved it appears in a directory a person can pull into the agent by asking for it in plain language. Meta said it received more than 1,500 developer applications in under a week. The first connectors cover shopping and everyday tools, among them Shopify, Walmart, Best Buy, Instacart, Gmail, and GitHub, and days earlier Shopify agreed to let Muse check out across its stores through Shop Pay.

Why it matters: it puts an app store on top of a personal agent, so the unit a business ships to reach a user becomes a connector that user's agent can call rather than an app someone opens. Meta, not the user, decides which services clear review and surface in the directory, which makes the connector platform the control point for what people can automate through the agent Meta puts in front of them.

Automation: Google lets Workspace users build their own automations

Google switched on end-user automation building inside Workspace Studio. Starting September 21 for its faster-updating customers, its embedded automation builder now lets a person set up their own real-time triggers, run custom logic, move data to and from outside services like Asana, HubSpot, Jira, and Salesforce, and push information out to other systems on their own schedule. The outbound connections are limited to higher-tier plans and sit behind an administrator's list of approved addresses.

Why it matters: it moves the person who builds an automation from a developer to anyone with a Workspace account, across a very large base of paid users. Triggering on live events and pushing data out to other systems used to require an integration developer.

Standards: WebMCP draws privacy objections over handing tools to an agent

The draft WebMCP standard drew four formal privacy and security objections. WebMCP is the browser proposal that lets any website register tools a person's AI agent can call. The lead objection, a tracked filing from the Center for Democracy & Technology that can hold up the standard's progress, warns that a malicious site could reach personal data across other sites and act without the person noticing. The others warn that invisible tools let a page expose actions it never shows the user, that the design turns sensitive fields like card security codes and one-time passcodes into agent-fillable inputs, and that a hosting requirement keeps the standard off non-Google browsers. They arrived ahead of real adoption. A crawl the same week found around 580 sites registering these tools, most of them from a few plugins. WebMCP is a Chrome origin trial, an experiment a site opts into, not a default browser feature.

The editors have started to respond, treating whether a tool is surfaced as a decision for the agent rather than the browser and moving to drop the hosting requirement that blocked non-Google browsers, though the core privacy objection stays open. A parallel proposal in an early web-incubation group would seal a form field's value so neither a page script nor an agent can read it before it reaches its destination, a direct answer to the worry about sensitive inputs.

Why it matters: WebMCP is the layer that decides whether an arbitrary website can hand agent-actionable tools to a person's own agent. The privacy questions now sit formally in the standard's path rather than to the side of it.

Infrastructure: MCP and Cloudflare tighten what an agent can reach

The Model Context Protocol added per-tool consent to its most-used server toolkit. An MCP server can now require a specific permission for each individual tool at the moment an agent calls it, refusing the call until the person grants that narrower permission. Because a growing number of products use the Model Context Protocol to let a person's agent act on their behalf, per-tool consent is what lets a product safely expose an action that writes or changes data, rather than granting an agent everything at once.

Separately, Cloudflare brought its agent-access control point to general availability. Its control point for the tools a person's agent may reach went live for all customers on September 24, giving a person one approved endpoint for the servers their agent can use, and days earlier it gained the ability to front tools on an internal network without exposing them to the public internet. The Model Context Protocol project also chartered new working groups under its governance, including one that packages reusable agent skills so they can be shared across tools.

Why it matters: both moves are about the controls around an agent, not the agent itself. Per-tool consent and an administrator-controlled catalog of reachable servers are the controls that decide how far a customer can safely let their own agent act inside the software they use.

Platforms: Adobe and Atlassian put clocks on their old plugin systems

Adobe set a multi-year timeline to retire the extension system its Creative Cloud plugins run on and move everything to a newer platform. In a developer-blog post, the company laid out when each flagship app switches over: After Effects gets a public beta of the newer platform by November 2026 and Illustrator by spring 2027, joining Photoshop, Premiere, InDesign, and Media Encoder, which already run it. It also published the cutoffs. The Creative Cloud store stops accepting new plugins built on the old system between March 2027 and December 2028 depending on the app, the old system is off by default through December 2028, and it is removed entirely by December 2029. Adobe cited the old system's reliance on unmaintained components and Apple's plan to retire the software that lets older Mac apps run on its current chips. Its older scripting option is unaffected.

Atlassian made its new Jira dashboard extension points generally available and set a retirement date for the old ones. As it rolls out a redesigned Jira dashboard, the company added extension points that let a marketplace app place a custom widget and run background logic on the dashboard and deprecated the previous ones, which retire in May 2027. Every marketplace app that adds to a Jira dashboard has to move before then.

Why it matters: both moves re-platform extensibility onto a foundation the vendor fully controls. The systems being retired were built on aging, general-purpose technology, in Adobe's case an embedded browser and Mac support Apple is dropping, that the vendors can no longer secure or evolve. The replacements are sandboxed, purpose-built runtimes with one consistent model across a vendor's whole app line, giving the vendor tighter control over what an extension can do, better performance, and a base it can keep building on. The tradeoff is that extensibility now advances on the vendor's schedule, and a customization lasts only as long as the vendor keeps backing the platform beneath it.

Marketplace: Roblox lets creators sell items beyond their own game

Roblox began letting creators sell and surface their in-game items outside the experience that hosts them. Passes and developer products, the paid items a creator sells inside their Roblox experience, can now appear on the Roblox homepage, in search, and in the store, so a player can buy one and enter the game already owning it. A creator has to mark an item as listed and handle its purchases correctly for it to show up, and Roblox is flagging which items need fixes first. The change is rolling out now, gated per account.

Why it matters: discovery and checkout move up to the platform, so a creator's paid items can reach players who never opened their game. It turns a per-game catalog into a storefront Roblox merchandises itself.

Also worth knowing

The W3C WebExtensions Community Group held its cross-vendor call on September 24, where Chrome and Apple declined a proposal to let extensions color individual browser tabs and the group aligned a recently shipped extension interface for reading a domain's public suffix across browsers.
The Bytecode Alliance shipped Wasmtime 49, the monthly release of its widely embedded WebAssembly runtime. The controls that limit how much work untrusted code may do now also cover the load-in phase when a plugin first starts, closing a gap that let setup code run unmetered; the release also turns on built-in support for wider-integer math and adds early error-handling support to its fast baseline compiler. A day later the Alliance shipped a security patch fixing flaws that let untrusted code dodge that same resource metering.
ArchiveBox, a well-known self-hosted web archiver, reworked the tools that capture a page into a language-agnostic plugin system. An extension is now any small program that follows a published contract, in any language, rather than code written against the app itself, and users pick which plugins run on each archiving job.

On the radar

September 30: Google begins the slower-track rollout of the Workspace Studio automation features to its remaining Workspace customers.
October 6: the W3C WebAssembly Community Group holds its next call, where it is set to vote on forming a dedicated subgroup for the Component Model, the layer that lets WebAssembly plugins compose.
October 8: the W3C WebExtensions Community Group holds its next public call.
October 16: registration closes for the W3C's annual technical plenary, where the WebExtensions group plans sessions on autofill and extension security.
By November 2026: Adobe releases a public beta of its newer extension platform for After Effects.
November 3: Chrome tentatively targets shipping WebMCP in Chrome 157, until which point it remains an origin trial.
November 17: Chrome's WebMCP origin trial is scheduled to end.
March 2027: Adobe stops accepting new Photoshop plugins built on its legacy extension system, the first of its per-app cutoffs before full removal in December 2029.
May 17, 2027: Atlassian retires the legacy Jira dashboard extension points.

This Week in Extensibility is curated by Todd Schiller. Research, drafting, and fact checking are AI-assisted.

Todd Schiller - Roblox