platform/plugins/CLAUDE.md

Plugins

EXTRACTING-A-PLUGIN.md is the runbook for turning a platform feature into a plugin, and EXTRACT-A-PLUGIN-PROMPT.md is the way to hand that to a fresh agent. This file is for the concepts a plugin author needs that are not procedure.

This directory holds documentation, not plugins. Every plugin is its own repository; plugins/<name>/ appears by git clone when somebody installs one, and is gitignored here.

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Affordances

DESIGN, NOT BUILT. Agreed 2026-08-19. There is no registry, no API and nothing to call yet. It is written down now because the name and the boundary are the parts that are expensive to change later, and because a plugin author who invents a different word for this will be hard to merge with afterwards.

What one is

An affordance is something the surface on the other end of the conversation offers the agent — declared by the code that implements it, and read by the agent at runtime.

Not what the agent can do. What the client will honour.

Why it needs to exist

The platform hosts the agent and never introduces itself. An agent gets a shell, a filesystem and a prompt; everything about the surface it is speaking through has to be smuggled in as prose somebody maintains by hand.

The worked example is images. Officer's chat renders markdown images — ChatImage is wired into react-markdown — but an <img> carries no bearer token, so it can only load what the browser can fetch unauthenticated. A fresh agent knows none of that. It writes ![](/home/me/chart.png), nothing renders, and nothing tells it why. The knowledge currently lives in a hand-written CLAUDE.md on one machine, which says "use a public URL" — a workaround, one step removed from the actual constraint, with nothing keeping the two in sync.

Three properties make prose the wrong container for this:

• It drifts. The file describes a workaround; the code has a reason. Neither knows about the other.
• It is per-machine. It lives in one repository, copied by hand.
• A plugin cannot contribute to it. Install a plugin that adds a surface and no agent learns it exists — which is the case that matters here, because a plugin is exactly a new surface arriving at runtime.

The boundary

Three neighbours, easily confused:

	answers
tool	what the agent can do — it acts, something happens
permission	what this account may reach
skill	instructions the agent follows
affordance	what the client will render, accept or ignore

Two tests settle most cases:

1. Would it change if the same agent talked to a different client? A phone app, a terminal, a webhook, a cron run with no human at all. If yes, it is an affordance. Rendering an image is; reading a file is not.
2. Does the agent have to guess it today? If the honest answer is "it writes the markdown and hopes", that is a missing affordance.

The rule that makes it worth having

An affordance is declared where it is implemented. ChatImage declares that images render, because ChatImage is what makes them render. The moment it becomes a list maintained somewhere else, it is the hand-written CLAUDE.md problem again with a better name — and this time with a build step.

Same posture as permissions/registry.ts, and for the same reason: one enumeration, owned by the code it describes, which cannot quietly disagree with reality.

The file

Markdown with YAML frontmatter, like every other item in capabilities/. Frontmatter is for the PLATFORM; the body is for the agent.

---
name: Image rendering
description: Use when you have an image to show the user in chat.
version: 1
---

`![alt](https://…)` renders as an image. **The user's device fetches the URL**, so it must be
reachable from there — a local path, `file://`, or anything behind authentication renders nothing,
and fails silently.

field
name	becomes the heading in the compiled block, so the agent can index it
description	when to reach for it. Costs the agent nothing — it is not sent
version	an INTEGER, not semver, matching capabilities/agents/ (agent-files.ts parses it that way). A plugin-contributed affordance sits near two version numbers and they mean different things: this integer is the revision of this text, the plugin's semver is the plugin's. Do not reconcile them

Keep the body short. Every affordance is loaded into every conversation, so it is charged to the context budget of every turn. State the constraint, name the silent failures, say what to do instead.

There is deliberately no surface field yet. It was drafted and dropped: for the image affordance it would mean what the client renders, and for the gitea one below what tooling exists on the machine — two different axes wearing one name. Everything is loaded unconditionally until that is worked out, which is fine at two files and will not be at twenty. See TODO.md.

Where they live

capabilities/affordances/
  officer/core/          ← core, installed by the setup script
    image-rendering.md
  officer/gitea/         ← contributed by the gitea plugin on install
    gitea.md

<publisher>/<plugin>, taken from the manifest verbatim — so a plugin published by officerdev lands under officerdev/. officer/core is not a plugin: it is the platform's own, shipped by the setup script from the capabilities repository. The two spellings mark two different things and should not be normalised into one. A plugin ships an affordances/ directory in its repository; installing copies it in, uninstalling removes it — the same shape as assets/ and publishAssets.

Notifications — the same shape, for push

A plugin can also declare what its push notifications MEAN. Same mechanism, different store:

capabilities/notifications/
  officerdev/music/
    catalogue.yaml

nowPlaying:
  title: 'Now playing'
  route: 'officer://music/{id}'

That becomes the code officerdev/music:nowPlaying. A push carries the code and integers — never content — and the device renders the title and follows the route. The point is that adding a notification is a server change and never an app build, because the mapping is synced to the device rather than compiled into it.

The namespace comes from where the file lands, not from what it says. Writing officer/core:test as a key in your own catalogue produces <you>/<yourplugin>:officer/core:test, not the core code — the same rule as mountPrefix, and pinned by test in src/servers/notifications/catalogue.test.ts.

An entry needs a title; body, target, route and thread are optional, thread defaults to your namespace, and unknown keys are dropped rather than forwarded to the device. Broken YAML in one plugin's catalogue is skipped without affecting anyone else's.

See docs/push-notifications.md.

A plugin-contributed one, for reference

This is the gitea plugin's, and it shows what these are for: the agent cannot discover from the filesystem that tea is authenticated, or that it should prefer git for the things git already does.

---
name: Gitea
description: Use when working with git repositories, or with Gitea issues and pull requests.
version: 1
---

For anything git already does — clone, fetch, pull, push, branches, tags — use plain `git`. It talks
to the server directly.

For anything git does not — pull requests, issues, comments, releases, creating a repository — use
`tea`. It is already logged in as the current user, with that user's own permissions. Do not
configure it, and do not ask the user for a token.

On the word

capability was taken — CAPABILITIES is the permission registry. skill was taken twice: by capabilities/skills/ here and by the wider AI ecosystem.

affordance is the exact term for what an environment offers an actor, and the precision earns the slight awkwardness: rendering an image is not a skill the agent has, it is something the client on the other end permits. Keeping that distinction in the name saves explaining it every time.