stack-essentials: scaffold-extension-repo skill + extension repo naming convention

CONTRIBUTING.md

@@ -314,6 +314,8 @@ Because a `marketplace.json` can only reference plugins inside its own repo (see
 └── rules/<bundle>/                   # optional rule bundle(s)
 ```
 
+**Naming** — new extension repos follow `infinum/ai-{type}-{name}[-private]`: `{type}` is `team` or `project`, `{name}` is the kebab-case team or client name, and `-private` is appended exactly when the repo is private, so visibility is readable from the name (`infinum/ai-team-javascript`, `infinum/ai-team-javascript-private`, `infinum/ai-team-bizdev-private`, `infinum/ai-project-<client>-private`). The marketplace name mirrors it: `infinum-ai-team-javascript`. A team can have a public repo and a `-private` companion, the same split as the two core repos, `infinum/ai` and `infinum/ai-private` (which sit outside the template; `ai-private` is layered on with the same `--extend` mechanism but is a core repo, not a team or project one). The `stack-essentials` plugin ships a skill that proposes the names and generates the skeleton: `/stack-essentials:scaffold-extension-repo`.
+
 **Install** — pass `--extend` to the public installer (repeatable; value is a GitHub `owner/repo` or a local checkout path):
 
 ```bash

MARKETPLACE.md

@@ -8,11 +8,11 @@ Skills are slash commands you invoke directly in your AI tool — they carry str
 
 ## Essentials (auto-installed)
 
-The setup script enables these baseline plugins for everyone — they ship cross-cutting plumbing rather than user-invocable skills.
+The setup script enables these baseline plugins for everyone — they ship cross-cutting plumbing, plus the one skill everyone should have at hand: scaffolding a new extension repo.
 
 | Plugin                                                                          | What it does                                                                                                                                                                                                            | Cowork                                                  |
 | ------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------- |
-| [`stack-essentials`](plugins/stack-essentials/)                                 | SessionStart hook that prints a one-line banner when `infinum/ai` has new commits on `main` since your last installer run. One `git ls-remote` per machine per 24h (uses your existing git credentials), silent on failure. Disable with `INFINUM_STACK_SKIP_UPDATE_CHECK=1` or `/plugin disable stack-essentials`. | Untested — the `SessionStart` hook fires in Cowork, but its update check (`git ls-remote` to GitHub) is egress-blocked there, so the banner is a silent no-op regardless. Pending live verification. |
+| [`stack-essentials`](plugins/stack-essentials/) | Baseline plumbing for the Infinum AI Stack — flags stale local rules at session start so you know when to re-run the installer, and scaffolds new extension-marketplace repositories (infinum/ai-{type}-{name}[-private]) for team- or project-specific tooling. The `scaffold-extension-repo` skill is invoked as `/stack-essentials:scaffold-extension-repo`. | Untested — the `SessionStart` hook fires in Cowork, but its update check (`git ls-remote` to GitHub) is egress-blocked there, so the banner is a silent no-op regardless. Pending live verification. The `scaffold-extension-repo` skill is Not ready — shells out to local `git`, the `gh` CLI, and `pnpm` to initialise, create, and verify the repository. |
 
 ---
 

plugins/stack-essentials/.claude-plugin/plugin.json

@@ -1,11 +1,14 @@
 {
   "name": "stack-essentials",
-  "version": "1.0.0",
-  "description": "Baseline notifications for the Infinum AI Stack — flags stale local rules at session start so you know when to re-run the installer.",
+  "version": "1.1.0",
+  "description": "Baseline plumbing for the Infinum AI Stack — flags stale local rules at session start so you know when to re-run the installer, and scaffolds new extension-marketplace repositories (infinum/ai-{type}-{name}[-private]) for team- or project-specific tooling.",
   "keywords": [
     "infinum",
     "essentials",
     "notifications",
-    "updates"
+    "updates",
+    "extension",
+    "marketplace",
+    "scaffold"
   ]
 }

plugins/stack-essentials/README.md

@@ -2,6 +2,8 @@
 
 Baseline plumbing for the Infinum AI Stack. Installed automatically by `bin/install.js` (you don't need to opt in via the `/plugin` UI).
 
+It ships two things: a `SessionStart` update-notification hook (below) and one skill, [`scaffold-extension-repo`](skills/scaffold-extension-repo/), which walks you through creating a new extension-marketplace repository (`infinum/ai-{type}-{name}[-private]`) for team- or project-specific plugins and rules. Invoke it with `/stack-essentials:scaffold-extension-repo`; see its README for the naming convention and flow.
+
 ## What it does
 
 Adds a `SessionStart` hook that compares the HEAD commit SHA of `main` on `github.com/infinum/ai` against the SHA recorded in `~/.claude/infinum/.manifest.json` at your last installer run. When they differ, a newer version of the workspace installer is available, so the hook prints a banner on stderr at session start:

plugins/stack-essentials/skills/scaffold-extension-repo/README.md

@@ -0,0 +1,60 @@
+# scaffold-extension-repo
+
+Scaffold a new **extension marketplace** — a repository holding team- or project-specific plugins and rule bundles that is layered on top of the public `infinum/ai` base with the installer's `--extend` flag.
+
+## Usage
+
+```
+/stack-essentials:scaffold-extension-repo
+```
+
+(Plugin-installed skills are namespaced as `/<plugin>:<skill>`. `stack-essentials` is installed for everyone by the installer, so the skill is available without opting in.)
+
+The skill walks you through a guided flow:
+
+1. **Say what you are creating** — a team repo or a project repo, its name, and whether it should be public, private, or both.
+2. **Confirm the proposed names** — repository and marketplace names following `infinum/ai-{type}-{name}[-private]`.
+3. **Get the skeleton** — a copy of the bundled [`template/`](template/) with the names filled in: `marketplace.json`, a README with the exact install command, agent instructions, and optionally a first plugin and a rule bundle. Everything the owning team must write is marked `TODO`.
+4. **Optionally create the GitHub repo** — the skill asks before running `gh repo create`.
+5. **Verify** — a local-path install against the real installer, then clean-up.
+
+## The template
+
+[`template/`](template/) is a complete extension repository with `__PLACEHOLDER__` names. You can also use it by hand: copy the directory, rename the placeholder folders, search-and-replace the placeholders, delete the optional parts you do not need (`plugins/`, `rules/`, the `<!-- private-only -->` block in the README), and fill in the `TODO`s.
+
+| Placeholder | Meaning |
+|---|---|
+| `__REPO_NAME__` | repository name without `infinum/`, e.g. `ai-team-javascript-private` |
+| `__MARKETPLACE_NAME__` | `infinum-` + repo name, e.g. `infinum-ai-team-javascript-private` |
+| `__NAME_PREFIX__` | the `{name}` part; prefix for plugin, bundle and rule names |
+| `__OWNER_LABEL__` / `__OWNER__` | human label (`JavaScript team`) / maintainer |
+| `__VISIBILITY__` | `public` or `private` |
+| `__PLUGIN_NAME__` / `__SKILL_NAME__` | first plugin and its first skill |
+| `__BUNDLE_NAME__` / `__RULE_NAME__` | first rule bundle and its first rule file |
+
+## Naming convention
+
+```
+infinum/ai-{type}-{name}[-private]
+```
+
+| Situation | Repository |
+|---|---|
+| JavaScript team, shareable conventions | `infinum/ai-team-javascript` |
+| JavaScript team, internal companion | `infinum/ai-team-javascript-private` |
+| Bizdev team — sensitive, no public half | `infinum/ai-team-bizdev-private` |
+| .NET team | `infinum/ai-team-dotnet` |
+| Client project | `infinum/ai-project-<client>-private` |
+
+`-private` is present exactly when the repository is private, so the name alone tells you what to expect. The marketplace name mirrors the repo: `infinum-ai-team-javascript`. The two core repos, `infinum/ai` and `infinum/ai-private`, sit outside the template (`ai-private` is installed with the same `--extend` mechanism, but it is a core repo, not a team or project one).
+
+## When to use
+
+| Situation | Use this skill? |
+|---|---|
+| A team wants to collect its rules and skills in one shared place | Yes — a team repo |
+| A project spans several code repositories and shares tooling between them | Yes — a project repo |
+| A skill or rule is useful to every Infinum engineer | No — open a PR against `infinum/ai` |
+| A rule is only relevant to one code repository | No — commit it to that repo's `.claude/` folder |
+
+Background: [CONTRIBUTING.md — Extending with additional marketplaces](https://github.com/infinum/ai/blob/main/CONTRIBUTING.md#extending-with-additional-marketplaces).