docs: name the sibling repositories in CLAUDE.md

The marketplace, the iOS client and the Android client are checked out beside
this repo and are invisible from inside it, so a change here could break one of
them with nothing in context to say so. CLAUDE.md now lists all three by
relative path, states what each is, and — the part that matters — names the
coupling: plugin-mobile-connector for the two clients, the manifest format for
the marketplace.

The marketplace row repeats the existing rule rather than softening it: the
authoring spec is CONNECTOR_MANIFEST_GUIDE.md in that repo, edited there and
never restated here. The mcp-connectors dev-doc now uses the same relative
path instead of an absolute one under a home directory.

CLAUDE.md

@@ -16,6 +16,8 @@ Four places. **Only this file is loaded into your context automatically** — th
 - **`blueprint/project-family.md`** — the design document and source of truth, referenced by section number (§0.1 neutrality, §2 threat model, §4/§5.1 crypto + database layout, §6 filesystem, §7 MCP, §9 unlock, §11 `UserManager`, §12 auth schema, §13 reports, §14/§15 connectors, §16 LLM privacy tiers, §17 sequencing, §19). **Gitignored and not under version control.** Read it before any architectural work, and never assume a section says what you remember.
 - **`docs/`** — *not* developer documentation: it is written for the in-app LLM and mounted read-only into every user's container. See [Documentation](#documentation).
 
+Code that lives outside this repo but that a change here can break is listed under [Sibling repositories](#sibling-repositories).
+
 **Before you touch one of these areas, open its file:**
 
 | You are touching | Read |
@@ -35,6 +37,18 @@ Four places. **Only this file is loaded into your context automatically** — th
 
 A pointer is not a summary. If the table sends you to a file, that file is where the decision was recorded and why the obvious alternative was rejected — inferring it from this one instead is how a trap already paid for gets stepped on twice.
 
+## Sibling repositories
+
+Three repositories are checked out **beside** this one, at the same level as its root. They are separate git repos — own history, own `CLAUDE.md`, own release cycle — and are not part of this Cargo workspace:
+
+| Path | What it is | It concerns you when |
+| ---- | ---- | ---- |
+| `../marketplace` | The **Skald Connectors Marketplace**: the connector feed and every manifest in it. Its `CONNECTOR_MANIFEST_GUIDE.md` is the **authoritative authoring spec**; this repo deliberately keeps no copy, because two files with one name drift and the one sitting next to the connectors is the one an author actually reads. | you touch the manifest format, the feed schema, or anything `mcp::install` consumes. The spec is edited **there**, never restated here. |
+| `../skald-circle-ios` | The iOS client (Swift): a remote control for an instance — chat, projects, files, approvals — end-to-end encrypted. Pairs through `crates/plugin-mobile-connector`. | you change that plugin's wire protocol, pairing flow or push payloads. |
+| `../skald-circle-android` | The Android client (Kotlin/Gradle), same role as the iOS one. **Early stage** — the repo exists but has no commits yet. | same as above. |
+
+**Do not edit them as a side effect of work done here.** The coupling that matters is `plugin-mobile-connector`: a shipped client cannot be recompiled by this repo's build, so a protocol change is a compatibility decision, not a refactor. When a change here breaks one of them, say so and let it get its own commit in its own repo.
+
 ## What this repository is
 
 A **dedicated fork** of Skald, turning a single-user personal agent into a **multi-user assistant for a small trusted group** — positioned at families, but see the neutrality rule below.