docs: document the remote-HTTP serve mode, env vars, nginx and Mistral setup

- README + getting-started: a "Serve over HTTPS (remote MCP)" section with the
  `familiar serve` command, the FAMILIAR_HTTP_* env vars, the write-off-by-
  default note, an nginx location block (proxy_buffering off, long read
  timeout), the headless-login / copy-the-store options, and the steps to add
  it as a Mistral custom connector.
- architecture: describe the stdio/HTTP transport split, the bearer-auth gate,
  and the HTTP write default.
- CLAUDE.md: add the new commands and env vars to Commands + Architecture.

doc/getting-started.md

@@ -99,7 +99,72 @@ uv run familiar writes            # show current state
 
 Full details in [Write Safety](write-safety.md).
 
-## 7. Verify everything works
+## 7. Serve over HTTPS (remote MCP)
+
+Everything above uses **stdio** — the local transport an MCP client launches on your machine.
+To reach familiar from a **remote** MCP client (for example a [chat.mistral.ai](https://chat.mistral.ai)
+custom connector), run the opt-in **streamable-HTTP** transport instead. stdio stays the default;
+nothing here changes how `uv run familiar` behaves with no arguments.
+
+```bash
+FAMILIAR_HTTP_TOKEN=$(openssl rand -hex 32) uv run familiar serve
+```
+
+`familiar serve` binds `127.0.0.1:8080/mcp` behind a TLS-terminating reverse proxy. It **refuses to
+start without `FAMILIAR_HTTP_TOKEN`** — an internet-reachable account window must never run
+unauthenticated. A request without a valid `Authorization: Bearer <token>` gets `401` with a
+`WWW-Authenticate: Bearer` header; a valid token lets the MCP handshake through.
+
+| Variable | Default | Meaning |
+| --- | --- | --- |
+| `FAMILIAR_HTTP_TOKEN` | *(required)* | Bearer token the client must send; serve refuses to start without it. |
+| `FAMILIAR_HTTP_HOST` | `127.0.0.1` | Bind address. Leave loopback; let the proxy face the internet. |
+| `FAMILIAR_HTTP_PORT` | `8080` | Bind port. |
+| `FAMILIAR_HTTP_PATH` | `/mcp` | MCP endpoint path. |
+| `FAMILIAR_ENABLE_WRITES` | *(unset)* | In HTTP mode writes default **off**; set to `1`/`true` to opt in. |
+
+> **Writes default off over HTTP.** A network-reachable, LLM-driven endpoint should not send mail or
+> set waypoints unless you opt in explicitly with `FAMILIAR_ENABLE_WRITES=1`. (Over stdio they stay on
+> by default, as in section 6.)
+
+### nginx location block
+
+Streamable HTTP holds a long-lived response open, so turn off buffering and raise the read timeout:
+
+```nginx
+location /mcp {
+    proxy_pass http://127.0.0.1:8080/mcp;
+    proxy_http_version 1.1;
+    proxy_set_header Host $host;
+    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+    proxy_set_header X-Forwarded-Proto $scheme;
+    proxy_buffering off;          # stream events straight through
+    proxy_read_timeout 3600s;     # don't cut long-lived MCP sessions
+}
+```
+
+### Logging in on a headless server
+
+`familiar login` needs a local browser and the `localhost:8765` callback. On a headless box:
+
+- **Headless login** — print the SSO URL, authorize in any browser, paste the redirected URL back:
+
+  ```bash
+  uv run familiar login --no-browser
+  ```
+
+  The `localhost` page the browser lands on fails to load — that's expected; copy its address bar
+  (it holds the `code`) and paste it at the prompt.
+- **Copy the store** — run `familiar login` on your desktop, then copy the encrypted store
+  (`token.enc` + `key` from your `FAMILIAR_DATA_DIR`) to the server's data dir.
+
+### Add it in Mistral
+
+In [chat.mistral.ai](https://chat.mistral.ai): **Intelligence → Connectors → Add custom connector**,
+set the URL to `https://your-host/mcp`, choose **Bearer Token** auth, and paste your
+`FAMILIAR_HTTP_TOKEN`.
+
+## 8. Verify everything works
 
 ```bash
 uv run pytest          # full test suite (fails under 80% coverage)