fix: lock main session deletion

docs/agent-send.md

@@ -11,7 +11,7 @@ read_when:
 - Required: `--message <text>`
 - Session selection:
   - If `--session-id` is given, reuse it.
-  - Else if `--to <e164>` is given, derive the session key from `session.scope` (direct chats collapse to `session.mainKey`).
+  - Else if `--to <e164>` is given, derive the session key from `session.scope` (direct chats collapse to `main`, or `global` when scope is global).
 - Runs the embedded Pi agent (configured via `agent`).
 - Thinking/verbose:
   - Flags `--thinking <off|minimal|low|medium|high>` and `--verbose <on|off>` persist into the session store.

docs/clawd.md

@@ -138,8 +138,7 @@ Example:
   session: {
     scope: "per-sender",
     resetTriggers: ["/new", "/reset"],
-    idleMinutes: 10080,
-    mainKey: "main"
+    idleMinutes: 10080
   }
 }
 ```

docs/configuration.md

@@ -620,7 +620,7 @@ Controls session scoping, idle expiry, reset triggers, and where the session sto
     idleMinutes: 60,
     resetTriggers: ["/new", "/reset"],
     store: "~/.clawdis/sessions/sessions.json",
-    mainKey: "main",
+    // mainKey is ignored; primary key is fixed to "main"
     sendPolicy: {
       rules: [
         { action: "deny", match: { surface: "discord", chatType: "group" } }

docs/heartbeat.md

@@ -50,7 +50,7 @@ message. If the reply is only `HEARTBEAT_OK`, it is dropped.
 - `prompt`: optional override for the heartbeat body (default: `HEARTBEAT`).
 
 ## Behavior
-- Runs in the main session (`session.mainKey`, or `global` when scope is global).
+- Runs in the main session (`main`, or `global` when scope is global).
 - Uses the main lane queue; if requests are in flight, the wake is retried.
 - Empty output or `HEARTBEAT_OK` is treated as “ok” and does **not** keep the
   session alive (`updatedAt` is restored).

docs/mac/webchat.md

@@ -5,7 +5,7 @@ read_when:
 ---
 # Web Chat (macOS app)
 
-The macOS menu bar app shows the WebChat UI as a native SwiftUI view and reuses the **primary Clawd session** (`main` by default, configurable via `session.mainKey`).
+The macOS menu bar app shows the WebChat UI as a native SwiftUI view and reuses the **primary Clawd session** (`main`, or `global` when scope is global).
 
 - **Local mode**: connects directly to the local Gateway WebSocket.
 - **Remote mode**: forwards the Gateway WebSocket control port over SSH and uses that as the data plane.

docs/session.md

@@ -5,7 +5,7 @@ read_when:
 ---
 # Session Management
 
-Clawdis treats **one session as primary**. By default the canonical key is `main` for every direct chat; no configuration is required. You can rename it via `session.mainKey` if you really want, but there is still only a single primary session. Older/local sessions can stay on disk, but only the primary key is used for desktop/web chat and direct agent calls.
+Clawdis treats **one session as primary**. The canonical key is fixed to `main` for direct chats (or `global` when scope is global); no configuration is required. `session.mainKey` is ignored. Older/local sessions can stay on disk, but only the primary key is used for desktop/web chat and direct agent calls.
 
 ## Gateway is the source of truth
 All session state is **owned by the gateway** (the “master” Clawdis). UI clients (macOS app, WebChat, etc.) must query the gateway for session lists and token counts instead of reading local files.
@@ -67,7 +67,7 @@ Runtime override (owner only):
     idleMinutes: 120,
     resetTriggers: ["/new", "/reset"],
     store: "~/.clawdis/sessions/sessions.json",
-    mainKey: "main"           // optional rename; still a single primary
+    // mainKey is ignored; primary key is fixed to "main"
   }
 }
 ```

docs/tui.md

@@ -28,7 +28,7 @@ Use SSH tunneling or Tailscale to reach the Gateway WS.
 - `--url <url>`: Gateway WebSocket URL (defaults to config `gateway.remote.url` or `ws://127.0.0.1:18789`).
 - `--token <token>`: Gateway token (if required).
 - `--password <password>`: Gateway password (if required).
-- `--session <key>`: Session key (default: `session.mainKey` or `main`).
+- `--session <key>`: Session key (default: `main`, or `global` when scope is global).
 - `--deliver`: Deliver assistant replies to the provider (default off).
 - `--thinking <level>`: Override thinking level for sends.
 - `--timeout-ms <ms>`: Agent timeout in ms (default 30000).