feat: enforce default session daemon isolation and bump 0.16.3-fork.4

docs/src/app/commands/page.mdx

@@ -279,10 +279,12 @@ agent-browser state clean --older-than <days>  # Delete old states
 
 ```bash
 agent-browser session                 # Show current session name
-agent-browser session list            # List active sessions
+agent-browser session list            # List active sessions (auto-cleans stale entries)
 agent-browser --parallel worker-a open https://example.com  # Isolated runtime for parallel AI tasks
 ```
 
+When a default-session command starts, all non-default daemon sessions are reaped to avoid stale daemon reuse.
+
 ## Daemon lifetime
 
 By default, daemon processes auto-shutdown after 10 minutes of inactivity.
@@ -327,7 +329,7 @@ agent-browser reload                  # Reload page
 --auto-connect           # Auto-discover and connect to running Chrome
 --tab-group <name>       # Base title for agent tab groups (CDP plugin mode)
 --tab-group-plugin-id <id> # Expected extension ID for tab-group handshake
---parallel <name>        # Isolated runtime channel for parallel AI runs (maps to parallel-<name>)
+--parallel <name>        # Isolated runtime channel for parallel AI runs (maps to parallel-<name>; reaped when default session starts)
 --resident               # Keep daemon running; disable 10-minute idle auto-shutdown
 --wait-until <mode>      # Navigation wait strategy for open/navigate (load, domcontentloaded, networkidle)
 --debug                  # Debug output (includes stealth connection type + capabilities)

docs/src/app/configuration/page.mdx

@@ -371,6 +371,7 @@ session window isolation controls, activation guard toggles, empty-group cleanup
 ```
 
 Use this for stateless throughput tasks. For authenticated flows, prefer a stable `sessionName`.
+When a default-session command runs, non-default daemon sessions are reaped.
 
 ## CLI-only daemon lifecycle flag
 
@@ -504,7 +505,7 @@ These environment variables configure additional daemon and runtime behavior:
         <code>AGENT_BROWSER_PARALLEL</code>
       </td>
       <td>
-        Isolated runtime channel name for parallel AI runs (maps to <code>parallel-&lt;name&gt;</code>).
+        Isolated runtime channel name for parallel AI runs (maps to <code>parallel-&lt;name&gt;</code>). Non-default daemons are reaped when a default-session command starts.
       </td>
       <td>(none)</td>
     </tr>

docs/src/app/sessions/page.mdx

@@ -17,6 +17,7 @@ agent-browser --parallel worker-a session
 
 # Show active daemon sessions
 agent-browser session list
+# stale entries are auto-cleaned during listing
 ```
 
 ## Session isolation
@@ -40,6 +41,11 @@ agent-browser --parallel worker-b open https://example.org
 
 `--parallel` is intended for stateless throughput tasks (navigation/extraction/checks). For authenticated flows, use a stable `--session-name`.
 
+Default session isolation policy:
+
+- Running a default-session command reaps all non-default daemon sessions (`parallel-*` and legacy named channels).
+- This keeps the primary `default` runtime channel free from stale daemon reuse.
+
 For long-running workers, add `--resident` to disable idle auto-shutdown:
 
 ```bash
@@ -195,7 +201,7 @@ agent-browser set headers '{"X-Custom-Header": "value"}'
       <td>
         <code>AGENT_BROWSER_PARALLEL</code>
       </td>
-      <td>Isolated runtime channel name for parallel AI runs (maps to <code>parallel-&lt;name&gt;</code>)</td>
+      <td>Isolated runtime channel name for parallel AI runs (maps to <code>parallel-&lt;name&gt;</code>). Non-default daemons are reaped when a default-session command starts.</td>
     </tr>
     <tr>
       <td>