Rename ResumeSessionPicker to StandaloneSessionPicker and add documentation

docs/features/session-resume.md

@@ -0,0 +1,74 @@
+# Session Resume
+
+Qwen Code automatically saves your conversation history, allowing you to resume previous sessions at any time.
+
+## Overview
+
+Sessions are saved automatically as you work. You can resume them either from the command line when starting Qwen Code, or from within an active session using the `/resume` command.
+
+## How Sessions Are Stored
+
+Sessions are stored as JSONL files (one JSON record per line) at:
+
+```
+~/.qwen/tmp/<project_hash>/chats/<sessionId>.jsonl
+```
+
+Each session captures:
+
+- User messages and assistant responses
+- Tool calls and their results
+- Metadata: timestamps, git branch, working directory, model used
+
+## Resuming Sessions
+
+### From the Command Line
+
+**Resume most recent session:**
+
+```bash
+qwen --continue
+```
+
+**Show session picker:**
+
+```bash
+qwen --resume
+```
+
+**Resume specific session by ID:**
+
+```bash
+qwen --resume <sessionId>
+```
+
+### From Within the App
+
+Use the `/resume` slash command to open a session picker dialog:
+
+```
+/resume
+```
+
+### Session Picker Controls
+
+- **Arrow keys** or **j/k**: Navigate between sessions
+- **Enter**: Select and resume the highlighted session
+- **B**: Toggle branch filter (show only sessions from current git branch)
+- **Escape**: Cancel and return to current session
+
+## Session List Display
+
+Each session shows:
+
+- First prompt text (truncated if long)
+- Number of messages
+- Last modified timestamp
+- Git branch name (if available)
+
+Sessions are sorted by last modified time, with most recent first.
+
+## Related Features
+
+- [Welcome Back](./welcome-back.md) - Automatic session context restoration
+- [/summary command](../cli/commands.md) - Generate project summaries for future reference