feat: add support acp in common chat (#369)

docs/chat-summarization.md

@@ -11,7 +11,7 @@ When conversations grow long, they consume more context tokens with each message
 - Important context for continuing the conversation
 
 **Key Features:**
-- **One-click compression**: Summarize directly from the chat toolbar
+- **One-click compression**: Summarize directly from the chat bottom bar
 - **Preserves original**: Creates a new chat file, keeping the original intact
 - **Smart summaries**: AI extracts the most relevant information
 - **Markdown formatted**: Summaries are well-structured and readable
@@ -21,10 +21,23 @@ When conversations grow long, they consume more context tokens with each message
 ### Compressing a Chat
 
 1. Open any chat with conversation history
-2. Click the **Compress** button (📦) in the chat top bar
+2. Click the **Compress** button (📦) in the chat bottom bar
 3. Wait for the AI to generate the summary
 4. A new chat opens with the compressed summary
 
+### Agent Sessions: Hand Over
+
+In a chat bound to an ACP agent the same button reads **Hand over**. Instead of
+writing a compressed chat file, it summarizes the transcript using your configured
+Chat Assistant provider (the same LLM that powers compression) and starts a fresh
+agent session with the summary as its opening context. The transcript in the chat
+stays intact; only the agent-side session is replaced.
+
+The button is disabled with an explanatory tooltip when the Chat Assistant
+configuration is incomplete (provider, model, template, or URL missing), because the
+summary is generated by that configuration. Auto-compression never triggers for agent
+sessions — the agent manages its own context window.
+
 ### What Gets Preserved
 
 The summarization process:
@@ -94,9 +107,12 @@ No additional configuration is required.
 
 ## Troubleshooting
 
-### Compression Button Not Visible
-- Ensure you have an active chat with messages
-- Check that the chat top bar is visible
+### Compression Button Disabled
+- Hover the button: the tooltip explains why (for example, the Chat Assistant
+  configuration is unassigned, or an agent chat has nothing to summarize yet)
+- Assign the chat feature in Preferences → QodeAssist if the tooltip says so
+- While a compression or summary is running, the button is replaced by a progress
+  indicator with a Cancel action in the bottom bar
 
 ### Compression Fails
 - Verify your Chat Assistant provider is configured correctly
@@ -110,6 +126,4 @@ No additional configuration is required.
 
 ## Related Documentation
 
-- [Agent Roles](agent-roles.md) - Switch between AI personas
 - [File Context](file-context.md) - Attach files to chat
-- [Project Rules](project-rules.md) - Customize AI behavior