feat: agent-controlled context compaction (Claude Code style)

- Add agent-facing instructions about /compact command in system prompt
- Enhance compaction summary with workflow context (files, tools, tasks)
- Add 'What to Do Next' guidance after compaction
- Change /compact to trigger immediate compaction (not toggle)
- Extract workflow context from tool usage and messages
- Lower auto-compaction threshold to 85% for earlier triggering

The agent now knows it can use /compact when context gets long,
similar to Claude Code's approach.

session_20260216_095242.json

@@ -0,0 +1,16 @@
+{
+  "schema_version": 1,
+  "metadata": {
+    "id": "9f574f3d-c6f6-436e-9967-aaaba56148a2",
+    "title": "New Session",
+    "created_at": "2026-02-16T15:52:42.502684Z",
+    "updated_at": "2026-02-16T15:52:42.502684Z",
+    "message_count": 0,
+    "total_tokens": 0,
+    "model": "deepseek-v3.2",
+    "workspace": "/var/folders/gc/lw1tgpk97z51d30mcvbhyb400000gn/T/.tmpTtSsZw",
+    "mode": "AGENT"
+  },
+  "messages": [],
+  "system_prompt": null
+}

session_20260216_095908.json

@@ -0,0 +1,16 @@
+{
+  "schema_version": 1,
+  "metadata": {
+    "id": "a9cab85f-7ea0-44f8-a6dc-88aee23462ab",
+    "title": "New Session",
+    "created_at": "2026-02-16T15:59:08.213118Z",
+    "updated_at": "2026-02-16T15:59:08.213118Z",
+    "message_count": 0,
+    "total_tokens": 0,
+    "model": "deepseek-v3.2",
+    "workspace": "/var/folders/gc/lw1tgpk97z51d30mcvbhyb400000gn/T/.tmpT6EfcG",
+    "mode": "AGENT"
+  },
+  "messages": [],
+  "system_prompt": null
+}

session_20260216_100056.json

@@ -0,0 +1,16 @@
+{
+  "schema_version": 1,
+  "metadata": {
+    "id": "fa7764c1-15ba-4b5a-bce8-e4f939e1f838",
+    "title": "New Session",
+    "created_at": "2026-02-16T16:00:56.854336Z",
+    "updated_at": "2026-02-16T16:00:56.854336Z",
+    "message_count": 0,
+    "total_tokens": 0,
+    "model": "deepseek-v3.2",
+    "workspace": "/var/folders/gc/lw1tgpk97z51d30mcvbhyb400000gn/T/.tmpe0lg3x",
+    "mode": "AGENT"
+  },
+  "messages": [],
+  "system_prompt": null
+}

session_20260216_101655.json

@@ -0,0 +1,16 @@
+{
+  "schema_version": 1,
+  "metadata": {
+    "id": "8d3f306c-70d3-46d9-8007-10c638966197",
+    "title": "New Session",
+    "created_at": "2026-02-16T16:16:55.890410Z",
+    "updated_at": "2026-02-16T16:16:55.890410Z",
+    "message_count": 0,
+    "total_tokens": 0,
+    "model": "deepseek-v3.2",
+    "workspace": "/var/folders/gc/lw1tgpk97z51d30mcvbhyb400000gn/T/.tmpUidsSQ",
+    "mode": "AGENT"
+  },
+  "messages": [],
+  "system_prompt": null
+}

session_20260216_102128.json

@@ -0,0 +1,16 @@
+{
+  "schema_version": 1,
+  "metadata": {
+    "id": "159c08f3-9aab-435c-9f2b-370a40667710",
+    "title": "New Session",
+    "created_at": "2026-02-16T16:21:28.631837Z",
+    "updated_at": "2026-02-16T16:21:28.631837Z",
+    "message_count": 0,
+    "total_tokens": 0,
+    "model": "deepseek-v3.2",
+    "workspace": "/var/folders/gc/lw1tgpk97z51d30mcvbhyb400000gn/T/.tmpeUxI8I",
+    "mode": "AGENT"
+  },
+  "messages": [],
+  "system_prompt": null
+}

session_20260216_103041.json

@@ -0,0 +1,16 @@
+{
+  "schema_version": 1,
+  "metadata": {
+    "id": "4e6f3623-30d7-431e-8b11-d8549dac8c13",
+    "title": "New Session",
+    "created_at": "2026-02-16T16:30:41.499125Z",
+    "updated_at": "2026-02-16T16:30:41.499125Z",
+    "message_count": 0,
+    "total_tokens": 0,
+    "model": "deepseek-v3.2",
+    "workspace": "/var/folders/gc/lw1tgpk97z51d30mcvbhyb400000gn/T/.tmpjykcjh",
+    "mode": "AGENT"
+  },
+  "messages": [],
+  "system_prompt": null
+}

session_20260216_103448.json

@@ -0,0 +1,16 @@
+{
+  "schema_version": 1,
+  "metadata": {
+    "id": "0c1e5eb4-e426-4d8a-a622-80b1939e5083",
+    "title": "New Session",
+    "created_at": "2026-02-16T16:34:48.304398Z",
+    "updated_at": "2026-02-16T16:34:48.304398Z",
+    "message_count": 0,
+    "total_tokens": 0,
+    "model": "deepseek-v3.2",
+    "workspace": "/var/folders/gc/lw1tgpk97z51d30mcvbhyb400000gn/T/.tmp1bRsZy",
+    "mode": "AGENT"
+  },
+  "messages": [],
+  "system_prompt": null
+}

session_20260216_104548.json

@@ -0,0 +1,16 @@
+{
+  "schema_version": 1,
+  "metadata": {
+    "id": "ce96ab6c-6b3c-45fb-8c69-f7659e50cb03",
+    "title": "New Session",
+    "created_at": "2026-02-16T16:45:48.643707Z",
+    "updated_at": "2026-02-16T16:45:48.643707Z",
+    "message_count": 0,
+    "total_tokens": 0,
+    "model": "deepseek-v3.2",
+    "workspace": "/var/folders/gc/lw1tgpk97z51d30mcvbhyb400000gn/T/.tmpkQGlZi",
+    "mode": "AGENT"
+  },
+  "messages": [],
+  "system_prompt": null
+}

session_20260216_105657.json

@@ -0,0 +1,16 @@
+{
+  "schema_version": 1,
+  "metadata": {
+    "id": "3ea22ecd-cb0a-485b-ba2e-9f9e02d1ec74",
+    "title": "New Session",
+    "created_at": "2026-02-16T16:56:57.987857Z",
+    "updated_at": "2026-02-16T16:56:57.987857Z",
+    "message_count": 0,
+    "total_tokens": 0,
+    "model": "deepseek-v3.2",
+    "workspace": "/var/folders/gc/lw1tgpk97z51d30mcvbhyb400000gn/T/.tmpOWW4ty",
+    "mode": "AGENT"
+  },
+  "messages": [],
+  "system_prompt": null
+}

session_20260216_105739.json

@@ -0,0 +1,16 @@
+{
+  "schema_version": 1,
+  "metadata": {
+    "id": "206fc731-8181-4693-8c27-1fbc9cc8032e",
+    "title": "New Session",
+    "created_at": "2026-02-16T16:57:39.210126Z",
+    "updated_at": "2026-02-16T16:57:39.210126Z",
+    "message_count": 0,
+    "total_tokens": 0,
+    "model": "deepseek-v3.2",
+    "workspace": "/var/folders/gc/lw1tgpk97z51d30mcvbhyb400000gn/T/.tmpTNf6nn",
+    "mode": "AGENT"
+  },
+  "messages": [],
+  "system_prompt": null
+}

src/commands/mod.rs

@@ -168,7 +168,7 @@ pub const COMMANDS: &[CommandInfo] = &[
     CommandInfo {
         name: "compact",
         aliases: &[],
-        description: "Toggle auto-compaction",
+        description: "Trigger context compaction to free up space",
         usage: "/compact",
     },
     CommandInfo {

src/commands/session.rs

@@ -118,16 +118,12 @@ pub fn load(app: &mut App, path: Option<&str>) -> CommandResult {
     )
 }
 
-/// Toggle auto-compaction
-pub fn compact(app: &mut App) -> CommandResult {
-    app.auto_compact = !app.auto_compact;
-
+/// Trigger context compaction
+pub fn compact(_app: &mut App) -> CommandResult {
+    // Trigger immediate compaction via engine
     CommandResult::with_message_and_action(
-        format!(
-            "Auto-compact: {}",
-            if app.auto_compact { "ON" } else { "OFF" }
-        ),
-        AppAction::UpdateCompaction(app.compaction_config()),
+        "Context compaction triggered...".to_string(),
+        AppAction::CompactContext,
     )
 }
 
@@ -325,22 +321,15 @@ mod tests {
     fn test_compact_toggles_state() {
         let tmpdir = TempDir::new().unwrap();
         let mut app = create_test_app_with_tmpdir(&tmpdir);
-        let initial = app.auto_compact;
 
         let result = compact(&mut app);
         assert!(result.message.is_some());
         let msg = result.message.unwrap();
-        assert!(msg.contains("Auto-compact:"));
-        assert!(msg.contains(if initial { "OFF" } else { "ON" }));
-        assert_eq!(app.auto_compact, !initial);
+        assert!(msg.contains("compaction") || msg.contains("Compact"));
         assert!(matches!(
             result.action,
-            Some(AppAction::UpdateCompaction(_))
+            Some(AppAction::CompactContext)
         ));
-
-        // Toggle back
-        let _result2 = compact(&mut app);
-        assert_eq!(app.auto_compact, initial);
     }
 
     #[test]

src/compaction.rs

@@ -649,11 +649,25 @@ pub async fn compact_messages(
     // Create a summary of the unpinned portion of the conversation
     let summary = create_summary(client, &to_summarize, &config.model).await?;
 
-    // Build new message list with summary as system block
+    // Extract workflow context (files touched, tasks in progress, etc.)
+    let workflow_context = extract_workflow_context(&to_summarize, workspace);
+
+    // Build new message list with enhanced summary as system block
     let summary_block = SystemBlock {
         block_type: "text".to_string(),
         text: format!(
-            "## Conversation Summary\n\nThe following summarizes earlier context that was not pinned to the working set:\n\n{summary}\n\n---\nPinned messages follow:"
+            "## 📋 Conversation Summary (Auto-Generated)\n\n\
+             {summary}\n\n\
+             ---\n\n\
+             ## 🔍 Workflow Context\n\n\
+             {workflow_context}\n\n\
+             ---\n\n\
+             ## 💡 What to Do Next\n\n\
+             You have just resumed from a context compaction. The conversation above was summarized to save space. \
+             Review the summary and workflow context, then continue helping the user with their task. \
+             If you need more details about the summarized portion, ask the user to clarify.\n\n\
+             ---\n\n\
+             Pinned messages follow:"
         ),
         cache_control: if config.cache_summary {
             Some(CacheControl {
@@ -751,6 +765,101 @@ async fn create_summary(
     Ok(summary)
 }
 
+/// Extract workflow context from messages (files touched, tasks, etc.)
+fn extract_workflow_context(messages: &[Message], workspace: Option<&Path>) -> String {
+    let mut files_touched: Vec<String> = Vec::new();
+    let mut tools_used: Vec<String> = Vec::new();
+    let mut tasks_identified: Vec<String> = Vec::new();
+    
+    for msg in messages {
+        for block in &msg.content {
+            match block {
+                ContentBlock::ToolUse { name, input, .. } => {
+                    tools_used.push(name.clone());
+                    
+                    // Extract file paths from tool inputs
+                    if let Some(path) = extract_path_from_input(input) {
+                        if !files_touched.contains(&path) {
+                            files_touched.push(path);
+                        }
+                    }
+                }
+                ContentBlock::Text { text, .. } => {
+                    // Look for task/todo mentions
+                    if text.contains("TODO") || text.contains("task") || text.contains("need to") {
+                        let task = truncate_chars(text, 200).to_string();
+                        if !tasks_identified.contains(&task) {
+                            tasks_identified.push(task);
+                        }
+                    }
+                }
+                _ => {}
+            }
+        }
+    }
+    
+    let mut context = String::new();
+    
+    if !files_touched.is_empty() {
+        context.push_str("**Files Modified/Read:**\n");
+        for file in &files_touched {
+            if let Some(ws) = workspace {
+                let relative = Path::new(file)
+                    .strip_prefix(ws)
+                    .unwrap_or(Path::new(file))
+                    .display();
+                context.push_str(&format!("- `{}`\n", relative));
+            } else {
+                context.push_str(&format!("- `{}`\n", file));
+            }
+        }
+        context.push('\n');
+    }
+    
+    if !tools_used.is_empty() {
+        context.push_str("**Tools Used:** ");
+        context.push_str(&tools_used.join(", "));
+        context.push_str("\n\n");
+    }
+    
+    if !tasks_identified.is_empty() {
+        context.push_str("**Tasks/TODOs Identified:**\n");
+        for task in &tasks_identified {
+            context.push_str(&format!("- {}\n", task));
+        }
+        context.push('\n');
+    }
+    
+    if context.is_empty() {
+        context.push_str("No specific workflow context detected. Continue assisting the user with their current task.\n");
+    }
+    
+    context
+}
+
+/// Extract file path from tool input JSON
+fn extract_path_from_input(input: &serde_json::Value) -> Option<String> {
+    // Try common path field names
+    for key in ["path", "file", "file_path", "filename"] {
+        if let Some(path) = input.get(key).and_then(|v| v.as_str()) {
+            return Some(path.to_string());
+        }
+    }
+    
+    // Try to find path in nested objects
+    if let Some(obj) = input.as_object() {
+        for (_, value) in obj {
+            if let Some(path) = value.as_str() {
+                if path.contains('/') || path.contains('\\') || path.contains('.') {
+                    return Some(path.to_string());
+                }
+            }
+        }
+    }
+    
+    None
+}
+
 pub fn merge_system_prompts(
     original: Option<&SystemPrompt>,
     summary: Option<SystemPrompt>,

src/prompts.rs

@@ -60,6 +60,18 @@ pub fn system_prompt_for_mode_with_context(
         full_prompt = format!("{full_prompt}\n\n{summary}");
     }
 
+    // Add compaction instruction for agent modes
+    if matches!(mode, AppMode::Agent | AppMode::Yolo) {
+        full_prompt.push_str(
+            "\n\n## Context Management\n\n\
+             When the conversation gets long (you'll see a context usage indicator), you can:\n\
+             1. Use `/compact` to summarize earlier context and free up space\n\
+             2. The system will preserve important information (files you're working on, recent messages, tool results)\n\
+             3. After compaction, you'll see a summary of what was discussed and can continue seamlessly\n\n\
+             If you notice context is getting long (>80%), proactively suggest using `/compact` to the user."
+        );
+    }
+
     SystemPrompt::Text(full_prompt)
 }
 

src/tui/app.rs

@@ -46,6 +46,17 @@ fn format_welcome_banner(model: &str, workspace: &PathBuf, yolo: bool) -> String
     )
 }
 
+/// Get the agent-facing instruction about context compaction.
+/// This encourages the agent to request compaction when context gets long.
+fn get_compaction_instruction() -> &'static str {
+    "## Context Management\n\n\
+     When the conversation gets long (you'll see a context usage indicator), you can:\n\
+     1. Use `/compact` to summarize earlier context and free up space\n\
+     2. The system will preserve important information (files you're working on, recent messages, tool results)\n\
+     3. After compaction, you'll see a summary of what was discussed and can continue seamlessly\n\n\
+     If you notice context is getting long (>80%), proactively suggest using `/compact` to the user."
+}
+
 // === Types ===
 
 /// State machine for onboarding new users.
@@ -937,6 +948,7 @@ pub enum AppAction {
     ListSubAgents,
     FetchModels,
     UpdateCompaction(CompactionConfig),
+    CompactContext,
     TaskAdd {
         prompt: String,
     },

src/tui/ui.rs

@@ -1102,6 +1102,10 @@ async fn run_event_loop(
                                             .send(Op::SetCompaction { config: compaction })
                                             .await;
                                     }
+                                    AppAction::CompactContext => {
+                                        app.status_message = Some("Compacting context...".to_string());
+                                        let _ = engine_handle.send(Op::CompactContext).await;
+                                    }
                                     AppAction::TaskAdd { prompt } => {
                                         let request = NewTaskRequest {
                                             prompt: prompt.clone(),