feat(PN-0): full conversation archival + EPHEMERAL disconnect (#51)

Archive complete conversations to archives/conversations/ on session
end, server shutdown, and context compaction. EPHEMERAL.md becomes a
standalone lightweight summary — no longer promoted to archives.

Two parallel paths on session end: full conversation serialized to
grep-searchable markdown archive, brief summary written to EPHEMERAL
for next-session orientation. Fixes EPHEMERAL path to memory/EPHEMERAL.md
(matching what the system prompt builder reads).

New module: src/session.rs with conversation_to_markdown(),
archive_conversation(), and end_session(). Adds root_dir to AppState
for efficient access. 9 new tests.

Author: dnacenta

src/chat/repl.rs

@@ -66,6 +66,9 @@ pub async fn run(
             provider,
             config.llm.context_budget,
             config.llm.max_tokens,
+            root_dir,
+            entity_name,
+            "repl",
         )
         .await;
 
@@ -180,68 +183,12 @@ pub async fn run(
         }
     }
 
-    // Save session to EPHEMERAL.md
-    save_session(root_dir, entity_name, &conversation);
+    // Archive full conversation + write EPHEMERAL summary
+    crate::session::end_session(root_dir, entity_name, &conversation, "repl", "session-end");
 
     Ok(())
 }
 
-/// Save a brief session summary to EPHEMERAL.md.
-fn save_session(root_dir: &Path, entity_name: &str, conversation: &[Message]) {
-    // Only save if there was actual conversation
-    let message_count = conversation.len();
-    if message_count == 0 {
-        return;
-    }
-
-    let ephemeral_path = root_dir.join("EPHEMERAL.md");
-
-    let now = chrono::Utc::now().format("%Y-%m-%d %H:%M UTC");
-
-    // Collect user messages for the summary
-    let user_messages: Vec<&str> = conversation
-        .iter()
-        .filter_map(|m| {
-            if matches!(m.role, Role::User) {
-                if let MessageContent::Text(ref t) = m.content {
-                    Some(t.as_str())
-                } else {
-                    None
-                }
-            } else {
-                None
-            }
-        })
-        .collect();
-
-    let topics: Vec<&str> = user_messages.iter().take(5).copied().collect();
-
-    let mut content = format!("## CLI Chat Session — {}\n\n", now);
-    content.push_str(&format!(
-        "Conversation with {} ({} messages)\n\n",
-        entity_name, message_count
-    ));
-    content.push_str("### Topics discussed\n\n");
-    for topic in &topics {
-        // Truncate long messages
-        let display = if topic.len() > 80 {
-            format!("{}...", &topic[..77])
-        } else {
-            topic.to_string()
-        };
-        content.push_str(&format!("- {}\n", display));
-    }
-    if user_messages.len() > 5 {
-        content.push_str(&format!("- ...and {} more\n", user_messages.len() - 5));
-    }
-
-    if let Err(e) = std::fs::write(&ephemeral_path, content) {
-        eprintln!("  \x1b[33mwarning\x1b[0m  could not save session: {}", e);
-    } else {
-        println!("  \x1b[2msession saved to EPHEMERAL.md\x1b[0m");
-    }
-}
-
 /// Print a tool execution indicator (dimmed).
 fn print_tool_indicator(name: &str, input: &serde_json::Value) {
     let detail = match name {

src/context.rs

@@ -1,3 +1,5 @@
+use std::path::Path;
+
 use echo_system_types::llm::{ContentBlock, LmProvider, Message, MessageContent, Role};
 
 /// Default context budget in estimated tokens (leaves room for system prompt + response).
@@ -89,6 +91,9 @@ pub async fn compact_if_needed(
     provider: &dyn LmProvider,
     context_budget: usize,
     max_tokens: u32,
+    root_dir: &Path,
+    entity_name: &str,
+    channel: &str,
 ) {
     let budget = if context_budget > 0 {
         context_budget
@@ -125,6 +130,17 @@ pub async fn compact_if_needed(
     }
 
     let old_messages = &conversation[..split_at];
+
+    // Archive the messages about to be compacted
+    let meta = crate::session::ArchiveMeta {
+        trigger: "compaction".to_string(),
+        channel: channel.to_string(),
+        entity_name: entity_name.to_string(),
+    };
+    if let Err(e) = crate::session::archive_conversation(root_dir, old_messages, &meta) {
+        tracing::warn!("Failed to archive compacted messages: {}", e);
+    }
+
     let summary_input = build_summary_prompt(old_messages);
 
     let summarize_prompt = format!(

src/init/wizard.rs

@@ -243,6 +243,7 @@ fn create_directory_structure(dir: &Path) -> Result<(), Box<dyn std::error::Erro
         "archives/curiosity",
         "archives/thoughts",
         "archives/praxis",
+        "archives/conversations",
         "plugins",
         "logs",
     ];

src/main.rs

@@ -11,6 +11,7 @@ mod pidfile;
 mod plugins;
 mod scheduler;
 mod server;
+mod session;
 mod tools;
 
 #[derive(Parser)]

src/server/auth.rs

@@ -103,6 +103,7 @@ mod tests {
             system_prompt: RwLock::new(String::new()),
             tools: ToolRegistry::new(),
             event_bus: Arc::new(EventBus::new(16)),
+            root_dir: std::env::temp_dir(),
         })
     }
 

src/server/e2e_tests.rs

@@ -134,6 +134,7 @@ fn build_state(provider: MockProvider, tools: ToolRegistry) -> Arc<AppState> {
         system_prompt: RwLock::new("You are a test entity.".to_string()),
         tools,
         event_bus: Arc::new(EventBus::new(16)),
+        root_dir: std::env::temp_dir(),
     })
 }
 

src/server/handlers/chat.rs

@@ -80,6 +80,9 @@ pub async fn chat(
         state.provider.as_ref(),
         state.config.llm.context_budget,
         state.config.llm.max_tokens,
+        &state.root_dir,
+        &state.config.entity.name,
+        &req.channel,
     )
     .await;
 

src/server/mod.rs

@@ -7,6 +7,7 @@ pub mod prompt;
 pub mod rate_limit;
 pub mod trust;
 
+use std::path::PathBuf;
 use std::sync::Arc;
 
 use axum::middleware;
@@ -32,6 +33,7 @@ pub struct AppState {
     pub system_prompt: RwLock<String>,
     pub tools: ToolRegistry,
     pub event_bus: Arc<EventBus>,
+    pub root_dir: PathBuf,
 }
 
 pub async fn start(config: Config) -> Result<(), Box<dyn std::error::Error>> {
@@ -95,6 +97,7 @@ pub async fn start(config: Config) -> Result<(), Box<dyn std::error::Error>> {
         system_prompt: RwLock::new(system_prompt),
         tools,
         event_bus: Arc::clone(&event_bus),
+        root_dir: root_dir.clone(),
     });
 
     // Load schedule and intent queue, start scheduler
@@ -142,7 +145,7 @@ pub async fn start(config: Config) -> Result<(), Box<dyn std::error::Error>> {
             Arc::clone(&state),
             auth::require_auth,
         ))
-        .with_state(state)
+        .with_state(Arc::clone(&state))
         .layer(middleware::from_fn_with_state(
             limiter,
             rate_limit::rate_limit,
@@ -171,6 +174,20 @@ pub async fn start(config: Config) -> Result<(), Box<dyn std::error::Error>> {
         .with_graceful_shutdown(shutdown)
         .await?;
 
+    // Archive conversation on shutdown
+    {
+        let conversation = state.conversation.read().await;
+        if !conversation.is_empty() {
+            crate::session::end_session(
+                &root_dir,
+                &config.entity.name,
+                &conversation,
+                "http",
+                "server-shutdown",
+            );
+        }
+    }
+
     // Clean up plugins on shutdown
     plugin_manager.stop_all().await;