Feat/resume conversations

src/agent/agent.ts

@@ -245,13 +245,16 @@ export class Agent {
       return query;
     }
 
-    const userMessages = inMemoryChatHistory.getUserMessages();
-    if (userMessages.length === 0) {
+    const messages = inMemoryChatHistory.getMessages();
+    if (messages.length === 0) {
       return query;
     }
 
-    const historyContext = userMessages.map((msg, i) => `${i + 1}. ${msg}`).join('\n');
-    return `Current query to answer: ${query}\n\nPrevious user queries for context:\n${historyContext}`;
+    // Include both queries and summaries for proper context
+    const historyContext = messages
+      .map((msg, i) => `${i + 1}. User: ${msg.query}\n   Assistant: ${msg.summary}`)
+      .join('\n');
+    return `Current query to answer: ${query}\n\nPrevious conversation for context:\n${historyContext}`;
   }
 
   /**

src/hooks/useModelSelection.ts

@@ -1,4 +1,4 @@
-import { useState, useCallback, useRef } from 'react';
+import { useState, useCallback, useRef, useEffect } from 'react';
 import { getSetting, setSetting } from '../utils/config.js';
 import { getProviderDisplayName, checkApiKeyExistsForProvider, saveApiKeyForProvider } from '../utils/env.js';
 import { getModelsForProvider, getDefaultModelForProvider } from '../components/ModelSelector.js';
@@ -73,6 +73,14 @@ export function useModelSelection(
   // Message history ref - shared with agent runner
   const inMemoryChatHistoryRef = useRef<InMemoryChatHistory>(new InMemoryChatHistory(model));
 
+  // Load conversation history on mount to resume previous session
+  useEffect(() => {
+    inMemoryChatHistoryRef.current.load().catch((err) => {
+      // Non-critical: app works without history, but log for debugging
+      console.warn('Failed to load conversation history:', err);
+    });
+  }, []);
+
   // Helper to complete a model switch (DRY pattern)
   const completeModelSwitch = useCallback((newProvider: string, newModelId: string) => {
     setProvider(newProvider);

src/utils/in-memory-chat-history.ts

@@ -1,7 +1,14 @@
 import { createHash } from 'crypto';
+import { readFile, writeFile, mkdir } from 'fs/promises';
+import { existsSync } from 'fs';
+import { join, dirname } from 'path';
 import { callLlm, DEFAULT_MODEL } from '../model/llm.js';
 import { z } from 'zod';
 
+const DEXTER_DIR = '.dexter';
+const CONTEXT_DIR = 'context';
+const CONTEXT_FILE = 'conversation.json';
+
 /**
  * Represents a single conversation turn (query + answer + summary)
  */
@@ -31,17 +38,71 @@ Keep summaries to 1-2 sentences that capture the key information.`;
 const MESSAGE_SELECTION_SYSTEM_PROMPT = `You are a relevance evaluator. Select which previous conversation messages are relevant to the current query.
 Return only message IDs that contain information directly useful for answering the current query.`;
 
+interface ContextFile {
+  messages: Message[];
+  model: string;
+  savedAt: string;
+}
+
 /**
- * Manages in-memory conversation history for multi-turn conversations.
+ * Manages conversation history for multi-turn conversations.
+ * Persists to disk for session resume on restart.
  * Stores user queries, final answers, and LLM-generated summaries.
  */
 export class InMemoryChatHistory {
   private messages: Message[] = [];
   private model: string;
   private relevantMessagesByQuery: Map<string, Message[]> = new Map();
+  private filePath: string;
+  private loaded = false;
 
-  constructor(model: string = DEFAULT_MODEL) {
+  constructor(model: string = DEFAULT_MODEL, baseDir: string = process.cwd()) {
     this.model = model;
+    this.filePath = join(baseDir, DEXTER_DIR, CONTEXT_DIR, CONTEXT_FILE);
+  }
+
+  /**
+   * Loads conversation context from disk.
+   * Call this on startup to resume previous session.
+   */
+  async load(): Promise<void> {
+    if (this.loaded) return;
+
+    try {
+      if (existsSync(this.filePath)) {
+        const content = await readFile(this.filePath, 'utf-8');
+        const data: ContextFile = JSON.parse(content);
+        this.messages = data.messages || [];
+        // Restore IDs to ensure consistency
+        this.messages.forEach((msg, idx) => {
+          msg.id = idx;
+        });
+      }
+    } catch {
+      // If there's any error reading/parsing, start fresh
+      this.messages = [];
+    }
+
+    this.loaded = true;
+  }
+
+  /**
+   * Saves conversation context to disk.
+   * Called automatically after adding messages.
+   */
+  private async save(): Promise<void> {
+    const dir = dirname(this.filePath);
+
+    if (!existsSync(dir)) {
+      await mkdir(dir, { recursive: true });
+    }
+
+    const data: ContextFile = {
+      messages: this.messages,
+      model: this.model,
+      savedAt: new Date().toISOString(),
+    };
+    await writeFile(this.filePath, JSON.stringify(data, null, 2), 'utf-8');
   }
 
   /**
@@ -95,6 +156,9 @@ Generate a brief 1-2 sentence summary of this answer.`;
       answer,
       summary,
     });
+
+    // Persist to disk
+    await this.save();
   }
 
   /**
@@ -197,10 +261,11 @@ Select which previous messages are relevant to understanding or answering the cu
   }
 
   /**
-   * Clears all messages and cache
+   * Clears all messages and cache, and removes persisted file
    */
-  clear(): void {
+  async clear(): Promise<void> {
     this.messages = [];
     this.relevantMessagesByQuery.clear();
+    await this.save();
   }
 }