Add Cline provider and Nix flake support

CLAUDE.md

@@ -4,7 +4,7 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 
 ## Project Overview
 
-Mysti is a VSCode extension providing a unified AI coding assistant interface supporting multiple AI backends (Claude Code CLI, OpenAI Codex CLI, and Google Gemini CLI). It features sidebar/tab chat panels, conversation persistence, multi-agent brainstorm mode (select 2 of 3 agents), permission controls, and plan selection.
+Mysti is a VSCode extension providing a unified AI coding assistant interface supporting multiple AI backends (Claude Code CLI, OpenAI Codex CLI, Google Gemini CLI, and Cline). It features sidebar/tab chat panels, conversation persistence, multi-agent brainstorm mode (select 2 of 4 agents), permission controls, and plan selection.
 
 ## Build Commands
 
@@ -58,13 +58,14 @@ extension.ts (entry)
             └── Providers (CLI integrations)
                 ├── ClaudeCodeProvider (extends BaseCliProvider)
                 ├── CodexProvider (extends BaseCliProvider)
-                └── GeminiProvider (extends BaseCliProvider)
+                ├── GeminiProvider (extends BaseCliProvider)
+                └── ClineProvider (extends BaseCliProvider)
 ```
 
 ### Key Design Decisions
 
 - **Per-panel isolation**: Each webview panel (sidebar or tab) has independent state, conversation, and child process
-- **CLI-based providers**: Spawn `claude`/`codex`/`gemini` CLI with `--output-format stream-json`, parse line-delimited JSON events
+- **CLI-based providers**: Spawn `claude`/`codex`/`gemini`/`cline` CLI with `--output-format stream-json`, parse line-delimited JSON events
 - **AsyncGenerator streaming**: Providers yield `StreamChunk` items for real-time response updates
 - **Webview communication**: Extension ↔ webview via `postMessage()` with typed `WebviewMessage`
 
@@ -141,6 +142,24 @@ Libraries:
 4. Add to `ProviderType` union in `src/types.ts`
 5. Add configuration options in `package.json`
 
+## Cline Provider Notes
+
+Cline is an autonomous coding agent that can use the CLI, editor, and browser. Key differences from other providers:
+
+**Installation**: Cline is primarily distributed as a VSCode extension (`ext install saoudrizwan.claude-dev`).
+
+**CLI Path**: The provider looks for the Cline binary in:
+- VSCode extensions directory (`~/.vscode/extensions/saoudrizwan.claude-dev-*/`)
+- Configured path via `mysti.clinePath` setting
+
+**Authentication**: Cline uses API keys configured in its own settings (Anthropic API, OpenRouter, etc.). The Mysti provider checks if an API key is configured.
+
+**Streaming Format**: Cline uses a similar stream-json format to Claude Code, making integration straightforward.
+
+**Models**: Cline supports the same Claude models (Sonnet 4.5, Opus 4.5, Haiku 4.5) as well as other providers via OpenRouter.
+
+**File**: `src/providers/cline/ClineProvider.ts`
+
 ### Adding a New Persona (Markdown-based)
 
 **Current count**: 16 core personas in `resources/agents/core/personas/`

flake.nix

@@ -0,0 +1,54 @@
+{
+  description = "Mysti - AI Coding Agent VSCode Extension";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils, ... }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+      in
+      {
+        devShells.default = pkgs.mkShell {
+          buildInputs = with pkgs; [
+            # Node.js and tools
+            nodejs_20
+            nodePackages.npm
+            nodePackages.typescript
+
+            # Linting
+            nodePackages.eslint
+            # Packaging (use npx vsce if vsce is not available)
+            vsce
+          ];
+
+          shellHook = ''
+            echo "Mysti Development Environment"
+            echo "=================================="
+            echo ""
+            echo "Available commands:"
+            echo "  npm run compile          - Production build"
+            echo "  npm run watch            - Development build with watch mode"
+            echo "  npm run lint             - ESLint check"
+            echo "  npm run sync-agents      - Sync agent definitions"
+            echo "  npx vsce package         - Package as .vsix"
+            echo ""
+            echo "Press F5 in VSCode to launch Extension Development Host"
+            echo ""
+
+            # Set up Node environment
+            export NODE_ENV=development
+
+            # Ensure npm dependencies are installed
+            if [ ! -d "node_modules" ]; then
+              echo "Installing npm dependencies..."
+              npm install
+            fi
+          '';
+        };
+      }
+    );
+}