feat: add ability to configure the agent (also theme switcher) (#3)

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### Issue

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### Attestations

- [ ] I have read and agree to the [Code of Conduct](https://docs.nhcarrigan.com/community/coc/)
- [ ] I have read and agree to the [Community Guidelines](https://docs.nhcarrigan.com/community/guide/).
- [ ] My contribution complies with the [Contributor Covenant](https://docs.nhcarrigan.com/dev/covenant/).

### Dependencies

- [ ] I have pinned the dependencies to a specific patch version.

### Style

- [ ] I have run the linter and resolved any errors.
- [ ] My pull request uses an appropriate title, matching the conventional commit standards.
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### Tests

- [ ] My contribution adds new code, and I have added tests to cover it.
- [ ] My contribution modifies existing code, and I have updated the tests to reflect these changes.
- [ ] All new and existing tests pass locally with my changes.
- [ ] Code coverage remains at or above the configured threshold.

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Reviewed-on: #3
Co-authored-by: Naomi Carrigan <commits@nhcarrigan.com>
Co-committed-by: Naomi Carrigan <commits@nhcarrigan.com>

src-tauri/src/wsl_bridge.rs

@@ -4,10 +4,12 @@ use std::process::{Child, ChildStdin, Command, Stdio};
 use std::sync::Arc;
 use std::thread;
 use tauri::{AppHandle, Emitter};
+use tempfile::NamedTempFile;
 
 #[cfg(target_os = "windows")]
 use std::os::windows::process::CommandExt;
 
+use crate::config::ClaudeStartOptions;
 use crate::types::{CharacterState, ClaudeMessage, ConnectionStatus, ContentBlock, StateChangeEvent, OutputEvent, PermissionPromptEvent};
 
 const SEARCH_TOOLS: [&str; 5] = ["Read", "Glob", "Grep", "WebSearch", "WebFetch"];
@@ -69,6 +71,7 @@ pub struct WslBridge {
     stdin: Option<ChildStdin>,
     working_directory: String,
     session_id: Option<String>,
+    mcp_config_file: Option<NamedTempFile>,
 }
 
 impl WslBridge {
@@ -78,22 +81,50 @@ impl WslBridge {
             stdin: None,
             working_directory: String::new(),
             session_id: None,
+            mcp_config_file: None,
         }
     }
 
-    pub fn start(&mut self, app: AppHandle, working_dir: &str, allowed_tools: Vec<String>) -> Result<(), String> {
+    pub fn start(&mut self, app: AppHandle, options: ClaudeStartOptions) -> Result<(), String> {
         if self.process.is_some() {
             return Err("Process already running".to_string());
         }
 
-        self.working_directory = working_dir.to_string();
+        let working_dir = &options.working_dir;
+        self.working_directory = working_dir.clone();
 
         emit_connection_status(&app, ConnectionStatus::Connecting);
 
+        // Create temp file for MCP config if provided
+        let mcp_config_path = if let Some(ref mcp_json) = options.mcp_servers_json {
+            if !mcp_json.trim().is_empty() {
+                // Validate JSON before writing
+                serde_json::from_str::<serde_json::Value>(mcp_json)
+                    .map_err(|e| format!("Invalid MCP servers JSON: {}", e))?;
+
+                let mut temp_file = NamedTempFile::new()
+                    .map_err(|e| format!("Failed to create temp file for MCP config: {}", e))?;
+                temp_file
+                    .write_all(mcp_json.as_bytes())
+                    .map_err(|e| format!("Failed to write MCP config: {}", e))?;
+                temp_file
+                    .flush()
+                    .map_err(|e| format!("Failed to flush MCP config: {}", e))?;
+
+                let path = temp_file.path().to_string_lossy().to_string();
+                self.mcp_config_file = Some(temp_file);
+                Some(path)
+            } else {
+                None
+            }
+        } else {
+            None
+        };
+
         // Detect if we're running inside WSL or on Windows
         let is_wsl = detect_wsl();
         eprintln!("[DEBUG] is_wsl: {}", is_wsl);
-        eprintln!("[DEBUG] allowed_tools: {:?}", allowed_tools);
+        eprintln!("[DEBUG] options: {:?}", options);
 
         let mut command = if is_wsl {
             // Running inside WSL - call claude directly
@@ -111,12 +142,39 @@ impl WslBridge {
                 "--verbose",
             ]);
 
+            // Add model if specified
+            if let Some(ref model) = options.model {
+                if !model.is_empty() {
+                    cmd.args(["--model", model]);
+                }
+            }
+
             // Add allowed tools if any
-            for tool in &allowed_tools {
+            for tool in &options.allowed_tools {
                 cmd.args(["--allowedTools", tool]);
             }
 
+            // Add custom instructions as system prompt if specified
+            if let Some(ref instructions) = options.custom_instructions {
+                if !instructions.is_empty() {
+                    cmd.args(["--system-prompt", instructions]);
+                }
+            }
+
+            // Add MCP config if provided
+            if let Some(ref mcp_path) = mcp_config_path {
+                cmd.args(["--mcp-config", mcp_path]);
+            }
+
             cmd.current_dir(working_dir);
+
+            // Set API key as environment variable if specified
+            if let Some(ref api_key) = options.api_key {
+                if !api_key.is_empty() {
+                    cmd.env("ANTHROPIC_API_KEY", api_key);
+                }
+            }
+
             cmd
         } else {
             // Running on Windows - use wsl with bash login shell to ensure PATH is loaded
@@ -125,15 +183,45 @@ impl WslBridge {
 
             // Build the claude command with all arguments
             let mut claude_cmd = format!(
-                "cd '{}' && claude --output-format stream-json --input-format stream-json --verbose",
+                "cd '{}' && ",
                 working_dir
             );
 
+            // Set API key as environment variable if specified
+            if let Some(ref api_key) = options.api_key {
+                if !api_key.is_empty() {
+                    claude_cmd.push_str(&format!("ANTHROPIC_API_KEY='{}' ", api_key));
+                }
+            }
+
+            claude_cmd.push_str("claude --output-format stream-json --input-format stream-json --verbose");
+
+            // Add model if specified
+            if let Some(ref model) = options.model {
+                if !model.is_empty() {
+                    claude_cmd.push_str(&format!(" --model '{}'", model));
+                }
+            }
+
             // Add allowed tools if any
-            for tool in &allowed_tools {
+            for tool in &options.allowed_tools {
                 claude_cmd.push_str(&format!(" --allowedTools '{}'", tool));
             }
 
+            // Add custom instructions as system prompt if specified
+            if let Some(ref instructions) = options.custom_instructions {
+                if !instructions.is_empty() {
+                    // Escape single quotes in instructions
+                    let escaped = instructions.replace('\'', "'\\''");
+                    claude_cmd.push_str(&format!(" --system-prompt '{}'", escaped));
+                }
+            }
+
+            // Add MCP config if provided
+            if let Some(ref mcp_path) = mcp_config_path {
+                claude_cmd.push_str(&format!(" --mcp-config '{}'", mcp_path));
+            }
+
             // Use bash -lc to load login profile (ensures PATH includes claude)
             cmd.args(["-e", "bash", "-lc", &claude_cmd]);
 
@@ -212,6 +300,7 @@ impl WslBridge {
         }
         self.stdin = None;
         self.session_id = None;
+        self.mcp_config_file = None; // Temp file is automatically deleted when dropped
         emit_connection_status(app, ConnectionStatus::Disconnected);
     }