🤖 Add niceness parameter to executeBash for process priority control (#162)

Add optional `niceness` parameter to the `executeBash` IPC call for
controlling process priority. This parameter is only available at the
IPC level and is not exposed to agents in tool descriptions.

## Changes

- **Add niceness parameter to IPC interface**: Added optional `niceness`
parameter to `executeBash` options (accepts -20 to 19, where lower =
higher priority)
- **Wire through stack**: Parameter flows from IPC → ipcMain handler →
bash tool → process spawn
- **Bash tool implementation**: When niceness is specified, commands are
wrapped with `nice -n <value>`
- **Frontend git operations**: Set all git-related executeBash calls to
use niceness 19 (lowest priority) to prevent background operations from
interfering with user interactions
- **Auto-dependency installation**: Added `ensure-deps` Makefile target
that automatically runs `bun install` if `node_modules` doesn't exist

## Technical Details

When niceness is provided, the bash tool wraps commands like:
```bash
nice -n 19 bash -c "original command"
```

All git operations in GitStatusContext and GitStatusIndicator now run at
lowest priority:
- Git fetch (30s timeout) 
- Git status checks (5s timeout)
- Git diff operations (5s timeout)

_Generated with `cmux`_

Author: ammar-agent

Makefile

@@ -24,6 +24,7 @@
 .PHONY: test test-unit test-integration test-watch test-coverage test-e2e
 .PHONY: dist dist-mac dist-win dist-linux
 .PHONY: docs docs-build docs-watch
+.PHONY: ensure-deps
 
 # Prettier patterns for formatting
 PRETTIER_PATTERNS := 'src/**/*.{ts,tsx,json}' 'tests/**/*.{ts,json}' 'docs/**/*.{md,mdx}' '*.{json,md}'
@@ -32,6 +33,13 @@ TS_SOURCES := $(shell find src -type f \( -name '*.ts' -o -name '*.tsx' \))
 # Default target
 all: build
 
+# Ensure dependencies are installed
+ensure-deps:
+	@if [ ! -d "node_modules" ]; then \
+		echo "node_modules not found, running bun install..."; \
+		bun install; \
+	fi
+
 ## Help
 help: ## Show this help message
 	@echo 'Usage: make [target]'
@@ -40,7 +48,7 @@ help: ## Show this help message
 	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "  \033[36m%-20s\033[0m %s\n", $$1, $$2}'
 
 ## Development
-dev: build-main ## Start development server (Vite + TypeScript watcher)
+dev: ensure-deps build-main ## Start development server (Vite + TypeScript watcher)
 	@bun x concurrently -k \
 		"bun x concurrently \"bun x tsc -w -p tsconfig.main.json\" \"bun x tsc-alias -w -p tsconfig.main.json\"" \
 		"vite"
@@ -49,16 +57,16 @@ start: build-main build-preload ## Build and start Electron app
 	@bun x electron --remote-debugging-port=9222 .
 
 ## Build targets (can run in parallel)
-build: src/version.ts build-renderer build-main build-preload ## Build all targets
+build: ensure-deps src/version.ts build-renderer build-main build-preload ## Build all targets
 
-build-main: dist/main.js ## Build main process
+build-main: ensure-deps dist/main.js ## Build main process
 
 dist/main.js: src/version.ts tsconfig.main.json tsconfig.json $(TS_SOURCES)
 	@echo "Building main process..."
 	@NODE_ENV=production bun x tsc -p tsconfig.main.json
 	@NODE_ENV=production bun x tsc-alias -p tsconfig.main.json
 
-build-preload: dist/preload.js ## Build preload script
+build-preload: ensure-deps dist/preload.js ## Build preload script
 
 dist/preload.js: src/preload.ts $(TS_SOURCES)
 	@echo "Building preload script..."
@@ -69,7 +77,7 @@ dist/preload.js: src/preload.ts $(TS_SOURCES)
 		--sourcemap=inline \
 		--outfile=dist/preload.js
 
-build-renderer: src/version.ts ## Build renderer process
+build-renderer: ensure-deps src/version.ts ## Build renderer process
 	@echo "Building renderer..."
 	@bun x vite build
 

src/components/GitStatusIndicator.tsx

@@ -324,6 +324,7 @@ ${getDirtyFiles}
       const result = await window.api.workspace.executeBash(workspaceId, script, {
         timeout_secs: 5,
         max_lines: 100,
+        niceness: 19, // Lowest priority - don't interfere with user operations
       });
 
       if (!result.success) {

src/contexts/GitStatusContext.tsx

@@ -79,6 +79,7 @@ export function GitStatusProvider({ workspaceMetadata, children }: GitStatusProv
       try {
         const result = await window.api.workspace.executeBash(workspaceId, GIT_FETCH_SCRIPT, {
           timeout_secs: 30,
+          niceness: 19, // Lowest priority - don't interfere with user operations
         });
 
         if (!result.success) {
@@ -204,6 +205,7 @@ export function GitStatusProvider({ workspaceMetadata, children }: GitStatusProv
                 GIT_STATUS_SCRIPT,
                 {
                   timeout_secs: 5,
+                  niceness: 19, // Lowest priority - don't interfere with user operations
                 }
               );
 

src/services/ipcMain.ts

@@ -757,7 +757,7 @@ export class IpcMain {
         _event,
         workspaceId: string,
         script: string,
-        options?: { timeout_secs?: number; max_lines?: number; stdin?: string }
+        options?: { timeout_secs?: number; max_lines?: number; stdin?: string; niceness?: number }
       ) => {
         try {
           // Get workspace metadata to find workspacePath
@@ -778,6 +778,7 @@ export class IpcMain {
           const bashTool = createBashTool({
             cwd: workspacePath,
             secrets: secretsToRecord(projectSecrets),
+            niceness: options?.niceness,
           });
 
           // Execute the script with provided options

src/services/tools/bash.ts

@@ -94,8 +94,16 @@ export const createBashTool: ToolFactory = (config: ToolConfiguration) => {
       }
 
       // Create the process with `using` for automatic cleanup
+      // If niceness is specified, wrap the command with nice
+      const finalScript =
+        config.niceness !== undefined
+          ? `nice -n ${config.niceness} bash -c ${JSON.stringify(script)}`
+          : script;
+      const finalCommand =
+        config.niceness !== undefined ? ["bash", "-c", finalScript] : ["bash", "-c", script];
+
       using childProcess = new DisposableProcess(
-        spawn("bash", ["-c", script], {
+        spawn(finalCommand[0], finalCommand.slice(1), {
           cwd: config.cwd,
           env: {
             ...process.env,

src/types/ipc.ts

@@ -192,7 +192,7 @@ export interface IPCApi {
     executeBash(
       workspaceId: string,
       script: string,
-      options?: { timeout_secs?: number; max_lines?: number; stdin?: string }
+      options?: { timeout_secs?: number; max_lines?: number; stdin?: string; niceness?: number }
     ): Promise<Result<BashToolResult, string>>;
     openTerminal(workspacePath: string): Promise<void>;
 

src/utils/tools/tools.ts

@@ -18,6 +18,8 @@ export interface ToolConfiguration {
   cwd: string;
   /** Environment secrets to inject (optional) */
   secrets?: Record<string, string>;
+  /** Process niceness level (optional, -20 to 19, lower = higher priority) */
+  niceness?: number;
 }
 
 /**