feat: replace pi-mono filesystem tools with native implementation

[shadowfax92]

Summary

• Removed @mariozechner/pi-coding-agent and @mariozechner/pi-agent-core dependencies that caused bun compile issues (tree traversal looking for package.json creates complexity during compilation)
• Reimplemented all 7 filesystem tools (read, write, edit, bash, grep, find, ls) using only Bun/Node.js built-in libraries
• No external binary dependencies (ripgrep, fd, etc.) — everything is pure TypeScript
• 107 new tests across 8 test files

Changes

Added (apps/server/src/tools/filesystem/)

File	Purpose
utils.ts	Shared utilities — truncation, path resolution, binary detection, walkFiles, toModelOutput
read.ts	Read files with line numbers, offset/limit pagination, image base64
write.ts	Create/overwrite files with auto parent directory creation
edit.ts	Exact string replacement with fuzzy whitespace-tolerant fallback
bash.ts	Shell command execution via Bun.spawn (sh on Unix, cmd on Windows)
grep.ts	Pure JS regex search across files (replaces ripgrep dependency)
find.ts	Glob-based file search using Bun.Glob (replaces fd dependency)
ls.ts	Directory listing with sizes, dirs-first sorting
build-toolset.ts	Assembles all tools into ai-sdk ToolSet

Modified

• apps/server/package.json — removed pi-mono dependencies
• apps/server/src/agent/tool-loop/ai-sdk-agent.ts — import changed to new build-toolset
• bun.lock — updated

Deleted

• apps/server/src/agent/tool-loop/filesystem-tools/pi-tool-adapter.ts

Test plan

• 107 new tests across 8 test files — all passing
• Server typecheck passes
• Lint passes (9 warnings — all expected as any in test helpers)
• Manual: verify agent tool loop works end-to-end with new tools
• Manual: verify bun run dist:server compile succeeds without pi-mono tree issues

🤖 Generated with Claude Code

[greptile-apps]

Greptile Summary

Replaced external @mariozechner/pi-mono dependencies with native Bun/Node.js implementations to fix bun compile issues. All 7 filesystem tools (read, write, edit, bash, grep, find, ls) reimplemented using only built-in libraries with no external binary dependencies.

Key changes:

• Implemented pure TypeScript replacements for all filesystem operations
• Added comprehensive error handling with try-catch blocks for file operations (including previous ENOENT issue)
• Preserved line ending detection and BOM handling for cross-platform compatibility
• Implemented whitespace-tolerant fuzzy matching in edit tool as fallback
• Added proper timeout and output truncation for bash tool
• Comprehensive test coverage with 107 tests across 8 test files

Technical improvements:

• walkFiles generator properly handles errors and skips ignored directories
• Binary file detection prevents reading non-text files in grep/find
• All tools properly resolve paths using resolve(cwd, path) for consistent behavior
• Metrics logging integrated for tool execution tracking

Confidence Score: 5/5

• This PR is safe to merge with minimal risk
• Score reflects well-structured implementation with comprehensive test coverage (107 tests), proper error handling throughout, no security issues introduced, and the previous stat() ENOENT issue has been properly addressed with try-catch blocks
• No files require special attention - all implementations follow best practices with proper error handling and comprehensive test coverage

Important Files Changed

Filename	Overview
apps/server/src/tools/filesystem/utils.ts	Added shared utilities for filesystem tools including truncation, path helpers, binary detection, and file walking
apps/server/src/tools/filesystem/read.ts	Implemented file reading with line numbers, pagination, and image base64 encoding support
apps/server/src/tools/filesystem/edit.ts	Implemented exact string replacement with whitespace-tolerant fallback and line ending preservation
apps/server/src/tools/filesystem/bash.ts	Implemented shell command execution via Bun.spawn with timeout support and output truncation
apps/server/src/tools/filesystem/grep.ts	Implemented pure JavaScript regex search across files with glob filtering and context lines
apps/server/src/agent/tool-loop/ai-sdk-agent.ts	Updated import path to use new native filesystem tools implementation
apps/server/package.json	Removed pi-mono dependencies that caused bun compile issues

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[AI Agent] -->|requests filesystem operation| B[ai-sdk-agent.ts]
    B -->|builds toolset| C[buildFilesystemToolSet]
    C -->|creates tools| D[Individual Tool Creators]
    
    D --> E[createReadTool]
    D --> F[createWriteTool]
    D --> G[createEditTool]
    D --> H[createBashTool]
    D --> I[createGrepTool]
    D --> J[createFindTool]
    D --> K[createLsTool]
    
    E -->|uses| L[utils.ts]
    F -->|uses| L
    G -->|uses| L
    H -->|uses| L
    I -->|uses| L
    J -->|uses| L
    K -->|uses| L
    
    L -->|provides| M[truncation]
    L -->|provides| N[walkFiles]
    L -->|provides| O[path helpers]
    L -->|provides| P[binary detection]
    
    E -->|reads via| Q[Node fs/promises]
    F -->|writes via| Q
    G -->|edits via| Q
    I -->|searches via| Q
    J -->|finds via| Q
    K -->|lists via| Q
    H -->|executes via| R[Bun.spawn]

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_{Last reviewed commit: 3a3ba57}

[greptile-apps]

_{21 files reviewed, 1 comment}

_{Edit Code Review Agent Settings | Greptile}

[greptile-apps]

wrap stat() in try-catch to handle ENOENT

Suggested change

	const pathStat = await stat(searchPath)
	let pathStat: Awaited<ReturnType<typeof stat>>
	try {
	pathStat = await stat(searchPath)
	} catch (err) {
	return {
	text: `Path not found: ${params.path || '.'}`,
	isError: true,
	}
	}

Prompt To Fix With AI

This is a comment left during a code review.
Path: apps/server/src/tools/filesystem/grep.ts
Line: 150

Comment:
wrap `stat()` in try-catch to handle ENOENT

```suggestion
        let pathStat: Awaited<ReturnType<typeof stat>>
        try {
          pathStat = await stat(searchPath)
        } catch (err) {
          return {
            text: `Path not found: ${params.path || '.'}`,
            isError: true,
          }
        }
```

How can I resolve this? If you propose a fix, please make it concise.