perf: optimize SubagentLocator to reduce file I/O

[MintCollector]

Summary

• hasSubagents() / hasSubagentsSync(): Uses stat.size > 0 instead of reading entire file contents — avoids unnecessary I/O for existence checks
• subagentBelongsToSession(): Streams only the first line via readline.createInterface() instead of reading the entire file into memory

Addresses #95

Test plan

• All 653 tests pass
• Typecheck clean
• Lint clean
• Production build succeeds
• Verified createReadStream is available on FileSystemProvider interface

🤖 Generated with Claude Code

Summary by CodeRabbit

Release Notes

• Refactor
  • Optimized subagent discovery and session validation processes with more efficient file handling, resulting in faster and lighter resource utilization during initialization.

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the performance of the SubagentLocator service by optimizing file I/O operations. It transitions from reading entire file contents for simple checks to more efficient methods like checking file size metadata and streaming only necessary portions of files, thereby reducing resource consumption and improving responsiveness.

Highlights

• Performance Optimization for hasSubagents() and hasSubagentsSync(): The methods hasSubagents() and hasSubagentsSync() were optimized to reduce file I/O by checking stat.size > 0 instead of reading entire file contents to determine if a subagent file is non-empty.
• Efficient First-Line Reading in subagentBelongsToSession(): The subagentBelongsToSession() method was refactored to stream only the first line of a file using readline.createInterface() and createReadStream, thereby avoiding loading the entire file into memory for a single line check.

Changelog

• src/main/services/discovery/SubagentLocator.ts
  • Imported the readline module for stream processing.
  • Updated hasSubagents to use file size for existence checks.
  • Updated hasSubagentsSync to use file size for existence checks.
  • Refactored subagentBelongsToSession to stream the first line of a file.

Activity

• No human activity has been recorded on this pull request yet.

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[gemini-code-assist]

Code Review

The pull request optimizes file content checks in SubagentLocator.ts by using readline to stream only the first line for subagentBelongsToSession, avoiding full file reads. However, the change in hasSubagents and hasSubagentsSync to only check for a non-zero file size instead of non-whitespace content might unintentionally validate files with only whitespace. Additionally, the removal of certain JSDoc lines from hasSubagentsSync has reduced the clarity and completeness of its documentation.

I am having trouble creating individual review comments. Click here to see my feedback.

src/main/services/discovery/SubagentLocator.ts (60-62)

The previous implementation checked content.trim().length > 0 to ensure the file contained actual non-whitespace content. By removing this check and relying solely on stats.size > 0, a file consisting only of whitespace characters would now be considered a valid subagent file. This could be an unintended semantic change if "non-empty content" implies more than just a non-zero file size.

src/main/services/discovery/SubagentLocator.ts (79-81)

The removed lines from the JSDoc provided important context about the hasSubagentsSync method's behavior, specifically that it checks for session-specific subagent files and only in the NEW structure. Restoring these details would improve the clarity and completeness of the documentation.

  /**
   * Checks if a session has subagent files (session-specific only).
   * Only checks the NEW structure: {projectId}/{sessionId}/subagents/
   * Verifies that at least one subagent file has non-empty content.

[coderabbitai]

📝 Walkthrough

Walkthrough

Optimized file I/O operations in SubagentLocator by replacing full file reads with size-based validation checks and streaming-based first-line parsing for session association, reducing resource consumption while maintaining existing functionality.

Changes

Cohort / File(s)	Summary
File I/O Optimization src/main/services/discovery/SubagentLocator.ts	Replaced full file reads with size-based checks in hasSubagents and streaming-first-line parsing in subagentBelongsToSession for session validation; refactored file filtering logic to use streaming approach across OLD and NEW structure paths.

Suggested labels

feature request

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[coderabbitai]

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

src/main/services/discovery/SubagentLocator.ts (1)

77-82: ⚠️ Potential issue | 🔴 Critical

Critical syntax error: Missing JSDoc opening marker.

The JSDoc comment for hasSubagentsSync is missing the opening /** delimiter. Lines 77–82 start with * Verifies... without the required /** prefix, which breaks JSDoc parsing and will prevent TypeScript from recognizing the documentation block.

Fix

    return false;
  }

+/**
  * Verifies that at least one subagent file has non-empty content.
  *
  * `@param` projectId - The project ID
  * `@param` sessionId - The session ID
  * `@returns` true if subagents exist
  */
  hasSubagentsSync(projectId: string, sessionId: string): boolean {

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@src/main/services/discovery/SubagentLocator.ts` around lines 77 - 82, The
JSDoc block for hasSubagentsSync in SubagentLocator.ts is missing its opening
/** delimiter which breaks JSDoc parsing; fix by adding the opening /**
immediately before the existing lines that start with " * Verifies..." so the
comment becomes a valid JSDoc block for the hasSubagentsSync method (ensure the
comment directly precedes the hasSubagentsSync function declaration).

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Outside diff comments:
In `@src/main/services/discovery/SubagentLocator.ts`:
- Around line 77-82: The JSDoc block for hasSubagentsSync in SubagentLocator.ts
is missing its opening /** delimiter which breaks JSDoc parsing; fix by adding
the opening /** immediately before the existing lines that start with " *
Verifies..." so the comment becomes a valid JSDoc block for the hasSubagentsSync
method (ensure the comment directly precedes the hasSubagentsSync function
declaration).

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 04ad79f4-90b4-46e1-8d87-bfdaeab1c8e9

📥 Commits

Reviewing files that changed from the base of the PR and between f23c581 and 998c90e.

📒 Files selected for processing (1)

• src/main/services/discovery/SubagentLocator.ts