MT5 Log Reader

Read MetaTrader 5 log files directly to access Print() output from indicators, scripts, and expert advisors without requiring manual Experts pane inspection.

Purpose

Implement "Option 3" dual logging pattern:

Print() - MT5 log files (human-readable via Experts pane)
CSV files - Structured data (programmatic analysis)

Claude Code CLI can autonomously read both outputs without user intervention.

When to Use This Skill

Use this skill when:

Validating MT5 indicator/script execution
Checking compilation or runtime errors
Analyzing Print() debug output
Verifying unit test results (Test_PatternDetector, Test_ArrowManager)
User mentions checking "Experts pane" manually

Log File Location

MT5 logs are stored at:

$MQL5_ROOT/Program Files/MetaTrader 5/MQL5/Logs/YYYYMMDD.log

File Format:

Encoding: UTF-16LE (Little Endian)
Structure: Tab-separated fields (timestamp, source, message)
Size: Grows throughout day (typically 10-100KB)

Instructions

1. Construct today's log path

/usr/bin/env bash << 'SKILL_SCRIPT_EOF'
# Determine current date
TODAY=$(date +"%Y%m%d")

# Build absolute path
LOG_FILE="$MQL5_ROOT/Program Files/MetaTrader 5/MQL5/Logs/${TODAY}.log"
SKILL_SCRIPT_EOF

2. Read the entire log file

Use Read tool:

File path: Absolute path from step 1
The file contains all Print() statements from MT5 indicators/scripts
UTF-16LE encoding is automatically handled by Read tool

3. Search for specific content (optional)

Use Grep to filter entries:

Pattern: indicator name, "error", "test.*passed", etc.
Path: Log file path from step 1
Output mode: "content" with -n (line numbers)
Context: -A 5 for 5 lines after matches

4. Analyze recent entries (optional)

Use Bash with tail for latest output:

tail -n 50 "$LOG_FILE"

Common Validation Patterns

Check unit test results

Search for test pass/fail indicators:

Pattern: test.*passed|test.*failed|Tests Passed|Tests Failed|ALL TESTS PASSED
Output mode: content
Context: -B 2 -A 2

Find compilation errors

Pattern: error|ERROR|warning|WARNING|failed to create
Output mode: content
Context: -A 3

Monitor specific indicator

Pattern: CCI Rising Test|PatternDetector|ArrowManager
Output mode: content
Context: -A 2

View initialization messages

Pattern: OnInit|initialization|Initialization complete|Phase \d+
Output mode: content

Examples

Example 1: Validate unit test completion

Input: User compiled Test_PatternDetector.mq5
Action:
  1. Read today's log file
  2. Grep for "Test.*PatternDetector|Tests Passed|Tests Failed"
  3. Report results (e.g., "17 tests passed, 0 failed")
Output: Test status without user checking Experts pane

Example 2: Check for runtime errors

Input: User reports indicator not working
Action:
  1. Read today's log file
  2. Grep for "ERROR|error|failed" with -A 3 context
  3. Analyze error messages
Output: Specific error details and line numbers

Example 3: Verify Phase 2 arrow creation

Input: User asks "did the test arrow get created?"
Action:
  1. Read today's log file
  2. Grep for "Phase 2|Test arrow created|Failed to create"
  3. Check for success/failure messages
Output: Arrow creation status with timestamp

Security Considerations

Log files may contain sensitive trading data (symbol names, account info)
Restricted to Read, Bash, Grep tools only (no network access via WebFetch)
Do not expose absolute paths unnecessarily in user-facing output
Filter sensitive information when reporting results
No file modification operations allowed

Integration with Dual Logging

This skill enables programmatic access to one half of the dual logging pattern:

MT5 Log Files (this skill) - Human-readable Print() output
CSV Files (CSVLogger.mqh) - Structured audit trails for validation

Both are accessible without user intervention:

MT5 logs: Read via this skill
CSV files: Read directly via Read tool or validate_export.py

Validation Checklist

When using this skill:

Log file exists for today's date
File size > 0 (not empty)
Contains expected indicator/script output
Timestamps match execution time
Error messages (if any) are actionable
Test results (if applicable) show pass/fail counts

References

MT5 file locations: docs/guides/MT5_FILE_LOCATIONS.md
Dual logging implementation: docs/plans/cci-rising-pattern-marker.yaml Phase 3-4
CSVLogger library: Program Files/MetaTrader 5/MQL5/Indicators/Custom/Development/CCINeutrality/lib/CSVLogger.mqh

Troubleshooting

Issue	Cause	Solution
Log file not found	Wrong date or path	Verify YYYYMMDD.log format and MQL5_ROOT env var
Empty log file	MT5 not running or no output	Ensure MT5 is running and Print() is being called
Encoding errors	UTF-16LE not handled	Read tool handles encoding automatically
Missing test results	Test not executed	Compile and run test script in MT5 first
Grep finds nothing	Wrong pattern	Use case-insensitive (-i) or broader pattern
Old log data	Log rotation	Each day creates new YYYYMMDD.log file
Path contains spaces	Unquoted path variable	Quote paths: "$LOG_FILE"
Sensitive data exposed	Trading info in logs	Filter sensitive fields when reporting to user

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