Remove ANSI Color Codes from File Logging

[josecelano]

Summary

Remove ANSI color codes from log files when using compact and pretty formats, or implement independent format control for file vs stderr outputs. Currently, both formats write ANSI escape sequences to log files, making them harder to parse with standard text tools (grep, awk, editors).

This is a follow-up refinement to #3, discovered during PR review.

Problem

When using --log-format compact or --log-format pretty with file logging, ANSI escape codes are written to files:

$ hexdump -C /tmp/logs/log.txt | head -5
00000000  1b 5b 32 6d 32 30 32 35  2d 31 30 2d 31 35 54 31  |.[2m2025-10-15T1|
00000010  35 3a 30 39 3a 33 31 2e  34 39 39 36 35 32 5a 1b  |5:09:31.499652Z.|
00000020  5b 30 6d 20 1b 5b 33 32  6d 20 49 4e 46 4f 1b 5b  |[0m .[32m INFO.[|

Why problematic:

• Hard to parse with grep/awk/sed
• 15-20% file size overhead
• Issues with plain text editors
• Log aggregation tools may not handle correctly

JSON format works correctly (no ANSI codes).

Recommended Solution

Option A: Independent format control (recommended)

• Add --log-file-format and --log-stderr-format arguments
• Users choose exact format for each destination
• Automatically disable ANSI for file writers, enable for stderr
• Most flexible, no assumptions about user needs

Option B: Auto-detect destination (simpler but less flexible)

• Force no-ANSI when writing to files
• Keep same format for both outputs

Implementation

See full specification in docs/issues/remove-ansi-codes-from-file-logging.md

Key changes:

1. Update CLI arguments in src/app.rs
2. Modify logging layer in src/logging.rs to add .with_ansi(false) for files
3. Update tests to verify ANSI presence/absence
4. Update documentation

Estimated effort: 5-6 hours

Related

• Parent: Scaffolding for main app - 8/9 tasks complete (89%) #2 (Scaffolding for main app)
• Related: Setup logging for production CLI #3 (Setup logging for production CLI)
• Documentation: docs/issues/remove-ansi-codes-from-file-logging.md