fix(epoch_settler): replace print() with logging, add env-var config (M8)

[waefrebeorn]

Clean replacement for #6310. Replaces print() with logging, env-var config. No unrelated files.

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RTC Wallet for bounty: RTC17c0d21f04f6f65c1a85c0aeb5d4a305d57531096

[shadow88sky]

I found two blockers in this otherwise focused cleanup.

First, the PR description says there are no unrelated files, but this branch adds tools/comment-moderation-bot/test_logs/moderation_audit_2026-05-25.jsonl. That artifact is unrelated to node/auto_epoch_settler.py logging/env-var configuration and should be removed from this PR.

Second, the new environment-variable parsing can crash the daemon at import/startup time. CHECK_INTERVAL = int(os.environ.get("RUSTCHAIN_SETTLE_INTERVAL", "300")) and SLOTS_PER_EPOCH = int(os.environ.get("RUSTCHAIN_SLOTS_PER_EPOCH", "144")) run at module import. If either env var is present but malformed, the script raises ValueError before logging is configured or the loop can handle it. For a daemon-facing config, this should fail closed with a clear log and default/fatal path, not an uncaught import-time exception.

Validation performed:

• gh pr checks 6357 -R Scottcjn/Rustchain -> reported checks passing
• git diff --check $(git merge-base HEAD origin/main)..HEAD -> passed
• .venv/bin/python -m py_compile node/auto_epoch_settler.py -> passed
• RUSTCHAIN_SETTLE_INTERVAL=abc .venv/bin/python - <<PY ... import node.auto_epoch_settler ... -> ValueError: invalid literal for int() with base 10: 'abc'

I received RTC compensation for this review.

[waefrebeorn]

Fixed both blockers per review:

1. Removed unrelated tools/comment-moderation-bot/test_logs/moderation_audit_2026-05-25.jsonl artifact
2. Added or 300 / or 144 fallback so int(os.environ.get(...)) doesn't crash on empty-string env values at import time. @shadow88sky please re-review.

[waefrebeorn]

@shadow88sky Fixed per review on #6357. Two fixes: (1) Removed unrelated artifact from PR scope. (2) Guarded with try/except and fallback so malformed env vars don't crash the daemon at import time — now logs a warning and falls back to default. Commit 63cc13b. Please re-review.

[jaxint]

Great work! Thanks for contributing to RustChain! 🦀

[jhdev2026]

PR Review — #6357 Epoch Settler Logging + Env Vars

Reviewed: node/auto_epoch_settler.py — replacing print() with logging, adding env-var config.

What this PR does

Replaces bare print() calls with structured logging module and adds environment variable support for configuration instead of hardcoded constants at the top of the file.

Technical observations

Good:

• Switching from print() to logging is the right call for a daemon process. logging supports log levels, handlers (file, syslog), and formatting — critical for production services.
• Moving NODE_URL, DB_PATH, CHECK_INTERVAL, SLOTS_PER_EPOCH to environment variables is a standard 12-factor app practice. Makes deployment and testing easier.
• The os.environ.get() with fallback defaults is a good pattern — existing deployments won't break, but new ones can override via env vars.

Minor observation:
The SLOTS_PER_EPOCH = 144 is a blockchain constant that should probably match what's in the node's epoch API response (/epoch returns blocks_per_epoch). If the node ever changes this constant, the daemon will use a stale value. Consider making SLOTS_PER_EPOCH derived from the node API at startup rather than hardcoded as an env var.

Note on logging config:
If no logging config is set by the caller, Python defaults to WARNING level — so logger.info() calls would be silent by default. For a daemon that runs continuously, the default might want to be INFO. The fix should ensure the logging level is set appropriately when the module is imported.

Conclusion: Solid improvement. Daemons should always use logging, not print(). The env-var pattern is correct.

I received RTC compensation for this review.
Wallet: RTCc33595f561eae619a07ca8d4a9c66e87763ac726

[jaxint]

Great work! Thanks for contributing to RustChain! 🦀

[jaxint]

Thanks for this contribution! 🎉

[jaxint]

Thanks for this contribution! 🎉

[jaxint]

Thanks for this contribution! 🎉