# no_diagnostic_noise — v1

**Why this iteration:** Lifted verbatim from `conductor/code_styleguides/python.md` §8 (lines 68-70) + `AGENTS.md` "Session-Learned Anti-Patterns" §5. This is the baseline encoding — the imperative-bullet style currently in production.
Future variants will test alternative encodings (rationale-first, before/after) against this baseline.

**Source:** `conductor/code_styleguides/python.md:68-70 + AGENTS.md:"Session-Learned Anti-Patterns" §5`

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From `conductor/code_styleguides/python.md` §8 "AI-Agent Specific Conventions":
- **No diagnostic noise in production code (Added 2026-06-09).** `sys.stderr.write(f"[XYZ_DIAG] ...")` lines added to `src/*.py` for one-time debugging are technical debt the moment they ship. The project's production code should not contain `[XYZ_DIAG]` markers, `print(...debug...)` calls, or any other ad-hoc debug instrumentation. The right place for diagnostic output during a one-time investigation is `tests/artifacts/<test_name>.diag.log` (a log file) or a standalone `/tmp/diag_<name>.py` script. If you must instrument a production function for a single test run, the diag lines are part of the same atomic commit as the fix — they do not live uncommitted in the working tree. If you "revert everything," that means the diag lines are also reverted.

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From `AGENTS.md` "No Diagnostic Noise in Production (kill it)":
- Diagnostic stderr goes to a log file (`tests/artifacts/<test_name>.diag.log`) or to a temporary diagnostic script (`/tmp/diag_rag.py`), NOT to `src/*.py`. If you absolutely must instrument a production function for a single test run, the diag lines are part of the same atomic commit as the fix — they do not live uncommitted in the working tree. If you "revert everything," that means the diag lines are also reverted.