From 1a57e57583ca71ef083e6d65b0477782bf177127 Mon Sep 17 00:00:00 2001
From: TPTBusiness <tpt.requests@pm.me>
Date: Sat, 18 Apr 2026 08:05:49 +0200
Subject: [PATCH] fix(optuna): fix inverted parameter range in Stage 2/3 when
 signal_bias is negative
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`_sample_fine_params` and `_sample_very_fine_params` used `max(0.0, center - half_width)`
for all float parameters. When signal_bias=-0.95 (a valid Stage-1 result), this
produced low=0.0, high=-0.75 — an inverted range that causes Optuna to raise
ValueError on every trial, silently caught and returned as -inf.

Fix:
- Extract `_suggest_bounded()` helper with per-parameter floor values
- signal_bias floor is -1.0 (not 0.0 — it is a signed parameter)
- Guard against high <= low for both float and int suggestions
- Elevate trial failure logs from debug to warning so future regressions are visible

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>