[FIX] tab4: fix heatmap zero-display for tiny values, remove unused imports and redundant session state inits

tabs/tab4_optimization.py

@@ -2,11 +2,9 @@ from collections import defaultdict
 import datetime
 import io
 import json
-import re
 import unicodedata
 import zipfile
 import openpyxl
-import numpy as np
 import pandas as pd
 import streamlit as st
 import plotly.express as px
@@ -317,9 +315,10 @@ def panel_load_from_json_or_csv():
         # Restore custom resource batches if present in the scenario
         st.session_state.custom_resources = data.get("custom_resources", [])
         st.session_state.enabled_methods = data.get("enabled_methods", {})
-        # Reset auto_disabled_methods so tab1's re-enable logic starts from a
-        # clean slate matching the loaded scenario (avoids stale entries that
-        # would prevent or incorrectly trigger re-enable on the next tab1 visit).
+        # Reset auto_disabled_methods so refresh_active_methods (app.py's shared
+        # init) starts from a clean slate matching the loaded scenario (avoids
+        # stale entries that would prevent or incorrectly trigger re-enable on
+        # the next render).
         st.session_state.auto_disabled_methods = set()
         clear_widget_keys()
         for _m, _c in st.session_state.constraints.items():
@@ -684,14 +683,33 @@ def show_heatmap(df_result, resource_caps, method_costs, custom_resources=None,
     df_heat = pd.DataFrame(matrix_pct, index=y_labels, columns=available)
     df_exact = pd.DataFrame(matrix_exact, index=y_labels, columns=available)
 
+    # A genuine but tiny usage (e.g. 0.03%) rounds to "0.0" at 1 decimal,
+    # visually indistinguishable from a true zero. Below 0.05 show the exact
+    # value instead (enough decimals to reveal it, trailing zeros stripped)
+    # so a real (if small) contribution never looks like "not used at all".
+    def _fmt_pct(v):
+        if v <= 0:
+            return "0"
+        if v < 0.1:
+            s = f"{v:.4f}".rstrip("0").rstrip(".")
+            return s if s else "0"
+        return f"{v:.1f}"
+
+    text_matrix = [[_fmt_pct(v) for v in row] for row in matrix_pct]
+
     fig = px.imshow(
-        df_heat, color_continuous_scale=PLOTLY_HEATMAP_SCALE, text_auto=".1f",
+        df_heat, color_continuous_scale=PLOTLY_HEATMAP_SCALE,
         labels=dict(x="Resource", y="Method", color="% Used"),
     )
     matrix_exact_fmt = [[f"{v:.10g}" for v in row] for row in matrix_exact]
+    pct_and_exact = [
+        [[text_matrix[i][j], matrix_exact_fmt[i][j]] for j in range(len(available))]
+        for i in range(len(y_labels))
+    ]
     fig.update_traces(
-        customdata=matrix_exact_fmt,
-        hovertemplate="<b>%{y}</b><br>%{x}<br>% of cap: %{z:.1f}%<br>Exact: %{customdata}<extra></extra>",
+        text=text_matrix, texttemplate="%{text}",
+        customdata=pct_and_exact,
+        hovertemplate="<b>%{y}</b><br>%{x}<br>% of cap: %{customdata[0]}%<br>Exact: %{customdata[1]}<extra></extra>",
     )
     n_rows = len(df_heat.index)
     n_cols = len(df_heat.columns)
@@ -721,7 +739,7 @@ def show_heatmap(df_result, resource_caps, method_costs, custom_resources=None,
         df_pct_display = df_export_pct.copy()
         for col in df_pct_display.columns:
             if col != "Method":
-                df_pct_display[col] = df_pct_display[col].map(lambda x: f"{x:.1f}%")
+                df_pct_display[col] = df_pct_display[col].map(lambda x: f"{_fmt_pct(x)}%")
         st.dataframe(df_pct_display, width='stretch', hide_index=True)
 
     register_chart_data("Resource usage heatmap (% of cap)", df_export_pct)
@@ -811,7 +829,6 @@ def show_resource_balance(latest):
     st.markdown('<p class="crra-sub-heading">Resource balance: used vs available</p>', unsafe_allow_html=True)
     resource_caps = latest["resource_caps"]
     used_total = latest["resource_used_total"]
-    remaining = latest["resource_remaining"]
 
     resource_to_group = get_resource_to_group()
     # Custom batch names: their amounts come from resource_caps (expanded batches
@@ -1352,15 +1369,14 @@ def render_tab():
         unsafe_allow_html=True
     )
 
+    # resource_caps / constraints / costs / scenarios / enabled_methods are
+    # already guaranteed by app.py's shared init (runs before any tab renders)
+    # — only these two upload-widget counters are tab4-specific.
     for key, default in [
-        ("resource_caps", {}), ("constraints", {}),
-        ("costs", {}), ("scenarios", {}),
         ("excel_uploader_key", 0),
         ("scenario_uploader_key", 0)
     ]:
         st.session_state.setdefault(key, default)
-    if "enabled_methods" not in st.session_state:
-        st.session_state.enabled_methods = {}
 
     tab_run, tab_results, tab_resources, tab_bottleneck, tab_export, tab_reset = st.tabs([
         "▶️ Run",