Flexible lanes load slower; purge at the previous filament's temperature

- flex_lanes.cfg: a 5 s poller sets SET_LONG_MOVE_SPEED to 50 mm/s (AFC's
  minimum) for lanes whose material is TPU/TPE/flex and back to the
  configured long_moves_speed otherwise; reapplied after a restart.
- BLOBIFIER_CHECKED: remembers the temperature of the filament in the
  nozzle (saved nozzle_last_temp). When it is more than flush_margin
  (10C) above the new filament's, the purge runs at that temperature and
  the nozzle cools back afterwards, so the leftover melts out (seen: ASA
  leftover with TPU loaded at 210C).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

macros/afc/purge_check.cfg

@@ -54,6 +54,14 @@ variable_start_counts: 0
 variable_start_e: 0.0
 variable_last_failed: False    # last check failed in enforce mode (read by _RESUME_PURGE_VERIFY)
 variable_ignore_missing_sensor: False  # set by PURGE_CHECK_IGNORE_SENSOR, cleared at print end
+# Hotter purge: the leftover of the previous filament (the piece below the
+# cutter) has to melt to be pushed out. When the filament that last went
+# through the nozzle (saved variable nozzle_last_temp) needs more than the
+# new one plus flush_margin, the purge runs at that temperature and the
+# nozzle cools back to the new filament's afterwards (seen: ASA leftover,
+# TPU loaded at 210C, purge only worked after heating by hand).
+variable_flush_margin: 10      # C; smaller differences purge at the new temperature
+variable_flush_restore: 0      # runtime: temperature to cool back to after a hot purge
 gcode:
 
 [gcode_macro BLOBIFIER_CHECKED]
@@ -77,6 +85,7 @@ gcode:
     # the purge too, so a bdwidth that does not see the movement cannot
     # pause the printer here; the pressure check judges the purge.
     {% set runout_off = has_bdw and (bdw_on or not cfg.motion_check) %}
+    _PURGE_FLUSH_HEAT
     {% if cfg.mode == "off" %}
         BLOBIFIER {rawparams}
     {% else %}
@@ -107,9 +116,41 @@ gcode:
             SET_FILAMENT_SENSOR SENSOR={bdw} ENABLE={runout_was}
         {% endif %}
     {% endif %}
+    _PURGE_FLUSH_DONE
 
 # Separate macros so the status is read when they run, not when
 # BLOBIFIER_CHECKED is rendered
+[gcode_macro _PURGE_FLUSH_HEAT]
+description: Helper for BLOBIFIER_CHECKED: heat to the previous filament's temperature when it is hotter than the new one
+gcode:
+    {% set cfg = printer["gcode_macro _PURGE_CHECK_CFG"] %}
+    {% set old = printer.save_variables.variables.nozzle_last_temp|default(0)|int %}
+    {% set new = printer.extruder.target|int %}
+    {% set top = printer.configfile.settings.extruder.max_temp|int - 15 %}
+    {% set hot = [old, top]|min %}
+    {% if new > 0 and hot > new + cfg.flush_margin %}
+      RESPOND MSG="Purge at {hot}C: the previous filament needs {old}C, back to {new}C after the purge"
+      SET_GCODE_VARIABLE MACRO=_PURGE_CHECK_CFG VARIABLE=flush_restore VALUE={new}
+      M104 S{hot}
+      TEMPERATURE_WAIT SENSOR=extruder MINIMUM={hot - 2}
+    {% else %}
+      SET_GCODE_VARIABLE MACRO=_PURGE_CHECK_CFG VARIABLE=flush_restore VALUE=0
+    {% endif %}
+
+[gcode_macro _PURGE_FLUSH_DONE]
+description: Helper for BLOBIFIER_CHECKED: cool back after a hot purge and remember the new filament's temperature
+gcode:
+    {% set cfg = printer["gcode_macro _PURGE_CHECK_CFG"] %}
+    {% set new = cfg.flush_restore|int if cfg.flush_restore|int > 0 else printer.extruder.target|int %}
+    {% if cfg.flush_restore|int > 0 %}
+      M104 S{new}
+      TEMPERATURE_WAIT SENSOR=extruder MAXIMUM={new + 3}
+      SET_GCODE_VARIABLE MACRO=_PURGE_CHECK_CFG VARIABLE=flush_restore VALUE=0
+    {% endif %}
+    {% if new > 0 %}
+      SAVE_VARIABLE VARIABLE=nozzle_last_temp VALUE={new}
+    {% endif %}
+
 [gcode_macro _PURGE_CHECK_START]
 gcode:
     SET_GCODE_VARIABLE MACRO=_PURGE_CHECK_CFG VARIABLE=start_counts VALUE={printer.bdwidth_status.total_move}