Retract at print end, undo it at print start

Klipper's G10 retracts only once until a G11, and nothing sends G11 on
this printer: the G10 in PRINT_WARMUP used up the retract, so PRINT_END
never retracted and the nozzle leaked while cooling down.

- _NOZZLE_RETRACT retracts and remembers the amount in the saved
  variable nozzle_retract (survives restarts, capped at 15 mm).
  PRINT_END retracts 5 mm, PRINT_WARMUP 2 mm, CANCEL_PRINT 5 mm plus the
  park/PAUSE retract.
- _NOZZLE_UNRETRACT in PRINT_START pushes it back over the bucket before
  the wipe.

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

CLAUDE.md

@@ -54,6 +54,10 @@ check runs with `motion_check: False`), iHeater chamber heater.
   `iHEATER_OFF`, fan, `M221 S100`, bdwidth off). Anything that must happen
   at the end of every print goes there. `RESTORE_GCODE_STATE` restores the
   flow (M221), so reset flow after it, not before.
+- Do not use `G10`/`G11` in macros: Klipper's `G10` retracts only once until
+  a `G11`, and nothing on this printer sends `G11`. Use `_NOZZLE_RETRACT`
+  (remembered in the saved variable `nozzle_retract`); `PRINT_START` undoes
+  it over the bucket with `_NOZZLE_UNRETRACT`.
 - Inside `gcode:` use `;` for comments on G-code lines; `#` lines are
   stripped by the config parser.
 - After a refactor run `python tools/effective_config.py HEAD` and check that

macros/print/pause_resume.cfg

@@ -109,6 +109,8 @@ description: Cancel the actual running print
 rename_existing: CANCEL_PRINT_BASE_KLIPPERSCREEN
 variable_park: True
 gcode:
+  {% set pause = printer["gcode_macro PAUSE"] %}
+  {% set park_retract = printer['gcode_macro _TOOLHEAD_PARK_PAUSE_CANCEL'].extrude %}
   ## Move head and retract only if not already in the pause state and park set to true
 
   {% if printer.pause_resume.is_paused|lower == 'false' and park|lower == 'true'%}
@@ -117,6 +119,15 @@ gcode:
 
   STOP_HEAT_SOAK
   CANCEL_PRINT_BASE_KLIPPERSCREEN
+  # Same end-of-print retract as PRINT_END (skipped if the nozzle is already cold);
+  # EXTRA: the park retract of PAUSE or of the park above, so PRINT_START undoes it too
+  {% if printer.pause_resume.is_paused %}
+    _NOZZLE_RETRACT EXTRA={park_retract if pause.parked else 0}
+  {% elif park and printer.extruder.can_extrude %}
+    _NOZZLE_RETRACT EXTRA={park_retract}
+  {% else %}
+    _NOZZLE_RETRACT
+  {% endif %}
   # Same cleanup as PRINT_END: heaters incl. chamber heater, fan, flow, bdwidth
   _PRINT_CLEANUP
   SET_GCODE_VARIABLE MACRO=PAUSE VARIABLE=parked VALUE=False

macros/print/print_start_end.cfg

@@ -79,7 +79,7 @@ gcode:
     T{initial_tool} #PURGE_LENGTH=100 #Load Initial Tool
     M104 S{target_extruder}                    ; set extruder to print temp
     M109 S{target_extruder}                    ; wait for extruder temp
-    G10 ; retract
+    _NOZZLE_RETRACT LENGTH=2                   ; no oozing while waiting; PRINT_START pushes it back
     
     M104 S150       ; set nozzle temp to 150
     M109 S150       ; wait until nozzle reaches 150  ; wait until nozzle reaches 0
@@ -165,6 +165,8 @@ gcode:
     _status_heating
     M104 S{target_extruder}                    ; set extruder to print temp
     M109 S{target_extruder}                    ; wait for extruder temp
+    BLOBIFIER_PARK                             ; over the bucket, then undo the retracts
+    _NOZZLE_UNRETRACT                          ; of PRINT_WARMUP and the previous PRINT_END
     
     #                             ; needs fine tuning, long meltzones require more
     # SET_GCODE_OFFSET Z_ADJUST={OFFSET}  ; apply optional material squish via slicer
@@ -222,8 +224,7 @@ gcode:
 
     M400                           ; wait for buffer to clear
     G92 E0                         ; zero the extruder
-    # G1 E-0.5 F1800                 ; retract filament
-    G10 ; retract
+    _NOZZLE_RETRACT                ; so the nozzle does not leak while cooling down
     
     TURN_OFF_HEATERS
     iHEATER_OFF   ; Turns off the chamber heater
@@ -254,6 +255,48 @@ gcode:
     BED_MESH_CLEAR
     SET_SKEW CLEAR=1
 
+# Retract/unretract that is remembered across prints and restarts.
+# Klipper's G10 only retracts once until a G11, and nothing sends G11 here,
+# so G10 in PRINT_WARMUP used up the retract and PRINT_END's G10 did nothing.
+# _NOZZLE_RETRACT adds to the saved variable nozzle_retract, _NOZZLE_UNRETRACT
+# extrudes that amount again (over the bucket, in PRINT_START) and clears it.
+[gcode_macro _NOZZLE_RETRACT]
+description: Retract LENGTH mm (default variable_length) and remember it for _NOZZLE_UNRETRACT; EXTRA=mm already retracted elsewhere, only remembered
+variable_length: 5.0           # end-of-print retract; more stops leaking, too much can jam (PLA/heat creep)
+variable_max_total: 15.0       # never remember more than this in total
+gcode:
+    {% set length = params.LENGTH|default(length)|float %}
+    {% set extra = params.EXTRA|default(0)|float %}
+    {% set done = printer.save_variables.variables.nozzle_retract|default(0)|float %}
+    {% set length = [length, max_total - done - extra]|min %}
+    {% if length > 0 and printer.extruder.can_extrude %}
+        SAVE_GCODE_STATE NAME=_nozzle_retract
+        M83
+        G1 E-{length} F1800
+        RESTORE_GCODE_STATE NAME=_nozzle_retract
+    {% else %}
+        {% set length = 0 %}
+    {% endif %}
+    {% if length + extra > 0 %}
+        SAVE_VARIABLE VARIABLE=nozzle_retract VALUE={[done + extra + length, max_total]|min}
+    {% endif %}
+
+[gcode_macro _NOZZLE_UNRETRACT]
+description: Extrude what _NOZZLE_RETRACT retracted (call over the bucket, nozzle hot)
+gcode:
+    {% set done = printer.save_variables.variables.nozzle_retract|default(0)|float %}
+    {% if done > 0 %}
+        {% if printer.extruder.can_extrude %}
+            SAVE_GCODE_STATE NAME=_nozzle_unretract
+            M83
+            G1 E{done} F300
+            RESTORE_GCODE_STATE NAME=_nozzle_unretract
+            SAVE_VARIABLE VARIABLE=nozzle_retract VALUE=0
+        {% else %}
+            RESPOND TYPE=error MSG="_NOZZLE_UNRETRACT: extruder too cold, {done} mm still retracted"
+        {% endif %}
+    {% endif %}
+
 [delayed_gcode _delayed_motors_off]
 gcode:
   M84