Purge and check before resuming after a PAUSE

_RESUME_PRINT purges 40 mm with BLOBIFIER_CHECKED (instead of the 2 mm
unretract), so the nozzle is primed, wiped and checked before going back
to the print. A failed purge check raises an error that aborts the whole
resume, AFC_RESUME's restore included, so the printer stays paused; the
next RESUME checks again. RESUME PURGE=0 skips the purge.

The purge check records a failure in _PURGE_CHECK_CFG.last_failed, since
its PAUSE has no effect while the printer is already paused.

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

CLAUDE.md

@@ -51,6 +51,9 @@ detection, `filament_error_sensitivity`), iHeater chamber heater.
   renames PAUSE/RESUME at startup and wraps them:
   `PAUSE -> AFC_PAUSE -> PAUSE -> PAUSE_BASE`,
   `RESUME -> AFC_RESUME -> RESUME -> HEAT_SOAK_RESUME -> _RESUME_PRINT -> RESUME_BASE`.
+  After a PAUSE, `_RESUME_PRINT` first purges with `BLOBIFIER_CHECKED`
+  (`_RESUME_PURGE`); a failed check raises an error, which aborts the whole
+  chain (AFC_RESUME's restore too), so the printer stays paused.
 - Only one `[save_variables]`, in `macros/save_variables.cfg`.
 - `PRINT_END` and `CANCEL_PRINT` share `_PRINT_CLEANUP` (heaters including
   `iHEATER_OFF`, fan, `M221 S100`, bdwidth off). Anything that must happen

README.md

@@ -21,7 +21,7 @@ everything below, grouped by topic. Comment out what you do not use there.
 | `blobifier_hw.cfg` | servo and bucket switch pins | — |
 | **print/** | | |
 | `print_start_end.cfg` | `PRINT_WARMUP`, `PRINT_START`, `PRINT_END` | Beacon, AFC, Blobifier, `HEAT_SOAK`, iHeater, bdwidth, bd_pressure PA macros |
-| `pause_resume.cfg` | `PAUSE`, `RESUME`, `CANCEL_PRINT`, `M600` (RESUME also handles a running `HEAT_SOAK`; CANCEL_PRINT runs the same cleanup as `PRINT_END`) | `heating/heat_soak.cfg`, `leds/` |
+| `pause_resume.cfg` | `PAUSE`, `RESUME`, `CANCEL_PRINT`, `M600` (RESUME also handles a running `HEAT_SOAK`, and after a PAUSE purges 40 mm with `BLOBIFIER_CHECKED` first: a failed check keeps the print paused, `RESUME PURGE=0` skips the purge; CANCEL_PRINT runs the same cleanup as `PRINT_END`) | `heating/heat_soak.cfg`, `leds/`, `blobifier/`, `afc/purge_check.cfg` |
 | `filament.cfg` | `LOAD_FILAMENT`, `UNLOAD_FILAMENT` | — |
 | `homing.cfg` | `HOME` | — |
 | `idle_timeout.cfg` | `[idle_timeout]`: heaters, chamber heater and motors off | iHeater macros |

macros/afc/purge_check.cfg

@@ -49,6 +49,7 @@ variable_pressure_min_ms: 5000 # placeholder: longest continuous pressure needed
 variable_bdwidth_warmup_ms: 15000
 variable_start_counts: 0
 variable_start_e: 0.0
+variable_last_failed: False    # last check failed in enforce mode (read by _RESUME_PURGE_VERIFY)
 gcode:
 
 [gcode_macro BLOBIFIER_CHECKED]
@@ -150,6 +151,7 @@ gcode:
         RESPOND MSG="PURGE_CHECK {lane}: {motion}; {press} -> {verdict}"
         {% if failed and cfg.mode == "enforce" %}
             RESPOND TYPE=error MSG="PURGE_CHECK: {lane} {failed|join(', ')} - check extruder and lane"
-            PAUSE
+            SET_GCODE_VARIABLE MACRO=_PURGE_CHECK_CFG VARIABLE=last_failed VALUE=True
+            PAUSE                       ; no effect while already paused (resume purge): see _RESUME_PURGE_VERIFY
         {% endif %}
     {% endif %}

macros/print/pause_resume.cfg

@@ -6,6 +6,10 @@
 #             -> RESUME_BASE, then AFC restores the saved position
 # RESUME is defined only here: heating/heat_soak.cfg used to define its own,
 # which replaced this one completely (no unretract, no fan restore).
+# After a PAUSE, _RESUME_PRINT purges into the Blobifier with the purge check
+# (BLOBIFIER_CHECKED, afc/purge_check.cfg) before going back to the print, so
+# the nozzle is primed and clean. If the check fails the resume stops with an
+# error and the printer stays paused. RESUME PURGE=0 resumes without the purge.
 
 # https://klipperscreen.readthedocs.io/en/latest/macros/#recommended
 [gcode_macro PAUSE]
@@ -33,10 +37,12 @@ gcode:
   HEAT_SOAK_RESUME ON_RESUME=_RESUME_PRINT {rawparams}
 
 [gcode_macro _RESUME_PRINT]
-description: Resume after PAUSE: unretract, restore the part fan, continue the print
+description: Resume after PAUSE: purge and check (or unretract), restore the part fan, continue the print
+variable_purge_length: 40      # mm purged before resuming after a PAUSE; 0 = only unretract
 gcode:
   {% set pause = printer["gcode_macro PAUSE"] %}
   {% set extrude = printer['gcode_macro _TOOLHEAD_PARK_PAUSE_CANCEL'].extrude %}
+  {% set purge = params.PURGE|default(purge_length)|float %}
   #### get VELOCITY parameter if specified ####
   {% if 'VELOCITY' in params|upper %}
     {% set get_params = ('VELOCITY=' + params.VELOCITY)  %}
@@ -47,9 +53,13 @@ gcode:
   # Only undo what PAUSE did; HEAT_SOAK pauses with PAUSE_BASE (no retract, no park)
   {% if pause.parked %}
     {% if printer.extruder.can_extrude|lower == 'true' %}
-      M83
-      G1 E{extrude} F2100
-      {% if printer.gcode_move.absolute_extrude |lower == 'true' %} M82 {% endif %}
+      {% if purge > 0 and 'gcode_macro BLOBIFIER' in printer %}
+        _RESUME_PURGE LENGTH={purge}     ; also replaces the unretract; stops here if the check fails
+      {% else %}
+        M83
+        G1 E{extrude} F2100
+        {% if printer.gcode_move.absolute_extrude |lower == 'true' %} M82 {% endif %}
+      {% endif %}
     {% else %}
       {action_respond_info("Extruder not hot enough")}
     {% endif %}
@@ -67,6 +77,27 @@ gcode:
   RESUME_BASE {get_params}
   _status_printing
 
+[gcode_macro _RESUME_PURGE]
+description: Purge LENGTH mm into the Blobifier (with the purge check if installed) before resuming
+gcode:
+  {% if 'gcode_macro BLOBIFIER_CHECKED' in printer %}
+    SET_GCODE_VARIABLE MACRO=_PURGE_CHECK_CFG VARIABLE=last_failed VALUE=False
+    BLOBIFIER_CHECKED PURGE_LENGTH={params.LENGTH}
+    _RESUME_PURGE_VERIFY
+  {% else %}
+    BLOBIFIER PURGE_LENGTH={params.LENGTH}
+  {% endif %}
+
+# Separate macro so the check result is read after the purge. Raising an
+# error aborts the whole RESUME (AFC_RESUME included): the printer stays
+# paused at the bucket and PAUSE.parked stays set, so the next RESUME purges
+# and checks again.
+[gcode_macro _RESUME_PURGE_VERIFY]
+gcode:
+  {% if printer["gcode_macro _PURGE_CHECK_CFG"].last_failed %}
+    {action_raise_error("Purge check failed: the print stays paused. Check the extruder and lane, then RESUME again (RESUME PURGE=0 resumes without purging).")}
+  {% endif %}
+
 [gcode_macro _TOOLHEAD_PARK_PAUSE_CANCEL]
 description: Helper: park toolhead used in PAUSE and CANCEL_PRINT
 variable_extrude: 2.0