feat(python): chamfer, arrays, explode, join, break, stretch and lengthen wrappers

Each is written against the prompt sequence observed in the exploration harness
and checked for exact geometry in the real-IPC audit. HATCH is left to
create_entity because its command needs an interactive boundary pick.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

plugins/opencad-python/PLUGIN.md

@@ -281,6 +281,13 @@ M.fillet(first, second, radius=2)           # radius 0 squares the corner
 M.move([a, b], (0, 0, 0), (5, 5, 0)); M.copy([a], base, target)
 M.rotate([a], base, 90); M.scale([a], base, 2)
 M.mirror([a], p1, p2, erase_source=False); M.erase([a])
+M.chamfer(first, second, 2, 3)              # distance 2 along first, 3 along second
+M.array_rect([a], rows=2, columns=3, row_spacing=10, column_spacing=20)
+M.array_polar([a], center, count=4, angle=360)   # counts include the original
+M.explode([polyline]); M.join([line1, line2])
+M.break_entity(line, first_point, second_point)
+M.stretch(corner1, corner2, base, target)   # crossing window, then the displacement
+M.lengthen(line, 5, at=near_the_end)        # delta; negative shortens
 ```
 
 Each step returns an outcome dict: `status` (`completed` or `waiting_input`),
@@ -292,7 +299,8 @@ Each step returns an outcome dict: `status` (`completed` or `waiting_input`),
 also closing any editor or dialog it opened. `doc.command` cancels and raises when
 the line leaves a prompt open.
 
-Selection-based tools (`move`, `copy`, `rotate`, `scale`, `mirror`, `erase`) select
+Selection-based tools (`move`, `copy`, `rotate`, `scale`, `mirror`, `erase`, the arrays,
+`explode` and `join`) select
 the entities you pass first, so the command skips its own selection prompt. Pick
 points default to the middle of a line, arc or circle; give `at=` for anything else.
 `trim` and `extend` cut or extend against every entity in the drawing. Each command is
@@ -304,7 +312,9 @@ line names a command that could end the session or re-enter Python: `QUIT`,
 `RECOVER`, `SCRIPT`, `RUNSCRIPT` and any `PY_*`. Commands run on the active
 document only. Commands that need an interactive surface a script cannot fill
 (the rich-text editor, a file dialog) report it in `blocked_by` and are cancelled.
-`ocs.command_step(kind, options)` is the raw single step behind all of this.
+Hatching has no wrapper: create it with `create_entity("Hatch", ...)`, because the
+HATCH command needs an interactive boundary pick. `ocs.command_step(kind, options)`
+is the raw single step behind all of this.
 
 ### Historical command-replay experiment (not in the default build)
 

plugins/opencad-python/src/document_model.py

@@ -751,6 +751,76 @@ class _Modify:
             lambda c: c.token("Y" if erase_source else "N"),
         ], entities)
 
+    def chamfer(self, first, second, distance1, distance2=None, at1=None, at2=None):
+        """Cut the corner between two lines; `distance1` is measured along `first`
+        and `distance2` (default the same) along `second`. Returns the new line."""
+        if distance2 is None:
+            distance2 = distance1
+        result = self._run("CHAMFER", [
+            lambda c: c.token("D"),
+            lambda c: c.text(distance1),
+            lambda c: c.text(distance2),
+            lambda c: c.entity(first, self._at(first, at1)),
+            lambda c: c.entity(second, self._at(second, at2)),
+        ])
+        if not result:
+            raise RuntimeError("CHAMFER produced nothing")
+        return result[0]
+
+    def array_rect(self, entities, rows, columns, row_spacing, column_spacing):
+        """Rectangular array of the entities: `rows` by `columns` copies counting
+        the original, spaced by `row_spacing` and `column_spacing`. Returns the copies."""
+        return self._run("ARRAYRECT", [
+            lambda c: c.text(rows),
+            lambda c: c.text(columns),
+            lambda c: c.text(row_spacing),
+            lambda c: c.text(column_spacing),
+        ], entities)
+
+    def array_polar(self, entities, center, count, angle=360):
+        """Polar array about `center`: `count` items counting the original, spread
+        over `angle` degrees. Returns the copies."""
+        return self._run("ARRAYPOLAR", [
+            lambda c: c.point(center),
+            lambda c: c.text(count),
+            lambda c: c.text(angle),
+        ], entities)
+
+    def explode(self, entities):
+        """Break polylines, blocks and similar entities into their parts; returns the parts."""
+        return self._run("EXPLODE", [], entities)
+
+    def join(self, entities):
+        """Join end-to-end lines, arcs and polylines into one entity; returns it."""
+        return self._run("JOIN", [], entities)
+
+    def break_entity(self, entity, first, second):
+        """Remove the part of `entity` between two points on it; returns the new piece."""
+        return self._run("BREAK", [
+            lambda c: c.entity(entity, first),
+            lambda c: c.point(second),
+        ])
+
+    def stretch(self, corner1, corner2, base, target):
+        """Stretch whatever the crossing window (two opposite corners) catches, moving
+        `base` to `target`; entities fully inside move, ones crossing the edge stretch."""
+        self._run("STRETCH", [
+            lambda c: c.point(corner1),
+            lambda c: c.point(corner2),
+            lambda c: c.enter(),
+            lambda c: c.point(base),
+            lambda c: c.point(target),
+        ])
+
+    def lengthen(self, entity, delta, at=None):
+        """Lengthen (or, negative, shorten) `entity` by `delta` at the end nearest `at`."""
+        self._run("LENGTHEN", [
+            lambda c: c.token("DE"),
+            lambda c: c.text(delta),
+            lambda c: c.entity(entity, self._at(entity, at)),
+            lambda c: c.enter(),
+        ])
+
     def erase(self, entities):
         before = len(list(ocs.entity_handles()))
         self._select(entities)

plugins/opencad-python/tests/test_document_model.py

@@ -58,7 +58,7 @@ class DocumentModelTests(unittest.TestCase):
         outcome = {"status": "completed", "blocked_by": None, "command": "", "prompt": "", "accepts": [],
                    "options": [], "entities": 0, "added": 0, "unconsumed": [], "error": None}
         outcome.update(self.step_outcome.get(kind, {}))
-        if kind == "enter":
+        if kind in ("enter", "entity"):
             new = max(self.records) + 1
             self.records[new] = {"handle": new, "kind": "Line", "layer": "0", "_editable": True}
         return outcome
@@ -98,6 +98,22 @@ class DocumentModelTests(unittest.TestCase):
         entity_step = [c for c in self.calls if c[0] == "step" and c[1] == "entity"][0]
         self.assertEqual(entity_step[2]["point"], [1, 0, 5.0])
 
+    def test_more_modify_wrappers(self):
+        self.step_outcome = {}
+        self.doc.modify.chamfer(1, 2, 2, 3, at1=(0, 0, 0), at2=(1, 1, 0))
+        texts = [c[2]["text"] for c in self.calls if c[0] == "step" and c[1] == "text"]
+        self.assertEqual(texts, ["2", "3"])
+        self.calls.clear()
+        self.doc.modify.chamfer(1, 2, 4, at1=(0, 0, 0), at2=(1, 1, 0))
+        texts = [c[2]["text"] for c in self.calls if c[0] == "step" and c[1] == "text"]
+        self.assertEqual(texts, ["4", "4"])
+        self.calls.clear()
+        self.doc.modify.array_rect([1], 2, 3, 10, 20)
+        self.assertEqual([c[2]["text"] for c in self.calls if c[0] == "step" and c[1] == "text"], ["2", "3", "10", "20"])
+        self.calls.clear()
+        self.doc.modify.stretch((0, 0), (1, 1), (0, 0), (5, 0))
+        self.assertEqual([c[1] for c in self.calls if c[0] == "step"], ["start", "point", "point", "enter", "point", "point"])
+
     def test_batch_edit_and_rollback(self):
         line = self.doc.entities[1]
         self.assertEqual(line.start, (1, 2, 3))