midiviz: only the DAW dialect may be translated, and the pip still warns on both

Shipping the translation on raw_port was too wide. That flag means 'the picture
comes from the board, not the driver', which is true in DAW mode AND in custom
mode -- but only DAW mode has a fixed, known numbering we may rewrite. Custom
mode speaks whatever the user assigned, so translating it would have been a
second wrong picture with the opposite sign.

Not hypothetical: midiviz's reader was on 24:0 'LCXL3 1 MIDI In' at the moment
this was written (its aseqdump child, PPID 7049), i.e. exactly the port the
wide rule would have mistranslated.

So two flags for two questions. raw_port keeps the warning pip on any raw LCXL3
read; v3_dialect authorises the rewrite and only DAW satisfies it.

tools/bridge/midiviz.py

@@ -1124,6 +1124,7 @@ def build_widget(port_label: str, reader: "Reader | None", scale: float = 1.0,
             self.col_t = [0.0] * 9               # column 1..8 last-touch, for the glow
             self.stream: deque = deque(maxlen=256)   # bottom ribbon, newest right
             self.raw_port = False                # reading the board, untranslated
+            self.v3_dialect = False              # ...and in the one dialect we can fix
             self.drops: list[list] = []          # gutter rain
             self._drop_t: dict[int, float] = {}  # cc -> last token rained
             self.hist: deque = deque([0] * 64, maxlen=64)   # events per 100 ms
@@ -1247,6 +1248,18 @@ def build_widget(port_label: str, reader: "Reader | None", scale: float = 1.0,
             # front of it, so its raw port IS the right port, and a pip there
             # would be a false alarm on a board that is working.
             self.raw_port = ("LCXL3" in label) and ("ParVagues" not in label)
+            # TWO questions, deliberately not one flag. `raw_port` asks "is the
+            # picture coming from the board instead of the driver" and drives
+            # the warning pip -- true in DAW mode AND in custom mode, because in
+            # both the numbers are not guaranteed to be the corpus's.
+            # `v3_dialect` asks the narrower "may we translate", and only DAW
+            # mode may: that is the one dialect whose numbering is fixed and
+            # known. WATCH_PREFERENCE's third entry is the raw CUSTOM-mode port
+            # ('LCXL3 1 MIDI In'), which speaks user-assigned numbers -- and
+            # midiviz was reading exactly that port on 2026-09-23, so
+            # translating on `raw_port` would have been a second wrong picture
+            # with the opposite sign.
+            self.v3_dialect = ("DAW" in label) and ("ParVagues" not in label)
 
         # ── palette / fonts / geometry ─────────────────────────────────────
         def _build_palette(self):
@@ -1499,7 +1512,7 @@ def build_widget(port_label: str, reader: "Reader | None", scale: float = 1.0,
                 # nothing, and E5-E8 lit E1-E4 for as long as the driver was
                 # down. A viewer that owns the translation is right either way,
                 # so the picture no longer depends on another process running.
-                if self.raw_port:
+                if self.v3_dialect:
                     cc = grid.V3_TO_V2.get(cc, cc)
                 cell = grid.CC_TO_CELL.get(cc)
                 if cell is not None:

tools/bridge/tests/test_surface_state.py

@@ -553,7 +553,7 @@ def test_the_publisher_omits_a_fader_it_has_never_observed(tmp_path, monkeypatch
 def test_a_raw_port_move_lands_in_the_cell_the_finger_touched(tmp_path):
     mv, w = _offscreen_widget(MV, tmp_path / "absent.json")
     try:
-        w.raw_port = True
+        w.v3_dialect = True
         # C1 on the hardware sends v3 CC 29. Untranslated that is row C's *v2*
         # number for a different cell -- the exact mislanding PLN saw as
         # "it only moves on abc".
@@ -571,7 +571,7 @@ def test_a_raw_port_move_lands_in_the_cell_the_finger_touched(tmp_path):
 def test_the_translated_port_is_left_exactly_alone(tmp_path):
     mv, w = _offscreen_widget(MV, tmp_path / "absent.json")
     try:
-        w.raw_port = False                    # the driver is up; numbers are ours
+        w.v3_dialect = False                  # the driver is up; numbers are ours
         cc = grid.ROW_CCS["C"][0]
         w.ingest(_cc_event(cc, 77))
         assert cc in w.cc and w.cc[cc][0] == 77
@@ -584,7 +584,7 @@ def test_row_d_is_no_longer_rain_on_the_raw_port(tmp_path):
     # all -- so every fader move used to spawn a raindrop and light no cell.
     mv, w = _offscreen_widget(MV, tmp_path / "absent.json")
     try:
-        w.raw_port = True
+        w.v3_dialect = True
         for v3 in grid.V3_ROWS["D"]:
             w.ingest(_cc_event(v3, 64))
         lit = {grid.V3_TO_V2[c] for c in grid.V3_ROWS["D"]}
@@ -592,3 +592,28 @@ def test_row_d_is_no_longer_rain_on_the_raw_port(tmp_path):
         assert all(grid.CC_TO_CELL[c][0] == "D" for c in lit)
     finally:
         w.close()
+
+
+@pytest.mark.parametrize("label,translate", [
+    ("128:0 · ParVagues LCXL3", False),  # already ours; translating twice is a shift
+    ("24:1 · LCXL3 1 DAW", True),        # the ONE dialect with a fixed known map
+    ("24:0 · LCXL3 1 MIDI", False),      # CUSTOM mode: user-assigned, not v3
+    ("20:0 · Launch Control XL", False), # a v2 board speaks v2 already
+    ("14:0 · Midi Through", False),
+    ("no MIDI source found", False),
+])
+def test_only_the_daw_dialect_is_ever_translated(label, translate):
+    """Narrower than the pip rule on purpose. The pip asks "is this the board?"
+    and custom mode answers yes; this asks "do we know its numbering?" and only
+    DAW mode does. midiviz was reading 24:0 when this was written, so the wide
+    rule would have mistranslated a live stream."""
+    assert (("DAW" in label) and ("ParVagues" not in label)) is translate
+
+
+def test_both_flags_exist_and_the_tick_sets_each_one():
+    src = open(MV.__file__).read()
+    assert 'self.raw_port = ("LCXL3" in label)' in src, "the pip rule moved"
+    assert 'self.v3_dialect = ("DAW" in label)' in src, "the translate rule moved"
+    assert "if self.v3_dialect:" in src, (
+        "ingest no longer translates on the narrow flag — if this became "
+        "raw_port again, custom mode would be mistranslated")