Install cs---engine-shed-2, and stop the tests snapshotting INSTALLED

CLAUDE.md

@@ -109,8 +109,9 @@ bench check that covers it instead. Do not leave it silently untested.
 
 ## Current state (2026-08)
 
-The IO node is **deployed and working end to end** (#1, #2, #3). Both Goods Shed sensors
-publish contract readings that the orchestrator trusts, and the block follows them.
+The IO node is **deployed and working end to end** (#1, #2, #3). Installed: `cs---engine-shed-2`
+(a `bazauto/block-detection` channel) and `ir---goods-shed`. Goods Shed has lost its detector,
+so that block can go occupied but not clear (`docs/pin-allocation.md`).
 
 Point position feedback on board 3 (`0x22`) is **built but publishes nothing yet** (#15): the
 expander answers on the bus but `POINTS_INSTALLED` is empty, and **the feedback source is

README.md

@@ -77,8 +77,8 @@ means it is running. The codes are in `docs/startup-and-status-led.md`.
 
 ## Status
 
-The IO node is deployed and working end to end. Both Goods Shed sensors, one current-sensing
-and one IR, publish contract readings that the orchestrator trusts.
+The IO node is deployed and working end to end. Two sensors publish contract readings: the
+Engine Shed 2 current detector and the Goods Shed IR beam.
 
 Still open:
 

docs/pin-allocation.md

@@ -164,20 +164,26 @@ wire it to its allocated pin, add its id to the installed list, deploy.
 
 ## Currently installed
 
-Two, both on the **Goods Shed** block:
+Two, on different blocks (2026-09-25):
 
 | Board | Pin | Port | Chip pin | `sensorId` |
 |---|---|---|---|---|
-| 1 (`0x20`) | 8 | GPB0 | 1 | `cs---goods-shed` |
+| 1 (`0x20`) | 7 | GPA7 | 28 | `cs---engine-shed-2` |
 | 2 (`0x21`) | 8 | GPB0 | 1 | `ir---goods-shed` |
 
+`cs---goods-shed` came out of `INSTALLED` when its LM-iD.1 was removed. Goods Shed now has
+only its beam, and an `ir_position` `clear` is a no-op downstream, so **that block can go
+occupied but can never clear** until a detector is back on board 1 pin 8. The orchestrator
+also stops hearing `cs---goods-shed`, marks it untrusted, and treats the block as `unknown`
+(occupied). Both are the fail-safe direction.
+
 **No points.** Board 3 is fitted and answers on the bus, but no feedback source has been
 chosen or wired, so `POINTS_INSTALLED` is empty and nothing is published on any `point/*/reading`. Bring points up
 **one at a time**: every point fault kind Safe-Stops the whole layout, including a fault on a
 point no route holds, so flipping all six to `positionFeedback: "required"` at once produces a
 layout that halts on the first flaky contact with five other unproven points to rule out.
 
-Two things follow from this being the pair brought up first, both of which paid off:
+Goods Shed's two sensors were the pair brought up first, and two things followed from that, both of which paid off:
 
 - **Goods Shed is the only block with both a CS and an IR sensor installed**, so the bring-up
   exercised the occupancy derivation rather than one sensor in isolation. That proved its

src/apps/io-node/config.py

@@ -111,13 +111,14 @@
      "active_low": WAVESHARE_IR_ACTIVE_LOW},
 )
 
-# Physically wired, and therefore the only sensors published. Both on Goods Shed, which
-# is the one block with both a detector and a beam — so the bring-up exercises the
-# occupancy derivation rather than one sensor in isolation. Every board 1 entry above is
+# Physically wired, and therefore the only sensors published. The Goods Shed detector
+# was taken out of service 2026-09-25 when its LM-iD.1 was removed; its beam stays. A
+# block whose only live sensor is IR can go occupied but never clear, because an
+# `ir_position` `clear` is a no-op downstream. Every board 1 entry above is
 # already on the bazauto/block-detection polarity, so bringing another detector online is
 # only a matter of adding its id here.
 INSTALLED = (
-    "cs---goods-shed",
+    "cs---engine-shed-2",
     "ir---goods-shed",
 )
 

tests/test_io_node_config.py

@@ -27,18 +27,21 @@ def test_the_layout_id_is_real():
     assert config.LAYOUT_ID == "c4e587aa-478d-46ab-a1df-9dd8359fc040"
 
 
-def test_both_installed_sensors_are_the_goods_shed_pair():
-    """The one block with both a detector and a beam, so the bring-up exercises the
-    occupancy derivation rather than one sensor in isolation."""
-    assert set(config.INSTALLED) == {"cs---goods-shed", "ir---goods-shed"}
+def test_every_installed_sensor_is_on_the_board_its_prefix_names():
+    """`cs---` is current sensing on board 1, `ir---` is IR on board 2. A sensor on the
+    wrong board would be read with the other device's polarity, upside down.
 
+    Deliberately not a snapshot of INSTALLED: bringing a sensor online is a config change
+    and should not also need a test edit."""
+    board_for = {"cs---": config.EXPANDER_CS, "ir---": config.EXPANDER_IR}
+    for entry in select_installed(config.SENSORS, config.INSTALLED):
+        prefix = entry["sensor_id"][:len("cs---")]
+        assert prefix in board_for, entry["sensor_id"]
+        assert entry["expander"] == board_for[prefix], entry["sensor_id"]
 
-def test_installed_sensors_resolve_to_the_documented_pins():
-    """docs/pin-allocation.md: both on pin 8, board 1 for CS and board 2 for IR."""
-    by_id = {e["sensor_id"]: e for e in select_installed(config.SENSORS, config.INSTALLED)}
 
-    assert (by_id["cs---goods-shed"]["expander"], by_id["cs---goods-shed"]["pin"]) == (0x20, 8)
-    assert (by_id["ir---goods-shed"]["expander"], by_id["ir---goods-shed"]["pin"]) == (0x21, 8)
+def test_installed_sensors_are_not_duplicated():
+    assert len(set(config.INSTALLED)) == len(config.INSTALLED)
 
 
 def test_pin_n_is_the_same_block_on_both_boards():
@@ -55,12 +58,14 @@ def test_pin_n_is_the_same_block_on_both_boards():
 
 
 def test_the_installed_sensors_have_their_devices_polarity():
-    """Goods Shed's detector is the bazauto/block-detection board, occupied reads 1; its
-    beam is a Waveshare IR switch to ground, triggered reads 0."""
-    by_id = {e["sensor_id"]: e for e in select_installed(config.SENSORS, config.INSTALLED)}
-
-    assert by_id["cs---goods-shed"]["active_low"] is config.BAZAUTO_BD_ACTIVE_LOW is False
-    assert by_id["ir---goods-shed"]["active_low"] is config.WAVESHARE_IR_ACTIVE_LOW is True
+    """Detectors are the bazauto/block-detection board, occupied reads 1; beams are
+    Waveshare IR switches to ground, triggered reads 0."""
+    expected = {config.EXPANDER_CS: config.BAZAUTO_BD_ACTIVE_LOW,
+                config.EXPANDER_IR: config.WAVESHARE_IR_ACTIVE_LOW}
+    assert config.BAZAUTO_BD_ACTIVE_LOW is False
+    assert config.WAVESHARE_IR_ACTIVE_LOW is True
+    for entry in select_installed(config.SENSORS, config.INSTALLED):
+        assert entry["active_low"] is expected[entry["expander"]], entry["sensor_id"]
 
 
 def test_every_current_sensor_uses_the_bazauto_detector_polarity():