Item 3: the failed-head-capture negative is proven; the fault note drops

A busy capture node made the real head-image path fail with the measure
laser armed; the laser ended at 0 and the camera engine recovered
(CAMPAIGN-LOG has the drill). The STATE_FAULT-recovery note leaves the
item by operator decision. What remains is the K-11 case, one bench
slot.

docs/BRINGUP.md

@@ -1115,11 +1115,10 @@ Open items only. Anything closed is in `CAMPAIGN-LOG.md`.
    reachable-mode reasoning and the factory fallback configuration are in
    the headers of kernel patches 0011-0013 (`meta-glowforge-bsp`,
    `recipes-kernel/linux/`).
-3. **Physical-evidence negatives still open.** A present head answering I²C
+3. **Physical-evidence negative still open.** A present head answering I²C
-   badly (the K-11 runtime case) and a failed head capture leaving the measure
+   badly (the K-11 runtime case) needs the head connected and the fault
-   laser off — both need the head connected and a fault injected. Opportunistic:
+   injected: flood the head's bus from userspace while the driver talks, one
-   `STATE_FAULT` recovery via `enable` the next time a DRV8825 fault line
+   bench slot.
-   actually trips.
 4. **Debug-kernel checks.** Module load/unload under `CONFIG_DEBUG_MUTEXES`
     and a forced `-EPROBE_DEFER` unwind still need a debug kernel build. Both
     drills cycle what the rail policy avoids: a module unload powers the 40 V

docs/CAMPAIGN-LOG.md

@@ -4940,6 +4940,21 @@ the directed set - panel-serves, snapshot, sensor-profile, h264-stream,
 frame-health, lid-privacy - green on the capped server with the bounded
 setup children.
 
+## 2026-08-31: a failed head capture leaves the measure laser off
+
+The physical-evidence negative, proven on the bench with the head
+connected. The injection: a `v4l2-ctl` streamer held the shared
+`ipu1_csi0` capture node busy, then the real `machine._head_image` path
+ran with `HCil` arming the measure laser (verified lit at 1023 on the
+real sysfs first). The busy pipeline refused the link change, the
+capture raised, and the path's finally left `head/measure_laser` at 0.
+forgectrl's camera engine recovered on its next request (snapshot 200,
+engine running). The `STATE_FAULT`-recovery note is dropped from the
+item by operator decision: the fault line has never tripped and the
+recovery lever is documented in the UAPI; nothing is held open for it.
+What remains of the item is the K-11 runtime case, one bench slot with
+the head's bus flooded from userspace.
+
 ## Superseded status notes
 
 ### Shared machine services — remaining polish, as listed 2026-08-13