Add the dpatch depth-witness drill

live_fire_drills.py gains dpatch: two rows of small serpentine-filled
patches on scrap. Row A is CW at feeds that give relative doses from 1.0
to 0.25. Row B is density 100, 80, 60, 45, and 30 percent at F600. The
operator matches each row-B patch to the row-A patch of equal depth. That
reads the light fraction of a density off the material, next to the
prediction of the thermopile. The drill samples sysfs at 25 Hz, as pcurve
does, and writes a JSON record to the bench data directory.

Bench tool only, on the dev image; no catalog consequence.

scripts/bench/README.md

@@ -32,7 +32,7 @@ page's takeover does that; from a host, stop them first.
 | `gate_a_kernel_drills.py` | Kernel laser-safety drills (run on the board with forgectrl stopped so the pulse device is free): `K1` controlled-stop deceleration floor, `K2` resume waypoint honors the locked latch, `K3` a mid-ramp latch unlock never re-arms the FIRE drive. Software witnesses (`cnc/state`, `laser_enable`, `laser_on`, `laser_on_sampled`, interlock bit 3) plus the PSU-connector LASER_ON scope point; K3 refuses to run if HV reports good. |
 | `laser_stream_test.py` | Host-side laser pulse-stream emission harness: runs the native null-sink controller with `GFSINK_DUMP`, drives small laser jobs over TCP, and checks the dumped bytes against the kernel feeder contract (leading power byte, no back-to-back power bytes, FIRE only inside cutting moves, every stream ends FIRE-clear, no FIRE on a stepless gap, no FIRE leak across cycle churn, the rapids after an M5 executed at idle ship dark, and the next job in the same process fires at the level the previous one ended at). Runs in the grblHAL repo's CI. |
 | `laser_lifecycle_test.py` | Host-side operator-armed-window lifecycle harness (null-sink controller): arm once per job with M5/M3 persistence, the M2 close, sender-change re-consent, the disarm grace counting down in Hold, and arm refusal under a blocking cooling verdict. Runs in the grblHAL repo's CI. |
-| `live_fire_drills.py` | **LIVE LASER** drills, on the board (the bench page) or from a LAN host (`GF_HOST`): `live_fire_drills.py <drill> [S] [F]` - `witness` (emission witness, lid-IR peaks vs the ambient baseline, HV current, job-based disarm on M2), `hold` (disarm grace in Hold), `faultpos` (armed job refuses a stale origin after an underrun), `ircut` (lid-IR characterization cut at S/F), `pthresh` (laser power-threshold ladder: 13 constant-power rungs from 2 % to 30 % of full on scrap; the lowest rung that marks is the tube's striking threshold and reads directly as the `$35` value - requires `$35` = 0 for the run), `dladder` (density ladder at a chosen base period), `pcurve` (laser performance-curve ladder: one 100 mm line per level at 10 mm/s under M3, the laser off between rungs and a mid-ladder rung repeated at the end; reads `pic/hv_current` and the head thermopile `head/beam_detect_analog` (a scatter detector in the beam path upstream of the final mirror, so it sees the beam, not the material) from sysfs at ~25 Hz on the board, brackets each rung on the controller's Run/Idle states, and reports per rung the current with a clipped-at-1023 flag, the thermopile delta over its laser-off baseline and in-line drift, then the normalized curve, monotonicity, a line fit with its threshold intercept and the repeat-rung drift; JSON record with the raw trace in the bench data directory; rungs follow `laser_power_model`, a comma list overrides; a curve measurement wants `$35` = 0), `m5dark` (the rapids after an M5 ship dark: one 20 mm line at M3 S400, M5, dwell, rapid back, dwell, rapid forward; PASS when the 25 Hz current trace shows one discharge segment and reads dark after the M5 and `laser_on_sampled` never re-lights; the catalog's `laser.m5-rapid-dark` is its port), `expstop` (armed kill on the expected-stop path; needs the panel token - `GF_TOKEN`, or the board's token file) and `ctrlstart` (the separate controller restart after it). Every drill waits for the operator's physical arm press; eye protection, fire watch, extinguisher, and exhaust are mandatory. |
+| `live_fire_drills.py` | **LIVE LASER** drills, on the board (the bench page) or from a LAN host (`GF_HOST`): `live_fire_drills.py <drill> [S] [F]` - `witness` (emission witness, lid-IR peaks vs the ambient baseline, HV current, job-based disarm on M2), `hold` (disarm grace in Hold), `faultpos` (armed job refuses a stale origin after an underrun), `ircut` (lid-IR characterization cut at S/F), `pthresh` (laser power-threshold ladder: 13 constant-power rungs from 2 % to 30 % of full on scrap; the lowest rung that marks is the tube's striking threshold and reads directly as the `$35` value - requires `$35` = 0 for the run), `dladder` (density ladder at a chosen base period), `pcurve` (laser performance-curve ladder: one 100 mm line per level at 10 mm/s under M3, the laser off between rungs and a mid-ladder rung repeated at the end; reads `pic/hv_current` and the head thermopile `head/beam_detect_analog` (a scatter detector in the beam path upstream of the final mirror, so it sees the beam, not the material) from sysfs at ~25 Hz on the board, brackets each rung on the controller's Run/Idle states, and reports per rung the current with a clipped-at-1023 flag, the thermopile delta over its laser-off baseline and in-line drift, then the normalized curve, monotonicity, a line fit with its threshold intercept and the repeat-rung drift; JSON record with the raw trace in the bench data directory; rungs follow `laser_power_model`, a comma list overrides; a curve measurement wants `$35` = 0), `dpatch` (depth witness for the density curve: two rows of small serpentine-filled patches, row A CW at feeds giving relative doses 1.0 to 0.25, row B density 100/80/60/45/30 % at F600; the operator matches each row-B patch to the row-A patch of equal depth, which reads the density's light fraction off the material beside the thermopile's prediction; JSON record), `m5dark` (the rapids after an M5 ship dark: one 20 mm line at M3 S400, M5, dwell, rapid back, dwell, rapid forward; PASS when the 25 Hz current trace shows one discharge segment and reads dark after the M5 and `laser_on_sampled` never re-lights; the catalog's `laser.m5-rapid-dark` is its port), `expstop` (armed kill on the expected-stop path; needs the panel token - `GF_TOKEN`, or the board's token file) and `ctrlstart` (the separate controller restart after it). Every drill waits for the operator's physical arm press; eye protection, fire watch, extinguisher, and exhaust are mandatory. |
 | `pacing_test.py` | Protocol-loop pacing check (runs on the board, dry motion): idle and parked-in-Hold states are coarse-paced, active motion is tight-paced, and a feed-hold/resume mid-move preserves position with no feeder starve. |
 | `gfbench.py` | Not a tool: the helper the board/host tools share - `HOST`/`LOCAL` from `GF_HOST`, `board(cmd)` (local `sh -c` or ssh), the factory coolant conversion `degc()`, `data_path()` (`FORGETEST_BENCH_DATA` or next to the tool), forgectrl's HTTP API with the panel token, `setting(key)` (from forgectrl, or from `/data/forgefirm.conf` on the board while forgectrl is stopped). |
 | `fan_test.py` | Fan/coolant bench (board or host; controller running): snapshots fan PWMs/tachs/temps, drives M8 → cut fans, M9 → cooldown → idle, verifying via tach readbacks. |