Sensors previously only tracked alarm thresholds (alert_min/alert_max).
Missing the third piece of standard process control: the SETPOINT —
what the heater/chiller controls toward and what dashboards compare
against. Without it an operator can't tell whether 89°C is "on target"
or "barely still in spec".
Schema changes:
**fusion.plating.bath.parameter** (shop-wide default)
- New `target_value` field — the default setpoint for this parameter
across the shop (e.g. 87°C for ENP bath). Parallel to existing
target_min / target_max.
**fp.tank.sensor** (per-sensor override)
- New `target_value_override` — per-sensor override, zero = inherit
from parameter. Matches the existing override pattern for alert
thresholds so users can fine-tune per-tank without touching the
shop-wide spec.
- New `effective_target` / `effective_target_unit` computed — resolves
override → parameter default, converts to company-preferred unit.
- New `_get_setpoint()` helper for internal use.
**fp.tank.reading**
- New `deviation_from_target` — signed Δ from the sensor's effective
setpoint, in the company's preferred unit. Positive = above, negative
= below, zero if no setpoint defined.
- New `deviation_band` (selection: on/near/far/out/none) — coarse band
for fast visual scanning. `on` = within ±1° of target, `near` = ±3°,
`far` = beyond, `out` = actually out of the alarm band.
**Views**
- Sensor form: split the alerting panel into two groups — "Target
(setpoint)" on the left, "Alarm band" on the right. Makes the
distinction between "where we want to be" and "where we'd panic"
visually obvious.
- Reading list: new Δ + band columns, with decoration classes
(success/info/warning/danger) so the list reads at a glance.
- Tank form Sensors tab: inline setpoint + unit column.
Seeded: parameter "Bath Temperature (Hot Process)" now carries
target_value=87°C as a realistic ENP shop default. Sensors inherit
unless they set their own override.
Design decisions kept simple:
- Did NOT add a warning band (warn_min/warn_max). Two-tier model
(setpoint + alarm band) is enough for the pilot. Can add soft
warnings later as a separate commit if ops wants them.
- Did NOT auto-control heaters. Setpoint is stored as metadata only;
actual heater actuation via IoT is a future phase C project.
Verified: setpoint 87°C stored → displays 188.60°F on the live pilot
sensor (company pref = F). Each incoming reading correctly computes
signed deviation; bands colour the reading list appropriately.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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