kicad-zone-resistance/docs/release-notes/v1.4.0.md

PDN mode, a full configuration-file workflow and a reworked dialog - all opt-in: classic runs behave exactly as in 1.3.0 (the analytic test suite runs unchanged against the same solver paths).

PDN mode - multiple supplies and loads on one net:

• Instead of one driven terminal pair, a run can now model a power rail: any number of supply points, each a Thevenin source with a configurable output resistance (and optionally its own open-circuit voltage), plus any number of loads, each drawing its own prescribed current. The solve runs in absolute volts and reports the IR-drop map, each supply's delivered current (the Thevenin split - an outcome, not an input), and each load's mean and worst-case contact voltage, alongside the usual per-layer dissipation, |J| maps and per-via currents.
• The summary carries a source-sink pair table: for every supply x load pair, the effective COPPER resistance between the two contacts (operating-point independent, source R_out excluded; one extra linear solve per terminal, deferred-corrected on the adaptive grid too) plus the copper loss attributed to the pair by proportional sharing - an attribution convention, but it sums exactly to the total copper dissipation, never crosses a copper gap, and pairs without a common copper path report "no path". The same table is also rendered as a figure (5_source_sink_pairs.png) alongside the field maps; terminals are keyed by their unique labels (no positional tags), and both outputs note each terminal's component hint and comment - the summary in the supplies/loads tables, the figure in a terminals legend underneath.
• The consistency check generalizes: source power = copper loss + output-resistance loss + load power (Tellegen), verified on every run. Both the uniform-reference and the adaptive grid support PDN mode; geometry dumps embed the terminal set (schema v8) and re-solve offline via standalone.py with no extra flags. Older dumps load unchanged.

The dialog editor - PDN runs need no JSON at all:

• The dialog gained a Mode selector: Classic (unchanged - and simply called that; a "two-terminal" label would read like a 2-contact cap, but classic terminals can bundle many contact parts) or PDN. In PDN mode, rectangles on User.1 are supply terminals and rectangles on User.2 are load terminals - the same marker layers as classic, but each rectangle is its OWN terminal instead of being merged into one V+/V- contact. Two editable tables - one for supplies, one for loads, each titled with the marker layer its rectangles come from - assign each load its current draw and each supply its output resistance (plus an optional open-circuit voltage; empty = the V-nominal field). PDN is selectable whenever both layers carry at least one rectangle; otherwise the radio is disabled with the reason shown, and a classic-mode failure (nothing selected, no marker pair) no longer kills the launch when PDN rectangles exist - the dialog opens in the mode that works.
• A text item placed inside a rectangle names the terminal; unnamed rectangles get automatic names (S1../L1.., stable reading order).
• A read-only Component column identifies each row: the footprint whose pad intersects the contact area (e.g. "U5"), or "near U5" when nothing touches it. Purely spatial - it names where the terminal sits, it plays no electrical role.
• Every terminal row picks its contacted copper in a Layer combo, like the classic contact scopes: "All selected layers" (a rectangle's natural bolted-lug scope) or one specific layer. The choice is saved as the terminal-level "contact" key.
• Every row has an Active checkbox: unchecking it disregards the terminal (no solve, value cells may stay blank) WITHOUT deleting it
  • the row is saved as "active": false and can be re-enabled later. A free-text Comment column is saved with each terminal ("comment" key). Both are editable in config-backed setups too.
• The tables show only the rectangles that actually sit on the selected net: switching the net swaps the visible set, the totals line counts the hidden rows, and hidden rows take no part in the run - not validated, not solved. Saving keeps them anyway: every row lands in the config file, off-net ones as "active": false with their values and comments intact, and config-backed runs apply the same per-net filter so archived terminals are skipped, never fatal.
• The terminal tables are height-resizable: each sizes itself to its rows, a drag handle between the two redistributes space, and enlarging the dialog grows them. In PDN mode the dialog opens at ~60% of the screen height (capped at 85%/90% of the screen; the KiCad window itself is not reachable through the IPC API, so the screen is the reference). The whole form scrolls when it outgrows the screen (the error line and the buttons always stay visible at the bottom).
• Numbers understand SI suffixes: 50m = 0.05, 4.7k = 4700, 2M = 2e6 (case separates milli from mega). This works in every dialog number field (R_out, V_oc, I draw, V nominal, test current, cell size, thresholds), in the config file (any number may be a string: "r_out_ohm": "50m"), and in the CLI's --current / --cell-um / --v-nominal. The frequency field keeps its own grammar (142k, 1.5M - a lone m means MHz there, as before).

Bonded terminals - a package's total current with a free per-pin split:

• A terminal (config key "bonded": true; in the editor, simply give several rectangles the same name) shorts all its contacts into one lug, the way a multi-pin package joins its pins with internal metal: the TOTAL current stays prescribed, but which contact carries how much becomes a solve outcome instead of the default per-cell area share. Works for loads and supplies (a bonded supply is an equipotential lug with its whole output resistance in series), on both grids, and the reported per-part currents are the computed boundary fluxes. A bonded load may even span disconnected copper sheets - the bond is the connection.

Configuration file - the run, fully specified next to the board:

• A JSON config next to the board file can specify a complete run: every dialog field, the classic terminals by board reference (skipping the selection / marker-rectangle step), the select physics constants that previously required editing config.py (resistivity, copper thickness, via plating), the marker layer names - or the whole PDN terminal set. Precedence is simple: config.py defaults < config file < dialog edits; the file pre-fills the dialog, what the dialog shows is what runs.
• Terminals are written by board reference: "U7" (all pads of a footprint on the net), "U7.3" (one pad), "rect:NAME" (a rectangle named by a text item placed inside it - searched on User.3, User.1 and User.2, so names must be unique across the marker layers), explicit rectangles or nearest-via coordinates.
• Configs can be kept side by side as "fill_res_config..json": the config named "default" loads automatically (plain "fill_res_config.json" is its legacy spelling, and a board-specific ".fill_res_config.json" wins over both), and the Load config... button in the dialog pulls in any other config for this run - the dialog re-opens seeded entirely from the picked file. Save config... asks for the target file name each time (pre-filled with the loaded config; ".json" appended when omitted), so writing back and branching a variant are both one click; a name outside the auto-load set prints a Load-config reminder.
• Save config... works in both modes: classic saves write the run parameters and contact scopes, PDN saves write the whole terminal set - named rectangles as live "rect:NAME" references (they follow the rectangle wherever it moves), unnamed ones as frozen rect_mm coordinates, so label your rectangles if the layout is still moving. Full-line // comments and "_"-prefixed keys are allowed; invalid files stop the run with the offending key path instead of silently running defaults; unknown keys warn (typo guard).
• A config never pins anything. Its mode is only the STARTING mode (a classic-mode file may carry a terminals section and vice versa), the net stays switchable, values / layer scopes / active flags / comments are editable per run and written back on save (part references are preserved verbatim; part-level contacts keep winning over the terminal scope), and a classic save over a PDN config keeps the whole terminals section - it just flips the starting mode. A broken terminal reference disables PDN mode with the reason shown instead of killing the launch.
• A config-backed set is open-ended: any marker rectangle the file does not reference yet appears as a NEW terminal row (a note under the tables counts them) and Save config... appends it to the file. A rectangle named after an existing rect:NAME terminal instead joins that terminal as another contact part at resolve time. A label colliding with an unrelated terminal name is skipped with a note; colliding auto names are renumbered.
• standalone.py gained --config (run-parameter defaults under the explicit flags) and --v-nominal.