Loading files
This file is pinned to the selected release. Download the original to open it in your design tool.
97c6f2bbeThis file is pinned to the selected release. Download the original to open it in your design tool.
"""Net-level v1<->v2 schematic diff (SPEC §3.6).
The hard correctness requirement (risk #10): a schematic diff that keys on the
*display name* of a net is useless on real boards, because both Altium and KiCad
hand out coordinate-derived auto-names (``N$1234``) that churn on every edit, and
designers rename nets freely. This module therefore matches:
* **nets by MEMBERSHIP** — a maximum-weight (greedy) bipartite match on the
Jaccard overlap of pin-membership sets, *never* on display name. A rename with
identical connectivity is reported as a name-only change; a connectivity change
is reported separately.
* **components by UniqueID** (the stable Altium identity, when both sides carry
it) → then a ``(value, footprint, pin-count)`` *signature* → then refdes. The
resulting designator-rename map is applied to net membership before the Jaccard
pass, so a part renamed ``R7``→``R8`` does not desync every net it touches.
When the two schematics share no UniqueIDs (the usual *cross-revision* case) the
report is flagged ``low_confidence`` with an explanatory note — a signature/
refdes/membership match is a heuristic, not ground truth.
``run(a, b) -> DiffReport`` is pure and deterministic.
"""
from __future__ import annotations
from dataclasses import dataclass, field
from ..model import SCHEMA_VERSION, Component, Net, PinRef, Schematic
from ..report import Finding, Severity
# A matched net pair below this Jaccard overlap is treated as "no match" (the two
# nets become an add/remove pair instead). Kept deliberately low so that a net
# which merely gains or loses a pin still matches its prior self, while two
# genuinely unrelated nets that happen to brush one shared pin do not.
MIN_JACCARD = 0.34
# Net-match Jaccard below this is itself evidence of a shaky (low-confidence) diff.
_SHAKY_JACCARD = 0.5
# Component fields compared field-by-field on a matched pair.
_COMPARED_FIELDS = ("designator", "value", "footprint", "library_ref", "rotation", "mirror")
ComponentSig = tuple[str | None, str | None, int]
# --------------------------------------------------------------------------- #
# Report data model (DiffReport lives here — model.py is frozen)
# --------------------------------------------------------------------------- #
@dataclass
class ComponentChange:
"""One component across the two revisions.
``method`` is how the pair was matched (``unique_id`` / ``signature`` /
``refdes``) or ``added`` / ``removed`` when it exists on only one side.
``field_changes`` maps a field name to ``(old, new)``.
"""
designator_a: str | None
designator_b: str | None
method: str
confidence: float
field_changes: dict[str, tuple] = field(default_factory=dict)
@property
def changed(self) -> bool:
return bool(self.field_changes)
def export(self) -> dict:
return {
"designator_a": self.designator_a,
"designator_b": self.designator_b,
"method": self.method,
"confidence": round(self.confidence, 4),
"field_changes": {k: list(v) for k, v in self.field_changes.items()},
}
@dataclass
class NetChange:
"""One net across the two revisions, matched by pin membership (not name)."""
name_a: str | None
name_b: str | None
stable_id_a: str | None
stable_id_b: str | None
method: str # "membership" | "added" | "removed"
jaccard: float
added_members: list[PinRef] = field(default_factory=list)
removed_members: list[PinRef] = field(default_factory=list)
name_changed: bool = False
membership_changed: bool = False
confidence: float = 1.0
def export(self) -> dict:
return {
"name_a": self.name_a,
"name_b": self.name_b,
"stable_id_a": self.stable_id_a,
"stable_id_b": self.stable_id_b,
"method": self.method,
"jaccard": round(self.jaccard, 4),
# "REF.PIN" strings — the ONE member encoding shared with
# `net`/`nets` (agents keep a single parser across the family)
"added_members": [f"{d}.{p}" for d, p in self.added_members],
"removed_members": [f"{d}.{p}" for d, p in self.removed_members],
"name_changed": self.name_changed,
"membership_changed": self.membership_changed,
"confidence": round(self.confidence, 4),
}
@dataclass
class DiffReport:
"""Result of ``run(a, b)``."""
component_changes: list[ComponentChange]
net_changes: list[NetChange]
low_confidence: bool = False
notes: list[str] = field(default_factory=list)
rename_map: dict[str, str] = field(default_factory=dict)
# -- component views ---------------------------------------------------- #
@property
def added_components(self) -> list[ComponentChange]:
return [c for c in self.component_changes if c.method == "added"]
@property
def removed_components(self) -> list[ComponentChange]:
return [c for c in self.component_changes if c.method == "removed"]
@property
def matched_components(self) -> list[ComponentChange]:
return [c for c in self.component_changes if c.method not in ("added", "removed")]
@property
def changed_components(self) -> list[ComponentChange]:
return [c for c in self.matched_components if c.changed]
# -- net views ---------------------------------------------------------- #
@property
def added_nets(self) -> list[NetChange]:
return [n for n in self.net_changes if n.method == "added"]
@property
def removed_nets(self) -> list[NetChange]:
return [n for n in self.net_changes if n.method == "removed"]
@property
def matched_nets(self) -> list[NetChange]:
return [n for n in self.net_changes if n.method == "membership"]
@property
def renamed_nets(self) -> list[NetChange]:
"""Matched nets whose display name changed but membership did NOT."""
return [n for n in self.matched_nets if n.name_changed and not n.membership_changed]
@property
def member_changed_nets(self) -> list[NetChange]:
"""Matched nets whose pin membership changed (name may or may not differ)."""
return [n for n in self.matched_nets if n.membership_changed]
def summary(self) -> dict:
return {
"components": {
"added": len(self.added_components),
"removed": len(self.removed_components),
"changed": len(self.changed_components),
"matched": len(self.matched_components),
},
"nets": {
"added": len(self.added_nets),
"removed": len(self.removed_nets),
"renamed": len(self.renamed_nets),
"membership_changed": len(self.member_changed_nets),
"matched": len(self.matched_nets),
},
"low_confidence": self.low_confidence,
}
def export(self) -> dict:
return {
"schema_version": SCHEMA_VERSION,
"summary": self.summary(),
"low_confidence": self.low_confidence,
"notes": list(self.notes),
"rename_map": dict(self.rename_map),
"component_changes": [c.export() for c in self.component_changes],
"net_changes": [n.export() for n in self.net_changes],
}
def findings(self) -> list[Finding]:
"""Render the diff as report ``Finding`` objects (for the CLI ``diff``)."""
out: list[Finding] = []
if self.low_confidence:
note = self.notes[0] if self.notes else "cross-revision heuristic match"
out.append(
Finding(
"DIFF_LOW_CONFIDENCE",
Severity.NOTE,
f"low-confidence diff: {note}",
)
)
for c in self.removed_components:
out.append(
Finding("DIFF_COMPONENT_REMOVED", Severity.WARNING,
f"component removed: {c.designator_a}", [c.designator_a])
)
for c in self.added_components:
out.append(
Finding("DIFF_COMPONENT_ADDED", Severity.WARNING,
f"component added: {c.designator_b}", [c.designator_b])
)
for c in self.changed_components:
bits = ", ".join(f"{k}: {old!r}->{new!r}" for k, (old, new) in sorted(c.field_changes.items()))
ref = c.designator_b or c.designator_a
out.append(
Finding("DIFF_COMPONENT_CHANGED", Severity.WARNING,
f"component {ref} changed ({c.method}): {bits}", [ref])
)
for n in self.removed_nets:
out.append(
Finding("DIFF_NET_REMOVED", Severity.WARNING,
f"net removed: {_net_label(n.name_a, n.stable_id_a)}")
)
for n in self.added_nets:
out.append(
Finding("DIFF_NET_ADDED", Severity.WARNING,
f"net added: {_net_label(n.name_b, n.stable_id_b)}")
)
for n in self.member_changed_nets:
adds = ", ".join(f"{d}.{p}" for d, p in n.added_members)
rems = ", ".join(f"{d}.{p}" for d, p in n.removed_members)
detail = []
if adds:
detail.append(f"+[{adds}]")
if rems:
detail.append(f"-[{rems}]")
label = _net_label(n.name_b or n.name_a, n.stable_id_b)
out.append(
Finding("DIFF_NET_MEMBERSHIP", Severity.WARNING,
f"net {label} membership changed: {' '.join(detail)}")
)
for n in self.renamed_nets:
out.append(
Finding("DIFF_NET_RENAMED", Severity.NOTE,
f"net renamed (same membership): {n.name_a!r} -> {n.name_b!r}")
)
return out
def _net_label(name: str | None, stable_id: str | None) -> str:
if name:
return name
return f"<unnamed {stable_id}>" if stable_id else "<unnamed>"
# --------------------------------------------------------------------------- #
# Component matching
# --------------------------------------------------------------------------- #
def _signature(c: Component) -> ComponentSig:
return (c.value, c.footprint, len(c.pins))
def _sig_is_distinct(c: Component) -> bool:
"""A signature is matchable only if it carries a distinguishing attribute.
Pin-count alone is far too weak to assert identity: two unrelated parts that
both have no value and no footprint (e.g. ``(None, None, 2)``) would otherwise
be force-matched, silently hiding real add/remove pairs and — worse — remapping
net membership so disjoint nets appear identical. Require value OR footprint.
"""
return bool(c.value) or bool(c.footprint)
def _field_changes(a: Component, b: Component) -> dict[str, tuple]:
changes: dict[str, tuple] = {}
for f in _COMPARED_FIELDS:
av, bv = getattr(a, f), getattr(b, f)
if av != bv:
changes[f] = (av, bv)
if len(a.pins) != len(b.pins):
changes["pin_count"] = (len(a.pins), len(b.pins))
return changes
def _match_components(
a_comps: list[Component], b_comps: list[Component]
) -> tuple[list[tuple[Component, Component, str, float]], list[Component], list[Component], int]:
"""Greedy 3-pass match. Returns (pairs, removed_only_a, added_only_b, uid_count)."""
pool_a = list(a_comps)
pool_b = list(b_comps)
pairs: list[tuple[Component, Component, str, float]] = []
uid_count = 0
# Pass 1: UniqueID (exact, non-empty, unambiguous on each side).
b_by_uid: dict[str, list[Component]] = {}
for c in pool_b:
if c.unique_id:
b_by_uid.setdefault(c.unique_id, []).append(c)
matched_b: set[int] = set()
rest_a: list[Component] = []
for ca in pool_a:
cand = b_by_uid.get(ca.unique_id or "")
chosen = None
if cand:
# prefer an as-yet-unused candidate (defensive against dup uids)
for cb in cand:
if id(cb) not in matched_b:
chosen = cb
break
if chosen is not None:
matched_b.add(id(chosen))
pairs.append((ca, chosen, "unique_id", 1.0))
uid_count += 1
else:
rest_a.append(ca)
pool_a = rest_a
pool_b = [c for c in pool_b if id(c) not in matched_b]
# Pass 2: (value, footprint, pin-count) signature; refdes used as tie-breaker.
b_by_sig: dict[ComponentSig, list[Component]] = {}
for c in pool_b:
if _sig_is_distinct(c):
b_by_sig.setdefault(_signature(c), []).append(c)
rest_a = []
used_b: set[int] = set()
for ca in pool_a:
if not _sig_is_distinct(ca):
rest_a.append(ca)
continue
bucket = [c for c in b_by_sig.get(_signature(ca), []) if id(c) not in used_b]
if not bucket:
rest_a.append(ca)
continue
same_ref = [c for c in bucket if c.designator == ca.designator]
chosen = same_ref[0] if same_ref else bucket[0]
used_b.add(id(chosen))
conf = 0.9 if chosen.designator == ca.designator else 0.75
pairs.append((ca, chosen, "signature", conf))
pool_a = rest_a
pool_b = [c for c in pool_b if id(c) not in used_b]
# Pass 3: refdes (signature differed, e.g. value/footprint edit).
b_by_ref: dict[str, list[Component]] = {}
for c in pool_b:
b_by_ref.setdefault(c.designator, []).append(c)
rest_a = []
used_b = set()
for ca in pool_a:
bucket = [c for c in b_by_ref.get(ca.designator, []) if id(c) not in used_b]
if not bucket:
rest_a.append(ca)
continue
chosen = bucket[0]
used_b.add(id(chosen))
pairs.append((ca, chosen, "refdes", 0.6))
pool_a = rest_a
pool_b = [c for c in pool_b if id(c) not in used_b]
return pairs, pool_a, pool_b, uid_count
# --------------------------------------------------------------------------- #
# Net matching (Jaccard bipartite, on remapped membership)
# --------------------------------------------------------------------------- #
def _translate_members(members: list[PinRef], rename: dict[str, str]) -> frozenset[PinRef]:
return frozenset((rename.get(d, d), p) for d, p in members)
def _names_differ(name_a: str | None, name_b: str | None, net_a: Net, net_b: Net) -> bool:
if name_a == name_b:
return False
# A name that survives only as an alias on the other side is not a "rename".
if name_a and name_a in (net_b.aliases or []):
return False
if name_b and name_b in (net_a.aliases or []):
return False
return True
def _match_nets(
a_nets: list[Net], b_nets: list[Net], rename: dict[str, str]
) -> list[NetChange]:
a_sets = [_translate_members(n.members, rename) for n in a_nets]
b_sets = [frozenset(n.members) for n in b_nets]
candidates: list[tuple[float, int, int]] = []
for i, asn in enumerate(a_sets):
if not asn:
continue
for j, bsn in enumerate(b_sets):
if not bsn:
continue
inter = asn & bsn
if not inter:
continue
jac = len(inter) / len(asn | bsn)
if jac >= MIN_JACCARD:
candidates.append((jac, i, j))
# Greedy maximum-weight bipartite match (deterministic tie-break by index).
candidates.sort(key=lambda t: (-t[0], t[1], t[2]))
used_a: set[int] = set()
used_b: set[int] = set()
matched: list[tuple[int, int, float]] = []
for jac, i, j in candidates:
if i in used_a or j in used_b:
continue
used_a.add(i)
used_b.add(j)
matched.append((i, j, jac))
changes: list[NetChange] = []
for i, j, jac in matched:
na, nb = a_nets[i], b_nets[j]
a_set, b_set = a_sets[i], b_sets[j]
added = sorted(b_set - a_set)
removed = sorted(a_set - b_set)
name_changed = _names_differ(na.name, nb.name, na, nb)
membership_changed = jac < 1.0
changes.append(
NetChange(
name_a=na.name,
name_b=nb.name,
stable_id_a=na.stable_id,
stable_id_b=nb.stable_id,
method="membership",
jaccard=jac,
added_members=added,
removed_members=removed,
name_changed=name_changed,
membership_changed=membership_changed,
confidence=jac,
)
)
for i, na in enumerate(a_nets):
if i in used_a or not a_sets[i]:
continue
changes.append(
NetChange(na.name, None, na.stable_id, None, "removed", 0.0,
removed_members=sorted(a_sets[i]))
)
for j, nb in enumerate(b_nets):
if j in used_b or not b_sets[j]:
continue
changes.append(
NetChange(None, nb.name, None, nb.stable_id, "added", 0.0,
added_members=sorted(b_sets[j]))
)
# Stable ordering: matched first (by a-index), then removed, then added.
order = {"membership": 0, "removed": 1, "added": 2}
changes.sort(key=lambda n: (order[n.method], n.name_a or "", n.name_b or "", n.stable_id_a or "", n.stable_id_b or ""))
return changes
# --------------------------------------------------------------------------- #
# Public entry point
# --------------------------------------------------------------------------- #
def run(a: Schematic, b: Schematic) -> DiffReport:
"""Diff schematic ``a`` (old) against ``b`` (new). Deterministic, pure."""
pairs, removed_a, added_b, uid_count = _match_components(a.components, b.components)
# designator-rename map (a.designator -> b.designator) from every matched pair,
# used to translate A's net membership into B's namespace before the Jaccard pass.
rename: dict[str, str] = {}
for ca, cb, _method, _conf in pairs:
if ca.designator != cb.designator:
rename[ca.designator] = cb.designator
component_changes: list[ComponentChange] = []
for ca, cb, method, conf in pairs:
component_changes.append(
ComponentChange(ca.designator, cb.designator, method, conf, _field_changes(ca, cb))
)
for ca in removed_a:
component_changes.append(ComponentChange(ca.designator, None, "removed", 1.0))
for cb in added_b:
component_changes.append(ComponentChange(None, cb.designator, "added", 1.0))
net_changes = _match_nets(a.nets, b.nets, rename)
# Confidence: cross-revision (no shared UniqueIDs) or shaky net overlaps.
total_matched = len(pairs)
uid_ratio = (uid_count / total_matched) if total_matched else 1.0
shaky_net = any(
n.method == "membership" and n.jaccard < _SHAKY_JACCARD for n in net_changes
)
notes: list[str] = []
low_confidence = False
if total_matched and uid_ratio < 0.5:
low_confidence = True
if uid_count == 0:
notes.append(
"no shared UniqueIDs between revisions; components matched by "
"signature/refdes (heuristic, not authoritative)"
)
else:
notes.append(
f"only {uid_count}/{total_matched} components matched by UniqueID; "
"the rest by signature/refdes heuristic"
)
if shaky_net:
low_confidence = True
notes.append("some nets matched on weak membership overlap (Jaccard < 0.5)")
# Lower per-net confidence when the whole diff is cross-revision heuristic.
if low_confidence:
for n in net_changes:
if n.method == "membership":
n.confidence = min(n.confidence, 0.6)
return DiffReport(
component_changes=component_changes,
net_changes=net_changes,
low_confidence=low_confidence,
notes=notes,
rename_map=rename,
)