diff --git a/backend/pinscopex/validation_tools.py b/backend/pinscopex/validation_tools.py
index 96c203a..c75461c 100644
--- a/backend/pinscopex/validation_tools.py
+++ b/backend/pinscopex/validation_tools.py
@@ -317,18 +317,24 @@ def _resolve_neighbor_pdf(
     Mirrors validation._find_pdf's local-then-library lookup so neighbor
     datasheets follow the same resolution rules as the IC under review.
     """
-    safe = safe_mpn(mpn)
-    local = state.pdf_dir / f"{safe}.pdf"
-    if local.is_file():
+    from backend.services.datasheet_finder import find_local_pdf
+
+    local = find_local_pdf(state.pdf_dir, mpn)
+    if local is not None and local.is_file():
+        wanted = state.pdf_dir / f"{safe_mpn(mpn)}.pdf"
+        if local.resolve() != wanted.resolve() and not wanted.is_file():
+            wanted.write_bytes(local.read_bytes())
+            return wanted
         return local
     if state.storage is not None:
         try:
             from backend.services import projects as proj_svc
             lib_key = proj_svc.library_has_datasheet(state.storage, mpn)
             if lib_key:
-                state.storage.download_to_local(lib_key, local)
-                if local.is_file():
-                    return local
+                wanted = state.pdf_dir / f"{safe_mpn(mpn)}.pdf"
+                state.storage.download_to_local(lib_key, wanted)
+                if wanted.is_file():
+                    return wanted
         except Exception:
             log.exception("excerpt: library lookup failed for %s", mpn)
     return None
diff --git a/backend/services/datasheet_finder.py b/backend/services/datasheet_finder.py
index 61a22fa..b8d3383 100644
--- a/backend/services/datasheet_finder.py
+++ b/backend/services/datasheet_finder.py
@@ -19,6 +19,7 @@ from __future__ import annotations
 import logging
 import re
 from dataclasses import dataclass
+from pathlib import Path
 
 import httpx
 
@@ -138,6 +139,34 @@ def mpn_catalog_match(query: str, candidate: str) -> bool:
     return c.startswith(q) and len(c) > len(q)
 
 
+def find_local_pdf(pdf_dir: Path, mpn: str) -> Path | None:
+    """Find a datasheet PDF whose filename is this MPN or a catalog alias.
+
+    ``ESP32-S31-WROOM-3`` matches ``ESP32-S31-WROOM-3-N16R16V.pdf`` and the
+    reverse — packing / flash-size suffixes, not sibling dies (CH340 vs CH340E).
+    """
+    from backend.pinscopex.utils import safe_mpn
+
+    if not mpn or not pdf_dir.is_dir():
+        return None
+    for name in mpn_query_variants(mpn) or [mpn]:
+        hit = pdf_dir / f"{safe_mpn(name)}.pdf"
+        if hit.is_file():
+            return hit
+    want = _alnum(mpn)
+    if len(want) < _MIN_FAMILY_LEN:
+        return None
+    family_hit: Path | None = None
+    for hit in pdf_dir.glob("*.pdf"):
+        stem = hit.stem
+        if mpn_matches(mpn, stem) or mpn_catalog_match(mpn, stem) or mpn_catalog_match(stem, mpn):
+            got = _alnum(stem)
+            if got == want or mpn_matches(mpn, stem):
+                return hit
+            family_hit = family_hit or hit
+    return family_hit
+
+
 def _pick_lcsc_product(mpn: str, products: list[dict]) -> dict | None:
     exact: dict | None = None
     loose: dict | None = None
diff --git a/backend/services/passive_from_mpn.py b/backend/services/passive_from_mpn.py
new file mode 100644
index 0000000..5300fab
--- /dev/null
+++ b/backend/services/passive_from_mpn.py
@@ -0,0 +1,139 @@
+"""Decode common chip R/C MPNs into typed specs without an LLM.
+
+Only encodings that carry package + value (and voltage for capacitors when
+the manufacturer puts it in the code) are accepted. Incomplete BOM-value
+guesses stay out of the shared library.
+"""
+
+from __future__ import annotations
+
+import re
+
+from backend.pinscopex.models import ComponentModel, SimpleComponentSpecs
+from backend.pinscopex.resolve_passives import simple_to_typed_passive_specs
+from backend.services.passive_from_distributor import _spice
+
+_SIZE = r"(?:0201|0402|0603|0805|1206|1210|1812|2010|2512)"
+_DIEL = r"(?:C0G|NP0|CG|X8R|X7R|X7S|X6S|X5R|Y5V)"
+_TOL = {
+    "B": "±0.1%",
+    "C": "±0.25%",
+    "D": "±0.5%",
+    "F": "±1%",
+    "G": "±2%",
+    "J": "±5%",
+    "K": "±10%",
+    "M": "±20%",
+}
+_AVX_V = {
+    "4": "4V",
+    "6": "6.3V",
+    "Z": "10V",
+    "Y": "16V",
+    "3": "25V",
+    "5": "50V",
+    "1": "100V",
+    "2": "200V",
+    "7": "500V",
+}
+_AVX_DIEL = {"A": "C0G", "C": "X7R", "D": "X5R", "Z": "Y5V"}
+_DIEL_NORM = {"CG": "C0G", "NP0": "C0G"}
+
+_WALSIN_CAP = re.compile(
+    rf"^({_SIZE})({_DIEL})(\d{{3}})([{''.join(_TOL)}])(\d{{3}}|[0-9]R[0-9])",
+    re.IGNORECASE,
+)
+_AVX_CAP = re.compile(
+    rf"^({_SIZE})([46ZY35127])([{''.join(_AVX_DIEL)}])(\d{{3}})([{''.join(_TOL)}])",
+    re.IGNORECASE,
+)
+_CHIP_R = re.compile(
+    rf"^(?:FRC)?({_SIZE})(?:W\d)?([{''.join('FJKG')}])(\d{{4}})",
+    re.IGNORECASE,
+)
+
+
+def _eia3_pf(digits: str) -> float:
+    return float(int(digits[:2]) * (10 ** int(digits[2])))
+
+
+def _eia3_volts(code: str) -> str | None:
+    code = code.upper()
+    if "R" in code:
+        try:
+            return f"{float(code.replace('R', '.')):g}V"
+        except ValueError:
+            return None
+    if len(code) != 3 or not code.isdigit():
+        return None
+    volts = int(code[:2]) * (10 ** int(code[2]))
+    return f"{volts}V"
+
+
+def _eia4_ohm(digits: str) -> float:
+    return float(int(digits[:3]) * (10 ** int(digits[3])))
+
+
+def _model(mpn: str, subtype: str, values: dict[str, str]) -> ComponentModel | None:
+    specs = SimpleComponentSpecs(
+        specs_type="passive",
+        component_subtype=subtype,
+        values=values,
+    )
+    try:
+        typed = simple_to_typed_passive_specs(specs)
+    except (ValueError, TypeError):
+        return None
+    return ComponentModel(mpn=mpn, specs=typed)
+
+
+def specs_from_mpn(mpn: str) -> ComponentModel | None:
+    """Return a ComponentModel when the MPN itself encodes enough specs."""
+    raw = (mpn or "").strip()
+    if not raw:
+        return None
+
+    m = _WALSIN_CAP.match(raw)
+    if m:
+        size, diel, cap, tol, volt = m.groups()
+        pf = _eia3_pf(cap)
+        values = {
+            "value_farads": _spice(str(pf), "p", "F") if pf else None,
+            "package": size.upper(),
+            "dielectric": _DIEL_NORM.get(diel.upper(), diel.upper()),
+            "tolerance": _TOL[tol.upper()],
+        }
+        rated = _eia3_volts(volt)
+        if rated:
+            values["voltage_rating_v"] = rated
+        values["value_formatted"] = values["value_farads"]
+        if values["value_farads"]:
+            return _model(raw, "passive.capacitor.ceramic", values)
+
+    m = _AVX_CAP.match(raw)
+    if m:
+        size, vcode, diel, cap, tol = m.groups()
+        pf = _eia3_pf(cap)
+        values = {
+            "value_farads": _spice(str(pf), "p", "F"),
+            "value_formatted": _spice(str(pf), "p", "F"),
+            "package": size.upper(),
+            "dielectric": _AVX_DIEL[diel.upper()],
+            "tolerance": _TOL[tol.upper()],
+            "voltage_rating_v": _AVX_V[vcode.upper()],
+        }
+        return _model(raw, "passive.capacitor.ceramic", values)
+
+    m = _CHIP_R.match(raw)
+    if m:
+        size, tol, code = m.groups()
+        ohms = _eia4_ohm(code)
+        values = {
+            "value_ohms": _spice(str(ohms), None, "ohm"),
+            "value_formatted": _spice(str(ohms), None, "ohm"),
+            "package": size.upper(),
+            "tolerance": _TOL[tol.upper()],
+        }
+        return _model(raw, "passive.resistor.thick_film", values)
+
+    return None
diff --git a/backend/services/pipeline.py b/backend/services/pipeline.py
index f3ab1c3..9b655fa 100644
--- a/backend/services/pipeline.py
+++ b/backend/services/pipeline.py
@@ -681,15 +681,16 @@ async def _ensure_local_datasheet(
     """
     if pdf_path.is_file():
         return True
-    from backend.services.datasheet_finder import find_datasheet, mpn_query_variants
+    from backend.services.datasheet_finder import find_datasheet, find_local_pdf, mpn_query_variants
+
+    alt = find_local_pdf(pdf_path.parent, mpn)
+    if alt is not None and alt.is_file():
+        if alt.resolve() != pdf_path.resolve():
+            pdf_path.parent.mkdir(parents=True, exist_ok=True)
+            pdf_path.write_bytes(alt.read_bytes())
+        return True
 
     for name in mpn_query_variants(mpn) or [mpn]:
-        alt = pdf_path.parent / f"{safe_mpn(name)}.pdf"
-        if alt.is_file():
-            if alt.resolve() != pdf_path.resolve():
-                pdf_path.parent.mkdir(parents=True, exist_ok=True)
-                pdf_path.write_bytes(alt.read_bytes())
-            return True
         lib_ds_key = proj_svc.library_has_datasheet(ctx.storage, name)
         if lib_ds_key:
             ctx.storage.download_to_local(lib_ds_key, pdf_path)
@@ -1116,6 +1117,16 @@ async def _catalog_resolve_unresolved_passives(
                     except Exception as e:
                         first_error = str(e)
 
+                if model is None:
+                    from backend.services.passive_from_mpn import specs_from_mpn
+                    model = specs_from_mpn(mpn)
+                    if model is not None:
+                        resolved_via = "mpn"
+                        broker.publish(ctx.project_id, "step_update",
+                                       {"stage": "passive_extraction",
+                                        "substep": mpn, "status": "running",
+                                        "detail": "decoded from MPN"})
+
                 if model is None:
                     bom_value = ctx.passive_values.get(mpn, "").strip()
                     refs = ctx.passive_mpns.get(mpn, [])
@@ -1152,7 +1163,7 @@ async def _catalog_resolve_unresolved_passives(
                 model_path.write_text(model.model_dump_json(indent=2) + "\n")
                 model_key = f"{ctx.ws.prefix}/models/{safe}.json"
                 ctx.storage.upload_from_local(model_path, model_key)
-                if resolved_via in ("digikey", "lcsc"):
+                if resolved_via in ("digikey", "lcsc", "mpn"):
                     proj_svc.save_to_library(
                         ctx.storage, model_key, "passives", f"{safe}.json",
                     )
@@ -1161,6 +1172,7 @@ async def _catalog_resolve_unresolved_passives(
                 detail = {
                     "lcsc": "auto-resolved via LCSC",
                     "digikey": "auto-resolved via DigiKey",
+                    "mpn": "decoded from MPN (saved to library)",
                     "value": "resolved from BOM value (not saved to library)",
                 }.get(resolved_via, "resolved")
                 broker.publish(ctx.project_id, "step_update",
@@ -1502,14 +1514,16 @@ async def _stage_validation(ctx: PipelineContext) -> None:
 
     # Snapshot the full review queue so pause checkpoints can show what's left.
     # Mirrors the filter in validate_design_async: ICs with a PDF available.
+    from backend.services.datasheet_finder import find_local_pdf
+
     planned_refs: list[str] = []
     for ref, comp in ctx.graph.components.items():
         if comp.component_type != ComponentType.IC:
             continue
-        mpn = comp.mpn or comp.value
+        mpn = (comp.mpn or "").strip() or (comp.value or "").strip()
         if not mpn:
             continue
-        if (ds_dir / f"{safe_mpn(mpn)}.pdf").is_file():
+        if find_local_pdf(ds_dir, mpn) is not None:
             planned_refs.append(ref)
     ctx.all_review_refs = sorted(planned_refs, key=natural_sort_key)
 
diff --git a/backend/services/projects.py b/backend/services/projects.py
index d84e6a4..26f74e1 100644
--- a/backend/services/projects.py
+++ b/backend/services/projects.py
@@ -775,6 +775,31 @@ def save_to_library(
     return dst_key
 
 
+def _specs_param_count(specs: dict) -> int:
+    if not isinstance(specs, dict):
+        return 0
+    values = specs.get("values")
+    if isinstance(values, dict):
+        return sum(1 for v in values.values() if v not in (None, "", []))
+    skip = {"specs_type", "component_subtype"}
+    return sum(
+        1 for k, v in specs.items()
+        if k not in skip and v not in (None, "", [])
+    )
+
+
+def _catalog_model_row(data: dict, key: str, *, row_type: str) -> dict:
+    mpn = data.get("mpn", "") or key.rsplit("/", 1)[-1].replace(".json", "")
+    specs = data.get("specs", {}) or {}
+    return {
+        "mpn": mpn,
+        "type": row_type,
+        "specs_type": specs.get("specs_type", ""),
+        "subtype": specs.get("component_subtype", ""),
+        "param_count": _specs_param_count(specs),
+    }
+
+
 def list_library_catalog(storage: StorageBackend) -> dict:
     """List ICs, passive patterns, discrete specs, and datasheet refs.
 
@@ -826,26 +851,24 @@ def list_library_catalog(storage: StorageBackend) -> dict:
             continue
 
     simple_models: list[dict] = []
+    passive_parts: list[dict] = []
     seen_model_mpns: set[str] = set()
-    for prefix in ("library/models/", "library/passives/"):
+    for prefix, row_type, dest in (
+        ("library/passives/", "passive_part", passive_parts),
+        ("library/models/", "simple", simple_models),
+    ):
         for key in storage.list_prefix(prefix):
             if not key.endswith(".json"):
                 continue
             try:
                 data = storage.read_json(key)
-                mpn = data.get("mpn", "") or key.rsplit("/", 1)[-1].replace(".json", "")
+                row = _catalog_model_row(data, key, row_type=row_type)
+                mpn = row["mpn"]
                 if mpn in seen_model_mpns:
                     continue
                 seen_model_mpns.add(mpn)
-                specs = data.get("specs", {}) or {}
-                simple_models.append({
-                    "mpn": mpn,
-                    "type": "simple",
-                    "specs_type": specs.get("specs_type", ""),
-                    "subtype": specs.get("component_subtype", ""),
-                    "param_count": len(specs.get("values", {}) or {}),
-                    "has_datasheet": bool(resolve_datasheet(storage, mpn)),
-                })
+                row["has_datasheet"] = bool(resolve_datasheet(storage, mpn))
+                dest.append(row)
             except Exception:
                 continue
 
@@ -871,11 +894,13 @@ def list_library_catalog(storage: StorageBackend) -> dict:
 
     ics.sort(key=lambda r: r["mpn"].lower())
     passives.sort(key=lambda r: r["mpn"].lower())
+    passive_parts.sort(key=lambda r: r["mpn"].lower())
     simple_models.sort(key=lambda r: r["mpn"].lower())
     datasheets.sort(key=lambda r: r["mpn"].lower())
     return {
         "ics": ics,
         "passives": passives,
+        "passive_parts": passive_parts,
         "simple": simple_models,
         "datasheets": datasheets,
     }
diff --git a/backend/services/validation.py b/backend/services/validation.py
index 36ffb7d..1ac0850 100644
--- a/backend/services/validation.py
+++ b/backend/services/validation.py
@@ -571,27 +571,29 @@ def _find_pdf(
     """Find the datasheet PDF for an MPN.  Checks local dir first,
     then tries to download from the library.
     """
-    from backend.services.datasheet_finder import mpn_query_variants
+    from backend.services.datasheet_finder import find_local_pdf
     from backend.pinscopex.utils import safe_mpn as _safe
 
-    names = mpn_query_variants(mpn) or [mpn]
-    for name in names:
-        local = pdf_dir / f"{_safe(name)}.pdf"
-        if local.is_file():
-            wanted = pdf_dir / f"{_safe(mpn)}.pdf"
-            if local != wanted and not wanted.is_file():
-                wanted.write_bytes(local.read_bytes())
-                return wanted
-            return local
+    mpn = (mpn or "").strip()
+    if not mpn:
+        return None
+
+    local = find_local_pdf(pdf_dir, mpn)
+    if local is not None and local.is_file():
+        wanted = pdf_dir / f"{_safe(mpn)}.pdf"
+        if local.resolve() != wanted.resolve() and not wanted.is_file():
+            wanted.write_bytes(local.read_bytes())
+            return wanted
+        return local
 
     if storage:
         from backend.services import projects as proj_svc
         lib_key = proj_svc.library_has_datasheet(storage, mpn)
         if lib_key:
-            local = pdf_dir / f"{_safe(mpn)}.pdf"
-            storage.download_to_local(lib_key, local)
-            if local.is_file():
-                return local
+            wanted = pdf_dir / f"{_safe(mpn)}.pdf"
+            storage.download_to_local(lib_key, wanted)
+            if wanted.is_file():
+                return wanted
 
     return None
 
@@ -665,7 +667,12 @@ async def validate_design_async(
     for ref, comp in sorted(graph.components.items()):
         if comp.component_type != ComponentType.IC:
             continue
-        mpn = comp.mpn or comp.value
+        mpn = (comp.mpn or "").strip() or (comp.value or "").strip()
+        if not mpn:
+            not_reviewed.append({"designator": ref, "reason": "no MPN in BOM"})
+            if on_progress:
+                await on_progress(ref, 0, "skipped", "no MPN in BOM")
+            continue
         pdf = _find_pdf(mpn, pdf_dir_path, storage=storage)
         if pdf:
             ic_tasks.append((ref, str(pdf)))
diff --git a/frontend/src/app/(app)/admin/page.tsx b/frontend/src/app/(app)/admin/page.tsx
index 2cf5a6f..53a4b22 100644
--- a/frontend/src/app/(app)/admin/page.tsx
+++ b/frontend/src/app/(app)/admin/page.tsx
@@ -632,7 +632,11 @@ function ComponentsPanel() {
         if (!prev) return prev;
         if (type === "ic") return { ...prev, ics: prev.ics.filter((c) => c.mpn !== name) };
         if (type === "passive") return { ...prev, passives: prev.passives.filter((c) => c.mpn !== name) };
-        return { ...prev, simple: prev.simple.filter((c) => c.mpn !== name) };
+        return {
+          ...prev,
+          simple: prev.simple.filter((c) => c.mpn !== name),
+          passive_parts: (prev.passive_parts ?? []).filter((c) => c.mpn !== name),
+        };
       });
       reload();
     } catch (e) {
@@ -678,6 +682,12 @@ function ComponentsPanel() {
       c.subtype.toLowerCase().includes(lf) ||
       c.description.toLowerCase().includes(lf),
   );
+  const filteredPassiveParts = (data.passive_parts ?? []).filter(
+    (c) =>
+      c.mpn.toLowerCase().includes(lf) ||
+      c.subtype.toLowerCase().includes(lf) ||
+      c.specs_type.toLowerCase().includes(lf),
+  );
   const filteredSimple = (data.simple ?? []).filter(
     (c) =>
       c.mpn.toLowerCase().includes(lf) ||
@@ -699,6 +709,13 @@ function ComponentsPanel() {
           <span className="font-medium">{data.passives.length}</span>
           <span className="text-muted-foreground">Passive Patterns</span>
         </div>
+        {(data.passive_parts?.length ?? 0) > 0 && (
+          <div className="flex items-center gap-1.5 text-sm">
+            <Zap className="h-4 w-4 text-amber-600 dark:text-amber-400" />
+            <span className="font-medium">{data.passive_parts.length}</span>
+            <span className="text-muted-foreground">Passive MPNs</span>
+          </div>
+        )}
         {(data.simple?.length ?? 0) > 0 && (
           <div className="flex items-center gap-1.5 text-sm">
             <Zap className="h-4 w-4 text-emerald-600 dark:text-emerald-400" />
@@ -827,6 +844,57 @@ function ComponentsPanel() {
         </div>
       )}
 
+      {/* Per-MPN passive specs */}
+      {filteredPassiveParts.length > 0 && (
+        <div>
+          <h2 className="text-sm font-medium mb-2">Passive MPNs</h2>
+          <div className="rounded-lg border border-border overflow-x-auto">
+            <table className="w-full text-sm">
+              <thead>
+                <tr className="bg-muted/50 text-muted-foreground">
+                  <th className="text-left px-3 py-2 font-medium">MPN</th>
+                  <th className="text-left px-3 py-2 font-medium">Type</th>
+                  <th className="text-left px-3 py-2 font-medium">Subtype</th>
+                  <th className="text-center px-3 py-2 font-medium">Params</th>
+                  <th className="w-10 px-3 py-2" />
+                </tr>
+              </thead>
+              <tbody className="divide-y divide-border">
+                {filteredPassiveParts.map((s) => (
+                  <tr key={s.mpn} className="hover:bg-muted/30 cursor-pointer" onClick={() => handleRowClick("simple", s.mpn)}>
+                    <td className="px-3 py-2 font-mono text-xs">{s.mpn}</td>
+                    <td className="px-3 py-2">
+                      <Badge variant="secondary">{s.specs_type || "passive"}</Badge>
+                    </td>
+                    <td className="px-3 py-2">
+                      {s.subtype ? (
+                        <Badge variant="outline">{s.subtype}</Badge>
+                      ) : (
+                        <span className="text-muted-foreground">-</span>
+                      )}
+                    </td>
+                    <td className="px-3 py-2 text-center font-mono">{s.param_count}</td>
+                    <td className="px-3 py-2 text-center">
+                      <button
+                        onClick={(e) => { e.stopPropagation(); handleDelete("simple", s.mpn); }}
+                        disabled={deleting === s.mpn}
+                        className="text-muted-foreground hover:text-destructive transition-colors disabled:opacity-50"
+                      >
+                        {deleting === s.mpn ? (
+                          <Loader2 className="h-3.5 w-3.5 animate-spin" />
+                        ) : (
+                          <Trash2 className="h-3.5 w-3.5" />
+                        )}
+                      </button>
+                    </td>
+                  </tr>
+                ))}
+              </tbody>
+            </table>
+          </div>
+        </div>
+      )}
+
       {/* Simple component specs table */}
       {filteredSimple.length > 0 && (
         <div>
@@ -878,7 +946,7 @@ function ComponentsPanel() {
         </div>
       )}
 
-      {filteredICs.length === 0 && filteredPassives.length === 0 && filteredSimple.length === 0 && (
+      {filteredICs.length === 0 && filteredPassives.length === 0 && filteredPassiveParts.length === 0 && filteredSimple.length === 0 && (
         <div className="flex flex-col items-center justify-center py-12 text-muted-foreground">
           <Package className="h-8 w-8 mb-2" />
           <p className="text-sm">
diff --git a/frontend/src/app/(app)/library/page.tsx b/frontend/src/app/(app)/library/page.tsx
index 1f2636d..68abcaa 100644
--- a/frontend/src/app/(app)/library/page.tsx
+++ b/frontend/src/app/(app)/library/page.tsx
@@ -55,6 +55,17 @@ export default function LibraryPage() {
       ),
     [data, lf],
   );
+  const passiveParts = useMemo(
+    () =>
+      (data?.passive_parts ?? []).filter(
+        (c) =>
+          !lf ||
+          c.mpn.toLowerCase().includes(lf) ||
+          c.subtype.toLowerCase().includes(lf) ||
+          c.specs_type.toLowerCase().includes(lf),
+      ),
+    [data, lf],
+  );
   const simple = useMemo(
     () =>
       (data?.simple ?? []).filter(
@@ -108,6 +119,7 @@ export default function LibraryPage() {
     !data ||
     (data.ics.length === 0 &&
       data.passives.length === 0 &&
+      (data.passive_parts ?? []).length === 0 &&
       data.simple.length === 0 &&
       data.datasheets.length === 0);
 
@@ -143,8 +155,15 @@ export default function LibraryPage() {
               </span>
               <span className="flex items-center gap-1.5">
                 <Zap className="h-4 w-4 text-amber-600 dark:text-amber-400" />
+                <span className="font-medium">
+                  {(data.passive_parts ?? []).length}
+                </span>
+                <span className="text-muted-foreground">passives</span>
+              </span>
+              <span className="flex items-center gap-1.5">
+                <Zap className="h-4 w-4 text-amber-600/70 dark:text-amber-400/70" />
                 <span className="font-medium">{data.passives.length}</span>
-                <span className="text-muted-foreground">passive series</span>
+                <span className="text-muted-foreground">series</span>
               </span>
               <span className="flex items-center gap-1.5">
                 <Zap className="h-4 w-4 text-emerald-600 dark:text-emerald-400" />
@@ -169,7 +188,7 @@ export default function LibraryPage() {
             <TabsList>
               <TabsTrigger value="ics">ICs ({ics.length})</TabsTrigger>
               <TabsTrigger value="passives">
-                Passives ({passives.length})
+                Passives ({passiveParts.length + passives.length})
               </TabsTrigger>
               <TabsTrigger value="simple">
                 Discrete ({simple.length})
@@ -225,40 +244,109 @@ export default function LibraryPage() {
               )}
             </TabsContent>
 
-            <TabsContent value="passives" className="pt-4">
-              {passives.length === 0 ? (
-                <EmptyFilter label="passive series" />
+            <TabsContent value="passives" className="pt-4 space-y-6">
+              {passiveParts.length === 0 && passives.length === 0 ? (
+                <EmptyFilter label="passives" />
               ) : (
-                <div className="rounded-lg border border-border overflow-x-auto">
-                  <table className="w-full text-sm">
-                    <thead>
-                      <tr className="bg-muted/50 text-muted-foreground">
-                        <th className="text-left px-3 py-2 font-medium">Series</th>
-                        <th className="text-left px-3 py-2 font-medium">Type</th>
-                        <th className="text-left px-3 py-2 font-medium">
-                          Description
-                        </th>
-                      </tr>
-                    </thead>
-                    <tbody className="divide-y divide-border">
-                      {passives.map((p) => (
-                        <tr key={p.mpn} className="hover:bg-muted/30">
-                          <td className="px-3 py-2 font-mono text-xs">{p.mpn}</td>
-                          <td className="px-3 py-2">
-                            {p.subtype ? (
-                              <Badge variant="secondary">{p.subtype}</Badge>
-                            ) : (
-                              <span className="text-muted-foreground">—</span>
-                            )}
-                          </td>
-                          <td className="px-3 py-2 text-muted-foreground">
-                            {p.description || "—"}
-                          </td>
-                        </tr>
-                      ))}
-                    </tbody>
-                  </table>
-                </div>
+                <>
+                  {passiveParts.length > 0 && (
+                    <div className="rounded-lg border border-border overflow-x-auto">
+                      <table className="w-full text-sm">
+                        <thead>
+                          <tr className="bg-muted/50 text-muted-foreground">
+                            <th className="text-left px-3 py-2 font-medium">
+                              MPN
+                            </th>
+                            <th className="text-left px-3 py-2 font-medium">
+                              Type
+                            </th>
+                            <th className="text-center px-3 py-2 font-medium">
+                              Params
+                            </th>
+                            <th className="text-left px-3 py-2 font-medium">
+                              PDF
+                            </th>
+                          </tr>
+                        </thead>
+                        <tbody className="divide-y divide-border">
+                          {passiveParts.map((p) => (
+                            <tr key={p.mpn} className="hover:bg-muted/30">
+                              <td className="px-3 py-2 font-mono text-xs">
+                                {p.mpn}
+                              </td>
+                              <td className="px-3 py-2">
+                                <Badge variant="secondary">
+                                  {p.subtype || p.specs_type || "passive"}
+                                </Badge>
+                              </td>
+                              <td className="px-3 py-2 text-center">
+                                {p.param_count}
+                              </td>
+                              <td className="px-3 py-2">
+                                {p.has_datasheet ? (
+                                  <DatasheetLink
+                                    mpn={p.mpn}
+                                    opening={opening}
+                                    onOpen={openDatasheet}
+                                  />
+                                ) : (
+                                  <span className="text-muted-foreground">
+                                    —
+                                  </span>
+                                )}
+                              </td>
+                            </tr>
+                          ))}
+                        </tbody>
+                      </table>
+                    </div>
+                  )}
+                  {passives.length > 0 && (
+                    <div>
+                      <p className="text-xs text-muted-foreground mb-2">
+                        Series patterns — one regex covers cousin MPNs
+                      </p>
+                      <div className="rounded-lg border border-border overflow-x-auto">
+                        <table className="w-full text-sm">
+                          <thead>
+                            <tr className="bg-muted/50 text-muted-foreground">
+                              <th className="text-left px-3 py-2 font-medium">
+                                Series
+                              </th>
+                              <th className="text-left px-3 py-2 font-medium">
+                                Type
+                              </th>
+                              <th className="text-left px-3 py-2 font-medium">
+                                Description
+                              </th>
+                            </tr>
+                          </thead>
+                          <tbody className="divide-y divide-border">
+                            {passives.map((p) => (
+                              <tr key={p.mpn} className="hover:bg-muted/30">
+                                <td className="px-3 py-2 font-mono text-xs">
+                                  {p.mpn}
+                                </td>
+                                <td className="px-3 py-2">
+                                  {p.subtype ? (
+                                    <Badge variant="secondary">{p.subtype}</Badge>
+                                  ) : (
+                                    <span className="text-muted-foreground">
+                                      —
+                                    </span>
+                                  )}
+                                </td>
+                                <td className="px-3 py-2 text-muted-foreground">
+                                  {p.description || "—"}
+                                </td>
+                              </tr>
+                            ))}
+                          </tbody>
+                        </table>
+                      </div>
+                    </div>
+                  )}
+                </>
               )}
             </TabsContent>
 
diff --git a/frontend/src/lib/api.ts b/frontend/src/lib/api.ts
index 541250e..5189f4a 100644
--- a/frontend/src/lib/api.ts
+++ b/frontend/src/lib/api.ts
@@ -389,6 +389,15 @@ export interface LibraryPassive {
   regex: string;
 }
 
+export interface LibraryPassivePart {
+  mpn: string;
+  type: "passive_part";
+  specs_type: string;
+  subtype: string;
+  param_count: number;
+  has_datasheet: boolean;
+}
+
 export interface LibrarySimple {
   mpn: string;
   type: "simple";
@@ -408,6 +417,7 @@ export interface LibraryDatasheet {
 export interface LibraryCatalog {
   ics: LibraryIC[];
   passives: LibraryPassive[];
+  passive_parts?: LibraryPassivePart[];
   simple: LibrarySimple[];
   datasheets: LibraryDatasheet[];
 }
@@ -606,6 +616,7 @@ export interface AdminSimple {
 export interface AdminComponents {
   ics: AdminIC[];
   passives: AdminPassive[];
+  passive_parts?: AdminSimple[];
   simple: AdminSimple[];
 }
 
diff --git a/tests/test_library.py b/tests/test_library.py
index ee0acb0..e7a6fdd 100644
--- a/tests/test_library.py
+++ b/tests/test_library.py
@@ -78,7 +78,9 @@ def test_library_catalog_lists_ics_passives_and_pdfs(storage):
     assert cat["ics"][0]["pin_count"] == 2
     assert cat["ics"][0]["has_datasheet"] is True
     assert cat["passives"][0]["mpn"] == "Samsung CL10"
-    assert cat["simple"][0]["mpn"] == "CL10B474KA8NNNC"
+    assert cat["passive_parts"][0]["mpn"] == "CL10B474KA8NNNC"
+    assert cat["passive_parts"][0]["param_count"] >= 1
+    assert cat["simple"] == []
     assert any(d["mpn"] == "CH340E" and d["has_extraction"] for d in cat["datasheets"])
 
 
diff --git a/tests/test_passive_from_mpn.py b/tests/test_passive_from_mpn.py
new file mode 100644
index 0000000..d6b8e11
--- /dev/null
+++ b/tests/test_passive_from_mpn.py
@@ -0,0 +1,65 @@
+from pathlib import Path
+
+from backend.services.datasheet_finder import find_local_pdf
+from backend.services.passive_from_mpn import specs_from_mpn
+
+
+def test_walsin_c0g_18pf():
+    model = specs_from_mpn("0805CG180J500NT")
+    assert model is not None
+    specs = model.specs
+    assert specs.specs_type == "capacitor"
+    assert abs(specs.value_farads - 18e-12) < 1e-15
+    assert specs.package == "0805"
+    assert specs.dielectric == "C0G"
+    assert specs.tolerance == "±5%"
+    assert specs.voltage_rating_v == "50V"
+
+
+def test_avx_c0g_150pf():
+    model = specs_from_mpn("08055A151FAT2A")
+    assert model is not None
+    specs = model.specs
+    assert abs(specs.value_farads - 150e-12) < 1e-15
+    assert specs.package == "0805"
+    assert specs.dielectric == "C0G"
+    assert specs.voltage_rating_v == "50V"
+
+
+def test_chip_resistor_from_mpn():
+    model = specs_from_mpn("FRC0805F1212TS")
+    assert model is not None
+    assert abs(model.specs.value_ohms - 12100) < 0.1
+    assert model.specs.package == "0805"
+    assert model.specs.tolerance == "±1%"
+
+    model = specs_from_mpn("0805W8F2201T5E")
+    assert model is not None
+    assert abs(model.specs.value_ohms - 2200) < 0.1
+
+
+def test_skips_murata_and_bare_value():
+    assert specs_from_mpn("GRM21A5C2J200JA01") is None
+    assert specs_from_mpn("18pF") is None
+    assert specs_from_mpn("CH340E") is None
+
+
+def test_find_local_pdf_family_vs_orderable(tmp_path: Path):
+    pdf = tmp_path / "ESP32-S31-WROOM-3-N16R16V.pdf"
+    pdf.write_bytes(b"%PDF-1.4\n" + b"x" * 100)
+    hit = find_local_pdf(tmp_path, "ESP32-S31-WROOM-3")
+    assert hit is not None
+    assert hit.name == pdf.name
+
+    other = tmp_path / "only"
+    other.mkdir()
+    family = other / "ESP32-S31-WROOM-3.pdf"
+    family.write_bytes(b"%PDF-1.4\n" + b"y" * 100)
+    hit = find_local_pdf(other, "ESP32-S31-WROOM-3-N16R16V")
+    assert hit is not None
+    assert hit.name == family.name
+
+
+def test_find_local_pdf_does_not_steal_sibling_die(tmp_path: Path):
+    (tmp_path / "CH340E.pdf").write_bytes(b"%PDF-1.4\n" + b"x" * 100)
+    assert find_local_pdf(tmp_path, "CH340") is None