Share library/extracted for schematic and PCB review.

PCB AI skips a second PDF exam (pintable cache, pdf_path=None) and the report
gains a PCB exam section plus power-trace, thermal, via, Kelvin, and GND-stitch
checks grounded in board geometry and extracted specs.

backend/services/validation.py

@@ -288,7 +288,7 @@ async def review_ic_async(
     graph: DesignGraph,
     constraints_map: ConstraintsMap,
     ic_ref: str,
-    pdf_path: str,
+    pdf_path: str | None,
     on_progress: ProgressCallback | None = None,
     api_logger: ApiLogger | None = None,
     trace_git_commit: str = "unknown",
@@ -301,21 +301,21 @@ async def review_ic_async(
 ) -> tuple[ReviewResult, dict]:
     """Review one IC against its datasheet. Async, multi-turn.
 
-    Returns ``(ReviewResult, trace)`` — ``trace`` is a transcript dict of the
-    full agentic loop (turns, tool calls + outputs, final submission) for
-    offline inspection. Trace assembly is best-effort and never affects the
-    review result.
+    ``pdf_path`` may be ``None`` when the caller already has library
+    extraction (PCB layout-only exam) — no PDF is attached and citations
+    are not re-verified against a PDF.
     """
     comp = graph.components[ic_ref]
     mpn = comp.mpn or comp.value
 
     # Datasheet identity for the trace — hash the original PDF, not the
     # trimmed copy, so the reference is stable across trim-heuristic changes.
-    try:
-        ds_md5 = hashlib.md5(Path(pdf_path).read_bytes()).hexdigest()
-    except Exception:
-        log.exception("trace: datasheet md5 failed for %s", ic_ref)
-        ds_md5 = None
+    ds_md5 = None
+    if pdf_path:
+        try:
+            ds_md5 = hashlib.md5(Path(pdf_path).read_bytes()).hexdigest()
+        except Exception:
+            log.exception("trace: datasheet md5 failed for %s", ic_ref)
 
     # Pre-compute which designators the excerpt tool will accept for this
     # review (neighbors via signal nets only — power/GND fan-out filtered).
@@ -338,7 +338,7 @@ async def review_ic_async(
         current_ic=ic_ref,
         connected_designators=connected_designators,
         graph=graph,
-        pdf_dir=pdf_dir or Path(pdf_path).parent,
+        pdf_dir=pdf_dir or (Path(pdf_path).parent if pdf_path else Path(".")),
         storage=storage,
         cache=excerpt_cache if excerpt_cache is not None else {},
         fetch_budget=_PER_REVIEW_FETCH_BUDGET,
@@ -347,7 +347,7 @@ async def review_ic_async(
     )
 
     # Trim PDF up-front — both primary and fallback attempts share it.
-    trimmed_pdf = _select_review_pages(pdf_path)
+    trimmed_pdf = _select_review_pages(pdf_path) if pdf_path else None
     try:
         async def _run(provider, model) -> tuple[ReviewResult, dict]:
             t0 = time.monotonic()
@@ -377,15 +377,13 @@ async def review_ic_async(
                 if extra_context.strip():
                     user_text += "\n\n" + extra_context.strip()
 
+                user_blocks: list = []
+                if trimmed_pdf:
+                    user_blocks.append(PdfBlock(path=Path(trimmed_pdf), cacheable=True))
+                user_blocks.append(TextBlock(text=user_text, cacheable=True))
                 initial_msg = Message(
                     role="user",
-                    content=[
-                        PdfBlock(path=Path(trimmed_pdf), cacheable=True),
-                        TextBlock(
-                            text=user_text,
-                            cacheable=True,
-                        ),
-                    ],
+                    content=user_blocks,
                 )
                 messages: list[Message] = [initial_msg]
 
@@ -465,13 +463,14 @@ async def review_ic_async(
                                 mpn_by_designator=mpn_by_designator,
                                 connected=connected_designators,
                             )
-                            verify_finding_citations(
-                                result.findings,
-                                default_pdf=Path(pdf_path),
-                                default_mpn=mpn,
-                                pdf_dir=excerpt_state.pdf_dir,
-                                mpn_by_designator=mpn_by_designator,
-                            )
+                            if pdf_path:
+                                verify_finding_citations(
+                                    result.findings,
+                                    default_pdf=Path(pdf_path),
+                                    default_mpn=mpn,
+                                    pdf_dir=excerpt_state.pdf_dir,
+                                    mpn_by_designator=mpn_by_designator,
+                                )
                             turn_record["tool_calls"].append({
                                 "name": "submit_review",
                                 "input": tc.input,
@@ -610,7 +609,7 @@ async def review_ic_async(
 
         return await call_with_fallback("validation", _run)
     finally:
-        if trimmed_pdf != pdf_path:
+        if trimmed_pdf and pdf_path and trimmed_pdf != pdf_path:
             Path(trimmed_pdf).unlink(missing_ok=True)