Resolve wasm traps to unit source

scripts/test_unit_export_surface.sh

@@ -50,7 +50,7 @@ fi
 
 entry_wasm="$artifact_dir/entry.uce.wasm"
 named_wasm="$artifact_dir/named.uce.wasm"
-python3 - "$entry_wasm" "$named_wasm" <<'PY'
+python3 - "$entry_wasm" "$named_wasm" "$absolute_source_dir" <<'PY'
 import sys
 from pathlib import Path
 
@@ -60,9 +60,10 @@ cases = [
     (Path(sys.argv[1]), {"__wasm_call_ctors", "__uce_set_current_request", "__uce_cli", "visibility_shared"}, b"uce-private-unused-marker-8f61d2"),
     (Path(sys.argv[2]), {"__wasm_call_ctors", "__uce_set_current_request", "__uce_component_NAMED", "named_shared"}, b"uce-named-unused-marker-4ae973"),
 ]
+source_dir = Path(sys.argv[3])
 for path, allowed, unused_marker in cases:
     data = path.read_bytes()
-    _, imports, exports = collect(path)
+    customs, imports, exports = collect(path)
     names = {name for name, _ in exports}
     unexpected = names - allowed
     missing = allowed - names
@@ -74,6 +75,18 @@ for path, allowed, unused_marker in cases:
         raise SystemExit(f"{path}: retained {len(imports)} imports (expected fewer than 40)")
     if path.stat().st_size >= 1024 * 1024:
         raise SystemExit(f"{path}: artifact is {path.stat().st_size} bytes (expected under 1 MiB)")
+    source_map = Path(str(path) + ".source-map")
+    if not source_map.is_file() or source_map.stat().st_size >= 256 * 1024:
+        raise SystemExit(f"{path}: missing or oversized source map")
+    module = customs["uce.module"][-1].decode()
+    lines = source_map.read_text().splitlines()
+    if not lines or lines[0] != f"UCE_SOURCE_MAP_V1\t{module}":
+        raise SystemExit(f"{path}: source map does not match wasm module identity")
+    expected_source = str(source_dir / path.name.removesuffix(".wasm"))
+    if not any(line.startswith("F\t") and line.endswith("\t" + expected_source) for line in lines):
+        raise SystemExit(f"{path}: source map does not identify {expected_source}")
+    if not any(line.startswith("L\t") for line in lines):
+        raise SystemExit(f"{path}: source map has no address rows")
 PY
 
 echo "unit export surface passed"