feat: resolve C/C++ and Rust calls across files and typed receivers

C++ calls now resolve through the include closure: header prototypes pair
with definitions in other translation units, lookup walks class (including
in-repository bases), namespace, and `using` scopes outward, and static or
anonymous-namespace definitions stay file-local. Member calls resolve only
through explicitly declared receiver types (parameters, locals, fields,
this, smart pointers, aliases); template parameters stay unknown. Calls
hidden by the most vexing parse are recovered, casts are no longer calls,
reference-returning and conversion-operator declarations are named
correctly, and benign `= {}` default-argument recoveries no longer drop
prototypes or flag files.

Rust method calls resolve through a crate-wide impl index for self, typed
parameters and lets, struct fields, Self-returning constructors, dyn
traits, and Type::/Self:: associated calls, with foreign imports and
generics never guessed. Calls inside expression macros are re-parsed.

Every unresolved call records source.unresolved-reason, weaker resolutions
record source.resolution/source.extraction, and metrics.resolution reports
per-language call-site coverage. Declarations gain facts consumed by
caller-status queries (qualified names, linkage, virtual, trait impls,
attributes, name references, parse-incomplete). C++/Rust External targets
include the reason in their identity; out-of-line C++ methods keep their
IDs.

Linear node/edge scans and per-node ancestor walks are replaced with
indexes, cutting a YAMS scan from 575 s to 23 s.

New labeled cpp_xtu and rust_methods corpora run three times in the
quality gate.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

scripts/quality-gate.sh

@@ -11,6 +11,8 @@ python3 -m unittest discover -s tests/benchmarks -p 'test_*.py'
 python3 tests/benchmarks/runner.py self-test
 python3 tests/benchmarks/runner.py run source_languages
 python3 tests/benchmarks/runner.py run rust_imports
+python3 tests/benchmarks/runner.py run cpp_xtu
+python3 tests/benchmarks/runner.py run rust_methods
 python3 tests/benchmarks/diff_runner.py self-test
 python3 tests/benchmarks/policy_runner.py self-test
 python3 tests/benchmarks/mcp_runner.py self-test

src/metrics.rs

@@ -1,8 +1,9 @@
 use crate::model::{
-    Building, Diagnostic, Edge, EdgeKind, Node, NodeKind, P4Metrics, StructuralHealth,
+    Building, Diagnostic, Edge, EdgeKind, EvidenceLane, Node, NodeKind, P4Metrics,
+    ResolutionMetrics, StructuralHealth,
 };
 use serde_json::Value;
-use std::collections::{HashMap, HashSet, VecDeque};
+use std::collections::{BTreeMap, HashMap, HashSet, VecDeque};
 
 const P4_DIAGNOSTIC_PREFIX: &str = "P4 structural observation (not verifier proof):";
 
@@ -87,6 +88,7 @@ pub fn calculate(building: &mut Building) {
     building.metrics.max_fan_in = max_fan_in;
     building.metrics.max_fan_out = max_fan_out;
     building.metrics.p4 = p4_metrics;
+    building.metrics.resolution = calculate_resolution(building);
     building.metrics.structural_health = StructuralHealth {
         score: round(score),
         experimental: true,
@@ -104,6 +106,68 @@ pub fn calculate(building: &mut Building) {
     building.diagnostics.extend(p4_diagnostics);
 }
 
+/// Counts syntactic call sites (heuristic evidence entries), not deduplicated edges.
+fn calculate_resolution(building: &Building) -> BTreeMap<String, ResolutionMetrics> {
+    let nodes: HashMap<&str, &Node> = building
+        .nodes
+        .iter()
+        .map(|node| (node.id.as_str(), node))
+        .collect();
+    let mut result: BTreeMap<String, ResolutionMetrics> = BTreeMap::new();
+    let mut called = HashSet::new();
+    for edge in building
+        .edges
+        .iter()
+        .filter(|edge| edge.kind == EdgeKind::Calls)
+    {
+        let (Some(source), Some(target)) = (
+            nodes.get(edge.source.as_str()),
+            nodes.get(edge.target.as_str()),
+        ) else {
+            continue;
+        };
+        let Some(language) = source.language.as_deref() else {
+            continue;
+        };
+        let sites = edge
+            .evidence
+            .iter()
+            .filter(|evidence| evidence.lane == EvidenceLane::Heuristic)
+            .count();
+        let metrics = result.entry(language.into()).or_default();
+        metrics.call_site_count += sites;
+        if target.kind == NodeKind::External {
+            let reason = edge
+                .attributes
+                .get("source.unresolved-reason")
+                .and_then(Value::as_str)
+                .unwrap_or("unclassified");
+            *metrics
+                .unresolved_call_sites_by_reason
+                .entry(reason.into())
+                .or_default() += sites;
+        } else {
+            metrics.resolved_call_site_count += sites;
+            called.insert(target.id.as_str());
+        }
+    }
+    for node in building
+        .nodes
+        .iter()
+        .filter(|node| node.kind == NodeKind::Function)
+    {
+        let Some(language) = node.language.as_deref() else {
+            continue;
+        };
+        let metrics = result.entry(language.into()).or_default();
+        metrics.function_count += 1;
+        if !called.contains(node.id.as_str()) {
+            metrics.functions_without_resolved_callers += 1;
+        }
+    }
+    result
+}
+
 fn calculate_p4(building: &Building) -> (P4Metrics, Vec<Diagnostic>) {
     let nodes: HashMap<&str, &Node> = building
         .nodes

src/model.rs

@@ -436,9 +436,24 @@ pub struct Metrics {
     pub max_fan_in: usize,
     pub max_fan_out: usize,
     pub p4: P4Metrics,
+    /// Per-language call-resolution coverage. Absent in models from older builds.
+    #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
+    pub resolution: BTreeMap<String, ResolutionMetrics>,
     pub structural_health: StructuralHealth,
 }
 
+/// How much of a language's call graph resolved to in-repository symbols.
+/// A symbol without resolved callers is not evidence of dead code unless the
+/// unresolved call sites that could reach it are accounted for.
+#[derive(Debug, Clone, Default, PartialEq, Eq, Serialize, Deserialize)]
+pub struct ResolutionMetrics {
+    pub call_site_count: usize,
+    pub resolved_call_site_count: usize,
+    pub unresolved_call_sites_by_reason: BTreeMap<String, usize>,
+    pub function_count: usize,
+    pub functions_without_resolved_callers: usize,
+}
+
 #[derive(Debug, Clone, Default, PartialEq, Eq, Serialize, Deserialize)]
 pub struct P4Metrics {
     pub parser_state_count: usize,

tests/benchmarks/plans/cpp_xtu.json

@@ -0,0 +1,14 @@
+{
+  "schema_version": 1,
+  "name": "cpp_xtu",
+  "corpus": "tests/fixtures/cpp_xtu/cpp",
+  "repeats": 3,
+  "direct_binary": true,
+  "measure_rss": true,
+  "expect": {
+    "min_symbols": 23,
+    "min_dependency_edges": 24,
+    "cycles": 0
+  },
+  "source_labels": "labels.json"
+}

tests/benchmarks/plans/rust_methods.json

@@ -0,0 +1,14 @@
+{
+  "schema_version": 1,
+  "name": "rust_methods",
+  "corpus": "tests/fixtures/rust_methods/rust",
+  "repeats": 3,
+  "direct_binary": true,
+  "measure_rss": true,
+  "expect": {
+    "min_symbols": 21,
+    "min_dependency_edges": 23,
+    "cycles": 0
+  },
+  "source_labels": "labels.json"
+}

tests/benchmarks/runner.py

@@ -412,7 +412,8 @@ def source_language_quality(model: dict, labels: dict) -> dict:
             if current["id"] in visited:
                 raise AssertionError("cyclic declaration ownership")
             visited.add(current["id"])
-            names.append(current["name"])
+            qualifier = current.get("attributes", {}).get("source.qualifier")
+            names.append(f"{qualifier}::{current['name']}" if qualifier else current["name"])
             current = nodes[current["parent"]]
         scope = node.get("attributes", {}).get("source.scope")
         return "::".join([node["path"], *([f"scope={scope}"] if scope else []), *reversed(names)])

tests/cpp_xtu.rs

@@ -0,0 +1,328 @@
+use brick::model::{Building, EdgeKind, Node, NodeKind};
+use brick::scan;
+use std::fs;
+
+fn scan_files(files: &[(&str, &str)]) -> Building {
+    let root = tempfile::tempdir().unwrap();
+    for (path, content) in files {
+        let file = root.path().join(path);
+        fs::create_dir_all(file.parent().unwrap()).unwrap();
+        fs::write(file, content).unwrap();
+    }
+    scan::scan(root.path()).unwrap()
+}
+
+fn function<'a>(model: &'a Building, path: &str, name: &str) -> &'a Node {
+    model
+        .nodes
+        .iter()
+        .find(|n| n.kind == NodeKind::Function && n.path.as_deref() == Some(path) && n.name == name)
+        .unwrap_or_else(|| panic!("missing {path}::{name}"))
+}
+
+/// (target node, unresolved reason) for every call edge leaving `source`.
+fn calls<'a>(model: &'a Building, source: &Node) -> Vec<(&'a Node, Option<String>)> {
+    model
+        .edges
+        .iter()
+        .filter(|e| e.kind == EdgeKind::Calls && e.source == source.id)
+        .map(|e| {
+            let target = model.nodes.iter().find(|n| n.id == e.target).unwrap();
+            let reason = e
+                .attributes
+                .get("source.unresolved-reason")
+                .and_then(|v| v.as_str())
+                .map(str::to_owned);
+            (target, reason)
+        })
+        .collect()
+}
+
+fn single_call<'a>(model: &'a Building, source: &Node) -> (&'a Node, Option<String>) {
+    let mut found = calls(model, source);
+    assert_eq!(found.len(), 1, "calls from {}", source.name);
+    found.remove(0)
+}
+
+#[test]
+fn header_prototype_resolves_to_the_paired_definition_across_files() {
+    let model = scan_files(&[
+        ("src/util.h", "int helper(int x);\n"),
+        (
+            "src/util.cpp",
+            "#include \"util.h\"\nint helper(int x) { return x; }\n",
+        ),
+        (
+            "src/main.cpp",
+            "#include \"util.h\"\nint main() { return helper(1); }\n",
+        ),
+        // A second program's same-named definition never includes util.h.
+        ("tools/dup.cpp", "int helper(int x) { return x + 1; }\n"),
+    ]);
+    let (target, reason) = single_call(&model, function(&model, "src/main.cpp", "main"));
+    assert_eq!(target.path.as_deref(), Some("src/util.cpp"));
+    assert_eq!(reason, None);
+    let dup = function(&model, "tools/dup.cpp", "helper");
+    assert!(
+        !model
+            .edges
+            .iter()
+            .any(|e| e.kind == EdgeKind::Calls && e.target == dup.id)
+    );
+}
+
+#[test]
+fn undeclared_and_internal_definitions_in_other_files_stay_unresolved() {
+    let model = scan_files(&[
+        (
+            "src/util.cpp",
+            "static int twice(int x) { return 2 * x; }\nint helper(int x) { return twice(x); }\n",
+        ),
+        (
+            "src/other.cpp",
+            "static int twice(int x) { return x + x; }\nint local() { return twice(1); }\nint caller() { return helper(1); }\n",
+        ),
+    ]);
+    let (local, _) = single_call(&model, function(&model, "src/other.cpp", "local"));
+    assert_eq!(local.path.as_deref(), Some("src/other.cpp"));
+    assert_eq!(
+        local
+            .attributes
+            .get("source.linkage")
+            .and_then(|v| v.as_str()),
+        Some("internal")
+    );
+    let (helper, _) = single_call(&model, function(&model, "src/util.cpp", "helper"));
+    assert_eq!(helper.path.as_deref(), Some("src/util.cpp"));
+    // No prototype for helper is visible from other.cpp.
+    let (target, reason) = single_call(&model, function(&model, "src/other.cpp", "caller"));
+    assert_eq!(target.kind, NodeKind::External);
+    assert_eq!(reason.as_deref(), Some("not-visible"));
+}
+
+#[test]
+fn out_of_line_methods_use_leaf_names_and_resolve_implicit_and_explicit_this() {
+    let model = scan_files(&[
+        (
+            "include/geo/shape.h",
+            "namespace geo {\nclass Shape {\npublic:\n  double area() const;\n  int& counter();\nprivate:\n  double scale(double x) const;\n};\n}\n",
+        ),
+        (
+            "src/shape.cpp",
+            "#include \"geo/shape.h\"\nnamespace geo {\ndouble Shape::area() const {\n  return this->scale(2.0)\n    + scale(1.0);\n}\ndouble Shape::scale(double x) const { return x; }\nint& Shape::counter() { static int n = 0; return n; }\n}\n",
+        ),
+    ]);
+    let area = function(&model, "src/shape.cpp", "area");
+    assert_eq!(
+        area.attributes
+            .get("source.qualifier")
+            .and_then(|v| v.as_str()),
+        Some("Shape")
+    );
+    assert_eq!(
+        area.attributes
+            .get("source.qualified-name")
+            .and_then(|v| v.as_str()),
+        Some("geo::Shape::area")
+    );
+    // Both call lines merge into one edge with two pieces of provenance.
+    let (scale, reason) = single_call(&model, area);
+    assert_eq!(scale.name, "scale");
+    assert_eq!(scale.path.as_deref(), Some("src/shape.cpp"));
+    assert_eq!(reason, None);
+    let edge = model
+        .edges
+        .iter()
+        .find(|e| e.source == area.id && e.target == scale.id)
+        .unwrap();
+    assert_eq!(edge.evidence.len(), 2);
+    // A reference return type no longer leaks into the declaration name.
+    function(&model, "src/shape.cpp", "counter");
+}
+
+#[test]
+fn macro_ambiguous_external_and_untyped_receivers_are_classified_not_guessed() {
+    let model = scan_files(&[
+        ("src/log.h", "#define LOG_TWICE(x) ((x) * 2)\n"),
+        (
+            "src/main.cpp",
+            "#include \"log.h\"\n#include <string>\nstruct Box { int size() { return 1; } };\nBox make();\nvoid emit(int) {}\nvoid emit(double) {}\nint main() {\n  std::string text;\n  emit(1);\n  text.size();\n  make().size();\n  return static_cast<int>(LOG_TWICE(2));\n}\n",
+        ),
+    ]);
+    let main = function(&model, "src/main.cpp", "main");
+    let mut reasons: Vec<_> = calls(&model, main)
+        .into_iter()
+        .map(|(target, reason)| {
+            assert_eq!(target.kind, NodeKind::External);
+            (target.name.clone(), reason.unwrap())
+        })
+        .collect();
+    reasons.sort();
+    assert_eq!(
+        reasons,
+        [
+            ("LOG_TWICE".to_owned(), "macro".to_owned()),
+            ("emit".to_owned(), "ambiguous".to_owned()),
+            ("make".to_owned(), "declared-only".to_owned()),
+            ("size".to_owned(), "receiver-type-external".to_owned()),
+            ("size".to_owned(), "receiver-type-unknown".to_owned()),
+        ]
+    );
+}
+
+#[test]
+fn declared_receivers_fields_and_bases_resolve_members_with_a_label() {
+    let model = scan_files(&[
+        (
+            "src/shape.h",
+            "#include <memory>\nstruct Base { int id() const; };\nstruct Shape : Base {\n  int area() const;\n  int total();\n  std::unique_ptr<Shape> next_;\n  Shape* raw_;\n};\n",
+        ),
+        (
+            "src/shape.cpp",
+            "#include \"shape.h\"\nint Base::id() const { return 0; }\nint Shape::area() const { return id(); }\nint Shape::total() {\n  return next_->area()\n    + this->raw_->area();\n}\n",
+        ),
+        (
+            "src/main.cpp",
+            "#include \"shape.h\"\nint use(const Shape& ref, Shape* ptr) {\n  auto owned = std::make_unique<Shape>();\n  return ref.area()\n    + ptr->id()\n    + owned->area();\n}\n",
+        ),
+    ]);
+    let targets = |source: &Node| {
+        let mut found: Vec<_> = calls(&model, source)
+            .into_iter()
+            .filter(|(target, _)| !target.name.starts_with("std::"))
+            .map(|(target, reason)| {
+                assert_eq!(reason, None, "{} -> {}", source.name, target.name);
+                (target.path.clone().unwrap(), target.name.clone())
+            })
+            .collect();
+        found.sort();
+        found.dedup();
+        found
+    };
+    let area = ("src/shape.cpp".to_owned(), "area".to_owned());
+    let id = ("src/shape.cpp".to_owned(), "id".to_owned());
+    assert_eq!(
+        targets(function(&model, "src/main.cpp", "use")),
+        [area.clone(), id.clone()]
+    );
+    assert_eq!(
+        targets(function(&model, "src/shape.cpp", "total")),
+        std::slice::from_ref(&area)
+    );
+    // Unqualified lookup inside a class scope reaches in-repository bases.
+    assert_eq!(targets(function(&model, "src/shape.cpp", "area")), [id]);
+    let use_fn = function(&model, "src/main.cpp", "use");
+    assert!(
+        model
+            .edges
+            .iter()
+            .filter(|e| e.kind == EdgeKind::Calls && e.source == use_fn.id)
+            .filter(|e| model
+                .nodes
+                .iter()
+                .any(|n| n.id == e.target && n.kind == NodeKind::Function))
+            .all(|e| e
+                .attributes
+                .get("source.resolution")
+                .and_then(|v| v.as_str())
+                == Some("declared-receiver-type"))
+    );
+}
+
+#[test]
+fn conversion_operators_are_declarations_matching_their_prototypes() {
+    let model = scan_files(&[(
+        "src/flag.cpp",
+        "struct Flag {\n  explicit operator bool() const;\n};\nFlag::operator bool() const { return true; }\n",
+    )]);
+    let operator = function(&model, "src/flag.cpp", "operator bool");
+    assert_eq!(
+        operator
+            .attributes
+            .get("source.qualified-name")
+            .and_then(|v| v.as_str()),
+        Some("Flag::operator bool")
+    );
+}
+
+#[test]
+fn resolution_metrics_count_call_sites_by_outcome() {
+    let model = scan_files(&[(
+        "src/main.cpp",
+        "struct Box { int get() { return 1; } };\nBox make();\nint one() { return 1; }\nint main() {\n  return one()\n    + one()\n    + make().get();\n}\n",
+    )]);
+    let cpp = &model.metrics.resolution["cpp"];
+    assert_eq!(cpp.call_site_count, 4);
+    assert_eq!(cpp.resolved_call_site_count, 2);
+    assert_eq!(
+        cpp.unresolved_call_sites_by_reason["receiver-type-unknown"],
+        1
+    );
+    assert_eq!(cpp.unresolved_call_sites_by_reason["declared-only"], 1);
+    assert_eq!(cpp.function_count, 3);
+    // main has no callers and Box::get is only reachable through an untyped receiver.
+    assert_eq!(cpp.functions_without_resolved_callers, 2);
+}
+
+#[test]
+fn using_directives_and_declarations_extend_lookup_only_where_visible() {
+    let model = scan_files(&[
+        (
+            "include/lib/tune.h",
+            "namespace lib::daemon {\nstruct Tune { static int ticks(); };\nint helper();\n}\n",
+        ),
+        (
+            "src/tune.cpp",
+            "#include \"lib/tune.h\"\nnamespace lib::daemon {\nint Tune::ticks() { return 1; }\nint helper() { return 2; }\n}\n",
+        ),
+        (
+            "tests/tune_test.cpp",
+            "#include \"lib/tune.h\"\nusing namespace lib::daemon;\nint check() {\n  Tune tune;\n  return Tune::ticks()\n    + tune.ticks();\n}\n",
+        ),
+        (
+            "tests/alias_test.cpp",
+            "#include \"lib/tune.h\"\nusing lib::daemon::helper;\nint alias() { return helper(); }\n",
+        ),
+        // Clean negative: the directive lives in a file this caller never includes.
+        ("tests/other_using.cpp", "using namespace lib::daemon;\n"),
+        (
+            "tests/negative_test.cpp",
+            "#include \"lib/tune.h\"\nint negative() { return helper(); }\n",
+        ),
+    ]);
+    let (ticks, reason) = single_call(&model, function(&model, "tests/tune_test.cpp", "check"));
+    assert_eq!(ticks.path.as_deref(), Some("src/tune.cpp"));
+    assert_eq!(ticks.name, "ticks");
+    assert_eq!(reason, None);
+    let (helper, reason) = single_call(&model, function(&model, "tests/alias_test.cpp", "alias"));
+    assert_eq!(helper.path.as_deref(), Some("src/tune.cpp"));
+    assert_eq!(reason, None);
+    let (target, reason) = single_call(
+        &model,
+        function(&model, "tests/negative_test.cpp", "negative"),
+    );
+    assert_eq!(target.kind, NodeKind::External);
+    assert_eq!(reason.as_deref(), Some("not-visible"));
+}
+
+#[test]
+fn brace_default_arguments_do_not_hide_prototypes_or_report_errors() {
+    let model = scan_files(&[
+        (
+            "src/api.h",
+            "struct Config {};\nint store(const Config& config = {});\n",
+        ),
+        (
+            "src/api.cpp",
+            "#include \"api.h\"\nint store(const Config& config) { return 0; }\n",
+        ),
+        (
+            "src/main.cpp",
+            "#include \"api.h\"\nint main() { return store(); }\n",
+        ),
+    ]);
+    let (target, reason) = single_call(&model, function(&model, "src/main.cpp", "main"));
+    assert_eq!(target.path.as_deref(), Some("src/api.cpp"));
+    assert_eq!(reason, None);
+    assert!(model.diagnostics.is_empty(), "{:?}", model.diagnostics);
+}

tests/fixtures/cpp_xtu/cpp/include/geo/shape.h

@@ -0,0 +1,21 @@
+#pragma once
+
+namespace geo {
+class Shape {
+public:
+    Shape();
+    double area() const;
+    static Shape unit();
+    int& counter();
+
+private:
+    double scale(double x) const;
+};
+
+class Circle : public Shape {
+public:
+    double radius() const;
+};
+
+double total(const Shape& shape);
+}  // namespace geo

tests/fixtures/cpp_xtu/cpp/labels.json

@@ -0,0 +1,223 @@
+{
+  "language_prefixes": {
+    "headers": "include/",
+    "sources": "src/",
+    "tools": "tools/"
+  },
+  "symbols": [
+    [
+      "include/geo/shape.h::scope=geo::Shape",
+      "class"
+    ],
+    [
+      "src/shape.cpp::scope=geo::Shape::Shape",
+      "function"
+    ],
+    [
+      "src/shape.cpp::scope=geo::Shape::area",
+      "function"
+    ],
+    [
+      "src/shape.cpp::scope=geo::Shape::scale",
+      "function"
+    ],
+    [
+      "src/shape.cpp::scope=geo::Shape::unit",
+      "function"
+    ],
+    [
+      "src/shape.cpp::scope=geo::Shape::counter",
+      "function"
+    ],
+    [
+      "src/shape.cpp::scope=geo::total",
+      "function"
+    ],
+    [
+      "src/util.cpp::twice",
+      "function"
+    ],
+    [
+      "src/util.cpp::helper",
+      "function"
+    ],
+    [
+      "src/main.cpp::main",
+      "function"
+    ],
+    [
+      "src/other.cpp::twice",
+      "function"
+    ],
+    [
+      "src/other.cpp::orphan",
+      "function"
+    ],
+    [
+      "src/other.cpp::undeclared_caller",
+      "function"
+    ],
+    [
+      "src/overload.cpp::log_value",
+      "function"
+    ],
+    [
+      "src/overload.cpp::log_value",
+      "function"
+    ],
+    [
+      "src/overload.cpp::use_log",
+      "function"
+    ],
+    [
+      "src/legacy.c::add",
+      "function"
+    ],
+    [
+      "src/legacy.c::legacy_sum",
+      "function"
+    ],
+    [
+      "tools/dup.cpp::helper",
+      "function"
+    ],
+    [
+      "include/geo/shape.h::scope=geo::Circle",
+      "class"
+    ],
+    [
+      "src/shape.cpp::scope=geo::Circle::radius",
+      "function"
+    ],
+    [
+      "src/buffer.h::Buffer",
+      "class"
+    ],
+    [
+      "src/buffer.h::Buffer::size",
+      "function"
+    ]
+  ],
+  "relationships": [
+    [
+      "src/shape.cpp",
+      "imports",
+      "include/geo/shape.h"
+    ],
+    [
+      "src/util.cpp",
+      "imports",
+      "src/util.h"
+    ],
+    [
+      "src/main.cpp",
+      "imports",
+      "include/geo/shape.h"
+    ],
+    [
+      "src/main.cpp",
+      "imports",
+      "src/util.h"
+    ],
+    [
+      "src/shape.cpp::scope=geo::Shape::area",
+      "calls",
+      "src/shape.cpp::scope=geo::Shape::scale"
+    ],
+    [
+      "src/shape.cpp::scope=geo::Shape::unit",
+      "calls",
+      "src/shape.cpp::scope=geo::Shape::Shape"
+    ],
+    [
+      "src/util.cpp::helper",
+      "calls",
+      "src/util.cpp::twice"
+    ],
+    [
+      "src/main.cpp::main",
+      "calls",
+      "src/shape.cpp::scope=geo::Shape::unit"
+    ],
+    [
+      "src/main.cpp::main",
+      "calls",
+      "src/util.cpp::helper"
+    ],
+    [
+      "src/main.cpp::main",
+      "calls",
+      "src/shape.cpp::scope=geo::total"
+    ],
+    [
+      "src/main.cpp::main",
+      "calls",
+      "external:cpp:LOG_TWICE"
+    ],
+    [
+      "src/other.cpp::orphan",
+      "calls",
+      "src/other.cpp::twice"
+    ],
+    [
+      "src/other.cpp::undeclared_caller",
+      "calls",
+      "external:cpp:helper"
+    ],
+    [
+      "src/overload.cpp::use_log",
+      "calls",
+      "external:cpp:log_value"
+    ],
+    [
+      "src/legacy.c::legacy_sum",
+      "calls",
+      "src/legacy.c::add"
+    ],
+    [
+      "src/main.cpp",
+      "imports",
+      "src/buffer.h"
+    ],
+    [
+      "src/main.cpp",
+      "imports",
+      "external:cpp:string"
+    ],
+    [
+      "include/geo/shape.h::scope=geo::Circle",
+      "inherits",
+      "include/geo/shape.h::scope=geo::Shape"
+    ],
+    [
+      "src/shape.cpp::scope=geo::Circle::radius",
+      "calls",
+      "src/shape.cpp::scope=geo::Shape::area"
+    ],
+    [
+      "src/shape.cpp::scope=geo::total",
+      "calls",
+      "src/shape.cpp::scope=geo::Shape::area"
+    ],
+    [
+      "src/main.cpp::main",
+      "calls",
+      "src/shape.cpp::scope=geo::Shape::counter"
+    ],
+    [
+      "src/main.cpp::main",
+      "calls",
+      "external:cpp:size"
+    ],
+    [
+      "src/main.cpp::main",
+      "calls",
+      "external:cpp:size"
+    ],
+    [
+      "src/main.cpp::main",
+      "calls",
+      "external:cpp:make_buffer"
+    ]
+  ]
+}

tests/fixtures/cpp_xtu/cpp/src/buffer.h

@@ -0,0 +1,6 @@
+#pragma once
+
+// Clean negative: a repository size() that std::string and untyped receivers must not reach.
+struct Buffer {
+    int size() const { return 0; }
+};

tests/fixtures/cpp_xtu/cpp/src/legacy.c

@@ -0,0 +1,3 @@
+static int add(int a, int b) { return a + b; }
+
+int legacy_sum(void) { return add(1, 2); }

tests/fixtures/cpp_xtu/cpp/src/main.cpp

@@ -0,0 +1,16 @@
+#include "geo/shape.h"
+#include "buffer.h"
+#include "util.h"
+#include <string>
+
+Buffer make_buffer();
+
+int main() {
+    std::string text;
+    text.size();
+    make_buffer().size();
+    geo::Shape shape = geo::Shape::unit();
+    int n = helper(3);
+    shape.counter();
+    return static_cast<int>(geo::total(shape)) + n + LOG_TWICE(n);
+}

tests/fixtures/cpp_xtu/cpp/src/other.cpp

@@ -0,0 +1,6 @@
+// Clean negative: same-named internal function and an undeclared cross-TU call.
+static int twice(int x) { return x + x; }
+
+int orphan() { return twice(1); }
+
+int undeclared_caller() { return helper(1); }

tests/fixtures/cpp_xtu/cpp/src/overload.cpp

@@ -0,0 +1,4 @@
+void log_value(int) {}
+void log_value(double) {}
+
+void use_log() { log_value(1); }

tests/fixtures/cpp_xtu/cpp/src/shape.cpp

@@ -0,0 +1,20 @@
+#include "geo/shape.h"
+
+namespace geo {
+Shape::Shape() {}
+
+double Shape::area() const { return this->scale(2.0) + scale(1.0); }
+
+double Shape::scale(double x) const { return x; }
+
+Shape Shape::unit() { return Shape(); }
+
+int& Shape::counter() {
+    static int count = 0;
+    return count;
+}
+
+double Circle::radius() const { return area(); }
+
+double total(const Shape& shape) { return shape.area(); }
+}  // namespace geo

tests/fixtures/cpp_xtu/cpp/src/util.cpp

@@ -0,0 +1,5 @@
+#include "util.h"
+
+static int twice(int x) { return x * 2; }
+
+int helper(int x) { return twice(x); }

tests/fixtures/cpp_xtu/cpp/src/util.h

@@ -0,0 +1,4 @@
+#pragma once
+
+int helper(int x);
+#define LOG_TWICE(x) ((x) * 2)

tests/fixtures/cpp_xtu/cpp/tools/dup.cpp

@@ -0,0 +1,2 @@
+// Clean negative: a second program's helper that never includes util.h.
+int helper(int x) { return x; }

tests/fixtures/rust_methods/rust/labels.json

@@ -0,0 +1,51 @@
+{
+  "language_prefixes": {"rust": "src/"},
+  "symbols": [
+    ["src/lib.rs::run", "function"],
+    ["src/lib.rs::describe", "function"],
+    ["src/store.rs::Engine", "class"],
+    ["src/store.rs::Engine::commit", "function"],
+    ["src/store.rs::Store", "class"],
+    ["src/store.rs::Store::open", "function"],
+    ["src/store.rs::Store::build", "function"],
+    ["src/store.rs::Store::flush", "function"],
+    ["src/store.rs::Store::name", "function"],
+    ["src/store.rs::Store::is_ready", "function"],
+    ["src/store.rs::Store::log", "function"],
+    ["src/store.rs::Named", "class"],
+    ["src/store.rs::Named::label", "function"],
+    ["src/store.rs::Store::label", "function"],
+    ["src/store.rs::Engine::label", "function"],
+    ["src/store.rs::show", "function"],
+    ["src/store.rs::show_generic", "function"],
+    ["src/negative.rs::File", "class"],
+    ["src/negative.rs::File::open", "function"],
+    ["src/negative.rs::File::sync_all", "function"],
+    ["src/negative.rs::unrelated", "function"]
+  ],
+  "relationships": [
+    ["src/lib.rs", "imports", "src/store.rs"],
+    ["src/lib.rs", "imports", "external:rust:std::fs::File"],
+    ["src/store.rs", "imports", "external:rust:std::sync::Arc"],
+    ["src/lib.rs::run", "calls", "src/store.rs::Store::open"],
+    ["src/lib.rs::run", "calls", "src/store.rs::Store::flush"],
+    ["src/lib.rs::run", "calls", "src/store.rs::Store::is_ready"],
+    ["src/lib.rs::run", "calls", "src/lib.rs::describe"],
+    ["src/lib.rs::run", "calls", "external:rust:File::open"],
+    ["src/lib.rs::run", "calls", "external:rust:sync_all"],
+    ["src/lib.rs::run", "calls", "external:rust:Ok"],
+    ["src/lib.rs::describe", "calls", "src/store.rs::Store::name"],
+    ["src/store.rs::Store::open", "calls", "external:rust:Ok"],
+    ["src/store.rs::Store::open", "calls", "src/store.rs::Store::build"],
+    ["src/store.rs::Store::build", "calls", "external:rust:Arc::new"],
+    ["src/store.rs::Store::build", "calls", "external:rust:into"],
+    ["src/store.rs::Store::flush", "calls", "src/store.rs::Engine::commit"],
+    ["src/store.rs::Store::flush", "calls", "src/store.rs::Store::log"],
+    ["src/store.rs::Store::label", "calls", "src/store.rs::Store::name"],
+    ["src/store.rs::Store::label", "calls", "external:rust:to_owned"],
+    ["src/store.rs::Engine::label", "calls", "external:rust:String::new"],
+    ["src/store.rs::show", "calls", "src/store.rs::Named::label"],
+    ["src/store.rs::show_generic", "calls", "external:rust:label"],
+    ["src/negative.rs::unrelated", "calls", "external:rust:len"]
+  ]
+}

tests/fixtures/rust_methods/rust/src/lib.rs

@@ -0,0 +1,19 @@
+mod negative;
+mod store;
+
+use crate::store::Store;
+use std::fs::File;
+
+pub fn run(path: &str) -> anyhow::Result<()> {
+    let store = Store::open(path)?;
+    store.flush();
+    assert!(store.is_ready(), "not ready: {}", describe(&store));
+    // Clean negative: std's File must not reach the repository's negative::File.
+    let file = File::open(path)?;
+    file.sync_all()?;
+    Ok(())
+}
+
+fn describe(store: &Store) -> String {
+    format!("{}", store.name())
+}

tests/fixtures/rust_methods/rust/src/negative.rs

@@ -0,0 +1,14 @@
+// Clean negative: same names as std::fs::File; nothing in lib.rs may call these.
+pub struct File;
+
+impl File {
+    pub fn open(_path: &str) -> Self {
+        File
+    }
+
+    pub fn sync_all(&self) {}
+}
+
+pub fn unrelated(value: &str) -> usize {
+    value.len()
+}

tests/fixtures/rust_methods/rust/src/store.rs

@@ -0,0 +1,65 @@
+use std::sync::Arc;
+
+pub struct Engine;
+
+impl Engine {
+    pub fn commit(&self) {}
+}
+
+pub struct Store {
+    inner: Arc<Engine>,
+    name: String,
+}
+
+impl Store {
+    pub fn open(path: &str) -> anyhow::Result<Self> {
+        Ok(Self::build(path))
+    }
+
+    fn build(path: &str) -> Self {
+        Store {
+            inner: Arc::new(Engine),
+            name: path.into(),
+        }
+    }
+
+    pub fn flush(&self) {
+        self.inner.commit();
+        self.log();
+    }
+
+    pub fn name(&self) -> &str {
+        &self.name
+    }
+
+    pub fn is_ready(&self) -> bool {
+        true
+    }
+
+    fn log(&self) {}
+}
+
+pub trait Named {
+    fn label(&self) -> String;
+}
+
+impl Named for Store {
+    fn label(&self) -> String {
+        self.name().to_owned()
+    }
+}
+
+impl Named for Engine {
+    fn label(&self) -> String {
+        String::new()
+    }
+}
+
+pub fn show(item: &dyn Named) -> String {
+    item.label()
+}
+
+// Clean negative: a generic receiver names no concrete implementation.
+pub fn show_generic<T: Named>(item: &T) -> String {
+    item.label()
+}

tests/rust_methods.rs

@@ -0,0 +1,155 @@
+use brick::model::{Building, EdgeKind, Node, NodeKind};
+use brick::scan;
+use std::fs;
+
+fn scan_files(files: &[(&str, &str)]) -> Building {
+    let root = tempfile::tempdir().unwrap();
+    for (path, content) in files {
+        let file = root.path().join(path);
+        fs::create_dir_all(file.parent().unwrap()).unwrap();
+        fs::write(file, content).unwrap();
+    }
+    scan::scan(root.path()).unwrap()
+}
+
+fn function<'a>(model: &'a Building, path: &str, name: &str) -> &'a Node {
+    model
+        .nodes
+        .iter()
+        .find(|n| n.kind == NodeKind::Function && n.path.as_deref() == Some(path) && n.name == name)
+        .unwrap_or_else(|| panic!("missing {path}::{name}"))
+}
+
+/// (target parent name, target name, attribute value) for calls leaving `source`.
+fn calls(model: &Building, source: &Node, attribute: &str) -> Vec<(String, String, String)> {
+    let mut found: Vec<_> = model
+        .edges
+        .iter()
+        .filter(|e| e.kind == EdgeKind::Calls && e.source == source.id)
+        .map(|e| {
+            let target = model.nodes.iter().find(|n| n.id == e.target).unwrap();
+            let parent = target
+                .parent
+                .as_ref()
+                .and_then(|id| model.nodes.iter().find(|n| &n.id == id))
+                .map(|n| n.name.clone())
+                .unwrap_or_default();
+            let value = e
+                .attributes
+                .get(attribute)
+                .and_then(|v| v.as_str())
+                .unwrap_or("")
+                .to_owned();
+            (parent, target.name.clone(), value)
+        })
+        .collect();
+    found.sort();
+    found
+}
+
+#[test]
+fn expression_macro_bodies_yield_calls_and_other_macros_stay_opaque() {
+    let model = scan_files(&[(
+        "src/lib.rs",
+        "fn check() -> bool { true }\nfn name() -> u8 { 0 }\nfn hidden() {}\nmacro_rules! custom { ($e:expr) => { $e } }\nfn run() {\n    assert!(check(), \"{}\", format!(\"{}\", name()));\n    custom!(hidden());\n}\n",
+    )]);
+    let run = function(&model, "src/lib.rs", "run");
+    assert_eq!(
+        calls(&model, run, "source.extraction"),
+        [
+            ("lib.rs".into(), "check".into(), "macro-reparse".into()),
+            ("lib.rs".into(), "name".into(), "macro-reparse".into()),
+        ]
+    );
+    let hidden = function(&model, "src/lib.rs", "hidden");
+    assert!(
+        !model
+            .edges
+            .iter()
+            .any(|e| e.target == hidden.id && e.kind == EdgeKind::Calls)
+    );
+}
+
+#[test]
+fn receivers_resolve_through_self_fields_constructors_and_dyn_traits() {
+    let model = scan_files(&[(
+        "src/lib.rs",
+        "use std::sync::Arc;\npub struct Engine;\nimpl Engine { pub fn commit(&self) {} }\npub trait Named { fn label(&self) -> String; }\npub struct Store { inner: Arc<Engine> }\nimpl Store {\n    pub fn open() -> Result<Self, ()> { Ok(Self::build()) }\n    fn build() -> Self { Store { inner: Arc::new(Engine) } }\n    fn flush(&self) {\n        self.inner.commit();\n        self.log();\n    }\n    fn log(&self) {}\n}\nfn run(item: &dyn Named) -> Result<(), ()> {\n    let store = Store::open()?;\n    store.flush();\n    item.label();\n    Ok(())\n}\n",
+    )]);
+    let resolved = |source: &Node| {
+        calls(&model, source, "source.resolution")
+            .into_iter()
+            .filter(|(parent, _, _)| !parent.is_empty())
+            .collect::<Vec<_>>()
+    };
+    assert_eq!(
+        resolved(function(&model, "src/lib.rs", "flush")),
+        [
+            (
+                "Engine".into(),
+                "commit".into(),
+                "declared-receiver-type".into()
+            ),
+            ("Store".into(), "log".into(), "self-receiver".into()),
+        ]
+    );
+    assert_eq!(
+        resolved(function(&model, "src/lib.rs", "open")),
+        [("Store".into(), "build".into(), "impl-type".into())]
+    );
+    assert_eq!(
+        resolved(function(&model, "src/lib.rs", "run")),
+        [
+            (
+                "Named".into(),
+                "label".into(),
+                "declared-receiver-type".into()
+            ),
+            (
+                "Store".into(),
+                "flush".into(),
+                "declared-receiver-type".into()
+            ),
+            // Same-file `Type::f` already resolves by qualified lookup, unlabeled.
+            ("Store".into(), "open".into(), "".into()),
+        ]
+    );
+}
+
+#[test]
+fn foreign_imports_generics_and_competing_trait_impls_never_guess() {
+    let model = scan_files(&[
+        (
+            "src/lib.rs",
+            "mod local;\nuse std::fs::File;\npub trait Named { fn label(&self) -> String; }\nstruct A;\nstruct B;\nstruct C;\nimpl Named for A { fn label(&self) -> String { String::new() } }\nimpl Named for C { fn label(&self) -> String { String::new() } }\ntrait Other { fn label(&self) -> String; }\nimpl Other for A { fn label(&self) -> String { String::new() } }\nfn run<T: Named>(generic: &T, a: A) {\n    let file = File::open(\"x\").unwrap();\n    file.sync_all();\n    generic.label();\n    a.label();\n}\n",
+        ),
+        (
+            "src/local.rs",
+            "pub struct File;\nimpl File {\n    pub fn open(_p: &str) -> Self { File }\n    pub fn sync_all(&self) {}\n}\n",
+        ),
+    ]);
+    let run = function(&model, "src/lib.rs", "run");
+    let reasons: Vec<_> = calls(&model, run, "source.unresolved-reason")
+        .into_iter()
+        .map(|(_, name, reason)| (name, reason))
+        .collect();
+    assert_eq!(
+        reasons,
+        [
+            ("File::open".into(), "qualifier-unknown".into()),
+            ("label".into(), "ambiguous".into()),
+            ("label".into(), "receiver-type-unknown".into()),
+            ("sync_all".into(), "receiver-type-unknown".into()),
+            ("unwrap".into(), "receiver-type-unknown".into()),
+        ]
+    );
+    for name in ["open", "sync_all"] {
+        let local = function(&model, "src/local.rs", name);
+        assert!(
+            !model
+                .edges
+                .iter()
+                .any(|e| e.target == local.id && e.kind == EdgeKind::Calls)
+        );
+    }
+}