diff --git a/src/openultrasast/model/partitions.py b/src/openultrasast/model/partitions.py
index f6099b7..b3043cd 100644
--- a/src/openultrasast/model/partitions.py
+++ b/src/openultrasast/model/partitions.py
@@ -51,6 +51,10 @@ class PartitionGraph:
         self.path_languages: dict[str, str] = {}
         self.partitions: tuple[PartitionCoverage, ...] = ()
         self.boundaries: tuple[str, ...] = ()
+        # What each boundary is ABOUT, where that is known: the paths a symlink boundary skipped (a directory
+        # ends in `/`) and the languages no frontend reads. A boundary absent from both reaches everything.
+        self.boundary_paths: dict[str, tuple[str, ...]] = {}
+        self.boundary_languages: dict[str, tuple[str, ...]] = {}
         self.unparsed: tuple[str, ...] = ()
         self.cpg_path = Path("partitioned-cpg")
 
@@ -167,6 +171,8 @@ def build_partitions(
     graph = PartitionGraph(budget)
     paths: dict[str, list[Path]] = {}
     boundaries: set[str] = set()
+    owned_paths: dict[str, set[str]] = {}
+    owned_languages: dict[str, set[str]] = {}
     excluded: set[str] = set()
     facts = layout_facts()
     root_fd = os.open(root, os.O_RDONLY | os.O_DIRECTORY | os.O_NOFOLLOW)
@@ -192,6 +198,8 @@ def build_partitions(
                 if path.is_symlink() or is_vendored(relative + "/", facts):
                     excluded.add(relative + "/")
                     boundaries.add("symlink_context_unresolved" if path.is_symlink() else "vendor_semantics_unresolved")
+                    if path.is_symlink():
+                        owned_paths.setdefault("symlink_context_unresolved", set()).add(relative + "/")
                     dirs.remove(name)
             for name in files:
                 if budget is not None and time.monotonic() >= budget.deadline_monotonic:
@@ -206,6 +214,7 @@ def build_partitions(
                 if path.is_symlink() or not path.is_file():
                     excluded.add(relative)
                     boundaries.add("symlink_context_unresolved")
+                    owned_paths.setdefault("symlink_context_unresolved", set()).add(relative)
                     continue
                 language = LANGUAGE_BY_EXTENSION.get(path.suffix.lower(), "unknown")
                 if language == "unknown":
@@ -234,6 +243,7 @@ def build_partitions(
             if frontend is None:
                 records.append(PartitionCoverage(language, None, relative_paths, 0, "unsupported", ("frontend_unsupported",)))
                 boundaries.add("frontend_unsupported")
+                owned_languages.setdefault("frontend_unsupported", set()).add(language)
                 continue
             scratch = Path(tempfile.mkdtemp(prefix="ousast-input-"))
             graph.roots[language] = scratch
@@ -283,6 +293,8 @@ def build_partitions(
             for record in records
         )
         graph.boundaries = tuple(sorted(boundaries))
+        graph.boundary_paths = {reason: tuple(sorted(paths)) for reason, paths in owned_paths.items()}
+        graph.boundary_languages = {reason: tuple(sorted(languages)) for reason, languages in owned_languages.items()}
         return graph
     except BaseException:
         graph.cleanup()
diff --git a/src/openultrasast/model/scan.py b/src/openultrasast/model/scan.py
index 14cd446..668f0e9 100644
--- a/src/openultrasast/model/scan.py
+++ b/src/openultrasast/model/scan.py
@@ -247,7 +247,7 @@ def _scan_repository_impl(
             execution_budget,
             {path: tuple(sorted(languages)) for path, languages in declarations.items()},
         )
-        degradations.extend({"stage": "model", "reason": reason} for reason in cpg.boundaries)
+        degradations.extend(_boundary_degradations(cpg))
     else:
         cpg = _build(backend, root, dominant, execution_budget=execution_budget)
     build_seconds = round(time.monotonic() - build_started, 2)
@@ -287,7 +287,14 @@ def _scan_repository_impl(
     if getattr(cpg, "unparsed", ()):  # a backend need not carry the field
         unparsed = tuple(cpg.unparsed)
         degradations.append(
-            {"stage": "model", "reason": "files_unparsed", "count": len(unparsed), "files": [Path(name).name for name in unparsed[:20]]}
+            {
+                "stage": "model",
+                "reason": "files_unparsed",
+                "count": len(unparsed),
+                "files": [Path(name).name for name in unparsed[:20]],
+                # Whole, so the gap can be owned by exactly these files.
+                "owned_paths": [str(name).removeprefix("./") for name in unparsed],
+            }
         )
 
     # Count calls here rather than reading a client's own meter: the budget is this driver's contract and
@@ -590,25 +597,31 @@ def _scan_repository_impl(
     # rule is now written in the design: a gap is owned by the narrowest scope that caused it.
     scoped_graph_gaps: dict[str, list[str]] = {}
     unscoped_graph_gaps: list[str] = []
-    # A census gap that NAMES its missing files is owned by those files. The first evaluation on untouched
-    # code (benchmarks/independent/results-v1.json) completed no question at all on eight of eleven projects,
-    # and on the ones traced the cause was this: `.eslintrc.js` and `webpack.config.js` absent from a
-    # JavaScript graph, a `contrib/apache/api.wsgi` shim absent from a Python graph, and every question of that
-    # language marked unresolved. A missing file makes the graph incomplete ABOUT that file; an answer about
-    # another file is still an answer, and the gap stays in the report as a boundary. A gap that names no files
-    # keeps its partition-wide reach, and one that names no partition reaches everything, as before.
-    file_owned_gaps: dict[str, set[str]] = {}
+    # A gap that NAMES what it is about is owned by exactly that. The first evaluation on untouched code
+    # (benchmarks/independent/results-v1.json) completed no question at all on eight of eleven projects, and
+    # the traced causes all had this shape: `.eslintrc.js` missing from a JavaScript graph, one symlinked
+    # `app.wsgi` that is not even source, one unparsed file, a Go directory in a Python project -- and every
+    # question of the language, or of the repository, marked unresolved. A missing, skipped or unparsed file
+    # makes the graph incomplete ABOUT that file (a skipped directory, about what is under it); a language no
+    # frontend reads, about that language. An answer about anything else is still an answer, and every gap
+    # stays in the report as a boundary. A gap that names nothing reaches its partition, or everything.
+    path_owned_gaps: set[str] = set()
     for item in degradations:
         if item.get("reason") not in GRAPH_INTEGRITY_GAPS:
             continue
         partition = str(item.get("census_language") or "")
-        absent_files = item.get("missing_file_names")
-        if partition and isinstance(absent_files, list) and absent_files and all(isinstance(name, str) for name in absent_files):
-            file_owned_gaps.setdefault(partition, set()).update(name.removeprefix("./") for name in absent_files)
+        named_paths = item.get("owned_paths") or (item.get("missing_file_names") if partition else None)
+        if isinstance(named_paths, list) and named_paths and all(isinstance(name, str) for name in named_paths):
+            path_owned_gaps.update(name.removeprefix("./") for name in named_paths)
         elif partition:
             scoped_graph_gaps.setdefault(partition, []).append(str(item["reason"]))
         else:
             unscoped_graph_gaps.append(str(item["reason"]))
+
+    def owns(path: str) -> bool:
+        path = path.removeprefix("./")
+        return path in path_owned_gaps or any(gap.endswith("/") and path.startswith(gap) for gap in path_owned_gaps)
+
     # A declared exclusion is a deliberate scope choice, not a failure to read the graph. It stays
     # in coverage, and whether a particular answer needed the excluded semantics is carried by that
     # question's own unresolved call destinations, not assumed for every answer in the repository.
@@ -636,12 +649,8 @@ def _scan_repository_impl(
             # own partition, and a question whose language the scan cannot place is treated as reached: an
             # unplaceable question is not evidence that the gap missed it.
             language = question.identity.language
-            reached = (
-                bool(unscoped_graph_gaps)
-                or bool(scoped_graph_gaps.get(language))
-                or question.identity.path.removeprefix("./") in file_owned_gaps.get(language, set())
-            )
-            if reached or ((scoped_graph_gaps or file_owned_gaps) and not language):
+            reached = bool(unscoped_graph_gaps) or bool(scoped_graph_gaps.get(language)) or owns(question.identity.path)
+            if reached or (scoped_graph_gaps and not language):
                 outcomes[rid] = replace(outcomes[rid], status="unresolved", reason="graph_incomplete")
     scope = replace(scope, unresolved_boundaries=tuple(dict.fromkeys((*scope.unresolved_boundaries, *graph_gaps, *declared_gaps))))
     ordered_outcomes = tuple(outcomes[q.identity.question_id] for q in scope.selected)
@@ -677,6 +686,23 @@ def _scan_repository_impl(
 # Reading the graph failed or produced something incomplete. An answer drawn from it cannot be
 # trusted, so a completed outcome is demoted.
 #
+def _boundary_degradations(cpg: Any) -> list[dict[str, Any]]:
+    """One degradation per boundary, carrying what it is about where the partition build recorded it: the
+    skipped paths of a symlink boundary, one entry per language no frontend reads. See the ownership rule in
+    `scan_repository`."""
+    paths = getattr(cpg, "boundary_paths", {}) or {}
+    languages = getattr(cpg, "boundary_languages", {}) or {}
+    out: list[dict[str, Any]] = []
+    for reason in cpg.boundaries:
+        if paths.get(reason):
+            out.append({"stage": "model", "reason": reason, "owned_paths": list(paths[reason])})
+        elif languages.get(reason):
+            out.extend({"stage": "model", "reason": reason, "census_language": language} for language in languages[reason])
+        else:
+            out.append({"stage": "model", "reason": reason})
+    return out
+
+
 # The test for membership is whether the gap could make a reported answer WRONG, not whether it cost
 # coverage. An unparsed file may hold the sanitizer that would have cleared a flow this scan reports,
 # so `files_unparsed` belongs here and demoting is the conservative reading. A missing file the
diff --git a/tests/test_model_change_context.py b/tests/test_model_change_context.py
index 6e083b1..02ce365 100644
--- a/tests/test_model_change_context.py
+++ b/tests/test_model_change_context.py
@@ -3,7 +3,7 @@
 from dataclasses import replace
 
 import pytest
-from test_model_scope import Backend, region, vector
+from test_model_scope import Backend, _CensusGapBackend, region, vector
 
 from openultrasast.model.contracts import ChangeContext, ChangedSpan, LineCorrespondence
 from openultrasast.model.scan import ScanBudget, scan_repository
@@ -233,7 +233,7 @@ def test_an_unresolved_context_projection_still_demotes_the_question(tmp_path):
     assert result.question_outcomes[0].reason == "change_context_incomplete"
 
 
-def scan_with_layout(tmp_path, *, vendor=False, symlink=False, second_language=False):
+def scan_with_layout(tmp_path, *, vendor=False, symlink=False, second_language=False, unnamed_census=False):
     """Exercise the real partition boundaries rather than injecting a reason."""
     (tmp_path / "source.php").write_text("readable\n")
     if vendor:
@@ -247,7 +247,7 @@ def scan_with_layout(tmp_path, *, vendor=False, symlink=False, second_language=F
     return scan_repository(
         tmp_path,
         [region("source.php", "php")],
-        backend=Backend({"source.php": rows}),
+        backend=_CensusGapBackend(None, evidence={"source.php": rows}) if unnamed_census else Backend({"source.php": rows}),
         change_context=context(),
     )
 
@@ -259,17 +259,24 @@ def test_a_declared_vendor_exclusion_does_not_invalidate_a_first_party_answer(tm
     assert result.question_outcomes[0].status == "completed"
 
 
-def test_an_unresolved_symlink_still_demotes_the_answer(tmp_path):
+def test_a_skipped_symlink_is_owned_by_its_own_path(tmp_path):
+    """alerta's one symlink, `alerta/app.wsgi` -- not even source -- made all 261 questions unresolved. The link
+    is skipped, so the graph is incomplete about THAT path; an answer about a file it read is still an answer.
+    The boundary stays reported, and it names the path."""
     result = scan_with_layout(tmp_path, symlink=True)
     assert "symlink_context_unresolved" in result.scope.unresolved_boundaries
-    assert result.question_outcomes[0].status == "unresolved"
-    assert result.question_outcomes[0].reason == "graph_incomplete"
+    gap = [d for d in result.degradations if d.get("reason") == "symlink_context_unresolved"]
+    assert gap and gap[0].get("owned_paths") == ["linked.php"], result.degradations
+    assert result.question_outcomes[0].status == "completed"
 
 
 def test_a_declared_exclusion_beside_an_integrity_failure_still_demotes(tmp_path):
-    result = scan_with_layout(tmp_path, vendor=True, symlink=True)
-    assert {"vendor_semantics_unresolved", "symlink_context_unresolved"} <= set(result.scope.unresolved_boundaries)
+    """A vendor exclusion must not mask a real integrity failure: a census gap naming no file reaches its
+    whole partition, excluded dependencies or not."""
+    result = scan_with_layout(tmp_path, vendor=True, unnamed_census=True)
+    assert {"vendor_semantics_unresolved", "partition_file_census_unavailable"} <= set(result.scope.unresolved_boundaries)
     assert result.question_outcomes[0].status == "unresolved"
+    assert result.question_outcomes[0].reason == "graph_incomplete"
 
 
 class FamilyBackend(Backend):
diff --git a/tests/test_model_scope.py b/tests/test_model_scope.py
index 039c548..9acd9cc 100644
--- a/tests/test_model_scope.py
+++ b/tests/test_model_scope.py
@@ -192,11 +192,18 @@ def test_missing_graph_files_disable_safe_pruning_and_completion(tmp_path):
             cpg.unparsed = ("missing.py",)
             return cpg
 
-    result = scan_repository(source(tmp_path, "a.py"), [region("a.py")], backend=Partial({"a.py": vector(False)}), ranking_mode="evidence")
-    assert len(result.scope.selected) == 1
+    result = scan_repository(
+        source(tmp_path, "a.py", "missing.py"),
+        [region("a.py"), region("missing.py")],
+        backend=Partial({"a.py": vector(False), "missing.py": vector(False)}),
+        ranking_mode="evidence",
+    )
+    # Pruning stays off: the unparsed file may hold the very sink a vector did not see.
+    assert len(result.scope.selected) == 2
     assert result.scope.deferred == ()
-    assert result.question_outcomes[0].status == "unresolved"
-    assert result.family_coverage[0].completed == 0
+    # Completion is owned by the file: the unparsed one is unresolved, the one the graph read is answered.
+    status = {o.identity.path: o.status for o in result.question_outcomes}
+    assert status == {"a.py": "completed", "missing.py": "unresolved"}, status
 
 
 def test_cli_sample_uses_deferred_order_not_scanned_count(tmp_path):
@@ -433,3 +440,16 @@ def test_a_census_gap_that_names_no_file_still_reaches_its_partition(tmp_path):
     regions = [region("app.py", "python"), region("other.py", "python")]
     result = scan_repository(root, regions, backend=_CensusGapBackend(None, evidence=evidence), population_complete=True)
     assert all(o.status == "unresolved" for o in result.question_outcomes), [(o.status, o.reason) for o in result.question_outcomes]
+
+
+def test_a_language_no_frontend_reads_demotes_only_its_own_questions(tmp_path):
+    """wger's Python questions all went unresolved because the repository also holds files of a language no
+    frontend reads. That gap is about THAT language; it is reported, and it names the language."""
+    root = source(tmp_path, "app.py")
+    (tmp_path / "tools").mkdir()
+    (tmp_path / "tools" / "main.go").write_text("package main\n")
+    result = scan_repository(root, [region("app.py")], backend=Backend({"app.py": vector()}), population_complete=True)
+    gap = [d for d in result.degradations if d.get("reason") == "frontend_unsupported"]
+    assert gap and gap[0].get("census_language") == "go", result.degradations
+    assert "frontend_unsupported" in result.scope.unresolved_boundaries
+    assert result.question_outcomes[0].status == "completed", result.question_outcomes