diff --git a/desloppify/languages/_framework/treesitter/imports/graph.py b/desloppify/languages/_framework/treesitter/imports/graph.py
index 361586356..831f310ec 100644
--- a/desloppify/languages/_framework/treesitter/imports/graph.py
+++ b/desloppify/languages/_framework/treesitter/imports/graph.py
@@ -75,6 +75,16 @@ def ts_build_dep_graph(
             if resolved is None:
                 continue
 
+            # Check if the resolver returned a relative path that is already
+            # in the file set (relative to the project root) before converting
+            # to absolute. This handles cases where resolve_import returns a
+            # project-root-relative path rather than a scan-root-relative one.
+            if not os.path.isabs(resolved) and resolved in file_set:
+                graph[filepath]["imports"].add(resolved)
+                if resolved in graph:
+                    graph[resolved]["importers"].add(filepath)
+                continue
+
             # Normalize to absolute path.
             if not os.path.isabs(resolved):
                 resolved = os.path.normpath(os.path.join(scan_path, resolved))
diff --git a/desloppify/languages/javascript/__init__.py b/desloppify/languages/javascript/__init__.py
index dc5b83f2d..86984f2c0 100644
--- a/desloppify/languages/javascript/__init__.py
+++ b/desloppify/languages/javascript/__init__.py
@@ -9,6 +9,7 @@
 )
 from desloppify.languages._framework.treesitter import JS_SPEC
 from desloppify.languages.javascript._zones import JS_ZONE_RULES
+from desloppify.languages.javascript import test_coverage as js_test_coverage_hooks
 
 
 cfg = generic_lang(
@@ -31,6 +32,7 @@
     treesitter_spec=JS_SPEC,
     zone_rules=JS_ZONE_RULES,
     frameworks=True,
+    test_coverage_module=js_test_coverage_hooks,
 )
 
 # Append Open Paws advocacy phases to the generic config.
diff --git a/desloppify/languages/javascript/test_coverage.py b/desloppify/languages/javascript/test_coverage.py
new file mode 100644
index 000000000..408ec6b3c
--- /dev/null
+++ b/desloppify/languages/javascript/test_coverage.py
@@ -0,0 +1,120 @@
+"""JavaScript-specific test coverage heuristics.
+
+Supports Jest/Vitest/Mocha test naming conventions (.test.js, .spec.js) and
+Node.js built-in assert module patterns.
+"""
+
+from __future__ import annotations
+
+import os
+import re
+
+_IMPORT_RE = re.compile(
+    r"""(?:\bfrom\s+|\bimport\s*\(\s*|\bimport\s+)(?:type\s+)?['"]([^'"]+)['"]|"""
+    r"""(?:\brequire\s*\(\s*)['"]([^'"]+)['"]""",
+    re.MULTILINE,
+)
+
+# Patterns for detecting assertion calls in JS test files
+ASSERT_PATTERNS = [
+    re.compile(p)
+    for p in [
+        r"expect\(",
+        r"assert\.",
+        r"\.should\.",
+        r"\b(?:getBy|findBy|getAllBy|findAllBy)\w+\(",
+        r"\.toBeInTheDocument\(",
+        r"\.toBeVisible\(",
+        r"\.toHaveTextContent\(",
+        r"\.toHaveAttribute\(",
+    ]
+]
+
+MOCK_PATTERNS = [
+    re.compile(p)
+    for p in [
+        r"jest\.mock\(",
+        r"jest\.spyOn\(",
+        r"vi\.mock\(",
+        r"vi\.spyOn\(",
+        r"sinon\.",
+    ]
+]
+
+SNAPSHOT_PATTERNS: list[re.Pattern[str]] = []
+
+# Detects test('name', ...) or it('name', ...) call patterns
+TEST_FUNCTION_RE = re.compile(r"""(?:it|test)\s*\(\s*['"]""")
+
+
+def parse_test_import_specs(content: str) -> set[str]:
+    """Extract import/require specs from a JavaScript test file."""
+    return {
+        spec
+        for m in _IMPORT_RE.finditer(content)
+        if (spec := m.group(1) or m.group(2))
+    }
+
+
+def map_test_to_source(test_path: str, production_set: set[str]) -> str | None:
+    """Map a JavaScript test file to a production file by naming convention."""
+    basename = os.path.basename(test_path)
+    dirname = os.path.dirname(test_path)
+    parent = os.path.dirname(dirname)
+
+    candidates: list[str] = []
+
+    for pattern in (".test.", ".spec."):
+        if pattern in basename:
+            src = basename.replace(pattern, ".")
+            candidates.append(os.path.join(dirname, src))
+            if parent:
+                candidates.append(os.path.join(parent, src))
+
+    dir_basename = os.path.basename(dirname)
+    if dir_basename == "__tests__" and parent:
+        candidates.append(os.path.join(parent, basename))
+
+    # Exact path match takes priority.
+    for c in candidates:
+        if c in production_set:
+            return c
+
+    # Deterministic basename fallback: build a sorted basename → path mapping,
+    # then return the first match across sorted candidates to avoid non-determinism
+    # when multiple production files share the same basename.
+    prod_base_map: dict[str, list[str]] = {}
+    for prod in sorted(production_set):
+        prod_base_map.setdefault(os.path.basename(prod), []).append(prod)
+
+    for c in sorted(candidates):
+        matches = prod_base_map.get(os.path.basename(c), [])
+        if matches:
+            return matches[0]
+
+    return None
+
+
+def strip_test_markers(basename: str) -> str | None:
+    """Strip JavaScript test naming markers to derive a source basename."""
+    for marker in (".test.", ".spec."):
+        if marker in basename:
+            return basename.replace(marker, ".")
+    return None
+
+
+def resolve_import_spec(
+    spec: str, test_path: str, production_files: set[str]
+) -> str | None:
+    """Resolve a JS import spec to a production file path."""
+    if not spec.startswith("."):
+        return None
+
+    base = os.path.dirname(test_path)
+    candidate = os.path.normpath(os.path.join(base, spec))
+    for ext in ("", ".js", ".jsx", ".mjs", ".cjs", "/index.js", "/index.jsx"):
+        path = candidate + ext
+        if path in production_files:
+            return path
+
+    return None
diff --git a/desloppify/tests/lang/common/test_treesitter_imports_direct.py b/desloppify/tests/lang/common/test_treesitter_imports_direct.py
index 2a75eb119..85edd85b0 100644
--- a/desloppify/tests/lang/common/test_treesitter_imports_direct.py
+++ b/desloppify/tests/lang/common/test_treesitter_imports_direct.py
@@ -317,3 +317,60 @@ def test_script_import_cache_reset_invalidates_php_lookup_state(tmp_path: Path)
     scripts_mod.reset_script_import_caches(str(tmp_path))
 
     assert scripts_mod.resolve_php_import("User", "", str(tmp_path)) == str(second_file)
+
+
+def test_graph_records_project_root_relative_import_without_scan_path_join(
+    monkeypatch, tmp_path: Path
+) -> None:
+    """Characterization test: resolve_import returning a project-root-relative path
+    must be added directly to the graph rather than being joined with scan_path.
+
+    Before the fix, ts_build_dep_graph would join scan_path (e.g. ``/project/_ui``)
+    with the relative path (e.g. ``_ui/server.js``) producing
+    ``/project/_ui/_ui/server.js``, which is never in file_set, so the import
+    edge was silently dropped.  After the fix, the relative path is detected in
+    file_set first and added without any join.
+    """
+    # Simulate a sub-directory scan: project root is tmp_path, scan_path is
+    # tmp_path/_ui, so file_set uses project-root-relative strings.
+    scan_dir = tmp_path / "_ui"
+    scan_dir.mkdir()
+    source_file = scan_dir / "server.test.js"
+    dep_file = scan_dir / "server.js"
+    source_file.write_text("const s = require('./server');\n", encoding="utf-8")
+    dep_file.write_text("module.exports = {};\n", encoding="utf-8")
+
+    # file_set uses project-root-relative paths (as produced by the real scanner).
+    rel_source = "_ui/server.test.js"
+    rel_dep = "_ui/server.js"
+    file_list = [rel_source, rel_dep]
+
+    monkeypatch.setattr(graph_mod, "_get_parser", lambda _grammar: ("parser", "language"))
+    monkeypatch.setattr(graph_mod, "_make_query", lambda _language, source: source)
+    monkeypatch.setattr(
+        graph_mod,
+        "get_or_parse_tree",
+        lambda filepath, *_a, **_k: (b"", SimpleNamespace(root_node=filepath)),
+    )
+    matches = {
+        rel_source: [(0, {"path": FakeNode("string", text="'./server'")})],
+        rel_dep: [],
+    }
+    monkeypatch.setattr(graph_mod, "_run_query", lambda _query, root: matches[root])
+    monkeypatch.setattr(graph_mod, "_unwrap_node", lambda node: node)
+
+    # resolve_import returns a project-root-relative path (not absolute).
+    # Before the fix this would be joined with scan_path → wrong absolute path.
+    spec = SimpleNamespace(
+        grammar="javascript",
+        import_query="imports",
+        resolve_import=lambda text, filepath, scan_path: rel_dep,
+    )
+
+    graph = graph_mod.ts_build_dep_graph(scan_dir, spec, file_list)
+
+    # The import edge must be recorded using the project-root-relative key.
+    assert rel_dep in graph[rel_source]["imports"], (
+        "import edge was not recorded — path was likely incorrectly joined with scan_path"
+    )
+    assert rel_source in graph[rel_dep]["importers"]
diff --git a/desloppify/tests/lang/javascript/__init__.py b/desloppify/tests/lang/javascript/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/desloppify/tests/lang/javascript/test_javascript_test_coverage.py b/desloppify/tests/lang/javascript/test_javascript_test_coverage.py
new file mode 100644
index 000000000..0ff32a927
--- /dev/null
+++ b/desloppify/tests/lang/javascript/test_javascript_test_coverage.py
@@ -0,0 +1,79 @@
+"""Tests for JavaScript-specific test coverage detection hooks."""
+
+from __future__ import annotations
+
+import os
+
+from desloppify.languages.javascript import test_coverage as js_cov
+
+
+def test_parse_test_import_specs_handles_esm_and_cjs() -> None:
+    content = (
+        "import { foo } from './foo.js';\n"
+        "import './side-effect.js';\n"
+        "const bar = require('./bar');\n"
+        "import('./lazy.js');\n"
+    )
+    specs = js_cov.parse_test_import_specs(content)
+    assert isinstance(specs, set)
+    assert "./foo.js" in specs
+    assert "./side-effect.js" in specs
+    assert "./bar" in specs
+    assert "./lazy.js" in specs
+
+
+def test_parse_test_import_specs_deduplicates() -> None:
+    content = "require('./util');\nrequire('./util');\n"
+    specs = js_cov.parse_test_import_specs(content)
+    assert specs == {"./util"}
+
+
+def test_parse_test_import_specs_returns_empty_set_for_no_imports() -> None:
+    assert js_cov.parse_test_import_specs("const x = 1;") == set()
+
+
+def test_strip_test_markers_removes_test_suffix() -> None:
+    assert js_cov.strip_test_markers("server.test.js") == "server.js"
+    assert js_cov.strip_test_markers("util.spec.js") == "util.js"
+    assert js_cov.strip_test_markers("app.js") is None
+
+
+def test_map_test_to_source_finds_sibling_file() -> None:
+    production_set = {"_ui/server.js", "_ui/github.js", "_ui/public/app.js"}
+    result = js_cov.map_test_to_source("_ui/server.test.js", production_set)
+    assert result == "_ui/server.js"
+
+
+def test_map_test_to_source_returns_none_when_no_match() -> None:
+    production_set = {"_ui/server.js"}
+    result = js_cov.map_test_to_source("_ui/missing.test.js", production_set)
+    assert result is None
+
+
+def test_resolve_import_spec_resolves_relative_js_path() -> None:
+    production = {"_ui/server.js", "_ui/github.js"}
+    result = js_cov.resolve_import_spec("./server.js", "_ui/server.test.js", production)
+    assert result == "_ui/server.js"
+
+
+def test_resolve_import_spec_adds_js_extension() -> None:
+    production = {"_ui/server.js"}
+    result = js_cov.resolve_import_spec("./server", "_ui/server.test.js", production)
+    assert result == "_ui/server.js"
+
+
+def test_resolve_import_spec_skips_node_modules() -> None:
+    production = {"_ui/server.js"}
+    result = js_cov.resolve_import_spec("express", "_ui/server.test.js", production)
+    assert result is None
+
+
+def test_map_test_to_source_is_deterministic_on_basename_collision() -> None:
+    # Two production files with the same basename in different directories.
+    production = {"a/util.js", "b/util.js"}
+    result1 = js_cov.map_test_to_source("test/util.test.js", production)
+    # Call twice — result must be stable (no randomness from set iteration).
+    result2 = js_cov.map_test_to_source("test/util.test.js", production)
+    assert result1 == result2
+    # Sorted basename fallback must pick the lexicographically first path.
+    assert result1 == "a/util.js"