diff --git a/plugins/axiomcode/skills/axiomcode/scripts/axiomcode-impact b/plugins/axiomcode/skills/axiomcode/scripts/axiomcode-impact
index 6c7d459f9..9e35904ae 100755
--- a/plugins/axiomcode/skills/axiomcode/scripts/axiomcode-impact
+++ b/plugins/axiomcode/skills/axiomcode/scripts/axiomcode-impact
@@ -394,9 +394,8 @@ class Impact:
         mfl = re.match(r'^(.+?):(\d+)(?::\d+)?$', s)
         if mfl and ('/' in mfl.group(1) or '.' in mfl.group(1)) and kind in (None, 'field', 'type'):
             f, ln = self.g.repo_file(mfl.group(1))[0], int(mfl.group(2))
-            files = sorted({x['file'] for x in self.g.q("SELECT DISTINCT file FROM symbols WHERE file = ? OR file LIKE ?", f, f"%/{f}")
-                            if x['file'] == f or (x['file'] or '').endswith('/' + f)})
-            if f in files: files = [f]
+            files, scoped = self.g.line_files(f)                          # --in chooses among a partial path's files (#1666)
+            if scoped and len(files) == 1: s = f"{files[0]}:{ln}"
             d = self.g.decl_at_line(files[0], ln) if len(files) == 1 else None
             if d and d[0] == 'field' and kind in (None, 'field'):
                 row = self.fields.get(d[1]['rowid']) or d[1]
@@ -568,8 +567,10 @@ class Impact:
         # the one declaration a file:line could not target, and its bare name answered for every const so named
         fl = re.fullmatch(r'(.+\.\w+):(\d+)', s)
         if fl:
-            p, n = fl.group(1), int(fl.group(2))
-            return [f for f in self.fields.values() if f['line'] == n and (f['file'] == p or (f['file'] or '').endswith('/' + p))]
+            # a partial path names ONE file, as for a callable (#1599, #1666): matched against every file it ends, it took
+            # the field at that line in whichever of them had one, so `test.js:6` in 17 test.js answered for one of them
+            files, _ = self.g.line_files(self.g.repo_file(fl.group(1))[0]); n = int(fl.group(2))
+            return [f for f in self.fields.values() if f['line'] == n and f['file'] == files[0]] if len(files) == 1 else []
         parts = s.split('.'); name = parts[-1]; owner = '.'.join(parts[:-1])
         rows = [f for f in self.fields.values() if f['name'] == name and (not owner or (f['owner'] or '') == owner or (f['owner'] or '').endswith('.' + owner) or (f['qualified_name'] or '').endswith('.' + s))]
         if not rows and '.' in s:                                                     # the dotted spelling, only after the written one
diff --git a/plugins/axiomcode/skills/axiomcode/scripts/axiomcode-path b/plugins/axiomcode/skills/axiomcode/scripts/axiomcode-path
index 754c27d18..c57d48bed 100755
--- a/plugins/axiomcode/skills/axiomcode/scripts/axiomcode-path
+++ b/plugins/axiomcode/skills/axiomcode/scripts/axiomcode-path
@@ -324,6 +324,18 @@ class G:
         try:
             with open(os.path.join(self.repo, f), 'rb') as h: return len(h.read().splitlines())
         except OSError: return None
+
+    def line_files(self, f):
+        """-> (the indexed files a file:line's path `f` names, the --in note when the scope chose among them). The file
+        written in full, else every file `f` is a suffix of. --IN CHOOSES AMONG THEM (#1666): it was applied only after
+        the file was settled, so `index.js:2 --in packages/a` was refused with every index.js listed. Under the scope
+        one file is the answer; two or more are the refusal's list; none leaves the list whole, and says so."""
+        files = sorted({x['file'] for x in self.q("SELECT DISTINCT file FROM symbols WHERE file = ? OR file LIKE ?", f, f"%/{f}")
+                        if x['file'] == f or (x['file'] or '').endswith('/' + f)})
+        if f in files: return [f], ''
+        if len(files) < 2 or not self.IN: return files, ''
+        kept = [x for x in files if self.under_in(x)]
+        return (kept, f" under *{self.IN}*") if kept else (files, f", none of them under *{self.IN}*")
     def _resolve(self, sel, fragment=False):
         s = sel.strip().strip('`"\'')
         # file:line, or file:line:col as a stack trace prints it — the column never changes which callable spans the line
@@ -334,17 +346,16 @@ class G:
             # lib/ took the smallest span across BOTH files, so the answer was for whichever function at that line was
             # shorter, labelled with what was typed. The path is settled first: the file written in full, else the one
             # file it is a suffix of; two or more are listed, each with what spans the line there.
-            files = sorted({x['file'] for x in self.q("SELECT DISTINCT file FROM symbols WHERE file = ? OR file LIKE ?", f, f"%/{f}")
-                            if x['file'] == f or (x['file'] or '').endswith('/' + f)})
-            if f in files: files = [f]
+            files, scoped = self.line_files(f)
             if len(files) > 1:
                 rows = []
                 for fx in files[:12]:
                     at = self.q("SELECT id FROM symbols WHERE file = ? AND line <= ? AND end_line >= ? AND method_id IS NOT NULL AND kind <> 'module' ORDER BY end_line - line LIMIT 1", fx, ln, ln)
                     rows.append(f"  {fx}:{ln}   " + (self.disp(at[0]['id']) if at else '(top-level code)'))
                 if len(files) > 12: rows.append(f"  … +{len(files) - 12} more")
-                die(f"'{m.group(1)}' matches {len(files)} indexed files — give enough of the path to name one:\n" + '\n'.join(rows))
+                die(f"'{m.group(1)}' matches {len(files)} indexed files{scoped} — give enough of the path to name one:\n" + '\n'.join(rows))
             if files: f = files[0]
+            if scoped: s = f"{f}:{ln}"                                   # the scope chose the file: the label names it
             # A LINE OUTSIDE THE FILE IS REFUSED (#1601). Line 0, or a line past the end — a number copied before the file
             # was edited, or from an old stack trace — spans no callable, so it fell through to the module node and was
             # answered as the file's top-level code, as if that line existed. The file on disk is what the reader sees.
diff --git a/tests/cases/javascript/fileline-partial-path-in-scope/case.json b/tests/cases/javascript/fileline-partial-path-in-scope/case.json
new file mode 100644
index 000000000..e0085d4de
--- /dev/null
+++ b/tests/cases/javascript/fileline-partial-path-in-scope/case.json
@@ -0,0 +1,48 @@
+{"lang": "javascript",
+ "checks": [
+  {"why": "a basename matching five indexed files, one of them under --in, answers for that one and names it (#1666)",
+   "run": ["impact", "index.js:2", "--in", "packages/a"],
+   "want": ["change: runA (at packages/a/src/index.js:2)", "startA"],
+   "avoid": ["matches 5 indexed files", "startB", "runB"]},
+  {"why": "the same through path, from everything into the one file under --in",
+   "run": ["path", "*", "index.js:2", "--in", "packages/b"],
+   "want": ["startB"],
+   "avoid": ["matches 5 indexed files", "startA"]},
+  {"why": "a dir/file suffix is narrowed the same way",
+   "run": ["impact", "src/index.js:2", "--in", "packages/b"],
+   "want": ["change: runB (at packages/b/src/index.js:2)", "startB"],
+   "avoid": ["matches 2 indexed files", "startA"]},
+  {"why": "control: a scope that still leaves two files is refused, listing only those two",
+   "run": ["impact", "index.js:2", "--in", "packages/c"],
+   "expect_error": true,
+   "want": ["matches 2 indexed files under *packages/c*", "packages/c/index.js:2", "packages/c/lib/index.js:2"],
+   "avoid": ["packages/a/src/index.js", "change: load"]},
+  {"why": "control: the same through path",
+   "run": ["path", "*", "index.js:2", "--in", "packages/c"],
+   "expect_error": true,
+   "want": ["matches 2 indexed files under *packages/c*"],
+   "avoid": ["packages/d/index.js"]},
+  {"why": "control: a scope holding none of the files is refused with every file listed",
+   "run": ["impact", "index.js:2", "--in", "shared"],
+   "expect_error": true,
+   "want": ["matches 5 indexed files", "none of them under *shared*", "packages/a/src/index.js:2", "packages/d/index.js:2"]},
+  {"why": "control: without --in the basename is refused as before (#1599)",
+   "run": ["impact", "index.js:2"],
+   "expect_error": true,
+   "want": ["matches 5 indexed files", "packages/a/src/index.js:2", "packages/c/lib/index.js:2"]},
+  {"why": "control: the full path with --in answers for it, labelled as typed",
+   "run": ["impact", "packages/a/src/index.js:2", "--in", "packages/a"],
+   "want": ["change: runA (at packages/a/src/index.js:2)", "startA"],
+   "avoid": ["startB"]},
+  {"why": "a const on the line of a partial path matching two files is refused, not answered for one of them",
+   "run": ["impact", "config.js:1"],
+   "expect_error": true,
+   "want": ["matches 2 indexed files", "packages/a/src/config.js:1", "packages/b/src/config.js:1"],
+   "avoid": ["change: variable tokenA", "change: const tokenA"]},
+  {"why": "the same const line with --in answers for the one file under the scope",
+   "run": ["impact", "config.js:1", "--in", "packages/b"],
+   "want": ["tokenB"],
+   "avoid": ["tokenA", "matches 2 indexed files"]},
+  {"why": "control: a partial path matching one file is labelled as typed, with or without --in",
+   "run": ["impact", "d/index.js:2", "--in", "packages"],
+   "want": ["change: main (at d/index.js:2)"]}]}
diff --git a/tests/cases/javascript/fileline-partial-path-in-scope/packages/a/src/app.js b/tests/cases/javascript/fileline-partial-path-in-scope/packages/a/src/app.js
new file mode 100644
index 000000000..df44eb3b9
--- /dev/null
+++ b/tests/cases/javascript/fileline-partial-path-in-scope/packages/a/src/app.js
@@ -0,0 +1,7 @@
+const { runA } = require('./index');
+
+function startA() {
+  return runA(1);
+}
+
+module.exports = { startA };
diff --git a/tests/cases/javascript/fileline-partial-path-in-scope/packages/a/src/config.js b/tests/cases/javascript/fileline-partial-path-in-scope/packages/a/src/config.js
new file mode 100644
index 000000000..77db3fb2b
--- /dev/null
+++ b/tests/cases/javascript/fileline-partial-path-in-scope/packages/a/src/config.js
@@ -0,0 +1,2 @@
+const tokenA = 'a';
+module.exports = { tokenA };
diff --git a/tests/cases/javascript/fileline-partial-path-in-scope/packages/a/src/index.js b/tests/cases/javascript/fileline-partial-path-in-scope/packages/a/src/index.js
new file mode 100644
index 000000000..535663afa
--- /dev/null
+++ b/tests/cases/javascript/fileline-partial-path-in-scope/packages/a/src/index.js
@@ -0,0 +1,4 @@
+function runA(x) {
+  return String(x);
+}
+module.exports = { runA };
diff --git a/tests/cases/javascript/fileline-partial-path-in-scope/packages/b/src/app.js b/tests/cases/javascript/fileline-partial-path-in-scope/packages/b/src/app.js
new file mode 100644
index 000000000..e3b3f5f9f
--- /dev/null
+++ b/tests/cases/javascript/fileline-partial-path-in-scope/packages/b/src/app.js
@@ -0,0 +1,7 @@
+const { runB } = require('./index');
+
+function startB() {
+  return runB('1');
+}
+
+module.exports = { startB };
diff --git a/tests/cases/javascript/fileline-partial-path-in-scope/packages/b/src/config.js b/tests/cases/javascript/fileline-partial-path-in-scope/packages/b/src/config.js
new file mode 100644
index 000000000..d0abade26
--- /dev/null
+++ b/tests/cases/javascript/fileline-partial-path-in-scope/packages/b/src/config.js
@@ -0,0 +1,2 @@
+const tokenB = 'b';
+module.exports = { tokenB };
diff --git a/tests/cases/javascript/fileline-partial-path-in-scope/packages/b/src/index.js b/tests/cases/javascript/fileline-partial-path-in-scope/packages/b/src/index.js
new file mode 100644
index 000000000..04b42876d
--- /dev/null
+++ b/tests/cases/javascript/fileline-partial-path-in-scope/packages/b/src/index.js
@@ -0,0 +1,4 @@
+function runB(x) {
+  return Number(x);
+}
+module.exports = { runB };
diff --git a/tests/cases/javascript/fileline-partial-path-in-scope/packages/c/index.js b/tests/cases/javascript/fileline-partial-path-in-scope/packages/c/index.js
new file mode 100644
index 000000000..c6c4483ec
--- /dev/null
+++ b/tests/cases/javascript/fileline-partial-path-in-scope/packages/c/index.js
@@ -0,0 +1,4 @@
+function load() {
+  return 1;
+}
+module.exports = { load };
diff --git a/tests/cases/javascript/fileline-partial-path-in-scope/packages/c/lib/index.js b/tests/cases/javascript/fileline-partial-path-in-scope/packages/c/lib/index.js
new file mode 100644
index 000000000..a6bf9045a
--- /dev/null
+++ b/tests/cases/javascript/fileline-partial-path-in-scope/packages/c/lib/index.js
@@ -0,0 +1,4 @@
+function loadLib() {
+  return 2;
+}
+module.exports = { loadLib };
diff --git a/tests/cases/javascript/fileline-partial-path-in-scope/packages/d/index.js b/tests/cases/javascript/fileline-partial-path-in-scope/packages/d/index.js
new file mode 100644
index 000000000..3addcf4e5
--- /dev/null
+++ b/tests/cases/javascript/fileline-partial-path-in-scope/packages/d/index.js
@@ -0,0 +1,4 @@
+function main() {
+  return 3;
+}
+module.exports = { main };
diff --git a/tests/cases/javascript/fileline-partial-path-in-scope/shared/util.js b/tests/cases/javascript/fileline-partial-path-in-scope/shared/util.js
new file mode 100644
index 000000000..eaa593faa
--- /dev/null
+++ b/tests/cases/javascript/fileline-partial-path-in-scope/shared/util.js
@@ -0,0 +1,4 @@
+function helper() {
+  return 4;
+}
+module.exports = { helper };