fix(#682): callers stops counting trailing-comment mentions as call sites

src/mcp.zig

@@ -2578,11 +2578,12 @@ fn handleCallers(alloc: std.mem.Allocator, args: *const std.json.ObjectMap, out:
             }
         }
         if (is_def) continue;
-        // A whole-word match that only ever lands inside a string literal is a
-        // mention, not an invocation — a `("name", "file")` table row or a
-        // `test "…name…" {` declaration. Real calls in the same file (and even
-        // in the same test body) sit outside the quotes and survive.
-        if (!hasWholeWordMatchOutsideStrings(r.line_text, name)) continue;
+        // A whole-word match that only ever lands inside a string literal or a
+        // trailing comment is a mention, not an invocation — a `("name",
+        // "file")` table row, a `test "…name…" {` declaration, or
+        // `init(); // then name() …`. Real calls sit on the code prefix of the
+        // line, outside the quotes, and survive both cuts. (#682)
+        if (!hasWholeWordMatchOutsideStrings(lineCodePrefix(r.line_text, lang), name)) continue;
         kept.append(alloc, r_idx) catch {};
     }
 
@@ -2682,6 +2683,47 @@ fn hasWholeWordMatchOutsideStrings(line: []const u8, needle: []const u8) bool {
     return false;
 }
 
+/// The slice of `line` before its first line-comment marker outside string
+/// literals, per `language` — the part of the line that can actually contain a
+/// call. Lines with no marker, and languages without a line-comment syntax
+/// (OCaml's `(* *)` is block-only), come back whole. (#682)
+///
+/// Same line-local scanning discipline as `hasWholeWordMatchOutsideStrings`:
+/// quoted spans are skipped (so `"https://…"` never truncates), an unclosed
+/// quote is ordinary code. Mid-line block-comment openers are left alone — a
+/// false negative re-admits a mention; truncating at `/*` could drop the real
+/// call in `foo(); /* … */ bar()`.
+fn lineCodePrefix(line: []const u8, language: explore_mod.Language) []const u8 {
+    const markers: []const []const u8 = switch (language) {
+        .zig, .rust, .go_lang, .javascript, .typescript, .c, .cpp, .dart, .java, .kotlin, .mlir, .tablegen, .rescript, .svelte, .vue, .astro => &.{"//"},
+        .python, .ruby, .r, .shell => &.{"#"},
+        .hcl => &.{ "#", "//" },
+        .sql => &.{"--"},
+        .fortran => &.{"!"},
+        .llvm_ir => &.{";"},
+        else => return line,
+    };
+    var i: usize = 0;
+    while (i < line.len) {
+        if (line[i] == '"' or line[i] == '\'') {
+            if (stringLiteralEnd(line, i)) |end| {
+                i = end + 1;
+                continue;
+            }
+        }
+        for (markers) |m| {
+            if (std.mem.startsWith(u8, line[i..], m)) {
+                // Shell: `#` only opens a comment at the start of a word —
+                // `${#var}` and `$#` are live syntax, not comments.
+                if (language == .shell and i != 0 and line[i - 1] != ' ' and line[i - 1] != '\t') break;
+                return line[0..i];
+            }
+        }
+        i += 1;
+    }
+    return line;
+}
+
 /// Index of the quote closing the literal opened at `open`, or null when the
 /// literal never closes on this line.
 fn stringLiteralEnd(line: []const u8, open: usize) ?usize {

src/test_mcp.zig

@@ -3785,6 +3785,42 @@ test "issue: codedb_callers keeps real calls inside and outside test bodies" {
     try testing.expect(std.mem.indexOf(u8, out.items, "body.zig:1") == null);
 }
 
+test "issue-682: codedb_callers excludes a symbol mentioned only in a trailing comment" {
+    // `init(); // then renderX() draws the frame` — the mention lives in the
+    // trailing comment. The comment/blank filter passes the line (it starts
+    // with code) and the string filter sees no quotes, so the line is
+    // reported as a call site even though nothing on it invokes the symbol.
+    var arena = std.heap.ArenaAllocator.init(testing.allocator);
+    defer arena.deinit();
+    var out: std.ArrayList(u8) = .empty;
+    defer out.deinit(testing.allocator);
+
+    try renderCallersFixture(arena.allocator(), &.{
+        .{ "trail.zig", "pub fn callerA() void {\n    init(); // then renderX() draws the frame\n}\n" },
+        .{ "call.zig", "pub fn callerB() void {\n    renderX();\n}\n" },
+    }, "renderX", &out);
+
+    try testing.expect(std.mem.indexOf(u8, out.items, "1 call sites for 'renderX'") != null);
+    try testing.expect(std.mem.indexOf(u8, out.items, "trail.zig:2") == null);
+    try testing.expect(std.mem.indexOf(u8, out.items, "call.zig:2") != null);
+}
+
+test "issue-682: codedb_callers keeps a call after a string containing the comment marker" {
+    // `fetch("https://x", renderX);` — the `//` sits inside the string literal,
+    // so the comment cut must not swallow the real reference after it.
+    var arena = std.heap.ArenaAllocator.init(testing.allocator);
+    defer arena.deinit();
+    var out: std.ArrayList(u8) = .empty;
+    defer out.deinit(testing.allocator);
+
+    try renderCallersFixture(arena.allocator(), &.{
+        .{ "url.zig", "pub fn callerA() void {\n    fetch(\"https://x\", renderX);\n}\n" },
+    }, "renderX", &out);
+
+    try testing.expect(std.mem.indexOf(u8, out.items, "1 call sites for 'renderX'") != null);
+    try testing.expect(std.mem.indexOf(u8, out.items, "url.zig:2") != null);
+}
+
 test "issue: codedb_callers keeps a symbol used outside a string on a line that has strings" {
     // `foo("msg", renderX)` passes the function by reference next to a string
     // literal — the mention is real code and must survive the filter.