fix(mcp): reject stale AST coordinates after source changes

src/mcp/mcp.c

@@ -6306,7 +6306,18 @@ static const char *coverage_path_freshness(cbm_store_t *store, const char *proje
     if (rc != CBM_STORE_OK) {
         return "unavailable";
     }
-    bool matches = hash.mtime_ns == coverage_stat_mtime_ns(&st) && hash.size == st.st_size;
+    bool matches;
+#ifdef _WIN32
+    cbm_path_info_t path_info = {0};
+    matches = cbm_path_info_utf8(abs_path, &path_info) == CBM_PATH_INFO_OK &&
+              hash.mtime_ns == path_info.mtime_ns && hash.size == path_info.size;
+    /* Imported artifacts may have been restamped from Windows stat() values. */
+    if (!matches && hash.mtime_ns >= 0 && hash.mtime_ns % CBM_NSEC_PER_SEC == 0) {
+        matches = hash.mtime_ns == coverage_stat_mtime_ns(&st) && hash.size == st.st_size;
+    }
+#else
+    matches = hash.mtime_ns == coverage_stat_mtime_ns(&st) && hash.size == st.st_size;
+#endif
     cbm_store_clear_file_hash(&hash);
     return matches ? "metadata_match" : "metadata_changed";
 }
@@ -11668,6 +11679,17 @@ static char *build_snippet_response(cbm_mcp_server_t *srv, cbm_node_t *node,
                                     cbm_node_t *alternatives, int alt_count, const char *args) {
     char *root_path = get_project_root(srv, node->project);
 
+    bool outside = false;
+    const char *freshness =
+        coverage_path_freshness(srv->store, node->project, root_path, node->file_path, &outside);
+    if (strcmp(freshness, "metadata_match") != 0 && strcmp(freshness, "not_tracked") != 0) {
+        free(root_path);
+        return cbm_mcp_text_result(
+            "source changed since indexing; re-index the project before requesting this "
+            "snippet",
+            true);
+    }
+
     int original_start = node->start_line > 0 ? node->start_line : SKIP_ONE;
     /* A one-line symbol legitimately has end == start. Treat only missing or
      * inverted end metadata as unknown; expanding a valid one-line node by 50
@@ -13828,8 +13850,14 @@ static bool scan_and_classify_grep_matches(
                 break;
             }
             if (store) {
-                (void)cbm_store_find_nodes_by_file(store, project, file, &file_nodes,
-                                                   &file_node_count);
+                bool outside = false;
+                const char *freshness =
+                    coverage_path_freshness(store, project, root_path, file, &outside);
+                if (strcmp(freshness, "metadata_match") == 0 ||
+                    strcmp(freshness, "not_tracked") == 0) {
+                    (void)cbm_store_find_nodes_by_file(store, project, file, &file_nodes,
+                                                       &file_node_count);
+                }
             }
         }
 

tests/test_mcp.c

@@ -2866,6 +2866,104 @@ TEST(tool_get_architecture_cycles_detects_scc) {
     PASS();
 }
 
+/* A source edit after indexing invalidates stored line coordinates. The read
+ * tools must not present those coordinates as current source truth. */
+TEST(tool_get_code_snippet_rejects_changed_source_coordinates_issue1750) {
+    char tmp[256];
+    cbm_mcp_server_t *srv = setup_snippet_server(tmp, sizeof(tmp));
+    ASSERT_NOT_NULL(srv);
+    cbm_store_t *store = cbm_mcp_server_store(srv);
+    ASSERT_NOT_NULL(store);
+
+    char source_path[512];
+    snprintf(source_path, sizeof(source_path), "%s/project/main.go", tmp);
+    struct stat source_stat;
+    ASSERT_EQ(stat(source_path, &source_stat), 0);
+#ifdef __APPLE__
+    int64_t source_mtime_ns =
+        ((int64_t)source_stat.st_mtimespec.tv_sec * (int64_t)CBM_NSEC_PER_SEC) +
+        (int64_t)source_stat.st_mtimespec.tv_nsec;
+#elif defined(_WIN32)
+    int64_t source_mtime_ns = (int64_t)source_stat.st_mtime * (int64_t)CBM_NSEC_PER_SEC;
+#else
+    int64_t source_mtime_ns = ((int64_t)source_stat.st_mtim.tv_sec * (int64_t)CBM_NSEC_PER_SEC) +
+                              (int64_t)source_stat.st_mtim.tv_nsec;
+#endif
+    ASSERT_EQ(cbm_store_upsert_file_hash(store, "test-project", "main.go", "fixture",
+                                         source_mtime_ns, source_stat.st_size),
+              CBM_STORE_OK);
+
+    FILE *fp = fopen(source_path, "w");
+    ASSERT_NOT_NULL(fp);
+    fputs("// inserted\n// inserted\npackage main\n\n"
+          "func HandleRequest() error {\n\treturn nil\n}\n\n"
+          "func ProcessOrder(id int) {\n\t// process\n}\n\n"
+          "func Run() {\n\t// server\n}\n",
+          fp);
+    fclose(fp);
+
+    char *response = cbm_mcp_handle_tool(
+        srv, "get_code_snippet",
+        "{\"project\":\"test-project\",\"qualified_name\":\""
+        "test-project.cmd.server.main.ProcessOrder\",\"format\":\"json\"}");
+    ASSERT_NOT_NULL(response);
+    ASSERT_NOT_NULL(strstr(response, "isError"));
+    ASSERT_NOT_NULL(strstr(response, "changed since indexing"));
+    ASSERT_NULL(strstr(response, "// process"));
+    free(response);
+    cbm_mcp_server_free(srv);
+    cleanup_snippet_dir(tmp);
+    PASS();
+}
+
+TEST(tool_search_code_does_not_map_changed_source_to_stale_nodes_issue1750) {
+    char tmp[256];
+    cbm_mcp_server_t *srv = setup_snippet_server(tmp, sizeof(tmp));
+    ASSERT_NOT_NULL(srv);
+    cbm_store_t *store = cbm_mcp_server_store(srv);
+    ASSERT_NOT_NULL(store);
+
+    char source_path[512];
+    snprintf(source_path, sizeof(source_path), "%s/project/main.go", tmp);
+    struct stat source_stat;
+    ASSERT_EQ(stat(source_path, &source_stat), 0);
+#ifdef __APPLE__
+    int64_t source_mtime_ns =
+        ((int64_t)source_stat.st_mtimespec.tv_sec * (int64_t)CBM_NSEC_PER_SEC) +
+        (int64_t)source_stat.st_mtimespec.tv_nsec;
+#elif defined(_WIN32)
+    int64_t source_mtime_ns = (int64_t)source_stat.st_mtime * (int64_t)CBM_NSEC_PER_SEC;
+#else
+    int64_t source_mtime_ns = ((int64_t)source_stat.st_mtim.tv_sec * (int64_t)CBM_NSEC_PER_SEC) +
+                              (int64_t)source_stat.st_mtim.tv_nsec;
+#endif
+    ASSERT_EQ(cbm_store_upsert_file_hash(store, "test-project", "main.go", "fixture",
+                                         source_mtime_ns, source_stat.st_size),
+              CBM_STORE_OK);
+
+    FILE *fp = fopen(source_path, "w");
+    ASSERT_NOT_NULL(fp);
+    fputs("// inserted\n// inserted\npackage main\n\n"
+          "func HandleRequest() error {\n\treturn nil\n}\n\n"
+          "func ProcessOrder(id int) {\n\t// process\n}\n\n"
+          "func Run() {\n\t// server\n}\n",
+          fp);
+    fclose(fp);
+
+    char *response = cbm_mcp_handle_tool(
+        srv, "search_code",
+        "{\"project\":\"test-project\",\"pattern\":\"process\","
+        "\"mode\":\"full\",\"format\":\"json\"}");
+    ASSERT_NOT_NULL(response);
+    ASSERT_NOT_NULL(strstr(response, "raw_matches"));
+    ASSERT_NOT_NULL(strstr(response, "// process"));
+    ASSERT_NULL(strstr(response, "test-project.cmd.server.main.ProcessOrder"));
+    free(response);
+    cbm_mcp_server_free(srv);
+    cleanup_snippet_dir(tmp);
+    PASS();
+}
+
 /* Context-bomb guard: get_code_snippet on a whole-file node (a Module/File
  * span) used to read the ENTIRE file into one response — a field-eval agent
  * that fell back to a Module snippet pulled ~400KB in a single call. The read
@@ -20087,6 +20185,7 @@ SUITE(mcp) {
     RUN_TEST(tool_trace_totals_respect_test_filter_tests_root_subtree_issue1294);
     RUN_TEST(tool_get_architecture_cycles_detects_scc);
     RUN_TEST(tool_get_code_snippet_clips_whole_file_node);
+    RUN_TEST(tool_get_code_snippet_rejects_changed_source_coordinates_issue1750);
     RUN_TEST(tool_get_code_snippet_omits_over_budget_whole_line);
     RUN_TEST(tool_get_code_snippet_pages_outline_rows_to_exact_budget);
     RUN_TEST(tool_search_graph_includes_node_properties);
@@ -20167,6 +20266,7 @@ SUITE(mcp) {
     RUN_TEST(tool_search_code_limit_declares_a_minimum_issue1511);
     RUN_TEST(tool_search_code_declares_independent_result_and_raw_content_paging);
     RUN_TEST(tool_search_code_no_project);
+    RUN_TEST(tool_search_code_does_not_map_changed_source_to_stale_nodes_issue1750);
     RUN_TEST(search_code_multi_word);
     RUN_TEST(search_code_full_preserves_utf8_source);
     RUN_TEST(search_code_raw_match_preserves_utf8_content);