diff --git a/implementations/Crafter.Build-Lint.cpp b/implementations/Crafter.Build-Lint.cpp
index 357fb33..39e4be0 100644
--- a/implementations/Crafter.Build-Lint.cpp
+++ b/implementations/Crafter.Build-Lint.cpp
@@ -1149,6 +1149,10 @@ format` applies it to disk, and `crafter-build lint` reports where it would.
     // command per configuration — GetCompileCommand walks the dependency tree.
     const bool anyRuleNeedsAst = std::ranges::any_of(rules, [](const LintRule* r) { return r->needsAst; });
     std::unordered_map<const Configuration*, std::string> commands;
+    // Why a configuration of the build graph has no command: its files
+    // cannot be parsed, which fails the run. Cleared to nothing, the command
+    // read as "not a translation unit" and every semantic rule passed them.
+    std::unordered_map<const Configuration*, std::string> commandErrors;
     if (anyRuleNeedsAst && !opts.noAst) {
         for (Configuration* c : localConfigs) {
             auto ensure = [&](const Configuration& cfg) {
@@ -1166,10 +1170,14 @@ format` applies it to disk, and `crafter-build lint` reports where it would.
                         Progress::Task task(std::format("Building std PCM ({}-{})", cfg.target, cfg.march));
                         fs::create_directories(assembled.stdPcmDir);
                         std::string error = BuildStdPcm(cfg, assembled.stdPcmDir/"std.pcm");
-                        if (!error.empty()) command.clear();
+                        if (!error.empty()) {
+                            command.clear();
+                            commandErrors.emplace(&cfg, std::format("building the std module for {}: {}", cfg.target, error));
+                        }
                     }
-                } catch (const std::exception&) {
-                    command.clear();  // surfaced per file as an AST reason
+                } catch (const std::exception& e) {
+                    command.clear();
+                    commandErrors.emplace(&cfg, std::format("assembling the compile command for {}: {}", cfg.target, e.what()));
                 }
                 commands.emplace(&cfg, std::move(command));
             };
@@ -1200,6 +1208,11 @@ format` applies it to disk, and `crafter-build lint` reports where it would.
             // decides what is safe to touch. Skip it and make the run fail.
             if (rule->needsAst) {
                 if (opts.noAst) continue;
+                if (auto failed = commandErrors.find(owner); failed != commandErrors.end()) {
+                    astFailures.emplace(file, failed->second);
+                    skippedAstRules.insert(rule->name);
+                    continue;
+                }
                 // No compile command means this file is not a translation unit
                 // of the build graph — project.cpp, which LoadProject compiles
                 // with its own flags, or a header. A semantic rule does not