diff --git a/include/mrdocs/Support/Report.hpp b/include/mrdocs/Support/Report.hpp
index 127e28096df..f17285123c5 100644
--- a/include/mrdocs/Support/Report.hpp
+++ b/include/mrdocs/Support/Report.hpp
@@ -34,7 +34,7 @@
 */
 namespace mrdocs::report {
 
-/** Severity levels attached to reported messags.
+/** Severity levels attached to reported messages.
 */
 enum class Level
 {
@@ -103,11 +103,10 @@ Level
 getMinimumLevel() noexcept;
 
 /** If true, source location information will be
-    printed with warnings, errors, and fatal messages.
+    printed.
 
-    @param b true to enable source location
-    information, false to disable it. The default
-    value is true.
+    @param b true to enable the bug report details,
+    false to disable them. The default value is true.
 */
 MRDOCS_DECL
 void
@@ -133,8 +132,13 @@ print(
     trailing newline will be added to the
     message automatically.
 
-    @param loc The source location of the report.
-    If this value is null, no location is printed.
+    @param loc The source location a bug report
+    should carry. If this value is null, the message
+    is printed on its own, without the bug report
+    details.
+
+    @param e The error the message reports, when
+    there is one. Only read when `loc` is not null.
 */
 MRDOCS_DECL
 void
@@ -179,38 +183,42 @@ struct Located
     column widths) from the public reporting API.
 */
 namespace detail {
+// `withBugDetails` says whether the message reports a MrDocs defect. Only
+// then is the location where MrDocs raised it worth printing, along with
+// the rest of what a bug report needs. A message about the user's input
+// does not contain such info.
 template<class Arg0, class... Args>
 requires (!std::same_as<std::decay_t<Arg0>, Error>)
 void
 log_impl(
     Level level,
+    bool withBugDetails,
     Located<std::string_view> fs,
     Arg0&& arg0,
     Args&&... args)
 {
   std::string str =
       std::vformat(fs.value, std::make_format_args(arg0, args...));
-  return print(level, str, &fs.where);
+  return print(level, str, withBugDetails ? &fs.where : nullptr);
 }
 
 template<class... Args>
 void
 log_impl(
     Level level,
+    bool withBugDetails,
     Located<std::string_view> fs,
     Error const& e,
     Args&&... args)
 {
-    // When the message is an error, we send split
-    // the information relevant to the user from
-    // the information relevant for bug tracking
-    // so that users can understand the message.
+    // The reason is what went wrong; where MrDocs raised it belongs to the
+    // bug report details, so the message carries the reason alone.
     std::string str =
         std::vformat(fs.value, std::make_format_args(e.reason(), args...));
     return print(
         level,
         str,
-        &fs.where,
+        withBugDetails ? &fs.where : nullptr,
         &e);
 }
 
@@ -218,10 +226,11 @@ inline
 void
 log_impl(
     Level level,
+    bool withBugDetails,
     Located<std::string_view> fs)
 {
   std::string str(fs.value);
-  return print(level, str, &fs.where);
+  return print(level, str, withBugDetails ? &fs.where : nullptr);
 }
 }
 
@@ -246,6 +255,7 @@ log(
 {
     return detail::log_impl(
         level,
+        false,
         fs,
         std::forward<Args>(args)...);
 }
@@ -328,6 +338,29 @@ fatal(
     return log(Level::fatal, format, std::forward<Args>(args)...);
 }
 
+/** Emit an error that reports a defect in MrDocs itself.
+
+    The message is followed by the version and the source location a bug
+    report needs. Use it where MrDocs reached a state it does not handle.
+    A mistake in the user's input is not a bug in MrDocs, so it goes
+    through the other reporting functions.
+
+    @param format fmt-style format string.
+    @param args Arguments substituted into the format string.
+*/
+template<class... Args>
+void
+bug(
+    Located<std::string_view> format,
+    Args&&... args)
+{
+    return detail::log_impl(
+        Level::error,
+        true,
+        format,
+        std::forward<Args>(args)...);
+}
+
 } // mrdocs
 
 #endif
diff --git a/src/mrdocs/AST/ASTVisitor.cpp b/src/mrdocs/AST/ASTVisitor.cpp
index 1e9fc460597..f0b969e24c2 100644
--- a/src/mrdocs/AST/ASTVisitor.cpp
+++ b/src/mrdocs/AST/ASTVisitor.cpp
@@ -2221,7 +2221,7 @@ addMember(
         addMember(I.Members.Macros, *U);
         return;
     }
-    report::error("Cannot push {} of type {} into members of namespace {}",
+    report::bug("Cannot push {} of type {} into members of namespace {}",
         Member.Name,
         mrdocs::toString(Member.Kind),
         I.Name);
@@ -2311,7 +2311,7 @@ addMember(RecordTranche& T, Symbol const& Member)
         addMember(T.Usings, *U);
         return;
     }
-    report::error("Cannot push {} of type {} into tranche",
+    report::bug("Cannot push {} of type {} into tranche",
         Member.Name,
         mrdocs::toString(Member.Kind));
 }
@@ -2325,7 +2325,7 @@ addMember(EnumSymbol& I, Symbol const& Member) const
         addMember(I.Constants, *U);
         return;
     }
-    report::error("Cannot push {} of type {} into members of enum {}",
+    report::bug("Cannot push {} of type {} into members of enum {}",
         Member.Name,
         mrdocs::toString(Member.Kind),
         I.Name);
@@ -2340,7 +2340,7 @@ addMember(OverloadsSymbol& I, Symbol const& Member) const
         addMember(I.Members, Member);
         return;
     }
-    report::error("Cannot push {} of type {} into members of enum {}",
+    report::bug("Cannot push {} of type {} into members of overload set {}",
         Member.Name,
         mrdocs::toString(Member.Kind),
         I.Name);
diff --git a/src/mrdocs/AST/ExtractDocComment.cpp b/src/mrdocs/AST/ExtractDocComment.cpp
index bb6c15609da..7d2d8fece79 100644
--- a/src/mrdocs/AST/ExtractDocComment.cpp
+++ b/src/mrdocs/AST/ExtractDocComment.cpp
@@ -200,7 +200,7 @@ convertDirection(clang::comments::ParamCommandPassDirection d)
     case D::InOut:
         return doc::ParamDirection::inout;
     }
-    report::error(
+    report::bug(
         "error: unsupported ParamCommandPassDirection <{}>",
         static_cast<int>(d));
     MRDOCS_UNREACHABLE();
@@ -219,7 +219,7 @@ convertCopydoc(unsigned id)
     case T::KCI_copydetails:
         return doc::Parts::description;
     default:
-        report::error("error: unsupported CommandTrait id <{}>", id);
+        report::bug("error: unsupported CommandTrait id <{}>", id);
         MRDOCS_UNREACHABLE();
     }
 }
@@ -793,7 +793,7 @@ class DocCommentVisitor
         Expected<doc::TableCell> cellExp = parseTableCell(sub);
         if (!cellExp)
         {
-            warnNear(s, cellExp.error().message());
+            warnNear(s, cellExp.error().reason());
             return;
         }
         row.Cells.push_back(std::move(*cellExp));
@@ -894,7 +894,7 @@ class DocCommentVisitor
         Expected<doc::TableRow> rowExp = parseTableRow(sub);
         if (!rowExp)
         {
-            warnNear(s, rowExp.error().message());
+            warnNear(s, rowExp.error().reason());
             return;
         }
         // Skip rows whose cells all failed to parse: a row with
@@ -1049,7 +1049,7 @@ class DocCommentVisitor
         Expected<doc::TableBlock> tbExp = parseTable(cur);
         if (!tbExp)
         {
-            warnNear(C, tbExp.error().message());
+            warnNear(C, tbExp.error().reason());
             return;
         }
         // A table with no rows (e.g., because every row's content
@@ -1185,7 +1185,7 @@ class DocCommentVisitor
             // written; the rest of the phrase follows as ordinary text.
             if (isSupportedHTMLTag(C->getTagName()))
             {
-                warnOnce(filename, loc.getLine(), compsExp.error().message());
+                warnOnce(filename, loc.getLine(), compsExp.error().reason());
             }
             emplaceInline<doc::TextInline>(
                 C->hasTrailingNewline(),
@@ -1210,7 +1210,7 @@ class DocCommentVisitor
                 // problem in the user's doc comment, not in Mr.Docs: warn
                 // with the location and keep the text instead of failing
                 // the whole run with an internal-error banner.
-                warnOnce(filename, loc.getLine(), r.error().message());
+                warnOnce(filename, loc.getLine(), r.error().reason());
                 emplaceInline<doc::TextInline>(
                     C->hasTrailingNewline(),
                     ensureUTF8(std::move(comps.text)));
@@ -1276,7 +1276,7 @@ class DocCommentVisitor
             auto srcAttr = getAttr("src");
             if (!srcAttr)
             {
-                warnOnce(filename, loc.getLine(), srcAttr.error().message());
+                warnOnce(filename, loc.getLine(), srcAttr.error().reason());
                 return;
             }
             std::string alt = getAttr("alt").value_or(std::string());
@@ -1360,7 +1360,7 @@ class DocCommentVisitor
             warnOnce(
                 files::makePosixStyle(loc.getFilename()),
                 loc.getLine(),
-                r.error().message());
+                r.error().reason());
         }
         else if (comps.tag == "em")
         {
@@ -1761,7 +1761,7 @@ class DocCommentVisitor
         case T::KCI_copybrief:
         case T::KCI_copydetails:
         case T::KCI_copydoc:
-            report::error(
+            report::bug(
                 "error: inline command {} should be handled elsewhere",
                 cmd->Name);
             MRDOCS_UNREACHABLE();
diff --git a/src/mrdocs/Config.cpp b/src/mrdocs/Config.cpp
index d615109b48d..a1391f4dc0d 100644
--- a/src/mrdocs/Config.cpp
+++ b/src/mrdocs/Config.cpp
@@ -1119,9 +1119,7 @@ struct ConfigSchemaVisitor {
         MRDOCS_TRY(
             std::string_view const baseDir,
             getBaseDir(referenceDirKey, dirs, settings));
-        if (pos != std::string::npos) {
-            value = value.substr(pos + 1);
-        }
+        value = pos != std::string::npos ? value.substr(pos + 1) : ".";
         return std::string(baseDir);
     }
 };
diff --git a/src/mrdocs/Corpus.cpp b/src/mrdocs/Corpus.cpp
index b5c404eb50c..33f85a1df35 100644
--- a/src/mrdocs/Corpus.cpp
+++ b/src/mrdocs/Corpus.cpp
@@ -522,8 +522,7 @@ Corpus::build(
         {
             return Unexpected(err);
         }
-        report::warn(
-            "Warning: mapping failed because ", err);
+        report::warn("Mapping failed: {}", err);
     }
 
     MRDOCS_TRY(auto results, context.results());
diff --git a/src/mrdocs/Engines/JavaScript.cpp b/src/mrdocs/Engines/JavaScript.cpp
index 57ef8e371d2..ca44eddeb3a 100644
--- a/src/mrdocs/Engines/JavaScript.cpp
+++ b/src/mrdocs/Engines/JavaScript.cpp
@@ -305,7 +305,7 @@ invokeHelper(Value const& fn, dom::Array const& args)
     auto ret = fn.apply(callArgs);
     if (!ret)
     {
-        return Unexpected(dom::Error(std::string(ret.error().message())));
+        return Unexpected(dom::Error(std::string(ret.error().reason())));
     }
     return ret->getDom();
 }
diff --git a/src/mrdocs/Extensions/ExtensionRegistry.cpp b/src/mrdocs/Extensions/ExtensionRegistry.cpp
index e6b7b498ec9..7bb820b3dc7 100644
--- a/src/mrdocs/Extensions/ExtensionRegistry.cpp
+++ b/src/mrdocs/Extensions/ExtensionRegistry.cpp
@@ -95,7 +95,7 @@ ExtensionRegistry::applyTransforms(Corpus& corpus, Config const& config) const
             {
                 return Unexpected(formatError(
                     "extension transform '{}': {}",
-                    id, invoked.error().message()));
+                    id, invoked.error().reason()));
             }
         }
     }
diff --git a/src/mrdocs/Extensions/JsBinding.cpp b/src/mrdocs/Extensions/JsBinding.cpp
index 4c7cb5522cd..3c7a5d33d2b 100644
--- a/src/mrdocs/Extensions/JsBinding.cpp
+++ b/src/mrdocs/Extensions/JsBinding.cpp
@@ -189,7 +189,7 @@ loadJsExtensions(std::string const& scriptPath, Config const& config)
     if (!ran.has_value())
     {
         return Unexpected(formatError(
-            "extension '{}': {}", scriptPath, ran.error().message()));
+            "extension '{}': {}", scriptPath, ran.error().reason()));
     }
 
     if (loaded.transforms.empty() && loaded.generators.empty())
diff --git a/src/mrdocs/Generators/hbs/Builder.cpp b/src/mrdocs/Generators/hbs/Builder.cpp
index a6d89884b2d..0e196a54a99 100644
--- a/src/mrdocs/Generators/hbs/Builder.cpp
+++ b/src/mrdocs/Generators/hbs/Builder.cpp
@@ -360,7 +360,7 @@ registerUserJsHelpers(
         {
             return Unexpected(formatError(
                 "Error loading utility {}: {}",
-                utilPath, exp.error().message()));
+                utilPath, exp.error().reason()));
         }
     }
 
@@ -417,7 +417,7 @@ registerUserLuaHelpers(
         {
             return Unexpected(formatError(
                 "Error loading utility {}: {}",
-                utilPath, exp.error().message()));
+                utilPath, exp.error().reason()));
         }
     }
 
@@ -680,7 +680,7 @@ operator()(std::ostream& os, T const& I)
             // Reuse the already-built context to avoid recomputing DOM data.
             if (auto exp = callTemplate(os, templateFile, ctx); !exp)
             {
-                return Unexpected(dom::Error(std::string(exp.error().message())));
+                return Unexpected(dom::Error(std::string(exp.error().reason())));
             }
             return {};
         }));
@@ -715,7 +715,7 @@ renderWrapped(
     ctx.set("contents",
             dom::makeInvocable([&](dom::Value const &) -> dom::Expected<dom::Value> {
               if (auto exp = contentsCb(); !exp) {
-                return Unexpected(dom::Error(std::string(exp.error().message())));
+                return Unexpected(dom::Error(std::string(exp.error().reason())));
               }
               return {};
             }));
diff --git a/src/mrdocs/Generators/script/ScriptGenerator.cpp b/src/mrdocs/Generators/script/ScriptGenerator.cpp
index f7c93349cd1..ba63cb1692f 100644
--- a/src/mrdocs/Generators/script/ScriptGenerator.cpp
+++ b/src/mrdocs/Generators/script/ScriptGenerator.cpp
@@ -129,7 +129,7 @@ buildOutputApi(OutputSink& sink)
                         doAppend);
                     !wrote)
                 {
-                    result = Unexpected(dom::Error(std::string(wrote.error().message())));
+                    result = Unexpected(dom::Error(std::string(wrote.error().reason())));
                 }
                 else
                 {
@@ -212,7 +212,7 @@ build(Corpus const& corpus, Config const& config) const
     if (!invoked)
     {
         result = Unexpected(formatError(
-            "generator '{}': {}", id_, invoked.error().message()));
+            "generator '{}': {}", id_, invoked.error().reason()));
     }
     return result;
 }
diff --git a/src/mrdocs/Support/Report.cpp b/src/mrdocs/Support/Report.cpp
index 22b340e8fee..8d12a82afb2 100644
--- a/src/mrdocs/Support/Report.cpp
+++ b/src/mrdocs/Support/Report.cpp
@@ -107,20 +107,6 @@ print(
 
 //------------------------------------------------
 
-Level
-getLevel(unsigned level) noexcept
-{
-    switch(level)
-    {
-    case 0: return Level::debug;
-    case 1: return Level::info;
-    case 2: return Level::warn;
-    case 3: return Level::error;
-    default:
-        return Level::fatal;
-    }
-}
-
 constexpr
 llvm::raw_ostream::Colors
 getLevelColor(Level level)
diff --git a/src/mrdocs/Support/ReportImpl.hpp b/src/mrdocs/Support/ReportImpl.hpp
index 77404709327..8c802b1839d 100644
--- a/src/mrdocs/Support/ReportImpl.hpp
+++ b/src/mrdocs/Support/ReportImpl.hpp
@@ -94,16 +94,11 @@ class separator
 
 //------------------------------------------------
 
-/** Return a level from an integer.
-*/
-MRDOCS_DECL
-Level
-getLevel(
-    unsigned level) noexcept;
-
 /** Formatted reporting to a live stream.
 
-    A trailing newline will be added automatically.
+    A trailing newline will be added automatically. If a location is present,
+    the message will be considered to be for a MrDocs defect, and will contain
+    an invite to file a bug report.
 */
 MRDOCS_DECL
 void
@@ -113,20 +108,6 @@ call_impl(
     source_location const* loc,
     Error const* e = nullptr);
 
-/** Formatted reporting to a live stream.
-
-    A trailing newline will be added automatically.
-*/
-inline void
-call(
-    Level level,
-    std::function<void(llvm::raw_ostream&)> f,
-    source_location const& loc =
-        source_location::current())
-{
-    call_impl(level, std::move(f), &loc);
-}
-
 } // report
 
 } // mrdocs
diff --git a/tests/golden/TestMain.cpp b/tests/golden/TestMain.cpp
index 0ae40eb8c4a..64ed8a3295c 100644
--- a/tests/golden/TestMain.cpp
+++ b/tests/golden/TestMain.cpp
@@ -136,13 +136,13 @@ accepted and applied like the mrdocs tool.
     return EXIT_SUCCESS;
 }
 
-#ifdef _NDEBUG
+#ifdef NDEBUG
 static void reportUnhandledException(
     std::exception const& ex)
 {
     namespace sys = llvm::sys;
 
-    report::error("Unhandled exception: {}\n", ex.what());
+    report::bug("Unhandled exception: {}\n", ex.what());
     sys::PrintStackTrace(llvm::errs());
 }
 #endif
@@ -152,7 +152,7 @@ static void reportUnhandledException(
 
 int main(int argc, char const** argv)
 {
-#ifndef _NDEBUG
+#ifndef NDEBUG
     return mrdocs::test_main(argc, argv);
 #else
     try
diff --git a/tests/unit/Config.cpp b/tests/unit/Config.cpp
new file mode 100644
index 00000000000..d60f8477d8f
--- /dev/null
+++ b/tests/unit/Config.cpp
@@ -0,0 +1,57 @@
+//
+// Licensed under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// Copyright (c) 2026 Gennaro Prota (gennaro.prota@gmail.com)
+//
+// Official repository: https://github.com/cppalliance/mrdocs
+//
+
+#include <mrdocs/Config.hpp>
+#include <mrdocs/Support/Filesystem/Path.hpp>
+#include <mrdocs/Support/Filesystem/Temp.hpp>
+#include <test_suite/test_suite.hpp>
+#include <fstream>
+#include <string>
+
+namespace mrdocs {
+
+struct ConfigTest
+{
+    void
+    testSourceRootDefaultsToConfigDir()
+    {
+        ScopedTempDirectory td("mrdocs-config");
+        BOOST_TEST(td);
+        // `addons` must name a directory that exists, and nothing reads
+        // it here, so an empty one will do.
+        std::string const addonsDir = files::appendPath(td.path(), "addons");
+        BOOST_TEST(files::createDirectory(addonsDir).has_value());
+        std::string const configPath =
+            files::appendPath(td.path(), "mrdocs.yml");
+        {
+            std::ofstream os(configPath, std::ios::binary | std::ios::trunc);
+            os << "addons: addons\n";
+        }
+
+        Config config;
+        ReferenceDirectories const dirs;
+        Expected<void> const loaded =
+            Config::load_file(config, configPath, dirs);
+        BOOST_TEST(loaded.has_value());
+        BOOST_TEST(config.sourceRoot == files::makePosixStyle(td.path()));
+    }
+
+    void
+    run()
+    {
+        testSourceRootDefaultsToConfigDir();
+    }
+};
+
+TEST_SUITE(
+    ConfigTest,
+    "clang.mrdocs.Config");
+
+} // mrdocs
diff --git a/tools/mrdocs/src/Main.cpp b/tools/mrdocs/src/Main.cpp
index 4595c121ab6..67af1688444 100644
--- a/tools/mrdocs/src/Main.cpp
+++ b/tools/mrdocs/src/Main.cpp
@@ -413,7 +413,7 @@ mrdocs_main(int argc, char const** argv)
     auto res = getReferenceDirectories(execPath);
     if (!res)
     {
-        report::fatal("Failed to determine reference directories: {}", res.error().message());
+        report::fatal("Failed to determine reference directories: {}", res.error());
         return EXIT_FAILURE;
     }
     auto dirs = *std::move(res);
@@ -421,7 +421,7 @@ mrdocs_main(int argc, char const** argv)
     auto expConfigPath = getConfigPath(dirs, cl);
     if (!expConfigPath)
     {
-        report::fatal("Failed to determine config path: {}", expConfigPath.error().message());
+        report::fatal("Failed to determine config path: {}", expConfigPath.error());
         return EXIT_FAILURE;
     }
     auto configPath = *std::move(expConfigPath);
@@ -439,7 +439,7 @@ mrdocs_main(int argc, char const** argv)
     return EXIT_SUCCESS;
 }
 
-#ifdef _NDEBUG
+#ifdef NDEBUG
 static
 void
 reportUnhandledException(
@@ -447,7 +447,7 @@ reportUnhandledException(
 {
     namespace sys = llvm::sys;
 
-    report::fatal("Unhandled exception: {}\n", ex.what());
+    report::bug("Unhandled exception: {}\n", ex.what());
     sys::PrintStackTrace(llvm::errs());
 }
 #endif
@@ -457,7 +457,7 @@ reportUnhandledException(
 int
 main(int argc, char const** argv)
 {
-#ifndef _NDEBUG
+#ifndef NDEBUG
     return mrdocs::mrdocs_main(argc, argv);
 #else
     try