Step 187: in-editor help panel

PROGRESS.md

@@ -534,4 +534,5 @@ Sprint 5 in progress. Step 141 (Emacs daemon with user config) done. Next: Step
 | 2026-02-10 | Codex | Step 184: First-run wizard (layout/theme/keybindings + get-started actions) wired on missing session. 2/2 tests pass (step184_test, step184_integration_test). |
 | 2026-02-10 | Codex | Step 185: Contextual feature hints with persistence + dismiss/disable. 2/2 tests pass (step185_test, step185_integration_test). |
 | 2026-02-10 | Codex | Step 186: Keyboard shortcut reference panel with filter and live bindings. 2/2 tests pass (step186_test, step186_integration_test). |
+| 2026-02-10 | Codex | Step 187: In-editor help panel window wired from menu with Markdown renderer reuse. 2/2 tests pass (step187_test, step187_integration_test). |
 | 2026-02-10 | Codex | Step 166: Extract main.cpp into panel headers marked complete (already implemented). step166_test passes; file_limits_test 4/4 passes. |

editor/CMakeLists.txt

@@ -1093,6 +1093,13 @@ add_executable(step186_integration_test tests/step186_integration_test.cpp)
 target_include_directories(step186_integration_test PRIVATE src)
 target_link_libraries(step186_integration_test PRIVATE nlohmann_json::nlohmann_json)
 
+add_executable(step187_test tests/step187_test.cpp)
+target_include_directories(step187_test PRIVATE src)
+
+add_executable(step187_integration_test tests/step187_integration_test.cpp)
+target_include_directories(step187_integration_test PRIVATE src)
+target_link_libraries(step187_integration_test PRIVATE nlohmann_json::nlohmann_json)
+
 find_package(SDL2 CONFIG REQUIRED)
 find_package(OpenGL REQUIRED)
 find_package(glad CONFIG REQUIRED)

editor/src/main.cpp

@@ -29,6 +29,7 @@
 #include "panels/EditorPanel.h"
 #include "panels/BottomPanel.h"
 #include "panels/StatusBarPanel.h"
+#include "panels/HelpPanelWindow.h"
 
 static std::string emacsChordForEvent(SDL_Keycode sym, Uint16 mods) {
     std::string base;
@@ -383,6 +384,7 @@ int main(int, char**) {
         renderFeatureHintBar(state.featureHints, state.workspaceRoot);
         static ShortcutReferenceState shortcutPanel;
         renderShortcutReference(state, shortcutPanel);
+        renderHelpPanelWindow(state);
         state.notifications.renderHistoryWindow([&](const Notification& note) {
             if (note.hasTarget) state.navigateToTarget(note.target);
         });

editor/src/panels/HelpPanelWindow.h

@@ -0,0 +1,12 @@
+#pragma once
+
+#include "../EditorState.h"
+
+static void renderHelpPanelWindow(EditorState& state) {
+    if (!state.ui.showHelpPanel) return;
+    ImGui::Begin("Documentation", &state.ui.showHelpPanel);
+    ImGui::PushFont(state.uiFont);
+    renderHelpPanel(state.helpPanel, state.workspaceRoot, state.monoFont);
+    ImGui::PopFont();
+    ImGui::End();
+}

editor/src/panels/MenuBarPanel.h

@@ -210,6 +210,10 @@ static void renderMenuBar(EditorState& state) {
         }
         ImGui::EndMenu();
     }
+    if (ImGui::BeginMenu("Help")) {
+        ImGui::MenuItem("Documentation", nullptr, &state.ui.showHelpPanel);
+        ImGui::EndMenu();
+    }
 
     const bool canProject = state.activeAST() != nullptr;
     ImGui::SameLine();

editor/src/state/UIFlags.h

@@ -11,6 +11,7 @@ struct UIFlags {
     bool showSettingsPanel = false;
     bool showFirstRunWizard = false;
     bool showShortcutReference = false;
+    bool showHelpPanel = false;
     int bottomTab = 0; // 0=Output,1=AST,2=Highlighted
     LayoutPreset layoutPreset = LayoutPreset::VSCode;
 };

editor/tests/step187_integration_test.cpp

@@ -0,0 +1,14 @@
+// Step 187: Help panel flag integration checks.
+
+#include <cassert>
+
+#include "state/UIFlags.h"
+
+int main() {
+    UIFlags flags;
+    flags.showHelpPanel = true;
+    assert(flags.showHelpPanel == true);
+
+    printf("step187_integration_test: all assertions passed\n");
+    return 0;
+}

editor/tests/step187_test.cpp

@@ -0,0 +1,25 @@
+// Step 187: In-editor help panel checks.
+
+#include <cassert>
+#include <fstream>
+#include <string>
+
+static std::string readFile(const std::string& path) {
+    std::ifstream f(path);
+    if (!f.is_open()) return {};
+    return std::string((std::istreambuf_iterator<char>(f)),
+                       std::istreambuf_iterator<char>());
+}
+
+static void assertContains(const std::string& text, const std::string& needle) {
+    assert(text.find(needle) != std::string::npos);
+}
+
+int main() {
+    const std::string help = readFile("src/panels/HelpPanelWindow.h");
+    assertContains(help, "Documentation");
+    assertContains(help, "renderHelpPanel");
+
+    printf("step187_test: all assertions passed\n");
+    return 0;
+}

sprint6_plan.md

@@ -272,7 +272,7 @@ without being annoying.
   - Export to printable HTML/PDF
   *New:* `ShortcutReference.h`
 
-- [ ] **Step 187: In-editor help system**
+- [x] **Step 187: In-editor help system**
   Help > Documentation opens a dockable panel:
   - Searchable documentation browser
   - Sections: Getting Started, Annotation Reference, Language Support,