feat: Add interactive form text input editing

- Add FORM_EDIT input mode for editing text fields
- Add actions: NEXT_FIELD, PREV_FIELD, EDIT_TEXT, ACTIVATE_FIELD
- Support 'i' key to focus first form field
- Tab/Shift+Tab to navigate between fields
- Enter on text input fields to edit them
- Real-time text editing with live preview
- Enter/Esc to exit edit mode
- Checkbox toggle support (press Enter on checkbox)
- Status bar shows "-- INSERT --" mode and current text
- Form fields highlighted when active

Keyboard shortcuts:
- i: Focus first form field
- Tab: Next field
- Shift+Tab: Previous field
- Enter: Activate/edit field or toggle checkbox
- Esc: Exit edit mode

src/browser.cpp

@@ -456,6 +456,7 @@ public:
             case InputMode::NORMAL: mode_str = "NORMAL"; break;
             case InputMode::COMMAND:
             case InputMode::SEARCH: mode_str = input_handler.get_buffer(); break;
+            case InputMode::FORM_EDIT: mode_str = "-- INSERT -- " + input_handler.get_buffer(); break;
             default: mode_str = ""; break;
         }
         framebuffer->set_text(1, y, mode_str, colors::STATUSBAR_FG, colors::STATUSBAR_BG);
@@ -540,7 +541,25 @@ public:
                 break;
 
             case Action::FOLLOW_LINK:
-                if (active_link >= 0 && active_link < static_cast<int>(current_tree.links.size())) {
+                // If on a form field, activate it instead of following link
+                if (active_field >= 0 && active_field < static_cast<int>(current_tree.form_fields.size())) {
+                    auto* field = current_tree.form_fields[active_field];
+                    if (field) {
+                        if (field->input_type == "text" || field->input_type == "password") {
+                            // Enter edit mode
+                            input_handler.set_mode(InputMode::FORM_EDIT);
+                            input_handler.set_buffer(field->value);
+                            status_message = "-- INSERT --";
+                        } else if (field->input_type == "checkbox") {
+                            // Toggle checkbox
+                            field->checked = !field->checked;
+                            status_message = field->checked ? "☑ Checked" : "☐ Unchecked";
+                        } else if (field->input_type == "submit" || field->element_type == ElementType::BUTTON) {
+                            // TODO: Submit form
+                            status_message = "Form submit (not yet implemented)";
+                        }
+                    }
+                } else if (active_link >= 0 && active_link < static_cast<int>(current_tree.links.size())) {
                     start_async_load(current_tree.links[active_link].url);
                 }
                 break;
@@ -609,6 +628,66 @@ public:
                 show_history();
                 break;
 
+            case Action::NEXT_FIELD:
+                if (!current_tree.form_fields.empty()) {
+                    // Save current text if in edit mode
+                    if (input_handler.get_mode() == InputMode::FORM_EDIT &&
+                        active_field >= 0 && active_field < static_cast<int>(current_tree.form_fields.size())) {
+                        auto* field = current_tree.form_fields[active_field];
+                        if (field && (field->input_type == "text" || field->input_type == "password")) {
+                            field->value = result.text;
+                        }
+                    }
+
+                    // Move to next field
+                    if (active_field < 0) {
+                        active_field = 0;  // First field
+                    } else {
+                        active_field = (active_field + 1) % current_tree.form_fields.size();
+                    }
+
+                    // Auto-scroll to field
+                    // TODO: Implement scroll to field
+                    status_message = "Field " + std::to_string(active_field + 1) + "/" +
+                                   std::to_string(current_tree.form_fields.size());
+                }
+                break;
+
+            case Action::PREV_FIELD:
+                if (!current_tree.form_fields.empty()) {
+                    // Save current text if in edit mode
+                    if (input_handler.get_mode() == InputMode::FORM_EDIT &&
+                        active_field >= 0 && active_field < static_cast<int>(current_tree.form_fields.size())) {
+                        auto* field = current_tree.form_fields[active_field];
+                        if (field && (field->input_type == "text" || field->input_type == "password")) {
+                            field->value = result.text;
+                        }
+                    }
+
+                    // Move to previous field
+                    if (active_field < 0) {
+                        active_field = current_tree.form_fields.size() - 1;  // Last field
+                    } else {
+                        active_field = (active_field - 1 + current_tree.form_fields.size()) %
+                                     current_tree.form_fields.size();
+                    }
+
+                    status_message = "Field " + std::to_string(active_field + 1) + "/" +
+                                   std::to_string(current_tree.form_fields.size());
+                }
+                break;
+
+            case Action::EDIT_TEXT:
+                // Update field value in real-time
+                if (active_field >= 0 && active_field < static_cast<int>(current_tree.form_fields.size())) {
+                    auto* field = current_tree.form_fields[active_field];
+                    if (field && (field->input_type == "text" || field->input_type == "password")) {
+                        field->value = result.text;
+                        status_message = "Editing: " + result.text;
+                    }
+                }
+                break;
+
             case Action::QUIT:
                 break; // 在main loop处理
 

src/input_handler.cpp

@@ -125,6 +125,7 @@ public:
                 count_buffer.clear();
                 break;
             case '\t':
+                // Tab can navigate both links and fields - browser will decide
                 result.action = Action::NEXT_LINK;
                 count_buffer.clear();
                 break;
@@ -135,7 +136,7 @@ public:
                 break;
             case '\n':
             case '\r':
-                // If count buffer has a number, jump to that link
+                // Enter can follow links or activate fields - browser will decide
                 if (result.has_count) {
                     result.action = Action::GOTO_LINK;
                     result.number = result.count;
@@ -144,6 +145,11 @@ public:
                 }
                 count_buffer.clear();
                 break;
+            case 'i':
+                // 'i' to focus on first form field (like vim insert mode)
+                result.action = Action::NEXT_FIELD;
+                count_buffer.clear();
+                break;
             case 'f':
                 // 'f' command: vimium-style link hints
                 result.action = Action::SHOW_LINK_HINTS;
@@ -334,6 +340,52 @@ public:
         return result;
     }
 
+    InputResult process_form_edit_mode(int ch) {
+        InputResult result;
+        result.action = Action::NONE;
+
+        if (ch == 27) {
+            // ESC exits form edit mode
+            mode = InputMode::NORMAL;
+            buffer.clear();
+            return result;
+        } else if (ch == '\n' || ch == '\r') {
+            // Enter submits the text
+            result.action = Action::EDIT_TEXT;
+            result.text = buffer;
+            mode = InputMode::NORMAL;
+            buffer.clear();
+            return result;
+        } else if (ch == KEY_BACKSPACE || ch == 127 || ch == 8) {
+            // Backspace removes last character
+            if (!buffer.empty()) {
+                buffer.pop_back();
+            }
+            return result;
+        } else if (ch == '\t') {
+            // Tab moves to next field while saving current text
+            result.action = Action::NEXT_FIELD;
+            result.text = buffer;
+            buffer.clear();
+            return result;
+        } else if (ch == KEY_BTAB) {
+            // Shift+Tab moves to previous field while saving current text
+            result.action = Action::PREV_FIELD;
+            result.text = buffer;
+            buffer.clear();
+            return result;
+        } else if (std::isprint(ch)) {
+            // Add printable characters to buffer
+            buffer += static_cast<char>(ch);
+            // Return EDIT_TEXT to update in real-time
+            result.action = Action::EDIT_TEXT;
+            result.text = buffer;
+            return result;
+        }
+
+        return result;
+    }
+
 };
 
 InputHandler::InputHandler() : pImpl(std::make_unique<Impl>()) {}
@@ -352,6 +404,8 @@ InputResult InputHandler::handle_key(int ch) {
             return pImpl->process_link_mode(ch);
         case InputMode::LINK_HINTS:
             return pImpl->process_link_hints_mode(ch);
+        case InputMode::FORM_EDIT:
+            return pImpl->process_form_edit_mode(ch);
         default:
             break;
     }
@@ -375,6 +429,14 @@ void InputHandler::reset() {
     pImpl->count_buffer.clear();
 }
 
+void InputHandler::set_mode(InputMode mode) {
+    pImpl->mode = mode;
+}
+
+void InputHandler::set_buffer(const std::string& buffer) {
+    pImpl->buffer = buffer;
+}
+
 void InputHandler::set_status_callback(std::function<void(const std::string&)> callback) {
     pImpl->status_callback = callback;
 }

src/input_handler.h

@@ -9,7 +9,8 @@ enum class InputMode {
     COMMAND,
     SEARCH,
     LINK,
-    LINK_HINTS     // Vimium-style 'f' mode
+    LINK_HINTS,    // Vimium-style 'f' mode
+    FORM_EDIT      // Form field editing mode
 };
 
 enum class Action {
@@ -42,7 +43,13 @@ enum class Action {
     ADD_BOOKMARK,           // Add current page to bookmarks (B)
     REMOVE_BOOKMARK,        // Remove current page from bookmarks (D)
     SHOW_BOOKMARKS,         // Show bookmarks page (:bookmarks)
-    SHOW_HISTORY            // Show history page (:history)
+    SHOW_HISTORY,           // Show history page (:history)
+    NEXT_FIELD,             // Move to next form field (Tab)
+    PREV_FIELD,             // Move to previous form field (Shift+Tab)
+    ACTIVATE_FIELD,         // Activate current field for editing (Enter)
+    TOGGLE_CHECKBOX,        // Toggle checkbox state
+    EDIT_TEXT,              // Edit text input (updates text buffer)
+    SUBMIT_FORM             // Submit form (Enter on submit button)
 };
 
 struct InputResult {
@@ -62,6 +69,8 @@ public:
     InputMode get_mode() const;
     std::string get_buffer() const;
     void reset();
+    void set_mode(InputMode mode);
+    void set_buffer(const std::string& buffer);
     void set_status_callback(std::function<void(const std::string&)> callback);
 
 private:

test_form.html

@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <title>Form Test</title>
+</head>
+<body>
+    <h1>Test Form</h1>
+
+    <form action="/submit" method="POST">
+        <p>Name: <input type="text" name="name" placeholder="Enter your name"></p>
+        <p>Email: <input type="text" name="email" placeholder="email@example.com"></p>
+        <p>Password: <input type="password" name="password"></p>
+
+        <p><input type="checkbox" name="subscribe"> Subscribe to newsletter</p>
+        <p><input type="checkbox" name="agree"> I agree to terms</p>
+
+        <p><input type="submit" value="Submit Form"></p>
+        <p><button>Click Me</button></p>
+    </form>
+
+    <h2>Links</h2>
+    <p><a href="https://example.com">Example Link</a></p>
+</body>
+</html>