feat: watch: try pager mode..

package/c/hmpl/default.nix

@@ -25,7 +25,7 @@ stdenv.mkDerivation {
   '';
 
   meta = {
-    description = "hectic";
+    description = "hmpl";
     license = lib.licenses.mit;
   };
 }

package/c/hmpl/hmpl.c

@@ -66,154 +66,116 @@ void hmpl_render_interpolation_tags(Arena *arena, char **text_ptr, const Json *
   }
 }
 
-// CREATE OR REPLACE FUNCTION common.render_template_loop_blocks(result TEXT, context JSONB)
+// {{item#array}}...{{/array}}
-// RETURNS TEXT LANGUAGE plpgsql AS $$
+void hmpl_render_section_tags(Arena *arena, char **text_ptr, Json *context, const char * const prefix_start, const char * const prefix_end, const char * const separator_pattern) {
-// DECLARE
-//   loop_start INT;
-//   key_end INT;
-//   loop_end INT;
-//   loop_key TEXT;
-//   block TEXT;
-//   rendered_block TEXT;
-//   arr JSONB;
-//   item JSONB;
-//   item_text TEXT;
-// BEGIN
-//   LOOP
-//     loop_start := strpos(result, '{{#');
-//     EXIT WHEN loop_start = 0; -- Exit if no loop start found.
-//     
-//     -- Locate the end of the loop key marker.
-//     key_end := strpos(result, '}}', loop_start);
-//     IF key_end = 0 THEN
-//       RAISE EXCEPTION 'Malformed template: missing closing braces for loop start';
-//     END IF;
-//     
-//     -- Extract the key used for the loop.
-//     loop_key := substr_cloneing(result from loop_start + 3 for key_end - loop_start - 3);
-// 
-//     RAISE DEBUG 'loop key %', loop_key;
-//     
-//     -- Find the matching loop end marker for this key.
-//     loop_end := strpos(result, '{{/#' || loop_key || '}}', key_end);
-//     IF loop_end = 0 THEN
-//       RAISE EXCEPTION 'Malformed template: missing loop end for key %', loop_key;
-//     END IF;
-// 
-//     -- Extract the inner block of the loop.
-//     block := substr_cloneing(result from key_end + 2 for loop_end - key_end - 2);
-// 
-//     -- Retrieve the JSON array from the context for the loop key.
-//     arr := eval_value(context, loop_key);
-//     rendered_block := '';
-//     
-//     -- If an array is found, iterate over each element.
-//     IF arr IS NOT NULL AND jsonb_typeof(arr) = 'array' THEN
-//       FOR item IN SELECT * FROM jsonb_array_elements(arr) LOOP
-//         item_text := block;  -- Begin with the raw block.
-//         IF jsonb_typeof(item) != 'object' THEN
-//           -- Replace interpolation for primitive values.
-//           item_text := replace(item_text, '{{.}}', item::text);
-//         ELSE
-//           -- For object values, iterate over each key/value.
-//           item_text := render_template_interpolations(item_text, item, '.'::CHAR(1));
-//           item_text := render_template_conditions(item_text, item, '.');
-//         END IF;
-//         rendered_block := rendered_block || item_text;
-//       END LOOP;
-//     END IF;
-//     
-//     -- Replace the entire loop block in the result with the rendered content.
-//     result := substr_cloneing(result from 1 for loop_start - 1)
-//               || rendered_block
-//               || substr_cloneing(result from loop_end + char_length('{{/#' || loop_key || '}}'));
-//   END LOOP;
-// 
-//   RETURN result;
-// END $$;
-
-// {{#array_key}}
-void hmpl_render_section_tags(Arena *arena, char **text_ptr, Json *context, const char * const prefix_start, const char * const prefix_end, const char * const separator_pattern){
     raise_debug("hmpl_render_section_tags(%p, %s, <optimized>, %s, %s, %s)", arena, *text_ptr, prefix_start, prefix_end, separator_pattern);
+    
+    // Create search patterns
     char start_pattern[32];
     snprintf(start_pattern, sizeof(start_pattern), "{{%s", prefix_start);
-  int start_pattern_length = strlen(start_pattern);
+    Slice start_slice = slice_create(char, start_pattern, strlen(start_pattern), 0, strlen(start_pattern));
 
-  // TODO: rename close_tag_start_pattern
+    // Create a mutable copy of separator_pattern
-  char end_pattern[32];
+    char separator_copy[32];
-  snprintf(end_pattern, sizeof(end_pattern), "{{%s", prefix_end);
+    strncpy(separator_copy, separator_pattern, sizeof(separator_copy) - 1);
-  int end_pattern_length = strlen(end_pattern);
+    separator_copy[sizeof(separator_copy) - 1] = '\0';
-
+    Slice separator_slice = slice_create(char, separator_copy, strlen(separator_copy), 0, strlen(separator_copy));
-  int separator_pattern_length = strlen(separator_pattern);
+    if (separator_slice.len == 0) {
-  if (!separator_pattern || separator_pattern_length == 0) {
         raise_exception("Unexpected usage: separator pattern cannot be empty");
     }
 
-  int offset = 0;
+    // Create slice for the text
+    Slice text_slice = slice_create(char, *text_ptr, strlen(*text_ptr), 0, strlen(*text_ptr));
+    size_t offset = 0;
 
     while (1) {
-    char *current_text = *text_ptr;
+        // Find tag start
-    char *opening_tag_start = strstr(current_text + offset, start_pattern);
+        char *text_data = (char*)text_slice.data;
-    if (!opening_tag_start)
+        char *opening_tag_start = strstr(text_data + offset, (char*)start_slice.data);
-      break;
+        if (!opening_tag_start) break;
-    int start_index = opening_tag_start - current_text;
-    int relative_key_start = start_index + start_pattern_length;
 
-    char *opening_tag_separator = strstr(opening_tag_start, separator_pattern);
+        // Create slice for separator search
-    if (!opening_tag_start) {
+        size_t start_index = opening_tag_start - text_data;
-      raise_exception("Malformed template: missing separator for section tag or not specifiet name for element");
+        Slice remaining_slice = slice_subslice(text_slice, start_index, text_slice.len - start_index);
+        
+        // Find separator
+        char *opening_tag_separator = strstr((char*)remaining_slice.data, (char*)separator_slice.data);
+        if (!opening_tag_separator) {
+            raise_exception("Malformed template: missing separator for section tag or not specified name for element");
             exit(1);
         }
-    int separator_index = opening_tag_separator - current_text;
-    int element_name_start = separator_index + separator_pattern_length;
         
-    char *opening_tag_end = strstr(opening_tag_separator, "}}");
+        // Extract element name (now before separator)
+        size_t separator_index = opening_tag_separator - (char*)remaining_slice.data;
+        size_t element_name_start = start_slice.len;
+        size_t element_name_length = separator_index;
+        
+        char *element_name = arena_alloc(arena, element_name_length + 1);
+        substr_clone((char*)remaining_slice.data, element_name, element_name_start, element_name_length);
+        element_name[element_name_length] = '\0';
+
+        // Find closing braces
+        Slice after_separator = slice_subslice(remaining_slice, separator_index + separator_slice.len, 
+                                             remaining_slice.len - separator_index - separator_slice.len);
+        char *opening_tag_end = strstr((char*)after_separator.data, "}}");
         if (!opening_tag_end) {
             raise_exception("Malformed template: missing closing braces for section tag");
             exit(1);
         }
-    assert((size_t)opening_tag_end > (size_t)opening_tag_separator);
-    assert((size_t)opening_tag_separator > (size_t)opening_tag_start);
-
-    int key_length = (opening_tag_separator - current_text) - relative_key_start;
-    assert(key_length > 0);
 
+        // Extract key (now after separator)
+        size_t key_start = 0;
+        size_t key_length = opening_tag_end - (char*)after_separator.data;
         char *key = arena_alloc(arena, key_length + 1);
-    substr_clone(current_text, key, relative_key_start, key_length);
+        substr_clone((char*)after_separator.data, key, key_start, key_length);
+        key[key_length] = '\0';
 
-    int element_name_length = (opening_tag_end - current_text) - element_name_start;
+        // Create pattern for closing tag
-    assert(element_name_length > 0);
+        char *close_tag_pattern = arena_alloc(arena, start_slice.len + key_length + 3); // +3 for "{{" and "}}"
+        snprintf(close_tag_pattern, start_slice.len + key_length + 3, 
+                "{{%s%s}}", prefix_end, key);
 
-    char *element_name = arena_alloc(arena, element_name_length + 1);
+        // Find closing tag
-    substr_clone(current_text, element_name, element_name_start, element_name_length);
+        size_t after_opening_end = (opening_tag_end - (char*)after_separator.data) + 2;
+        Slice after_opening_slice = slice_subslice(after_separator, after_opening_end, 
+                                                 after_separator.len - after_opening_end);
         
-    int close_tag_patern_length = start_pattern_length + key_length + end_pattern_length;
+        // Find the exact closing tag by checking for complete tag pattern
-    char *close_tag_patern = arena_alloc(arena, close_tag_patern_length + 1);
+        char *close_tag = NULL;
-    snprintf(close_tag_patern, sizeof(*close_tag_patern), "%s%s%s", start_pattern, key, end_pattern);
+        char *search_start = (char*)after_opening_slice.data;
+        while ((search_start = strstr(search_start, "{{")) != NULL) {
+            if (strncmp(search_start, close_tag_pattern, strlen(close_tag_pattern)) == 0) {
+                close_tag = search_start;
+                break;
+            }
+            search_start += 2; // Move past the "{{" we found
+        }
         
-    char *close_tag = strstr(opening_tag_end + offset + 1, close_tag_patern);
         if (!close_tag) {
             raise_exception("Malformed template: missing loop end for key %s", key);
             exit(1);
         }
 
+        // Get array from context
         Json *arr = eval_object(arena, context, key);
 
         if (arr && arr->type == JSON_ARRAY) {
+            // Count array elements
             size_t elem_count = 0;
             for (Json *e = arr->child; e; e = e->next) elem_count++;
             
+            // Allocate memory for replacement
             char *replacement = arena_alloc(arena, MEM_KiB * elem_count);
-        size_t offset = 0;
+            size_t replacement_offset = 0;
 
-        char *block_buff = arena_alloc(arena, MEM_KiB);
+            // Extract template block
-	size_t relative_block_start = (size_t)opening_tag_end + 2 - (size_t)current_text;
+            size_t block_start = after_opening_end;
-	raise_trace("relative_block_start: %p = %p - 2 - %p", opening_tag_end, current_text);
+            size_t block_length = (close_tag - (char*)after_opening_slice.data);
-	size_t block_len = (size_t)opening_tag_end - (size_t)close_tag - 2;
+            char *block_buff = arena_alloc(arena, block_length + 1);
-	raise_trace("block_len %p = %p - %p - 2", block_len, opening_tag_end, close_tag);
+            substr_clone((char*)after_opening_slice.data, block_buff, block_start, block_length);
-	assert(block_len > 0);
+            block_buff[block_length] = '\0';
-        substr_clone(current_text, block_buff, relative_block_start, block_len);
 
+            // Process each array element
             for (Json *elem = arr->child; elem; elem = elem->next) {
                 char *block = arena_strdup(arena, block_buff);
                 
@@ -224,20 +186,26 @@ void hmpl_render_section_tags(Arena *arena, char **text_ptr, Json *context, cons
                 raise_trace("block after: %s", block);
                 
                 size_t block_len = strlen(block);
-            memcpy(replacement + offset, block, block_len);
+                memcpy(replacement + replacement_offset, block, block_len);
-            offset += block_len;
+                replacement_offset += block_len;
             }
 
-        replacement[offset] = '\0';
+            replacement[replacement_offset] = '\0';
             raise_trace("replacement: %s", replacement);
 
-        char *new_text = arena_repstr(arena, current_text,
+            // Calculate replacement positions
-          (size_t)opening_tag_start - 1,
+            size_t replace_start = start_index;
-          close_tag + close_tag_patern_length - opening_tag_start + 2,
+            size_t replace_length = (close_tag - (char*)after_opening_slice.data) + 
-          replacement);
+                                  start_slice.len + key_length + 2;
 
+            // Perform replacement
+            char *new_text = arena_repstr(arena, (char*)text_slice.data, replace_start, replace_length, replacement);
             *text_ptr = new_text;
+            
+            // Update text slice
+            text_slice = slice_create(char, new_text, strlen(new_text), 0, strlen(new_text));
         }
+        
         offset = start_index;
     }
 }

package/c/hmpl/make.sh

@@ -2,6 +2,8 @@
 # Usage: make.sh [build|check] [--norun] [--debug] [--color]
 # Options:
 #   build         Build the library and app (default if no mode is provided).
+#   watch         Build the library and app and watch for changes.
+#   run           Build and run the app.
 #   check         Build tests; runs them unless --norun is specified.
 #   --norun       (check only) Build tests but do not run them.
 #   --debug       Build with -O0 (debug mode).
@@ -9,7 +11,7 @@
 #   help, --help  Show this help message.
 
 check_dependencies() {
-  for dep in cc ar; do
+  for dep in cc ar entr pager; do
     if ! command -v "$dep" >/dev/null 2>&1; then
       echo "Error: Required dependency '$dep' not found." >&2
       exit 1
@@ -22,6 +24,8 @@ print_help() {
   cat <<EOF
 Usage: $0 [build|check] [--norun] [--debug] [--color]
   build         Build the library and app (default).
+  watch         Build the library and app and watch for changes.
+  run           Build and run the app.
   check         Build tests; runs them unless --norun is specified.
   --norun       (check only) Build tests but do not run them.
   --debug       Build with debug flags (-O0).
@@ -74,8 +78,7 @@ if [ -n "$COLOR_FLAG" ]; then
   CFLAGS="$CFLAGS $COLOR_FLAG"
 fi
 
-case "$MODE" in
+build() {
-  build)
   mkdir -p target
   echo "# Build library"
   # shellcheck disable=SC2086
@@ -85,10 +88,20 @@ case "$MODE" in
   echo "# Build app"
   # shellcheck disable=SC2086
   cc $CFLAGS $OPTFLAGS main.c -Ltarget -lhmpl $LDFLAGS -o target/hmpl
+}
+
+case "$MODE" in
+  watch)
+    entr -r sh ./make.sh build | pager
+    ;;
+  build)
+    build
+    ;;
+  run)
+    build && ./target/hmpl
     ;;
   check)
     mkdir -p target/test
-    export LOG_LEVEL=TRACE
     for test_file in test/*.c; do
       exe="target/test/$(basename "${test_file%.c}")"
       # shellcheck disable=SC2086

package/c/hmpl/test/test.c

@@ -101,7 +101,7 @@
   "}"
 
 #define TEST_DATA_SIMPLE_SECTION_ITERATION_TEMPLATE \
-  "{{#array element}}"                              \
+  "{{#element array}}"                              \
   "  {{element.field.subfield}}"                    \
   "{{/array}}"
 
@@ -110,78 +110,130 @@
   "value2"                                        \
   "value3"
 
+#define TEST_DATA_COMPLEX_SECTION_ITERATION_CONTEXT \
+  "{"                                               \
+  "  \"users\": ["                                  \
+  "    { \"name\": \"John\", \"age\": 30 },"       \
+  "    { \"name\": \"Jane\", \"age\": 25 }"        \
+  "  ]"                                             \
+  "}"
+
+#define TEST_DATA_COMPLEX_SECTION_ITERATION_TEMPLATE \
+  "{{#user users}}"                                \
+  "  Name: {{user.name}}, Age: {{user.age}}\n"     \
+  "{{/users}}"
+
+#define TEST_DATA_COMPLEX_SECTION_ITERATION_RESULT \
+  "  Name: John, Age: 30\n"                       \
+  "  Name: Jane, Age: 25\n"
+
 void test_eval_single_level_key(Arena *arena) {
+    raise_notice("Testing single level key evaluation");
     const char *context_text = arena_strdup(arena, "{\"name\": \"world\"}");
     Json *context = json_parse(arena, &context_text);
     if (!context) { raise_exception("Malformed json"); exit(1); }
 
     char *result = eval_string(arena, context, "name");
-    raise_debug("eval result: %s", result);
+    raise_notice("Context: %s", json_to_string(arena, context));
+    raise_notice("Query: name");
+    raise_notice("Result: %s", result);
     assert(result && strcmp(result, "world") == 0);
 }
 
 void test_eval_nested_key(Arena *arena) {
+    raise_notice("Testing nested key evaluation");
     const char *context_text = arena_strdup(arena, "{\"person\": {\"name\": \"Alice\"}}");
     Json *context = json_parse(arena, &context_text);
     if (!context) { raise_exception("Malformed json"); exit(1); }
 
     char *result = eval_string(arena, context, "person.name");
-    raise_notice("context: %s, eval result: %s", json_to_string(arena, context), result);
+    raise_notice("Context: %s", json_to_string(arena, context));
+    raise_notice("Query: person.name");
+    raise_notice("Result: %s", result);
     assert(result && strcmp(result, "Alice") == 0);
 }
 
 void test_render_interpolation_tags(Arena *arena) {
-    raise_trace("test_render_interpolation_tags(arena)");
+    raise_notice("Testing interpolation tags without prefix");
     const char *context_text = arena_strdup(arena, TEST_DATA_INTERPOLATION_CONTEXT);
     Json *context = json_parse(arena, &context_text);
     if (!context) { raise_exception("Malformed json"); exit(1); }
 
     char *text = arena_strdup(arena, TEST_DATA_INTERPOLATION_TEMPLATE); 
+    raise_notice("Template:\n%s", text);
+    raise_notice("Context: %s", json_to_string(arena, context));
 
     hmpl_render_interpolation_tags(arena, &text, context, "");
-    raise_trace("text: %s", text);
+    raise_notice("Result:\n%s", text);
     assert(strcmp(text, TEST_DATA_INTERPOLATION_RESULT) == 0);
 }
 
 void test_render_interpolation_tags_with_prefix(Arena *arena) {
+    raise_notice("Testing interpolation tags with prefix");
     const char *context_text = arena_strdup(arena, TEST_DATA_INTERPOLATION_WITH_PREFIX_CONTEXT);
     Json *context = json_parse(arena, &context_text);
     if (!context) { raise_exception("Malformed json"); exit(1); }
 
     char *text = arena_strdup(arena, TEST_DATA_INTERPOLATION_WITH_PREFIX_TEMPLATE); 
+    raise_notice("Template:\n%s", text);
+    raise_notice("Context: %s", json_to_string(arena, context));
 
     hmpl_render_interpolation_tags(arena, &text, context, ".");
+    raise_notice("Result:\n%s", text);
     assert(strcmp(text, TEST_DATA_INTERPOLATION_WITH_PREFIX_RESULT) == 0);
 }
 
 void test_render_section_tags(Arena *arena) {
+    raise_notice("Testing simple section tags");
     const char *context_text = arena_strdup(arena, TEST_DATA_SIMPLE_SECTION_ITERATION_CONTEXT);
     Json *context = json_parse(arena, &context_text);
     if (!context) { raise_exception("Malformed json"); exit(1); }
 
     char *text = arena_strdup(arena, TEST_DATA_SIMPLE_SECTION_ITERATION_TEMPLATE); 
+    raise_notice("Template:\n%s", text);
+    raise_notice("Context: %s", json_to_string(arena, context));
 
     hmpl_render_section_tags(arena, &text, context, "#", "/", " ");
+    raise_notice("Result:\n%s", text);
     assert(strcmp(text, TEST_DATA_SIMPLE_SECTION_ITERATION_RESULT) == 0);
 }
 
+void test_render_complex_section_tags(Arena *arena) {
+    raise_notice("Testing complex section tags");
+    const char *context_text = arena_strdup(arena, TEST_DATA_COMPLEX_SECTION_ITERATION_CONTEXT);
+    Json *context = json_parse(arena, &context_text);
+    if (!context) { raise_exception("Malformed json"); exit(1); }
+
+    char *text = arena_strdup(arena, TEST_DATA_COMPLEX_SECTION_ITERATION_TEMPLATE); 
+    raise_notice("Template:\n%s", text);
+    raise_notice("Context: %s", json_to_string(arena, context));
+
+    hmpl_render_section_tags(arena, &text, context, "#", "/", " ");
+    raise_notice("Result:\n%s", text);
+    assert(strcmp(text, TEST_DATA_COMPLEX_SECTION_ITERATION_RESULT) == 0);
+}
+
 int main(void) {
     init_logger();
+    raise_notice("Starting HMPL tests");
     Arena arena = arena_init(MEM_MiB * 3);
 
     // evaluation
+    raise_notice("=== Testing key evaluation ===");
     test_eval_single_level_key(&arena);
     test_eval_nested_key(&arena);
 
     // interpolation tags
+    raise_notice("=== Testing interpolation tags ===");
     test_render_interpolation_tags(&arena);
     test_render_interpolation_tags_with_prefix(&arena);
 
     // section tags
+    raise_notice("=== Testing section tags ===");
     test_render_section_tags(&arena);
+    test_render_complex_section_tags(&arena);
 
-    printf("All tests passed.\n");
+    raise_notice("All tests passed successfully");
-
     arena_free(&arena);
     return 0;
 }

package/c/watch/default.nix

@@ -1,10 +1,10 @@
-{ stdenv, gcc, lib, hectic, bash }:
+{ stdenv, gcc, lib, bash, gdb }:
 
 stdenv.mkDerivation {
   pname = "watch";
   version = "1.0";
   src = ./.;
-  doCheck = true;
+  doCheck = false;
 
   nativeBuildInputs = [ gcc gdb ];
 
@@ -17,10 +17,8 @@ stdenv.mkDerivation {
   '';
 
   installPhase = ''
-    mkdir -p $out/bin $out/lib $out/include
+    mkdir -p $out/bin
-    cp target/hmpl $out/bin/hmpl
+    cp target/watch $out/bin/watch
-    cp target/libhmpl.a $out/lib/
-    cp hmpl.h $out/include/hmpl.h
   '';
 
   meta = {

package/c/watch/main.c

@@ -9,6 +9,8 @@
 #include <fnmatch.h>
 #include <getopt.h>
 #include <ctype.h>
+#include <fcntl.h>
+#include <signal.h>
 
 #ifndef PATH_MAX
 #define PATH_MAX 4096
@@ -19,15 +21,27 @@
 #define MAX_PATTERNS 32
 #define POLL_INTERVAL_MS 100
 
+// Global flag to indicate if we're running in pager mode
+int pager_mode = 0;
+FILE *output_stream = NULL;
+int running = 1;
+
+void signal_handler(int sig) {
+    (void)sig; // Mark parameter as used to avoid warning
+    running = 0;
+}
+
 void print_usage(const char *prog_name) {
     fprintf(stderr, "Usage: %s <command> [-p <pattern1>] [-p <pattern2>] ... <dir1> [dir2] ...\n", prog_name);
     fprintf(stderr, "   or: find . -type d | %s <command> [-p <pattern1>] [-p <pattern2>] ...\n", prog_name);
     fprintf(stderr, "Options:\n");
     fprintf(stderr, "  -p <pattern>    File pattern to watch (can be used multiple times)\n");
+    fprintf(stderr, "  -P              Enable pager-friendly output (refresh mode)\n");
     fprintf(stderr, "  -h              Show this help message\n");
     fprintf(stderr, "Examples:\n");
     fprintf(stderr, "  %s 'make' -p '*.c' -p '*.h' ./src\n", prog_name);
     fprintf(stderr, "  find . -type d | %s 'echo changed' -p '*.py'\n", prog_name);
+    fprintf(stderr, "  %s -P 'make' -p '*.c' -p '*.h' ./src | less\n", prog_name);
     exit(EXIT_FAILURE);
 }
 
@@ -148,6 +162,10 @@ int match_any_pattern(const char *filename, char **patterns, int num_patterns) {
 }
 
 int main(int argc, char *argv[]) {
+    // Register signal handlers
+    signal(SIGINT, signal_handler);
+    signal(SIGTERM, signal_handler);
+
     if (argc < 2) {
         print_usage(argv[0]);
     }
@@ -159,7 +177,7 @@ int main(int argc, char *argv[]) {
     optind = 2;
     int opt;
     
-    while ((opt = getopt(argc, argv, "p:h")) != -1) {
+    while ((opt = getopt(argc, argv, "p:Ph")) != -1) {
         switch (opt) {
             case 'p':
                 if (num_patterns < MAX_PATTERNS) {
@@ -169,6 +187,9 @@ int main(int argc, char *argv[]) {
                     exit(EXIT_FAILURE);
                 }
                 break;
+            case 'P':
+                pager_mode = 1;
+                break;
             case 'h':
                 print_usage(argv[0]);
                 break;
@@ -183,6 +204,15 @@ int main(int argc, char *argv[]) {
         print_usage(argv[0]);
     }
     
+    // Set output stream - stderr for normal mode, stdout for pager mode
+    output_stream = pager_mode ? stdout : stderr;
+    
+    // Check if stdout is being piped and we're not in pager mode
+    if (!pager_mode && !isatty(STDOUT_FILENO)) {
+        pager_mode = 1;
+        output_stream = stdout;
+    }
+
     struct dir_info dirs[MAX_DIRS];
     int num_dirs = 0;
     struct file_hash files;
@@ -242,13 +272,13 @@ int main(int argc, char *argv[]) {
     }
 
     // Print the directories and patterns we're watching
-    fprintf(stderr, "Watching %d directories for files matching: ", num_dirs);
+    fprintf(output_stream, "Watching %d directories for files matching: ", num_dirs);
     for (int i = 0; i < num_patterns; i++) {
-        fprintf(stderr, "'%s'%s", patterns[i], (i < num_patterns - 1) ? ", " : "\n");
+        fprintf(output_stream, "'%s'%s", patterns[i], (i < num_patterns - 1) ? ", " : "\n");
     }
     
     for (int i = 0; i < num_dirs; i++) {
-        fprintf(stderr, "  %s\n", dirs[i].path);
+        fprintf(output_stream, "  %s\n", dirs[i].path);
     }
     
     for (int i = 0; i < num_dirs; i++) {
@@ -281,8 +311,9 @@ int main(int argc, char *argv[]) {
         closedir(dir);
     }
     
-    fprintf(stderr, "Initially found %d matching files\n", files.count);
+    fprintf(output_stream, "Initially found %d matching files\n", files.count);
-    fprintf(stderr, "Waiting for file modifications...\n");
+    fprintf(output_stream, "Waiting for file modifications...\n");
+    fflush(output_stream);
 
     struct timeval tv;
     tv.tv_sec = 0;
@@ -302,7 +333,8 @@ int main(int argc, char *argv[]) {
     
     int first_scan = 1;
     
-    while (1) {
+    // Main watch loop
+    while (running) {
         select(0, NULL, NULL, NULL, &tv);
         
         int any_changes = 0;
@@ -337,14 +369,14 @@ int main(int argc, char *argv[]) {
                         existing->exists = 1;
                         if (existing->mtime != st.st_mtime) {
                             if (!first_scan) {
-                                fprintf(stderr, "File modified: %s\n", filepath);
+                                fprintf(output_stream, "File modified: %s\n", filepath);
                                 any_changes = 1;
                             }
                             existing->mtime = st.st_mtime;
                         }
                     } else {
                         if (!first_scan) {
-                            fprintf(stderr, "New file: %s\n", filepath);
+                            fprintf(output_stream, "New file: %s\n", filepath);
                             any_changes = 1;
                         }
                         struct file_info *file = malloc(sizeof(struct file_info));
@@ -361,7 +393,7 @@ int main(int argc, char *argv[]) {
         for (int i = 0; i < files.size; i++) {
             if (files.items[i] != NULL && files.items[i]->exists == 0) {
                 if (!first_scan) {
-                    fprintf(stderr, "File deleted: %s\n", files.items[i]->path);
+                    fprintf(output_stream, "File deleted: %s\n", files.items[i]->path);
                     any_changes = 1;
                 }
             }
@@ -369,8 +401,42 @@ int main(int argc, char *argv[]) {
         
         hash_remove_nonexistent(&files);
         
+        // If in pager mode and any changes occur, clear screen and reprint status
+        if (pager_mode && any_changes) {
+            // Use ANSI escape codes to clear screen
+            fprintf(output_stream, "\033[2J\033[H");
+            
+            // Reprint header
+            fprintf(output_stream, "Watching %d directories for files matching: ", num_dirs);
+            for (int i = 0; i < num_patterns; i++) {
+                fprintf(output_stream, "'%s'%s", patterns[i], (i < num_patterns - 1) ? ", " : "\n");
+            }
+            
+            // List current files
+            fprintf(output_stream, "Currently watching %d files:\n", files.count);
+            int file_count = 0;
+            for (int i = 0; i < files.size && file_count < files.count; i++) {
+                if (files.items[i] != NULL) {
+                    fprintf(output_stream, "  %s\n", files.items[i]->path);
+                    file_count++;
+                }
+            }
+            
+            // Show last action
+            time_t current_time = time(NULL);
+            fprintf(output_stream, "\nLast event: Command executed at %s", ctime(&current_time));
+            fprintf(output_stream, "Command: %s\n", command);
+            
+            // Make sure output is flushed to the pager
+            fflush(output_stream);
+        } else if (any_changes) {
+            // In normal mode, just show status messages
+            fprintf(output_stream, "Executing command: %s\n", command);
+            fflush(output_stream);
+        }
+        
+        // Execute command if changes detected
         if (any_changes) {
-            fprintf(stderr, "Executing command: %s\n", command);
             int res = system(command);
             if (res != 0) {
                 perror("system");
@@ -393,5 +459,6 @@ int main(int argc, char *argv[]) {
     free(patterns);
     hash_free(&files);
     
+    fprintf(output_stream, "Watch terminated.\n");
     return 0;
 }

package/nvim-pager.nix

@@ -2,7 +2,7 @@
 pkgs.writeShellScriptBin "pager" ''
   nvim -R --clean -c 'set buftype=nofile' -c 'nnoremap q :q!<CR>' -c 'set nowrap' \
       -c 'set runtimepath^=${pkgs.vimPlugins.vim-plugin-AnsiEsc}' \
-      -c 'runtime! plugin/*.vim' -c 'AnsiEsc' -
+      -c 'runtime! plugin/*.vim' -c 'AnsiEsc' - $@
   #                  ^^^^^^^^^^^^^^^^^^^^
   #                  Prevents Neovim from treating the buffer as a file
   #                                          ^^^^^^^^^^^^^^^^^^^^