v2: add delete fast from history via long-press BACK in edit window

Adds history_delete_entry() in fastforge_core.c which removes an entry at
a given index by shifting the tail with memmove, zeroing the vacated slot,
recomputing streaks, and persisting. Wires a long-press BACK (700ms) handler
in the history edit window that calls it. Updates the hint text to inform
the user. Fixed hint text buffer from [40] to [48] to fit the full string.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

3 files changed, 38 insertions, 2 deletions

diff --git a/src/c/fastforge.c b/src/c/fastforge.c
index 2dc7cf0..7f6c360 100644
--- a/src/c/fastforge.c
+++ b/src/c/fastforge.c
@@ -106,7 +106,8 @@ static char s_history_edit_start_text[32];
 static char s_history_edit_end_text[32];
 static char s_history_edit_duration_text[48];
 static char s_history_edit_stage_text[24];
-static char s_history_edit_hint_text[40];
+/* 45 bytes needed: "UP/DN adj SEL field\nHOLD save  BACK-hold del" + NUL */
+static char s_history_edit_hint_text[48];
 static char s_running_edit_start_text[32];
 static char s_running_edit_elapsed_text[32];
 static char s_running_edit_goal_text[32];
@@ -815,7 +816,7 @@ static void refresh_history_edit_window_content(void) {
            s_history_edit_field == EDIT_FIELD_NOTE ? '>' : ' ', note_text);
   snprintf(s_history_edit_stage_text, sizeof(s_history_edit_stage_text), "Badge %s",
            badge_label ? badge_label : "--");
-  snprintf(s_history_edit_hint_text, sizeof(s_history_edit_hint_text), "UP/DN adjust SEL field\nHOLD save");
+  snprintf(s_history_edit_hint_text, sizeof(s_history_edit_hint_text), "UP/DN adj SEL field\nHOLD save  BACK-hold del");
 
   text_layer_set_text(s_history_edit_title_layer, s_history_edit_title_text);
   text_layer_set_text(s_history_edit_start_layer, s_history_edit_start_text);
@@ -940,6 +941,19 @@ static void history_edit_back_click_handler(ClickRecognizerRef recognizer, void
   window_stack_remove(s_history_edit_window, true);
 }
 
+/* Long-press BACK deletes the current entry and returns to the history list. */
+static void history_edit_delete_click_handler(ClickRecognizerRef recognizer, void *context) {
+  (void)recognizer;
+  (void)context;
+  if (!history_delete_entry(s_history_edit_index)) {
+    return;
+  }
+  s_history_edit_index = -1;
+  refresh_timer_view();
+  refresh_stats_window_content();
+  window_stack_remove(s_history_edit_window, true);
+}
+
 static void history_edit_click_config_provider(void *context) {
   (void)context;
   window_single_click_subscribe(BUTTON_ID_UP, history_edit_up_click_handler);
@@ -947,6 +961,7 @@ static void history_edit_click_config_provider(void *context) {
   window_single_click_subscribe(BUTTON_ID_SELECT, history_edit_select_click_handler);
   window_single_click_subscribe(BUTTON_ID_BACK, history_edit_back_click_handler);
   window_long_click_subscribe(BUTTON_ID_SELECT, 500, history_edit_save_click_handler, NULL);
+  window_long_click_subscribe(BUTTON_ID_BACK, 700, history_edit_delete_click_handler, NULL);
 }
 
 static void running_fast_edit_apply_delta_minutes(int delta_minutes) {
diff --git a/src/c/fastforge.h b/src/c/fastforge.h
index 263a75b..de1959c 100644
--- a/src/c/fastforge.h
+++ b/src/c/fastforge.h
@@ -29,5 +29,6 @@ bool fast_is_running(void);
 bool fast_start(uint16_t preset_target_minutes);
 bool fast_stop(void);
 bool fast_cancel(void);
+bool history_delete_entry(int index);
 
 #endif
diff --git a/src/c/fastforge_core.c b/src/c/fastforge_core.c
index cde224f..0b4455e 100644
--- a/src/c/fastforge_core.c
+++ b/src/c/fastforge_core.c
@@ -215,6 +215,26 @@ static void append_history_entry(const FastEntry *entry) {
   history[MAX_FASTS - 1] = *entry;
 }
 
+/* Remove history[index], shift tail entries down, and persist the change. */
+bool history_delete_entry(int index) {
+  if (index < 0 || index >= history_count) {
+    return false;
+  }
+
+  int entries_after = history_count - index - 1;
+  if (entries_after > 0) {
+    memmove(&history[index], &history[index + 1], sizeof(FastEntry) * (size_t)entries_after);
+  }
+  history_count--;
+  memset(&history[history_count], 0, sizeof(FastEntry));
+
+  recompute_streak_data_for_today();
+  save_all_data();
+  history_menu_reload();
+  APP_LOG(APP_LOG_LEVEL_INFO, "Deleted history entry %d, history_count=%d", index, history_count);
+  return true;
+}
+
 static uint16_t resolve_target_minutes(uint16_t preset_target_minutes) {
   if (preset_target_minutes > 0) {
     return preset_target_minutes;