feat: implement history mode and AI development logging

- add dedicated history mode UI (toggle with `h`)
- allow navigation inside history with arrows
- allow selecting history entries with Enter
- add tests for history mode behavior
- introduce AI development logs (`ai-worklog.md`, `ai-prompts.md`)
- add AI worklog policy to `instructions-agent.md`

src/app/ui.py

@@ -22,6 +22,14 @@ class RenderLine:
     is_selected: bool
 
 
+@dataclass(frozen=True, slots=True)
+class HistoryLine:
+    """A rendered history row ready for terminal output."""
+
+    text: str
+    is_selected: bool
+
+
 def move_selection(current_index: int, step: int, entry_count: int) -> int:
     """Move the selected index within the available entry range."""
 
@@ -57,11 +65,23 @@ def build_render_lines(navigator: Navigator) -> list[RenderLine]:
     ]
 
 
+def build_history_lines(
+    entries: tuple[Path, ...], selected_index: int
+) -> list[HistoryLine]:
+    """Build all visible lines for history mode."""
+
+    return [
+        HistoryLine(text=str(path), is_selected=index == selected_index)
+        for index, path in enumerate(entries)
+    ]
+
+
 class TerminalUI:
     """Minimal curses UI for the directory navigator MVP."""
 
     def __init__(self) -> None:
-        self._show_history_debug = False
+        self._history_mode = False
+        self._history_selected_index = 0
 
     def run(self, navigator: Navigator) -> Path:
         """Start the interactive session and return the final directory path."""
@@ -81,6 +101,14 @@ class TerminalUI:
             if key == ESCAPE_KEY:
                 return navigator.current_path
 
+            if key == ord("h"):
+                self._toggle_history_mode(navigator)
+                continue
+
+            if self._history_mode:
+                self._handle_history_key(key, navigator)
+                continue
+
             if key == curses.KEY_UP:
                 navigator.set_selected_index(
                     move_selection(
@@ -117,10 +145,6 @@ class TerminalUI:
                 navigator.go_forward()
                 continue
 
-            if key == ord("h"):
-                self._show_history_debug = not self._show_history_debug
-                continue
-
             if key in (curses.KEY_ENTER, 10, 13):
                 navigator.enter_selected_directory()
 
@@ -128,6 +152,11 @@ class TerminalUI:
         stdscr.erase()
         height, width = stdscr.getmaxyx()
 
+        if self._history_mode:
+            self._render_history_mode(stdscr, navigator, width=width, height=height)
+            stdscr.refresh()
+            return
+
         path_text = str(navigator.current_path)
         stdscr.addnstr(0, 0, path_text, width - 1)
 
@@ -138,25 +167,62 @@ class TerminalUI:
             attributes = curses.A_REVERSE if line.is_selected else curses.A_NORMAL
             stdscr.addnstr(row, 0, line.text, width - 1, attributes)
 
-        if self._show_history_debug:
-            self._render_history_debug(stdscr, navigator, width=width, height=height)
-
         stdscr.refresh()
 
-    def _render_history_debug(
+    def _render_history_mode(
         self, stdscr: curses.window, navigator: Navigator, width: int, height: int
     ) -> None:
-        history_entries = navigator.history.entries()
+        history_lines = build_history_lines(
+            navigator.history.entries(), self._history_selected_index
+        )
         start_row = 1
 
         stdscr.addnstr(start_row, 0, "History:", width - 1, curses.A_BOLD)
 
-        for index, path in enumerate(history_entries, start=1):
+        for index, line in enumerate(history_lines, start=1):
             row = start_row + index
             if row >= height:
                 break
 
-            stdscr.addnstr(row, 0, str(path), width - 1)
+            attributes = curses.A_REVERSE if line.is_selected else curses.A_NORMAL
+            stdscr.addnstr(row, 0, line.text, width - 1, attributes)
+
+    def _toggle_history_mode(self, navigator: Navigator) -> None:
+        self._history_mode = not self._history_mode
+        if self._history_mode:
+            self._history_selected_index = self._get_current_history_index(navigator)
+
+    def _handle_history_key(self, key: int, navigator: Navigator) -> None:
+        history_entries = navigator.history.entries()
+
+        if key == curses.KEY_UP:
+            self._history_selected_index = move_selection(
+                self._history_selected_index,
+                step=-1,
+                entry_count=len(history_entries),
+            )
+            return
+
+        if key == curses.KEY_DOWN:
+            self._history_selected_index = move_selection(
+                self._history_selected_index,
+                step=1,
+                entry_count=len(history_entries),
+            )
+            return
+
+        if key in (curses.KEY_ENTER, 10, 13) and history_entries:
+            navigator.select_history_entry(self._history_selected_index)
+            self._history_mode = False
+
+    def _get_current_history_index(self, navigator: Navigator) -> int:
+        history_entries = navigator.history.entries()
+
+        for index in range(len(history_entries) - 1, -1, -1):
+            if history_entries[index] == navigator.current_path:
+                return index
+
+        return 0
 
 
 @contextmanager