feat(directives): harvest 2 directives from docs/guide_state_lifecycle.md (undo/redo 100-snapshot, reset preserves project path)

conductor/directives/undo_redo_100_snapshot_capacity/meta.md

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+# undo_redo_100_snapshot_capacity
+
+## v1
+
+**Why this iteration:** Lifted verbatim from `docs/guide_state_lifecycle.md:56-117 (§1 Undo/Redo: HistoryManager + UISnapshot)`.
+**Source:** `docs/guide_state_lifecycle.md:56-117 (§1 Undo/Redo: HistoryManager + UISnapshot)`
+**Lifted:** 2026-07-02 (Phase A expansion harvest; user directive 2026-07-02)

conductor/directives/undo_redo_100_snapshot_capacity/v1.md

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+## HistoryManager — the 100-snapshot undo/redo stack
+
+`src/history.py:71 HistoryManager` is a 100-snapshot capacity stack with the following API:
+
+- `push(state, description)` — appends; clears the redo stack; pops the oldest if capacity exceeded.
+- `undo(current_state, current_description)` — moves current state to redo stack; returns the top of the undo stack.
+- `redo(...)` — inverse of undo.
+- `jump_to_undo(index, current_state, current_description)` — time-travels to any past snapshot, moving subsequent states to the redo stack.
+- `can_undo`, `can_redo` properties
+- `get_history()` — returns `[{description, timestamp}, ...]` for the History List view
+
+The `max_capacity=100` is the default and is sufficient for a 5-second window of rapid typing or a longer session of infrequent edits.
+
+## The Push Trigger — debounced change detection at render frame
+
+The undo stack is **not** pushed on every keystroke. It's pushed via debounced change-detection at the start of every render frame:
+
+```python
+current = self._take_snapshot()
+if self._last_ui_snapshot is None:
+ self._last_ui_snapshot = current
+ return
+
+changed = (
+ current.ai_input != self._last_ui_snapshot.ai_input or
+ ...
+ len(current.disc_entries) != len(self._last_ui_snapshot.disc_entries) or
+ ...
+)
+
+if changed:
+ self.history.push(current, description="<auto>")
+ self._last_ui_snapshot = current
+```
+
+The check is at the start of every render frame. `copy.deepcopy(self.disc_entries)` is the most expensive part — O(N) where N is the entry count. The full snapshot push only happens when a change is detected.