doc: Remove ideas for marks and registers from plans.

docs/DESIGN.md

@@ -80,7 +80,7 @@ There are two ways to respond to them: **exec hooks** and
 | `on-select` | User confirms (Enter) | Apply the choice |
 | `on-cancel` | User cancels (Escape) | Revert preview |
 | `on-filter` | Filter text changes | Dynamic item reloading |
-| `on-mark` | User marks/unmarks an item | Visual feedback |
+| `on-toggle` | User toggles an item's selection | Visual feedback (deferred) |
 
 ### Exec Hooks (fire-and-forget)
 
@@ -383,16 +383,14 @@ designed.
 | `Ctrl+D` / `Ctrl+U` | Half-page down / up |
 | `Ctrl+F` / `Ctrl+B` | Full page down / up |
 | `/` | Enter filter (insert) mode |
-| `n` / `N` | Next / previous filter match |
-| `m{a-z}` | Set mark at current position |
-| `'{a-z}` | Jump to mark |
-| `"a` | Select into register `a` |
-| `v` | Toggle multi-select on current item |
-| `V` | Visual line select mode |
+| `Space` | Toggle select + move down (`--multi`) |
+| `V` | Enter visual line mode (`--multi`) |
+| `u` | Undo last selection change (`--multi`) |
+| `U` | Clear all selections (`--multi`) |
+| `Ctrl+R` | Redo selection change (`--multi`) |
 | `Enter` | Confirm selection |
 | `Escape` | Cancel and exit |
 | `q` | Cancel and exit |
-| `Space` | Toggle select current item and move down |
 
 `H`/`M`/`L` (viewport-relative jumps) are deferred. They're
 nice-to-have but not essential for the first pass of vim
@@ -400,12 +398,26 @@ navigation.
 
 ### Multi-Select
 
-- `Space` or `v` toggles selection on current item
-- `V` enters visual line mode, moving up/down selects ranges
-- All selected items are emitted on confirm
-- `"a` through `"z`: select into named registers (like vim
-  yanking)
-- Registers can be recalled or included in output
+Requires `--multi` flag. Without it, toggle/select actions
+are no-ops and confirm always returns a single item.
+
+- `Space` or `Tab` toggles selection on the cursor item and
+  moves down. `Shift+Tab` toggles and moves up.
+- `V` enters visual line mode: `j`/`k` extend the range,
+  `Space`/`Enter` force-selects the range and returns to
+  normal mode, `V` cancels back to normal with no change.
+- `u` undoes the last selection change, `Ctrl+R` redoes.
+  Undo/redo stacks track snapshots of the full selection set.
+- `U` clears all selections (undoable).
+- Selections survive filter changes. Toggling item "foo",
+  then filtering to something else, then confirming still
+  includes "foo" in the output.
+- `--selection-order` flag: output items in the order they
+  were selected (insertion order) instead of the default
+  input order.
+- Confirm with selections: outputs all selected items.
+  Confirm with no selections in multi mode: falls back to
+  the cursor item as a single-element result.
 
 ### Drill-Down
 
@@ -479,7 +491,7 @@ A few built-in themes ship with pikl. `--theme monokai` or
 ## Sessions
 
 `--session name` persists the menu's state (filter text,
-scroll position, selected items, marks, registers) across
+scroll position, selections) across
 invocations. State lives in
 `~/.local/state/pikl/sessions/`.
 

docs/DEVPLAN.md

@@ -170,19 +170,26 @@ through hooks and structured I/O. A handler hook can
 receive hover events and emit commands to modify menu
 state.
 
-## Phase 4: Multi-Select & Registers
+## Phase 4: Multi-Select
 
-Power selection features.
+Selection with undo/redo. No marks or registers: filtering
+already handles navigation, and selections surviving filter
+changes covers the register use case.
 
 **Deliverables:**
-- Space to toggle select, V for visual line mode
-- Multi-select output (multiple JSON lines)
-- Named registers (`"a` through `"z`)
-- Marks (`m{a-z}`, `'{a-z}`)
-- `--multi` flag to enable multi-select mode
+- `--multi` flag to gate all multi-select behaviour
+- `Space`/`Tab` toggle-select, `Shift+Tab` toggle-up
+- `V` visual line mode (force-select ranges)
+- `u`/`Ctrl+R` undo/redo selection changes, `U` clear all
+- Selections survive filter changes (tracked by original index)
+- `--selection-order` flag for insertion-order output
+- Multi-item output: one JSON line per selected item
+- Action-fd commands: toggle-select, select-all, deselect-all,
+  undo-selection, redo-selection
+- Test DSL: `multi` fixture, `selected_items` assertion
 
-**Done when:** You can select multiple items, store them
-in registers, and get them all in the output.
+**Done when:** `seq 1 20 | pikl --multi`, toggle a few items
+with Space, confirm, and all selected items appear on stdout.
 
 ## Phase 5: Table Mode & CSV
 
@@ -204,8 +211,7 @@ Persistence and external control.
 
 **Deliverables:**
 - `--session name` for state persistence
-- Session state: filter, scroll position, selections,
-  marks, registers
+- Session state: filter, scroll position, selections
 - Session history log file
 - Unix socket IPC while running
 - IPC commands: push/remove/update items, set filter,