A sidebar on Ctrl+B: drill's first plugin, clickable to the last gesture

.gitignore

@@ -12,3 +12,6 @@ __pycache__/
 
 # headless test harness scratch
 tests/work/
+
+# pinned third-party checkouts for the sidebar -- vendor.sh recreates them
+vendor/

KEYS.md

@@ -20,6 +20,7 @@ Syntax highlighting only. No completion, no LSP, no snippets, no AI.
 | `Ctrl+Shift+Z` | redo (needs a terminal that speaks CSI-u) | normal, insert, visual |
 | `Tab` | indent the selected lines | **selection only** |
 | `Shift+Tab` | unindent the selected lines — or, in insert, the line you are on | selection, insert |
+| `Ctrl+B` | **show / hide the file sidebar** (see its own section below) | normal, insert |
 | `Ctrl+Q` | visual block (was `Ctrl+V`) | normal, visual |
 | `Ctrl+Shift+Q` | **quit, with a confirmation** | normal, insert, **and inside the REPL** — except on a terminal with no CSI-u, where **normal mode is not covered**; see below |
 | **Shift+arrows** | **select, like any other editor** | normal, insert |
@@ -242,6 +243,32 @@ Costs: `Ctrl+R` was normal-mode redo (use `Ctrl+Y`), `Ctrl+E` was scroll-down.
 To scroll back through output, `Ctrl+\` `Ctrl+N` first — otherwise the wheel
 goes to python.
 
+## The file sidebar
+
+`Ctrl+B` shows and hides it (`Cmd+B` too on a forwarding terminal — including
+from inside the REPL, where `Ctrl+B` is deliberately left to readline). It
+opens without stealing your caret: the tree appears on the left and you are
+still typing in your code — **rooted at the folder of the file you are in**,
+not at whatever directory your shell was sitting in. The mouse is how you
+use it:
+
+| Gesture | Does |
+|---|---|
+| click a file | open it — in the file window, never the interpreter |
+| click a folder | fold / unfold |
+| `[+ File]` / `[+ Folder]` | clickable buttons in the tree's top bar; type the name at the prompt |
+| right-click | menu: new file/folder, open, open in split, rename, cut, copy, paste, delete |
+| Ctrl+click | select several (marked with `*`) |
+| drag onto a folder | **move it there** — drag a marked row and the whole selection moves |
+
+A drag released back on its own row is treated as a click that jittered, not
+a move — same trackpad rule as everywhere else in drill. `Ctrl+B` is *not*
+bound at the `/` prompt (there it stays cursor-to-start) or in the REPL
+(readline's backward-char; tmux users keep their prefix too) — that is what
+`Cmd+B` is for. The sidebar is drill's one plugin-powered feature; it loads
+on first press and never before, and `Ctrl+S`/`Ctrl+E`/`Ctrl+R` pressed in
+the tree do nothing, exactly as in the directory listing below.
+
 ## The directory listing
 
 `d` / `dt` / `ds` with no argument opens the listing instead of a file. It is

README.md

@@ -84,7 +84,11 @@ And underneath it is still real Neovim: `hjkl`, `dd`, `ciw`, macros and
 
 ## Fast enough to keep a thought
 
-Two files. No plugins, no plugin manager, no LSP, no startup spinner. From any
+No plugin manager, no LSP, no startup spinner. One deliberate exception to
+"no plugins": the optional `Ctrl+B` file sidebar is three checkouts pinned to
+exact commits, fetched once by `vendor.sh`, and **loaded only the first time
+you press the key** — never toggle it and nothing is even added to the
+runtime path. From any
 terminal, mid-thought, you're in the editor before the thought fades — and
 everything **auto-saves** about 0.7s after you stop typing, plus instantly when
 you switch away. Quit whenever; `d two-sum` brings it all back. You never lose
@@ -93,7 +97,7 @@ work, because there is no unsaved state to lose.
 ## Nothing helps you type
 
 No autocomplete. No LSP, no Copilot, no snippets, no signature hints, no
-auto-import. Not "turned off" — **absent, at every source, and a 558-case test
+auto-import. Not "turned off" — **absent, at every source, and a 729-case test
 suite asserts it**. Syntax highlighting is the only thing on screen besides your
 own keystrokes. Your `~/.config/nvim` and `~/.vimrc` are never touched; the
 config loads with `nvim -u` and exists only inside drill.
@@ -109,6 +113,22 @@ t -k      # stop
 
 Non-blocking, with a sound and a desktop notification at zero.
 
+## `Ctrl+B` — a file sidebar, when you want one
+
+The one optional extra: press `Ctrl+B` (or `Cmd+B` on a Mac that forwards it,
+REPL included) and a file tree slides in on the left — press again and it is
+gone, with your caret still in your code either way. It is built for the
+mouse: **one click** opens a file or folds a folder, **`[+ File]` /
+`[+ Folder]` are real clickable buttons**, **right-click** gets a menu (new,
+rename, cut/copy/paste, delete, open in split), **Ctrl+click** multi-selects,
+and **dragging a file onto a folder moves it** — drag a selected one and the
+whole selection moves. Details: [docs/explorer.md](docs/explorer.md).
+
+This is drill's only plugin-powered feature, and it stays out of the way: the
+three checkouts are pinned to exact commits and load lazily on the first
+press, so an editor that never opens the sidebar runs exactly the config it
+always has.
+
 ## The quality-of-life layer
 
 - **Quit that can't misfire** — `Ctrl+Shift+Q` asks first, and Cancel is the
@@ -161,7 +181,7 @@ so `git pull` stays clean forever.
 | [KEYS.md](KEYS.md) | every keybinding, every conflict, and how each is resolved |
 | [docs/design.md](docs/design.md) | why the editor behaves the way it does — the mouse, autosave, search, quitting, and the five deliberate trade-offs |
 | [docs/verify.md](docs/verify.md) | prove nothing is helping you, and that your own nvim is untouched |
-| [docs/testing.md](docs/testing.md) | the 558-case gate that drives the real config with real keycodes |
+| [docs/testing.md](docs/testing.md) | the 729-case gate that drives the real config with real keycodes |
 | [docs/recording.md](docs/recording.md) | `demo.sh` — the self-driving tour that recorded the video above |
 | [docs/wsl.md](docs/wsl.md) | WSL: the clipboard, the timer's sound and notification, and the one thing you have to check by hand |
 

docs/explorer.md

@@ -0,0 +1,75 @@
+# The file sidebar
+
+`Ctrl+B` shows it, `Ctrl+B` hides it, and in both directions your caret stays
+in your code — the tree is furniture, not a destination. On a Mac whose
+terminal forwards Cmd ([docs/macos-cmd.md](macos-cmd.md)), `Cmd+B` does the
+same thing and also works from inside the REPL, where `Ctrl+B` is
+deliberately left alone (readline's backward-char, and tmux's prefix).
+
+**It roots at the folder of the file you are in**, freshly on every open —
+`d lld-prac main` shows the `lld-prac/` folder with `main.py` highlighted,
+no matter which directory your shell happened to be in when you typed it.
+(drill launches nvim from wherever you were; the shell's directory is a tree
+of everything *except* your project.) Switch to a file elsewhere and the next
+`Ctrl+B` roots there instead.
+
+## The gestures
+
+Everything is a mouse gesture; the keyboard is only for typing names.
+
+- **Click a file** — opens it, in the file window. Never in the interpreter:
+  the open logic refuses terminal windows outright.
+- **Click a folder** — folds or unfolds it. One click. There is no
+  double-click folklore anywhere in the tree.
+- **`[+ File]` / `[+ Folder]`** — real buttons in the tree's top bar. Click,
+  type a name at the prompt, Enter. The location is taken from the row your
+  cursor is on: a folder row means *in here*, a file row means *next to me*.
+- **Right-click** — a menu on the row you clicked: New file, New folder,
+  Open, Open in split, Rename, Cut, Copy, Paste, Delete. Plain text labels
+  on purpose — no nerd font required, anywhere in the sidebar.
+- **Ctrl+click** — select several files (marked with `*`).
+- **Drag a file onto a folder** — moves it into that folder. Drop it on a
+  file instead and it moves next to that file. If the row you dragged was
+  marked, the **whole marked selection moves** in one gesture.
+
+A press that drifts a cell before the button comes up is a click that
+jittered, not a drag — the same trackpad rule the rest of drill's mouse
+handling lives by, so nothing ever moves by accident.
+
+Inside the tree, drill's file keys say no the same way they do in the
+directory listing: `Ctrl+S`, `Ctrl+E`, `Ctrl+R` do nothing there.
+
+## What it costs when you don't use it
+
+Nothing. This is drill's one exception to "no plugins", and it is built to
+stay an exception:
+
+- The three checkouts (nvim-tree, and volt+menu for the right-click menu)
+  are **pinned to exact commits** by `vendor.sh` — a table of three SHAs and
+  a loop, not a plugin manager. The same commits on every machine, every
+  install, until a pin is bumped on purpose.
+- **Nothing loads at startup.** The checkouts are not even on the runtime
+  path until the first `Ctrl+B` of the session. Never press it and you run
+  the config drill always had, byte for byte.
+- The same change **sealed the accidental plugin door**: plugins in your
+  `~/.local/share/nvim/site` used to load inside drill through `packpath`
+  even though the README said "no plugins". They no longer do. Your own
+  nvim setup outside drill is untouched either way.
+
+## When it says no
+
+- *"sidebar plugins are not fetched"* — run `./vendor.sh` in your drill
+  directory (`~/drill` unless you moved it). `install.sh` does this for you;
+  a `git pull` upgrade does not.
+- *"the sidebar needs nvim 0.10+"* — everything else in drill still works;
+  the pinned plugins are what need 0.10.
+- `Cmd+B` does nothing — your terminal is not forwarding Cmd. One setting:
+  [docs/macos-cmd.md](macos-cmd.md).
+- **Right-click opens your terminal's own menu instead of drill's** — the
+  terminal is eating the click before nvim sees it. In iTerm2 that is a
+  Pointer binding, and it wins over mouse reporting: **Settings → Pointer →
+  Bindings**, select the *Right button · single click → Open Context Menu*
+  row, press **−** to remove it. With the binding gone, the click reaches
+  drill whenever the editor is running, and iTerm2 still shows its own menu
+  at the shell prompt, where nothing is listening for the mouse. (Ctrl-click
+  in drill is multi-select, not the menu — that one is drill's on purpose.)

docs/macos-cmd.md

@@ -42,6 +42,7 @@ So drill binds every editor chord on Cmd too, same modes, same handlers:
 | `Cmd+Z` | undo |
 | `Cmd+Shift+Z` | redo (the mac redo; `Ctrl+Y` still works everywhere) |
 | `Cmd+/` | comment / uncomment |
+| `Cmd+B` | the file sidebar — including from the REPL, where `Ctrl+B` is left to readline |
 | `Cmd+Q` | quit, with the same confirmation as `Ctrl+Shift+Q` |
 | `Cmd+←` / `Cmd+→` | start / end of line |
 | `Cmd+↑` / `Cmd+↓` | start / end of file |
@@ -56,7 +57,7 @@ like Shift+arrows and typing over that selection replaces it.
 an *unmapped* forwarded chord does not die quietly in nvim — measured, a bare
 `<D-w>` typed the literal text `<D-w>` into the buffer in insert, replaced
 the selection with it in Select mode, and ate a character in normal mode. So
-a reflexive Cmd+W or Cmd+B from a mac hand would spray key notation into
+a reflexive Cmd+W or Cmd+N from a mac hand would spray key notation into
 your file. drill floors every printable Cmd chord to a no-op — in the REPL
 too, where the junk would have gone to python — and binds the useful ones on
 top.

docs/testing.md

@@ -5,20 +5,21 @@ and diffing what comes out. Nothing is mocked: if a case passes, that keystroke
 does that thing in this config.
 
 ```sh
-./tests/run.sh            # 558 cases; exit 0 only if all pass
+./tests/run.sh            # 729 cases; exit 0 only if all pass
 ./tests/run.sh sel_       # just the select-mode cases
 ```
 
 | Suite | Cases | What it drives |
 |---|---|---|
-| `suite_options.sh` | 86 | config invariants no key-driven test can see: completion off at every source, zero LSP clients, no swap/backup/undo files, the cursor shape in both panes, and every mapping registered in the modes it claims — including that `Ctrl+/` is *not* bound in terminal mode and `Ctrl+C` is *not* bound in normal or terminal, so SIGINT still reaches a running program |
-| `suite_config.sh` | 30 | headless nvim: shift+arrow selection, `Tab`/`Shift+Tab`, cut/paste/select-all, undo/redo, `Ctrl+C` copying without losing the selection |
-| `suite_mouse.sh` | 58 | pty: click to caret from every mode, into empty space and past EOF, jitter in both axes, real drags, double-click, Option/Ctrl+click, and clicks between the file and the interpreter |
+| `suite_options.sh` | 172 | config invariants no key-driven test can see: completion off at every source, zero LSP clients, no swap/backup/undo files, no third-party site dir on `runtimepath` OR `packpath`, the cursor shape in both panes, and every mapping registered in the modes it claims — the whole Cmd layer and the sidebar toggle included, and that `Ctrl+/` is *not* bound in terminal mode and `Ctrl+C` is *not* bound in normal or terminal, so SIGINT still reaches a running program |
+| `suite_config.sh` | 52 | headless nvim: shift+arrow selection, `Tab`/`Shift+Tab`, cut/paste/select-all, undo/redo, `Ctrl+C` copying without losing the selection, and the Cmd chords with their `<Nop>` floor |
+| `suite_mouse.sh` | 66 | pty: click to caret from every mode, into empty space and past EOF, jitter in both axes, real drags, double-click, Option/Ctrl+click, clicks between the file and the interpreter, and backspacing out of the ghost space |
 | `suite_search.sh` | 36 | `Ctrl+F`, exactly when the highlight and hints appear and go, and the Esc chain — including that it resumes typing at the exact column. Headless **and** pty: the Esc chain cannot be seen headlessly, because feedkeys force-ends Insert as the typeahead drains |
 | `suite_autosave.sh` | 8 | what is on **disk**, read back from the shell |
 | `suite_quit.sh` | 21 | pty: the confirmation is drawn, Cancel and Esc both return you to typing, Quit writes the pending edit, and all of it again from inside the REPL |
 | `suite_runwin.sh` | 12 | pty: the `Ctrl+R` output window — that it closes when you leave it, that any key still closes it from inside, that `Ctrl+R` then `Ctrl+E` is two windows and not three, and that a program still running is left alone |
 | `suite_netrw.sh` | 10 | pty: the directory listing is not a file — `Ctrl+S` does not wedge it, `Ctrl+E`/`Ctrl+R` start nothing. Headless is useless here: it does not produce a netrw buffer at all |
+| `suite_tree.sh` | 55 | pty: the `Ctrl+B` sidebar, gesture by gesture — both toggle chords (Cmd+B as raw CSI-u bytes), focus that never leaves your code, single-click open and fold, the winbar `[+ File]`/`[+ Folder]` buttons all the way to files on disk, the right-click menu drawn and an item clicked by its float coordinates, ctrl-click marks, drag-and-drop single and marked-pair moves, a jitter that must not move anything, the three-window layout with the REPL, and the root landing on the file's folder on every open |
 | `suite_timer.sh` | 36 | not nvim at all — 18 assertions against `drill.sh` run under **bash and zsh**, which disagree about word splitting |
 | `suite_projects.sh` | 40 | also not nvim — nested `d <dir> <name>` and `d search` against stubbed `nvim`/`fzf` binaries in a scratch `DRILL_HOME`, under **bash and zsh** — including that `..` cannot leave the bucket and bracketed names resolve literally |
 | `suite_preload.sh` | 26 | the LeetCode desk: import-free files using the toolkit under `r`/`ri` in **bash and zsh** — shadowing, argv, `__name__`, exit codes, sibling imports in project folders, names still live at the prompt after a raise, a typo'd name getting python's own error, the plain-python3 fallback — plus a pty pass proving `Ctrl+R` and `Ctrl+E` route through the shim |

docs/verify.md

@@ -18,7 +18,10 @@ And confirm it left your own setup alone: run plain `nvim` and check
 - No autocomplete, no LSP, no Copilot, no AI, no snippet expansion
 - No linter suggestions, no auto-import, no signature hints
 - Syntax highlighting only — nothing else appears on screen while you type
-- No plugin manager, no distro
+- No plugin manager, no distro. The one exception to "no plugins" is the
+  optional `Ctrl+B` sidebar: three checkouts pinned to exact commits by
+  `vendor.sh`, loaded only when you first press the key, and none of them
+  touches what appears while you type
 - No swapfile, no backup, no undo file — the directory holds the `.py` you
   wrote and nothing else
 - Stock Python 3, Neovim and fzf — and fzf only powers `d search`, never the

docs/wsl.md

@@ -142,7 +142,7 @@ Ctrl+click are both just clicks, not vim surprises.
 ## Running the tests
 
 ```sh
-./tests/run.sh      # 558 cases
+./tests/run.sh      # 729 cases
 ```
 
 Needs a clipboard provider on PATH; `run.sh` warns up front if there is none,