ELYTerminal/AGENTS.md

# AGENTS.md

ELYTerminal. A terminal on GPUI and Ely components. `PRD.md` says what it does; `TASKS.md` says how far it is.

## Stack

- Rust 1.95, edition 2024. One binary crate, `elyterminal`.
- Ely (`ely-gpui-component`) from git.zacharyzhang.com, pinned by rev. gpui and gpui_platform from crates.io's `gpui-pre`, the exact version Ely pins, under their crate names through `package`.
- `alacritty_terminal` 0.26: grid, parser, pseudo-terminal, event loop.
- `serde`, `serde_json`: settings. `dirs`: the config folder. `log`, `env_logger`: logs to stderr. `unicode-normalization`, on macOS: Git's marks in composed form.
- On Linux, `wayland-client`, `wayland-backend` and `wayland-protocols` (staging) ask the compositor for `ext_background_effect_v1` on gpui's own connection; `wayland-server` hosts a compositor in the tests. `x11rb` sets `_KDE_NET_WM_BLUR_BEHIND_REGION`; its test runs Xvfb.

## Commands

- `cargo run` opens the app. `RUST_LOG=elyterminal=debug cargo run` logs more; `trace` logs each paint.
- `cargo run --example shot -- [--keys "SPECS"] <png> <program> [args…]` runs a program in the main window, plays SPECS on it, and writes a PNG of the window (macOS; no permission needed for the app's own window), naming the AppKit views under its content: gpui's blur is a `BlurredView`, and a capture of one window shows its alpha, not the blur behind it; it logs the menu bar, each item with its key. It shows its window without activating the app, so gpui keeps drawing it and keystrokes or clicks meant for other apps stay there. Run it with `HOME` pointing at a temp folder to try settings without touching your own. SPECS, space-separated:
  - keys as real AppKit events: `a`, `ctrl-c`, `lopt-f` and `ropt-f` (left and right Option), `cmd-v`, `repeat-up` (AppKit's repeat flag);
  - input method calls: `mark:é` composes, `commit:é` types;
  - `activate` and `deactivate` the app, which takes real keystrokes while active: keep the two specs adjacent. macOS may delay or refuse the activation; each `shot: typed` line says whether the app was active;
  - `to:settings` and `to:main` aim the specs after them, and the picture, at that window, which becomes the app's key window, since AppKit sends keys there; the app stays inactive, and gpui sends an inactive window no focus or blur events, so press Enter to commit a field. AppKit gives an inactive app's key that a menu item holds to the menu, and gpui sends the item's action to the main window, which an inactive app lacks: only an app-wide action runs, such as Quit, Settings or the font's size;
  - mouse gestures handed to gpui's view, at points from the content's top-left, modifiers as for keys: `click@x,y`, `click2@`, `click3@`, `rclick@`, `mclick@`, `drag@x,y@x,y`, `move@x,y`, the steps `ldown@`, `lup@`, `ldrag@`, `rdown@`, `rup@`, `mdown@`, `mup@`, and `scrollup@x,y@lines`, `scrolldown@x,y@lines`.
- `scripts/check.sh`: fmt, clippy `-D warnings`, tests, the 500-line rule.
- `scripts/linux.sh ARGS` runs `cargo ARGS` on the working tree in a Linux container, the build kept in Docker volumes; `scripts/linux.sh test --locked` runs the tests as a user, not root, as CI does. The tree goes in as a tar stream, every file dated now: Colima's shared folder can show the VM a file as it was before an edit, and cargo judges by date, so a tree older than the last build would reuse that build. It needs a Docker daemon: on macOS, Colima (`colima start`).

## Layout

- `src/main.rs`: start. `src/lib.rs`: the modules, public so tests and examples reach them. `src/app.rs`: fonts, settings, integration, then the main window. `src/menus.rs`: the menu bar, the keys of Quit, the font's size and Minimize, and what they do. `src/blur.rs`: what the window shows of the desktop, from the opacity and blur settings, set as they change; `blur/wayland` asks a Wayland compositor for blur behind the window's surface through `ext_background_effect_v1`; `blur/x11` names the window's pane in `_KDE_NET_WM_BLUR_BEHIND_REGION`. `src/workspace.rs`: the window's content, Ely's `ColumnShell` with the sessions, terminal and right columns, their toggles, the right column's Git and Files switch, the title, and the sessions' lifecycle. `src/sessions.rs`: a session and its row. `src/files.rs`: the Files panel, the shown session's folder as Ely's `Tree` with Git's marks. `src/git.rs`: git through its command line: Files' marks, and the Git panel's status, stage, unstage, discard, commit and log; `src/git/diff.rs` reads git's diff into Ely's stretches. `src/git/panel.rs`: the Git panel's state and actions; `src/git/panel/view.rs`: how it draws.
- `src/settings`: the model, its ranges, and `SettingsStore`, the global that loads, checks and saves `settings.json`; `window` is the settings window, `window/appearance` its Appearance page, `window/terminal` its Terminal page. `tests/fonts.rs` brings its own main: gpui builds its Mac platform only on the main thread.
- `src/themes`: built-in terminal themes, the chrome palette each maps to, and `apply`, which dresses the app for the system's appearance.
- `src/term`: the terminal engine. `pty` starts a program through alacritty's event loop; `tap` wraps the pty so its reader scans OSC 7 and the mouse modes before the parser. `unix` starts the program itself, so a failed `chdir` fails the start; Windows uses alacritty's ConPTY. `shell` writes the integration scripts at start and builds each shell's launch. `frame` reads the grid into styled rows, `boxes` turns box drawing, block elements and powerline arrows into rects and polygons (`boxes/outline` strokes curves and diagonals into polygons), `ink` resolves colors, `paint` draws rows, decorations and the cursor, `view` is the entity: pty events, metrics, blink, resize. `zoom` holds the points Bigger and Smaller add to the Size setting, unsaved. `keys` turns key events into bytes, the kitty protocol and, in `keys/legacy`, xterm's encoding, with no gpui types; `input` is the view's key listeners, the bindings that keep Tab and F6 from Ely's focus moves, and its IME handler; `mac` reads the Option side and repeat flag of AppKit's current event, keeps held keys repeating, and hands Command key-ups to the focused view. `mouse` encodes mouse reports, with no gpui types; `links` finds the link at a cell; `pointer` is the view's mouse listeners: selection, reports, wheel, links, copy and paste. `find` is the find box: Ely's `FindWidget`, and Ely's `find_all` over the grid's shown text.
- `assets/shell-integration`: ELYTerminal's own scripts (not Ghostty's, which are GPL): zsh through `ZDOTDIR`, bash through `--rcfile`, fish through `XDG_DATA_DIRS`, PowerShell through `-NoExit -Command`. Each prompt sends OSC 7 and, except in fish, whose `fish_title` stays, a title.
- `assets/fonts`: JetBrains Mono 2.304's bold and italic faces (OFL; Ely bundles regular), and Nerd Fonts 3.5.1's JetBrains Mono NF Mono Regular, which draws icons a font lacks.
- `assets/themes`: Ghostty theme files copied verbatim from iTerm2-Color-Schemes (MIT, its `LICENSE` beside them).

## Rules

- Hand-written files stay at or under 500 lines; `Cargo.lock`, which Cargo writes, is exempt. Comments are one short line, and rare.
- Fail fast. No silent fallbacks. An error names its owner and what failed.
- Log every state change on a key path with `log`: spawn, exit, folder change, settings load and save, blur path.
- No dead code, no versioned names, no compatibility shims.
- Colors, sizes and radii come from Ely's theme. Gaps use gpui's rem helpers.
- No credential in any file. Pushes pass the token as an `http.extraHeader` on the command line.

## Decisions

- 2026-10-14: ELYTerminal owns its terminal engine on `alacritty_terminal`. Ely's `Terminal` lacks mouse reporting, IME, kitty keys and style settings, and a library widget should not carry an app's engine.
- 2026-10-14: the working directory comes from OSC 7, read by a tap on the pty reader, sent by injected shell integration. vte drops OSC 7.
- 2026-10-14: Git through the `git` command line, not libgit2.
- 2026-10-14: license MIT, as Ely.
- 2026-10-14: on Unix the pty is ELYTerminal's own: alacritty 0.26 ignores `chdir`'s result, so a session could start in the wrong folder. Its traits feed alacritty's event loop, keyed 0 and 1 as alacritty's private constants are; alacritty is pinned to =0.26.0 for that.
- 2026-10-14: bash integration loads through `--rcfile`, not Ghostty's `--posix` and `ENV`: macOS's bash 3.2 ignores `ENV` there. bash then runs as a non-login shell; on macOS the script reads the login files itself, so `logout` and `~/.bash_logout` do not apply.
- 2026-10-14: icons fall back by hand: a private-use character the font lacks paints in JetBrains Mono NF Mono. gpui's macOS fallbacks go through CoreText's cascade list, which never sees fonts added in memory, and gpui loads no font without an `m`, so the symbols-only Nerd Font cannot load.
- 2026-10-14: box drawing (U+2500–U+257F), block elements (U+2580–U+259F) and powerline shapes (U+E0B0–U+E0B7) follow Ghostty's sprite rules (MIT, `LICENSE-GHOSTTY`): whole device pixels, line thickness the underline's, each cell clipped to itself, so lines join across cells whatever the font. A character's pieces never overlap: gpui blends every quad and every path triangle on its own, so a dim line painted twice brightens where it crosses. A drawn base keeps its geometry under combining marks, which paint over a no-break space.
- 2026-10-14: keys follow Ghostty's encoder (MIT). Keys the program reads go out from the key listener; plain text falls through to the input handler, so IME and dead keys compose. Ctrl+[, Ctrl+I and Ctrl+M go as fixterms CSI u, as in Ghostty. Keypad keys always type their characters: Ghostty keeps mode 1035 on, and gpui names keypad keys as main keys on every platform. Ely binds Tab, Shift-Tab, F6 and Shift-F6 to focus moves, and bindings run before listeners; `NoAction` bindings under the `Terminal` context hide them, so these keys reach the listeners with press, repeat and release.
- 2026-10-14: each kitty flag reshapes only what it names, as kitty's encoder does: functional keys keep legacy bytes until disambiguate, events or all is set, and text keys type until all is set. Cmd is kitty's Super, bit 8; a Cmd combo no binding takes reaches the program.
- 2026-10-14: an input method's commit goes to the program as UTF-8 under every kitty flag, as kitty (`keys.c`, `GLFW_IME_COMMIT_TEXT`) and Ghostty (test `kitty: composed text with report all`) send it.
- 2026-10-14: what gpui hides from the kitty protocol: a key alone on a modifier sends nothing (gpui reports no key event for it), and shifted punctuation reports the character it types as its key, since gpui clears Shift for it.
- 2026-10-14: on macOS, which Option key is down and whether a key repeats come from AppKit's current event: gpui rebuilds keys AppKit routes through its commands as fresh presses. As in Ghostty, `ApplePressAndHoldEnabled` is registered off, so held keys repeat instead of opening the accent menu, and a local event monitor hands Command key-ups to the focused view, since AppKit never routes them to the window.
- 2026-10-14: mouse reports follow Ghostty's rules: X10 tracking sends presses alone without modifiers, SGR names the released button, motion inside one cell sends nothing, Shift takes the mouse back for selecting. The tap follows modes 9, 1000, 1002, 1003, 1005 and 1006 as xterm holds them: one tracking and one format at a time, the last set wins, any reset ends it, and RIS clears both. alacritty drops 9 and keeps each mode apart, so its mouse bits go unread. The tap's scanner reads controls inside a sequence as vte does: C0 runs, DEL and high bytes are skipped, CAN and SUB cancel, ESC restarts, subparameters are skipped. Motion reports the first held button: left, right, middle.
- 2026-10-14: a wheel notch scrolls 3 lines, as Ghostty's discrete wheel; a trackpad scrolls its pixels. The wheel reports to a program that tracks the mouse, sends arrows on the alternate screen under mode 1007, and scrolls history otherwise.
- 2026-10-14: Cmd-C and Cmd-V copy and paste on macOS, Ctrl-Shift-C and Ctrl-Shift-V elsewhere; Cmd-press, Ctrl-press off macOS, opens an OSC 8 target or a URL Ely's `links` finds in the wrapped line. Copies drop the newline alacritty ends a whole line with, as Ghostty's do. Bracketed pastes lose ESC and Ctrl-C, as alacritty's do; plain pastes end lines with CR. Typing and pasting clear the selection. Copy on select and OSC 52 writes to `p` or `s` go to the primary selection on Linux, as Ghostty's do; macOS and Windows have none, so they go to the clipboard.
- 2026-10-14: a key's release goes out only when the terminal saw its press, so a key a binding takes sends no release, as in kitty.
- 2026-10-14: find opens on Cmd-F (Ctrl-Shift-F off macOS) beside the grid, outside the `Terminal` key context, so its keys never reach the program. Matches wash in Ely's `warning` color, the current one stronger; the newest is current first, Enter steps older and Shift-Enter newer. Shift-Enter binds under `TerminalFind > ElyInput`, the context of Ely's text input, whose own Shift-Enter binding takes the key. Find reads the grid as it shows: combining marks ride their cells, hidden cells are blank, wrapped rows join, words are Unicode; alacritty's own search reads no marks and knows only ASCII word edges. New output, a resize and a settings change search again; the current match stays the same occurrence: its line kept, grown or cut at its end, held under the same line above or in its place, before such a line elsewhere, nearest where scrolling moved it; else the nearest by line, then column. Searching and following take one pass over the text and the matches.
- 2026-10-14: the program hears focus in and out under mode 1004 when the terminal's focus or the window's activation changes. The window wears the program's title, the app's name while it names none. A bell is logged and makes no sound. A full reset, `ESC c`, empties alacritty's title and sends only `CursorBlinkingChange`, in the parser's order, synchronized updates too; on that event the view replays the title through `set_options`, which sends it.
- 2026-10-14: the title bar is transparent, as Ghostty's: the content runs under it, Ely's column headers drag the window, and the terminal's header shows the program's title. macOS draws its traffic lights at Ely's origin; elsewhere Ely draws the controls, so windows ask for client decorations, which only Linux reads, and Ely's `ResizeBorder` gives the edges. Cmd-B and Cmd-Alt-B (Ctrl-Shift-B and Ctrl-Shift-Alt-B off macOS) toggle the sessions and right columns, kept in the settings.
- 2026-10-14: session keys are Ghostty's: Cmd-T, Cmd-W, Cmd-1 to Cmd-8, Cmd-9 for the last, Ctrl-Tab and Ctrl-Shift-Tab; off macOS Ctrl-Shift-T, Ctrl-Shift-W and Alt with the digits. A digit past the last session goes on to the program. A new session runs the Shell setting in home or in the shown session's folder, as Start in says. A session whose program ends closes its row; the last row closes the window, and with no window left the app quits. A bell in a hidden session marks its row until it is shown. A hidden terminal hears no mouse release, so hiding it ends its mouse gesture as releases would: the selection drag ends, and the program hears each held button come up. A row's title is the program's, or the app's name while it names none.
- 2026-10-14: Files shows the shown session's folder in Ely's `Tree`, not `FileTree`, which takes every path up front and drops empty folders. A folder is read off the main thread when it first opens; the root and the open folders are read again whenever the session reports a folder, so at each prompt. Git's marks come from `git status --porcelain=v2 -z -- .`, run with `--no-optional-locks`, so it never holds `index.lock` against the user's own git, and under the user's `status.showUntrackedFiles`, so a home folder kept in git stays quick. An untracked folder marks what it holds. On macOS, whose file systems ignore Unicode forms, a name keeps its form on disk and meets Git's mark in composed form, as git's `core.precomposeunicode` writes it. A label built from a path shows each control character as its picture, `␊` for a newline: gpui shapes no newline, and a file may be named with one. A name not in UTF-8 keeps its bytes: its label shows it lossily, and its tree key adds the bytes after a NUL, which no path holds, so no two names share a key. A program without shell integration gets a line in the right column until it reports a folder. A control in a column header keeps its presses: Ely's header zooms the window on any double press.
- 2026-10-14: git runs in English with `--literal-pathspecs` and without optional locks. Paths stay git's bytes until shown, so a name not in UTF-8 still names its own file; off Unix git writes UTF-8. Status reads porcelain v2. Paths to stage and unstage go in on stdin, NUL-ended (`--pathspec-from-file`), so any name and any count pass; an empty list is refused, since git would take it as the whole tree. Unstaging is `git reset`, which works before the first commit, and a staged rename unstages with its old path; a copy is a new file, its source no part of it. A diff is git's own, without external tools or text converters, a conflict against HEAD, our side, so a file we deleted reads as new; it is read into Ely's stretches; a binary file has none, and an untracked folder none either. Without an index git exits 1 for a difference and a failure alike; only a difference prints. What git warns of while it works goes to the log. The log needs a commit at HEAD: git refuses it before the first.
- 2026-10-14: the Git panel shows HEAD's branch, or its short commit while detached; Ely's `ChangesList` of conflicted, staged, unstaged and untracked files; Ely's `CommitInput`; Ely's `CommitList` of the last 50 commits. A row's press opens its diff in Ely's fullscreen `Dialog` under the title bar, in Ely's `DiffViewer`, unified or split; a binary file, an untracked folder and a change of no line say so instead. Every control Ely draws works: stage, unstage, stage all, unstage all, amend, and discard, which asks first in Ely's `ConfirmDialog`: an edit goes back to the index (`git restore`); a new file, untracked or only intended to be added, is deleted (`git clean`, `git rm -f`). Git's clean passes over a repository of its own without a word, so a clean that removed nothing is an error. Actions run off the main thread, each after the one asked before it; a failure shows in Ely's `Alert` with git's words until dismissed or the next action, and after any action Files reads its marks again. A folder change drops the open diff, and one still loading, and blanks the view unless the new folder lies inside the shown work tree, so a cd within it does not blink; no action runs until the shown folder has read, so none reaches the repository left behind. A commit empties only the fields that still hold what it committed, and only once the shown folder has read and is in the same repository: a draft typed while it ran, or while a folder read, stays. A path shows on one line and once: as it is, or quoted as git quotes a name with control characters, quotes, backslashes or bytes not in UTF-8; a folder drops git's trailing slash, since no file shares its name. A section lists 500 files at most, and a line says how many are listed: Ely's list draws every row, and gpui copies every row's hitboxes and paint each frame, so 3000 rows halved the terminal's frames. The Git body is a cached view, so a terminal's output does not draw it again; it comes back from the Files tab with its lists scrolled to the top, since a view cached while hidden drops its widgets' state. Files stays uncached, so its tree keeps its open folders: Ely's `Tree` draws only the rows in view.
- 2026-10-14: Cmd-, opens the settings window, or brings the open one forward, and Cmd-W closes it; off macOS Ctrl-, and Ctrl-Shift-W, as Ghostty's. Categories sit in Ely's `SettingsLayout`, rows in its `SettingsRow`; a category joins the list with its rows. Each change goes through `SettingsStore::update`, which checks and saves, and every view reads the global, so it applies at once. A shell saves only when it names a program the running user may run, as the system's `access` answers, ACLs too: empty for the login shell, a file at a full path, or a name found in one of `PATH`'s full folders; a relative folder counts for none, since it would hang on each session's own folder. On Windows a name without an extension means its `.exe`, as `CreateProcess` reads it; a name with one keeps it. A program whose path is not UTF-8 counts for none: a session starts its program by text. A session runs that same full path, so the check and the start agree; else the row says why and the saved one stays, since a bad shell stops the next start. The window takes focus inside when it opens, so its keys find its context. The app quits with its last terminal window: settings alone hold no terminal.
- 2026-10-14: settings refuse unknown fields; a bad settings file stops the start and is never overwritten.
- 2026-10-14: Appearance shows every built-in theme as Ely's `RadioCard` in a `SimpleGrid`, each over a small window in the theme's colors. Separate dark theme copies the theme into `dark_theme`, so turning it on changes nothing until a dark card is picked. A theme change re-dresses the chrome at once. Font family comes from Ely's `FontPicker`; size, line height and padding from its `NumberInput`, which saves a number on Enter, on leaving the field and on each step. A font saves, and a settings file starts, only when gpui loads it as the terminal draws it: gpui falls back to another font without a word and loads none without an `m`, so the terminal draws with no font but its own. The cursor preview is a prompt in the terminal's font and theme, its cursor drawn as the terminal draws it, blinking on the terminal's beat. Opacity moves by whole percents, so the saved fraction carries no float noise. A change the store refuses leaves the setting as it was, and the page says why at its top; a number field drops its draft, and the font picker shows the saved family again. The settings window opens at 900 by 640, room for three theme columns.
- 2026-10-14: Terminal shows scrollback lines, Option as Alt, on macOS only, since elsewhere Alt is Alt, and copy on select. The engine reads each when it needs it, so a change applies at once to every session; a smaller scrollback drops the history past it.
- 2026-10-14: the main window lets the desktop through while Background opacity is under 1, blurred or clear as Background blur says, through gpui's `Blurred` (macOS's NSVisualEffectView, Windows' acrylic) or `Transparent`; at 1 it is `Opaque`. The workspace sets it as the settings change. Ely's `ColumnShell::glass`, added to Ely for this, grounds the columns in the palette's glass, which the opacity sets, so the title bar and every column let the desktop through alike; the palette's `bg` stays solid, so a dialog, the Git diff among them, hides what lies under it. The terminal paints no ground over the glass, or the two would stack; a program's own background (OSC 11) paints over it. Ely's own themes pass their palette too, Ely's colors with the glass set. The settings window stays opaque.
- 2026-10-15: on Wayland the window asks for `ext_background_effect_v1` beside gpui's `org_kde_kwin_blur`. A guest connection on gpui's own display binds it, takes the effect for the window's surface once, and blurs the window's pane: the surface less Ely's resize margin on each free edge of a client-drawn window, worked out each frame and sent only when it changes; it goes and comes back with Blurred and lands at the surface's next commit, which every frame makes. The guest connection reads the display only while the window opens, before gpui's loop runs, and is never dropped: a drop destroys its proxies through the display, which gpui may close first. The log names what the compositor offers, so which way blur goes: `ext_background_effect_v1`, gpui's `org_kde_kwin_blur`, or none, the desktop clear. Its test runs a `wayland-server` compositor on a socket pair.
- 2026-10-15: on a client-drawn window, so on Linux, Ely's `ResizeBorder` paints its pane solid and shadowed under the content, which kept the desktop from showing at all. `ResizeBorder::glass`, added to Ely for this, leaves the pane to the content while the window is see-through: no ground, nor the shadow gpui draws under the box, which would tint it. So the blur covers the pane alone and the resize margin stays clear. On X11 the window names its pane in `_KDE_NET_WM_BLUR_BEHIND_REGION` (CARDINAL, 32: x, y, width, height in the window's pixels), as Ghostty names its own, and drops the property when Blurred goes; KWin reads it, other compositors pass it by. It goes over a connection of ELYTerminal's own to `$DISPLAY`, which gpui opens too: a property belongs to the window, whoever sets it. gpui's own `org_kde_kwin_blur` on KDE's Wayland still covers the whole surface, margin included, beyond ELYTerminal's reach.
- 2026-10-15: the macOS menu bar is the PRD's: ELYTerminal (Settings…, Quit), Shell (New Session, Close Session), Edit (Copy, Paste, Select All, Find), View (Toggle Sessions, Toggle Right Panel, Bigger, Smaller, Reset Size), Window (Minimize, Zoom, then the windows macOS lists). An item shows the key bound to its action, so the menus are set after the bindings; Copy, Paste and Select All go through AppKit's `copy:`, `paste:` and `selectAll:`, as gpui's `OsAction` maps them. The new keys are Ghostty's: Cmd-Q, Cmd-A, Cmd-= and Cmd-+, Cmd-minus, Cmd-0, Cmd-M. Off macOS Quit and Select All take Ctrl-Shift, since Ctrl with a letter types a control byte; the font's size takes plain Ctrl with =, +, minus and 0, which type none, as in Ghostty, Alacritty and Windows Terminal; Minimize has no key there. Bigger and Smaller move every session's font a point, inside the Size range, and Reset Size goes back to the setting; nothing saves the change, as in Ghostty. Select All runs from the first character in the history to the last on the screen, the blanks around them left out, as Ghostty's; copy on select takes it, and a blank grid selects nothing.