Merge remote-tracking branch 'origin/blitz/command-bar' into command-bar/149-web-bar

web/src/attach.ts

@@ -5,6 +5,7 @@ import "@xterm/xterm/css/xterm.css";
 
 import { attachWsUrl } from "./routes.js";
 import { FOCUS_SIDEBAR_EVENT } from "./catalog.js";
+import { CommandSet, defineCommands } from "./commands.js";
 import { escapeHtml } from "./html.js";
 import { INITIAL_RECONNECT_MS, MAX_RECONNECT_MS } from "./reconnect.js";
 import { applyModsToChar, cursorSeq, tildeSeq } from "./keys.js";
@@ -13,6 +14,15 @@ import { splitCommand, toolIconSvg } from "./toolIcon.js";
 import type { ClientControl, Uuid } from "./types.js";
 import { WebglPolicy } from "./webglRenderer.js";
 
+// The pane's half of the command registry (#148): plain Escape hands the
+// keyboard back to the session list, the pair to the list's Tab.
+const paneKeys = new CommandSet(
+  defineCommands({
+    "pane.focusList": () => document.dispatchEvent(new CustomEvent(FOCUS_SIDEBAR_EVENT)),
+  }),
+  { preventDefault: false },
+);
+
 /** One budget for the whole page — see webglRenderer.ts for why contexts are
  *  rationed rather than handed to every connection. */
 const webglPolicy = new WebglPolicy();
@@ -56,8 +66,6 @@ export interface AttachOptions {
   shouldReconnect?: (sessionId: Uuid, code: number) => boolean;
 }
 
-
-
 /** What the header shows about the session (name / command). Optional — falls
  * back to a short session id when the session isn't known yet. */
 export interface AttachInfo {
@@ -210,12 +218,12 @@ export function createAttachConnection(
   }
 
   // Plain Escape hands the keyboard back to the session list instead of the
-  // shell/app. `false` tells xterm to skip its own handling of this event.
+  // shell/app. `false` tells xterm to skip its own handling of this event —
+  // which is also why the set doesn't `preventDefault`: swallowing here is
+  // xterm's return value, not the browser's.
   term.attachCustomKeyEventHandler((e) => {
-    if (e.type !== "keydown" || e.key !== "Escape") return true;
-    if (e.ctrlKey || e.altKey || e.metaKey || e.shiftKey) return true;
-    document.dispatchEvent(new CustomEvent(FOCUS_SIDEBAR_EVENT));
-    return false;
+    if (e.type !== "keydown") return true;
+    return !paneKeys.handle(e);
   });
 
   // Touch scrolling: xterm's built-in touch handling is jittery (drags crawl a

web/src/catalog.ts

@@ -2,7 +2,8 @@ import { escapeHtml } from "./html.js";
 import { ApiRequestError, getDaemonInfo, killSession, renameSession } from "./api.js";
 import { openForceKillDialog } from "./killDialog.js";
 import { openContextMenu } from "./contextMenu.js";
-import { isTypingTarget, toggleHelp } from "./help.js";
+import { toggleHelp } from "./help.js";
+import { CommandSet, defineCommands } from "./commands.js";
 import { CatalogStore } from "./events.js";
 import type { InTheWay, Session } from "./types.js";
 import {
@@ -669,24 +670,30 @@ export function renderSidebar(store: CatalogStore, opts: SidebarOptions = {}): S
     applyNav();
   };
 
-  treeHost.addEventListener("keydown", (e) => {
-    if (e.ctrlKey || e.altKey || e.metaKey) return;
-    // The inline rename field lives inside a row and owns its own keys.
-    if (isTypingTarget(e.target)) return;
-    if (e.key === "j" || e.key === "ArrowDown") moveNav(1);
-    else if (e.key === "k" || e.key === "ArrowUp") moveNav(-1);
-    else if (e.key === "Enter") activateNav();
-    else if (e.key === "Tab") document.dispatchEvent(new CustomEvent(FOCUS_PANE_EVENT));
-    else if (e.key === "c") toggleHighlightedFolder();
-    else if (e.key === "x") {
-      const hit = highlightedSession();
-      if (hit) void requestKill(hit.session, sessionName(hit.session));
-    } else if (e.key === "r") {
-      const hit = highlightedSession();
-      if (hit) beginRename(hit.row, hit.session);
-    } else return;
-    e.preventDefault();
-  });
+  // The session list's half of the command registry (#148). One set per
+  // sidebar, so a second sidebar (tests, hot reload) drives its own rows; the
+  // labels and chords still come from the one registry.
+  const listKeys = new CommandSet(
+    defineCommands({
+      "list.next": () => moveNav(1),
+      "list.prev": () => moveNav(-1),
+      "list.activate": () => activateNav(),
+      "list.toggleFolder": () => toggleHighlightedFolder(),
+      "list.rename": () => {
+        const hit = highlightedSession();
+        if (hit) beginRename(hit.row, hit.session);
+      },
+      "list.kill": () => {
+        const hit = highlightedSession();
+        if (hit) void requestKill(hit.session, sessionName(hit.session));
+      },
+      "list.focusPane": () => document.dispatchEvent(new CustomEvent(FOCUS_PANE_EVENT)),
+    }),
+  );
+
+  // The inline rename field lives inside a row and owns its own keys; the set's
+  // plain-key rule keeps this walk out of it.
+  treeHost.addEventListener("keydown", (e) => listKeys.handle(e));
 
   /** Signature of what is currently on screen — see `treeSignature`. */
   let renderedSignature: string | null = null;

web/src/commands.test.ts

@@ -0,0 +1,236 @@
+// @vitest-environment happy-dom
+import { describe, expect, it, vi } from "vitest";
+
+import {
+  COMMAND_SPECS,
+  CommandSet,
+  DEFAULT_LEADER,
+  canonicalizeKey,
+  defineCommands,
+  isTypingTarget,
+  keyCaps,
+  publishedCommands,
+} from "./commands.js";
+
+function key(k: string, init: KeyboardEventInit = {}): KeyboardEvent {
+  return new KeyboardEvent("keydown", { key: k, cancelable: true, ...init });
+}
+
+function el(html: string): HTMLElement {
+  const d = document.createElement("div");
+  d.innerHTML = html;
+  return d.firstElementChild as HTMLElement;
+}
+
+/** Dispatch on a target, so `isTypingTarget` sees something other than null. */
+function pressOn(set: CommandSet, target: HTMLElement, k: string, init?: KeyboardEventInit): boolean {
+  const e = key(k, init);
+  Object.defineProperty(e, "target", { value: target });
+  return set.handle(e);
+}
+
+describe("command specs", () => {
+  it("has a unique id and at least one chord per command", () => {
+    const ids = COMMAND_SPECS.map((s) => s.id);
+    expect(new Set(ids).size).toBe(ids.length);
+    for (const spec of COMMAND_SPECS) {
+      expect(spec.keys.length).toBeGreaterThan(0);
+      expect(spec.label.length).toBeGreaterThan(0);
+    }
+  });
+
+  it("binds each chord once within a scope", () => {
+    const seen = new Set<string>();
+    for (const spec of COMMAND_SPECS) {
+      for (const k of spec.keys) {
+        const slot = `${spec.scope}:${k}`;
+        expect(seen.has(slot)).toBe(false);
+        seen.add(slot);
+      }
+    }
+  });
+
+  it("rejects a handler for an id that isn't in the registry", () => {
+    expect(() => defineCommands({ "nope.missing": () => {} })).toThrow(/unknown command id/);
+  });
+
+  it("carries every spec field onto the defined command", () => {
+    const [cmd] = defineCommands({ "spawn.open": () => {} });
+    expect(cmd).toMatchObject({ id: "spawn.open", keys: ["n"], scope: "global" });
+  });
+});
+
+describe("canonicalizeKey", () => {
+  it("spells keys the way the TUI's InputKey::canonical does", () => {
+    expect(canonicalizeKey(key("n"))).toBe("n");
+    expect(canonicalizeKey(key("N", { shiftKey: true }))).toBe("N");
+    expect(canonicalizeKey(key("?", { shiftKey: true }))).toBe("?");
+    expect(canonicalizeKey(key("a", { ctrlKey: true }))).toBe("ctrl-a");
+    expect(canonicalizeKey(key("Escape"))).toBe("esc");
+    expect(canonicalizeKey(key("Enter"))).toBe("enter");
+    expect(canonicalizeKey(key("Tab"))).toBe("tab");
+    expect(canonicalizeKey(key("Tab", { shiftKey: true }))).toBe("backtab");
+    expect(canonicalizeKey(key("ArrowDown"))).toBe("down");
+  });
+
+  it("folds a modified letter to lower case with an explicit shift-", () => {
+    expect(canonicalizeKey(key("H", { ctrlKey: true, shiftKey: true }))).toBe("ctrl-shift-h");
+    expect(canonicalizeKey(key("h", { ctrlKey: true, shiftKey: true }))).toBe("ctrl-shift-h");
+  });
+
+  it("has no canonical form for a modifier pressed alone", () => {
+    expect(canonicalizeKey(key("Control", { ctrlKey: true }))).toBeNull();
+    expect(canonicalizeKey(key("Shift", { shiftKey: true }))).toBeNull();
+  });
+});
+
+describe("keyCaps", () => {
+  it("renders one cap per modifier and key", () => {
+    expect(keyCaps("ctrl-shift-h")).toEqual(["Ctrl", "Shift", "H"]);
+    expect(keyCaps("enter")).toEqual(["Enter"]);
+    expect(keyCaps("j")).toEqual(["j"]);
+    expect(keyCaps("N")).toEqual(["N"]);
+    expect(keyCaps("?")).toEqual(["?"]);
+    expect(keyCaps("ctrl-a ctrl-k")).toEqual(["Ctrl", "A", "then", "Ctrl", "K"]);
+  });
+});
+
+describe("CommandSet", () => {
+  it("runs the command bound to a chord, and swallows the browser default", () => {
+    const run = vi.fn();
+    const set = new CommandSet(defineCommands({ "spawn.open": run }));
+    const e = key("n");
+    expect(set.handle(e)).toBe(true);
+    expect(run).toHaveBeenCalledTimes(1);
+    expect(e.defaultPrevented).toBe(true);
+  });
+
+  it("leaves an unbound key alone", () => {
+    const set = new CommandSet(defineCommands({ "spawn.open": vi.fn() }));
+    const e = key("q");
+    expect(set.handle(e)).toBe(false);
+    expect(e.defaultPrevented).toBe(false);
+  });
+
+  it("treats a modified key as a different binding", () => {
+    const run = vi.fn();
+    const set = new CommandSet(defineCommands({ "spawn.open": run }));
+    expect(set.handle(key("n", { ctrlKey: true }))).toBe(false);
+    expect(set.handle(key("n", { metaKey: true }))).toBe(false);
+    expect(run).not.toHaveBeenCalled();
+  });
+
+  it("runs every alias of a command", () => {
+    const run = vi.fn();
+    const set = new CommandSet(defineCommands({ "list.next": run }));
+    set.handle(key("j"));
+    set.handle(key("ArrowDown"));
+    expect(run).toHaveBeenCalledTimes(2);
+  });
+
+  it("keeps plain keys deaf inside a form field, and chorded ones live", () => {
+    const plain = vi.fn();
+    const chorded = vi.fn();
+    const set = new CommandSet(
+      defineCommands({ "spawn.open": plain, "focus.toggle": chorded }),
+    );
+    const input = el("<input>");
+    expect(pressOn(set, input, "n")).toBe(false);
+    expect(plain).not.toHaveBeenCalled();
+    expect(pressOn(set, input, "H", { ctrlKey: true, shiftKey: true })).toBe(true);
+    expect(chorded).toHaveBeenCalledTimes(1);
+  });
+
+  it("keeps pane commands live inside the terminal's textarea", () => {
+    const run = vi.fn();
+    const set = new CommandSet(defineCommands({ "pane.focusList": run }), {
+      preventDefault: false,
+    });
+    const textarea = el('<textarea class="xterm-helper-textarea"></textarea>');
+    const e = key("Escape");
+    Object.defineProperty(e, "target", { value: textarea });
+    expect(set.handle(e)).toBe(true);
+    expect(run).toHaveBeenCalledTimes(1);
+    // xterm is told to swallow by the return value, not by the browser default.
+    expect(e.defaultPrevented).toBe(false);
+  });
+});
+
+describe("the leader", () => {
+  it("defaults to the TUI's ctrl-a", () => {
+    expect(DEFAULT_LEADER).toBe("ctrl-a");
+  });
+
+  it("holds the leader as a partial chord instead of selecting the page", () => {
+    const set = new CommandSet(defineCommands({ "spawn.open": vi.fn() }), {
+      leader: DEFAULT_LEADER,
+    });
+    const e = key("a", { ctrlKey: true });
+    expect(set.handle(e)).toBe(true);
+    expect(e.defaultPrevented).toBe(true);
+  });
+
+  it("swallows the key after the leader rather than running its plain binding", () => {
+    const run = vi.fn();
+    const set = new CommandSet(defineCommands({ "spawn.open": run }), {
+      leader: DEFAULT_LEADER,
+    });
+    set.handle(key("a", { ctrlKey: true }));
+    expect(set.handle(key("n"))).toBe(true);
+    expect(run).not.toHaveBeenCalled();
+    // The next key is an ordinary one again.
+    set.handle(key("n"));
+    expect(run).toHaveBeenCalledTimes(1);
+  });
+
+  it("forgets a held leader once the chord timeout passes", () => {
+    const run = vi.fn();
+    let now = 0;
+    const set = new CommandSet(defineCommands({ "spawn.open": run }), {
+      leader: DEFAULT_LEADER,
+      chordTimeoutMs: 1000,
+      now: () => now,
+    });
+    set.handle(key("a", { ctrlKey: true }));
+    now = 1500;
+    set.handle(key("n"));
+    expect(run).toHaveBeenCalledTimes(1);
+  });
+
+  it("leaves select-all alone in a real form field", () => {
+    const set = new CommandSet(defineCommands({ "spawn.open": vi.fn() }), {
+      leader: DEFAULT_LEADER,
+    });
+    const input = el("<input>");
+    const e = key("a", { ctrlKey: true });
+    Object.defineProperty(e, "target", { value: input });
+    expect(set.handle(e)).toBe(false);
+    expect(e.defaultPrevented).toBe(false);
+  });
+});
+
+describe("publishing", () => {
+  it("lists a constructed set's commands, replacing an id rather than doubling it", () => {
+    new CommandSet(defineCommands({ "list.kill": () => {} }));
+    new CommandSet(defineCommands({ "list.kill": () => {} }));
+    const ids = publishedCommands().map((c) => c.id);
+    expect(ids.filter((id) => id === "list.kill")).toEqual(["list.kill"]);
+  });
+
+  it("keeps published commands in registry order", () => {
+    const order = COMMAND_SPECS.map((s) => s.id);
+    const ids = publishedCommands().map((c) => c.id);
+    expect(ids).toEqual(order.filter((id) => ids.includes(id)));
+  });
+});
+
+describe("isTypingTarget", () => {
+  it("is true for form fields and editable nodes, false otherwise", () => {
+    expect(isTypingTarget(el("<input>"))).toBe(true);
+    expect(isTypingTarget(el("<textarea></textarea>"))).toBe(true);
+    expect(isTypingTarget(el("<select></select>"))).toBe(true);
+    expect(isTypingTarget(el('<div contenteditable="true"></div>'))).toBe(true);
+    expect(isTypingTarget(el("<button></button>"))).toBe(false);
+    expect(isTypingTarget(null)).toBe(false);
+  });
+});

web/src/commands.ts

@@ -0,0 +1,386 @@
+// The web client's command registry (#148). One entry per command — a stable
+// id, a plain-language label, the key chord it answers to, and a `run()` — so
+// there is exactly one list of what the client can do. The `?` overlay renders
+// from it (`help.ts`), and every keybinding is dispatched through it; a command
+// added here is bound and documented in the same edit.
+//
+// Keys are canonical strings, the same spelling the TUI's `InputKey::canonical`
+// produces (`ctrl-shift-h`, `enter`, `esc`, `n`, `N`) and chords are those
+// joined by a space (`ctrl-a ctrl-k`). Matching the TUI's spelling is what lets
+// docs/COMMAND-BAR.md describe one key model for both clients.
+
+/** Where a command's keys are listened for. `global` is the window, `list` the
+ *  sidebar's session tree, `pane` the attached terminal, `overlay` the help
+ *  dialog while it is up. */
+export type CommandScope = "global" | "list" | "pane" | "overlay";
+
+export interface CommandSpec {
+  /** Stable identifier. Never rendered; safe to bind config and tests to. */
+  id: string;
+  /** Plain-language label — what the `?` overlay and (later) the command bar
+   *  show. */
+  label: string;
+  /** Help-overlay section. Groups render in the order they first appear here. */
+  group: string;
+  /** Canonical chords that run it. The first is the one shown to the operator;
+   *  the rest are aliases (`j` and `down`). */
+  keys: string[];
+  scope: CommandScope;
+}
+
+export interface Command extends CommandSpec {
+  run: () => void;
+}
+
+/** Every command the web client has. The single list this issue exists to
+ *  create: labels, chords and grouping live here and nowhere else. */
+export const COMMAND_SPECS: readonly CommandSpec[] = [
+  {
+    id: "spawn.open",
+    label: "Open the spawn form",
+    group: "Sessions",
+    keys: ["n"],
+    scope: "global",
+  },
+  {
+    id: "spawn.fastForward",
+    label: "Spawn a session with every default resolved",
+    group: "Sessions",
+    keys: ["N"],
+    scope: "global",
+  },
+  {
+    id: "focus.toggle",
+    label: "Move the keyboard between the session list and the pane",
+    group: "Session list",
+    keys: ["ctrl-shift-h"],
+    scope: "global",
+  },
+  {
+    id: "list.next",
+    label: "Highlight the next session",
+    group: "Session list",
+    keys: ["j", "down"],
+    scope: "list",
+  },
+  {
+    id: "list.prev",
+    label: "Highlight the previous session",
+    group: "Session list",
+    keys: ["k", "up"],
+    scope: "list",
+  },
+  {
+    id: "list.activate",
+    label: "Open the highlighted session, or expand a folder",
+    group: "Session list",
+    keys: ["enter"],
+    scope: "list",
+  },
+  {
+    id: "list.toggleFolder",
+    label: "Collapse or expand the highlighted folder",
+    group: "Session list",
+    keys: ["c"],
+    scope: "list",
+  },
+  {
+    id: "list.rename",
+    label: "Rename the highlighted session",
+    group: "Session list",
+    keys: ["r"],
+    scope: "list",
+  },
+  {
+    id: "list.kill",
+    label: "Kill the highlighted session",
+    group: "Session list",
+    keys: ["x"],
+    scope: "list",
+  },
+  {
+    id: "list.focusPane",
+    label: "Send the keyboard to the pane",
+    group: "Session list",
+    keys: ["tab"],
+    scope: "list",
+  },
+  {
+    id: "pane.focusList",
+    label: "Hand the keyboard back to the session list, from the pane",
+    group: "Session list",
+    keys: ["esc"],
+    scope: "pane",
+  },
+  {
+    id: "help.toggle",
+    label: "Show or hide this help",
+    group: "Help",
+    keys: ["?"],
+    scope: "global",
+  },
+  {
+    id: "help.close",
+    label: "Close the help overlay or an open menu",
+    group: "Help",
+    keys: ["esc"],
+    scope: "overlay",
+  },
+  {
+    id: "debug.toggleHud",
+    label: "Toggle the debug HUD",
+    group: "Debug",
+    keys: ["ctrl-shift-d"],
+    scope: "global",
+  },
+];
+
+const SPEC_BY_ID = new Map(COMMAND_SPECS.map((s) => [s.id, s]));
+
+/** Attach handlers to specs, by id. Throws on an unknown id, so a typo is a
+ *  test failure rather than a key that silently does nothing. */
+export function defineCommands(handlers: Record<string, () => void>): Command[] {
+  return Object.entries(handlers).map(([id, run]) => {
+    const spec = SPEC_BY_ID.get(id);
+    if (!spec) throw new Error(`unknown command id: ${id}`);
+    return { ...spec, run };
+  });
+}
+
+// ---- what the help overlay renders ----
+
+const published = new Map<string, Command>();
+
+/** Record commands as bound. Re-registering an id replaces it, so a second
+ *  sidebar (tests, hot reload) doesn't duplicate rows in the overlay. */
+export function publishCommands(cmds: Command[]): void {
+  for (const c of cmds) published.set(c.id, c);
+}
+
+/** Every bound command, in `COMMAND_SPECS` order. */
+export function publishedCommands(): Command[] {
+  return COMMAND_SPECS.map((s) => published.get(s.id)).filter((c): c is Command => c !== undefined);
+}
+
+// ---- key canonicalisation ----
+
+const NAMED: Record<string, string> = {
+  Escape: "esc",
+  Enter: "enter",
+  Tab: "tab",
+  Backspace: "backspace",
+  ArrowUp: "up",
+  ArrowDown: "down",
+  ArrowLeft: "left",
+  ArrowRight: "right",
+  Home: "home",
+  End: "end",
+  PageUp: "pageup",
+  PageDown: "pagedown",
+  Delete: "delete",
+  " ": "space",
+};
+
+/** The canonical string for one keydown. Mirrors the TUI's
+ *  `InputKey::canonical`: modifier prefixes in ctrl/alt/shift order, then the
+ *  key. A shifted character already spells itself (`N`, `?`), so `shift-` is
+ *  only written when another modifier is present and the char was folded to
+ *  lower case. */
+export function canonicalizeKey(e: KeyboardEvent): string | null {
+  if (!e.key) return null;
+  // Modifier keys pressed alone are never a binding.
+  if (e.key === "Control" || e.key === "Alt" || e.key === "Shift" || e.key === "Meta") return null;
+  const named = NAMED[e.key];
+  if (named === "tab" && e.shiftKey) return "backtab";
+  let out = "";
+  if (e.ctrlKey) out += "ctrl-";
+  if (e.altKey) out += "alt-";
+  if (e.metaKey) out += "meta-";
+  if (named) {
+    if (e.shiftKey) out += "shift-";
+    return out + named;
+  }
+  if (e.key.length === 1) {
+    if (out === "") return e.key;
+    if (e.shiftKey) out += "shift-";
+    return out + e.key.toLowerCase();
+  }
+  if (e.shiftKey) out += "shift-";
+  return out + e.key.toLowerCase();
+}
+
+const MOD_PREFIX = /^(ctrl|alt|meta|shift)-/;
+
+/** True when a chord carries a modifier or more than one key. Plain single-key
+ *  chords are the ones that stay deaf inside form fields. */
+function isChorded(chord: string): boolean {
+  return chord.includes(" ") || MOD_PREFIX.test(chord);
+}
+
+/** True when the event target swallows plain keystrokes — a form field, or the
+ *  hidden textarea xterm types into. Every plain single-key binding is deaf in
+ *  the same places. */
+export function isTypingTarget(target: EventTarget | null): boolean {
+  const el = target as HTMLElement | null;
+  if (!el || typeof el.tagName !== "string") return false;
+  return (
+    el.tagName === "INPUT" ||
+    el.tagName === "TEXTAREA" ||
+    el.tagName === "SELECT" ||
+    el.isContentEditable
+  );
+}
+
+/** xterm's offscreen textarea. It is a typing target like any other, but it is
+ *  also where the leader has to work — a pane is exactly where the operator
+ *  needs the escape hatch (docs/COMMAND-BAR.md). */
+function isTerminalTextarea(target: EventTarget | null): boolean {
+  const el = target as HTMLElement | null;
+  return !!el && typeof el.className === "string" && el.classList?.contains("xterm-helper-textarea");
+}
+
+// ---- display ----
+
+const CAPS: Record<string, string> = {
+  ctrl: "Ctrl",
+  alt: "Alt",
+  meta: "Meta",
+  shift: "Shift",
+  esc: "Esc",
+  enter: "Enter",
+  tab: "Tab",
+  backtab: "Shift Tab",
+  backspace: "Backspace",
+  up: "Up",
+  down: "Down",
+  left: "Left",
+  right: "Right",
+  home: "Home",
+  end: "End",
+  pageup: "PgUp",
+  pagedown: "PgDn",
+  delete: "Del",
+  space: "Space",
+};
+
+/** Keycaps for a chord, left to right: `ctrl-shift-h` → Ctrl, Shift, H. A
+ *  multi-key chord separates its keys with a `then` cap. */
+export function keyCaps(chord: string): string[] {
+  const caps: string[] = [];
+  for (const [i, key] of chord.split(" ").entries()) {
+    if (i > 0) caps.push("then");
+    const parts = key.split("-");
+    // A bare `-` key splits into two empties; treat it as the key itself.
+    if (parts.every((p) => p === "")) {
+      caps.push("-");
+      continue;
+    }
+    const last = parts.pop() as string;
+    const mods = parts.filter((p) => p !== "");
+    for (const m of mods) caps.push(CAPS[m] ?? m);
+    caps.push(CAPS[last] ?? (mods.length > 0 && last.length === 1 ? last.toUpperCase() : last));
+  }
+  return caps;
+}
+
+// ---- dispatch ----
+
+/** Default leader, mirroring the TUI's `[tui].leader`. `ctrl-a` is select-all
+ *  in a browser, so a set that owns the leader `preventDefault`s it. */
+export const DEFAULT_LEADER = "ctrl-a";
+
+/** How long a partial chord waits for its next key — the TUI's
+ *  `chord_timeout_ms` default. */
+export const DEFAULT_CHORD_TIMEOUT_MS = 1000;
+
+export interface CommandSetOptions {
+  /** Canonical leader key. A set given one holds every leader press as a
+   *  pending chord, whether or not anything is bound behind it yet. */
+  leader?: string | null;
+  chordTimeoutMs?: number;
+  /** Call `preventDefault()` on a handled key. Off for the terminal's own key
+   *  handler, which swallows by returning `false` to xterm instead. */
+  preventDefault?: boolean;
+  /** Clock, for tests. */
+  now?: () => number;
+}
+
+/** A group of commands listening on one surface. Resolves a keydown to a
+ *  command the way the TUI's `ChordState` does: hold while the sequence is a
+ *  strict prefix of some binding, otherwise resolve and dispatch. */
+export class CommandSet {
+  private readonly byChord = new Map<string, Command>();
+  private readonly leader: string | null;
+  private readonly timeout: number;
+  private readonly preventDefault: boolean;
+  private readonly now: () => number;
+  private held: string[] = [];
+  private lastPress = 0;
+
+  constructor(
+    readonly commands: Command[],
+    opts: CommandSetOptions = {},
+  ) {
+    for (const c of commands) for (const k of c.keys) this.byChord.set(k, c);
+    this.leader = opts.leader ?? null;
+    this.timeout = opts.chordTimeoutMs ?? DEFAULT_CHORD_TIMEOUT_MS;
+    this.preventDefault = opts.preventDefault ?? true;
+    this.now = opts.now ?? (() => Date.now());
+    publishCommands(commands);
+  }
+
+  /** Whether any binding starts with `candidate` and continues. */
+  private isPrefix(candidate: string): boolean {
+    const marker = `${candidate} `;
+    for (const chord of this.byChord.keys()) if (chord.startsWith(marker)) return true;
+    return false;
+  }
+
+  /** Feed one keydown. Returns true when the key was consumed — dispatched, or
+   *  held as a partial chord. */
+  handle(e: KeyboardEvent): boolean {
+    const key = canonicalizeKey(e);
+    if (key === null) return false;
+    if (this.held.length > 0 && this.now() - this.lastPress > this.timeout) this.held = [];
+    const candidate = this.held.length > 0 ? `${this.held.join(" ")} ${key}` : key;
+    this.lastPress = this.now();
+
+    // The leader is a prefix by construction, so it stops being select-all
+    // before anything is bound behind it (#149 binds the first chord).
+    if (this.leader !== null && this.held.length === 0 && key === this.leader) {
+      if (isTypingTarget(e.target) && !isTerminalTextarea(e.target)) return false;
+      this.held = [key];
+      if (this.preventDefault) e.preventDefault();
+      return true;
+    }
+
+    if (this.isPrefix(candidate)) {
+      this.held.push(key);
+      if (this.preventDefault) e.preventDefault();
+      return true;
+    }
+
+    const wasChord = this.held.length > 0;
+    this.held = [];
+    const cmd = this.byChord.get(candidate);
+    if (!cmd) {
+      // A chord that resolved to nothing is still consumed: the leader took
+      // the key, so it must not also fall through to a plain binding.
+      return wasChord;
+    }
+    // Plain single-key bindings are deaf where typing happens; chorded ones are
+    // not, and neither are the pane's and the overlay's, which are only fed
+    // from the surface that owns them.
+    if (
+      !isChorded(candidate) &&
+      cmd.scope !== "pane" &&
+      cmd.scope !== "overlay" &&
+      isTypingTarget(e.target)
+    ) {
+      return false;
+    }
+    if (this.preventDefault) e.preventDefault();
+    cmd.run();
+    return true;
+  }
+}

web/src/debug.ts

@@ -2,6 +2,8 @@
 // survives reloads, flipped by a keybind (Ctrl+Shift+D), and force-enabled by
 // `?hud` in dev. A `maestro-hud-toggle` event lets the HUD re-render on change.
 
+import { CommandSet, defineCommands } from "./commands.js";
+
 const STORAGE_KEY = "maestro:hud";
 export const HUD_TOGGLE_EVENT = "maestro-hud-toggle";
 
@@ -31,12 +33,9 @@ export function toggleHud(): void {
   setHudEnabled(!isHudEnabled());
 }
 
+const hudKeys = new CommandSet(defineCommands({ "debug.toggleHud": () => toggleHud() }));
+
 /** Global keybind: Ctrl+Shift+D toggles the debug HUD. */
 export function installHudKeybind(): void {
-  window.addEventListener("keydown", (e) => {
-    if (e.ctrlKey && e.shiftKey && (e.key === "D" || e.key === "d")) {
-      e.preventDefault();
-      toggleHud();
-    }
-  });
+  window.addEventListener("keydown", (e) => hudKeys.handle(e));
 }

web/src/help.test.ts

@@ -1,14 +1,8 @@
 // @vitest-environment happy-dom
 import { afterEach, beforeEach, describe, expect, it } from "vitest";
 
-import {
-  SHORTCUTS,
-  closeHelp,
-  installHelpKeybind,
-  isHelpOpen,
-  isTypingTarget,
-  openHelp,
-} from "./help.js";
+import { keyCaps, publishedCommands } from "./commands.js";
+import { closeHelp, groupedCommands, installHelpKeybind, isHelpOpen, openHelp } from "./help.js";
 
 beforeEach(() => {
   installHelpKeybind();
@@ -30,14 +24,24 @@ function rows(): string[] {
 }
 
 describe("help overlay", () => {
-  it("renders every registered shortcut, grouped", () => {
+  it("renders exactly the commands the registry has bound, grouped", () => {
     openHelp();
-    const groups = [...document.querySelectorAll(".help-group-title")].map((h) => h.textContent);
-    expect(groups).toEqual(SHORTCUTS.map((g) => g.title));
-    expect(rows()).toEqual(SHORTCUTS.flatMap((g) => g.items.map((s) => s.keys.join(" "))));
-    expect(document.querySelectorAll(".help-desc")).toHaveLength(
-      SHORTCUTS.reduce((n, g) => n + g.items.length, 0),
+    const groups = groupedCommands();
+    expect([...document.querySelectorAll(".help-group-title")].map((h) => h.textContent)).toEqual(
+      groups.map((g) => g.title),
     );
+    expect(rows()).toEqual(
+      groups.flatMap((g) => g.items.map((c) => keyCaps(c.keys[0]).join(" "))),
+    );
+    expect([...document.querySelectorAll(".help-desc")].map((d) => d.textContent)).toEqual(
+      groups.flatMap((g) => g.items.map((c) => c.label)),
+    );
+  });
+
+  it("names each row by its command id, so a row can't drift from its command", () => {
+    openHelp();
+    expect([...document.querySelectorAll<HTMLElement>(".help-row")].map((r) => r.dataset.commandId))
+      .toEqual(publishedCommands().map((c) => c.id));
   });
 
   it("opens on ? and closes on a second ?", () => {
@@ -94,19 +98,3 @@ describe("help overlay", () => {
     expect(document.querySelectorAll(".help-overlay")).toHaveLength(1);
   });
 });
-
-describe("isTypingTarget", () => {
-  it("is true for form fields and editable nodes, false otherwise", () => {
-    const el = (html: string) => {
-      const d = document.createElement("div");
-      d.innerHTML = html;
-      return d.firstElementChild as HTMLElement;
-    };
-    expect(isTypingTarget(el("<input>"))).toBe(true);
-    expect(isTypingTarget(el("<textarea></textarea>"))).toBe(true);
-    expect(isTypingTarget(el("<select></select>"))).toBe(true);
-    expect(isTypingTarget(el('<div contenteditable="true"></div>'))).toBe(true);
-    expect(isTypingTarget(el("<button></button>"))).toBe(false);
-    expect(isTypingTarget(null)).toBe(false);
-  });
-});

web/src/help.ts

@@ -1,69 +1,15 @@
 /** Keyboard-shortcut overlay (`?`), the web counterpart of the TUI's help
- *  overlay. One registry drives both the rendering and what we claim is bound,
- *  so a binding added to `main.ts` without an entry here reads as missing. */
+ *  overlay. It renders the command registry (`commands.ts`) — the same list
+ *  that dispatches the keys — so a binding can never be documented as one
+ *  thing and do another. */
 
-export interface Shortcut {
-  /** Keycaps, rendered left to right as separate <kbd>. */
-  keys: string[];
-  description: string;
-}
-
-export interface ShortcutGroup {
-  title: string;
-  items: Shortcut[];
-}
-
-export const SHORTCUTS: ShortcutGroup[] = [
-  {
-    title: "Sessions",
-    items: [
-      { keys: ["n"], description: "Open the spawn form" },
-      { keys: ["N"], description: "Spawn a session with every default resolved" },
-    ],
-  },
-  {
-    title: "Session list",
-    items: [
-      {
-        keys: ["Ctrl", "Shift", "H"],
-        description: "Move the keyboard between the session list and the pane",
-      },
-      { keys: ["j"], description: "Highlight the next session" },
-      { keys: ["k"], description: "Highlight the previous session" },
-      { keys: ["Enter"], description: "Open the highlighted session, or expand a folder" },
-      { keys: ["c"], description: "Collapse or expand the highlighted folder" },
-      { keys: ["r"], description: "Rename the highlighted session" },
-      { keys: ["x"], description: "Kill the highlighted session" },
-      { keys: ["Tab"], description: "Send the keyboard to the pane" },
-      { keys: ["Esc"], description: "Hand the keyboard back to the session list, from the pane" },
-    ],
-  },
-  {
-    title: "Help",
-    items: [
-      { keys: ["?"], description: "Show or hide this help" },
-      { keys: ["Esc"], description: "Close the help overlay or an open menu" },
-    ],
-  },
-  {
-    title: "Debug",
-    items: [{ keys: ["Ctrl", "Shift", "D"], description: "Toggle the debug HUD" }],
-  },
-];
-
-/** True when the event target swallows plain keystrokes — a form field, or the
- *  hidden textarea xterm types into. Shared with `main.ts` so every global
- *  single-key binding is deaf in the same places. */
-export function isTypingTarget(target: EventTarget | null): boolean {
-  const el = target as HTMLElement | null;
-  if (!el || typeof el.tagName !== "string") return false;
-  return (
-    el.tagName === "INPUT" ||
-    el.tagName === "TEXTAREA" ||
-    el.tagName === "SELECT" ||
-    el.isContentEditable
-  );
-}
+import {
+  CommandSet,
+  defineCommands,
+  keyCaps,
+  publishedCommands,
+  type Command,
+} from "./commands.js";
 
 let open: { el: HTMLElement; dispose: () => void } | null = null;
 
@@ -108,7 +54,7 @@ export function openHelp(): HTMLElement {
   head.append(title, close);
   panel.appendChild(head);
 
-  for (const group of SHORTCUTS) {
+  for (const group of groupedCommands()) {
     const section = document.createElement("section");
     section.className = "help-group";
     const heading = document.createElement("h3");
@@ -116,19 +62,20 @@ export function openHelp(): HTMLElement {
     heading.textContent = group.title;
     const list = document.createElement("dl");
     list.className = "help-list";
-    for (const item of group.items) {
+    for (const cmd of group.items) {
       const row = document.createElement("div");
       row.className = "help-row";
+      row.dataset.commandId = cmd.id;
       const keys = document.createElement("dt");
       keys.className = "help-keys";
-      for (const key of item.keys) {
+      for (const key of keyCaps(cmd.keys[0])) {
         const cap = document.createElement("kbd");
         cap.textContent = key;
         keys.appendChild(cap);
       }
       const desc = document.createElement("dd");
       desc.className = "help-desc";
-      desc.textContent = item.description;
+      desc.textContent = cmd.label;
       row.append(keys, desc);
       list.appendChild(row);
     }
@@ -153,6 +100,26 @@ export function openHelp(): HTMLElement {
   return el;
 }
 
+/** The registry's commands, in registry order, bucketed into the help
+ *  overlay's sections. Groups appear in the order their first command does. */
+export function groupedCommands(): { title: string; items: Command[] }[] {
+  const groups: { title: string; items: Command[] }[] = [];
+  for (const cmd of publishedCommands()) {
+    let group = groups.find((g) => g.title === cmd.group);
+    if (!group) {
+      group = { title: cmd.group, items: [] };
+      groups.push(group);
+    }
+    group.items.push(cmd);
+  }
+  return groups;
+}
+
+// The overlay's own two commands. `help.close` is `overlay`-scoped: it is only
+// fed keys while the dialog is up.
+const helpKeys = new CommandSet(defineCommands({ "help.toggle": () => toggleHelp() }));
+const overlayKeys = new CommandSet(defineCommands({ "help.close": () => closeHelp() }));
+
 let installed = false;
 
 /** Global keybind: `?` toggles the overlay, Escape closes it. Idempotent, so a
@@ -161,16 +128,7 @@ export function installHelpKeybind(): void {
   if (installed) return;
   installed = true;
   window.addEventListener("keydown", (e) => {
-    if (e.key === "Escape" && open) {
-      e.preventDefault();
-      closeHelp();
-      return;
-    }
-    // Shift is how `?` is typed on most layouts; the others would be a
-    // different binding entirely.
-    if (e.key !== "?" || e.ctrlKey || e.altKey || e.metaKey) return;
-    if (isTypingTarget(e.target)) return;
-    e.preventDefault();
-    toggleHelp();
+    if (open && overlayKeys.handle(e)) return;
+    helpKeys.handle(e);
   });
 }

web/src/main.ts

@@ -6,7 +6,8 @@ import { renderSidebar } from "./catalog.js";
 import { ConnectionPool } from "./connections.js";
 import { installDrawer, installDrawerSwipe, requestToggleDrawer } from "./drawer.js";
 import { installHudKeybind } from "./debug.js";
-import { installHelpKeybind, isHelpOpen, isTypingTarget } from "./help.js";
+import { installHelpKeybind, isHelpOpen } from "./help.js";
+import { CommandSet, DEFAULT_LEADER, defineCommands } from "./commands.js";
 import { DaemonLink } from "./daemonLink.js";
 import { CatalogStore } from "./events.js";
 import { installRestartOverlay } from "./restartOverlay.js";
@@ -361,37 +362,48 @@ async function requestFastForward(): Promise<void> {
   });
 }
 
-// Keyboard pair (#67): `n` opens the spawn modal, `N` fast-forwards a spawn.
-// Ignored while typing anywhere (form fields, the terminal's hidden
-// textarea, search) so an attached session's keys are never hijacked.
-document.addEventListener("keydown", (e) => {
-  if (e.ctrlKey || e.altKey || e.metaKey) return;
-  if (isTypingTarget(e.target)) return;
-  // The help overlay owns the keyboard while it is up.
-  if (isHelpOpen()) return;
-  if (e.key === "n") {
-    e.preventDefault();
-    requestOpenSpawn();
-  } else if (e.key === "N") {
-    e.preventDefault();
-    void requestFastForward();
-  }
-});
+// The global half of the command registry (#148). Two sets, because they
+// differ in one thing: the help overlay owns the keyboard while it is up, so
+// the plain keys go deaf behind it while the focus chord does not — an
+// attached terminal must never be able to trap the focus keys.
+//
+// `n` opens the spawn modal, `N` fast-forwards a spawn (#67). Both are plain
+// keys, so `isTypingTarget` keeps them out of form fields and the terminal's
+// hidden textarea.
+const spawnKeys = new CommandSet(
+  defineCommands({
+    "spawn.open": () => requestOpenSpawn(),
+    "spawn.fastForward": () => void requestFastForward(),
+  }),
+);
 
 // Ctrl+Shift+H moves the keyboard between the session list and the pane, the
 // web counterpart of the TUI's `ctrl-w h`. It has to be a chord: an attached
 // terminal owns every plain keystroke, so nothing unmodified could ever get
 // the focus back out of it.
+//
+// This set also owns the leader (`ctrl-a`, the TUI's default): it holds the
+// key as a partial chord and takes select-all off it, so the escape hatch
+// docs/COMMAND-BAR.md describes has somewhere to land (#149).
+const focusKeys = new CommandSet(
+  defineCommands({
+    "focus.toggle": () => {
+      if (sidebar.hasListFocus()) {
+        pool.focusTerminal();
+      } else {
+        drawer.open(); // no-op on desktop; on mobile the list is off-canvas
+        sidebar.focusList();
+      }
+    },
+  }),
+  { leader: DEFAULT_LEADER },
+);
+
 window.addEventListener("keydown", (e) => {
-  if (!e.ctrlKey || !e.shiftKey || e.altKey || e.metaKey) return;
-  if (e.key !== "H" && e.key !== "h") return;
-  e.preventDefault();
-  if (sidebar.hasListFocus()) {
-    pool.focusTerminal();
-  } else {
-    drawer.open(); // no-op on desktop; on mobile the list is off-canvas
-    sidebar.focusList();
-  }
+  if (focusKeys.handle(e)) return;
+  // The help overlay owns the keyboard while it is up.
+  if (isHelpOpen()) return;
+  spawnKeys.handle(e);
 });
 
 // Tab in the session list hands the keyboard to the pane; Escape in the pane

web/src/matcher.test.ts

@@ -0,0 +1,201 @@
+import { describe, expect, it } from "vitest";
+
+import {
+  matchAndRank,
+  type CommandCandidate,
+  type DirectoryCandidate,
+  type MatchCandidate,
+  type MatchResult,
+  type SessionCandidate,
+} from "./matcher.js";
+
+function session(
+  name: string,
+  directory?: string,
+  command?: string,
+  tool?: string,
+): SessionCandidate {
+  return { kind: "session", fields: { name, directory, command, tool } };
+}
+
+function command(label: string): CommandCandidate {
+  return { kind: "command", fields: { label } };
+}
+
+function directory(path: string): DirectoryCandidate {
+  return { kind: "directory", fields: { path } };
+}
+
+function label(result: MatchResult): string {
+  switch (result.candidate.kind) {
+    case "session":
+      return `session:${result.candidate.fields.name}`;
+    case "command":
+      return `command:${result.candidate.fields.label}`;
+    case "directory":
+      return `directory:${result.candidate.fields.path}`;
+  }
+}
+
+function positions(result: MatchResult): number[] {
+  return result.ranges.flatMap(([start, end]) =>
+    Array.from({ length: end - start }, (_, offset) => start + offset),
+  );
+}
+
+function expectResults(
+  query: string,
+  candidates: MatchCandidate[],
+  expected: Array<[label: string, score: number, field?: string, positions?: number[]]>,
+): void {
+  const results = matchAndRank(query, candidates);
+
+  expect(results.map((result) => [label(result), result.score])).toEqual(
+    expected.map(([candidateLabel, score]) => [candidateLabel, score]),
+  );
+  expect(results.map((result) => result.field)).toEqual(
+    expected.map(([, , field]) => field),
+  );
+  expect(results.map(positions)).toEqual(expected.map(([, , , matched]) => matched ?? []));
+}
+
+describe("matchAndRank fixtures", () => {
+  it("F1: an empty query keeps input order", () => {
+    expectResults(
+      "",
+      [
+        session("kill", "~/dev/api", "bash"),
+        session("killer-app", "~/dev/killer-app", "claude --resume", "claude"),
+        command("Kill selected session"),
+      ],
+      [
+        ["session:kill", 0],
+        ["session:killer-app", 0],
+        ["command:Kill selected session", 0],
+      ],
+    );
+  });
+
+  it("F2: an exact session name beats a prefix and kind breaks a tie", () => {
+    expectResults(
+      "kill",
+      [
+        session("kill", "~/dev/api", "bash"),
+        session("killer-app", "~/dev/killer-app", "claude --resume", "claude"),
+        command("Kill selected session"),
+      ],
+      [
+        ["session:kill", 178, "name", [0, 1, 2, 3]],
+        ["session:killer-app", 146, "name", [0, 1, 2, 3]],
+        ["command:Kill selected session", 146, "label", [0, 1, 2, 3]],
+      ],
+    );
+  });
+
+  it("F3: path segment boundaries beat mid-segment matches", () => {
+    expectResults(
+      "foo",
+      [directory("~/dev/foobar"), directory("~/src/myfoo"), directory("~/foo")],
+      [
+        ["directory:~/foo", 78, "path", [2, 3, 4]],
+        ["directory:~/dev/foobar", 74, "path", [6, 7, 8]],
+        ["directory:~/src/myfoo", 56, "path", [8, 9, 10]],
+      ],
+    );
+  });
+
+  it("F4: a query matching nothing returns no candidates", () => {
+    expectResults("zzz", [session("kill", "~/dev/api", "bash"), command("Kill selected session")], []);
+  });
+
+  it("F5: the highest-scoring embedding can differ from the greedy embedding", () => {
+    expectResults(
+      "mtu",
+      [session("maestro-tui"), session("maestro-daemon"), session("mtui-scratch")],
+      [
+        ["session:mtui-scratch", 122, "name", [0, 1, 2]],
+        ["session:maestro-tui", 91, "name", [0, 8, 9]],
+      ],
+    );
+  });
+
+  it("F6: a name beats a weighted directory match", () => {
+    expectResults(
+      "api",
+      [session("api", "~/dev/web", "bash"), session("worker", "~/dev/api", "bash")],
+      [
+        ["session:api", 154, "name", [0, 1, 2]],
+        ["session:worker", 50, "directory", [6, 7, 8]],
+      ],
+    );
+  });
+
+  it("F7: matching is case-insensitive and field length breaks a tie", () => {
+    expectResults(
+      "api",
+      [session("API-Gateway"), session("apiary")],
+      [
+        ["session:apiary", 122, "name", [0, 1, 2]],
+        ["session:API-Gateway", 122, "name", [0, 1, 2]],
+      ],
+    );
+  });
+
+  it("F8: the exact tool field beats the command field", () => {
+    expectResults(
+      "claude",
+      [session("nameless", "~/dev/x", "claude --resume", "claude"), session("clay", "~/dev/y", "bash")],
+      [["session:nameless", 186, "tool", [0, 1, 2, 3, 4, 5]]],
+    );
+  });
+
+  it("F9: a separator earns a word-boundary bonus", () => {
+    expectResults(
+      "ws",
+      [session("websearch"), session("web-search")],
+      [
+        ["session:web-search", 71, "name", [0, 4]],
+        ["session:websearch", 56, "name", [0, 3]],
+      ],
+    );
+  });
+
+  it("F10: command labels rank by boundary and initial gap", () => {
+    expectResults(
+      "se",
+      [command("Kill selected session"), command("Create a session"), command("Show help")],
+      [
+        ["command:Show help", 53, "label", [0, 6]],
+        ["command:Kill selected session", 51, "label", [5, 6]],
+        ["command:Create a session", 47, "label", [9, 10]],
+      ],
+    );
+  });
+
+  it("F11: directory matches separate on their initial gap", () => {
+    expectResults(
+      "dev",
+      [
+        session("api", "~/dev/api", "bash"),
+        session("notes", "~/documents/dev-notes", "nvim"),
+        session("scratch", "~/srv/devops", "bash"),
+      ],
+      [
+        ["session:api", 54, "directory", [2, 3, 4]],
+        ["session:scratch", 50, "directory", [6, 7, 8]],
+        ["session:notes", 44, "directory", [12, 13, 14]],
+      ],
+    );
+  });
+
+  it("F12: an exact field beats a prefix", () => {
+    expectResults(
+      "quit",
+      [command("Quit Maestro"), command("Quit")],
+      [
+        ["command:Quit", 178, "label", [0, 1, 2, 3]],
+        ["command:Quit Maestro", 146, "label", [0, 1, 2, 3]],
+      ],
+    );
+  });
+});

web/src/matcher.ts

@@ -0,0 +1,224 @@
+export type CandidateKind = "session" | "command" | "directory";
+
+export interface SessionCandidate {
+  kind: "session";
+  fields: {
+    name: string;
+    directory?: string;
+    command?: string;
+    tool?: string;
+  };
+}
+
+export interface CommandCandidate {
+  kind: "command";
+  fields: { label: string };
+}
+
+export interface DirectoryCandidate {
+  kind: "directory";
+  fields: { path: string };
+}
+
+export type MatchCandidate = SessionCandidate | CommandCandidate | DirectoryCandidate;
+export type MatchFieldName = "name" | "directory" | "command" | "tool" | "label" | "path";
+export type MatchRange = readonly [start: number, end: number];
+
+export interface MatchResult<C extends MatchCandidate = MatchCandidate> {
+  candidate: C;
+  score: number;
+  field: MatchFieldName | undefined;
+  ranges: MatchRange[];
+}
+
+interface Field {
+  name: MatchFieldName;
+  text: string;
+  weight: number;
+}
+
+interface Embedding {
+  score: number;
+  positions: number[];
+}
+
+interface RankedResult<C extends MatchCandidate> extends MatchResult<C> {
+  matchedText: string;
+  inputIndex: number;
+}
+
+const KIND_ORDER: Record<CandidateKind, number> = {
+  session: 0,
+  command: 1,
+  directory: 2,
+};
+
+function fields(candidate: MatchCandidate): Field[] {
+  switch (candidate.kind) {
+    case "session": {
+      const values: Array<[MatchFieldName, string | undefined, number]> = [
+        ["name", candidate.fields.name, 0],
+        ["directory", candidate.fields.directory, -24],
+        ["command", candidate.fields.command, -32],
+        ["tool", candidate.fields.tool, -40],
+      ];
+      return values.flatMap(([name, text, weight]) =>
+        text === undefined ? [] : [{ name, text, weight }],
+      );
+    }
+    case "command":
+      return [{ name: "label", text: candidate.fields.label, weight: 0 }];
+    case "directory":
+      return [{ name: "path", text: candidate.fields.path, weight: 0 }];
+  }
+}
+
+function normalizeQuery(query: string): string {
+  return query.toLowerCase().replace(/\s/g, "");
+}
+
+function boundaryBonus(text: string, position: number): number {
+  if (position === 0) return 18;
+
+  const previous = text[position - 1];
+  if ("/\\-_ .:".includes(previous)) return 16;
+
+  const current = text[position];
+  const isUppercase = current !== current.toLowerCase() && current === current.toUpperCase();
+  const previousIsLowercase =
+    previous !== previous.toUpperCase() && previous === previous.toLowerCase();
+  if (isUppercase && previousIsLowercase) return 12;
+
+  const isDigit = current >= "0" && current <= "9";
+  const previousIsDigit = previous >= "0" && previous <= "9";
+  if (isDigit && !previousIsDigit) return 12;
+
+  return 0;
+}
+
+function contribution(text: string, position: number, previousPosition: number): number {
+  const gap = position - previousPosition - 1;
+  return 16 + boundaryBonus(text, position) + (gap === 0 ? 8 : -Math.min(gap, 12));
+}
+
+function isBetterEmbedding(candidate: Embedding, incumbent: Embedding | undefined): boolean {
+  if (!incumbent || candidate.score !== incumbent.score) {
+    return !incumbent || candidate.score > incumbent.score;
+  }
+  for (let index = 0; index < candidate.positions.length; index++) {
+    if (candidate.positions[index] !== incumbent.positions[index]) {
+      return candidate.positions[index] < incumbent.positions[index];
+    }
+  }
+  return false;
+}
+
+function bestEmbedding(query: string, text: string): Embedding | undefined {
+  const lowerText = text.toLowerCase();
+  let previousStates = new Map<number, Embedding>();
+
+  for (let queryIndex = 0; queryIndex < query.length; queryIndex++) {
+    const states = new Map<number, Embedding>();
+    for (let position = 0; position < lowerText.length; position++) {
+      if (lowerText[position] !== query[queryIndex]) continue;
+
+      if (queryIndex === 0) {
+        states.set(position, {
+          score: contribution(text, position, -1),
+          positions: [position],
+        });
+        continue;
+      }
+
+      for (const [previousPosition, previous] of previousStates) {
+        if (previousPosition >= position) continue;
+        const candidate = {
+          score: previous.score + contribution(text, position, previousPosition),
+          positions: [...previous.positions, position],
+        };
+        if (isBetterEmbedding(candidate, states.get(position))) states.set(position, candidate);
+      }
+    }
+    if (states.size === 0) return undefined;
+    previousStates = states;
+  }
+
+  let best: Embedding | undefined;
+  for (const embedding of previousStates.values()) {
+    if (isBetterEmbedding(embedding, best)) best = embedding;
+  }
+  return best;
+}
+
+function toRanges(positions: number[]): MatchRange[] {
+  const ranges: MatchRange[] = [];
+  for (const position of positions) {
+    const previous = ranges[ranges.length - 1];
+    if (previous && previous[1] === position) {
+      ranges[ranges.length - 1] = [previous[0], position + 1];
+    } else {
+      ranges.push([position, position + 1]);
+    }
+  }
+  return ranges;
+}
+
+function compareByCodePoint(left: string, right: string): number {
+  const leftPoints = Array.from(left, (character) => character.codePointAt(0)!);
+  const rightPoints = Array.from(right, (character) => character.codePointAt(0)!);
+  const length = Math.min(leftPoints.length, rightPoints.length);
+  for (let index = 0; index < length; index++) {
+    if (leftPoints[index] !== rightPoints[index]) return leftPoints[index] - rightPoints[index];
+  }
+  return leftPoints.length - rightPoints.length;
+}
+
+export function matchAndRank<C extends MatchCandidate>(
+  query: string,
+  candidates: readonly C[],
+): MatchResult<C>[] {
+  const normalizedQuery = normalizeQuery(query);
+  if (normalizedQuery === "") {
+    return candidates.map((candidate) => ({ candidate, score: 0, field: undefined, ranges: [] }));
+  }
+
+  const results: RankedResult<C>[] = [];
+  candidates.forEach((candidate, inputIndex) => {
+    let best:
+      | { field: Field; score: number; positions: number[] }
+      | undefined;
+
+    for (const field of fields(candidate)) {
+      const embedding = bestEmbedding(normalizedQuery, field.text);
+      if (!embedding) continue;
+
+      const compactText = field.text.toLowerCase().replace(/\s/g, "");
+      const adjustment =
+        compactText === normalizedQuery ? 64 : compactText.startsWith(normalizedQuery) ? 32 : 0;
+      const score = embedding.score + adjustment + field.weight;
+      if (!best || score > best.score) best = { field, score, positions: embedding.positions };
+    }
+
+    if (best) {
+      results.push({
+        candidate,
+        score: best.score,
+        field: best.field.name,
+        ranges: toRanges(best.positions),
+        matchedText: best.field.text,
+        inputIndex,
+      });
+    }
+  });
+
+  results.sort(
+    (left, right) =>
+      right.score - left.score ||
+      KIND_ORDER[left.candidate.kind] - KIND_ORDER[right.candidate.kind] ||
+      left.matchedText.length - right.matchedText.length ||
+      compareByCodePoint(left.matchedText, right.matchedText) ||
+      left.inputIndex - right.inputIndex,
+  );
+
+  return results.map(({ candidate, score, field, ranges }) => ({ candidate, score, field, ranges }));
+}

web/src/types.ts

@@ -50,6 +50,12 @@ export interface Session {
    * create one. `base_repo` is the repository's main checkout, which is what
    * the session tree groups by (#99). */
   worktree?: SessionWorktree | null;
+  /** Wall-clock of when this session last became the pane a client was showing
+   * (#145) — stamped by both `POST /api/sessions/:id/focus` and opening
+   * `/api/attach/:id`. Absent until the session has been focused once, which is
+   * how the command bar's empty query sorts a never-focused session after every
+   * session that has one (`docs/COMMAND-BAR.md`). */
+  last_focused_at?: IsoTimestamp | null;
 }
 
 /** A session's daemon-created worktree (`SessionWorktree` on the wire). */