Research: how should DropTerm V3 build a COSMIC panel applet that toggles the terminal and shows status?

Date: 2026-10-03 Question: What does the COSMIC panel applet platform actually provide, how do first- and third-party applets structure themselves and talk to other processes, what is the industry precedent in quake-style terminals, and which parts should DropTerm adopt?

TL;DR

Ship a separate applet binary (cosmic-ext-dropterm-applet) from the same crate, and give the main app one small custom D-Bus interface on the bus name it already owns. The panel platform is mature and fully documented by source: applets are ordinary processes discovered by desktop-file stem, launched with a Wayland socket fd pointing at the panel, sized via COSMIC_PANEL_SIZE env + PanelSize helpers in libcosmic — and libcosmic at DropTerm’s pinned rev 08a09e3 ships the complete cosmic::applet module (Context, popup helpers, cosmic::applet::run, byte-identical on master as of 2026-10-02). The single-instance seam DropTerm already uses exposes org.freedesktop.DbusActivation with fire-and-forget methods and no properties or signals — which is exactly why --is-visible is stuck — but libcosmic provides a sanctioned hook (ApplicationExt::dbus_connection) documented as “Can be used to expose custom interfaces on the same owned name”. Add Toggle/Show/Hide methods plus a read-only Visible property (PropertiesChanged for free) there; the applet watches the bus name via NameOwnerChanged (the pattern cosmic-applet-status-area and the third-party now-playing applet both use) to switch between live status and a “launch” state. Left-click toggles — the unanimous quake precedent (Yakuake and Guake both default their tray icon on, wired to toggle). Note the honest alternative: a system tray does exist on COSMIC (cosmic-applet-status-area implements the full KDE StatusNotifierWatcher, installed in the default panel config), so an SNI item is a viable smaller sibling — but it cannot show COSMIC-native status styling and is second choice for the ROADMAP item as written.

Findings

1. cosmic-panel: applets are processes discovered by desktop-file stem

From pop-os/cosmic-panel @ master (f4ba4ef, 2026-10-01, cloned 2026-10-03):

• The panel’s config (CosmicPanelContainerConfig) stores applet lists as desktop-file IDs (file stems) in plugins_wings / plugins_center — cosmic-panel-config/src/container_config.rs L145-163 (defaults: workspaces/app button left; status area, tiling, audio, bluetooth, network, battery, notifications, power right; time center) and L191-197 (dock defaults).
• spawn_clients (cosmic-panel-bin/src/space/wrapper_space.rs L375-519) resolves each ID by iterating freedesktop_desktop_entry::default_paths() and matching path.file_stem() == name — “each applet is at most started once, even if multiple desktop files in different directories match” (comment at L463-464). No X-CosmicApplet key is consulted at spawn time; the stem is the identity.
• Each applet is spawned with (Process::new() from cosmic-process-manager, L637-660):
  • WAYLAND_SOCKET = an fd to the panel’s own Wayland display (L601) — the panel acts as a nested compositor host (xdg-shell-wrapper); applet surfaces render inside the panel.
  • env COSMIC_PANEL_NAME, COSMIC_PANEL_OUTPUT, COSMIC_PANEL_SPACING, COSMIC_PANEL_ANCHOR, COSMIC_PANEL_BACKGROUND, COSMIC_PANEL_PADDING_OVERLAP (RON-serialized, L440-453) and COSMIC_PANEL_SIZE = the effective size for that slot’s side (L562-565), so a per-side size_wings/size_center override in panel config reaches the applet transparently.
  • optionally X_PRIVILEGED_WAYLAND_SOCKET — a security-context listener fd (wayland-security-context protocol) when the desktop file sets X-HostWaylandDisplay (L480, L566-593); app-set sandbox metadata is app_id = the applet name, instance_id = name.output (L571-576).
  • Flatpak applets get --die-with-parent, --socket=inherit-wayland-socket, and --env= arg forwarding (L622-631).
• Lifecycle: applets that die abnormally are respawned with a fresh socket — with_on_exit closure with should_restart = is_restarting && err_code.is_some() (L661-681, restart path L716-779). The client side of the contract: an applet exits when its panel connection breaks — libcosmic’s token handler logs “Connection to panel has ended. The applet will now exit with it.” and breaks the loop (libcosmic src/applet/token/wayland_handler.rs L168-174).
• Adding an applet at runtime needs no panel API: cosmic-settings writes the panel config; the panel watches it via cosmic-config watchers and rebuilds — cosmic-panel-bin/src/config_watching.rs L100-194 (ConfigUpdate::Entries → update_space, entry watchers → ConfigUpdate::EntryChanged).

2. The desktop-file contract: exact keys and the sizing mechanism

Verified from cosmic-panel wrapper_space.rs L473-514 (all keys the panel reads) and the shipped desktop files in pop-os/cosmic-applets @ master (57ace74, 2026-09-30, cloned 2026-10-03):

Real example — cosmic-applet-audio/data/com.system76.CosmicAppletAudio.desktop: X-CosmicApplet=true, X-CosmicShrinkable=true, X-CosmicHoverPopup=End, X-OverflowPriority=10, NoDisplay=true, Icon=...-symbolic, StartupNotify=true.

Sizing: there is no X-CosmicApplet-Size key. Size hints flow at runtime: panel → COSMIC_PANEL_SIZE (RON PanelSize) → libcosmic applet::Context → PanelSize::get_applet_icon_size/padding/shrinkable_padding (cosmic-panel-config/src/panel_config.rs L143-227). Concrete numbers: symbolic icon sizes XS=16, S=20, M=28, L=32, XL=48 (Custom s/2); symbolic padding 8/10/14/16/16; shrinkable padding 12/14/18/20/20. Applets call core.applet.suggested_size(true) and never hardcode pixels — that is the entire size-hint mechanism.

3. libcosmic applet support at DropTerm’s pinned rev

Verified in the local checkout of [pop-os/libcosmic @ 08a09e3] (https://github.com/pop-os/libcosmic/tree/08a09e3dfa1f729d52585fcedd6e731130235363) (DropTerm pins this rev — Cargo.toml):

• cosmic::applet module (src/applet/mod.rs), enabled by the applet feature (Cargo.toml L36-44: autosize, winit, wayland, tokio, cosmic-panel-config, ron, multi-window; applet-token = ["applet"] at L45):
  • applet::Context (core.applet, always present on app::Core — src/core.rs L102) populated from the panel’s env vars in Default (mod.rs L89-119).
  • suggested_size / suggested_padding / suggested_window_size (L122-171), window_settings() (L178-202: transparent, non-resizable, correct min size), theme() honoring COSMIC_PANEL_BACKGROUND Dark/Light override (L488-503), text style scaling with panel size (L505-528).
  • Widget helpers: icon_button(name) (L280-291), text_button (L253-278), applet_tooltip (L293-356, a Wayland subsurface tooltip anchored per panel edge), popup_container (L358-402, rounded 360px-max autosize popup chrome), and get_popup_settings(parent, id, …) (L404-457) producing the SctkPopupSettings with anchor/gravity flipped per panel edge — the standard way applet popups are made.
  • menu_button / padded_control / menu_control_padding (L605-626) for popup menu rows, and applet::style() (L595-603) returning a transparent-background style.
  • cosmic::applet::run::<App>(flags) (L536-593): runs the app as an iced daemon with AppType::Applet, no decorations, exit_on_close_request = true. There is no separate cosmic::applet::App trait at this rev — applets implement the ordinary cosmic::Application.
  • cosmic::applet::token::activation_token_subscription (behind applet-token, src/applet/token/subscription.rs L13-25): a subscription that lets an applet request an xdg-activation token for an app it wants to launch (TokenRequest { app_id, exec } → TokenUpdate::ActivationToken { token, exec }), connecting either via the privileged socket or WAYLAND_DISPLAY.
• Stability check: cloned libcosmic master (5a8bd94, 2026-10-02) and diffed — src/applet/mod.rs public surface and src/dbus_activation.rs are byte-identical to the pinned rev. The applet API DropTerm would build on has not drifted.

4. Canonical applet anatomy and the IPC patterns applets use

From pop-os/cosmic-applets @ 57ace74:

• Simple applet — time (cosmic-applet-time/): crate with src/main.rs (init logging) → lib.rs run() → cosmic::applet::run::<Window>(()); the app type implements cosmic::Application with its own APP_ID (src/window.rs L317-321), style() = Some(cosmic::applet::style()) (L359-361). Left-click toggles a popup: Message::TogglePopup → cosmic::surface::action::app_popup
  • core.applet.get_popup_settings(main_window_id, new_id, …) with the applet’s tracked rectangle as anchor (L519-557); popup content is core.applet.popup_container(...) in view_window (L760-763), ending with the settings menu_button item. Cargo.toml: libcosmic + zbus + timedate-zbus (system bus TimeDateProxy, receive_timezone_changed, L436-454) + logind-zbus (receive_prepare_for_sleep, L478-489) + core.watch_config(APP_ID) — i.e. plain zbus proxies inside iced subscriptions is the accepted way applets consume D-Bus.
• Launching another app (the pattern DropTerm’s applet needs for “not running → start”): the time applet’s “Date & Time Settings…” item sends a TokenRequest (window.rs L607-618), and on TokenUpdate::ActivationToken spawns std::process::Command::new("cosmic-settings").arg("time") with XDG_ACTIVATION_TOKEN and DESKTOP_STARTUP_ID env set from the token, via tokio::spawn(cosmic::process::spawn(cmd)) (L627-635). The power applet does the simpler fire-and-forget variant: process::Command::new("cosmic-osd").arg("log-out").spawn() (cosmic-applet-power/src/lib.rs L159-171) and cosmic-settings (L196-201).
• Applet ↔ daemon over D-Bus: the notifications applet talks to a separate daemon over a peer-to-peer zbus connection on a Unix socket fd passed as COSMIC_NOTIFICATIONS (src/subscriptions/notifications.rs L134-169 — custom interface com.system76.NotificationsApplet with notify signal + invoke_action), and when the daemon is unreachable it retries 5× and then exits, relying on the panel’s respawn (L60-80, comment: “the applet needs the notifications daemon in order to work properly”). The audio applet instead uses zlink (Pulse/PipeWire wire protocol) + mpris2-zbus (Cargo.toml), and the tiling applet drives cosmic-comp over custom Wayland protocols (cosmic-applet-tiling/src/wayland.rs L4-40, ext_workspace + cosmic_protocols workspace-v2 TilingState). Pattern summary: whatever transport the service speaks, the applet hosts a subscription and renders state; D-Bus proxies are the default.

5. A system tray exists on COSMIC (2026 state)

cosmic-applet-status-area in pop-os/cosmic-applets @ 57ace74 implements the full KDE StatusNotifierItem host stack:

• A socket-activated daemon owns org.kde.StatusNotifierWatcher at /StatusNotifierWatcher with RegisterStatusNotifierItem, RegisteredStatusNotifierItems/IsStatusNotifierHostRegistered/ProtocolVersion properties and the four standard signals (src/subscriptions/status_notifier_watcher/server.rs L17-85). It is split into a separate com.system76.CosmicStatusNotifierWatcher daemon so panel restarts don’t race to re-own the name (src/status_notifier_watcher.rs L1-51).
• Hosts watch org.freedesktop.DBus.NameOwnerChanged to reap items whose owners vanished (server.rs L98-110; src/unique_names.rs L1-114, which cites pop-os/cosmic-comp/src/dbus/name_owners.rs as its model — cosmic-comp itself uses the same watching pattern for its D-Bus clients).
• Items are consumed as SNI clients (Status, IconName/IconPixmap, Menu via DBusMenu, Activate/SecondaryActivate, ItemIsMenu — src/subscriptions/status_notifier_item.rs L13-167).
• The status area ships in the default panel config (cosmic-panel/.../container_config.rs L153), so every stock COSMIC install renders tray icons. Third parties also ship SNI hosts (marcelogomes90/cosmic-ext-applet-status-hub, listed in the cosmic-utils collection). A Rust app can publish an SNI item with the maintained ksni crate (iovxw/ksni, Unlicense — GPL-compatible; pushed 2026-09-30).

So SNI is not missing; it is simply not the native panel surface. A panel applet remains the only route with COSMIC-native theming, sizing, and popup behavior — but a tray icon is a legitimate low-effort complement.

6. libcosmic single-instance D-Bus API — exact surface and the sanctioned extension hook

Verified at the pinned rev 08a09e3 (byte-identical on master 5a8bd94):

• Server side (src/dbus_activation.rs): session bus; bus name = App::APP_ID (requested after object_server().at(), L37-44); object path = / + APP_ID with . → / (L24); interface org.freedesktop.DbusActivation with exactly three methods: activate(platform_data), open(uris, platform_data), activate_action(action_name, parameter: Vec<&str>, platform_data) (proxy trait L131-150, impl L152-229). No properties. No signals. activate_action’s action string is documented as “can be deserialized as Flags” (L106-107) — this is the seam DropTerm’s toggle/show/hide/new-tab CLI already rides.
• Client side (src/app/mod.rs L189-257, run_single_instance): on launch, a blocking proxy to destination = APP_ID, same path/interface; if the proxy call succeeds the second process exits immediately — the caller learns only success/failure of a fire-and-forget call, nothing about state (L243-256). XDG_ACTIVATION_TOKEN and DESKTOP_STARTUP_ID env are forwarded as activation-token/desktop-startup-id platform data (L205, L229-235). COSMIC_SINGLE_INSTANCE=false disables the forwarding (L207-212).
• The extension hook: when the single-instance subscription connects, it delivers the live zbus::Connection to the app as Action::Cosmic(Action::DbusConnection(conn)) (dbus_activation.rs L46-50), dispatched to ApplicationExt::dbus_connection(&mut self, conn) (src/app/cosmic.rs L1250-1253), whose doc reads verbatim: “Invoked on connect to dbus session socket used for dbus activation. Can be used to expose custom interfaces on the same owned name.” (src/app/mod.rs L506-512). zbus object paths can host multiple interfaces, so a custom DropTerm interface can live at the same path as org.freedesktop.DbusActivation without touching libcosmic.

Conclusion for the ROADMAP’s deferred note: correct — nothing queryable exists today; a custom interface is required, and it is explicitly supported.

7. Third-party applets: structure and cross-process control

The ecosystem hub is cosmic-utils (org + project collection, fetched 2026-10-03; ~50 applets listed). Verified examples, cloned 2026-10-03:

• Hasmolam/cosmic-ext-applet-scratchpad @ master (2026-09-28): the canonical modern third-party shape — standalone crate, GPL-3.0-only, cosmic::applet::run, libcosmic pinned by rev with features applet, applet-token, dbus-config, multi-window, tokio, wayland, … (deliberately without wgpu), desktop file with X-CosmicApplet=true + NoDisplay=true, own -symbolic icon, install.sh/justfile.
• cosmic-utils/cosmic-ext-applet-now-playing @ master (2026-09-01) — applet reflecting a separate service that may vanish: it subscribes to MPRIS players and adds a raw MatchRule for org.freedesktop.DBus.NameOwnerChanged, filtering names starting with org.mpris.MediaPlayer2. (src/media.rs L189-202, L239-241) to re-enumerate players when one appears/quits; with no player it renders a placeholder icon (src/ui.rs L123-131, fallback audio-x-generic-symbolic).
• glima/mare-player @ master (2026-10-02) — one codebase, two faces: a panel-applet cargo feature (default) selects libcosmic/applet + applet-token; disabling it builds a standalone windowed app (Cargo.toml L22-32). Its Cargo.toml also documents a real pitfall DropTerm should copy the conclusion of: wgpu on a layer-shell applet surface fails to bind the GPU and falls back to llvmpipe (~350 MB of software GL), so the applet build uses tiny_skia only (comment block L33-40). A companion video-window helper lives as a second workspace member binary talking over a stdin/stdout pipe.

No third-party applet was found that embeds its target app’s UI — cross-process control is always D-Bus/launch. That matches the platform’s shape: an applet is its own libcosmic process.

8. Quake-terminal precedent: tray icons are the norm

• Yakuake (KDE/yakuake @ master, 2026-09-26): ships a KStatusNotifierItem — app/mainwindow.cpp L938-950: icon yakuake-symbolic, setStatus(Active), context menu = the main window menu, and — the load-bearing lines — setAssociatedWindow(nullptr) “Prevent the default implementation of showing and instead run toggleWindowState” followed by connect(m_notifierItem, &KStatusNotifierItem::activateRequested, this, &MainWindow::toggleWindowState) (L947-948). Left-click on the tray toggles the drop-down. The tray icon is on by default: ShowSystrayIcon <default>true</default> (app/config/yakuake.kcfg L74-78).
• Guake (Guake/guake @ master, 2026-08-19): tray icon on by default (use-trayicon <default>true</default>, guake/data/org.guake.gschema.xml L59-62). Left-click activate → show_hide (toggle); the fallback Gtk.StatusIcon path is identical (guake/guake_app.py L163-182). The AppIndicator path serves the same “Show” menu.
• Tilda (lanoxx/tilda @ master, 2026-01-10): no tray icon — its answer is D-Bus: interface com.github.lanoxx.tilda.Actions at /com/github/lanoxx/tilda/Actions with a single Toggle method (src/tilda-dbus-actions.xml, bus name in src/tilda-dbus-actions.c L6), which the CLI invokes (tilda -T → tilda_dbus_actions_toggle, src/tilda.c L256); instance IDs are appended to the bus name for multi-instance (tilda-dbus-actions.c L140).
• QTerminal (lxqt/qterminal @ master, 2026-09-29): no tray icon anywhere in src/ (grep for tray/TrayIcon: zero hits); its drop-down mode is layer-shell native (src/mainwindow.cpp L193 m_layerWindow->setScope(QStringLiteral("dropdown_terminal"))), toggled by hotkey only — the closest architectural sibling to DropTerm, and it has neither tray nor applet today.
• iTerm2 (gnachman/iTerm2 @ master, 2026-09-30): the hotkey window is toggled by global hotkey only. A menu-bar NSStatusItem exists but is not a toggle: it appears only when the app is excluded from the Dock, guarded by advanced setting statusBarIcon (default YES, sources/AppKit/iTermApplication.m L965-988), and shows a menu of Settings / Bring All Windows to Front / Buried Sessions / Check For Updates (sources/AppKit/iTermApplicationDelegate.m L1853-1877). Official docs match: the Appearance page describes the menu-bar icon as a way “to get back to iTerm2’s preferences… useful if you only use hotkey windows”.

9. GNOME ddterm: the shell-extension contrast, and the D-Bus shape DropTerm needs

ddterm/gnome-shell-extension-ddterm @ master (2026-10-01) is the maintained GNOME drop-down terminal: the GNOME Shell itself hosts the UI (JavaScript extension + a VTE app process), and control is exposed three ways (docs/CommandLine.md): a CLI tool, gapplication action … show/hide/toggle, and a dedicated D-Bus interface. The last one is the blueprint — data/com.github.amezin.ddterm.Extension.xml:

• methods Toggle, Activate, Hide, Service;
• read-only properties HasWindow (b), TargetRect (iiii), TargetMonitorScale (d), Version, Revision — with PropertiesChanged emitted on change (ddterm/shell/dbusapi.js L133-163, emit_property_changed('HasWindow', …) L310), exported at /org/gnome/Shell/Extensions/ddterm on the session bus.

The contrast DropTerm must respect: COSMIC has no shell extensions — the sanctioned equivalent of “integrate with the shell chrome” is a panel applet (finding 1-3), and the sanctioned equivalent of the extension’s queryable control interface is a custom interface on the app’s owned bus name (finding 6). ddterm shows both halves done well.

What applies to DropTerm

Recommended architecture

1. Same crate, second [[bin]]: cosmic-ext-dropterm-applet. Precedent: pop-os keeps every applet a separate crate in a workspace; third parties ship standalone crates; mare-player proves dual-targeting one codebase is fine — but via a compile-time feature, which cannot run app and applet concurrently. DropTerm needs both alive at once (app owns the layer surface; applet lives in the panel), so two process entry points are required. A cosmic-ext-dropterm applet subcommand would also work (the panel Shlex-splits Exec=cosmic-ext-dropterm applet), but it drags applet mode into the user-facing clap CLI whose default subcommand is toggle; a dedicated bin target is cleaner, matches the stem-matching identity scheme, and keeps logs unambiguous. The applet bin gets its own APP_ID (io.github.l1br3_io.CosmicExtDropterm.Applet), its own desktop file, and calls cosmic::applet::run — never run_single_instance, which would just forward-activate the terminal and exit, leaving a blank panel slot.
2. Control channel: keep activate_action for commands, add one tiny custom interface for state. Toggle/show/hide/new-tab already ride org.freedesktop.DbusActivation.activate_action — the applet reuses them verbatim (same messages the CLI produces, so one code path). For status, implement in the app:
   • bus name io.github.l1br3_io.CosmicExtDropterm (already owned),
   • path /io/github/l1br3_io/CosmicExtDropterm (same object as the activation interface),
   • interface e.g. io.github.l1br3_io.CosmicExtDropterm.V1 served from the ApplicationExt::dbus_connection hook (zbus #[interface]; object_server().at() on the handed-over connection),
   • methods Toggle(), Show(), Hide(), NewTab(cwd, cmd) (mirroring the CLI — convenient for non-libcosmic callers; optional if activate_action suffices),
   • read-only properties Visible: bool, TabCount: u32, BellPending: bool — zbus emits PropertiesChanged automatically when properties mutate, which is the VisibilityChanged signal the ROADMAP sketched, for free. Effort S-M: zbus 5 is already in the tree; the hook exists; it’s one file plus property updates on show/hide/tab/bell transitions.
3. --is-visible unblocks for free: read Visible off the proxy; if the bus name has no owner, the app isn’t running → print false / exit non-zero. Effort S.
4. Applet runtime state: subscribe to NameOwnerChanged filtered on io.github.l1br3_io.CosmicExtDropterm (status-area unique_names.rs / now-playing media.rs pattern, both zbus 5). Not running → dimmed button, click spawns the CLI binary with an activation token obtained via applet-token (time-applet pattern) so the summoned terminal is properly activated. Running → reflect Visible; left-click calls Toggle. Optional popup (popup_container) with New Tab / Settings / Quit, right-click or a small popup button — but keep V1 minimal: an icon button that toggles, a tooltip, done.
5. Desktop file for the applet (keys from finding 2): Exec=cosmic-ext-dropterm-applet, X-CosmicApplet=true, NoDisplay=true, Icon=io.github.l1br3_io.CosmicExtDropterm-symbolic (ship a symbolic SVG to icons/hicolor/scalable/apps/; a generic fallback exists — utilities-terminal-symbolic is in Pop’s theme, Pop/scalable/apps/, verified in the pop-os/icon-theme tree 2026-10-03). Skip X-HostWaylandDisplay (DropTerm needs no privileged socket), set X-CosmicShrinkable=true. Install desktop file to share/applications, icon to share/icons/hicolor/... (cosmic-applets justfile L37-51 pattern). Effort S.
6. Applet build config: enable libcosmic applet + applet-token features for the applet bin only. Do not enable wgpu for the applet (mare-player’s documented llvmpipe fallback on layer-shell surfaces); tiny_skia is what stock applets use. Effort M overall for the applet UI (Context-driven sizing, popup, tooltip, state machine, tests for the pure logic).
7. Licensing/packaging: everything verified compatible — libcosmic MPL-2.0, ksni Unlicense, applets typically GPL-3.0-only like DropTerm. No new copyleft obligations.

Status content worth showing in a ~20-32px slot: running/not (dim), visible/hidden (the Yakuake/Guake tray parity), tab count as a small badge or in the tooltip, and bell/attention state if the existing notification path exposes it — the now-playing applet proves text+icon is possible, but V1 should be icon + tooltip (applet_tooltip) with the popup carrying anything richer. Visible and running-state are the two with primary-source precedent (ddterm HasWindow; Yakuake tooltip).

Risks / open questions

• Pinned-rev API stability: verified non-issue today (applet module and dbus_activation byte-identical between 08a09e3 and master 5a8bd94), but the applet module carries // TODO make multi-window not mandatory and the sizing helpers have changed historically — keep the applet thin and re-diff on any libcosmic bump.
• Panel-side hover-popup semantics: X-CosmicHoverPopup values (Auto, End) are anchors for a panel-initiated hover popup; the exact UX (hover-show of the applet’s popup) is inferred from panel_space.rs L150-160 + auto_popup_hover_press naming — not traced end-to-end. Skip the key in V1; nothing depends on it.
• Respawn semantics: the restart condition is is_restarting && err_code.is_some() (wrapper_space.rs L681); the exact meaning of err_code/is_restarting in cosmic-process-manager was not read — whether a clean exit(0) triggers respawn (the notifications applet seems to rely on it) is unverified. DropTerm’s applet shouldn’t depend on either behavior; exit only when the panel connection dies.
• Token forwarding value (resolved on review): run_single_instance forwards XDG_ACTIVATION_TOKEN as platform data (verified, src/app/mod.rs L205-231) and the server side unpacks it into the activation Message struct (src/dbus_activation.rs L155-229) — but at the pinned rev nothing in libcosmic applies it, and DropTerm’s src/ never references it (grep: zero hits). The token is currently delivered and dropped. Harmless today — the shown layer surface takes exclusive keyboard focus on its own, so it never needed an xdg-activation raise — and it means the applet’s launch-with-token path (finding 4) gains nothing until DropTerm starts consuming the token; the time-applet pattern is still the correct one to copy when it does.
• Flatpak: if DropTerm ever ships as a flatpak applet, the panel’s flatpak arg injection (wrapper_space.rs L622-631) applies — the cosmic-flatpak issue #259 (an applet removed because it “can’t work inside the Flatpak sandbox”) is a warning to test D-Bus + process spawning under sandboxing before promising it.

Sources

• cosmic-panel @ master f4ba4ef (cloned 2026-10-03): cosmic-panel-bin/src/space/wrapper_space.rs L375-519, L528-603, L622-631, L637-779; cosmic-panel-bin/src/config_watching.rs L100-194; cosmic-panel-bin/src/space/panel_space.rs L150-160; cosmic-panel-config/src/container_config.rs L131-216; cosmic-panel-config/src/panel_config.rs L126-227 — https://github.com/pop-os/cosmic-panel
• cosmic-applets @ master 57ace74 (cloned 2026-10-03): cosmic-applet-time/src/window.rs L317-321, L359-361, L436-489, L519-557, L607-637; cosmic-applet-time/src/lib.rs; cosmic-applet-time/data/com.system76.CosmicAppletTime.desktop; cosmic-applet-audio/data/com.system76.CosmicAppletAudio.desktop; cosmic-applet-power/src/lib.rs L159-201; cosmic-applet-notifications/src/subscriptions/notifications.rs L60-80, L134-169; cosmic-applet-status-area/src/status_notifier_watcher.rs L1-51, src/subscriptions/status_notifier_watcher/server.rs L17-110, src/unique_names.rs L1-114, src/subscriptions/status_notifier_item.rs L13-167; cosmic-applet-tiling/src/wayland.rs L4-40; workspace Cargo.toml L57 (zbus 5.14); justfile L37-51 — https://github.com/pop-os/cosmic-applets
• cosmic-settings @ master (cloned 2026-10-03): cosmic-settings/src/pages/desktop/panel/applets_inner.rs L540-583; cosmic-settings/src/pages/applications/startup_apps.rs L498 — https://github.com/pop-os/cosmic-settings
• libcosmic @ 08a09e3 (DropTerm’s pinned rev, local cargo checkout): src/applet/mod.rs (entire module; run at L536-593, Context L42-119, helpers L122-528); src/applet/token/subscription.rs L13-80; src/applet/token/wayland_handler.rs L93-184; src/dbus_activation.rs L1-229; src/app/mod.rs L189-257, L506-512; src/app/cosmic.rs L1250-1253; src/core.rs L102; Cargo.toml L36-45, L72 — https://github.com/pop-os/libcosmic/tree/08a09e3dfa1f729d52585fcedd6e731130235363
• libcosmic @ master 5a8bd94 (2026-10-02, cloned 2026-10-03): diff vs pinned rev of src/applet/mod.rs and src/dbus_activation.rs — identical — https://github.com/pop-os/libcosmic
• cosmic-applet-template README (fetched 2026-10-03): https://github.com/pop-os/cosmic-applet-template
• cosmic-utils project collection README (fetched 2026-10-03): https://github.com/cosmic-utils/cosmic-project-collection
• Hasmolam/cosmic-ext-applet-scratchpad @ master (2026-09-28, cloned 2026-10-03): Cargo.toml, data/…desktop — https://github.com/Hasmolam/cosmic-ext-applet-scratchpad
• cosmic-utils/cosmic-ext-applet-now-playing @ master (2026-09-01, cloned 2026-10-03): src/media.rs L22-24, L189-241; src/ui.rs L95-138; desktop file — https://github.com/cosmic-utils/cosmic-ext-applet-now-playing
• glima/mare-player @ master (2026-10-02, cloned 2026-10-03): Cargo.toml L1-40, L130-175 — https://github.com/glima/mare-player
• Yakuake @ master (2026-09-26, cloned 2026-10-03): app/mainwindow.cpp L938-950; app/config/yakuake.kcfg L74-78 — https://github.com/KDE/yakuake
• Guake @ master (2026-08-19, cloned 2026-10-03): guake/guake_app.py L148-182; guake/data/org.guake.gschema.xml L59-62 — https://github.com/Guake/guake
• Tilda @ master (2026-01-10, cloned 2026-10-03): src/tilda-dbus-actions.xml; src/tilda-dbus-actions.c L3-30, L90-113; src/tilda.c L256, L330-351 — https://github.com/lanoxx/tilda
• QTerminal @ master (2026-09-29, cloned 2026-10-03): zero tray hits in src/; src/mainwindow.cpp L193 — https://github.com/lxqt/qterminal
• iTerm2 @ master (2026-09-30, cloned 2026-10-03): sources/AppKit/iTermApplication.m L965-993; sources/AppKit/iTermApplicationDelegate.m L1853-1877; sources/Settings/iTermAdvancedSettingsModel.m L508; docs https://iterm2.com/3.4/documentation-preferences-appearance.html — https://github.com/gnachman/iTerm2
• ddterm @ master (2026-10-01, cloned 2026-10-03): README.md; docs/CommandLine.md; data/com.github.amezin.ddterm.Extension.xml; ddterm/shell/dbusapi.js L55-110, L133-188, L282-310 — https://github.com/ddterm/gnome-shell-extension-ddterm
• ksni (API check 2026-10-03): https://github.com/iovxw/ksni — Unlicense, active
• pop-os/icon-theme (tree listing 2026-10-03): Pop/scalable/apps/utilities-terminal-symbolic.svg — https://github.com/pop-os/icon-theme
• DropTerm itself: Cargo.toml L1-12; src/main.rs L45-69; res/io.github.l1br3_io.CosmicExtDropterm.desktop; ROADMAP.md L31, L35