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workspace-manager: don't restore Firefox windows when sway tree query fails
Under load, the swaymsg get_tree subprocess could time out, the host
returned an empty windows list, and the extension treated that as "no
Firefox windows anywhere" — restoring a window for a workspace that
already had one. Distinguish query failure from a genuinely empty
result and skip restoration when state is unknown.
author
lassulus
date
(May 8, 2026, 11:09 PM CEST)
commit
a37596b8
a37596b84288288d3ca264eb88c5f077d8a016b2
parent
bfd45dcf
bfd45dcf0015d450927a2e5a76e287b4d1cd4826
+71
-44
+18
-7
tools/workspace-manager/workspace-tabs-host.py
+18
-7
tools/workspace-manager/workspace-tabs-host.py
···
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sys.stdout.buffer.flush()
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-
def run(cmd: list[str]) -> str:
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def run(cmd: list[str], timeout: float = 2) -> str:
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"""Run a command and return stripped stdout, or empty string on failure."""
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try:
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r = subprocess.run(cmd, capture_output=True, text=True, timeout=2) # noqa: S603
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r = subprocess.run(cmd, capture_output=True, text=True, timeout=timeout) # noqa: S603
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except (OSError, subprocess.TimeoutExpired):
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return ""
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return r.stdout.strip() if r.returncode == 0 else ""
···
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return {}
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-
def get_firefox_windows() -> list[dict[str, str]]:
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"""Get all Firefox windows and their workspaces from sway tree."""
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def get_firefox_windows() -> list[dict[str, str]] | None:
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"""Get all Firefox windows and their workspaces from sway tree.
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Returns None if the sway tree could not be queried (so callers can
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distinguish "no Firefox windows" from "we don't know"). Otherwise
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returns the list of Firefox windows, possibly empty.
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"""
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raw = run(["swaymsg", "-t", "get_tree", "-r"], timeout=5)
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if not raw:
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return None
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try:
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tree: dict[str, Any] = json.loads(run(["swaymsg", "-t", "get_tree", "-r"]))
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tree: dict[str, Any] = json.loads(raw)
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except (json.JSONDecodeError, ValueError):
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return []
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return None
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results: list[dict[str, str]] = []
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···
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run(["swaymsg", "move", "container", "to", "workspace", msg.get("name", "")])
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return {"id": mid, "ok": True}
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if cmd == "map_windows":
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return {"id": mid, "windows": get_firefox_windows()}
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windows = get_firefox_windows()
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if windows is None:
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return {"id": mid, "error": "Failed to query sway tree"}
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return {"id": mid, "windows": windows}
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if cmd == "save_tabs":
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workspace = msg.get("workspace", "")
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tabs = msg.get("tabs", [])
+53
-37
tools/workspace-manager/firefox-extension/background.js
+53
-37
tools/workspace-manager/firefox-extension/background.js
···
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// ── Firefox window <-> workspace mapping ────────────────────
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// Throws on query failure so callers can distinguish "no Firefox windows"
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// from "we don't know" — a silent empty result here under load caused
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// duplicate window restoration.
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async function getFirefoxWindowMappings() {
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try {
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const resp = await sendNative("map_windows");
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if (!resp.windows) return new Map();
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const resp = await sendNative("map_windows");
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if (resp.error) throw new Error(resp.error);
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if (!resp.windows) throw new Error("map_windows: no windows field");
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const allWindows = await browser.windows.getAll({ populate: true });
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const result = new Map();
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const matched = new Set();
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const allWindows = await browser.windows.getAll({ populate: true });
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const result = new Map();
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const matched = new Set();
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for (const mapping of resp.windows) {
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const swayTitle = mapping.windowTitle || "";
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for (const win of allWindows) {
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if (matched.has(win.id) || win.id === anchorWindowId) continue;
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const activeTab = win.tabs && win.tabs.find((t) => t.active);
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if (
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activeTab &&
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activeTab.title &&
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swayTitle.startsWith(activeTab.title)
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) {
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result.set(mapping.workspace, win.id);
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matched.add(win.id);
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break;
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}
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for (const mapping of resp.windows) {
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const swayTitle = mapping.windowTitle || "";
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for (const win of allWindows) {
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if (matched.has(win.id) || win.id === anchorWindowId) continue;
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const activeTab = win.tabs && win.tabs.find((t) => t.active);
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if (
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activeTab &&
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activeTab.title &&
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swayTitle.startsWith(activeTab.title)
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) {
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result.set(mapping.workspace, win.id);
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matched.add(win.id);
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break;
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}
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}
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return result;
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} catch (e) {
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return new Map();
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}
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return result;
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}
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async function getWorkspacesWithFirefox() {
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try {
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const resp = await sendNative("map_windows");
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if (!resp.windows) return new Set();
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return new Set(resp.windows.map((w) => w.workspace));
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-
} catch (e) {
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return new Set();
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}
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const resp = await sendNative("map_windows");
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if (resp.error) throw new Error(resp.error);
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if (!resp.windows) throw new Error("map_windows: no windows field");
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return new Set(resp.windows.map((w) => w.workspace));
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}
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// ── Anchor window (keeps Firefox alive) ─────────────────────
···
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// ── Tab saving (to workspace file) ─────────────────────────
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async function saveTabsForWorkspace(workspace) {
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async function saveTabsForWorkspace(workspace, mappings) {
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if (!workspace) return;
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const mappings = await getFirefoxWindowMappings();
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const windowId = mappings.get(workspace);
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if (!windowId) return;
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···
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}
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async function saveAllTabs() {
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const mappings = await getFirefoxWindowMappings();
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let mappings;
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try {
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mappings = await getFirefoxWindowMappings();
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} catch (e) {
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console.warn("Skipping save — could not query window mappings:", e);
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return;
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}
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for (const [workspace] of mappings) {
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await saveTabsForWorkspace(workspace);
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await saveTabsForWorkspace(workspace, mappings);
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}
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}
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···
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// Don't restore tabs during startup — only after user switches workspace
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if (!initialized) return;
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// Check if this workspace already has a Firefox window
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const withFirefox = await getWorkspacesWithFirefox();
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// Check if this workspace already has a Firefox window. If we can't tell
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// (e.g. swaymsg timed out under load), skip — restoring blindly would
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// duplicate an existing window.
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let withFirefox;
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try {
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withFirefox = await getWorkspacesWithFirefox();
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} catch (e) {
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console.warn(`Skipping restore for ${workspace} — query failed:`, e);
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return;
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}
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if (withFirefox.has(workspace)) return;
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// No Firefox window — restore saved tabs
···
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// Restore tabs for the initial workspace if it has saved tabs from a previous session
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if (lastWorkspace) {
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const withFirefox = await getWorkspacesWithFirefox();
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let withFirefox;
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try {
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withFirefox = await getWorkspacesWithFirefox();
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} catch (e) {
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console.warn("Skipping initial restore — query failed:", e);
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return;
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}
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if (!withFirefox.has(lastWorkspace)) {
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const resp = await sendNative("get_tabs", { workspace: lastWorkspace });
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const tabs = resp.tabs || [];