fix(ui): don't let a bare shell name outrank the cwd/repo title

pane_title_of() picked any non-empty PaneRecord.title, but an idle
terminal's foreground process is just the shell itself (zsh, bash, ...).
That made almost every idle-shell workspace show up as "zsh" in the
sidebar instead of the far more useful cwd/repo-derived name, which
defeats the "cwd as final fallback" intent of this change.

Skip bare shell process names when picking a pane title, so the
process-name fallback only kicks in for genuinely distinctive
foreground processes (nvim, an agent, ...).

crates/tty7-core/src/core/shells.rs

@@ -27,6 +27,37 @@ pub struct ShellInventory {
     pub default_name: String,
 }
 
+/// Common interactive-shell process names, lowercase and without a
+/// platform-specific extension. Anything that lands in here is what a pane
+/// looks like at an idle prompt — not distinctive enough to stand in for a
+/// pane's cwd/repo name when picking a display title.
+const BARE_SHELL_NAMES: &[&str] = &[
+    "sh",
+    "bash",
+    "zsh",
+    "fish",
+    "dash",
+    "ksh",
+    "tcsh",
+    "csh",
+    "nu",
+    "elvish",
+    "xonsh",
+    "pwsh",
+    "powershell",
+    "cmd",
+    "wsl",
+];
+
+/// True when `name` is a bare interactive-shell process name (e.g. the
+/// foreground process of an idle terminal), so callers that want a
+/// *distinctive* title should skip it and fall back to something else.
+pub fn is_bare_shell_name(name: &str) -> bool {
+    let lower = name.trim().to_ascii_lowercase();
+    let lower = lower.strip_suffix(".exe").unwrap_or(&lower);
+    BARE_SHELL_NAMES.contains(&lower)
+}
+
 pub fn inventory() -> ShellInventory {
     let configured = crate::core::config::shell_command();
     ShellInventory {
@@ -409,4 +440,16 @@ mod tests {
         assert!(!default_shell_name(None).is_empty());
         assert!(!default_shell_name(Some("  ")).is_empty());
     }
+
+    #[test]
+    fn bare_shell_names_are_recognized_case_and_extension_insensitively() {
+        assert!(is_bare_shell_name("zsh"));
+        assert!(is_bare_shell_name("bash"));
+        assert!(is_bare_shell_name("PowerShell"));
+        assert!(is_bare_shell_name("pwsh.exe"));
+        assert!(is_bare_shell_name("CMD.EXE"));
+        assert!(!is_bare_shell_name("nvim"));
+        assert!(!is_bare_shell_name("claude"));
+        assert!(!is_bare_shell_name(""));
+    }
 }

src/ui/machine_mirror.rs

@@ -276,7 +276,7 @@ fn pane_title_of<'a>(ws: &Workspace, panes: &'a [PaneRecord]) -> Option<&'a str>
         .flat_map(|t| t.root.pane_ids())
         .filter_map(|id| panes.iter().find(|p| p.id == id))
         .map(|p| p.title.trim())
-        .find(|title| !title.is_empty())
+        .find(|title| !title.is_empty() && !tty7_core::core::shells::is_bare_shell_name(title))
 }
 
 pub fn subject_path_of(ws: &Workspace, panes: &[PaneRecord]) -> Option<String> {
@@ -530,6 +530,13 @@ mod tests {
             "a live process name is more distinctive than the cwd group"
         );
 
+        panes[0].title = "zsh".into();
+        assert_eq!(
+            display_name_of(&ws, &panes),
+            "tty7",
+            "an idle shell prompt is not distinctive — cwd/repo name should win"
+        );
+
         ws.name = Some("  Release prep  ".into());
         assert_eq!(display_name_of(&ws, &panes), "Release prep");