fix: the picker panicked when TERM named no usable terminal

CHANGELOG.md

@@ -7,6 +7,18 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- **The picker no longer panics when `TERM` names no usable terminal.** With `TERM` unset,
+  or naming a terminfo entry the machine does not have, `dl`'s workspace picker (and
+  `aid resume`'s) aborted with a panic before it drew a row. A name like `xterm-kitty`
+  with no entry behind it did not panic but drew a garbled picker, because the entry it
+  got could not move the cursor. Now any `TERM` whose entry cannot move the cursor is
+  drawn as `xterm-256color`, the picker says so once it closes, and the session it opens
+  gets your own `TERM` back. When `xterm-256color` cannot move the cursor here either,
+  the picker is not started, and the command says why and how to name the workspace
+  instead.
+
 ## [0.57.0] - 2026-09-28
 
 ### Added

rust/Cargo.toml

@@ -36,6 +36,11 @@ toml = "0.9"
 toml_edit = "0.23"
 clap = { version = "4", features = ["derive"] }
 skim = "0.20"
+# The terminfo lookup skim's terminal setup makes and unwraps, made first so a
+# `TERM` it would panic on, or draw nothing with, can be replaced (dl's
+# `select.rs`). The version skim resolves, so the answer is the one skim would
+# have reached.
+term = "0.7"
 # flock(2) — per open file description, kernel-released — as Python's
 # fcntl.flock. fd-lock 4 gets its semantics from the same rustix call, but its
 # guard borrows the RwLock and unlocks on drop, so an owned guard would have to

rust/aid/tests/interactive.rs

@@ -474,6 +474,58 @@ fn a_resume_with_no_workspace_resumes_the_row_the_picker_took() {
     );
 }
 
+#[test]
+fn a_resume_with_no_workspace_on_a_terminal_no_entry_can_draw_on_says_how_to_name_one() {
+    // `TERMINFO_DIRS` is the whole of the terminfo search when it is set, so an
+    // empty one leaves no entry, the fallback's included, that can move the
+    // cursor. No picker can be drawn, and aid says how to name the workspace
+    // instead of opening anything.
+    let world = World::with(&["--warm"]);
+    let nothing = world.root.join("terminfo");
+    std::fs::create_dir_all(&nothing).expect("an empty terminfo directory");
+    let mut session = PtyAid::spawn(
+        &world,
+        &["resume"],
+        &[
+            ("TERM", "xterm-no-such-entry"),
+            ("TERMINFO_DIRS", &nothing.display().to_string()),
+        ],
+    );
+    let seen = Arc::clone(&session.seen);
+    // Bounded: a picker that opened anyway would wait on this pty for ever.
+    let mut code = None;
+    wait_for(|| {
+        code = session.child.try_wait().expect("aid's status");
+        code.is_some()
+    });
+    let _ = session.child.kill();
+    assert_eq!(code.map(|status| status.exit_code()), Some(1));
+
+    // The reader thread may still hold the last bytes, so the line is waited for.
+    let said = || String::from_utf8_lossy(&seen.lock().expect("the pty buffer")).into_owned();
+    assert!(
+        wait_for(|| said().contains(
+            "so aid resume cannot draw its picker. Name the workspace instead: \
+             aid resume <workspace>"
+        )),
+        "the refusal was not given; the pty said:\n{:?}",
+        said()
+    );
+    assert!(
+        !said().contains("\x1b[?1049h"),
+        "a picker was opened anyway: {:?}",
+        said()
+    );
+    assert!(
+        !world
+            .devpod_calls()
+            .iter()
+            .any(|call| call.starts_with("devpod ssh")),
+        "a refused picker opened a session: {:?}",
+        world.devpod_calls()
+    );
+}
+
 #[test]
 fn the_boot_runs_while_the_prompt_is_still_being_typed() {
     // The overlap itself: a stopped workspace's `devpod up` is on the shim's log

rust/dl/Cargo.toml

@@ -18,6 +18,7 @@ libc = { workspace = true }
 serde = { workspace = true }
 serde_json = { workspace = true }
 skim = { workspace = true }
+term = { workspace = true }
 
 # The released package ships two binaries, and a maturin bin-wheel ships the bin
 # targets of exactly *one* cargo package (maturin 1.14 asks cargo metadata for

rust/dl/src/commands.rs

@@ -1679,6 +1679,17 @@
             println!("{}", select::invitation(arity));
             no_pick()
         }
+        select::Pick::Undrawable(reason) => {
+            let line = match &verb {
+                Verb::Attach { .. } => "dl <workspace>".to_owned(),
+                Verb::Run(..) => "dl <workspace> -- <command>".to_owned(),
+                verb => format!("dl <workspace> {}", verb.word()),
+            };
+            eprintln!(
+                "{reason}, so the picker cannot be drawn. Name the workspace instead: {line}"
+            );
+            no_pick()
+        }
     }
 }
 
@@ -1691,7 +1702,8 @@
 /// grammar. An empty list keeps dl's sentence, which says how to make a workspace.
 /// A run with no terminal gets one of its own in place of the invitation, which
 /// would ask for a pick nobody can make: it says a terminal is missing and how to
-/// name the workspace instead.
+/// name the workspace instead. So does a terminal that no terminfo entry here can
+/// draw on.
 pub(crate) fn pick_one(runner: &dyn Runner) -> Result<String, Ending> {
     // The picker reads each row's clone under the cache for its columns. With no
     // cache there is nothing to draw, and the refusal is every other command's.
@@ -1719,6 +1731,13 @@
             );
             Err(Ending::Refused)
         }
+        select::Pick::Undrawable(reason) => {
+            eprintln!(
+                "{reason}, so aid resume cannot draw its picker. Name the workspace instead: \
+                 aid resume <workspace>"
+            );
+            Err(Ending::Refused)
+        }
     }
 }