fix: preserve session layouts across shutdown and restore failures (#4400)

* fix: preserve session layouts across shutdown and restore failures

refs #4320

* test: update subscription fixture for pane restore errors

---------

Co-authored-by: JJ Liebig <jonathan.liebig@gmail.com>

3 files changed, 62 insertions, 3 deletions

diff --git a/src/app/agent_resume.rs b/src/app/agent_resume.rs
index 2cbd93ab..9bf2157f 100644
--- a/src/app/agent_resume.rs
+++ b/src/app/agent_resume.rs
@@ -233,6 +233,15 @@ impl App {
             return false;
         };
 
+        if !cwd.is_dir() {
+            if let Some(terminal) = self.state.terminals.get_mut(&terminal_id) {
+                terminal.pending_agent_resume_plan = None;
+                terminal.restore_error = Some("Saved directory is unavailable. Restore the directory and restart this session.".into());
+                terminal.revision = terminal.revision.saturating_add(1);
+            }
+            return true;
+        }
+
         let runtime = match crate::terminal::TerminalRuntime::spawn(
             pane_id,
             rows,
@@ -257,9 +266,11 @@ impl App {
                     "failed to start shell for deferred agent resume"
                 );
                 if let Some(terminal) = self.state.terminals.get_mut(&terminal_id) {
-                    terminal.clear_agent_runtime_identity_after_respawn();
+                    terminal.pending_agent_resume_plan = None;
+                    terminal.restore_error = Some(format!("Could not start the saved shell: {err}. Fix the shell configuration and restart this session."));
+                    terminal.revision = terminal.revision.saturating_add(1);
                 }
-                return false;
+                return true;
             }
         };
 
@@ -380,6 +391,49 @@ mod tests {
 
     #[cfg(unix)]
     #[tokio::test]
+    async fn failed_deferred_restore_keeps_session_reference_without_retrying_elsewhere() {
+        for missing_shell in [false, true] {
+            let mut app = test_app();
+            let workspace = crate::workspace::Workspace::test_new("unavailable");
+            let pane_id = workspace.tabs[0].root_pane;
+            let terminal_id = workspace.terminal_id(pane_id).unwrap().clone();
+            app.state.workspaces = vec![workspace];
+            app.state.active = Some(0);
+            app.state.ensure_test_terminals();
+            if missing_shell {
+                app.state.default_shell = "__herdr_missing_resume_shell__".into();
+            }
+            let terminal = app.state.terminals.get_mut(&terminal_id).unwrap();
+            if !missing_shell {
+                terminal.cwd = std::env::current_dir()
+                    .unwrap()
+                    .join("__herdr_missing_resume_cwd__");
+                assert!(!terminal.cwd.exists());
+            }
+            let session = crate::agent_resume::PersistedAgentSession {
+                source: "herdr:codex".into(),
+                agent: "codex".into(),
+                session_ref: crate::agent_resume::AgentSessionRef::id("resume-test").unwrap(),
+            };
+            terminal.persisted_agent_session = Some(session.clone());
+            terminal.pending_agent_resume_plan = Some(crate::agent_resume::AgentResumePlan {
+                agent: "codex".into(),
+                argv: long_running_test_argv(),
+                dedupe_key: "resume-test".into(),
+            });
+            app.start_pending_agent_resume_for_terminal(&terminal_id, 24, 80, true);
+            assert!(app.terminal_runtimes.get(&terminal_id).is_none());
+            let terminal = &app.state.terminals[&terminal_id];
+            assert!(terminal.pending_agent_resume_plan.is_none());
+            assert_eq!(terminal.persisted_agent_session.as_ref(), Some(&session));
+            assert!(terminal.restore_error.is_some());
+            assert!(!app.has_pending_agent_resumes());
+            assert!(!app.start_pending_agent_resume_for_terminal(&terminal_id, 24, 80, true));
+        }
+    }
+
+    #[cfg(unix)]
+    #[tokio::test]
     async fn pending_agent_resume_waits_for_host_theme_before_launch() {
         let mut app = test_app();
         let workspace = crate::workspace::Workspace::test_new("restored");
diff --git a/src/app/creation.rs b/src/app/creation.rs
index af34e540..05736fe5 100644
--- a/src/app/creation.rs
+++ b/src/app/creation.rs
@@ -340,6 +340,7 @@ impl App {
             foreground_cwd: ws.tabs[tab_idx]
                 .foreground_cwd_for_pane(pane_id, &self.terminal_runtimes)
                 .map(|cwd| cwd.display().to_string()),
+            restore_error: terminal.restore_error.clone(),
             label: terminal.manual_label.clone(),
             agent: terminal.effective_agent_label().map(str::to_string),
             title: presentation.title,
diff --git a/src/app/session.rs b/src/app/session.rs
index 08c4cd44..509d4050 100644
--- a/src/app/session.rs
+++ b/src/app/session.rs
@@ -49,7 +49,11 @@ impl App {
                 self.state.selected,
             );
             let history = self.persist_pane_history.then(|| {
-                crate::persist::capture_history(&self.state.workspaces, &self.terminal_runtimes)
+                crate::persist::capture_history(
+                    &snapshot,
+                    &self.state.workspaces,
+                    &self.terminal_runtimes,
+                )
             });
             SessionSaveJob::Save { snapshot, history }
         }