test(errors): add #3020 test extensions — Plan-mode denial passes through verbatim, bare/model denials get the suffix; Model-Not-Exist + OpenAI-style rejections annotated; conflict error includes elapsed time; tighten mode-word predicate so 'model' no longer matches

Co-Authored-By: Claude <noreply@anthropic.com>
https://claude.ai/code/session_018zaP8vUfTAsrE38L6h6fw5

crates/tui/src/core/engine/dispatch.rs

@@ -99,6 +99,15 @@ pub(super) fn caller_allowed_for_tool(
     requested == "direct"
 }
 
+/// Whole-word check for "mode"/"modes" — a plain `contains("mode")` also
+/// matched "model", letting provider model errors skip the actionable-hint
+/// suffix (#3020).
+fn mentions_mode_word(lower: &str) -> bool {
+    lower
+        .split(|ch: char| !ch.is_ascii_alphanumeric())
+        .any(|word| word == "mode" || word == "modes")
+}
+
 pub(super) fn format_tool_error(err: &ToolError, tool_name: &str) -> String {
     match err {
         ToolError::InvalidInput { message } => {
@@ -123,7 +132,7 @@ pub(super) fn format_tool_error(err: &ToolError, tool_name: &str) -> String {
             // "switch to Agent, Goal, or YOLO mode" which confuses the model.
             if lower.contains("current tool catalog")
                 || lower.contains("did you mean:")
-                || lower.contains("mode")
+                || mentions_mode_word(&lower)
                 || lower.contains("allow_shell")
                 || lower.contains("feature flag")
             {
@@ -137,7 +146,7 @@ pub(super) fn format_tool_error(err: &ToolError, tool_name: &str) -> String {
         ToolError::PermissionDenied { message } => {
             let lower = message.to_ascii_lowercase();
             // #3020: Pass through messages that already name the denial cause.
-            if lower.contains("mode")
+            if mentions_mode_word(&lower)
                 || lower.contains("allow_shell")
                 || lower.contains("denied by user")
             {

crates/tui/src/core/engine/tests.rs

@@ -486,6 +486,33 @@ fn tool_error_messages_include_actionable_hints() {
     let timeout = ToolError::Timeout { seconds: 5 };
     let formatted = format_tool_error(&timeout, "exec_shell");
     assert!(formatted.contains("timed out"));
+
+    // #3020: Plan-mode denials already explain the fix — pass through
+    // verbatim, with no conflicting "Adjust approval mode" suffix.
+    let plan_denied = ToolError::permission_denied(
+        "'exec_shell' is not available in Plan mode — switch to Agent, Goal, or YOLO mode to run commands and code.",
+    );
+    let formatted = format_tool_error(&plan_denied, "exec_shell");
+    assert_eq!(
+        formatted,
+        "'exec_shell' is not available in Plan mode — switch to Agent, Goal, or YOLO mode to run commands and code."
+    );
+
+    // Bare denials still get the actionable suffix.
+    let bare_denied = ToolError::permission_denied("nope");
+    let formatted = format_tool_error(&bare_denied, "exec_shell");
+    assert!(
+        formatted.contains("Adjust approval mode or request permission"),
+        "{formatted}"
+    );
+
+    // "model" must not satisfy the "mode" pass-through check.
+    let model_denied = ToolError::permission_denied("requested model is not allowed");
+    let formatted = format_tool_error(&model_denied, "agent_open");
+    assert!(
+        formatted.contains("Adjust approval mode or request permission"),
+        "{formatted}"
+    );
 }
 
 #[test]

crates/tui/src/tools/subagent/tests.rs

@@ -1489,6 +1489,12 @@ async fn spawn_duplicate_session_name_error_names_conflicting_agent() {
         msg.contains("running"),
         "includes the conflicting status: {msg}"
     );
+    // #3020: elapsed time lets the parent distinguish a live worker from a
+    // stale earlier spawn.
+    assert!(
+        msg.contains("started ") && msg.contains(" ago"),
+        "includes elapsed time since spawn: {msg}"
+    );
 }
 
 #[tokio::test]
@@ -2074,6 +2080,23 @@ fn annotate_child_model_error_adds_actionable_hint() {
 
     let unrelated = annotate_child_model_error("connection reset by peer", "kimi-k2");
     assert_eq!(unrelated, "connection reset by peer");
+
+    // #3020: provider rejections that classify as Internal (not
+    // Authorization/State) still get the hint via raw-text matching.
+    let not_exist = annotate_child_model_error("Model Not Exist", "kimi-k2");
+    assert!(
+        not_exist.contains("retry agent_open"),
+        "DeepSeek-style rejection gets the hint: {not_exist}"
+    );
+
+    let openai_style = annotate_child_model_error(
+        "The model `gpt-5.5-nano` does not exist or you do not have access to it.",
+        "gpt-5.5-nano",
+    );
+    assert!(
+        openai_style.contains("retry agent_open"),
+        "OpenAI-style rejection gets the hint: {openai_style}"
+    );
 }
 
 #[test]