From 0f521ce289c36565ee1681d38168b62bd4eeaf5f Mon Sep 17 00:00:00 2001
From: kronberger-droid <kronberger@proton.me>
Date: Thu, 17 Sep 2026 18:57:07 +0200
Subject: [PATCH] refactor(engine): take the TERM=dumb answer from the painter

The engine read `TERM` on every paint while the painter answers from a
flag cached at construction and on resize, so after a mid-session change
the colors and the skipped escapes could disagree. ANSI coloring now
follows that cache too, thus it no longer tracks `TERM` between resizes.

Follow-up to #1183.
---
 src/engine.rs            | 10 ++++------
 src/painting/painter.rs  |  6 ++++++
 src/prompt/default.rs    |  5 +++--
 src/utils/environment.rs | 19 ++++++-------------
 4 files changed, 19 insertions(+), 21 deletions(-)

diff --git a/src/engine.rs b/src/engine.rs
index 8b82a4ae1..69d504843 100644
--- a/src/engine.rs
+++ b/src/engine.rs
@@ -35,10 +35,7 @@ use {
             kitty::KittyProtocolGuard,
             semantic_prompt::{Osc133ClickEventsMarkers, SemanticPromptMarkers},
         },
-        utils::{
-            environment::{term_supports_ansi, var_os},
-            text_manipulation,
-        },
+        utils::text_manipulation,
         AbbrExpandContext, AutoPairAction, AutoPairContext, AutoPairs, Direction, EditCommand,
         ExampleHighlighter, Highlighter, LineBuffer, Menu, MenuEvent, MouseButton, Prompt,
         PromptHistorySearch, ReedlineMenu, Signal, UndoBehavior, ValidationResult, Validator,
@@ -555,9 +552,10 @@ impl Reedline {
     ///
     /// ANSI coloring requires both the Reedline configuration to enable it and
     /// terminal support; `TERM=dumb` takes precedence over `with_ansi_colors(true)`.
+    /// The painter holds the terminal policy, so the colors and the escapes it
+    /// skips cannot disagree.
     fn effective_ansi_coloring(&self) -> bool {
-        let term = var_os("TERM");
-        self.use_ansi_coloring && term_supports_ansi(term.as_deref())
+        self.use_ansi_coloring && !self.painter.term_is_dumb()
     }
 
     /// A builder which enables or disables the use of ansi coloring in the prompt
diff --git a/src/painting/painter.rs b/src/painting/painter.rs
index 8b60dffdd..601913f24 100644
--- a/src/painting/painter.rs
+++ b/src/painting/painter.rs
@@ -481,6 +481,12 @@ impl Painter {
         }
     }
 
+    /// Whether the terminal declared itself `TERM=dumb`, as of construction
+    /// or the last resize.
+    pub(crate) fn term_is_dumb(&self) -> bool {
+        self.term_is_dumb
+    }
+
     /// Computes the right prompt position when the terminal can position it.
     fn compute_right_prompt(
         &self,
diff --git a/src/prompt/default.rs b/src/prompt/default.rs
index 7be07e890..bab4f87d0 100644
--- a/src/prompt/default.rs
+++ b/src/prompt/default.rs
@@ -10,6 +10,7 @@
 //! visual, helix's select) would otherwise have nowhere to sit.
 
 use crate::prompt::base::PromptHelixMode;
+use crate::utils::environment::var_os;
 use crate::{Prompt, PromptEditMode, PromptHistorySearch, PromptHistorySearchStatus, PromptViMode};
 
 use {
@@ -148,8 +149,8 @@ fn get_working_dir() -> Result<String, std::io::Error> {
     let cwd = env::current_dir()?;
     // `USERPROFILE` on Windows, `HOME` elsewhere. Avoids `env::home_dir()`,
     // which is buggy on Windows before 1.85 (above our 1.63 MSRV).
-    let home = crate::utils::environment::var_os("USERPROFILE")
-        .or_else(|| crate::utils::environment::var_os("HOME"))
+    let home = var_os("USERPROFILE")
+        .or_else(|| var_os("HOME"))
         .map(std::path::PathBuf::from);
     Ok(format_working_dir(&cwd, home.as_deref()))
 }
diff --git a/src/utils/environment.rs b/src/utils/environment.rs
index ee4ebb1f2..eaeaac7a7 100644
--- a/src/utils/environment.rs
+++ b/src/utils/environment.rs
@@ -14,29 +14,22 @@ pub(crate) fn term_is_dumb(term: Option<&OsStr>) -> bool {
     term == Some(OsStr::new("dumb"))
 }
 
-/// Whether ANSI coloring is appropriate for the declared terminal.
-///
-/// An unset or non-dumb `TERM` preserves the configured Reedline behavior.
-pub(crate) fn term_supports_ansi(term: Option<&OsStr>) -> bool {
-    !term_is_dumb(term)
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
 
     #[test]
-    fn term_dumb_does_not_support_ansi() {
-        assert!(!term_supports_ansi(Some(OsStr::new("dumb"))));
+    fn term_dumb_is_dumb() {
+        assert!(term_is_dumb(Some(OsStr::new("dumb"))));
     }
 
     #[test]
-    fn regular_term_supports_ansi() {
-        assert!(term_supports_ansi(Some(OsStr::new("xterm-256color"))));
+    fn regular_term_is_not_dumb() {
+        assert!(!term_is_dumb(Some(OsStr::new("xterm-256color"))));
     }
 
     #[test]
-    fn unset_term_does_not_disable_ansi() {
-        assert!(term_supports_ansi(None));
+    fn unset_term_is_not_dumb() {
+        assert!(!term_is_dumb(None));
     }
 }