feat(claudbg-37cj): add --[no-]color global flag and NO_COLOR support

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.beans/claudbg-37cj--add-no-color-global-flag-and-no-color-env-var-supp.md

@@ -0,0 +1,11 @@
+---
+# claudbg-37cj
+title: Add --[no-]color global flag and NO_COLOR env var support
+status: todo
+type: task
+created_at: 2026-03-31T00:32:57Z
+updated_at: 2026-03-31T00:32:57Z
+parent: claudbg-qpfe
+---
+
+Add `--color` / `--no-color` as a global CLI flag (available on all commands). When not specified, auto-detect: enable color if stdout is a tty and NO_COLOR is unset/empty. Honor the NO_COLOR environment variable (any non-empty value → disable color), per the NO_COLOR spec. This flag controls all ANSI output in the CLI (transcripts etc).

src/cli.rs

@@ -116,6 +116,37 @@ pub struct GlobalOpts {
     /// Valid values: thinking, output. Example: --include thinking,output
     #[arg(long, global = true, default_value = "")]
     pub include: IncludeList,
+    /// Force color output even when not writing to a terminal.
+    #[arg(long, global = true, overrides_with = "no_color")]
+    pub color: bool,
+    /// Disable color output (also honored via the NO_COLOR env var).
+    #[arg(long = "no-color", global = true, overrides_with = "color")]
+    pub no_color: bool,
+}
+
+impl GlobalOpts {
+    /// Determine whether color output should be enabled.
+    ///
+    /// Priority (highest → lowest):
+    /// 1. `NO_COLOR` env var set to a non-empty value → disabled.
+    /// 2. `--no-color` flag passed → disabled.
+    /// 3. `--color` flag passed → enabled.
+    /// 4. Auto-detect: enabled iff stdout is a TTY.
+    pub fn color_enabled(&self) -> bool {
+        use std::io::IsTerminal as _;
+
+        // NO_COLOR spec: any non-empty value disables color.
+        if std::env::var("NO_COLOR").is_ok_and(|v| !v.is_empty()) {
+            return false;
+        }
+        if self.no_color {
+            return false;
+        }
+        if self.color {
+            return true;
+        }
+        std::io::stdout().is_terminal()
+    }
 }
 
 /// Top-level subcommands.

src/commands/agents.rs

@@ -464,6 +464,8 @@ mod tests {
             output: OutputFormat::Table,
             verbose: false,
             include: IncludeList::default(),
+            color: false,
+            no_color: false,
         }
     }
 

src/commands/sessions.rs

@@ -647,6 +647,8 @@ mod tests {
             output: OutputFormat::Table,
             verbose: false,
             include: IncludeList::default(),
+            color: false,
+            no_color: false,
         }
     }