feat: add session-color patch for env-based prompt bar color

Set the session prompt bar color via TWEAKCC_SESSION_COLOR env var.
Intended for use in wrapper scripts (e.g. ccw) that determine color
based on the working directory before launching Claude Code.

Valid values: red, blue, green, yellow, purple, orange, pink, cyan.
Invalid or unset values are silently ignored (no color applied).

How it works:
Claude Code has two app state initialization sites — the CLI
bootstrap (which builds initialState inline with dynamic values like
effortValue, fastMode) and the default state factory u3H() used as
fallback. Neither includes standaloneAgentContext, so it defaults to
undefined and the prompt bar shows no color.

The patch injects a standaloneAgentContext IIFE into both sites that
reads TWEAKCC_SESSION_COLOR at startup, validates it against the
hardcoded allowed list, and returns {name:"",color:value} or void 0.
This is the same state shape that /color sets interactively.

On session resume, Claude Code restores the color from the session
file, so the env var only affects new sessions.

Author: VitalyOstanin

src/patches/index.ts

@@ -73,6 +73,7 @@ import { writeWorktreeMode } from './worktreeMode';
 import { writeAllowCustomAgentModels } from './allowCustomAgentModels';
 import { writeVoiceMode } from './voiceMode';
 import { writeChannelsMode } from './channelsMode';
+import { writeSessionColor } from './sessionColor';
 import {
   restoreNativeBinaryFromBackup,
   restoreClijsFromBackup,
@@ -174,6 +175,13 @@ const PATCH_DEFINITIONS = [
     group: PatchGroup.ALWAYS_APPLIED,
     description: `Statusline updates will be properly throttled instead of queued (or debounced)`,
   },
+  {
+    id: 'session-color',
+    name: 'Session color from env',
+    group: PatchGroup.ALWAYS_APPLIED,
+    description:
+      'Set session prompt bar color via TWEAKCC_SESSION_COLOR env var',
+  },
   // Misc Configurable
   {
     id: 'model-customizations',
@@ -888,6 +896,9 @@ export const applyCustomization = async (
       fn: c => writeChannelsMode(c),
       condition: !!config.settings.misc?.enableChannelsMode,
     },
+    'session-color': {
+      fn: c => writeSessionColor(c),
+    },
   };
 
   // ==========================================================================

src/patches/sessionColor.test.ts

@@ -0,0 +1,55 @@
+import { describe, it, expect } from 'vitest';
+import { writeSessionColor } from './sessionColor';
+
+const makeCLIState = () =>
+  'effortValue:oR(w.effort),' +
+  'activeOverlays:new Set,fastMode:cP8(N5),' +
+  '...(uF()&&d1&&{advisorModel:d1})';
+
+const makeDefaultState = () =>
+  'effortValue:void 0,' + 'activeOverlays:new Set,fastMode:!1}';
+
+const makeBoth = () =>
+  'first{' + makeDefaultState() + 'second{' + makeCLIState();
+
+describe('sessionColor', () => {
+  describe('writeSessionColor', () => {
+    it('should inject into CLI initialState', () => {
+      const result = writeSessionColor(makeCLIState());
+      expect(result).not.toBeNull();
+      expect(result).toContain('TWEAKCC_SESSION_COLOR');
+      expect(result).toContain('{name:"",color:__c}');
+    });
+
+    it('should inject into default app state', () => {
+      const result = writeSessionColor(makeDefaultState());
+      expect(result).not.toBeNull();
+      expect(result).toContain('TWEAKCC_SESSION_COLOR');
+    });
+
+    it('should patch both locations when both present', () => {
+      const result = writeSessionColor(makeBoth())!;
+      expect(result).not.toBeNull();
+      const count = (result.match(/TWEAKCC_SESSION_COLOR/g) || []).length;
+      expect(count).toBe(2);
+    });
+
+    it('should validate color against allowed list', () => {
+      const result = writeSessionColor(makeCLIState())!;
+      expect(result).toContain('.includes(__c)');
+      expect(result).toContain('"green"');
+      expect(result).toContain('"cyan"');
+    });
+
+    it('should be idempotent', () => {
+      const first = writeSessionColor(makeBoth())!;
+      const second = writeSessionColor(first)!;
+      expect(second).toBe(first);
+    });
+
+    it('should return null when no pattern found', () => {
+      const result = writeSessionColor('not a valid file');
+      expect(result).toBeNull();
+    });
+  });
+});

src/patches/sessionColor.ts

@@ -0,0 +1,63 @@
+import { showDiff } from './index';
+import { debug } from '../utils';
+
+const VALID_COLORS = [
+  'red',
+  'blue',
+  'green',
+  'yellow',
+  'purple',
+  'orange',
+  'pink',
+  'cyan',
+];
+
+const INJECTION =
+  `,standaloneAgentContext:` +
+  `(()=>{` +
+  `let __c=process.env.TWEAKCC_SESSION_COLOR;` +
+  `return __c&&${JSON.stringify(VALID_COLORS)}.includes(__c)` +
+  `?{name:"",color:__c}` +
+  `:void 0` +
+  `})()`;
+
+export const writeSessionColor = (oldFile: string): string | null => {
+  if (oldFile.includes('TWEAKCC_SESSION_COLOR')) {
+    return oldFile;
+  }
+
+  const patterns = [
+    /,activeOverlays:new Set,fastMode:[$\w]+\([$\w]+\)/,
+    /,activeOverlays:new Set,fastMode:!1\}/,
+  ];
+
+  let result = oldFile;
+  let patched = false;
+
+  for (const pattern of patterns) {
+    const match = result.match(pattern);
+    if (!match || match.index === undefined) continue;
+
+    const replacement = INJECTION + match[0];
+    result =
+      result.slice(0, match.index) +
+      replacement +
+      result.slice(match.index + match[0].length);
+
+    showDiff(
+      oldFile,
+      result,
+      replacement,
+      match.index,
+      match.index + match[0].length
+    );
+    patched = true;
+  }
+
+  if (!patched) {
+    debug('patch: sessionColor: failed to find app state init patterns');
+    return null;
+  }
+
+  return result;
+};