diff --git a/src/patches/index.ts b/src/patches/index.ts
index a1c69861..2e088007 100644
--- a/src/patches/index.ts
+++ b/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',
@@ -663,6 +671,9 @@ export const applyCustomization = async (
         ),
       condition: config.settings.misc?.statuslineThrottleMs != null,
     },
+    'session-color': {
+      fn: c => writeSessionColor(c),
+    },
     // Misc Configurable
     'patches-applied-indication': {
       fn: c =>
diff --git a/src/patches/sessionColor.test.ts b/src/patches/sessionColor.test.ts
new file mode 100644
index 00000000..41488a0e
--- /dev/null
+++ b/src/patches/sessionColor.test.ts
@@ -0,0 +1,96 @@
+import { describe, it, expect } from 'vitest';
+import { writeSessionColor, patchSaveAgentColor } from './sessionColor';
+
+const makeSaveAgentColor = () =>
+  ';async function Mr$(H,$,q){let K=q??sT(H);' +
+  'if(Hv(K,{type:"agent-color",agentColor:$,sessionId:H}),H===V$())' +
+  'WA().currentSessionAgentColor=$;c("tengu_agent_color_set",{})}';
+
+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();
+
+const makeFullFile = () => makeBoth() + makeSaveAgentColor();
+
+describe('sessionColor', () => {
+  describe('writeSessionColor', () => {
+    it('should inject into CLI initialState and patch saveAgentColor', () => {
+      const result = writeSessionColor(makeFullFile());
+      expect(result).not.toBeNull();
+      expect(result).toContain('TWEAKCC_SESSION_COLOR');
+      expect(result).toContain('{name:"",color:__c}');
+      expect(result).toContain('__tweakccSaveAgentColor');
+    });
+
+    it('should inject into default app state', () => {
+      const input = makeDefaultState() + makeSaveAgentColor();
+      const result = writeSessionColor(input);
+      expect(result).not.toBeNull();
+      expect(result).toContain('TWEAKCC_SESSION_COLOR');
+    });
+
+    it('should patch both initialState locations', () => {
+      const result = writeSessionColor(makeFullFile())!;
+      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(makeFullFile())!;
+      expect(result).toContain('.includes(__c)');
+      expect(result).toContain('"green"');
+      expect(result).toContain('"cyan"');
+    });
+
+    it('should be idempotent', () => {
+      const first = writeSessionColor(makeFullFile())!;
+      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();
+    });
+
+    it('should schedule color save via queueMicrotask', () => {
+      const result = writeSessionColor(makeFullFile())!;
+      expect(result).toContain('queueMicrotask');
+      expect(result).toContain('__tweakccSaveAgentColor');
+    });
+
+    it('should expose saveAgentColor on globalThis', () => {
+      const result = writeSessionColor(makeFullFile())!;
+      expect(result).toContain(
+        'globalThis.__tweakccSaveAgentColor=(c)=>Mr$(V$(),c)'
+      );
+    });
+  });
+
+  describe('patchSaveAgentColor', () => {
+    it('should find and patch saveAgentColor', () => {
+      const result = patchSaveAgentColor(makeSaveAgentColor());
+      expect(result).not.toBeNull();
+      expect(result).toContain('globalThis.__tweakccSaveAgentColor');
+    });
+
+    it('should return null when pattern not found', () => {
+      const result = patchSaveAgentColor('no match here');
+      expect(result).toBeNull();
+    });
+
+    it('should preserve original function', () => {
+      const result = patchSaveAgentColor(makeSaveAgentColor())!;
+      expect(result).toContain('async function Mr$');
+      expect(result).toContain('type:"agent-color"');
+    });
+  });
+});
diff --git a/src/patches/sessionColor.ts b/src/patches/sessionColor.ts
new file mode 100644
index 00000000..89c8e783
--- /dev/null
+++ b/src/patches/sessionColor.ts
@@ -0,0 +1,118 @@
+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;` +
+  `if(!__c||!${JSON.stringify(VALID_COLORS)}.includes(__c))return void 0;` +
+  `queueMicrotask(()=>{` +
+  `if(globalThis.__tweakccSaveAgentColor)globalThis.__tweakccSaveAgentColor(__c)` +
+  `});` +
+  `return{name:"",color:__c}` +
+  `})()`;
+
+export const writeSessionColor = (oldFile: string): string | null => {
+  if (
+    oldFile.includes(
+      'standaloneAgentContext:(()=>{let __c=process.env.TWEAKCC_SESSION_COLOR;'
+    )
+  ) {
+    return oldFile;
+  }
+
+  const patterns = [
+    /,activeOverlays:new Set,fastMode:[$\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 prePatch = result;
+    const replacement = INJECTION + match[0];
+    result =
+      prePatch.slice(0, match.index) +
+      replacement +
+      prePatch.slice(match.index + match[0].length);
+
+    showDiff(
+      prePatch,
+      result,
+      INJECTION,
+      match.index,
+      match.index + match[0].length
+    );
+    patched = true;
+  }
+
+  if (!patched) {
+    debug('patch: sessionColor: failed to find app state init patterns');
+    return null;
+  }
+
+  const saveColorResult = patchSaveAgentColor(result);
+  if (!saveColorResult) {
+    debug('patch: sessionColor: failed to patch saveAgentColor');
+    return null;
+  }
+
+  return saveColorResult;
+};
+
+export const patchSaveAgentColor = (oldFile: string): string | null => {
+  const pattern = new RegExp(
+    '([,;{}])' +
+      '(async function ([$\\w]+)' +
+      '\\(([$\\w]+),([$\\w]+),([$\\w]+)\\)' +
+      '\\{let [$\\w]+=\\6\\?\\?[$\\w]+\\(\\4\\);' +
+      'if\\([$\\w]+\\([$\\w]+,' +
+      '\\{type:"agent-color",agentColor:\\5,sessionId:\\4\\}\\),' +
+      '\\4===([$\\w]+)\\(\\)\\))'
+  );
+  const match = oldFile.match(pattern);
+  if (!match || match.index === undefined) {
+    return null;
+  }
+
+  const delimiter = match[1];
+  const funcBody = match[2];
+  const funcName = match[3];
+  const getSessionIdName = match[7];
+
+  const injection =
+    `globalThis.__tweakccSaveAgentColor=` +
+    `(c)=>${funcName}(${getSessionIdName}(),c);`;
+
+  const replacement = `${delimiter}${injection}${funcBody}`;
+
+  const result =
+    oldFile.slice(0, match.index) +
+    replacement +
+    oldFile.slice(match.index + match[0].length);
+
+  showDiff(
+    oldFile,
+    result,
+    injection,
+    match.index,
+    match.index + match[0].length
+  );
+
+  return result;
+};