[BUG] Claude in Chrome: tabs_context_mcp fails with 'Grouping is not supported by tabs in this window' on Chrome 148 (Windows)

Environment

• Chrome version: 148.0.7778.179 (Windows 11 Pro)
• Extension version: Claude v1.0.74 (Profile 2, fcoeoabgfenejglbffodgkkbkcdhcgfn)
• OS: Windows 11 Pro 10.0.26200
• Claude Code version: 2.1.154

Bug Description

Every call to tabs_context_mcp (with or without createIfEmpty: true) fails with:

Failed to query tabs: Grouping is not supported by tabs in this window.

This makes ALL Chrome MCP browser tools unusable since tabs_context_mcp is required first.

Root Cause (traced via extension source)

In mcpPermissions-O6s_WAiZ.js, getOrCreateMcpTabContext creates a new window:

const e = await chrome.windows.create({url:"chrome://newtab", focused:true, type:"normal"});
const t = e?.tabs?.[0]?.id;
const r = await this.createGroup(t); // calls chrome.tabs.group({tabIds:[t]})

createGroup() retries chrome.tabs.group({tabIds:[newTabId]}) 3 times with 100ms delay, then throws. The Chrome API consistently returns "Grouping is not supported by tabs in this window" for the chrome://newtab tab in the newly created window.

Hypothesis: Chrome 148 does not allow chrome://newtab tabs to be grouped via extension API, unlike earlier Chrome versions. Using about:blank instead of chrome://newtab in chrome.windows.create() would likely fix this.

What Was Ruled Out

• ✅ Extension permissions — tabGroups present in manifest.json
• ✅ Chrome enterprise/group policies — none (HKLM + HKCU empty)
• ✅ Chrome flags (enabled_labs_experiments) — empty
• ✅ Saved tab groups in Profile preferences — not found
• ✅ Profile mismatch — extension in correct profile (last_used)
• ✅ Extension storage corruption — wiped Local Extension Settings, same error
• ✅ TabGroupsSaved feature — disabled via --disable-features=TabGroupsSaved, same error
• ✅ Two different paired browsers both fail identically

Steps to Reproduce

1. Chrome 148.0.7778.179 on Windows 11
2. Claude extension v1.0.74 installed and paired
3. Call tabs_context_mcp with createIfEmpty: true
4. Result: Failed to query tabs: Grouping is not supported by tabs in this window.

Suggested Fix

Change chrome.windows.create({url:"chrome://newtab"...}) to use about:blank instead of chrome://newtab in getOrCreateMcpTabContext. The chrome://newtab URL may trigger API restrictions in Chrome 148 that prevent tab grouping.

Impact

All Chrome MCP browser automation is blocked on Chrome 148 / Windows. Workaround: use Playwright MCP for non-authenticated browser tasks.