[BUG] Auto mode never appears in VS Code extension picker — server-side gate (tengu_auto_mode_state) never delivered for client_type claude-vscode

Summary

Auto mode never appears in the VS Code extension's permission-mode picker (Shift+Tab menu), even though the account is enrolled in the broader Auto mode rollout and claude --permission-mode auto works correctly from the terminal CLI on the same account/machine. This reproduces the exact symptom already reported and closed-stale in #61282, #60086, and #44941 (Linux, Windows x2) — this report adds code-level root-cause evidence from reading the compiled extension bundle directly, isolating it to a specific server-side feature gate.

Environment

• Claude Code VS Code extension: 2.1.220 (confirmed current via marketplace at time of testing — not a stale-extension issue)
• OS: macOS
• Terminal CLI: same version family, works correctly (claude --permission-mode auto succeeds every time)

What we found

The extension's webview picker-building function (Ti() in the bundled webview/index.js) conditionally includes "auto" in the mode list based on a live, server-pushed field:

experimentGates.tengu_auto_mode_state === "enabled" | "opt-in"

This field is delivered via JSON-RPC from the spawned CLI subprocess at session start — it is never read from any local file, so no claudeCode.* VS Code setting, environment variable, or ~/.claude/settings.json key can force it. We confirmed none of those exist as an override.

Inspecting the account's live gate cache (~/.claude.json) shows:

• tengu_auto_mode_config: "enabled" — the account is enrolled in the broader Auto mode feature.
• tengu_auto_mode_state — missing entirely, not explicitly set to a disabled value. It's simply never delivered.

The extension reports client_type: "claude-vscode" to the backend (vs. plain terminal sessions). Combined with the terminal working fine on the identical account, this strongly suggests a rollout gate that keys off client_type and has not been enabled for the VS Code surface, rather than an account-level eligibility issue or a bug in the extension's own rendering logic.

What we ruled out (all tested directly, not assumed)

• Extension staleness — confirmed on latest marketplace version (2.1.220), MD5-identical bundled CLI vs. system CLI
• Any claudeCode.* VS Code setting exposing this — none exists
• Any environment variable override — none found
• Stale local cache — a full VS Code quit + reopen does not refresh the gate (tested)
• skipAutoPermissionPrompt / other local permission flags — no effect
• Account/model ineligibility — ruled out by the terminal CLI working correctly on the same account

Expected behavior

Auto mode should appear in the VS Code picker for any account where tengu_auto_mode_config is enabled, matching terminal CLI behavior on the same account.

Ask

Given this reproduces across at least 3 prior closed reports on different platforms over time, could someone confirm whether tengu_auto_mode_state rollout is specifically gated per client_type, and if so, get claude-vscode included? Happy to provide additional local diagnostics if useful.