[BUG] Bash tool fails on every command: "export: not valid in this context: SENTRY-TRACE" (zsh) — recurrence of #70416

Preflight Checklist

• [x] I have searched existing issues
• [x] This is a single bug report
• [x] I am using the latest version of Claude Code

Summary

Every Bash tool invocation fails before the command runs with:

zsh:export:62: not valid in this context: SENTRY-TRACE
exit code 1

This is the same bug as #70416 (which was auto-closed as stale / not_planned by the bot on 2026-08-05 without ever being triaged). Filing a fresh report since it is still occurring on a current version. In my case the failing builtin is export (the original report saw declare), but the root cause is identical.

Root cause (confirmed, same as #70416)

The environment handed to the Bash tool contains an env var whose name has a hyphen: SENTRY-TRACE — Sentry's sentry-trace distributed-tracing header, materialized as an env var by the app's instrumentation. When Claude Code reconstructs that environment for the subshell, it emits export SENTRY-TRACE=… / declare SENTRY-TRACE=…. zsh parses export/declare/typeset arguments as assignments at parse time, and SENTRY-TRACE is not a valid POSIX shell identifier, so the line fails to parse and aborts the entire command preamble → exit 1 before any command runs. bash tolerates this (it ignores the invalid name); zsh fails hard.

Evidence it's the app, not my shell

• ~/.zshrc line 62 is blank; ~/.zshenv, ~/.zprofile, ~/.zlogin do not exist on this machine.
• I have nothing Sentry-related installed or configured — no SDK, no config, no such env var in a normal terminal.
• The variable exists only in shells spawned by the app. SENTRY-TRACE is a per-request HTTP tracing header, not something present in a user environment.

Expected behavior

Claude Code should not feed env var names that aren't valid POSIX shell identifiers through export/declare/typeset. When generating the shell preamble/snapshot, skip or sanitize names that don't match [A-Za-z_][A-Za-z0-9_]* (or encode them), so a single non-identifier var name can't abort every command.

Steps to Reproduce

1. Launch Claude Code via Claude Desktop (macOS).
2. Start a session and prompt Claude to run any Bash command (e.g. echo hello).
3. Every command fails with zsh:export:…: not valid in this context: SENTRY-TRACE before running.

Note: as in #70416, this appears intermittently — most sessions are fine, but once it starts it persists across new sessions and Claude Desktop restarts.

Environment

• Launched via: Claude Desktop
• OS: macOS (Darwin 24.6.0)
• Shell: zsh
• Model: Opus 4.8
• Same symptom and root cause as #70416

Related

• #70416 (original report, closed stale — not fixed)
• #7490 (feature request: configurable Bash-tool shell; switching to bash is the current workaround)