[henrychu04]

Problem

At work, Claude thread titles never generate. The workspace's claude is a managed startup script. In -p mode it prints === Claude Startup Script ===, a policy notice, an authentication check, === Launching Claude === and a tip on stdout, then runs the CLI. It shows no "Press Enter" prompt when stdin is piped, which was checked with echo hello | claude -p in the workspace.

ClaudeTextGeneration.ts decodes all of stdout as one JSON value, so every run fails with "Claude CLI returned unexpected output format." Titles swallow that error and keep the seed title. Review guides go through the same runner, which likely explains their "unexpected output format" report.

Change

• withoutLauncherPreamble drops plain-text lines before the first line that starts with { or [. It applies both to the success decode and to claudeErrorResult on a failed run. This matches what Drivers/ClaudeCli.ts already does for stream-json (096bf07).
• The change is marked Coder: and listed in the text-generation seam in docs/internals/coder-only.md.

Verification

• With a fake CLI printing the work banner before the JSON, scratch tests for the success and error paths failed without the fix and passed with it. The scratch tests are not committed.
• vp test run src/textGeneration: 52 passed.
• pnpm typecheck:server and vp fmt --check pass.
• Locally, the real Claude CLI (2.1.303) still generates titles.
• Still to do: a live title check at work once the helper is updated.

🤖 Generated with Claude Code