GeezerVison

Problem

The Claude Code scaffolds (sync-claude-code, default-claude-code, temporal-claude-code) and their tutorial copies (00_sync/060, 10_async/00_base/130, 10_async/10_temporal/140) share two bugs in how they read the CLI.

1. Lines over 64 KiB abort the turn. stdout is read through asyncio's StreamReader with its default 64 KiB limit (async for chunk in proc.stdout is readline() underneath). Claude Code writes one JSON line per event, so a tool_result that echoes a large file read is a single line far past 64 KiB. readline() then raises ValueError: Separator is found, but chunk is longer than limit, and the turn fails before its result event. The same class of bug was already fixed for agentex agents run (SUBPROCESS_STREAM_LIMIT in cli_utils.py).

2. Cancellation can hang. Cleanup sends SIGTERM and then awaits proc.wait() with no bound. A CLI that ignores or delays SIGTERM blocks request cancellation (sync/async ACP) or Temporal activity cancellation indefinitely.

Fix

In each of the six files:

• read stdout with limit=STDOUT_LINE_LIMIT (8 MiB);
• after SIGTERM, wait at most TERMINATE_TIMEOUT_SECONDS (5 s), then SIGKILL;
• document both in _spawn_claude's docstring.

Nothing else changes. The Codex templates read with read(4096) and use kill(), so neither bug applies to them. The Gemini CLI templates in #516 got the same treatment.

Verification

I put a fake claude on PATH and drove _spawn_claude() from the rendered sync and Temporal templates.

• tests/lib/cli/test_init_templates.py: 26 passed.
• Each tutorial's tests/test_agent_offline.py: 7, 5 and 5 passed.
• ruff check is clean on the tutorial files, and all three compile.

Confidence Score: 5/5

The PR appears safe to merge; the earlier missing-test concern is addressed.

What we checked:

• Subprocess command injection: No. The subprocess receives a fixed command without a shell, and the prompt is written to stdin. The new argument only sets the stdout read limit.

Summary

Claude Code scaffolds now read stream-JSON lines up to 8 MiB and stop lingering CLI processes after a five-second grace period. The updates cover the generated templates and tutorial copies, with an offline subprocess test for both paths.

• Large tool_result lines can reach the turn without hitting asyncio’s default line limit.
• Early shutdown sends SIGTERM, then SIGKILL if the CLI is still running after five seconds.

_{Reviews (2) · Last reviewed commit: "test(templates): run the Claude Code sca..."}