claude-code - 💡(How to fix) Fix [BUG] `claude --print -p` silently exits 143 after ~14 tool round-trips [1 comments, 2 participants]

### 1a. BSC_exit syscall (ktrace)

Captured via 'ktrace trace -b 1024 --ndjson' on macOS:




args[0] = 143 is the value passed to exit(2). The kernel's proc_exit
W-status confirms (0x8F00 = WIFEXITED true, WEXITSTATUS=143, no signal):




### 1b. CoreAnalytics atexit handler ran (unified log)

Apple's CoreAnalytics framework registers atexit() handlers; they
fire only on voluntary exit() (not on signal-kill):


2026-04-25 13:45:49.070740+1000
2026-04-25 13:45:49.070853+1000
2026-04-25 13:45:49.629451+1000


### 1c. claude's own --debug-file ends mid-stream

Last lines of `--debug all --debug-file ...` before exit. Note that
the very last log line is 'received first chunk' of an API request,
followed only by clean MCP/LSP teardown — no error, no warn, no
stall trigger:


2026-04-25T03:45:42.244Z [DEBUG] [API REQUEST] /v1/messages x-client-request-id=[ID_REDACTED] source=sdk
2026-04-25T03:45:44.690Z [DEBUG] Stream started - received first chunk
2026-04-25T03:45:44.700Z [DEBUG] [API REQUEST] /v1/messages x-client-request-id=[ID_REDACTED] source=sdk
2026-04-25T03:45:47.438Z [DEBUG] Stream started - received first chunk
2026-04-25T03:45:49.071Z [DEBUG] MCP server "pencil": Sending SIGINT to MCP server process
2026-04-25T03:45:49.072Z [DEBUG] LSP server manager shut down successfully
2026-04-25T03:45:49.073Z [DEBUG] Cleaned up session snapshot: /private/var/lib/claude/.claude/shell-snapshots/snapshot-zsh-1777088726273-dx1xg5.sh
2026-04-25T03:45:49.073Z [DEBUG] MCP server "pencil": STDIO connection closed after 33s (cleanly)
2026-04-25T03:45:49.073Z [DEBUG] MCP server "pencil": Cleared connection cache for reconnection
2026-04-25T03:45:49.124Z [DEBUG] MCP server "pencil": MCP server process exited cleanly


## Evidence 2: client-initiated disconnect on 14th /v1/messages

Captured via mitmproxy with HTTPS_PROXY injected post-sudo and
mitmproxy CA installed in system keychain.

Summary of all /v1/messages flows in one --print invocation:


FLOW #1: POST https://api.anthropic.com/v1/messages?beta=true
  request size:  303949 bytes
  response code: 200
  response size: 11247 bytes
FLOW #2: POST https://api.anthropic.com/v1/messages?beta=true
  request size:  309097 bytes
  response code: 200
  response size: 4458 bytes
FLOW #3: POST https://api.anthropic.com/v1/messages?beta=true
  request size:  309600 bytes
  response code: 200
  response size: 5223 bytes
FLOW #4: POST https://api.anthropic.com/v1/messages?beta=true
  request size:  312553 bytes
  response code: 200
  response size: 4329 bytes
FLOW #5: POST https://api.anthropic.com/v1/messages?beta=true
  request size:  317364 bytes
  response code: 200
  response size: 8050 bytes
FLOW #6: POST https://api.anthropic.com/v1/messages?beta=true
  request size:  321382 bytes
  response code: 200
  response size: 4131 bytes
FLOW #7: POST https://api.anthropic.com/v1/messages?beta=true
  request size:  339991 bytes
  response code: 200
  response size: 10382 bytes
FLOW #8: POST https://api.anthropic.com/v1/messages?beta=true
  request size:  355192 bytes
  response code: 200
  response size: 3562 bytes
FLOW #9: POST https://api.anthropic.com/v1/messages?beta=true
  request size:  366285 bytes
  response code: 200
  response size: 30736 bytes
FLOW #10: POST https://api.anthropic.com/v1/messages?beta=true
  request size:  368505 bytes
  response code: 200
  response size: 5534 bytes
FLOW #11: POST https://api.anthropic.com/v1/messages?beta=true
  request size:  369045 bytes
  response code: 200
  response size: 3995 bytes
FLOW #12: POST https://api.anthropic.com/v1/messages?beta=true
  request size:  378110 bytes
  response code: 200
  response size: 4725 bytes
FLOW #13: POST https://api.anthropic.com/v1/messages?beta=true
  request size:  387346 bytes
  response code: 200
  response size: 4389 bytes
FLOW #14: POST https://api.anthropic.com/v1/messages?beta=true
  request size:  389828 bytes
  response code: 200
  response size: 0 bytes


Notable points:

- All 14 requests received HTTP 200 + content-type: text/event-stream
- Flows 1-13: response body is a complete SSE stream ending with
  'event: message_stop'
- Flow 14: response body is 0 bytes. mitmproxy logs the disconnect
  source: '<< 200 OK (content missing) << Client disconnected.'
- Request body grows monotonically (304 KB -> 390 KB) as tool
  results are appended; this is normal conversation growth.

Mitmproxy log line proving the disconnect was client-initiated:


              << 200 OK (content missing)
 << Client disconnected.
--
              << 200 OK (content missing)
 << Client disconnected.
--
[IP]:55371: POST https://http-intake.logs.us5.datadoghq.com/api/v2/logs
 << Client disconnected.


## Evidence 3: stdin invocation does not hit this path

Same prompt content, only difference is delivery channel:


# Failing:
claude --print -p "$(cat prompt.txt)" < /dev/null    # exit 143

# Working:
claude --print < prompt.txt                              # exit 0
# (in test repro: 247s elapsed, did real work, committed)

---

claude --dangerously-skip-permissions --no-session-persistence \
       --model opus --print -p "$(cat large-prompt.txt)" < /dev/null
# elapsed: variable (7-130s observed across runs)
# exit code: 143
# stdout: empty
# stderr: empty