swebenchmultimodal: diegomura/react-pdf-1178 consistently fails runtime init across models and runs

Summary

The diegomura__react-pdf-1178 instance in swebenchmultimodal-dev consistently fails
runtime init across multiple models and runs, even after the runtime-api / sdk fix for
#523 (OpenHands/software-agent-sdk#2656). This is deterministic, not transient: every
attempt in every run fails with the same 502→503 runtime init pattern.

Two sibling instances (react-pdf-1280, react-pdf-1552) also fail frequently but
intermittently — they sometimes succeed on retry.

Evidence

Run 1: 2026-04-06, opus4.6 + sonnet4.5 (evaluation run 24040981135)

Model	Job	react-pdf-1178	react-pdf-1280	react-pdf-1552
claude-4.6-opus	eval-24040981135-claude-4-6	❌ failed 4x	✅ (on retry)	✅ (on retry)
claude-sonnet-4-5-20250929	eval-24040981135-claude-son	❌ failed 4x	❌ failed 4x	❌ failed 4x

Run 2: 2026-04-04, gemini-3.1 (jobs eval-23983344719-gemini-3-1, eval-23968391657-gemini-3-1)

react-pdf-1178 failed on both runs (Datadog logs confirm failed after 4 attempts).

So: 3 distinct models × at least 3 eval runs over 3 days — react-pdf-1178 failed every
time.

Error pattern

From kube_job:eval-24040981135-claude-4-6 (Opus), instance diegomura__react-pdf-1178:

2026-04-06 19:43:17 ERROR  HTTP request failed (502 Bad Gateway): ...
  url: https://vqjiqojpacbxmmaw.eval-runtime.all-hands.dev/api/acp/conversations/9e52265f-...
2026-04-06 19:43:19 ERROR  HTTP request failed (503 Service Unavailable): ...
... (20+ seconds of 1/s polling with 503s) ...
2026-04-06 19:43:37 WARNING [worker] runtime init failure instance=diegomura__react-pdf-1178
    attempt=1 retry=1 runtime_id=vqjiqojpacbxmmaw
    error=Conversation run failed ...: Remote conversation ended with error
... (3 more attempts with different runtime_ids, same pattern) ...
2026-04-06 21:59:16 ERROR  [worker] Instance diegomura__react-pdf-1178 failed after 4 attempts.

Each attempt spins up a fresh runtime pod (new runtime_id), hits 502/503 on /api/acp/conversations/..., polls for 20+ seconds, gives up, and moves on. After 4 such attempts the
worker marks it failed.

Suspected root cause

Likely the same family as OpenHands/benchmarks#352 (still OPEN): the
react-pdf-1178 image is slow to boot (or has a startup issue), the agent-server startup
probe on port 60000 fails, the pod is force-stopped, and the client sees 502/503 on
/api/acp/conversations/....

Unlike #523 (which was about large wp-calypso/p5.js images and was fixed by sdk#2656),
this one is narrower — a single react-pdf instance that consistently fails. Possibilities:

1. Broken image: react-pdf-1178 Dockerfile produces an image that never becomes
   healthy (e.g. node version regression — see root_cause_acp_node.md in memory; Node
   v12–v14 crashes claude-agent-acp).
2. Unreasonable startup time: image starts but takes longer than the startup probe
   window.
3. ACP-specific init bug: the instance repo requires setup that ACP agents trip on.

Repro

/trigger-benchmarks swebenchmultimodal agent_type=acp-claude model_ids=claude-4.6-opus \
  eval_limit=500 reason="repro react-pdf-1178 failure"

Expected: react-pdf-1178 fails after 4 runtime init attempts.

Proposed next steps

1. Inspect the SWE-bench-M image for diegomura/react-pdf-1178 — manually pull it,
   start agent-server in it, verify /server_info on port 60000 comes up.
2. Check if Node.js is old in that image (see known ACP/Node issue); force Node 22
   install if missing.
3. If image is fundamentally broken, consider blacklisting the 3 flaky instances
   (1178, 1280, 1552) or filing upstream with SWE-bench-M.
4. Add a fast-fail path in the runtime init polling: if 5xx persists for >5s on the
   first attempt, abort that attempt instead of polling for 20s (saves ~60s per failed
   instance — currently ~90s of wall-clock wasted on retries).

References

• Related (closed): #523 — broader wp-calypso/p5.js runtime-api failures (fixed by
  software-agent-sdk#2656)
• Related (open): #352 — runtime pod startup probe 503s
• Eval run: evaluation workflow 24040981135 (correlation id E698D406)
• Datadog: https://app.datadoghq.com/logs?query=kube_job%3Aeval-24040981135-claude-4-6

Start by pulling the SWE-bench-M image for diegomura/react-pdf-1178 and launching agent-server, then check whether /server_info becomes available on port 60000. Inspect the image's Node.js version and compare its startup behavior with the related runtime failures in #352. Done means identifying the failure cause and documenting or implementing a verified fix, blacklist decision, or targeted runtime change.