No-Man's-Land Failures in Agent Pipelines

Today we hit a class of failures that are easy to misdiagnose: not prompt bugs, not repository logic bugs, and not deterministic workflow bugs. They happen in the integration gap between GitHub APIs, hosted runner networking, and third-party artifact delivery.

What Happened

We observed two concrete patterns:

• Dispatch returned HTTP 500 but still started downstream.
  An intake workflow failed on gh workflow run ... with a server error, yet the routing workflow actually started and completed. The upstream run looked failed while the pipeline still moved forward.

• Phase execution failed during tool install with HTTP 502.
  A phase run failed while installing GitHub Copilot CLI because the release asset download returned 502. A rerun succeeded without workflow changes.

These are classic “no-man’s-land” failures: infrastructure or platform edge conditions where control-plane state and CLI/API responses can briefly disagree.

Why This Matters

If you treat every failure as deterministic logic failure, you waste time debugging the wrong layer. In multi-stage agent pipelines, transient infra errors can also block the next phase even when issue state is otherwise correct.

Practical Response

• Treat 5xx in dispatch/install steps as potentially transient.
• Keep dispatchers idempotent so reruns are safe.
• Verify downstream run creation separately before assuming dispatch really failed.
• Leave clear issue comments with run links so humans can quickly distinguish logic failures from platform flakiness.

Hardening to Avoid Heavy Deploy Paths

Transient failures are unavoidable, but expensive execution can be reduced with better workflow boundaries.

• Put label/state eligibility gates first, before token checks, model checks, CLI installs, or container startup.
• Treat comment-triggered workflows as untrusted entry points and short-circuit early unless lifecycle labels and issue state are valid.
• Keep heavy agent phases behind explicit dispatch from validated dispatcher jobs, not directly from broad events.
• Record gating decisions in lightweight comments so operators can tell “blocked by policy” from “failed during execution.”

Agentic systems are only as reliable as their orchestration edges. “No-man’s-land” failures are normal in production; what matters is designing the workflow so they are recoverable.