Agent step dies instantly when the task text starts with '--' (Garden runs for #523/#524)

[khaliqgant]

What happened

Two Flows Software Garden runs failed at their first agent step within a second, with 0 tokens:

Issue	Run	Result
#524 "--reuse-from is refused when an already-reused step's model is unavailable…"	9029a74d-5d75-5efc-a3c1-94c5529b6b82	agent-3 worker_error after 526 ms, exit 1, 0 tokens
#523 "--reuse-from silently reuses steps whose real output is on disk…"	cbf5aced-edc7-5471-8cfc-e29f83b19131	agent-3 worker_error after 585 ms, exit 1, 0 tokens

The run log's step.completed for agent-3 records "cli":"agent","model":"claude-opus-5", and the step's stderr_tail is a fragment of the issue body (the task text), not a CLI error message. Other Flows Garden runs dispatched in the same window with ordinary titles (e.g. #473, #502) ran normally and opened PRs.

Hypothesis (unconfirmed)

Both failing issues are the only ones whose title begins with -- (--reuse-from …). The task text appears to reach the agent CLI as a command-line argument, so a leading --… is parsed as an option and the CLI exits immediately. If so, any ticket whose title starts with -/-- kills the run.

Also worth checking: the step records cli: "agent" where successful runs of the same Garden record claude; confirm that is just a label.

Ask

• Reproduce: run an agent step whose task begins with --reuse-from … through the same worker path the Cloud runtime uses.
• Fix: never pass task text as a positional argv value that can be read as an option (pass it via stdin/a file, or after a -- end-of-options separator, whichever the CLI supports), for every supported agent CLI.
• Regression test with a task starting with -- and with -.
• Then the two issues above can be re-dispatched to the Garden.