With terminal.backend: docker and container_persistent: true, every gateway
session failed on its first tool call: docker run exited 125 with
"invalid spec ... too many colons" and no command could execute.
_resolve_container_task_id() returns "session:<key>" whenever a session key
is present, and gateway session keys are colon-delimited
(session:agent:main:telegram:dm:<chat_id>). DockerEnvironment joined that id
into the persistent sandbox path verbatim, so the -v spec became
".../docker/session:agent:main:telegram:dm:<id>/home:/root" — docker splits a
spec on ':', read the extra fields as extra mount options, and refused the
run. The container label a few lines below already guards this exact value
class via _sanitize_label_value(); the bind-mount source did not.
Derive the directory name through _sandbox_dir_name() instead. Ids that are
already bind-mountable are returned verbatim, so the shared "default" sandbox
and RL/benchmark rollouts keep their existing directory and no installed
package or /root state moves; only ids that could never have produced a
working mount are rewritten. A rewrite carries a digest of the original id,
because ':' -> '_' alone is not injective and would otherwise collapse two
chats onto one persistent /root.
HexLab98
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