* fix(sandbox): enforce AIO shell command timeouts
Map Sandbox.execute_command(timeout=T) onto the AIO legacy shell as a server-side hard_timeout=T plus a bounded host request (ceil(T+5)s, max_retries=0), preserve and render the upstream status (hard_timeout -> terminated + Exit Code: 124; no_change_timeout -> may still be running), keep no_change_timeout from preempting hard_timeout, and restrict ErrorObservation replay to completed results.
* fix(sandbox): contain ambiguous AIO command outcomes
Treat a transport timeout and statuses terminated/no_change_timeout/unknown as ambiguous: never replay the current command, fence the scoped or recovery session generation with bounded best-effort cleanup, and never adopt a replacement session for those statuses. hard_timeout and completed keep the session reusable. Align the env-bearing bash.exec path with the same contract and make its retry result authoritative.
* fix(sandbox): wire AIO command timeout from provider config
Restore bash_tool's non-local behaviour (other providers keep their own defaults) and let AioSandboxProvider read sandbox.bash_command_timeout as the sandbox's default_command_timeout at every construction site, with explicit per-call timeouts still winning. Widen the config field to float with allow_inf_nan=False and read the provider value with the module fallback so partial-config providers keep working.
* docs(sandbox): document AIO command timeout semantics
Document the provider-scoped deadline (LocalSandbox/AioSandbox/OpenSandbox wire it; other providers keep their defaults), the semver-vs-frozen-:latest image behaviour, the no-replay guarantees, and trim the sandbox guidance back under its size budget.
* docs(sandbox): scope the wedge-resistance claim to command requests
willem-bd's review on #5634 reproduced that list_dir and both create_session call sites still make unbounded SDK requests while holding the same sandbox lock, so the guide must not read as if every AIO request is bounded. State that the bounded T+5s host wait applies to command requests and name session-creation and file/list RPCs as not covered; bounding those remains a separate operation-deadline/control-plane follow-up.
* fix(sandbox): make list_dir honor the shell generation fence
list_dir previously always targeted the implicit persistent shell, so after an ambiguous command outcome fenced that generation (#5634) a listing could re-enter it. Route default-shell target selection through _ensure_default_shell_session_id so both execute_command and list_dir reuse the explicit recovery session, creating one only when the implicit shell is fenced. No list_dir deadline, hard_timeout, request budget, retry, or status semantics are added; those remain scoped to #5644.
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