Allow launchThread to pass Codex approvalPolicy and sandboxPolicy (e.g. approval "never" + workspace-write) #21138

Context: T3 0.1.1-nightly.20261018.3285. orchestration.launchThread accepts runtimeMode/interactionMode but no
approvalPolicy or sandboxPolicy, and RuntimePolicyV2.resolve sets only runtimeMode, interactionMode and cwd.
Runtime modes map to fixed Codex settings:

• approval-required: untrusted / user / read-only
• auto-accept-edits: on-request / user / workspace-write
• auto: on-request / auto_review / workspace-write
• full-access: never / user / full access

Problem: Hosts that enforce /etc/codex/requirements.toml with allowed_approval_policies = ["never"] and
allowed_sandbox_modes = ["read-only","workspace-write"] (headless, fail-closed bot runners) cannot start any T3 turn
except full-access, which defeats the sandbox. Every non-full-access mode fails with "provider could not start this turn".

Ask: either (a) accept optional approvalPolicy and sandboxPolicy in launchThread input (or a server setting) and pass
them through to the Codex thread, validated against requirements.toml; or (b) add a runtime mode such as
"sandboxed-unattended" = approval never + workspace-write.

Expected: a command blocked by the sandbox fails back to the model and is never re-run unsandboxed.