Decision: Enforce 120s minimum timeout for sandbox creation

Status: implemented Implemented: 2026-09-28

Problem

Users who set http_timeout = 30 in ~/.abx/config.toml (a reasonable value for most API calls) unknowingly override the cold-start protection on sandbox creation. FC sandbox cold starts can take 60–90s for image pulls, so a 30s timeout causes abx create to fail silently with a generic timeout error, leaving users confused about whether the template or the platform is broken.

Decision

Apply a floor of 120 seconds to the HTTP timeout used specifically for sandbox creation requests:

create_timeout = max(configured_timeout, 120.0)

• The user's http_timeout config is respected for all other operations.
• For create only, the effective timeout is max(user_value, 120).
• If a user explicitly passes --timeout 180, that value is used (it exceeds the floor).

Rationale for 120s

• Observed cold starts: 60–90s (image pull + container init).
• 120s provides ~30s headroom above worst-case observed cold starts.
• Matches the platform's own gateway timeout window.

Alternatives considered

• Warn but don't override — users would still hit the timeout and need to manually retry with a longer value. Poor UX. Rejected.
• Set a higher floor (300s) — unnecessarily long for warm starts; users would perceive the CLI as sluggish if creation fails for other reasons. Rejected.

Files changed

• src/agent_sandbox/cli/commands/sandbox.py — create command timeout logic

Acceptance criteria

• ✅ abx create with http_timeout=30 uses 120s for the creation request
• ✅ abx create --timeout 180 uses 180s (exceeds floor)
• ✅ Other commands still respect the configured http_timeout as-is