docs: replace `sandbox create --sync` with `sandbox create --upload .`

[hasheddan]

Agent Diagnostic

the --sync flag doesn't work when running openshell sandbox create

→ Skill "build-from-issue"
Let me investigate the --sync flag issue in the sandbox create command first.
│ Explore Task — Investigate --sync flag in sandbox create
└ 16 toolcalls · 1m 14s
ctrl+x down view subagents
There is no --sync flag in the sandbox create command. Let me check what the user might be referring to — perhaps it's in docs, a separate subcommand, or a different flag name.
│ Explore Task — Search for sync flag references in docs and code
└ 9 toolcalls · 33.1s
ctrl+x down view subagents
The --sync flag does not exist in the codebase at all — neither in sandbox create nor anywhere else in the CLI.
Could you clarify what you're trying to do? It's possible you're thinking of:

• sandbox upload / sandbox download — subcommands for syncing files to/from a sandbox
• --upload flag on sandbox create — uploads files when creating a sandbox
  If --sync is something you expected based on documentation, a demo, or another source, it may not have been implemented yet. In that case, this would be a good candidate for a feature request or a spike to investigate what --sync should do and how it should work.
  What were you trying to accomplish with --sync?
  ▣ Build · Claude Sonnet 4.6 · 2m 9s

it is referenced in examples/sync-files.md

✱ Glob "examples/sync-files.md" (1 match)
→ Read examples/sync-files.md
Now I have full context. The examples/sync-files.md documents --sync as a flag for sandbox create, but the flag doesn't exist in the CLI implementation. This is a gap between docs and code.
Let me look at the existing --upload implementation to understand what --sync should do differently (if anything), then file an issue.
→ Read crates/openshell-cli/src/main.rs [offset=1014, limit=110]
The picture is clear. The examples/sync-files.md documents --sync as a flag that uploads git-tracked files before the command runs, but the CLI only has --upload which requires an explicit path argument. The --sync flag was never implemented.
The doc describes --sync as:

• No path argument required — automatically collects files via git ls-files
• Uploads to /sandbox before the command runs
  This is distinct from --upload which requires an explicit local path.
  This is a bug — missing feature with documentation already written.

Description

The examples/sync-files.md documentation references a --sync flag for openshell sandbox create, but it is not implemented. --upload . would be correct now.

Reproduction Steps

Run openshell sandbox create --sync.

Environment

• OS: Ubuntu 24.04
• Docker Version: Docker version 29.4.3, build 055a478
• OpenShell Version: openshell 0.0.39

Logs

$ openshell sandbox create --name demo --policy policy.yaml --sync -- opencode
error: unexpected argument '--sync' found

  tip: to pass '--sync' as a value, use '-- --sync'

Usage: openshell sandbox create --name <NAME> --policy <POLICY> [-- <COMMAND>...]

For more information, try '--help'.

Agent-First Checklist

• I pointed my agent at the repo and had it investigate this issue
• I loaded relevant skills (e.g., debug-openshell-cluster, debug-inference, openshell-cli)
• My agent could not resolve this — the diagnostic above explains why