fix(execd): validate request.cwd and return 400

[Pangjiping]

Summary

• validate request.cwd and return 400

Testing

• Not run (explain why)
• Unit tests
• Integration tests
• e2e / manual verification

Breaking Changes

• None
• Yes (describe impact and migration path)

Checklist

• Linked Issue or clearly described motivation
• Added/updated docs (if needed)
• Added/updated tests (if needed)
• Security impact considered
• Backward compatibility considered

[ninan-nn]

The new cwd validation looks good for RunCommandRequest and RunInSessionRequest. One thing I wanted to double-check is the behavior of the other cwd entrypoints: CreateContext currently auto-creates the target directory via os.MkdirAll, so it does not need to follow the same validation path. But CreateSession / CreatePTYSession do not create the directory for the caller; they just carry the provided cwd forward and will fail later when the process starts. If we want invalid request.cwd to be handled consistently at the API boundary, those entrypoints should be validated as well and return 400 instead of surfacing as a later runtime failure.

[Pangjiping]

CreatePTYSession

Great point! I previously overlooked the cwd setup in CreateSession and CreatePTYSession. I’ve now aligned the creation flow to set up cwd as well, following a fast-fail strategy.

[hittyt]

LGTM