Cleaner stdout when not in TTY

[stephenlf]

Problem

Many long-running sf commands use a beautiful, dynamic output for streaming live updates to the user's TTY. This is fantastic UX, as long as the user TTY is the final output.

However, trying to pipe or redirect that output reveals a mess of control characters that clogs up downstream pipelines.

See raw output

$ sf project deploy start > out.log
$ cat out.log

... output truncated ...

 ───────────── Validating Deployment ─────────────


 ◼ Preparing
 ◼ Waiting for the org to respond
 ◼ Deploying Metadata
 ◼ Running Tests
 ◼ Updating Source Tracking
 ◼ Done

 Status: ⠁
 Elapsed Time: 0ms

ESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[G
 ───────────── Validating Deployment ─────────────


 ⣾ Preparing 3ms
 ◼ Waiting for the org to respond
 ◼ Deploying Metadata
 ◼ Running Tests
 ◼ Updating Source Tracking
 ◼ Done

 Status: ⠁
 Deploy ID: 0AfO200000XVmdFKAT
 Target Org: sfunk@enrollmentmanagementservices.com.ems.sandbox
 Elapsed Time: 27ms

ESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KES
ESC[1AESC[2KESC[G
 ───────────── Validating Deployment ─────────────


 ⣾ Preparing 37ms
 ◼ Waiting for the org to respond
 ◼ Deploying Metadata
 ◼ Running Tests
 ◼ Updating Source Tracking
 ◼ Done

 Status: ⠁
 Deploy ID: 0AfO200000XVmdFKAT
 Target Org: sfunk@enrollmentmanagementservices.com.ems.sandbox
 Elapsed Time: 59ms

ESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KESC[1AESC[2KES
ESC[1AESC[2KESC[G

... output truncated ...

Recommended Solution

Use Node's tty.isatty function to determine whether the output environment supports streaming responses. If it does not, do not send dynamic outputs. Only write the final result to the screen.

Mitigations/Workarounds

• Set the SF_CONTENT_TYPE=JSON environment variable. This is undesirable because I want a human-readable snapshot of the final result for downstream processing, not a JSON dump.
• Use hacks to process stdout as it streams in. (Let me know if you find a function that works!
• Leverage stdout vs stdin to selectively render non-TTY and TTY outputs. This works for failures, but will always come up empty with successes.

Related Discussions

• Improved CLI for optimum agentic use (incl. reduced token consumption) #3542 shows that this issue is exacerbated by Agent use. These junk control characters quick gunk up agent context windows.
• Implement TTY detection so progress bar is not shown unless in a TTY environment #2699 shows an instance where this problem was solved for a subset of the CLI.