/go/cmd/dolt/cli: only emit backspace characters in a tty

[coffeegoddd]

The CLI's progress spinners (dolt push, pull, fetch, assist, and import/sql progress output) redraw themselves in place by writing backspace control characters. This was done unconditionally, with no check for whether output was going to a terminal.

When stdout/stderr is captured to a file or pipe — a script, a CI job, dolt push > push.log 2>&1 — those backspaces become literal bytes in the log instead of cursor movements. Rendering the log then "erases" the surrounding text. The worst case: an error is printed while the spinner is active, and the spinner's trailing backspaces overwrite the error text, so the captured log looks empty exactly when something went wrong.

This PR fixes this so that TTY is detected and redraw is gated on it.

[coffeegoddd]

@coffeegoddd DOLT

read_tests	from_latency	to_latency	percent_change
covering_index_scan	2.3	2.3	0.0
groupby_scan	144.97	142.39	-1.78
index_join	1.93	1.89	-2.07
index_join_scan	1.32	1.32	0.0
index_scan	215.44	215.44	0.0
oltp_point_select	0.25	0.25	0.0
oltp_read_only	5.0	5.0	0.0
select_random_points	0.5	0.51	2.0
select_random_ranges	0.64	0.64	0.0
table_scan	200.47	200.47	0.0
types_table_scan	458.96	458.96	0.0

write_tests	from_latency	to_latency	percent_change
oltp_delete_insert	6.09	6.09	0.0
oltp_insert	3.13	3.13	0.0
oltp_read_write	11.24	11.24	0.0
oltp_update_index	3.3	3.3	0.0
oltp_update_non_index	2.97	3.02	1.68
oltp_write_only	6.21	6.21	0.0
types_delete_insert	6.79	6.79	0.0

[coffeegoddd]

@coffeegoddd DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
2486a0d	ok	5937471

version	total_tests
2486a0d	5937471

correctness_percentage
100.0

[coffeegoddd]

@coffeegoddd DOLT

test_name	from_latency_p95	to_latency_p95	percent_change
tpcc-scale-factor-1	43.39	45.79	5.53

test_name	from_server_name	from_server_version	from_tps	to_server_name	to_server_version	to_tps	percent_change
tpcc-scale-factor-1	dolt	0e9a297	53.1	dolt	782d3a2	52.79	-0.58

[Copilot]

Pull request overview

Updates Dolt’s CLI progress spinner redraw behavior to avoid emitting backspace control characters when output isn’t attached to a terminal, preventing captured logs (CI, pipes, redirected output) from being visually “erased” by control bytes.

Changes:

• Detects whether output is a TTY and gates DeleteAndPrint’s backspace-based redraw behavior on that.
• Adds unit tests asserting no backspaces are emitted when output is treated as non-TTY, and that captured error output isn’t corrupted.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
go/cmd/dolt/cli/stdio.go	Adds TTY detection and skips emitting backspaces in DeleteAndPrint when not running in a terminal.
go/cmd/dolt/cli/stdio_test.go	Adds tests for non-TTY behavior and ensures spinner output doesn’t corrupt captured error logs.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[coffeegoddd]

@coffeegoddd DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
782d3a2	ok	5937471

version	total_tests
782d3a2	5937471

correctness_percentage
100.0