openai/symphony
Symphony turns project work into isolated, autonomous implementation runs, allowing teams to manage work instead of supervising coding agents.
GitHub 
12K
lines of main code
57 files
13K
lines of test code
30 files
3.8K
lines of other code
31 files
<1y
age
217 days
100%
main code touched
1 year (12K LOC)
ABCDE
ease of change
for people*
ABCDE
ease of change
for AI*
11K
ex
0.5K
py
0.4K
css
0.1K
exs
0.01K
toml
30 days 2026
+2
-2
+8.5K
-3.4K
2

154

2

32

1

7

1

6

2026
Rule-of-thumb estimates

Rebuild value

to rebuild
rebuild value

Maintenance effort

per year to maintain
maintenance cost per year
Rules of thumb, not measurements: one man-year rebuilds about 10,000 lines of main code (design, testing and coordination included), and keeping a code base alive takes about 15% of its rebuild value per year (20 man-years of rebuild value need about 3 man-years of maintenance every year). Your changes are remembered in this browser for every report.