How do I access debian 10 safe storage to enable Sync given the i3 tiling window manager?

After logging in to debian 10 with the i3 tiling window manager, the Brave Sync FAQ tells me to open the ‘Passwords and Keys’ app. How do I do so? Which terminal command is it? How do I access it via dmenu? How do I get Sync working again with i3 in Debian 10?

Do you have this app?
https://wiki.debian.org/Seahorse

I think I do not: ‘seahorse&’ yields ‘seahorse: command not found’. ‘man seahorse’ returns ‘No manual entry for seahorse’. ‘info seahorse’ yields ‘No menu item ‘seahorse’ in node ‘(dir)Top’’.

I was using Cinnamon (or ‘LightDM’?) before starting to use i3, if that helps identify what packages I’m using. Checking Debian’s password management list against Synaptic I have found that gnome-keyring and passwd are installed, if that’s helpful. Yet I have never had to use these before, so how has i3 changed things?

I installed seahorse, unlocked the ‘Login’ item under the ‘Passwords’ heading, and found ‘Brave Safe Storage’ is already there. Closing Brave and reopening it, sync still hasn’t resumed. How do we fix it?

Executing brave-browser& in the terminal I discover this output:

[4387:4387:0328/074033.809207:ERROR:brave_sync_prefs.cc(132)] Decrypt sync seed failure
[4422:4422:0328/074033.894205:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.894304:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.894346:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.894385:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.894426:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.894464:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.894501:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.894539:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.894582:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.894625:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.894667:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.894721:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.894771:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.894825:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.894875:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.894919:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.894986:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895048:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895105:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895155:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895196:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895248:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895302:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895346:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895397:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895437:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895484:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895520:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895549:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895579:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895606:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895632:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895665:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895695:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895724:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895753:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895780:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895808:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895836:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
[4422:4422:0328/074033.895866:ERROR:gbm_wrapper.cc(255)] Failed to export buffer to dma_buf: No such file or directory (2)
main@PCtower:~$ [4387:4387:0328/074033.900811:ERROR:brave_sync_prefs.cc(132)] Decrypt sync seed failure
[4387:4387:0328/074034.166476:ERROR:brave_sync_prefs.cc(132)] Decrypt sync seed failure
[4387:4387:0328/074034.166638:ERROR:CONSOLE(2130)] "[Brave Settings Overrides] Appearance Page cannot find use default theme button template", source: chrome://settings/settings.js (2130)
[4387:4387:0328/074034.167315:ERROR:brave_sync_prefs.cc(132)] Decrypt sync seed failure