Lists are grabbed automatically, on AutoGet's rules (#926)

[chchatzop]

Item 5 of #926, which is the last item. Stacked on #933 because they touch the same changelog heads. Retarget it to main once the stack below it merges.

New list_grab.py. When AUTO_GRAB_LISTS is on (it is off by default), DCCore asks for the list of any bot that advertises one and whose list we don't hold yet. It follows AutoGet's rules:

• One at a time: at most one grab every AUTO_GRAB_EVERY_MINUTES (10), biggest list first.
• Random wait: 5 to 360 seconds before asking, so clients that saw the same advert don't all ask at once.
• Someone else asked: if another user types @Bot in a channel, a grab waiting on that bot is dropped and the bot is left alone for 10 minutes, because it's busy sending that user's list. This doesn't count as a try.
• 3 tries, 30 minutes apart, then it stops. AutoGet's own counter shows only 37% of list requests ever arrived.
• Skipped bots: bots that are offline, our own nick, bots below AUTO_GRAB_MIN_FILES, bots advertising less than AUTO_GRAB_MIN_SPEED_KB (a bot that shows no speed isn't skipped), bots in "servers only" mode, and bots whose list the operator removed by hand. purge_fetched_list() records that. The bulk purge of offline bots doesn't, because that is tidying up, not a decision about the bot.
• Checked again after the wait: a bot that left in the meantime isn't asked.

Each ask goes through build_list_fetch_enqueue_result(), the same path as the List Browser button, so all the slot limits and duplicate guards still apply. Each grab also writes a console line.

State: the current wait, the time of the last grab and the start guard live in runtime.py, so a rehash doesn't forget a wait or start a second worker. The per-bot tries and the removed-by-hand list are saved in data/list_grabs.json, so a restart doesn't reset the three tries. list_grab_others_asked is bound in defaults.py and listed in PRESERVE_RUNTIME. The worker starts from boot and from rehash, the same way the list refresh does.

Settings: the four settings have their own Grabbing lists category, placed just above Fetching from bots. It sits there so it doesn't collide with #928's Fetch queue, which is added just below that category. They have help text and en/es/fr labels, and settings.conf.sample is regenerated.

Tests: tests/test_lists_are_grabbed_automatically_on_autogets_rules.py has 26 tests. I mutation-checked them: 13 mutations, one per rule, and each one fails a test. The full suite passes on this branch, and also with #925, #929 and #930 merged in.

🤖 Generated with Claude Code

https://claude.ai/code/session_01AP6LSxkr4n9dMFNSNMogmW