docs: document save slots and auto-sync being on by default

[gantoine]

What

The saves documentation described emulatorjs.auto_save_sync as an opt-in that uploads on save-and-quit unless you turn it on. Since 5.3.0 it defaults to true (config_manager.py) and the player polls the emulator's save memory every second, so a save reaches the server seconds after the game writes it. Following that thread, two more things shipped with no docs at all.

• docs/using/saves-and-states.md
  • Automatic save sync rewritten: on by default, how it actually works, the opt-out, and what happens to an upload the server doesn't take (held in the browser with its screenshot, retried later, scoped to the account that made it).
  • New Save slots section: autosave vs named slots, version history and the Latest tag, and MAX_SAVES_PER_SLOT retention.
  • In-emulator behaviour updated: EmulatorJS' Export/Import save buttons are hidden now, replaced by Load save or state (and Sync save when auto-sync is off).
  • Reworded the "save disappears after play" troubleshooting entry, which assumed the old flush-on-quit behaviour.
• docs/reference/configuration-file.md: emulatorjs.auto_save_sync default corrected to true, with the sample showing the opt-out.
• scripts/sources.toml: pinned romm ref bumped from 839605e to 5.3.0-beta.1 so the generated env-var table picks up MAX_SAVES_PER_SLOT.

Source

Behaviour verified against 5.3.0-beta.1 rather than PR descriptions:

Claim	Source
Default is true	backend/config/config_manager.py:762
Polls save memory every second	frontend/src/views/Player/EmulatorJS/utils.ts:378 (SAVE_SYNC_POLL_MS)
Leaving the player flushes a pending save	Player.vue, flushPendingSave on onBeforeRouteLeave
Failed uploads held and retried, per account	frontend/src/services/pending-asset.ts
Retention is the tighter of server cap and client ask; slot-less saves never pruned	backend/endpoints/saves.py:128-133, :369-371
Sync save button only when auto-sync is off	Player.vue:344-351

Relevant PRs: rommapp/romm#4378, rommapp/romm#4517, rommapp/romm#4540, rommapp/romm#4558, rommapp/romm#4600, rommapp/romm#4615

Generated snippets

Re-ran all four generators after the ref bump. Only env-vars.md changed, and only by two rows: MAX_SAVES_PER_SLOT added, and WEB_SERVER_KEEPALIVE picking up its new 65 default. platform-aliases.md, scheduled-tasks.md and supported-platforms.md came back byte-identical.

Testing

uv run mkdocs build is clean, no link or anchor warnings. --strict aborts locally on an unrelated missing libcairo for social-card rendering, which is an environment issue rather than anything in this change. trunk check passes on the edited files.

AI assistance

Written with Claude Code. The prose is model-written; every behavioural claim was checked against the code in the table above by the model, and the whole diff was reviewed by me before opening.

🤖 Generated with Claude Code