fix: Prevent ghost extremities #2346

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nex merged 5 commits from nex/fix/extremities-yet-again into main 2026-10-12 21:31:06 +00:00

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nex commented 2026-10-11 20:49:24 +00:00

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This pull request marks all events received during a join (state events and auth chain events) as referenced, which means we will not add them to the extremity list, and consequently won't start referring to chunks of the room DAG from before when we joined. This already happens when receiving new events (we don't add events sent before our join to the extremity list), and backfilling also automatically marks events as referenced, so this just covers auth events (which are outliers, neither appended nor backfilled).
It also removes any extremities from the list that we don't have locally. This prevents events being added that might not exist, or that we aren't allowed to fetch, etc.

Fixes: #2344

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This pull request marks all events received during a join (state events and auth chain events) as referenced, which means we will not add them to the extremity list, and consequently won't start referring to chunks of the room DAG from before when we joined. This already happens when receiving new events (we don't add events sent before our join to the extremity list), and backfilling also automatically marks events as referenced, so this just covers auth events (which are outliers, neither appended nor backfilled). It also removes any extremities from the list that we don't have locally. This prevents events being added that might not exist, or that we aren't allowed to fetch, etc. Fixes: #2344 <!-- Example: This pull request allows us to warp through time and space ten times faster than before by double-inverting the warp drive with hyperheated jump fluid, both making the drive faster and more efficient. This resolves the common issue where we have to wait more than 10 milliseconds to engage, use, and disengage the warp drive when travelling between galaxies. --> <!-- Closes: #... --> <!-- Fixes: #... --> <!-- Uncomment the above line(s) if your pull request fixes an issue or closes another pull request by superseding it. Replace `#...` with the issue/pr number, such as `#123`. --> **Pull request checklist:** <!-- You need to complete these before your PR can be considered. If you aren't sure about some, feel free to ask for clarification in #dev:continuwuity.org. --> - [x] This pull request targets the `main` branch, and the branch is named something other than `main`. - [x] I have written an appropriate pull request title and my description is clear. - [x] I understand I am responsible for the contents of this pull request. - I have followed the [contributing guidelines][c1]: - [x] My contribution follows the [code style][c2], if applicable. - [x] I ran [pre-commit checks][c1pc] before opening/drafting this pull request. - [x] I have [tested my contribution][c1t] (or proof-read it for documentation-only changes) myself, if applicable. This includes ensuring code compiles. - [x] My commit messages follow the [commit message format][c1cm] and are descriptive. <!-- Notes on these requirements: - While not required, we encourage you to sign your commits with GPG or SSH to attest the authenticity of your changes. - While we allow LLM-assisted contributions, we do not appreciate contributions that are low quality, which is typical of machine-generated contributions that have not had a lot of love and care from a human. Please do not open a PR if all you have done is asked ChatGPT to tidy up the codebase with a +-100,000 diff. - In the case of code style violations, reviewers may leave review comments/change requests indicating what the ideal change would look like. For example, a reviewer may suggest you lower a log level, or use `match` instead of `if/else` etc. - In the case of code style violations, pre-commit check failures, minor things like typos/spelling errors, and in some cases commit format violations, reviewers may modify your branch directly, typically by making changes and adding a commit. Particularly in the latter case, a reviewer may rebase your commits to squash "spammy" ones (like "fix", "fix", "actually fix"), and reword commit messages that don't satisfy the format. - Pull requests MUST pass the `Checks` CI workflows to be capable of being merged. This can only be bypassed in exceptional circumstances. If your CI flakes, let us know in matrix:r/dev:continuwuity.org. - Pull requests have to be based on the latest `main` commit before being merged. If the main branch changes while you're making your changes, you should make sure you rebase on main before opening a PR. Your branch will be rebased on main before it is merged if it has fallen behind. - We typically only do fast-forward merges, so your entire commit log will be included. Once in main, it's difficult to get out cleanly, so put on your best dress, smile for the cameras! --> [c1]: https://forgejo.ellis.link/continuwuation/continuwuity/src/branch/main/CONTRIBUTING.md [c2]: https://forgejo.ellis.link/continuwuation/continuwuity/src/branch/main/docs/development/code_style.mdx [c1pc]: https://forgejo.ellis.link/continuwuation/continuwuity/src/branch/main/CONTRIBUTING.md#pre-commit-checks [c1t]: https://forgejo.ellis.link/continuwuation/continuwuity/src/branch/main/CONTRIBUTING.md#running-tests-locally [c1cm]: https://forgejo.ellis.link/continuwuation/continuwuity/src/branch/main/CONTRIBUTING.md#commit-messages

nex added the

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nex self-assigned this 2026-10-11 20:49:24 +00:00

nex added 2 commits 2026-10-11 20:49:24 +00:00

fix: Never add unknown events to the extremity tracker 64dc46fa29

fix: Mark PDUs as referenced during gapfill immediately 2a11737add

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label 2026-10-11 20:49:30 +00:00

nex added 1 commit 2026-10-11 20:52:36 +00:00

fix: Mark state and auth chain events as referenced after joining a room ... 19010d5439

It's generally safe to assume that all of these events have been referenced by the time we get to joining.

nex added 1 commit 2026-10-11 21:04:33 +00:00

fix: Don't unconditionally mark gapfilled events as referenced ... a0c6fd0ed3

This is pointless and fallible

nex 2026-10-11 21:08:39 +00:00

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nex added 1 commit 2026-10-11 21:12:41 +00:00

style: Remove import 871c406c36

Aranjedeath approved these changes 2026-10-12 21:26:06 +00:00

nex force-pushed nex/fix/extremities-yet-again from 871c406c36 to 090203c2ea 2026-10-12 21:30:46 +00:00 Compare

nex merged commit 090203c2ea into main 2026-10-12 21:31:06 +00:00

nex deleted branch nex/fix/extremities-yet-again 2026-10-12 21:31:06 +00:00

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