[Bug]: Backend crash-loops on startup when a thread in a project with a local-path git remote has a linked PR

[jrevast]

Version or commit

0.0.43-nightly.20260923.2173 (desktop, Linux)

Steps to reproduce

1. Create a repo whose origin is a plain local path: git remote add origin /tmp/r/remote.git.
2. Add it as a project in T3 Code.
3. Link any GitHub PR to a thread in that project.
4. Restart the backend.

Logs or stack traces

ERROR (#4): TypeError: Cannot read properties of undefined (reading 'toLowerCase')
    at .../apps/server/dist/bin.mjs:63528:43
    at Array.filter (<anonymous>)
    at legacyLinkedPullRequestOf (.../bin.mjs:63515:57)
    at mapThreadPullRequests (.../bin.mjs:82090:28)
    at .../bin.mjs:83762:8

Cause

A local-path remote gives the repository identity no provider, so pullRequestHostOf returns undefined as the host.
legacyLinkedPullRequestOf then calls host.toLowerCase() and throws while the backend loads threads at startup, so it exits and restarts about every 30 s.

Workaround

Rewrite the remote as a URL (git remote set-url origin file:///path/to/remote.git), or remove the thread's row from projection_thread_pull_requests.

[juliusmarminge]

Confirmed on current main (d4cd7d5c33). Nightly 0.0.43-nightly.20260923.2173 (68fb7f4b8509) is an ancestor of that commit, and the files below have not changed since, so a newer nightly or the 0.0.43-preview.20260923.2177 build does not contain a fix. No open issue covers this crash. PR #13129 is adjacent: it would stop assigning a repository identity to local-path remotes, which would skip this path, but it is not merged and it does not guard the throw.

What crashes

legacyLinkedPullRequestOf assumes pullRequestHostOf always returns a string:

https://github.com/pingdotgg/t3code/blob/main/packages/shared/src/threadPullRequests.ts#L159-L189

For origin = /tmp/r/remote.git it does not.

• normalizeGitRemoteUrl leaves that remote as /tmp/r/remote. The first / segment is empty.
• detectSourceControlProviderFromGitRemoteUrl returns null for a filesystem path, so the identity is stored with no provider (RepositoryIdentityResolver.buildRepositoryIdentity).
• pullRequestHostOf then falls through to that missing provider and returns undefined:

https://github.com/pingdotgg/t3code/blob/main/packages/contracts/src/pullRequest.ts#L1294-L1315

• The repository selector is still tmp/r/remote (the path below the empty segment), so the function does not return early.
• A GitHub /pull/N link has no authority, so the filter takes the last branch and calls host.toLowerCase(). That is the TypeError in the stack (Array.filter → legacyLinkedPullRequestOf → mapThreadPullRequests).

pullRequestSyncKey already treats an undefined host as “no key” and returns null. This legacy helper does not.

The throw is specific to a canonical key whose first segment is empty. That is a Unix absolute path (/tmp/r/remote.git). These do not throw: file:///… (host becomes "file:"), ., ../other.git, and C:/…. A thread with no linked pull-request row does not throw either, because the filter callback never runs.

Why the process restarts

Startup phase projects.auto-pull loads the shell snapshot, and that maps every non-deleted thread through mapThreadPullRequests:

https://github.com/pingdotgg/t3code/blob/main/apps/server/src/serverRuntimeStartup.ts#L919-L928

https://github.com/pingdotgg/t3code/blob/main/apps/server/src/orchestration/Layers/ProjectionSnapshotQuery.ts#L2716-L2732

The TypeError is an Effect defect. The Effect.catch around that load only handles typed failures, so the defect fails startup. abort dies the activation deferred and the process exits:

https://github.com/pingdotgg/t3code/blob/main/apps/server/src/server.ts#L776-L778

The desktop supervisor then restarts an unexpected exit. The delay starts at 500ms and doubles until it caps at 10s (DesktopBackendManager). A loop that looks like ~30s is startup time plus that cap. There is no 30s timer. Archiving the thread does not help: the shell snapshot still includes archived threads (deletedAt === null only). t3 serve in a terminal exits once and stays down. The same snapshot read also dies on a full snapshot or a thread-detail read, so any client of that server hits it.

Workarounds

Both workarounds in the report stop the crash:

• git remote set-url origin file:///path/to/remote.git gives the host the string "file:", the comparison fails, and the legacy linkedPullRequest field is omitted. The pullRequests rows stay.
• Deleting that thread’s rows in projection_thread_pull_requests leaves the filter with nothing to call.

Fix

If pullRequestHostOf does not return a string, return null from legacyLinkedPullRequestOf before the filter, the same way a missing identity already returns null. Add a regression for an identity with canonical key /tmp/r/remote, no provider, and one GitHub link: the helper returns null and does not throw.