Mirror Cursor seed with rsync instead of rm -rf plus full cp -R on every start

Start at the ${seed_config} branch in config.assistant-cursor.yaml, lines 10–18, and inspect the existing post-start hook and its host-authoritative comment. Verify rsync availability with command -v rsync, preserve the listed exclusions and fallback behavior, then run the documented DDEV restart benchmark twice; done means unchanged restarts avoid the full copy and the hook still produces the writable configuration.

Problem

The post-start hook in config.assistant-cursor.yaml runs sudo rm -rf "${HOME}/.cursor" followed by a full cp -R -P of the read-only seed mount on every single ddev start. On a real project this took 63,930 ms, the second-slowest hook in a 10m37s start and 10 percent of total start time.

The cost comes from copying data cursor-agent never reads. The seed directory is 713 MB across 37,849 files and 11,299 directories, and it breaks down like this:

• 609 MB extensions/, Cursor IDE extensions, which the CLI agent in a container has no use for
• 67 MB acp-sessions/
• 21 MB projects/
• 7.7 MB chats/
• 4.9 MB ai-tracking/
• several statsig-cache.json.*.tmp files at roughly 700 KB each, left over from host-side writes

That leaves well under 1 percent of the payload as configuration the agent actually needs. The rm -rf also guarantees a full re-copy even when nothing on the host changed, so the cost is paid identically on every restart.

docker-compose.assistant-cursor.yaml mounts the same host directory read-only at ~/.cred-seed/cursor, so the container already has a live view of the host tree. The copy exists only to produce a writable version.

Expected Behavior

Mirroring the host Cursor configuration should be incremental and should skip data the CLI agent does not read. A no-change restart should complete in roughly a second rather than a minute.

rsync ships in the ddev-webserver image (verified at /usr/bin/rsync on ddev-webserver v1.25.4), so rsync -a --delete with an exclude list gives the same "host is authoritative, no merge" semantics the current comment describes, without the wipe-and-recopy:

rsync -a --delete \
  --exclude 'extensions/' \
  --exclude 'chats/' \
  --exclude 'acp-sessions/' \
  --exclude 'ai-tracking/' \
  --exclude 'projects/' \
  --exclude 'statsig-cache.json.*.tmp' \
  "${seed_config}/" "${HOME}/.cursor/"

If rsync cannot be assumed on every supported webserver image, fall back to the current cp -R path when command -v rsync fails.

Steps to Reproduce

1. Install the add-on on a project where the host ~/.cursor has Cursor IDE extensions installed, so the tree is in the hundreds of megabytes.
2. Run export DDEV_VERBOSE=true and then ddev restart.
3. Find the PERF: exit app.Exec line for the assistant-cursor post-start hook and read the elapsed milliseconds.
4. Run ddev restart again without touching the host ~/.cursor. The elapsed time is unchanged, because the hook wipes the target before copying.

Additional Context

Add-on version v1.0.0. Host is Linux, DDEV v1.25.4, ddev-webserver v1.25.4, project uses apache-fpm and PHP 8.3.

The credentials copy at ~/.cred-seed/cursor-auth is only 12 KB and is not worth changing. The problem is entirely in the ${seed_config} branch at config.assistant-cursor.yaml lines 10 to 18.

The same wipe-and-recopy shape appears in the sibling add-ons (assistant-claude, assistant-codex, assistant-copilot), but their seed trees are small enough that the cost is not yet visible. Worth considering a shared approach if this one changes.