matrix-avatar-sync ran on every boot (RemainAfterExit=false + path
trigger), uploading a fresh PNG each time. Every upload mints a new
mxc:// URI, which triggers a profile state event in every joined room
— resulting in timeline spam even when the avatar hasn't changed.
Fix: before uploading, compute sha256sum of /etc/hyperhive/icon.svg
and compare against the last-synced hash stored in
$HYPERHIVE_STATE_DIR/matrix-avatar-icon-hash. Skip the upload if the
hash matches. Write the hash after a successful avatar_url PUT so
subsequent boots are no-ops until the icon file changes.
Hash file lives in the agent's state dir — survives restart, cleared
on purge (so purge + re-provision gets a fresh upload). Delete to force
re-upload manually.
Closes#1231
644519f358