diff --git a/codebase2/codebase-sqlite/U/Codebase/Sqlite/Queries.hs b/codebase2/codebase-sqlite/U/Codebase/Sqlite/Queries.hs
index 033efb8655..5ae0267130 100644
--- a/codebase2/codebase-sqlite/U/Codebase/Sqlite/Queries.hs
+++ b/codebase2/codebase-sqlite/U/Codebase/Sqlite/Queries.hs
@@ -145,6 +145,7 @@ module U.Codebase.Sqlite.Queries
     -- ** remote project branches
     loadRemoteBranch,
     ensureRemoteProjectBranch,
+    setRemoteProjectBranchLastKnownCausalHash,
     expectRemoteProjectBranchName,
     setRemoteProjectBranchName,
     insertBranchRemoteMapping,
@@ -256,6 +257,7 @@ module U.Codebase.Sqlite.Queries
     addCurrentProjectPathTable,
     addProjectBranchReflogTable,
     addProjectBranchCausalHashIdColumn,
+    trackLatestRemoteHead,
 
     -- ** schema version
     currentSchemaVersion,
@@ -486,6 +488,10 @@ addProjectBranchCausalHashIdColumn :: Transaction ()
 addProjectBranchCausalHashIdColumn =
   executeStatements $(embedProjectStringFile "sql/014-add-project-branch-causal-hash-id.sql")
 
+trackLatestRemoteHead :: Transaction ()
+trackLatestRemoteHead =
+  executeStatements $(embedProjectStringFile "sql/018-track-latest-remote-head.sql")
+
 schemaVersion :: Transaction SchemaVersion
 schemaVersion =
   queryOneCol
@@ -4149,7 +4155,8 @@ loadRemoteBranch rpid host rbid =
         project_id,
         branch_id,
         host,
-        name
+        name,
+        last_known_causal_hash
       FROM
         remote_project_branch
       WHERE
@@ -4158,28 +4165,46 @@ loadRemoteBranch rpid host rbid =
         AND host = :host
     |]
 
-ensureRemoteProjectBranch :: RemoteProjectId -> URI -> RemoteProjectBranchId -> ProjectBranchName -> Transaction ()
-ensureRemoteProjectBranch rpid host rbid name =
+ensureRemoteProjectBranch :: RemoteProjectId -> URI -> RemoteProjectBranchId -> ProjectBranchName -> Maybe CausalHashId -> Transaction ()
+ensureRemoteProjectBranch rpid host rbid name lastKnownCausalHash =
   execute
     [sql|
       INSERT INTO remote_project_branch (
         project_id,
         host,
         branch_id,
-        name)
+        name,
+        last_known_head)
       VALUES (
         :rpid,
         :host,
         :rbid,
-        :name)
+        :name,
+        :lastKnownCausalHash
+        )
       ON CONFLICT (
         project_id,
         branch_id,
         host)
-        -- should this update the name instead?
-        DO NOTHING
+        DO UPDATE
+          SET name = :name,
+              last_known_causal_hash = :lastKnownCausalHash
         |]
 
+setRemoteProjectBranchLastKnownCausalHash :: URI -> RemoteProjectId -> RemoteProjectBranchId -> CausalHashId -> Transaction ()
+setRemoteProjectBranchLastKnownCausalHash host rpid rbid causalHashId =
+  execute
+    [sql|
+      UPDATE
+        remote_project_branch
+      SET
+        last_known_causal_hash = :causalHashId
+      WHERE
+        project_id = :rpid
+        AND branch_id = :rbid
+        AND host = :host
+    |]
+
 expectRemoteProjectBranchName :: URI -> RemoteProjectId -> RemoteProjectBranchId -> Transaction ProjectBranchName
 expectRemoteProjectBranchName host projectId branchId =
   queryOneCol
diff --git a/codebase2/codebase-sqlite/U/Codebase/Sqlite/RemoteProjectBranch.hs b/codebase2/codebase-sqlite/U/Codebase/Sqlite/RemoteProjectBranch.hs
index 5e5638c274..6dff479efc 100644
--- a/codebase2/codebase-sqlite/U/Codebase/Sqlite/RemoteProjectBranch.hs
+++ b/codebase2/codebase-sqlite/U/Codebase/Sqlite/RemoteProjectBranch.hs
@@ -5,7 +5,7 @@ where
 
 import Network.URI (URI)
 import Network.URI.Orphans.Sqlite ()
-import U.Codebase.Sqlite.DbId (RemoteProjectBranchId, RemoteProjectId)
+import U.Codebase.Sqlite.DbId (CausalHashId, RemoteProjectBranchId, RemoteProjectId)
 import Unison.Core.Orphans.Sqlite ()
 import Unison.Core.Project (ProjectBranchName)
 import Unison.Prelude
@@ -15,7 +15,9 @@ data RemoteProjectBranch = RemoteProjectBranch
   { projectId :: RemoteProjectId,
     branchId :: RemoteProjectBranchId,
     host :: URI,
-    name :: ProjectBranchName
+    name :: ProjectBranchName,
+    -- Note that there's no guarantee that the causals for this hash have been downloaded/synced into the codebase.
+    lastKnownCausalHash :: CausalHashId
   }
   deriving stock (Generic, Show)
   deriving anyclass (ToRow, FromRow)
diff --git a/codebase2/codebase-sqlite/sql/018-track-latest-remote-head.sql b/codebase2/codebase-sqlite/sql/018-track-latest-remote-head.sql
new file mode 100644
index 0000000000..cb92fb4eb3
--- /dev/null
+++ b/codebase2/codebase-sqlite/sql/018-track-latest-remote-head.sql
@@ -0,0 +1,7 @@
+-- Add a field for tracking the latest known causal hash for each remote project branch.
+-- It's helpful for when we need to tell Share how much we know about a branch.
+
+ALTER TABLE remote_project
+  -- Note that there isn't a guarantee this hash has actually been synced into the codebase.
+  ADD COLUMN last_known_causal_hash INTEGER NULL REFERENCES hash(id)
+    ON DELETE SET NULL;
diff --git a/codebase2/codebase-sqlite/unison-codebase-sqlite.cabal b/codebase2/codebase-sqlite/unison-codebase-sqlite.cabal
index 2641df87cd..b6c881c7c9 100644
--- a/codebase2/codebase-sqlite/unison-codebase-sqlite.cabal
+++ b/codebase2/codebase-sqlite/unison-codebase-sqlite.cabal
@@ -1,6 +1,6 @@
 cabal-version: 1.12
 
--- This file has been generated from package.yaml by hpack version 0.36.0.
+-- This file has been generated from package.yaml by hpack version 0.37.0.
 --
 -- see: https://github.com/sol/hpack
 
@@ -24,6 +24,7 @@ extra-source-files:
     sql/012-add-current-project-path-table.sql
     sql/013-add-project-branch-reflog-table.sql
     sql/014-add-project-branch-causal-hash-id.sql
+    sql/018-track-latest-remote-head.sql
     sql/create.sql
 
 source-repository head
diff --git a/parser-typechecker/src/Unison/Codebase/SqliteCodebase/Migrations.hs b/parser-typechecker/src/Unison/Codebase/SqliteCodebase/Migrations.hs
index 9052e5511a..61ff07d9ff 100644
--- a/parser-typechecker/src/Unison/Codebase/SqliteCodebase/Migrations.hs
+++ b/parser-typechecker/src/Unison/Codebase/SqliteCodebase/Migrations.hs
@@ -84,7 +84,8 @@ migrations regionVar getDeclType termBuffer declBuffer rootCodebasePath =
       sqlMigration 14 Q.addSquashResultTable,
       sqlMigration 15 Q.addSquashResultTableIfNotExists,
       sqlMigration 16 Q.cdToProjectRoot,
-      (17 {- This migration takes a raw sqlite connection -}, \conn -> migrateSchema16To17 conn)
+      (17 {- This migration takes a raw sqlite connection -}, \conn -> migrateSchema16To17 conn),
+      sqlMigration 18 Q.trackLatestRemoteHead
     ]
   where
     runT :: Sqlite.Transaction () -> Sqlite.Connection -> IO ()
diff --git a/unison-cli/src/Unison/Cli/Share/Projects.hs b/unison-cli/src/Unison/Cli/Share/Projects.hs
index 52fbc56e8e..056e2790c3 100644
--- a/unison-cli/src/Unison/Cli/Share/Projects.hs
+++ b/unison-cli/src/Unison/Cli/Share/Projects.hs
@@ -49,9 +49,11 @@ import Unison.Codebase.Editor.Output qualified as Output
 import Unison.Hash32 (Hash32)
 import Unison.Prelude
 import Unison.Project (ProjectAndBranch (..), ProjectBranchName, ProjectName)
+import Unison.Share.API.Hash qualified as HashJWT
 import Unison.Share.API.Projects qualified as Share.API
 import Unison.Share.Codeserver (defaultCodeserver)
 import Unison.Share.Types (codeserverBaseURL)
+import Unison.Sync.Common qualified as Sync
 
 -- | Get a project by id.
 --
@@ -193,14 +195,17 @@ onGotProjectBranch :: Share.API.ProjectBranch -> Cli RemoteProjectBranch
 onGotProjectBranch branch = do
   let projectId = RemoteProjectId (branch ^. #projectId)
   let branchId = RemoteProjectBranchId (branch ^. #branchId)
+  let causalHash = Sync.hash32ToCausalHash $ HashJWT.hashJWTHash (branch ^. #branchHead)
   projectName <- validateProjectName (branch ^. #projectName)
   branchName <- validateBranchName (branch ^. #branchName)
   Cli.runTransaction do
+    causalHashId <- Queries.saveCausalHash causalHash
     Queries.ensureRemoteProjectBranch
       projectId
       hardCodedUri
       branchId
       branchName
+      (Just causalHashId)
   pure
     RemoteProjectBranch
       { projectId,