Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@ui/src/features/dags/components/dag-editor/DAGSpec.tsx`:
- Around line 83-84: The SSE subscription call useDAGSSE(fileName, true) in
DAGSpec.tsx must include the remoteNode routing parameter so events are scoped
to the currently selected node; update the call to pass the remoteNode (e.g.,
useDAGSSE(fileName, true, remoteNode)) or the appropriate selected-node variable
available in this component, and ensure any related hook signature (useDAGSSE)
is updated to accept and forward remoteNode to the backend so all SSE requests
include the remoteNode parameter.

In `@ui/src/hooks/useContentEditor.ts`:
- Around line 121-136: The conflict resolution in resolveConflict uses a truthy
check (if (conflict.externalContent)) which skips valid empty-string external
updates; change the checks to explicitly test for null/undefined (e.g.,
conflict.externalContent != null or typeof conflict.externalContent !==
'undefined') so empty '' is handled; update both the 'discard' and 'ignore'
branches to set lastServerContentRef.current, and in the 'discard' branch also
set currentValueRef.current, call setCurrentValueState(conflict.externalContent)
and set hasUserEditedRef.current = false when externalContent is not
null/undefined.

In `@ui/src/pages/docs/components/DocEditor.tsx`:
- Around line 38-53: If SSE (useDocSSE) never provides initial content
(sseResult.data), add a non-SSE fallback fetch to populate the serverContent
passed into useContentEditor: create local state (e.g., initialServerContent),
trigger an effect when sseResult.data is undefined or sseResult.error and fetch
the doc content for docPath via the REST/HTTP endpoint your app uses, set
initialServerContent with the fetched content, then call useContentEditor with
serverContent: doc?.content ?? initialServerContent ?? null so hasUnsavedChanges
can become true and save is enabled even if SSE hasn't delivered data.
- Around line 39-40: The SSE subscription in DocEditor is missing the remoteNode
routing parameter, so update the call to useDocSSE to include the current remote
node context (e.g., pass remoteNode along with docPath) so SSEs are scoped to
the selected node; locate the useDocSSE invocation and modify it to
accept/forward remoteNode (and ensure any downstream sseResult/data handling
still uses the returned value).