diff --git a/toki-api/src/routes/time_tracking/timer.rs b/toki-api/src/routes/time_tracking/timer.rs
index 1ffa35dc..7389498e 100644
--- a/toki-api/src/routes/time_tracking/timer.rs
+++ b/toki-api/src/routes/time_tracking/timer.rs
@@ -14,6 +14,46 @@ use tracing::instrument;
 
 use super::CookieJarResult;
 
+const SAVE_TIMER_PARTIAL_UPDATE_ERROR: &str = "Project/activity update must be atomic: provide projectId, projectName, activityId, and activityName together.";
+
+#[derive(Debug, PartialEq, Eq)]
+struct AtomicSaveTimerProjectActivityUpdate {
+    project_id: String,
+    project_name: String,
+    activity_id: String,
+    activity_name: String,
+}
+
+fn parse_save_timer_project_activity_update(
+    body: &SaveTimerPayload,
+) -> Result<Option<AtomicSaveTimerProjectActivityUpdate>, ApiError> {
+    let has_any_update = body.project_id.is_some()
+        || body.project_name.is_some()
+        || body.activity_id.is_some()
+        || body.activity_name.is_some();
+
+    if !has_any_update {
+        return Ok(None);
+    }
+
+    match (
+        body.project_id.clone(),
+        body.project_name.clone(),
+        body.activity_id.clone(),
+        body.activity_name.clone(),
+    ) {
+        (Some(project_id), Some(project_name), Some(activity_id), Some(activity_name)) => {
+            Ok(Some(AtomicSaveTimerProjectActivityUpdate {
+                project_id,
+                project_name,
+                activity_id,
+                activity_name,
+            }))
+        }
+        _ => Err(ApiError::bad_request(SAVE_TIMER_PARTIAL_UPDATE_ERROR)),
+    }
+}
+
 // ============================================================================
 // Get Timer
 // ============================================================================
@@ -109,6 +149,10 @@ pub async fn stop_timer(
 #[serde(rename_all = "camelCase")]
 pub struct SaveTimerPayload {
     user_note: Option<String>,
+    project_id: Option<String>,
+    project_name: Option<String>,
+    activity_id: Option<String>,
+    activity_name: Option<String>,
 }
 
 #[instrument(name = "save_timer", skip(jar))]
@@ -123,7 +167,31 @@ pub async fn save_timer(
         .create_service(jar, &app_state.cookie_domain)
         .await?;
 
-    service.save_timer(&user.id, body.user_note).await?;
+    let parsed_update = parse_save_timer_project_activity_update(&body)?;
+    let user_note = body.user_note;
+
+    // Allow clients to include latest project/activity values in the save call.
+    // This makes save robust if a prior timer-edit sync call was missed.
+    if let Some(AtomicSaveTimerProjectActivityUpdate {
+        project_id,
+        project_name,
+        activity_id,
+        activity_name,
+    }) = parsed_update
+    {
+        let current_timer = service
+            .get_active_timer(&user.id)
+            .await?
+            .ok_or_else(|| ApiError::not_found("no active timer found"))?;
+
+        let updated_timer = ActiveTimer::new(current_timer.started_at)
+            .with_project(project_id, project_name)
+            .with_activity(activity_id, activity_name)
+            .with_note(current_timer.note);
+        service.edit_timer(&user.id, &updated_timer).await?;
+    }
+
+    service.save_timer(&user.id, user_note).await?;
 
     Ok((jar, StatusCode::OK))
 }
@@ -227,3 +295,102 @@ pub async fn get_timer_history(
 
     Ok((jar, Json(response)))
 }
+
+#[cfg(test)]
+mod tests {
+    use axum::response::IntoResponse;
+
+    use super::*;
+
+    fn save_payload(
+        project_id: Option<&str>,
+        project_name: Option<&str>,
+        activity_id: Option<&str>,
+        activity_name: Option<&str>,
+    ) -> SaveTimerPayload {
+        SaveTimerPayload {
+            user_note: None,
+            project_id: project_id.map(ToString::to_string),
+            project_name: project_name.map(ToString::to_string),
+            activity_id: activity_id.map(ToString::to_string),
+            activity_name: activity_name.map(ToString::to_string),
+        }
+    }
+
+    #[test]
+    fn parse_save_timer_update_accepts_no_project_or_activity_fields() {
+        let body = save_payload(None, None, None, None);
+        let parsed = if let Ok(parsed) = parse_save_timer_project_activity_update(&body) {
+            parsed
+        } else {
+            panic!("expected parse success");
+        };
+        assert_eq!(parsed, None);
+    }
+
+    #[test]
+    fn parse_save_timer_update_accepts_atomic_project_and_activity_fields() {
+        let body = save_payload(Some("p1"), Some("Project"), Some("a1"), Some("Activity"));
+        let parsed = if let Ok(parsed) = parse_save_timer_project_activity_update(&body) {
+            parsed
+        } else {
+            panic!("expected parse success");
+        };
+        assert_eq!(
+            parsed,
+            Some(AtomicSaveTimerProjectActivityUpdate {
+                project_id: "p1".to_string(),
+                project_name: "Project".to_string(),
+                activity_id: "a1".to_string(),
+                activity_name: "Activity".to_string()
+            })
+        );
+    }
+
+    fn assert_bad_request_for_partial_update(body: SaveTimerPayload) {
+        let err =
+            parse_save_timer_project_activity_update(&body).expect_err("expected bad request");
+        let response = err.into_response();
+        assert_eq!(response.status(), StatusCode::BAD_REQUEST);
+    }
+
+    #[test]
+    fn parse_save_timer_update_rejects_project_only_pair() {
+        let body = save_payload(Some("p1"), Some("Project"), None, None);
+        assert_bad_request_for_partial_update(body);
+    }
+
+    #[test]
+    fn parse_save_timer_update_rejects_activity_only_pair() {
+        let body = save_payload(None, None, Some("a1"), Some("Activity"));
+        assert_bad_request_for_partial_update(body);
+    }
+
+    #[test]
+    fn parse_save_timer_update_rejects_single_field_partials() {
+        let cases = [
+            save_payload(Some("p1"), None, None, None),
+            save_payload(None, Some("Project"), None, None),
+            save_payload(None, None, Some("a1"), None),
+            save_payload(None, None, None, Some("Activity")),
+        ];
+
+        for body in cases {
+            assert_bad_request_for_partial_update(body);
+        }
+    }
+
+    #[test]
+    fn parse_save_timer_update_rejects_mixed_partial_pairs() {
+        let cases = [
+            save_payload(Some("p1"), Some("Project"), Some("a1"), None),
+            save_payload(Some("p1"), Some("Project"), None, Some("Activity")),
+            save_payload(Some("p1"), None, Some("a1"), Some("Activity")),
+            save_payload(None, Some("Project"), Some("a1"), Some("Activity")),
+        ];
+
+        for body in cases {
+            assert_bad_request_for_partial_update(body);
+        }
+    }
+}
diff --git a/toki-tui/src/api/client.rs b/toki-tui/src/api/client.rs
index 625b6783..8418b27c 100644
--- a/toki-tui/src/api/client.rs
+++ b/toki-tui/src/api/client.rs
@@ -9,8 +9,9 @@ use std::sync::Arc;
 use crate::api::dev_backend::DevBackend;
 use crate::api::dto::{
     ActivityDto, AuthenticateRequest, DeleteEntryRequest, EditEntryRequest, ProjectDto,
-    SaveTimerRequest, StartTimerRequest, UpdateActiveTimerRequest,
+    StartTimerRequest, UpdateActiveTimerRequest,
 };
+use crate::api::SaveTimerRequest;
 use crate::session_store;
 use crate::types::{
     ActiveTimerState, Activity, GetTimerResponse, Me, Project, TimeEntry, TimeInfo,
@@ -288,7 +289,7 @@ impl ApiClient {
         .await
     }
 
-    pub async fn save_timer(&mut self, note: Option<String>) -> Result<()> {
+    pub async fn save_timer(&mut self, request: SaveTimerRequest) -> Result<()> {
         if self.dev_backend.is_some() {
             return Ok(());
         }
@@ -296,7 +297,7 @@ impl ApiClient {
         self.send_without_body(
             self.client
                 .put(self.endpoint("/time-tracking/timer")?)
-                .json(&SaveTimerRequest { user_note: note }),
+                .json(&request),
             "PUT /time-tracking/timer",
             UNAUTH_RELOGIN,
         )
diff --git a/toki-tui/src/api/dto.rs b/toki-tui/src/api/dto.rs
index a69778f3..00f50a24 100644
--- a/toki-tui/src/api/dto.rs
+++ b/toki-tui/src/api/dto.rs
@@ -28,6 +28,10 @@ pub struct StartTimerRequest {
 #[serde(rename_all = "camelCase")]
 pub struct SaveTimerRequest {
     pub user_note: Option<String>,
+    pub project_id: Option<String>,
+    pub project_name: Option<String>,
+    pub activity_id: Option<String>,
+    pub activity_name: Option<String>,
 }
 
 #[derive(Serialize)]
diff --git a/toki-tui/src/api/mod.rs b/toki-tui/src/api/mod.rs
index 9f3aac43..70f89802 100644
--- a/toki-tui/src/api/mod.rs
+++ b/toki-tui/src/api/mod.rs
@@ -3,3 +3,4 @@ mod dev_backend;
 mod dto;
 
 pub use client::ApiClient;
+pub(crate) use dto::SaveTimerRequest;
diff --git a/toki-tui/src/runtime/actions.rs b/toki-tui/src/runtime/actions.rs
index daf54be0..298e82a7 100644
--- a/toki-tui/src/runtime/actions.rs
+++ b/toki-tui/src/runtime/actions.rs
@@ -1,4 +1,4 @@
-use crate::api::ApiClient;
+use crate::api::{ApiClient, SaveTimerRequest};
 use crate::app::{self, App, TextInput};
 use crate::types;
 use anyhow::{Context, Result};
@@ -317,9 +317,16 @@ pub(super) async fn handle_save_timer_with_action(
 
     let project_display = app.current_project_name();
     let activity_display = app.current_activity_name();
+    let save_request = SaveTimerRequest {
+        user_note: note,
+        project_id: app.selected_project.as_ref().map(|p| p.id.clone()),
+        project_name: app.selected_project.as_ref().map(|p| p.name.clone()),
+        activity_id: app.selected_activity.as_ref().map(|a| a.id.clone()),
+        activity_name: app.selected_activity.as_ref().map(|a| a.name.clone()),
+    };
 
     // Save the active timer to Milltime
-    match client.save_timer(note.clone()).await {
+    match client.save_timer(save_request).await {
         Ok(()) => {
             let hours = duration.as_secs() / 3600;
             let minutes = (duration.as_secs() % 3600) / 60;