diff --git a/src/app/command_driver.rs b/src/app/command_driver.rs
index af720ea76..bdfe81e3f 100644
--- a/src/app/command_driver.rs
+++ b/src/app/command_driver.rs
@@ -102,6 +102,10 @@ impl OpenCADStudio {
         self.tabs[i].scene.clear_preview_wire();
         self.tabs[i].snap_result = None;
         self.last_point = None;
+        // Points collected in the space being left are meaningless in the new
+        // one (PR1).
+        self.clear_accepted_snaps();
+        self.pending_click_snap = None;
         self.snapper.from_point = None;
         self.snapper.clear_tracking();
         self.otrack_active = None;
@@ -368,6 +372,11 @@ impl OpenCADStudio {
             if !self.command_point_allowed(i, *point) {
                 return Task::none();
             }
+            // Typed / dynamic-input / headless points carry no snap, but the
+            // accepted-snap list must stay index-parallel with the points the
+            // command collects (PR1). Interactive picks record themselves in
+            // the click handler and never reach here.
+            self.record_accepted_snap(None, None, *point);
         }
         if default_start {
             let StepInput::Point(point) = &input else {
@@ -1590,9 +1599,7 @@ impl OpenCADStudio {
                 };
                 if is_associative_dimension && association_enabled {
                     if let Some(handle) = committed {
-                        let sources = self.tabs[i]
-                            .scene
-                            .infer_dimension_sources(handle);
+                        let sources = self.infer_dimension_sources_guarded(i, handle);
                         self.tabs[i]
                             .scene
                             .attach_dimension_association(handle, sources);
@@ -2063,9 +2070,7 @@ impl OpenCADStudio {
                 let committed = self.commit_entity_handle(entity);
                 if is_associative_dimension && association_enabled {
                     if let Some(handle) = committed {
-                        let sources = self.tabs[i]
-                            .scene
-                            .infer_dimension_sources(handle);
+                        let sources = self.infer_dimension_sources_guarded(i, handle);
                         self.tabs[i]
                             .scene
                             .attach_dimension_association(handle, sources);
@@ -2175,9 +2180,7 @@ impl OpenCADStudio {
                                 crate::command::DimensionAssociationInput::Infer(source) => {
                                     let sources: Vec<_> = source.map_or_else(
                                         || {
-                                            self.tabs[i]
-                                                .scene
-                                                .infer_dimension_sources(handle)
+                                            self.infer_dimension_sources_guarded(i, handle)
                                         },
                                         |source| {
                                             if single_source_dimension {
@@ -2302,9 +2305,7 @@ impl OpenCADStudio {
                             crate::command::DimensionAssociationInput::Infer(source) => {
                                 source.map_or_else(
                                     || {
-                                        self.tabs[i]
-                                            .scene
-                                            .infer_dimension_sources(handle)
+                                        self.infer_dimension_sources_guarded(i, handle)
                                             .into_iter()
                                             .map(|source| {
                                                 source.map(
diff --git a/src/app/commands/mod.rs b/src/app/commands/mod.rs
index 3e749827f..a8cf35bc5 100644
--- a/src/app/commands/mod.rs
+++ b/src/app/commands/mod.rs
@@ -120,6 +120,9 @@ impl OpenCADStudio {
         // Reset the last committed point so the first click of the new command
         // is not constrained by ortho/polar relative to a previous command's endpoint.
         self.last_point = None;
+        // A new command collects its own points, so the previous command's
+        // accepted snaps must not leak into it (PR1).
+        self.clear_accepted_snaps();
         // Starting a command restarts the right-click cycle, so its first
         // right-click acts as Enter rather than opening the context menu.
         self.tabs[i]
diff --git a/src/app/mod.rs b/src/app/mod.rs
index 0ad215b09..a4a00956b 100644
--- a/src/app/mod.rs
+++ b/src/app/mod.rs
@@ -707,6 +707,25 @@ pub(super) struct OpenCADStudio {
     show_layout_tabs: bool,
     /// Last point committed by a drawing command — used as ortho/polar base.
     last_point: Option<glam::DVec3>,
+    /// Viewport frame the live snap marker is currently looking through (PR1).
+    /// Set by the cursor-move handler when the displayed snap came from a
+    /// layout viewport, cleared otherwise. Display/bookkeeping only — the point
+    /// itself is already projected onto the sheet.
+    pub(crate) vp_snap_frame: Option<crate::scene::viewport_ref::ViewportFrame>,
+    /// Snaps accepted by the active command's point steps, parallel to the
+    /// points it collected (PR1). A command that does not care keeps using the
+    /// plain paper point; dimension commands (PR2) read the model point,
+    /// viewport and frame from here, and PR3 reads `source`. Cleared whenever a
+    /// command starts or ends.
+    accepted_snaps: Vec<crate::scene::viewport_ref::AcceptedSnap>,
+    /// Snap resolved by the click currently being handled, with the viewport
+    /// frame it came through (PR1). Set inside the click handler's point
+    /// resolution so the point-accept path further down can record the
+    /// [`crate::scene::viewport_ref::AcceptedSnap`] without recomputing.
+    pending_click_snap: Option<(
+        crate::snap::SnapResult,
+        Option<crate::scene::viewport_ref::ViewportFrame>,
+    )>,
     /// Endpoint + unit exit-tangent of the most recently drawn line/arc, so
     /// `ARC_CONT` (Arc → Continue) can start tangentially from where drawing
     /// ended. `None` once a non-line/arc entity is committed.
@@ -3689,6 +3708,9 @@ impl OpenCADStudio {
             show_file_tabs: true,
             show_layout_tabs: true,
             last_point: None,
+            vp_snap_frame: None,
+            accepted_snaps: Vec::new(),
+            pending_click_snap: None,
             main_window: None,
             thumbnail_capture_clean: false,
             #[cfg(not(target_arch = "wasm32"))]