diff --git a/crates/render/src/cache.rs b/crates/render/src/cache.rs
index b6f2e4076..cf1a84e82 100644
--- a/crates/render/src/cache.rs
+++ b/crates/render/src/cache.rs
@@ -527,7 +527,7 @@ pub fn input_key(ctx: &EvalCtx, layer: &Layer, scale: f64, draft: bool, blur: bo
     if layer.switches.adjustment || history_unkeyable(layer, Some(effects)) {
         return None;
     }
-    let base = key_any(ctx, layer, scale, draft, blur, true, Some(effects))?;
+    let base = key_any(ctx, layer, scale, draft, blur, true, EffectScope::First(effects))?;
     let mut h = KeyHasher(base ^ 0x5bd1_e995_7a3c_11d3);
     effects.hash(&mut h);
     Some(h.finish())
@@ -588,25 +588,39 @@ fn has_expression(g: &PropGroup) -> bool {
     })
 }
 
+/// How far the effect stack reaches into a cache key. [`EffectScope::Footprint`] keys an
+/// adjustment layer's footprint — its source through its masks, without any effects — so the
+/// stack must not reach the key at all (#687).
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub(super) enum EffectScope {
+    /// The whole stack (the processed layer).
+    All,
+    /// Only the first `n` effects (a layer's input, see [`input_key`]).
+    First(usize),
+    /// None of it (an adjustment layer's footprint).
+    Footprint,
+}
+
 /// Cache key for an adjustment layer's footprint (its source through its masks, see
 /// `Renderer::adjustment_footprint`): the GPU compositor then uploads it once, not every frame.
 pub fn footprint_key(ctx: &EvalCtx, layer: &Layer, scale: f64, draft: bool, blur: bool) -> Option<u64> {
     // The footprint is the source through the masks, without the effects: a time-dependent
     // effect (Noise on a finishing adjustment layer) must not re-key it every frame (on the GPU,
-    // a full-frame re-upload per frame).
-    Some(derive(key_any(ctx, layer, scale, draft, blur, false, Some(0))?, 0xf007_9417))
+    // a full-frame re-upload per frame). Shutter, paint, the comp scene and effect dependencies
+    // stay out of this key too; a mask still does.
+    Some(derive(key_any(ctx, layer, scale, draft, blur, false, EffectScope::Footprint)?, 0xf007_9417))
 }
 
 fn key_with(ctx: &EvalCtx, layer: &Layer, scale: f64, draft: bool, blur: bool, footage: bool) -> Option<u64> {
     if layer.switches.adjustment {
         return None;
     }
-    key_any(ctx, layer, scale, draft, blur, footage, None)
+    key_any(ctx, layer, scale, draft, blur, footage, EffectScope::All)
 }
 
-/// `blur`: the layer is motion blurred in this render (`Renderer::mb_on`). `effects`: key only
-/// the first that many effects (a layer's input, see [`input_key`]).
-fn key_any(ctx: &EvalCtx, layer: &Layer, scale: f64, draft: bool, blur: bool, footage: bool, effects: Option<usize>) -> Option<u64> {
+/// `blur`: the layer is motion blurred in this render (`Renderer::mb_on`). `effects`: how far
+/// the effect stack reaches into the key (see [`EffectScope`]).
+fn key_any(ctx: &EvalCtx, layer: &Layer, scale: f64, draft: bool, blur: bool, footage: bool, effects: EffectScope) -> Option<u64> {
     let mut h = KeyHasher(0xcbf2_9ce4_8422_2325);
     ctx.comp.frame_rate.as_f64().to_bits().hash(&mut h);
     ctx.comp.enable_frame_blending.hash(&mut h);
@@ -651,8 +665,10 @@ fn key_any(ctx: &EvalCtx, layer: &Layer, scale: f64, draft: bool, blur: bool, fo
     // (Audio, Lock and Shy don't change pixels.)
     hash_debug(&mut h, &layer.switches.pixels());
     // Mask motion blur and effects that read the shutter depend on whether the layer is motion
-    // blurred in this render and on the comp's shutter.
-    if layer.masks().is_some_and(|m| !m.children.is_empty()) || layer.effects().is_some_and(|fx| !fx.children.is_empty()) {
+    // blurred in this render and on the comp's shutter. A footprint has no effects, so only its
+    // masks put the shutter in the key.
+    if layer.masks().is_some_and(|m| !m.children.is_empty()) || (effects != EffectScope::Footprint && layer.effects().is_some_and(|fx| !fx.children.is_empty()))
+    {
         blur.hash(&mut h);
         ctx.comp.enable_motion_blur.hash(&mut h);
         ctx.comp.shutter_angle.to_bits().hash(&mut h);
@@ -666,23 +682,29 @@ fn key_any(ctx: &EvalCtx, layer: &Layer, scale: f64, draft: bool, blur: bool, fo
         {
             continue;
         }
+        // A footprint is its source through its masks: the effect stack is not in it at all.
         // A layer's input runs only its first effects: the later ones (a Puppet whose pins are
         // dragged, #212) don't change it, so it stays cached.
-        if let (Some(n), Node::Group(g)) = (effects, c)
+        if let Node::Group(g) = c
             && g.match_id == "effects"
         {
-            let mut first = g.clone();
-            let mut seen = 0;
-            first.children.retain(|e| match e {
-                Node::Prop(_) => true,
-                Node::Group(_) => {
-                    seen += 1;
-                    seen <= n
-                }
-            });
-            hash_debug(&mut h, &first);
-            hash_values(&mut h, ctx, layer, &first);
-            continue;
+            if effects == EffectScope::Footprint {
+                continue;
+            }
+            if let EffectScope::First(n) = effects {
+                let mut first = g.clone();
+                let mut seen = 0;
+                first.children.retain(|e| match e {
+                    Node::Prop(_) => true,
+                    Node::Group(_) => {
+                        seen += 1;
+                        seen <= n
+                    }
+                });
+                hash_debug(&mut h, &first);
+                hash_values(&mut h, ctx, layer, &first);
+                continue;
+            }
         }
         // Static structure: values, keyframes, expressions, enabled flags, effect ids, modes.
         hash_debug(&mut h, c);
@@ -691,7 +713,9 @@ fn key_any(ctx: &EvalCtx, layer: &Layer, scale: f64, draft: bool, blur: bool, fo
         }
     }
     // Paint strokes appear and disappear with their Duration spans (not property values).
-    if layer.switches.effects
+    // A footprint does not include them.
+    if effects != EffectScope::Footprint
+        && layer.switches.effects
         && let Some(fx) = layer.effects()
     {
         let lt = layer.layer_time(ctx.time).seconds();
@@ -704,14 +728,14 @@ fn key_any(ctx: &EvalCtx, layer: &Layer, scale: f64, draft: bool, blur: bool, fo
     if mask_motion_blur(ctx, layer, blur) {
         layer.layer_time(ctx.time).0.hash(&mut h);
     }
-    if time_dependent(layer, effects != Some(0)) {
+    if time_dependent(layer, effects != EffectScope::Footprint) {
         layer.layer_time(ctx.time).0.hash(&mut h);
         // Effects also see the layer's time mapping.
         layer.start_time.0.hash(&mut h);
         layer.stretch.to_bits().hash(&mut h);
     }
     // Effects that see the comp camera or lights (#397) change when they or the layer move.
-    if reads_comp_scene(layer) {
+    if effects != EffectScope::Footprint && reads_comp_scene(layer) {
         hash_debug(&mut h, &crate::comp_scene(ctx, layer));
     }
     Some(h.finish())
diff --git a/crates/render/src/cache/dependencies.rs b/crates/render/src/cache/dependencies.rs
index 1a550f9c7..2019d858a 100644
--- a/crates/render/src/cache/dependencies.rs
+++ b/crates/render/src/cache/dependencies.rs
@@ -6,9 +6,15 @@ use crate::EvalCtx;
 use effectcraft_project::{ItemId, ItemKind, Layer, LayerId, LayerSource, LightKind, Node, PropGroup};
 use std::hash::Hash;
 
-pub(super) fn hash(h: &mut KeyHasher, ctx: &EvalCtx, layer: &Layer, effects: Option<usize>) -> Option<()> {
+pub(super) fn hash(h: &mut KeyHasher, ctx: &EvalCtx, layer: &Layer, effects: super::EffectScope) -> Option<()> {
+    // A footprint runs no effects: nothing they read is in its pixels or its key.
+    let limit = match effects {
+        super::EffectScope::Footprint => return Some(()),
+        super::EffectScope::All => None,
+        super::EffectScope::First(n) => Some(n),
+    };
     let mut deps = Dependencies { h, path: vec![(ctx.comp_id, layer.id)], remaining: 1024, other_times: super::reads_other_times(layer, None) };
-    deps.effects(ctx, layer, effects)
+    deps.effects(ctx, layer, limit)
 }
 
 struct Dependencies<'a> {
diff --git a/crates/render/src/tests.rs b/crates/render/src/tests.rs
index 488f38ec7..9ab94ebfb 100644
--- a/crates/render/src/tests.rs
+++ b/crates/render/src/tests.rs
@@ -903,6 +903,54 @@ fn default_effect_points_sit_at_the_centre_of_a_shape_layer() {
     }
 }
 
+/// #687: an adjustment layer's footprint (its source through its masks) must not be keyed by
+/// its effect stack. Noise on a finishing adjustment changes every frame, and letting that
+/// reach the key re-rendered and re-uploaded a full-frame buffer every frame. A moving mask
+/// must still re-key it, and the cached buffer must follow the mask.
+#[test]
+fn adjustment_footprint_key_ignores_the_effect_stack() {
+    let (mut p, cid, comp) = setup();
+    let mut adj = solid(&mut p, &comp, [1.0, 1.0, 1.0], 200, 100);
+    adj.switches.adjustment = true;
+    add_effect_200(&mut p, &mut adj, "ec.noise.noise", &[("amount", Value::Scalar(50.0))]);
+    let key = |p: &Project, t: f64| {
+        let c = p.comp(cid).unwrap();
+        crate::cache::footprint_key(&crate::EvalCtx::new(p, cid, c, Tick::from_seconds_f64(t)), &c.layers[0], 1.0, false, false).unwrap()
+    };
+    let mut next = p.next_id;
+    let mut m = build::mask(&mut Ids(&mut next), "Mask 1", ShapePath::rect([50.0, 50.0], 40.0, 40.0), MaskMode::Add, [255, 255, 0]);
+    p.next_id = next;
+    m.prop_mut("path").unwrap().keys = vec![
+        Keyframe::new(Tick::ZERO, Value::Path(ShapePath::rect([50.0, 50.0], 40.0, 40.0))),
+        Keyframe::new(Tick::from_seconds_f64(1.0), Value::Path(ShapePath::rect([150.0, 50.0], 40.0, 40.0))),
+    ];
+    // Effects alone must not put the shutter in the footprint key. Masks, added below, may.
+    p.comp_mut(cid).unwrap().layers.push(adj.clone());
+    let bare = key(&p, 0.0);
+    p.comp_mut(cid).unwrap().shutter_angle = 90.0;
+    assert_eq!(bare, key(&p, 0.0), "the comp shutter must not re-key a footprint");
+    p.comp_mut(cid).unwrap().shutter_angle = 180.0;
+    p.comp_mut(cid).unwrap().layers[0].props.sub_mut("masks").unwrap().children.push(m.into());
+    let foot = |p: &Project, t: f64| {
+        let c = p.comp(cid).unwrap();
+        let mut r = crate::Renderer::new(p, &crate::NoFootage, crate::RenderOpts::default());
+        let cache = crate::LayerCache::default();
+        r.cache = Some(&cache);
+        let layer = c.layers[0].clone();
+        let b = r.adjustment_footprint(&crate::EvalCtx::new(p, cid, c, Tick::from_seconds_f64(t)), &layer).unwrap();
+        b.img.get(50, 50)
+    };
+    assert_ne!(key(&p, 0.0), key(&p, 0.5), "an animated mask path must re-key the footprint");
+    assert_ne!(key(&p, 0.0), key(&p, 1.0));
+    assert_ne!(foot(&p, 0.0), foot(&p, 1.0), "the moved mask must reach the cached footprint");
+    assert_eq!(key(&p, 1.0), key(&p, 1.5), "a per-frame effect on the adjustment re-keyed its footprint");
+    assert_eq!(key(&p, 1.0), key(&p, 3.5), "the footprint key followed the clock past the mask");
+    assert_eq!(foot(&p, 1.0), foot(&p, 3.5));
+    let before = key(&p, 0.0);
+    p.comp_mut(cid).unwrap().layers[0].props.prop_mut("effects/#1/amount").unwrap().value = Value::Scalar(90.0);
+    assert_eq!(before, key(&p, 0.0), "editing an effect parameter must not re-key the footprint");
+}
+
 /// #659: a tiling effect on a text layer tiles across the layer's whole region. The glyphs
 /// were cut off at their own bounding box: the effect computed over the comp-sized layer rect
 /// but wrote into the painted (glyph-bounds) buffer alone. Tiling shrinks each copy, so the