sampling: check the values where they are used, not only where they are made

The NaN guard was on one of two doors. A FUNPACK_SETTINGS socket is typed by
a string tag, so a dict reaches the load node without necessarily having
passed through the settings node -- a raw API prompt does exactly that.

Through that door, until_sigma = NaN made ALG a permanent no-op: sigma > nan
is False at every step, so the anchor was never loosened, and the node
reported "1 modifier applied: alg". Nothing about the run looked wrong,
which is the only reason this is worth a commit of its own.

Values are now checked against the declaration at the point they are
consumed. The producer still checks too; that is not redundant, it is where
a person editing JSON gets told immediately.

Also recorded ALG's standing assumption rather than leaving it implicit: the
anchor is latent frame 0. True of everything it can currently be wired into,
untrue in general, and the denoise_mask already carries what would be needed
to do it properly. Left undone because nothing yet pins elsewhere, and a
derivation with no consumer cannot be checked against reality.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

modules/sampling/alg/__init__.py

@@ -13,6 +13,15 @@ of its own. It attaches to the MODEL, so it applies to whatever sampler is wired
 H3" -- it needs a latent with a time axis and a pinned anchor, and any model with
 both gets it, including ones nobody here has heard of.
 
+KNOWN ASSUMPTION: the anchor is latent frame 0. That is true of every i2v setup
+this can currently be wired into, and it is what v4 assumed. It is NOT true in
+general -- H3 can pin a keyframe at any frame -- so if an interior-pin mechanism
+is ever ported, ALG must take the frame indices from the pin rather than assume
+the first. The information to do it properly is already present in the
+denoise_mask, which is what marks the locked frames; deriving from it is left
+undone deliberately, because there is nothing yet that pins anywhere else and a
+derivation with no consumer cannot be checked against reality.
+
 What is NOT ported from v4: the packed-layout path, which reached into a
 model-specific arrangement of the latent to find the video stream. Where the
 anchor is not a plain [B, C, T, H, W] tensor this stands down and says so once,

modules/sampling/alg/tests/test_alg.py

@@ -159,3 +159,12 @@ def test_the_proxy_is_transparent_for_everything_else():
     assert proxy.inner_model == "the real model"
     proxy.something = 7
     assert inner.something == 7, "an assignment did not reach the real denoiser"
+
+
+def test_a_threshold_that_is_not_a_number_would_disable_it_everywhere():
+    """Why the check at the load node matters, in ALG's own terms. NaN compares
+    False against every sigma, so the anchor is never loosened at any step --
+    and nothing about the run looks wrong."""
+    from modules.sampling.alg.blur import use_blurred
+    assert all(use_blurred(sigma, float("nan")) is False
+               for sigma in (0.99, 0.5, 0.01))

modules/sampling/modifiers/nodes.py

@@ -163,8 +163,24 @@ class FunPackLoadModifiers(io.ComfyNode):
         if stripped:
             notes.append(f"replaced {stripped} modifier(s) already on this model")
 
+        # Checked HERE, not only where the payload was made. A FUNPACK_SETTINGS
+        # socket is typed by a string tag, so a dict can reach this node without
+        # ever passing through FunPackModifierSettings -- a raw API prompt, or a
+        # second producer of that type. Validating only at the producer is a
+        # guard on one of two doors, and the one left open let NaN through:
+        # `sigma > nan` is False at every step, so a modifier became a permanent
+        # no-op while reporting that it had been applied.
+        problems = []
+        chosen = {}
         for spec in ordered:
-            values = (settings or {}).get(spec.id) or spec.defaults()
+            values, said = schema_mod.check_values(spec, (settings or {}).get(spec.id))
+            chosen[spec.id] = values
+            problems.extend(said)
+        if problems:
+            raise RuntimeError("FunPack Load Modifiers:\n  " + "\n  ".join(problems))
+
+        for spec in ordered:
+            values = chosen[spec.id]
             install = spec.provides[CAPABILITY]
             try:
                 note = install(patched, values, key=KEY_PREFIX + spec.id)

modules/sampling/tests/test_modifiers.py

@@ -252,3 +252,37 @@ def test_a_settings_payload_of_the_wrong_shape_is_refused_clearly(registry, patc
 
     with pytest.raises(RuntimeError, match="keyed by module id"):
         FunPackLoadModifiers.execute(patcher, settings=["not", "a", "dict"])
+
+
+def test_values_are_checked_where_they_are_used_not_only_where_they_were_made(registry, patcher):
+    """The settings socket is typed by a string tag, so a dict can reach this
+    node without passing through FunPackModifierSettings. Validating only at the
+    producer guards one of two doors, and NaN walked through the other: sigma >
+    nan is False at every step, so the modifier became a permanent no-op while
+    reporting that it had been applied."""
+    from modules.sampling.modifiers.nodes import FunPackLoadModifiers
+
+    registry.specs["alg"] = _spec("alg", lambda t, v, key: "on", settings={
+        "until_sigma": {"type": "float", "default": 0.6, "min": 0.0, "max": 1.0, "label": "T"},
+    })
+
+    with pytest.raises(RuntimeError, match="finite"):
+        FunPackLoadModifiers.execute(patcher, settings={"alg": {"until_sigma": float("nan")}})
+
+
+def test_an_out_of_range_value_is_refused_at_this_node_too(registry, patcher):
+    from modules.sampling.modifiers.nodes import FunPackLoadModifiers
+    registry.specs["alg"] = _spec("alg", lambda t, v, key: "on", settings={
+        "strength": {"type": "float", "default": 4.0, "min": 1.0, "max": 16.0, "label": "S"},
+    })
+    with pytest.raises(RuntimeError, match="above its maximum"):
+        FunPackLoadModifiers.execute(patcher, settings={"alg": {"strength": 99.0}})
+
+
+def test_a_setting_no_module_declares_is_refused_at_this_node_too(registry, patcher):
+    from modules.sampling.modifiers.nodes import FunPackLoadModifiers
+    registry.specs["alg"] = _spec("alg", lambda t, v, key: "on", settings={
+        "strength": {"type": "float", "default": 4.0, "min": 1.0, "max": 16.0, "label": "S"},
+    })
+    with pytest.raises(RuntimeError, match="no setting named"):
+        FunPackLoadModifiers.execute(patcher, settings={"alg": {"strenght": 4.0}})