diff --git a/docs/superpowers/specs/2026-06-07-reconciled-simulator-alteration-slice-design.md b/docs/superpowers/specs/2026-06-07-reconciled-simulator-alteration-slice-design.md
index 7be4186..103e9ff 100644
--- a/docs/superpowers/specs/2026-06-07-reconciled-simulator-alteration-slice-design.md
+++ b/docs/superpowers/specs/2026-06-07-reconciled-simulator-alteration-slice-design.md
@@ -273,12 +273,26 @@ calibration. The re-bake is a later offline-pipeline task.
 
 ## 8. Open questions (for the plan, not blockers)
 
-- **Calibration curve shape** — the panel exposes the params; the final
-  `DEFAULT_CALIBRATION` values are settled by eye, not fixed here.
-- **Grade vs. Left overlay interaction** — with a runtime overlay the grade need *not*
-  tint the HUD (unlike the baked path); decide in the renderer whether the Left overlay
-  sits above or below the grade. Default: **above** (HUD stays legible regardless of
-  mood). Revisit by eye.
+- **Calibration curve shape** — **RESOLVED (session 0010, by eye).**
+  `DEFAULT_CALIBRATION` is **locked** to unity gains + a linear variant map
+  (`mood_gain=1.0`, `overlay_gain=1.0`, `right_variant_map=(0,1,2,3,4)`), as a
+  deliberate choice: with the dark-grade fix below, full knob is peaceful on
+  every axis (POC + sim), so full tilt = full look and the 5 notches map 1:1 to
+  the 5 discrete Right bakes. This also closes the **session-0006** convention
+  question — knobs run 0=off..4=max, equal Dark/Light = identity; no
+  "centered at 2 = no push." Guarded by `test_default_calibration_is_locked`.
+- **Grade vs. Left overlay interaction** — **RESOLVED: overlay above the grade.**
+  The simulator composites the Left HUD (SVG) above the mood grade and the cool
+  tint, so the HUD stays legible regardless of mood. The Pi renderer should do
+  the same.
+- **Dark-pole grade look** — **FIXED (session 0010).** The first by-eye pass found
+  the sim's dark grade used a full-frame `hue-rotate(-200deg)`, which turned the
+  rock orange and trees purple — the disorienting look rejected in 0008, not the
+  peaceful POC `dark_frame`. Replaced with darken + slight desaturate on the video
+  filter plus a `multiply`-blended deep-blue wash (`#tint`) that lifts shadows
+  toward blue while preserving natural greens. The Pi renderer (later slice) will
+  do proper grading; this matches the approved POC dark look closely enough to tune
+  by eye in the sim.
 - **Crossfade timing in the browser** — a simple opacity crossfade is enough for tuning;
   the real timing engine is a later slice.
 - **Placeholder fidelity** — how close the strength-1–3 placeholders should look to real
diff --git a/player/alteration.py b/player/alteration.py
index 4a1b045..d343367 100644
--- a/player/alteration.py
+++ b/player/alteration.py
@@ -42,7 +42,25 @@ class Calibration:
     right_variant_map: tuple = (0, 1, 2, 3, 4)
 
 
-DEFAULT_CALIBRATION = Calibration()
+# The LOCKED calibration (session 0010, 2026-06-07) — settled by eye in the
+# simulator, closing the open session-0006 knob->strength decision. Convention:
+# every experience knob runs 0 = off .. 4 = max, and equal Dark/Light = identity
+# (raw footage); there is no "centered at 2 = no push" coordinate.
+#   - mood_gain = 1.0: full Dark/Light knob reaches the full mood grade. By-eye
+#     evidence (POC renders + sim, after the dark-grade fix this session) shows
+#     full tilt is peaceful on every axis, so no softening is warranted.
+#   - overlay_gain = 1.0: full Left = opacity 1.0; the HUD is legible, not
+#     overwhelming, sitting above the grade.
+#   - right_variant_map linear: the 5 knob notches map 1:1 onto the 5 discrete
+#     pre-baked Right strengths (0 = raw base).
+# These are unity/linear by deliberate choice, not as placeholders. The curve
+# stays parameterized so a future re-bake or a different feel is one edit away;
+# test_default_calibration_is_locked guards the values from drifting silently.
+DEFAULT_CALIBRATION = Calibration(
+    mood_gain=1.0,
+    overlay_gain=1.0,
+    right_variant_map=(0, 1, 2, 3, 4),
+)
 
 
 @dataclass(frozen=True)
diff --git a/simulator/static/app.js b/simulator/static/app.js
index 3a4b77f..f2cd708 100644
--- a/simulator/static/app.js
+++ b/simulator/static/app.js
@@ -1,7 +1,7 @@
 // Thin renderer: post controls+calibration -> RenderPlan; render grade, Right
 // variant crossfade, and the live Left overlay. All math stays in Python.
 const $ = (id) => document.getElementById(id);
-const vid = $("vid"), overlay = $("overlay"), black = $("black"), readout = $("readout");
+const vid = $("vid"), tint = $("tint"), overlay = $("overlay"), black = $("black"), readout = $("readout");
 
 let clip = null;           // active clip manifest entry
 let currentVariant = -1;   // last loaded Right strength
@@ -19,12 +19,16 @@ function variantFile(strength) {
 }
 
 function applyGrade(tone) {
-  // Light: warm + brighten; Dark: cool + darken; 0: raw.
+  // Light: warm + brighten (sepia). Dark: cool + darken via a multiply-blended
+  // blue wash (#tint) that lifts shadows toward blue while keeping natural
+  // greens — the peaceful POC dark look, NOT a full-frame hue spin.
   const warm = tone > 0 ? tone : 0, cool = tone < 0 ? -tone : 0;
-  const bright = 1 + 0.25 * tone, sat = 1 + 0.15 * Math.abs(tone);
+  const bright = 1 + 0.25 * warm - 0.35 * cool;
+  const sat = 1 + 0.15 * warm - 0.30 * cool;
   vid.style.filter =
-    `brightness(${bright}) saturate(${sat}) ` +
-    `sepia(${(warm * 0.5).toFixed(3)}) hue-rotate(${(-cool * 200).toFixed(0)}deg)`;
+    `brightness(${bright.toFixed(3)}) saturate(${sat.toFixed(3)}) ` +
+    `sepia(${(warm * 0.5).toFixed(3)})`;
+  tint.style.opacity = (cool * 0.6).toFixed(3);
 }
 
 function loadVariant(strength) {
diff --git a/simulator/static/index.html b/simulator/static/index.html
index c868754..df5eaf8 100644
--- a/simulator/static/index.html
+++ b/simulator/static/index.html
@@ -12,6 +12,7 @@
     <section class="stage">
       <div class="screen">
         <video id="vid" loop muted playsinline></video>
+        <div id="tint"></div>
         <svg id="overlay" viewBox="0 0 100 100" preserveAspectRatio="none"></svg>
         <div id="black" class="black hidden"></div>
       </div>
diff --git a/simulator/static/style.css b/simulator/static/style.css
index 66daf67..5d6bd46 100644
--- a/simulator/static/style.css
+++ b/simulator/static/style.css
@@ -7,6 +7,9 @@ main { display: flex; gap: 1rem; padding: 1rem; flex-wrap: wrap; }
 .screen { position: relative; width: 100%; aspect-ratio: 16 / 9; background: #000;
           border-radius: 6px; overflow: hidden; }
 #vid { width: 100%; height: 100%; object-fit: cover; transition: opacity 0.15s ease; }
+#tint { position: absolute; inset: 0; pointer-events: none; opacity: 0;
+        background: #28425f; mix-blend-mode: multiply;
+        transition: opacity 0.2s ease; }
 #overlay { position: absolute; inset: 0; width: 100%; height: 100%;
            pointer-events: none; transition: opacity 0.2s ease; }
 .anno-box { fill: none; stroke: #6cf; stroke-width: 0.4; vector-effect: non-scaling-stroke; }
diff --git a/tests/test_player_alteration.py b/tests/test_player_alteration.py
index 01509f4..051916d 100644
--- a/tests/test_player_alteration.py
+++ b/tests/test_player_alteration.py
@@ -77,6 +77,16 @@ def test_whole_brain_dark_corner_stacks_grade_substrate_and_overlay():
     assert not plan.is_identity
 
 
+def test_default_calibration_is_locked():
+    # Session 0010: the knob->strength calibration is LOCKED to these values,
+    # settled by eye in the simulator (closes the open session-0006 decision).
+    # This pins the literal constants so they can't drift silently; changing the
+    # locked feel is a deliberate edit here + in alteration.py.
+    assert DEFAULT_CALIBRATION.mood_gain == 1.0
+    assert DEFAULT_CALIBRATION.overlay_gain == 1.0
+    assert DEFAULT_CALIBRATION.right_variant_map == (0, 1, 2, 3, 4)
+
+
 def test_default_calibration_is_behavior_preserving():
     # DEFAULT_CALIBRATION must reproduce the original three helpers exactly.
     for left in range(5):