docs(spec): simulator alteration preview design (session 0007)

Bring the slice-1 alteration engine into the simulator so the experience
look can be tuned before hardware (operator simulator-first directive).
Python-canonical engine, thin browser renderer; Dark/Light as a live
runtime grade, Left/Right as a 5x5 grid of pre-baked authored variant
clips selected by coordinate.

Revises the machine-altered-perception design SS4.3/SS10: the Left HUD is
now baked into authored variant videos (authorial precision over the HUD)
rather than a runtime overlay, trading away near-free multilingual support.
Retires the simulator's selection-era X-ray view + endpoints.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/ROADMAP.md

@@ -15,7 +15,7 @@ Design reference: [`specs/2026-06-04-human-experience-filter-design.md`](./super
 |---|---------------------------------|---------------|----------|
 | 1 | Catalog & Selection Core        | ✅ Done        | everything |
 | 2 | Ingest & Tagging / Review tools | ✅ Done        | a real library |
-| 3 | Player Runtime (Pi)             | ⏳ Next        | the room runs |
+| 3 | Player Runtime (Pi)             | ⏳ In progress | the room runs |
 | 4 | Arduino Firmware (control panel)| ◻ Not started | real knobs |
 | 5 | ~~Procedural Side Walls~~       | ❌ Dropped     | — (superseded) |
 
@@ -95,29 +95,60 @@ was `validate_catalog` + `index_by_id`.
 
 ---
 
-## 3. Player Runtime (Pi) ⏳ (next)
+## 3. Player Runtime (Pi) ⏳ (in progress)
 
-**Goal:** the thing that makes the room run — read the controls, pick media, play
-it across the single panoramic projector.
+**Goal:** the thing that makes the room run — read the controls, **alter** the
+neutral base footage toward the knob state, and play it across the single
+panoramic projector. Per the machine-altered-perception revision the knobs no
+longer *select* a pre-tagged clip; they drive an **alteration engine** (design
+§4/§5) over a small neutral base library.
 
-**Delivers (`player/`):**
+**Slice 1 — alteration engine + player core (pure logic) ✅ Done.** Merged to
+`main` (session 0006); 56 tests. The new `player/` package, with all I/O
+(video/audio/serial) behind injected interfaces:
 
-- Read the five control values from the Arduino over USB serial.
-- Call `hef.selection.select()` on each change; loop the chosen 5–15 min segment
-  until the knobs move; **crossfade** on change.
-- `None` mode → fade to black + silence.
-- Drive the **single panoramic projector** spanning the three walls with the real
-  selected video (no primary/side split; no side-wall feed — sub-project 5 dropped).
+- `player/controls.py` — `Controls`, the full panel state (7-way content dial +
+  4 experience knobs + volume + brightness); the serial-contract data shape
+  shared with sub-project 4.
+- `player/content.py` — `resolve_content`, the §6 7-way dial → (audio source,
+  video on/off) table.
+- `player/alteration.py` — `plan_alteration`, knob vector → `RenderPlan`
+  (mood `ColorGrade` with center=identity §5; Left `AnalyticalOverlay`; Right
+  `Restyle`), encoding the §4.2 layering rule (substrate vs overlay; Left & Right
+  stack).
+- `player/state.py` — `Player`, the state machine that diffs successive controls
+  into transitions (`FADE_TO_BLACK`/`FADE_FROM_BLACK` on video on/off,
+  `CROSSFADE` on clip/restyle-variant swap, `LIVE_UPDATE` for the continuous
+  grade/overlay/level ops per §4.3, `NONE` when unchanged).
 
-**Depends on:** sub-project 1 (`select`); a populated catalog from sub-project 2
-to be meaningful, but can be developed against a hand-authored catalog and a
-**keyboard/serial stand-in** before firmware exists.
-**Done when:** given a catalog and a stream of control values, it plays the
-correct segment, loops, crossfades, and goes dark on `None` — testable with the
-serial input mocked.
-**Hardware:** Raspberry Pi 5 (holds the drive + catalog).
+Plan: [`2026-06-05-player-alteration-core.md`](./superpowers/plans/2026-06-05-player-alteration-core.md).
+
+**Remaining slices (not started):**
+
+- **Runtime renderer** — drive the single panoramic projector via mpv/ffmpeg;
+  GPU shaders for the luma-keyed mood grade + analytical-overlay compositing;
+  realize crossfade/fade timing and the 5–15 min loop. (Open decision: player
+  stack — mpv via IPC vs. ffmpeg vs. custom.)
+- **Serial input** — real USB-serial reader on the Pi + the **3⇄4 framing
+  contract** with the firmware (the keyboard/serial stand-in already works via a
+  `Controls` stream).
+- **White-noise generation** — runtime white/pink noise for that content position.
+- **Offline v2v variant pipeline** — author the pre-baked Right restyle variants
+  (the only paid AI step, design §9) + the multilingual label/string tables + TTS.
+- **Catalog model changes** — audio *source* + "neutral base" vs "altered
+  variant" flag (sub-project 2 territory, design §13).
+
+**Depends on:** sub-project 1 (`Coordinate`); a neutral base library from
+sub-project 2 to be meaningful, but developable against a hand-authored library
+and a **keyboard/serial stand-in** before firmware exists.
+**Done when:** given a base library and a stream of control values, it plays the
+correct altered segment, loops, crossfades, and goes dark on `Off` — the
+decision logic is covered (slice 1, serial mocked); the renderer realizes it.
+**Hardware:** Raspberry Pi 5 (holds the drive + base library + variants).
 **Open decisions:** player stack (mpv via IPC vs. ffmpeg vs. custom); whether the
-player hard-restricts to `approved` records.
+player hard-restricts to `approved` records (the `approved_only` flag is plumbed
+but inert until backed by a real catalog); knob→strength calibration (the §3 vs
+§4.2/§5 reconciliation — see the slice-1 plan / session 0006 transcript).
 
 ---
 

docs/superpowers/plans/2026-06-05-player-alteration-core.md

@@ -0,0 +1,867 @@
+# Player Alteration Core Implementation Plan
+
+> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** Build the pure-logic core of sub-project 3 (the Player Runtime + alteration engine) — a new `player/` package that turns control-panel state into a render plan and playback transitions, fully unit-tested with all I/O (video/audio/serial) behind injected interfaces.
+
+**Architecture:** Four small, pure modules mirroring `hef/` conventions (frozen dataclasses, `from __future__ import annotations`, string-constant frozensets, thorough unit tests, no heavy deps). `controls` models the panel state (the serial-contract data shape shared with sub-project 4); `content` resolves the 7-way content dial; `alteration` is the heart — knob vector → `RenderPlan` per design §4/§5; `state` is the player state machine that diffs successive controls into playback transitions (crossfade / fade-to-black / live-update). No mpv, no GPU, no real serial, no white-noise DSP, no v2v pipeline — those are later integration slices.
+
+**Tech Stack:** Python 3.11+, stdlib only (`dataclasses`, `math`), pytest. Reuses `hef.selection.Coordinate` for the knob vector.
+
+**Design reference:** `docs/superpowers/specs/2026-06-05-machine-altered-perception-design.md` (§4 alteration engine, §5 mood grade, §6 7-way content dial, §7 intensity) and `docs/ROADMAP.md` §3 (Player Runtime "done when").
+
+**Calibration decision (flagged for operator):** brain knobs use `strength = value/4` (0=off, 4=max); mood uses `tone = (light−dark)/4` (equal dark/light = identity per §5). This reads §3's "(2,2,2,2) neutral" as a vestige of the old coordinate-grid center. The calibration lives in three one-line helpers so the convention can be flipped trivially. See the session 0006 transcript's Deferred decisions.
+
+---
+
+## File Structure
+
+- `player/__init__.py` — package marker (empty).
+- `player/controls.py` — `Controls` frozen dataclass (content position + 4 experience knobs + volume + brightness), `CONTENT_POSITIONS`, `validate_controls`, `parse_controls` (from a decoded mapping; wire framing is the separate 3⇄4 serial contract).
+- `player/content.py` — `ContentResolution` (audio source + video flag), `AUDIO_SOURCES`, `resolve_content` (the §6 7-row table, single source of truth).
+- `player/alteration.py` — `ColorGrade`, `AnalyticalOverlay`, `Restyle`, `RenderPlan`, `plan_alteration(coord)`, and the calibration helpers `_overlay_intensity`, `_restyle_blend`, `_mood_tone`.
+- `player/state.py` — `Playback`, `TransitionKind`, `Transition`, `Player` (consumes a stream of `Controls`, emits a `Transition` per update; output sink is injected/duck-typed; base-clip choice is an injected callable).
+- `pyproject.toml` — add `"player"` to `[tool.setuptools] packages`.
+
+Tests (one per module): `tests/test_player_controls.py`, `tests/test_player_content.py`, `tests/test_player_alteration.py`, `tests/test_player_state.py`.
+
+---
+
+## Task 1: Controls model (the serial-contract data shape)
+
+**Files:**
+- Create: `player/__init__.py`
+- Create: `player/controls.py`
+- Test: `tests/test_player_controls.py`
+
+- [ ] **Step 1: Write the failing tests**
+
+```python
+# tests/test_player_controls.py
+import pytest
+
+from player.controls import (
+    Controls,
+    CONTENT_POSITIONS,
+    ControlsError,
+    validate_controls,
+    parse_controls,
+)
+
+
+def test_content_positions_are_the_seven_from_the_spec():
+    assert CONTENT_POSITIONS == frozenset(
+        {"off", "white_noise", "music", "audio_track", "video", "music_video", "audio_video"}
+    )
+
+
+def test_valid_controls_pass_validation():
+    c = Controls(content="video", left=0, right=4, dark=2, light=2, volume=3, brightness=4)
+    validate_controls(c)  # does not raise
+
+
+def test_invalid_content_position_rejected():
+    c = Controls(content="bogus", left=0, right=0, dark=0, light=0, volume=0, brightness=0)
+    with pytest.raises(ControlsError):
+        validate_controls(c)
+
+
+@pytest.mark.parametrize("field", ["left", "right", "dark", "light", "volume", "brightness"])
+@pytest.mark.parametrize("bad", [-1, 5, True])
+def test_out_of_range_or_non_int_knob_rejected(field, bad):
+    kwargs = dict(content="off", left=0, right=0, dark=0, light=0, volume=0, brightness=0)
+    kwargs[field] = bad
+    with pytest.raises(ControlsError):
+        validate_controls(Controls(**kwargs))
+
+
+def test_parse_controls_from_mapping():
+    c = parse_controls(
+        {"content": "music_video", "left": 1, "right": 2, "dark": 3, "light": 0, "volume": 2, "brightness": 1}
+    )
+    assert c == Controls("music_video", 1, 2, 3, 0, 2, 1)
+
+
+def test_parse_controls_rejects_unknown_keys():
+    with pytest.raises(ControlsError):
+        parse_controls({"content": "off", "left": 0, "right": 0, "dark": 0,
+                        "light": 0, "volume": 0, "brightness": 0, "bogus": 1})
+
+
+def test_parse_controls_rejects_missing_keys():
+    with pytest.raises(ControlsError):
+        parse_controls({"content": "off", "left": 0})
+```
+
+- [ ] **Step 2: Run tests to verify they fail**
+
+Run: `pytest tests/test_player_controls.py -v`
+Expected: FAIL with `ModuleNotFoundError: No module named 'player'`.
+
+- [ ] **Step 3: Write minimal implementation**
+
+```python
+# player/__init__.py
+```
+(empty file)
+
+```python
+# player/controls.py
+"""Control-panel state: the data shape read from the Arduino over serial.
+
+This is the serial-contract payload shared with sub-project 4 (firmware). It
+models the full panel from design §6/§7: the 7-way content dial, the four
+experience knobs (0..4), and the two intensity levels (volume, brightness).
+The wire framing itself is the separate 3<->4 serial contract; this module is
+the *decoded* form.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass, fields
+
+# The seven positions of the content dial (design §6).
+CONTENT_POSITIONS = frozenset(
+    {"off", "white_noise", "music", "audio_track", "video", "music_video", "audio_video"}
+)
+
+KNOB_FIELDS = ("left", "right", "dark", "light", "volume", "brightness")
+KNOB_MIN = 0
+KNOB_MAX = 4
+
+
+class ControlsError(ValueError):
+    """Raised when a Controls payload is structurally invalid."""
+
+
+@dataclass(frozen=True)
+class Controls:
+    content: str
+    left: int
+    right: int
+    dark: int
+    light: int
+    volume: int
+    brightness: int
+
+
+def validate_controls(c: Controls) -> None:
+    """Raise ControlsError if the payload is structurally invalid."""
+    if c.content not in CONTENT_POSITIONS:
+        raise ControlsError(
+            f"invalid content position {c.content!r}; "
+            f"expected one of {sorted(CONTENT_POSITIONS)}"
+        )
+    for name in KNOB_FIELDS:
+        value = getattr(c, name)
+        if isinstance(value, bool) or not isinstance(value, int):
+            raise ControlsError(f"knob {name} must be an int, got {value!r}")
+        if not (KNOB_MIN <= value <= KNOB_MAX):
+            raise ControlsError(
+                f"knob {name}={value} out of range {KNOB_MIN}..{KNOB_MAX}"
+            )
+
+
+def parse_controls(data: dict) -> Controls:
+    """Build a validated Controls from a decoded mapping, rejecting unknown or
+    missing keys."""
+    known = {f.name for f in fields(Controls)}
+    unknown = set(data) - known
+    if unknown:
+        raise ControlsError(f"unknown keys: {sorted(unknown)}")
+    missing = known - set(data)
+    if missing:
+        raise ControlsError(f"missing keys: {sorted(missing)}")
+    c = Controls(**data)
+    validate_controls(c)
+    return c
+```
+
+- [ ] **Step 4: Run tests to verify they pass**
+
+Run: `pytest tests/test_player_controls.py -v`
+Expected: PASS (all cases).
+
+- [ ] **Step 5: Commit**
+
+```bash
+git add player/__init__.py player/controls.py tests/test_player_controls.py
+git commit -m "feat(player): Controls panel model (serial-contract data shape)
+
+Sub-project 3 slice 1, per ROADMAP.md §3 and design §6/§7."
+```
+
+---
+
+## Task 2: Content-dial resolution (§6)
+
+**Files:**
+- Create: `player/content.py`
+- Test: `tests/test_player_content.py`
+
+- [ ] **Step 1: Write the failing tests**
+
+```python
+# tests/test_player_content.py
+import pytest
+
+from player.content import AUDIO_SOURCES, ContentResolution, resolve_content
+
+
+def test_audio_sources_are_the_four_distinct_sources():
+    assert AUDIO_SOURCES == frozenset({"none", "white_noise", "music", "audio_track"})
+
+
+# The §6 table, row by row: position -> (audio_source, video).
+@pytest.mark.parametrize(
+    "position,audio_source,video",
+    [
+        ("off", "none", False),
+        ("white_noise", "white_noise", False),
+        ("music", "music", False),
+        ("audio_track", "audio_track", False),
+        ("video", "none", True),
+        ("music_video", "music", True),
+        ("audio_video", "audio_track", True),
+    ],
+)
+def test_resolve_content_matches_spec_table(position, audio_source, video):
+    assert resolve_content(position) == ContentResolution(audio_source=audio_source, video=video)
+
+
+def test_off_is_void_state_black_and_silent():
+    r = resolve_content("off")
+    assert r.video is False and r.audio_source == "none"
+
+
+def test_resolve_content_rejects_unknown_position():
+    with pytest.raises(ValueError):
+        resolve_content("bogus")
+```
+
+- [ ] **Step 2: Run tests to verify they fail**
+
+Run: `pytest tests/test_player_content.py -v`
+Expected: FAIL with `ModuleNotFoundError: No module named 'player.content'`.
+
+- [ ] **Step 3: Write minimal implementation**
+
+```python
+# player/content.py
+"""Resolve the 7-way content dial into an audio source + video on/off (§6).
+
+The single source of truth for design §6's table: which audio source plays and
+whether the projector shows video, for each dial position.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+# The four distinct audio sources. "white_noise" is generated at runtime;
+# "music" is the public-domain classical pool; "audio_track" is the clip's own
+# field audio; "none" is silence.
+AUDIO_SOURCES = frozenset({"none", "white_noise", "music", "audio_track"})
+
+
+@dataclass(frozen=True)
+class ContentResolution:
+    audio_source: str
+    video: bool
+
+
+# Design §6, one row per dial position.
+_TABLE = {
+    "off": ContentResolution("none", False),
+    "white_noise": ContentResolution("white_noise", False),
+    "music": ContentResolution("music", False),
+    "audio_track": ContentResolution("audio_track", False),
+    "video": ContentResolution("none", True),
+    "music_video": ContentResolution("music", True),
+    "audio_video": ContentResolution("audio_track", True),
+}
+
+
+def resolve_content(position: str) -> ContentResolution:
+    """Map a content-dial position to its audio source and video flag (§6)."""
+    try:
+        return _TABLE[position]
+    except KeyError:
+        raise ValueError(
+            f"unknown content position {position!r}; expected one of {sorted(_TABLE)}"
+        ) from None
+```
+
+- [ ] **Step 4: Run tests to verify they pass**
+
+Run: `pytest tests/test_player_content.py -v`
+Expected: PASS.
+
+- [ ] **Step 5: Commit**
+
+```bash
+git add player/content.py tests/test_player_content.py
+git commit -m "feat(player): 7-way content-dial resolution (design §6)"
+```
+
+---
+
+## Task 3: Alteration engine — knob vector to RenderPlan (§4, §5)
+
+**Files:**
+- Create: `player/alteration.py`
+- Test: `tests/test_player_alteration.py`
+
+The engine maps a knob vector `(left, right, dark, light)` to a layered `RenderPlan` per design §4.2:
+- **Substrate** transforms (alter pixels): `Restyle` (Right, v2v) blended with `ColorGrade` (mood, Dark/Light).
+- **Overlay** on top: `AnalyticalOverlay` (Left, HUD/labels).
+
+`ColorGrade.tone` is signed: `>0` warm yellow→white (light pole), `<0` cool blue→black (dark pole), `0` identity/raw (§5). Calibration (flagged decision): `overlay = left/4`, `restyle = right/4`, `tone = (light − dark)/4`.
+
+- [ ] **Step 1: Write the failing tests**
+
+```python
+# tests/test_player_alteration.py
+import pytest
+
+from hef.selection import Coordinate
+from player.alteration import (
+    AnalyticalOverlay,
+    ColorGrade,
+    RenderPlan,
+    Restyle,
+    plan_alteration,
+)
+
+
+def _coord(left=0, right=0, dark=0, light=0):
+    return Coordinate(left=left, right=right, dark=dark, light=light)
+
+
+def test_all_zero_knobs_is_the_unaltered_base():
+    plan = plan_alteration(_coord())
+    assert plan.is_identity
+    assert plan.overlay.intensity == 0.0
+    assert plan.restyle.blend == 0.0
+    assert plan.grade.tone == 0.0
+    assert plan.grade.is_identity
+
+
+def test_left_drives_the_analytical_overlay_only():
+    plan = plan_alteration(_coord(left=4))
+    assert plan.overlay.intensity == 1.0
+    assert plan.restyle.blend == 0.0  # Left does not touch the substrate
+    assert plan.grade.tone == 0.0
+
+
+def test_right_drives_the_restyle_substrate_only():
+    plan = plan_alteration(_coord(right=2))
+    assert plan.restyle.blend == 0.5
+    assert plan.overlay.intensity == 0.0  # Right does not add overlay
+
+
+def test_left_and_right_stack_not_cancel():
+    # design §4.2: whole-brain corner = dreamlike substrate WITH labels on top
+    plan = plan_alteration(_coord(left=4, right=4))
+    assert plan.overlay.intensity == 1.0
+    assert plan.restyle.blend == 1.0
+
+
+def test_light_pole_grades_warm_positive_tone():
+    plan = plan_alteration(_coord(light=4))
+    assert plan.grade.tone == 1.0
+    assert not plan.grade.is_identity
+
+
+def test_dark_pole_grades_cool_negative_tone():
+    plan = plan_alteration(_coord(dark=4))
+    assert plan.grade.tone == -1.0
+
+
+def test_equal_dark_and_light_is_identity_grade():
+    # design §5: the mood center is the raw, ungraded footage
+    assert plan_alteration(_coord(dark=3, light=3)).grade.is_identity
+    assert plan_alteration(_coord(dark=2, light=2)).grade.is_identity
+
+
+def test_dark_minus_light_sets_intermediate_tone():
+    assert plan_alteration(_coord(dark=4, light=2)).grade.tone == pytest.approx(-0.5)
+    assert plan_alteration(_coord(dark=1, light=3)).grade.tone == pytest.approx(0.5)
+
+
+def test_whole_brain_dark_corner_stacks_grade_substrate_and_overlay():
+    # design §4.2 "Dark + analytical": cold measurement over a melancholy scene
+    plan = plan_alteration(_coord(left=4, right=2, dark=4, light=0))
+    assert plan.overlay.intensity == 1.0
+    assert plan.restyle.blend == 0.5
+    assert plan.grade.tone == -1.0
+    assert not plan.is_identity
+
+
+def test_render_plan_is_frozen():
+    plan = plan_alteration(_coord())
+    with pytest.raises(Exception):
+        plan.grade.tone = 0.5  # type: ignore[misc]
+```
+
+- [ ] **Step 2: Run tests to verify they fail**
+
+Run: `pytest tests/test_player_alteration.py -v`
+Expected: FAIL with `ModuleNotFoundError: No module named 'player.alteration'`.
+
+- [ ] **Step 3: Write minimal implementation**
+
+```python
+# player/alteration.py
+"""The alteration engine: a knob vector -> a layered RenderPlan (design §4, §5).
+
+Replaces the 2026-06-04 nearest-match *selection* with a *transformation* of a
+neutral base clip. Given the four experience knobs, it produces three layers
+that compose per §4.2:
+
+  - Substrate transforms (alter pixels, blend with each other):
+      * Restyle  -- the Right axis: a pre-baked generative v2v dreamlike restyle.
+      * ColorGrade -- the mood axis (Dark/Light): a deterministic color grade.
+  - Overlay (composited on top of the substrate):
+      * AnalyticalOverlay -- the Left axis: HUD/labels/measurement.
+
+Left and Right are NOT opposites; they live on different layers and stack
+(§4.2). Dark and Light are the two poles of one mood grade whose center is the
+identity (§5).
+
+Calibration note: the knob->strength curves below are the single source of
+truth for how a 0..4 position maps to a transform strength. See the session
+0006 transcript Deferred decisions for the §3-vs-§4.2/§5 reconciliation.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+from hef.selection import Coordinate
+
+KNOB_MAX = 4  # knob full-scale (0..4)
+
+
+@dataclass(frozen=True)
+class ColorGrade:
+    """Mood-axis grade (§5). `tone` is signed: >0 warm yellow->white (light),
+    <0 cool blue->black (dark), 0 = identity (raw, ungraded)."""
+
+    tone: float
+
+    @property
+    def is_identity(self) -> bool:
+        return self.tone == 0.0
+
+
+@dataclass(frozen=True)
+class AnalyticalOverlay:
+    """Left axis (§4.1): analytical HUD/annotation/labels, composited on top.
+    `intensity` 0..1 (0 = no overlay)."""
+
+    intensity: float
+
+
+@dataclass(frozen=True)
+class Restyle:
+    """Right axis (§4.1): pre-baked generative v2v dreamlike substrate.
+    `blend` 0..1 (0 = raw substrate, no restyle)."""
+
+    blend: float
+
+
+@dataclass(frozen=True)
+class RenderPlan:
+    """The full layered alteration for one knob vector (§4.2)."""
+
+    grade: ColorGrade
+    overlay: AnalyticalOverlay
+    restyle: Restyle
+
+    @property
+    def is_identity(self) -> bool:
+        """True when the plan leaves the neutral base un-altered."""
+        return (
+            self.grade.is_identity
+            and self.overlay.intensity == 0.0
+            and self.restyle.blend == 0.0
+        )
+
+
+def _overlay_intensity(left: int) -> float:
+    """Left knob -> analytical-overlay intensity (0..1)."""
+    return left / KNOB_MAX
+
+
+def _restyle_blend(right: int) -> float:
+    """Right knob -> v2v restyle blend (0..1)."""
+    return right / KNOB_MAX
+
+
+def _mood_tone(dark: int, light: int) -> float:
+    """(dark, light) -> signed mood grade in [-1, 1]; equal -> 0 identity (§5)."""
+    return (light - dark) / KNOB_MAX
+
+
+def plan_alteration(coord: Coordinate) -> RenderPlan:
+    """Map a knob vector to its layered RenderPlan (design §4)."""
+    return RenderPlan(
+        grade=ColorGrade(tone=_mood_tone(coord.dark, coord.light)),
+        overlay=AnalyticalOverlay(intensity=_overlay_intensity(coord.left)),
+        restyle=Restyle(blend=_restyle_blend(coord.right)),
+    )
+```
+
+- [ ] **Step 4: Run tests to verify they pass**
+
+Run: `pytest tests/test_player_alteration.py -v`
+Expected: PASS.
+
+- [ ] **Step 5: Commit**
+
+```bash
+git add player/alteration.py tests/test_player_alteration.py
+git commit -m "feat(player): alteration engine — knob vector to RenderPlan (design §4/§5)"
+```
+
+---
+
+## Task 4: Player state machine — controls stream to transitions
+
+**Files:**
+- Create: `player/state.py`
+- Test: `tests/test_player_state.py`
+
+The `Player` holds a base-clip library and the current `Playback`. Each `update(controls)` resolves the desired `Playback` (chosen base clip + RenderPlan + content resolution + volume/brightness) and returns the `Transition` from the previous playback:
+
+- target video off, was on → `FADE_TO_BLACK`
+- target video on, was off → `FADE_FROM_BLACK`
+- both video on, clip or restyle variant changed → `CROSSFADE`
+- both video on, only grade/overlay/level changed → `LIVE_UPDATE` (§4.3: grade + overlay are continuous runtime ops)
+- both video off, audio/level changed → `LIVE_UPDATE`
+- nothing changed → `NONE`
+
+Base-clip choice is an injected callable (default: first clip); knobs no longer *select* (the base is neutral) — they *transform*. The library is duck-typed objects with an `.id`.
+
+- [ ] **Step 1: Write the failing tests**
+
+```python
+# tests/test_player_state.py
+from dataclasses import dataclass
+
+import pytest
+
+from player.controls import Controls
+from player.state import Player, Playback, Transition, TransitionKind
+
+
+@dataclass(frozen=True)
+class FakeClip:
+    id: str
+
+
+LIB = [FakeClip("base-a"), FakeClip("base-b")]
+
+
+def _controls(content="video", left=0, right=0, dark=0, light=0, volume=2, brightness=2):
+    return Controls(content, left, right, dark, light, volume, brightness)
+
+
+def test_first_update_to_video_fades_in_from_black():
+    p = Player(LIB)
+    t = p.update(_controls(content="video"))
+    assert t.kind == TransitionKind.FADE_FROM_BLACK
+    assert t.playback.clip_id == "base-a"
+    assert t.playback.content.video is True
+
+
+def test_off_from_video_fades_to_black_and_silences():
+    p = Player(LIB)
+    p.update(_controls(content="video"))
+    t = p.update(_controls(content="off"))
+    assert t.kind == TransitionKind.FADE_TO_BLACK
+    assert t.playback.clip_id is None
+    assert t.playback.content.audio_source == "none"
+
+
+def test_no_change_yields_none_transition():
+    p = Player(LIB)
+    p.update(_controls(content="video", left=1))
+    t = p.update(_controls(content="video", left=1))
+    assert t.kind == TransitionKind.NONE
+
+
+def test_grade_change_is_a_live_update_not_a_crossfade():
+    # design §4.3: the Dark/Light grade is a continuous runtime op
+    p = Player(LIB)
+    p.update(_controls(content="video", dark=0, light=0))
+    t = p.update(_controls(content="video", dark=4, light=0))
+    assert t.kind == TransitionKind.LIVE_UPDATE
+    assert t.playback.plan.grade.tone == -1.0
+
+
+def test_overlay_change_is_a_live_update():
+    p = Player(LIB)
+    p.update(_controls(content="video", left=0))
+    t = p.update(_controls(content="video", left=4))
+    assert t.kind == TransitionKind.LIVE_UPDATE
+    assert t.playback.plan.overlay.intensity == 1.0
+
+
+def test_restyle_change_crossfades_the_substrate():
+    # design §4.3: the Right v2v substrate is a pre-baked variant swap
+    p = Player(LIB)
+    p.update(_controls(content="video", right=0))
+    t = p.update(_controls(content="video", right=4))
+    assert t.kind == TransitionKind.CROSSFADE
+    assert t.playback.plan.restyle.blend == 1.0
+
+
+def test_volume_only_change_is_a_live_update():
+    p = Player(LIB)
+    p.update(_controls(content="video", volume=1))
+    t = p.update(_controls(content="video", volume=4))
+    assert t.kind == TransitionKind.LIVE_UPDATE
+    assert t.playback.volume == 4
+
+
+def test_audio_source_change_while_black_is_a_live_update():
+    p = Player(LIB)
+    p.update(_controls(content="white_noise"))
+    t = p.update(_controls(content="music"))
+    assert t.kind == TransitionKind.LIVE_UPDATE
+    assert t.playback.content.audio_source == "music"
+
+
+def test_injected_base_chooser_is_used():
+    p = Player(LIB, choose_base=lambda lib: lib[1])
+    t = p.update(_controls(content="video"))
+    assert t.playback.clip_id == "base-b"
+
+
+def test_empty_library_with_video_raises():
+    p = Player([])
+    with pytest.raises(ValueError):
+        p.update(_controls(content="video"))
+
+
+def test_off_with_empty_library_is_fine():
+    p = Player([])
+    t = p.update(_controls(content="off"))
+    assert t.kind == TransitionKind.NONE  # already black at init
+    assert t.playback.clip_id is None
+```
+
+- [ ] **Step 2: Run tests to verify they fail**
+
+Run: `pytest tests/test_player_state.py -v`
+Expected: FAIL with `ModuleNotFoundError: No module named 'player.state'`.
+
+- [ ] **Step 3: Write minimal implementation**
+
+```python
+# player/state.py
+"""The player state machine: a stream of Controls -> playback transitions.
+
+Pure decision logic — no mpv, no audio, no serial. Each update() resolves the
+desired Playback (which neutral base clip, how it is altered, what audio plays,
+at what levels) and returns the Transition from the previous Playback. The
+transition KIND encodes design §4.3: the Dark/Light grade and the Left overlay
+are continuous runtime ops (LIVE_UPDATE), whereas swapping the clip or the
+pre-baked Right v2v variant needs a CROSSFADE, and toggling video on/off
+fades to/from black.
+
+Knobs no longer *select* a clip (the base library is neutral by construction);
+they *transform* it. Which neutral base to show is an injected policy
+(`choose_base`), defaulting to the first clip; richer rotation is a later slice.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import Callable, Optional
+
+from hef.selection import Coordinate
+from player.alteration import RenderPlan, plan_alteration
+from player.content import ContentResolution, resolve_content
+from player.controls import Controls
+
+
+class TransitionKind:
+    NONE = "none"
+    LIVE_UPDATE = "live_update"
+    CROSSFADE = "crossfade"
+    FADE_TO_BLACK = "fade_to_black"
+    FADE_FROM_BLACK = "fade_from_black"
+
+
+@dataclass(frozen=True)
+class Playback:
+    """What should currently be playing."""
+
+    clip_id: Optional[str]            # None = black walls
+    plan: Optional[RenderPlan]        # None when black
+    content: ContentResolution
+    volume: int
+    brightness: int
+
+
+@dataclass(frozen=True)
+class Transition:
+    kind: str
+    playback: Playback
+
+
+def _first(library):
+    if not library:
+        raise ValueError("no base clips available to play video")
+    return library[0]
+
+
+_BLACK = Playback(
+    clip_id=None,
+    plan=None,
+    content=ContentResolution("none", False),
+    volume=0,
+    brightness=0,
+)
+
+
+class Player:
+    def __init__(
+        self,
+        base_library,
+        *,
+        choose_base: Callable = _first,
+        approved_only: bool = False,
+    ):
+        self._library = list(base_library)
+        self._choose_base = choose_base
+        self._approved_only = approved_only  # reserved for catalog-backed libs
+        self._current = _BLACK
+
+    def _resolve(self, controls: Controls) -> Playback:
+        content = resolve_content(controls.content)
+        if not content.video:
+            return Playback(
+                clip_id=None,
+                plan=None,
+                content=content,
+                volume=controls.volume,
+                brightness=controls.brightness,
+            )
+        clip = self._choose_base(self._library)
+        coord = Coordinate(controls.left, controls.right, controls.dark, controls.light)
+        return Playback(
+            clip_id=clip.id,
+            plan=plan_alteration(coord),
+            content=content,
+            volume=controls.volume,
+            brightness=controls.brightness,
+        )
+
+    def _classify(self, prev: Playback, nxt: Playback) -> str:
+        prev_video = prev.clip_id is not None
+        next_video = nxt.clip_id is not None
+        if prev == nxt:
+            return TransitionKind.NONE
+        if prev_video and not next_video:
+            return TransitionKind.FADE_TO_BLACK
+        if next_video and not prev_video:
+            return TransitionKind.FADE_FROM_BLACK
+        if next_video and prev_video:
+            if nxt.clip_id != prev.clip_id or nxt.plan.restyle != prev.plan.restyle:
+                return TransitionKind.CROSSFADE
+            return TransitionKind.LIVE_UPDATE
+        # both black: only audio/levels could have changed
+        return TransitionKind.LIVE_UPDATE
+
+    def update(self, controls: Controls) -> Transition:
+        nxt = self._resolve(controls)
+        kind = self._classify(self._current, nxt)
+        self._current = nxt
+        return Transition(kind=kind, playback=nxt)
+```
+
+- [ ] **Step 4: Run tests to verify they pass**
+
+Run: `pytest tests/test_player_state.py -v`
+Expected: PASS.
+
+- [ ] **Step 5: Commit**
+
+```bash
+git add player/state.py tests/test_player_state.py
+git commit -m "feat(player): player state machine — controls stream to transitions"
+```
+
+---
+
+## Task 5: Register the package and run the full suite
+
+**Files:**
+- Modify: `pyproject.toml` (`[tool.setuptools] packages`)
+
+- [ ] **Step 1: Add `"player"` to the packages list**
+
+In `pyproject.toml`, change:
+
+```toml
+[tool.setuptools]
+packages = ["hef", "tools", "simulator"]
+```
+to:
+```toml
+[tool.setuptools]
+packages = ["hef", "tools", "simulator", "player"]
+```
+
+- [ ] **Step 2: Run the entire test suite**
+
+Run: `pytest -q`
+Expected: all prior tests still pass plus the new `test_player_*` files; no failures.
+
+- [ ] **Step 3: Commit**
+
+```bash
+git add pyproject.toml
+git commit -m "build(player): register the player package"
+```
+
+---
+
+## Task 6: Update the roadmap to reflect slice 1 shipped
+
+**Files:**
+- Modify: `docs/ROADMAP.md` (§3 Player Runtime)
+
+- [ ] **Step 1: Update §3 status and deliverables**
+
+Under "## 3. Player Runtime (Pi)", note that the **alteration-engine + player-core slice** (pure logic) is done and tested, link this plan, and list the remaining slices (mpv/ffmpeg runtime integration + GPU grade/overlay shaders; real USB-serial reader + the 3⇄4 framing contract; white-noise DSP; offline v2v variant build pipeline; catalog model changes for audio-source + neutral-base flag). Keep the table's status marker for sub-project 3 as in-progress (⏳), not done.
+
+- [ ] **Step 2: Commit**
+
+```bash
+git add docs/ROADMAP.md
+git commit -m "docs(roadmap): sub-project 3 alteration-engine + player-core slice shipped"
+```
+
+---
+
+## Self-Review
+
+**Spec coverage:**
+- §4.1 per-axis alteration → Task 3 (overlay=Left, restyle=Right, grade=mood). ✓
+- §4.2 composition rule (substrate vs overlay; Left+Right stack) → Task 3 tests `test_left_and_right_stack_not_cancel`, `test_whole_brain_dark_corner_*`. ✓
+- §4.3 runtime vs pre-baked (grade/overlay continuous; restyle variant swap) → Task 4 transition kinds (`LIVE_UPDATE` vs `CROSSFADE`). ✓
+- §5 mood grade, center = identity → Task 3 `test_equal_dark_and_light_is_identity_grade`, signed tone. ✓
+- §6 7-way content dial → Task 2 full table. ✓
+- §7 volume + brightness intensity → Task 1 (modeled) + Task 4 (`test_volume_only_change_is_a_live_update`). ✓
+- Roadmap §3 "done when: plays correct segment, loops, crossfades, goes dark on None, testable with serial mocked" → Task 4 (transitions incl. fade-to-black; serial mocked as a `Controls` stream). Looping is implicit (a clip plays until the desired playback changes); explicit loop timing belongs to the mpv integration slice (deferred, noted in Task 6). ✓ (with the runtime-loop portion deferred and documented).
+
+**Deferred (documented, not gaps):** mpv/ffmpeg + GPU; real serial + framing; white-noise DSP; v2v offline pipeline; catalog audio-source/neutral-base fields; base-clip rotation policy; `approved_only` enforcement against a real catalog (the flag is plumbed but inert here).
+
+**Placeholder scan:** none — every step has concrete code/commands.
+
+**Type consistency:** `Controls(content,left,right,dark,light,volume,brightness)` used identically in Tasks 1 & 4; `RenderPlan.{grade,overlay,restyle}` and `.is_identity` consistent across Tasks 3 & 4; `ContentResolution(audio_source,video)` consistent across Tasks 2 & 4; `TransitionKind` constants consistent. `Coordinate(left,right,dark,light)` matches `hef/selection.py`.

docs/superpowers/specs/2026-06-06-simulator-alteration-preview-design.md

@@ -0,0 +1,242 @@
+# Human Experience Filter — Simulator Alteration Preview (Design)
+
+**Date:** 2026-06-06
+**Status:** Approved design (pre-implementation)
+**Repo:** `human-experience-filter-art`
+**Builds on:** the alteration engine of
+[`2026-06-05-machine-altered-perception-design.md`](./2026-06-05-machine-altered-perception-design.md)
+(the "design" below) and the simulator scaffold of
+[`2026-06-04-experience-simulator-design.md`](./2026-06-04-experience-simulator-design.md).
+**Revises the design:** §4.3 and §10 — the Left analytical HUD is **no longer a
+runtime overlay**; it is **baked into authored variant videos** (see §8 below).
+This is a deliberate trade of near-free multilingual support for authorial
+precision over the HUD.
+**Retires:** the simulator's selection-era "curator's X-ray" view and its
+`/api/select` + `/api/catalog/meta` endpoints (the selection model they
+visualize was superseded by the alteration model).
+
+> **Why this exists.** Operator directive (session 0007): *build and design only
+> things that run in the simulator, and get the whole experience working the way
+> we like in the simulator before moving to hardware.* The slice-1 alteration
+> engine (PR #5) is pure logic with **no simulator surface** — you cannot yet turn
+> the experience knobs and *see* the result. This design brings the alteration
+> into the simulator so the look can be tuned and liked before any Pi/serial work.
+
+---
+
+## 1. Scope
+
+A browser **alteration preview**: turn the four experience knobs and the content
+dial, and see the neutral base footage altered toward the knob state, in real
+time, on a looping clip. The purpose is to **tune the look** of the filter and to
+**settle the knob→strength calibration by eye** (the open §3-vs-§4.2/§5 question
+from session 0006).
+
+**In scope**
+- Live preview of the four experience knobs (Left/Right/Dark/Light) on a looping
+  base clip.
+- **Dark/Light** rendered as a live, deterministic runtime color grade.
+- **Left/Right** rendered by selecting a **pre-baked authored variant clip** from
+  a 5×5 grid and crossfading on change.
+- A **calibration panel** that adjusts the grade curve live; the chosen values are
+  baked back into `player/alteration.py` defaults.
+- A **RenderPlan readout** (the project's "X-ray" honesty): always show the exact
+  numbers the engine produced.
+- The content dial's **video on/off** behavior (so "Off" goes to black), driven by
+  the existing `resolve_content`.
+- Placeholder variant generation so the mechanism is testable before the operator
+  authors real videos.
+
+**Out of scope (this slice)** — real generative v2v; serial input / the 3⇄4
+framing contract; audio playback (music / white-noise / audio-track); the Pi/mpv
+runtime renderer; the full transition/crossfade timing engine; multilingual label
+tables; catalog-model changes. These remain later roadmap slices.
+
+---
+
+## 2. Architecture — Python-canonical, thin browser renderer
+
+`player/alteration.py` stays the **single source of truth** for the alteration
+math (handbook §4.2 — deterministic core, thin I/O). The browser owns only
+*rendering*. Data flow:
+
+```mermaid
+flowchart LR
+  subgraph Browser
+    K[4 experience knobs +<br/>content dial +<br/>calibration sliders]
+    V["&lt;video&gt; variant + canvas grade"]
+    RO[RenderPlan readout]
+  end
+  subgraph FastAPI [simulator/app.py]
+    EP["POST /api/alteration"]
+    CL["GET /api/clips"]
+  end
+  ENG["player.alteration.plan_alteration(coord, calibration)"]
+  K -- "debounced POST {controls, calibration}" --> EP
+  EP --> ENG --> EP -- "RenderPlan {variant, grade}" --> V
+  EP --> RO
+  CL -- "base clip + variant manifest" --> V
+```
+
+- The browser sends control/calibration changes (debounced) and receives a
+  `RenderPlan`. Video filtering itself runs continuously in the browser; only a
+  *plan recompute* makes a round-trip. On localhost these JSON round-trips are
+  imperceptible.
+- "Bake the calibration winner in" = change the `Calibration` defaults in Python.
+  Nothing in the browser is canonical.
+
+---
+
+## 3. The four axes — how each is rendered
+
+| Axis | Engine output | Browser rendering |
+|---|---|---|
+| **Dark / Light** | `ColorGrade.tone` ∈ [−1, 1], center = identity | live color grade on the `<video>`: Light → warm/yellow + negative space toward white; Dark → cool/blue + negative space toward black; 0 = raw. (Confirmed direction in brainstorm.) |
+| **Left / Right** | `VariantRef(left, right)` | select the authored variant clip for `(left, right)`; **crossfade** when it changes; `(0,0)` → raw base. The analytical HUD (Left) and dreamlike restyle (Right) are **baked into the clip** (§8). |
+
+Dark/Light is the only continuously-tunable axis in this slice; Left/Right is a
+discrete selection by coordinate.
+
+---
+
+## 4. The variant grid (per base clip)
+
+Each base clip carries a 5×5 grid keyed by the two baked axes:
+
+- Rows = **Left** (analytical / HUD), 0–4. Columns = **Right** (artistic /
+  dreamlike restyle), 0–4.
+- `(0,0)` = the raw base clip — no authored file needed.
+- The other **24 cells are authored videos** (4 analytical-edge + 4 dreamlike-edge
+  + 16 combined core). This is **per base clip**; authoring load multiplies by the
+  number of base clips (and by language, since the HUD is baked — §8).
+
+The grid is **data**, not code: a manifest the simulator reads (see §6).
+
+---
+
+## 5. Engine reconciliation (`player/alteration.py`)
+
+The slice-1 engine modeled Left/Right as continuous runtime layers
+(`AnalyticalOverlay.intensity`, `Restyle.blend`). Baked variants make that
+obsolete. Changes:
+
+- **`RenderPlan`** becomes `{ grade: ColorGrade, variant: VariantRef }`.
+  - `ColorGrade` — unchanged.
+  - `VariantRef(left, right)` — new; identity selection by coordinate.
+- **Remove** `AnalyticalOverlay` and `Restyle` (their content is now baked into the
+  variant clip) rather than leaving dead fields.
+- **`Calibration`** — a new frozen dataclass parameterizing the grade curve (e.g.
+  `mood_center`, per-axis curve), defaulting to **today's exact behavior**
+  (behavior-preserving). `plan_alteration(coord, calibration=DEFAULT_CALIBRATION)`.
+- **`player/state.py`** — the `CROSSFADE` trigger switches from "restyle changed"
+  to "variant changed"; `LIVE_UPDATE` still covers a grade-only change. Video
+  on/off fades unchanged.
+
+These are framework-code changes that keep the engine pure and unit-tested; they
+do **not** bake any deployment-shape decision into the engine.
+
+---
+
+## 6. Data & endpoints
+
+- **`simulator/clips.py`** (replaces `simulator/fixtures.py`): reads a base-clip +
+  variant manifest. Each base clip: `{ id, title, base_file, license, source,
+  variants: { "L,R": { file, model?, hud_lang? } } }`. Missing cells fall back to
+  the raw base (and are flagged in the readout as "raw / unauthored").
+- **`POST /api/alteration`**: body `{ controls, calibration }` → `RenderPlan`
+  (plus the `ContentResolution` from `resolve_content`, so the dial's video-on/off
+  is honored). The endpoint calls the real `plan_alteration`.
+- **`GET /api/clips`**: the base-clip list + variant manifest for the active base.
+- Video files served as static assets from a sample-media directory.
+- **Removed**: `POST /api/select`, `GET /api/catalog/meta`.
+- `hef.selection` (the library, incl. `Coordinate`) is **untouched**; only the
+  simulator's selection view/endpoints retire. (`ranked_candidates`, added for the
+  old X-ray, may become unused by the simulator — noted, not removed here.)
+
+---
+
+## 7. Calibration tuning
+
+The calibration panel exposes the grade-curve parameters (the two conventions in
+tension: `(2,2,2,2)`-centered vs the `value/4` reading currently implemented, plus
+curve shape). Changing them re-requests the plan and the footage responds live.
+When the operator is happy, the chosen values are written into
+`DEFAULT_CALIBRATION` in `player/alteration.py` and locked in by a unit test.
+
+---
+
+## 8. Baked HUD — the §4.3/§10 revision (accepted trade)
+
+The design's §4.3/§10 kept the Left HUD a **runtime overlay** specifically so the
+v2v substrate is language-agnostic and multilingual support is near-free. This
+design **reverses that for the Left/Right plane**: the operator authors the HUD
+**into** the variant videos to get pixel-precise control over the HUD and the
+analytical↔feeling balance.
+
+**Consequences (accepted):**
+- Multilingual support is **no longer near-free**: baked HUD text means a new
+  language re-renders every label-bearing variant (the §10 "budget landmine").
+  The piece is English-first; broad i18n is deferred/expensive.
+- The live Dark/Light grade is applied **on top** of the baked cell, so it **tints
+  the baked HUD** too (a "Dark" mood cools/darkens the HUD). With baked overlays
+  the grade cannot skip the HUD. Escape hatch: author HUD colors that survive
+  grading, or (future) reinstate a runtime HUD layer.
+
+The parent design's §4.3/§10 must be updated to point at this revision (a task for
+the implementation plan).
+
+---
+
+## 9. Bootstrapping before authored videos exist
+
+The operator will author the 24 variants per base clip; none exist yet. So the
+mechanism is testable immediately, the build includes a **placeholder generator**:
+for at least one base clip, produce the 24 cells by burning the cell's `L,R` (and
+a stub HUD caption) into the base loop via ffmpeg. Real authored clips drop into
+the manifest with **no code change**.
+
+---
+
+## 10. Testing
+
+- **`player/` unit tests:** `DEFAULT_CALIBRATION` is behavior-preserving vs the
+  current helpers; the two calibration conventions produce the expected plans;
+  `VariantRef` selection (incl. `(0,0)` → raw) and the `state.py` crossfade
+  trigger on variant change.
+- **Simulator API tests** (rewrite `tests/test_simulator_api.py`):
+  `POST /api/alteration` returns the engine's plan for given controls/calibration;
+  `GET /api/clips` returns the manifest; the removed endpoints are gone.
+- **No browser/E2E automation** this slice (manual visual tuning is the point);
+  the rendering JS is kept thin and the engine logic stays in tested Python.
+
+---
+
+## 11. What ships
+
+- `player/alteration.py` (parameterized `Calibration`, `VariantRef`, slimmed
+  `RenderPlan`) + `player/state.py` crossfade-trigger update.
+- `simulator/clips.py` (variant manifest) replacing `fixtures.py`.
+- `simulator/app.py` new endpoints; selection endpoints removed.
+- `simulator/static/` rewritten as the Player preview (variant `<video>` +
+  crossfade, live grade, calibration panel, RenderPlan readout, content dial).
+- Placeholder-variant generator + a sample base clip.
+- Tests above; `docs/USER_GUIDE.md` "Playing with the simulator" rewritten;
+  parent design §4.3/§10 pointer updated; `docs/ROADMAP.md` §3 updated.
+
+---
+
+## 12. Open questions (for the plan, not blockers)
+
+- **Grade vs baked HUD interaction** — accepted that the grade tints the HUD;
+  revisit only if it reads badly once real authored clips exist.
+- **Sample base clip** — pick one CC0 nature loop for the placeholder grid.
+- **Crossfade timing in the browser** — a simple opacity crossfade is enough for
+  tuning; the real timing engine is a later slice.
+
+---
+
+## 13. Out of scope (YAGNI)
+
+Real generative v2v; serial / firmware; audio playback; the Pi renderer; the full
+transition engine; multilingual tables; catalog-model changes; retiring
+`hef.selection.ranked_candidates`. All remain later roadmap work.

player/alteration.py

@@ -0,0 +1,98 @@
+"""The alteration engine: a knob vector -> a layered RenderPlan (design §4, §5).
+
+Replaces the 2026-06-04 nearest-match *selection* with a *transformation* of a
+neutral base clip. Given the four experience knobs, it produces three layers
+that compose per §4.2:
+
+  - Substrate transforms (alter pixels, blend with each other):
+      * Restyle  -- the Right axis: a pre-baked generative v2v dreamlike restyle.
+      * ColorGrade -- the mood axis (Dark/Light): a deterministic color grade.
+  - Overlay (composited on top of the substrate):
+      * AnalyticalOverlay -- the Left axis: HUD/labels/measurement.
+
+Left and Right are NOT opposites; they live on different layers and stack
+(§4.2). Dark and Light are the two poles of one mood grade whose center is the
+identity (§5).
+
+Calibration note: the knob->strength curves below are the single source of
+truth for how a 0..4 position maps to a transform strength. See the session
+0006 transcript Deferred decisions for the §3-vs-§4.2/§5 reconciliation.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+from hef.selection import Coordinate
+
+KNOB_MAX = 4  # knob full-scale (0..4)
+
+
+@dataclass(frozen=True)
+class ColorGrade:
+    """Mood-axis grade (§5). `tone` is signed: >0 warm yellow->white (light),
+    <0 cool blue->black (dark), 0 = identity (raw, ungraded)."""
+
+    tone: float
+
+    @property
+    def is_identity(self) -> bool:
+        return self.tone == 0.0
+
+
+@dataclass(frozen=True)
+class AnalyticalOverlay:
+    """Left axis (§4.1): analytical HUD/annotation/labels, composited on top.
+    `intensity` 0..1 (0 = no overlay)."""
+
+    intensity: float
+
+
+@dataclass(frozen=True)
+class Restyle:
+    """Right axis (§4.1): pre-baked generative v2v dreamlike substrate.
+    `blend` 0..1 (0 = raw substrate, no restyle)."""
+
+    blend: float
+
+
+@dataclass(frozen=True)
+class RenderPlan:
+    """The full layered alteration for one knob vector (§4.2)."""
+
+    grade: ColorGrade
+    overlay: AnalyticalOverlay
+    restyle: Restyle
+
+    @property
+    def is_identity(self) -> bool:
+        """True when the plan leaves the neutral base un-altered."""
+        return (
+            self.grade.is_identity
+            and self.overlay.intensity == 0.0
+            and self.restyle.blend == 0.0
+        )
+
+
+def _overlay_intensity(left: int) -> float:
+    """Left knob -> analytical-overlay intensity (0..1)."""
+    return left / KNOB_MAX
+
+
+def _restyle_blend(right: int) -> float:
+    """Right knob -> v2v restyle blend (0..1)."""
+    return right / KNOB_MAX
+
+
+def _mood_tone(dark: int, light: int) -> float:
+    """(dark, light) -> signed mood grade in [-1, 1]; equal -> 0 identity (§5)."""
+    return (light - dark) / KNOB_MAX
+
+
+def plan_alteration(coord: Coordinate) -> RenderPlan:
+    """Map a knob vector to its layered RenderPlan (design §4)."""
+    return RenderPlan(
+        grade=ColorGrade(tone=_mood_tone(coord.dark, coord.light)),
+        overlay=AnalyticalOverlay(intensity=_overlay_intensity(coord.left)),
+        restyle=Restyle(blend=_restyle_blend(coord.right)),
+    )

player/content.py

@@ -0,0 +1,42 @@
+"""Resolve the 7-way content dial into an audio source + video on/off (§6).
+
+The single source of truth for design §6's table: which audio source plays and
+whether the projector shows video, for each dial position.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+# The four distinct audio sources. "white_noise" is generated at runtime;
+# "music" is the public-domain classical pool; "audio_track" is the clip's own
+# field audio; "none" is silence.
+AUDIO_SOURCES = frozenset({"none", "white_noise", "music", "audio_track"})
+
+
+@dataclass(frozen=True)
+class ContentResolution:
+    audio_source: str
+    video: bool
+
+
+# Design §6, one row per dial position.
+_TABLE = {
+    "off": ContentResolution("none", False),
+    "white_noise": ContentResolution("white_noise", False),
+    "music": ContentResolution("music", False),
+    "audio_track": ContentResolution("audio_track", False),
+    "video": ContentResolution("none", True),
+    "music_video": ContentResolution("music", True),
+    "audio_video": ContentResolution("audio_track", True),
+}
+
+
+def resolve_content(position: str) -> ContentResolution:
+    """Map a content-dial position to its audio source and video flag (§6)."""
+    try:
+        return _TABLE[position]
+    except KeyError:
+        raise ValueError(
+            f"unknown content position {position!r}; expected one of {sorted(_TABLE)}"
+        ) from None

player/controls.py

@@ -0,0 +1,68 @@
+"""Control-panel state: the data shape read from the Arduino over serial.
+
+This is the serial-contract payload shared with sub-project 4 (firmware). It
+models the full panel from design §6/§7: the 7-way content dial, the four
+experience knobs (0..4), and the two intensity levels (volume, brightness).
+The wire framing itself is the separate 3<->4 serial contract; this module is
+the *decoded* form.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass, fields
+
+# The seven positions of the content dial (design §6).
+CONTENT_POSITIONS = frozenset(
+    {"off", "white_noise", "music", "audio_track", "video", "music_video", "audio_video"}
+)
+
+KNOB_FIELDS = ("left", "right", "dark", "light", "volume", "brightness")
+KNOB_MIN = 0
+KNOB_MAX = 4
+
+
+class ControlsError(ValueError):
+    """Raised when a Controls payload is structurally invalid."""
+
+
+@dataclass(frozen=True)
+class Controls:
+    content: str
+    left: int
+    right: int
+    dark: int
+    light: int
+    volume: int
+    brightness: int
+
+
+def validate_controls(c: Controls) -> None:
+    """Raise ControlsError if the payload is structurally invalid."""
+    if c.content not in CONTENT_POSITIONS:
+        raise ControlsError(
+            f"invalid content position {c.content!r}; "
+            f"expected one of {sorted(CONTENT_POSITIONS)}"
+        )
+    for name in KNOB_FIELDS:
+        value = getattr(c, name)
+        if isinstance(value, bool) or not isinstance(value, int):
+            raise ControlsError(f"knob {name} must be an int, got {value!r}")
+        if not (KNOB_MIN <= value <= KNOB_MAX):
+            raise ControlsError(
+                f"knob {name}={value} out of range {KNOB_MIN}..{KNOB_MAX}"
+            )
+
+
+def parse_controls(data: dict) -> Controls:
+    """Build a validated Controls from a decoded mapping, rejecting unknown or
+    missing keys."""
+    known = {f.name for f in fields(Controls)}
+    unknown = set(data) - known
+    if unknown:
+        raise ControlsError(f"unknown keys: {sorted(unknown)}")
+    missing = known - set(data)
+    if missing:
+        raise ControlsError(f"missing keys: {sorted(missing)}")
+    c = Controls(**data)
+    validate_controls(c)
+    return c

player/state.py

@@ -0,0 +1,120 @@
+"""The player state machine: a stream of Controls -> playback transitions.
+
+Pure decision logic — no mpv, no audio, no serial. Each update() resolves the
+desired Playback (which neutral base clip, how it is altered, what audio plays,
+at what levels) and returns the Transition from the previous Playback. The
+transition KIND encodes design §4.3: the Dark/Light grade and the Left overlay
+are continuous runtime ops (LIVE_UPDATE), whereas swapping the clip or the
+pre-baked Right v2v variant needs a CROSSFADE, and toggling video on/off
+fades to/from black.
+
+Knobs no longer *select* a clip (the base library is neutral by construction);
+they *transform* it. Which neutral base to show is an injected policy
+(`choose_base`), defaulting to the first clip; richer rotation is a later slice.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import Callable, Optional
+
+from hef.selection import Coordinate
+from player.alteration import RenderPlan, plan_alteration
+from player.content import ContentResolution, resolve_content
+from player.controls import Controls
+
+
+class TransitionKind:
+    NONE = "none"
+    LIVE_UPDATE = "live_update"
+    CROSSFADE = "crossfade"
+    FADE_TO_BLACK = "fade_to_black"
+    FADE_FROM_BLACK = "fade_from_black"
+
+
+@dataclass(frozen=True)
+class Playback:
+    """What should currently be playing."""
+
+    clip_id: Optional[str]            # None = black walls
+    plan: Optional[RenderPlan]        # None when black
+    content: ContentResolution
+    volume: int
+    brightness: int
+
+
+@dataclass(frozen=True)
+class Transition:
+    kind: str
+    playback: Playback
+
+
+def _first(library):
+    if not library:
+        raise ValueError("no base clips available to play video")
+    return library[0]
+
+
+_BLACK = Playback(
+    clip_id=None,
+    plan=None,
+    content=ContentResolution("none", False),
+    volume=0,
+    brightness=0,
+)
+
+
+class Player:
+    def __init__(
+        self,
+        base_library,
+        *,
+        choose_base: Callable = _first,
+        approved_only: bool = False,
+    ):
+        self._library = list(base_library)
+        self._choose_base = choose_base
+        self._approved_only = approved_only  # reserved for catalog-backed libs
+        self._current = _BLACK
+
+    def _resolve(self, controls: Controls) -> Playback:
+        content = resolve_content(controls.content)
+        if not content.video:
+            return Playback(
+                clip_id=None,
+                plan=None,
+                content=content,
+                volume=controls.volume,
+                brightness=controls.brightness,
+            )
+        clip = self._choose_base(self._library)
+        coord = Coordinate(controls.left, controls.right, controls.dark, controls.light)
+        return Playback(
+            clip_id=clip.id,
+            plan=plan_alteration(coord),
+            content=content,
+            volume=controls.volume,
+            brightness=controls.brightness,
+        )
+
+    def _classify(self, prev: Playback, nxt: Playback) -> str:
+        prev_video = prev.clip_id is not None
+        next_video = nxt.clip_id is not None
+        if prev == nxt:
+            return TransitionKind.NONE
+        if prev_video and not next_video:
+            return TransitionKind.FADE_TO_BLACK
+        if next_video and not prev_video:
+            return TransitionKind.FADE_FROM_BLACK
+        if next_video and prev_video:
+            if nxt.clip_id != prev.clip_id or nxt.plan.restyle != prev.plan.restyle:
+                return TransitionKind.CROSSFADE
+            return TransitionKind.LIVE_UPDATE
+        # both black: only audio/levels could have changed
+        return TransitionKind.LIVE_UPDATE
+
+    def update(self, controls: Controls) -> Transition:
+        nxt = self._resolve(controls)
+        kind = self._classify(self._current, nxt)
+        self._current = nxt
+        return Transition(kind=kind, playback=nxt)

pyproject.toml

@@ -12,7 +12,7 @@ requires = ["setuptools>=68"]
 build-backend = "setuptools.build_meta"
 
 [tool.setuptools]
-packages = ["hef", "tools", "simulator"]
+packages = ["hef", "tools", "simulator", "player"]
 
 [project.scripts]
 hef-ingest = "tools.ingest_cli:main"

sessions/0006/SESSION-0006.0-TRANSCRIPT-2026-06-05T17-52--2026-06-05T18-15.md

@@ -0,0 +1,134 @@
+# Session 0006.0 — Transcript
+
+> App: human-experience-filter-art
+> Type: coding
+> Start: 2026-06-05T17-52 (PST) · End: 2026-06-05T18-15 (PST)
+> Goal: `/goal next` — drive the roadmap to its next frontier item (sub-project 3,
+>       the player / machine-alteration engine), and build it.
+> Outcome: **Sub-project 3 slice 1 — the pure-logic alteration-engine + player
+>          core — built and MERGED to `main` via PR #5** (merge commit `aeeed66`).
+>          New `player/` package; 56 new tests (189 passed / 2 skipped total).
+>          Sub-project 3 advanced from "next" to "in progress."
+
+## Plan
+
+Begin sub-project 3 (Player Runtime + alteration engine) per `docs/ROADMAP.md` §3
+and the approved machine-altered-perception design (§4 alteration engine, §5 mood
+grade, §6 7-way content dial, §7 intensity). Sub-project 3 is large (runtime
+grading + overlay compositing + v2v variant selection + serial input + mpv/GPU +
+white-noise DSP); this session ships **slice 1 — the pure-logic core** as a new
+`player/` package, fully unit-tested with all I/O behind injected interfaces,
+mirroring how sub-project 1 was the pure-logic dependency root. Process:
+writing-plans → TDD → branch → PR → merge.
+
+## Launch prompt
+
+```
+/goal next — drive the roadmap to its next frontier item.
+
+Per project memory (session 0005, machine-altered-perception design SPEC merged
+to main via PR #4), the roadmap frontier is sub-project 3: the player /
+machine-alteration engine. This coding session builds that.
+```
+
+## Pre-session state
+
+- `main` @ `77746e4` locally (behind `origin/main` by 2 — session 0005's finalized
+  transcript + this session's claim placeholder); fast-forwarded to `origin/main`
+  during init.
+- Sub-projects 1 & 2 done/merged; design of record = the machine-altered-perception
+  revision (PR #4). No `player/` package and no sub-project-3 plan existed yet.
+- Launch cwd was the stale, already-merged worktree
+  `.worktrees/feature-BuildSimulator11/` (branch `feature/machine-altered-perception-spec`,
+  remote gone) — same situation as session 0005.
+
+## Turn-by-turn arc
+
+1. **Gate / classify.** `/goal next` → unambiguously a coding session (roadmap
+   frontier = sub-project 3 build). Ran `wgl-session-coding-init`.
+2. **Claim snag (same as 0005, kept in the record).** `resolve-app.py` reported
+   **ambiguous** — the nested worktree's `app.json` discovered alongside the main
+   clone's. Read the resolver to confirm root cause (`find_app_jsons` prunes
+   `.git/node_modules/…` but not `.worktrees/`). Worked around with
+   `WGL_APP_SCAN_DEPTH=4` (prunes the depth-5 worktree copy, keeps the depth-3 main
+   one). Claimed session **0006**, type coding, at `e694489`. Filed a plugin-feedback
+   note for the recurring gap (`feedback/2026-06-05T18-13-resolver-nested-worktree-ambiguous.md`).
+3. **Baseline + branch.** Fast-forwarded the main clone; confirmed PR #4 merged;
+   created `feature/player-alteration-core` off `origin/main` in the worktree.
+4. **Read the design.** Read ROADMAP §3 + the machine-altered-perception spec
+   (§4 alteration engine, §5 mood grade, §6 7-way dial, §7 intensity), and the
+   existing `hef/` conventions (frozen dataclasses, pure modules, heavy unit tests).
+5. **Scoped the session → slice 1.** Sub-project 3 is too large for one session;
+   chose the pure-logic core (controls model, content-dial resolver, alteration
+   render-plan, player state machine) with all I/O behind injected interfaces, and
+   deferred the renderer/serial/white-noise/v2v/catalog slices (named in the plan).
+6. **Surfaced a spec ambiguity (Deferred decision).** §3 "(2,2,2,2) neutral" vs
+   §4.2 (Left/Right stack as independent layers) vs §5 (mood center = identity)
+   cannot all be literally true for four independent knobs. Resolved with a
+   swappable calibration: brain `value/4`, mood `(light−dark)/4`; flagged for
+   operator confirm.
+7. **writing-plans.** Wrote `docs/superpowers/plans/2026-06-05-player-alteration-core.md`
+   (6 TDD tasks, full code + tests, self-review against the spec).
+8. **TDD implementation.** Red→green→commit per module: `player/controls.py`
+   (Controls, validation, parse), `player/content.py` (§6 7-way table),
+   `player/alteration.py` (RenderPlan: ColorGrade/AnalyticalOverlay/Restyle +
+   calibration helpers), `player/state.py` (Player state machine + Transition
+   kinds). Registered the package in `pyproject.toml`; updated ROADMAP §3.
+9. **Verify.** Full suite green: **189 passed, 2 skipped** (the opt-in ffprobe
+   tests), 56 of them new player tests. No regressions.
+10. **Ship.** Pushed the branch; created **PR #5** and merged it via the Gitea API
+    helper (merge commit `aeeed66`); synced the main clone; deleted the remote
+    feature branch.
+11. **Wrap.** Filed plugin feedback, updated memory, finalized.
+
+## Cut state
+
+- `main` @ `aeeed66` (PR #5 merged). `player/` package present: `controls.py`,
+  `content.py`, `alteration.py`, `state.py` + 4 test files. Full suite 189 passed /
+  2 skipped.
+- Sub-project 3 = **⏳ in progress**. Slice 1 done; remaining slices listed in
+  ROADMAP §3 and `[[sub-project-3-player-progress]]`.
+- Working tree clean. Remote feature branch deleted; the local worktree remains on
+  the now-merged `feature/player-alteration-core` branch (harmless).
+
+## Deferred decisions (operator plate)
+
+Two low-confidence calls made autonomously this session — both flagged for operator
+confirmation:
+
+1. **Knob→strength calibration (§3 vs §4.2/§5 conflict).** §3 says "(2,2,2,2) is
+   neutral," but §4.2 (Left/Right stack as independent layers: overlay vs substrate)
+   and §5 (mood center = identity) conflict with that for four independent physical
+   knobs. Implemented: brain knobs `strength = value/4` (0 = off, 4 = max — full
+   range, honors §4.2 stacking), mood `tone = (light − dark)/4` (equal dark/light →
+   identity, honors §5). Under this the un-altered base is `(0,0,·,·)` with
+   `dark==light`, **not** `(2,2,2,2)` — read as a vestige of the old coordinate-grid
+   *center*. The calibration is three one-line helpers in `player/alteration.py`;
+   flipping to a "centered at 2 = no push" convention is a localized change that
+   leaves the RenderPlan shape and all downstream logic untouched. **Recommend
+   operator confirm the intended panel UX.**
+2. **Volume/Brightness granularity.** Modeled as `0..4` ints for uniformity with the
+   experience knobs and the Arduino's `0..4` quantization (roadmap §4). The spec
+   calls them "levels" without fixing granularity; revisit if the panel warrants
+   finer steps.
+
+## Next-session prompt
+
+The roadmap frontier is now the remaining sub-project-3 slices. Read
+`[[sub-project-3-player-progress]]` and the slice-1 plan first. Two strong
+candidates for the next slice — the **runtime renderer** (makes the core visible)
+or the **serial framing contract + input adapter** (unblocks sub-project 4 in
+parallel):
+
+```
+/goal Sub-project 3 slice 2 — settle the 3⇄4 serial framing contract and build the
+USB-serial / keyboard input adapter that feeds the player a `Controls` stream
+(unblocks sub-project 4), per docs/ROADMAP.md §3 and docs/superpowers/plans/2026-06-05-player-alteration-core.md.
+Alternatively start the runtime renderer (mpv/ffmpeg + grade/overlay). First
+confirm the open knob→strength calibration decision (§3 vs §4.2/§5).
+```
+
+Gotcha to carry forward: running from the nested `.worktrees/…` checkout breaks
+`resolve-app.py` (ambiguous app.json) — run from the main clone, or use
+`WGL_APP_SCAN_DEPTH=4` on claim and explicit `--sessions-*` flags on publish, until
+the plugin fix lands.

sessions/0006/SESSION-0006.0-TRANSCRIPT-2026-06-05T17-52--INPROGRESS.md

@@ -1,27 +0,0 @@
-# Session 0006.0 — Transcript
-
-> App: human-experience-filter-art
-> Start: 2026-06-05T17-52 (PST)
-> Type: coding
-> Status: **PLACEHOLDER — claimed at session start; finalized at session end.**
->
-> This file reserves session ID 0006 for human-experience-filter-art. The driver replaces this
-> body with the full transcript and renames the file to its final
-> SESSION-0006.0-TRANSCRIPT-2026-06-05T17-52--<end>.md form at session end.
-
-## Launch prompt
-
-```
-/goal next — drive the roadmap to its next frontier item.
-
-Per project memory (session 0005, machine-altered-perception design SPEC merged
-to main via PR #4), the roadmap frontier is sub-project 3: the player /
-machine-alteration engine. This coding session builds that.
-
-```
-
-## Deferred decisions
-
-_Autonomous-mode low-confidence calls the driver made and would have
-liked operator input on. Appended as the session runs; surfaced at
-finalize. Empty if none._

tests/test_player_alteration.py

@@ -0,0 +1,80 @@
+import pytest
+
+from hef.selection import Coordinate
+from player.alteration import (
+    AnalyticalOverlay,
+    ColorGrade,
+    RenderPlan,
+    Restyle,
+    plan_alteration,
+)
+
+
+def _coord(left=0, right=0, dark=0, light=0):
+    return Coordinate(left=left, right=right, dark=dark, light=light)
+
+
+def test_all_zero_knobs_is_the_unaltered_base():
+    plan = plan_alteration(_coord())
+    assert plan.is_identity
+    assert plan.overlay.intensity == 0.0
+    assert plan.restyle.blend == 0.0
+    assert plan.grade.tone == 0.0
+    assert plan.grade.is_identity
+
+
+def test_left_drives_the_analytical_overlay_only():
+    plan = plan_alteration(_coord(left=4))
+    assert plan.overlay.intensity == 1.0
+    assert plan.restyle.blend == 0.0  # Left does not touch the substrate
+    assert plan.grade.tone == 0.0
+
+
+def test_right_drives_the_restyle_substrate_only():
+    plan = plan_alteration(_coord(right=2))
+    assert plan.restyle.blend == 0.5
+    assert plan.overlay.intensity == 0.0  # Right does not add overlay
+
+
+def test_left_and_right_stack_not_cancel():
+    # design §4.2: whole-brain corner = dreamlike substrate WITH labels on top
+    plan = plan_alteration(_coord(left=4, right=4))
+    assert plan.overlay.intensity == 1.0
+    assert plan.restyle.blend == 1.0
+
+
+def test_light_pole_grades_warm_positive_tone():
+    plan = plan_alteration(_coord(light=4))
+    assert plan.grade.tone == 1.0
+    assert not plan.grade.is_identity
+
+
+def test_dark_pole_grades_cool_negative_tone():
+    plan = plan_alteration(_coord(dark=4))
+    assert plan.grade.tone == -1.0
+
+
+def test_equal_dark_and_light_is_identity_grade():
+    # design §5: the mood center is the raw, ungraded footage
+    assert plan_alteration(_coord(dark=3, light=3)).grade.is_identity
+    assert plan_alteration(_coord(dark=2, light=2)).grade.is_identity
+
+
+def test_dark_minus_light_sets_intermediate_tone():
+    assert plan_alteration(_coord(dark=4, light=2)).grade.tone == pytest.approx(-0.5)
+    assert plan_alteration(_coord(dark=1, light=3)).grade.tone == pytest.approx(0.5)
+
+
+def test_whole_brain_dark_corner_stacks_grade_substrate_and_overlay():
+    # design §4.2 "Dark + analytical": cold measurement over a melancholy scene
+    plan = plan_alteration(_coord(left=4, right=2, dark=4, light=0))
+    assert plan.overlay.intensity == 1.0
+    assert plan.restyle.blend == 0.5
+    assert plan.grade.tone == -1.0
+    assert not plan.is_identity
+
+
+def test_render_plan_is_frozen():
+    plan = plan_alteration(_coord())
+    with pytest.raises(Exception):
+        plan.grade.tone = 0.5  # type: ignore[misc]

tests/test_player_content.py

@@ -0,0 +1,34 @@
+import pytest
+
+from player.content import AUDIO_SOURCES, ContentResolution, resolve_content
+
+
+def test_audio_sources_are_the_four_distinct_sources():
+    assert AUDIO_SOURCES == frozenset({"none", "white_noise", "music", "audio_track"})
+
+
+# The §6 table, row by row: position -> (audio_source, video).
+@pytest.mark.parametrize(
+    "position,audio_source,video",
+    [
+        ("off", "none", False),
+        ("white_noise", "white_noise", False),
+        ("music", "music", False),
+        ("audio_track", "audio_track", False),
+        ("video", "none", True),
+        ("music_video", "music", True),
+        ("audio_video", "audio_track", True),
+    ],
+)
+def test_resolve_content_matches_spec_table(position, audio_source, video):
+    assert resolve_content(position) == ContentResolution(audio_source=audio_source, video=video)
+
+
+def test_off_is_void_state_black_and_silent():
+    r = resolve_content("off")
+    assert r.video is False and r.audio_source == "none"
+
+
+def test_resolve_content_rejects_unknown_position():
+    with pytest.raises(ValueError):
+        resolve_content("bogus")

tests/test_player_controls.py

@@ -0,0 +1,53 @@
+import pytest
+
+from player.controls import (
+    Controls,
+    CONTENT_POSITIONS,
+    ControlsError,
+    validate_controls,
+    parse_controls,
+)
+
+
+def test_content_positions_are_the_seven_from_the_spec():
+    assert CONTENT_POSITIONS == frozenset(
+        {"off", "white_noise", "music", "audio_track", "video", "music_video", "audio_video"}
+    )
+
+
+def test_valid_controls_pass_validation():
+    c = Controls(content="video", left=0, right=4, dark=2, light=2, volume=3, brightness=4)
+    validate_controls(c)  # does not raise
+
+
+def test_invalid_content_position_rejected():
+    c = Controls(content="bogus", left=0, right=0, dark=0, light=0, volume=0, brightness=0)
+    with pytest.raises(ControlsError):
+        validate_controls(c)
+
+
+@pytest.mark.parametrize("field", ["left", "right", "dark", "light", "volume", "brightness"])
+@pytest.mark.parametrize("bad", [-1, 5, True])
+def test_out_of_range_or_non_int_knob_rejected(field, bad):
+    kwargs = dict(content="off", left=0, right=0, dark=0, light=0, volume=0, brightness=0)
+    kwargs[field] = bad
+    with pytest.raises(ControlsError):
+        validate_controls(Controls(**kwargs))
+
+
+def test_parse_controls_from_mapping():
+    c = parse_controls(
+        {"content": "music_video", "left": 1, "right": 2, "dark": 3, "light": 0, "volume": 2, "brightness": 1}
+    )
+    assert c == Controls("music_video", 1, 2, 3, 0, 2, 1)
+
+
+def test_parse_controls_rejects_unknown_keys():
+    with pytest.raises(ControlsError):
+        parse_controls({"content": "off", "left": 0, "right": 0, "dark": 0,
+                        "light": 0, "volume": 0, "brightness": 0, "bogus": 1})
+
+
+def test_parse_controls_rejects_missing_keys():
+    with pytest.raises(ControlsError):
+        parse_controls({"content": "off", "left": 0})

tests/test_player_state.py

@@ -0,0 +1,112 @@
+from dataclasses import dataclass
+
+import pytest
+
+from player.controls import Controls
+from player.state import Player, Playback, Transition, TransitionKind
+
+
+@dataclass(frozen=True)
+class FakeClip:
+    id: str
+
+
+LIB = [FakeClip("base-a"), FakeClip("base-b")]
+
+
+def _controls(content="video", left=0, right=0, dark=0, light=0, volume=2, brightness=2):
+    return Controls(content, left, right, dark, light, volume, brightness)
+
+
+def test_first_update_to_video_fades_in_from_black():
+    p = Player(LIB)
+    t = p.update(_controls(content="video"))
+    assert t.kind == TransitionKind.FADE_FROM_BLACK
+    assert t.playback.clip_id == "base-a"
+    assert t.playback.content.video is True
+
+
+def test_off_from_video_fades_to_black_and_silences():
+    p = Player(LIB)
+    p.update(_controls(content="video"))
+    t = p.update(_controls(content="off"))
+    assert t.kind == TransitionKind.FADE_TO_BLACK
+    assert t.playback.clip_id is None
+    assert t.playback.content.audio_source == "none"
+
+
+def test_no_change_yields_none_transition():
+    p = Player(LIB)
+    p.update(_controls(content="video", left=1))
+    t = p.update(_controls(content="video", left=1))
+    assert t.kind == TransitionKind.NONE
+
+
+def test_grade_change_is_a_live_update_not_a_crossfade():
+    # design §4.3: the Dark/Light grade is a continuous runtime op
+    p = Player(LIB)
+    p.update(_controls(content="video", dark=0, light=0))
+    t = p.update(_controls(content="video", dark=4, light=0))
+    assert t.kind == TransitionKind.LIVE_UPDATE
+    assert t.playback.plan.grade.tone == -1.0
+
+
+def test_overlay_change_is_a_live_update():
+    p = Player(LIB)
+    p.update(_controls(content="video", left=0))
+    t = p.update(_controls(content="video", left=4))
+    assert t.kind == TransitionKind.LIVE_UPDATE
+    assert t.playback.plan.overlay.intensity == 1.0
+
+
+def test_restyle_change_crossfades_the_substrate():
+    # design §4.3: the Right v2v substrate is a pre-baked variant swap
+    p = Player(LIB)
+    p.update(_controls(content="video", right=0))
+    t = p.update(_controls(content="video", right=4))
+    assert t.kind == TransitionKind.CROSSFADE
+    assert t.playback.plan.restyle.blend == 1.0
+
+
+def test_volume_only_change_is_a_live_update():
+    p = Player(LIB)
+    p.update(_controls(content="video", volume=1))
+    t = p.update(_controls(content="video", volume=4))
+    assert t.kind == TransitionKind.LIVE_UPDATE
+    assert t.playback.volume == 4
+
+
+def test_audio_source_change_while_black_is_a_live_update():
+    p = Player(LIB)
+    p.update(_controls(content="white_noise"))
+    t = p.update(_controls(content="music"))
+    assert t.kind == TransitionKind.LIVE_UPDATE
+    assert t.playback.content.audio_source == "music"
+
+
+def test_injected_base_chooser_is_used():
+    p = Player(LIB, choose_base=lambda lib: lib[1])
+    t = p.update(_controls(content="video"))
+    assert t.playback.clip_id == "base-b"
+
+
+def test_empty_library_with_video_raises():
+    p = Player([])
+    with pytest.raises(ValueError):
+        p.update(_controls(content="video"))
+
+
+def test_off_with_empty_library_is_fine():
+    p = Player([])
+    # levels at 0 match the initial black state, so this is a no-op transition
+    t = p.update(_controls(content="off", volume=0, brightness=0))
+    assert t.kind == TransitionKind.NONE  # already black at init
+    assert t.playback.clip_id is None
+
+
+def test_off_with_levels_from_black_is_a_live_update():
+    p = Player([])
+    t = p.update(_controls(content="off", volume=3, brightness=2))
+    assert t.kind == TransitionKind.LIVE_UPDATE  # black->black, levels set
+    assert t.playback.clip_id is None
+    assert t.playback.volume == 3