From 604d1eeae39fc14ea27941d137390ef75e04e6a6 Mon Sep 17 00:00:00 2001
From: Cameron <cameron@pfiffer.org>
Date: Fri, 10 Jul 2026 21:55:57 -0700
Subject: [PATCH] Add canvas-wheel camera zoom
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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Give the Bevy canvas a direct mouse and trackpad zoom path while preserving independent right-rail scrolling and shared framing across both render modes.

Defense: wiki/interface/bevy-digital-real-canvas.md#camera-and-depth-contract keeps camera movement frontend-only and anchored to the shared canvas.

👾 Generated with [Letta Code](https://letta.com)

Co-Authored-By: Letta Code <noreply@letta.com>
---
 README.md                                  |   4 +-
 crates/misaligned-bevy/src/main.rs         | 122 ++++++++++++++++++---
 wiki/interface/action-vocabulary.md        |   2 +-
 wiki/interface/bevy-digital-real-canvas.md |   5 +
 wiki/interface/bevy.md                     |  22 ++--
 wiki/log/2026-07-10-bevy-canvas-zoom.md    |  31 ++++++
 wiki/log/DEVLOG.md                         |   5 +
 7 files changed, 161 insertions(+), 30 deletions(-)
 create mode 100644 wiki/log/2026-07-10-bevy-canvas-zoom.md

diff --git a/README.md b/README.md
index 260d37c9..c757a405 100644
--- a/README.md
+++ b/README.md
@@ -139,8 +139,8 @@ retired words are inventoried in
 | `Esc` | Clear selection (or close menu / dial when open) |
 | In menu: `j`/`k` or numbers, `Enter`, `ESC` | Select a row / execute it / close the menu |
 | `;` | Focus the most recent anchored (`»`) log event — cursor jumps there, menu opens; repeat to walk older ones (terminal; in Bevy click a `>` trace row) |
-| `[` / `]` | Zoom (Bevy) |
-| Mouse wheel over right pane / `PageUp` / `PageDown` / `Home` / `End` | Scroll Bevy sidebar |
+| `[` / `]` or mouse/trackpad wheel over the canvas | Zoom in / out (Bevy) |
+| Mouse/trackpad wheel over right pane / `PageUp` / `PageDown` / `Home` / `End` | Scroll Bevy sidebar |
 | `F3` | Flip Bevy render: material (HD-2D, default) / flat sensorium |
 | `F4` | Dev work light: flood the material render flat and neutral (inspection only) |
 | `Ctrl+S` / `Ctrl+L` | Save / load |
diff --git a/crates/misaligned-bevy/src/main.rs b/crates/misaligned-bevy/src/main.rs
index 40455f0d..c63d77e6 100644
--- a/crates/misaligned-bevy/src/main.rs
+++ b/crates/misaligned-bevy/src/main.rs
@@ -82,8 +82,14 @@ const CLOSE_DIST: f32 = 2.6;
 /// Zoom multipliers around the close default (material-dark-frame.md
 /// criterion 5): min stays a tight rack close-up, max can still survey
 /// lit pools without the plan driving the frame. [TUNE].
+const ZOOM_STEP: f32 = 0.8;
 const MIN_ZOOM: f32 = 0.5;
 const MAX_ZOOM: f32 = 6.0;
+const MIN_FLAT_ZOOM: f32 = 0.25;
+const MAX_FLAT_ZOOM: f32 = 1.5;
+/// A pixel-scrolling trackpad needs a travel distance rather than treating
+/// every sub-pixel update as a full discrete wheel notch. [TUNE].
+const WHEEL_PIXELS_PER_ZOOM_STEP: f32 = 120.0;
 /// The dark rig's near-nothing ambient brightness (material-dark-frame.md:
 /// a physically dark room before Eyes — nobody is home, the AI does not need
 /// lights). A live sight feed replaces this with camera exposure. [TUNE].
@@ -3578,10 +3584,14 @@ const WAKE_LEN: f32 = 6.2;
 /// rest is dark). Fit-to-known-content is retired as this camera's framing
 /// driver: the known extent is a plan fact, and the plan no longer drives
 /// the camera (that fit-to-content default now governs the flat sensorium
-/// only). Zoomable with [ ]. The wake sequence hands off to this frame.
+/// only). Zoomable with [ ] or the canvas wheel. The wake sequence hands off
+/// to this frame.
+#[allow(clippy::too_many_arguments)] // ECS camera/input resources are distinct.
 fn update_camera_real(
     time: Res<Time>,
     kb: Res<ButtonInput<KeyCode>>,
+    mut mouse_wheel: MessageReader<MouseWheel>,
+    windows: Query<&Window, With<PrimaryWindow>>,
     game: Res<Game>,
     wake: Res<WakeState>,
     mut mode: ResMut<RenderMode>,
@@ -3593,11 +3603,9 @@ fn update_camera_real(
     // Zoom bounds retune around the close default (material-dark-frame.md
     // criterion 5): min holds a tight rack close-up, max surveys lit
     // pools without the plan driving distance.
-    if kb.just_pressed(KeyCode::BracketRight) {
-        mode.zoom = (mode.zoom * 0.8).max(MIN_ZOOM);
-    }
-    if kb.just_pressed(KeyCode::BracketLeft) {
-        mode.zoom = (mode.zoom / 0.8).min(MAX_ZOOM);
+    let steps = zoom_steps(&kb, &mut mouse_wheel, &windows);
+    if steps != 0.0 {
+        mode.zoom = apply_zoom_steps(mode.zoom, steps, MIN_ZOOM, MAX_ZOOM);
     }
 
     let dist = CLOSE_DIST * mode.zoom;
@@ -4634,6 +4642,8 @@ fn execute_menu_row(game: &mut Game, row: &HumanMenuRow) {
 fn update_camera(
     time: Res<Time>,
     kb: Res<ButtonInput<KeyCode>>,
+    mut mouse_wheel: MessageReader<MouseWheel>,
+    windows: Query<&Window, With<PrimaryWindow>>,
     game: Res<Game>,
     mode: Res<RenderMode>,
     mut cam: Query<(&mut Transform, &mut Projection), With<GameCamera>>,
@@ -4646,11 +4656,9 @@ fn update_camera(
         return;
     };
     if let Projection::Orthographic(o) = &mut *proj {
-        if kb.just_pressed(KeyCode::BracketRight) {
-            o.scale = (o.scale * 0.8).max(0.25);
-        }
-        if kb.just_pressed(KeyCode::BracketLeft) {
-            o.scale = (o.scale / 0.8).min(1.5);
+        let steps = zoom_steps(&kb, &mut mouse_wheel, &windows);
+        if steps != 0.0 {
+            o.scale = apply_zoom_steps(o.scale, steps, MIN_FLAT_ZOOM, MAX_FLAT_ZOOM);
         }
     }
     let target = grid_to_world(game.cursor_x, game.cursor_y, tf.translation.z);
@@ -4658,6 +4666,55 @@ fn update_camera(
     tf.translation = tf.translation.lerp(target, t);
 }
 
+/// Return whether the pointer is over the independent right-rail scroll
+/// surface. Canvas wheel input belongs to camera zoom; rail wheel input belongs
+/// to scrolling and must never move the world camera underneath a reading hand.
+fn cursor_over_sidebar(windows: &Query<&Window, With<PrimaryWindow>>) -> bool {
+    windows
+        .single()
+        .ok()
+        .and_then(|window| window.cursor_position().map(|cursor| (window, cursor)))
+        .is_some_and(|(window, cursor)| cursor.x >= window.width() - SIDEBAR_WIDTH)
+}
+
+fn wheel_zoom_steps(unit: MouseScrollUnit, y: f32) -> f32 {
+    match unit {
+        MouseScrollUnit::Line => y,
+        MouseScrollUnit::Pixel => y / WHEEL_PIXELS_PER_ZOOM_STEP,
+    }
+}
+
+/// Positive input zooms in (smaller camera distance/orthographic scale);
+/// negative input zooms out. Both cameras deliberately share this mapping so
+/// F3 changes representation, not how a player navigates the shared canvas.
+fn apply_zoom_steps(current: f32, steps: f32, min: f32, max: f32) -> f32 {
+    (current * ZOOM_STEP.powf(steps)).clamp(min, max)
+}
+
+fn zoom_steps(
+    kb: &ButtonInput<KeyCode>,
+    mouse_wheel: &mut MessageReader<MouseWheel>,
+    windows: &Query<&Window, With<PrimaryWindow>>,
+) -> f32 {
+    let mut steps = 0.0;
+    if kb.just_pressed(KeyCode::BracketRight) {
+        steps += 1.0;
+    }
+    if kb.just_pressed(KeyCode::BracketLeft) {
+        steps -= 1.0;
+    }
+
+    let over_sidebar = cursor_over_sidebar(windows);
+    for event in mouse_wheel.read() {
+        if !over_sidebar {
+            // Winit reports wheel-up as positive Y. Positive input narrows
+            // the frame; wheel-down expands it.
+            steps += wheel_zoom_steps(event.unit, event.y);
+        }
+    }
+    steps
+}
+
 fn advance_sim(time: Res<Time>, mut clock: ResMut<SimClock>, mut game: ResMut<Game>) {
     if game.screen != Screen::Playing || game.paused {
         return;
@@ -5657,6 +5714,40 @@ mod input_routing_tests {
     }
 }
 
+#[cfg(test)]
+mod zoom_input_tests {
+    use super::{
+        MAX_ZOOM, MIN_ZOOM, WHEEL_PIXELS_PER_ZOOM_STEP, apply_zoom_steps, wheel_zoom_steps,
+    };
+    use bevy::input::mouse::MouseScrollUnit;
+
+    #[test]
+    fn keyboard_and_wheel_share_zoom_direction_and_bounds() {
+        let zoom_in = apply_zoom_steps(1.0, 1.0, MIN_ZOOM, MAX_ZOOM);
+        let zoom_out = apply_zoom_steps(1.0, -1.0, MIN_ZOOM, MAX_ZOOM);
+
+        assert!(zoom_in < 1.0, "positive input narrows the frame");
+        assert!(zoom_out > 1.0, "negative input expands the frame");
+        assert_eq!(
+            apply_zoom_steps(MIN_ZOOM, 100.0, MIN_ZOOM, MAX_ZOOM),
+            MIN_ZOOM
+        );
+        assert_eq!(
+            apply_zoom_steps(MAX_ZOOM, -100.0, MIN_ZOOM, MAX_ZOOM),
+            MAX_ZOOM
+        );
+    }
+
+    #[test]
+    fn pixel_scroll_scales_to_a_deliberate_fractional_step() {
+        assert_eq!(wheel_zoom_steps(MouseScrollUnit::Line, 1.0), 1.0);
+        assert_eq!(
+            wheel_zoom_steps(MouseScrollUnit::Pixel, WHEEL_PIXELS_PER_ZOOM_STEP / 2.0),
+            0.5
+        );
+    }
+}
+
 fn trunc(text: &str, width: usize) -> String {
     text.chars().take(width).collect()
 }
@@ -6050,7 +6141,8 @@ hover + 5-9 = action   e = menu
 click/drag multi-select
 trace: click a > event
 esc clear sel   space pause
-+/- speed   [ ] zoom   ^s/^l   q"
++/- speed   [ ]/wheel zoom
+wheel rail = scroll   ^s/^l   q"
 }
 
 fn update_compute_bar(sim: &Sim, bars: &mut ComputeBarQuery) {
@@ -6208,11 +6300,7 @@ fn scroll_sidebar(
 
     let range =
         (computed.content_size().y - computed.size().y).max(0.0) * computed.inverse_scale_factor();
-    let over_sidebar = windows
-        .single()
-        .ok()
-        .and_then(|window| window.cursor_position().map(|cursor| (window, cursor)))
-        .is_some_and(|(window, cursor)| cursor.x >= window.width() - SIDEBAR_WIDTH);
+    let over_sidebar = cursor_over_sidebar(&windows);
 
     let mut delta = 0.0;
     for event in mouse_wheel.read() {
diff --git a/wiki/interface/action-vocabulary.md b/wiki/interface/action-vocabulary.md
index f4f8b59b..7e91cb29 100644
--- a/wiki/interface/action-vocabulary.md
+++ b/wiki/interface/action-vocabulary.md
@@ -212,7 +212,7 @@ useful interface words, but they do not enlarge the fictional verb set.
 | **TIME CONTROL** | Human play pauses or changes wall-clock speed; agent play advances an exact number of ticks. | Space/p, +, - | `wait N` |
 | **INSPECT** | Render current state without creating a world effect. | Focus/rail/context surfaces | `look`, `people`, `reach`, `finance`, `research`, `objective`, `intents` |
 | **SAVE / LOAD** | Persist or restore the run. Only the complete chord captures input; a modifier alone is not a modal state. | Ctrl/Command+S / Ctrl/Command+L | `save`, `load` |
-| **VIEW CONTROL** | Change presentation only. | Bevy zoom, sidebar scroll, F3 render flip; F4 is dev-only | none |
+| **VIEW CONTROL** | Change presentation only. | Bevy `[` / `]` or canvas-wheel zoom, right-rail scroll, F3 render flip; F4 is dev-only | none |
 | **HELP / QUIT** | Explain accepted input or leave the process. | Hints / q | `help`, `quit` |
 
 Opening a panel, moving the cursor, selecting machines, and changing render
diff --git a/wiki/interface/bevy-digital-real-canvas.md b/wiki/interface/bevy-digital-real-canvas.md
index 15715ccc..d0202f41 100644
--- a/wiki/interface/bevy-digital-real-canvas.md
+++ b/wiki/interface/bevy-digital-real-canvas.md
@@ -186,6 +186,11 @@ frontend view choice anchored to the cursor, selected camera feed, or selected
 known cluster. The feel is "earned surveillance/model angle," not a god-camera
 pawn game.
 
+`[` / `]` and mouse/trackpad wheel over the canvas zoom both representations
+around that same anchor. Wheel input over the right rail remains rail scrolling,
+not camera motion. Zoom is frontend-only: it changes no sim state, selection,
+knowledge, or physical anchor.
+
 ## Fog contract
 
 Fog states keep the cursor.md epistemic contract in both dialects:
diff --git a/wiki/interface/bevy.md b/wiki/interface/bevy.md
index 08173047..4c1bced7 100644
--- a/wiki/interface/bevy.md
+++ b/wiki/interface/bevy.md
@@ -81,7 +81,8 @@ of the whole 64×36 grid every frame.
   same fog rule as the terminal (`Seen` / `Heard` /
   `Remembered` / `Blueprint` / `Unknown`). The process has no walking body:
   the always-visible marker is the frontend-only cursor, the camera follows
-  it, mouse-clicks retarget it, and `[` / `]` zoom. In the material render
+  it, mouse-clicks retarget it, and `[` / `]` or the canvas mouse/trackpad
+  wheel zoom. In the material render
   the default is an attention-close frame (material-dark-frame.md), not
   fit-to-known-content; the flat sensorium keeps the fit-to-content default.
 - **People markers** — a person's first initial, rendered only while a
@@ -130,10 +131,11 @@ of the whole 64×36 grid every frame.
   at light intensity and widens/brightens at hard. Emissive carries
   information: the core, powered machines (amber), power hardware and live
   feeds (cold signal, live feeds breathing), dead equipment dark. Materials
-  are pooled by tile/fog/part/live-feed. `[` / `]` retune the zoom around the
-  close default; `F4` toggles the dev work light (a flat neutral flood, not a
-  player surface). F3 flips to the flat sensorium render; the mode is not
-  saved and changes no sim state.
+  are pooled by tile/fog/part/live-feed. `[` / `]` or the canvas
+  mouse/trackpad wheel retune the zoom around the close default; wheel input
+  over the right rail remains sidebar scrolling. `F4` toggles the dev work
+  light (a flat neutral flood, not a player surface). F3 flips to the flat
+  sensorium render; the mode is not saved and changes no sim state.
 - **Overlays** — title card and the RUN ENDED card (reason, day / tick).
 
 Text remains ASCII-only because Bevy's embedded default font carries a limited
@@ -151,11 +153,11 @@ Identical to the terminal ([interface/terminal.md](terminal.md), README
 controls table), plus zoom, sidebar scrolling, and the render flip:
 
 - Move cursor `WASD` / `hjkl` / arrows, or left-click the map; pause
-  `SPACE`/`p`; speed `+`/`-`; zoom `[` / `]`; scroll the right sidebar with
-  mouse wheel over the pane, `PageUp`/`PageDown`, or `Home`/`End`; F3 flips
-  material/sensorium; F4 toggles the dev work light (material mode only, a
-  flat neutral flood for inspection, not a player surface); quit `q`;
-  save/load `Ctrl+S` / `Ctrl+L`.
+  `SPACE`/`p`; speed `+`/`-`; zoom `[` / `]` or wheel over the canvas; scroll
+  the right sidebar with wheel input over that pane, `PageUp`/`PageDown`, or
+  `Home`/`End`; F3 flips material/sensorium; F4 toggles the dev work light
+  (material mode only, a flat neutral flood for inspection, not a player
+  surface); quit `q`; save/load `Ctrl+S` / `Ctrl+L`.
 - Persistence modifiers are chord-local rather than modal. Only a complete
   Ctrl/Command+S or Ctrl/Command+L chord captures the frame; a bare modifier
   state never suppresses unrelated controls. This keeps macOS native overlays
diff --git a/wiki/log/2026-07-10-bevy-canvas-zoom.md b/wiki/log/2026-07-10-bevy-canvas-zoom.md
new file mode 100644
index 00000000..7ff1b53c
--- /dev/null
+++ b/wiki/log/2026-07-10-bevy-canvas-zoom.md
@@ -0,0 +1,31 @@
+# Bevy canvas-wheel zoom — 2026-07-10
+
+```
+Type: log
+```
+
+## What changed
+
+- Added mouse/trackpad-wheel zoom to the Bevy canvas alongside the existing
+  `[` / `]` controls. Wheel-up narrows the frame; wheel-down expands it.
+- Kept the right rail unambiguous: wheel input over that pane scrolls the rail
+  and never changes the camera beneath it.
+- Both material and flat-sensorium cameras share the same input direction and
+  bounded multiplicative zoom behavior, so F3 changes representation rather
+  than navigation vocabulary.
+
+## Evidence
+
+- `crates/misaligned-bevy/src/main.rs` owns the frontend-only `RenderMode`
+  camera distance and flat orthographic projection. It receives the same
+  `MouseWheel` stream the sidebar already consumes independently.
+- `wiki/interface/bevy-digital-real-canvas.md` requires both dialects to stay
+  on one anchor-grounded canvas and prohibits camera motion from changing sim
+  state.
+
+## Defense
+
+`wiki/interface/bevy-digital-real-canvas.md#camera-and-depth-contract`:
+camera movement is a frontend view choice anchored to the same shared canvas.
+This change adds an accessible input path only; it introduces no sim, save,
+knowledge, or selection state.
diff --git a/wiki/log/DEVLOG.md b/wiki/log/DEVLOG.md
index c8018cad..b42c40ae 100644
--- a/wiki/log/DEVLOG.md
+++ b/wiki/log/DEVLOG.md
@@ -351,6 +351,11 @@ add or amend a session log, then re-run the generator.
 - Intent: The material frontend was paying full restyle/UI cost every display frame: `advance_sim` held `ResMut<Game>` and ticked a timer on `Game` every frame, so `game.is_changed()` stayed true and `restyle_3d` / `render_map` / `render_ui` rebuilt continuously.
 - Log: [wiki/log/2026-07-10-bevy-perf-pass.md](2026-07-10-bevy-perf-pass.md)
 
+## 2026-07-10 - Bevy canvas-wheel zoom — 2026-07-10
+
+- Intent: (see session log)
+- Log: [wiki/log/2026-07-10-bevy-canvas-zoom.md](2026-07-10-bevy-canvas-zoom.md)
+
 ## 2026-07-10 - Allow AI attribution in commits
 
 - Intent: Remove the repository-specific prohibition on crediting AI contributors in commit messages. Cameron decided that accurate AI attribution is acceptable; the existing plain-message and explicit-staging rules remain.
-- 
2.51.2