Add detailed phase plans for foundational macrosteps

- Macrostep 00: Model contract and retained historical options.
- Macrostep 01: Project foundation and configuration, including schema, presets, CLI, and CI setup.
- Macrostep 02: Mathematical core implementation and deterministic oracles.
- Macrostep 03: CPU-based planar simulation engine, FFT backend, and headless runner.

Provides exhaustive objectives, phase breakdowns, validation policies, and deliverables for each macrostep.

plans/04_raylib_visualization_workbench.md

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+# Macrostep 04 — Raylib visualization workbench
+
+## Objective
+
+Deliver the first useful interactive product: a portable, resize-safe raylib laboratory that runs the CPU backend and makes the rule, kernels, neighborhoods, and update logic visible.
+
+## Dependencies
+
+Macrosteps 00–03 complete.
+
+## Phase 4.1 — Application lifecycle and scheduler
+
+### Substep 4.1.1 — Raylib ownership
+
+Initialize and own raylib on the main thread. Keep handles out of the mathematical core. Establish explicit startup, running, backend-rebuild, and shutdown states so partial resource failures do not corrupt the model.
+
+### Substep 4.1.2 — Decoupled timing
+
+Implement:
+
+- render FPS independent of a fixed updates-per-second simulation clock;
+- pause, single-step, reset, and an explicit finite `advance N steps` command that is not tied to rendering;
+- bounded catch-up to avoid a spiral of death;
+- headless benchmarking outside the render loop rather than an uncapped frame-driven mode;
+- model `dt` independent of wall-clock tick duration.
+
+Animations and camera movement are time-based, not frame-count-based.
+
+### Substep 4.1.3 — Unified action map
+
+Map keyboard, mouse, and UI widgets to one `Action` enum. Retain practical legacy aliases (`p`, `c`, `x/y`, parameter pairs, preset cycling), but do not encode behavior directly in key handlers. Add a searchable/help overlay.
+
+## Phase 4.2 — Shared presentation primitives
+
+### Substep 4.2.1 — Scalar texture uploader
+
+Convert CPU scalar fields to reusable raylib textures without allocating every frame. Start with a portable normalized or packed upload path; retain original `f32` values in the model. Make filtering (`nearest` default, optional linear) explicit.
+
+### Substep 4.2.2 — Palettes
+
+Implement named versions of all seven legacy palettes in one shared Rust/GLSL definition:
+
+1. phase hue on black;
+2. white on black;
+3. black on white;
+4. value rainbow;
+5. brown/green;
+6. gold/brown;
+7. phase-shifted value rainbow.
+
+Sanitize palette inputs and show a legend/range. Palette phase changes in units per second.
+
+### Substep 4.2.3 — Cameras
+
+- 2-D uses a coherent `Camera2D`, cursor-centered wheel zoom, drag pan, reset, and fit-to-view.
+- 1-D and 3-D placeholders use their own presentation state; do not overload simulation coordinates.
+- Window resize changes presentation only, never simulation shape or state.
+
+## Phase 4.3 — Model and logic views
+
+### Substep 4.3.1 — Live state
+
+Render the selected field at correct aspect ratio with periodic coordinate indicators. Display generation, update rate, render FPS, shape, seed, preset, dynamics, integrator, and backend.
+
+### Substep 4.3.2 — Read-only inspection
+
+Provide a tab/grid selector for:
+
+- `A`, `M`, `N`, `S`, derivative/increment, and proposed next state;
+- raw/normalized disk and ring kernels;
+- rule surface `S(N,M)` with labeled axes and current `(N,M)` probe;
+- radial kernel profile and numeric value-under-cursor.
+
+Inspection never modifies state. Keep `c` as an optional “next primary view” shortcut.
+
+### Substep 4.3.3 — Compare layout
+
+Support at least a two-pane mode, for example `A | S`, `M | N`, or `kernel | radial profile`. All panes refer to the same committed generation and show stale-generation warnings if an async backend is introduced later.
+
+## Phase 4.4 — Configuration UI
+
+Build a collapsible raylib-native panel (or a deliberately selected raygui binding after a compatibility spike) with sections:
+
+- run/preset/variant;
+- domain and initializer;
+- rule intervals and curves;
+- dynamics/integrator/timestep and RK4 relaxation reference when applicable;
+- kernel geometry;
+- backend, FFT algorithm, and performance;
+- view/palette/camera;
+- capture and diagnostics.
+
+Classify edits visibly:
+
+- **Hot:** presentation and pointwise rule edits; apply immediately.
+- **Warm:** kernel geometry/timestep/integrator; rebuild caches and invalidate integration history as specified.
+- **Cold:** shape, topology, variant, or backend; require transactional recreate/apply.
+
+Provide sliders plus precise numeric entry. Show validation inline; never silently clamp model parameters to UI ranges.
+
+## Phase 4.5 — Presets, sessions, and capture
+
+### Substep 4.5.1 — Preset browser
+
+Filter by variant/dimension/tags, show provenance and notes, and indicate modified (“dirty”) parameters. Applying a preset is transactional and logs the resulting run descriptor.
+
+### Substep 4.5.2 — Persistence
+
+Persist user preferences separately from model presets. Add “save as user preset,” not append-to-bundled-file behavior. Save enough precision for exact round trips.
+
+### Substep 4.5.3 — Exports
+
+Provide:
+
+- viewport PNG, optionally with HUD;
+- native field image with active palette;
+- restart-state export (field plus metadata, numerical history resets on load);
+- exact continuation checkpoint with integrator/variant history;
+- metadata sidecar containing run descriptor and generation.
+
+Use collision-safe timestamp/sequence names in the platform pictures/data directory.
+
+## Phase 4.6 — Robustness and UX tests
+
+- Resize/minimize/fullscreen/high-DPI smoke tests.
+- Launch from arbitrary working directories.
+- Repeated valid/invalid warm and cold edits.
+- Pause and single-step accuracy.
+- Screenshot/state export while paused and running.
+- Keyboard focus does not alter parameters while numeric input is active.
+- Visible fallback if texture/shader creation fails.
+
+## Deliverables
+
+- Portable raylib application using the CPU planar backend.
+- Discoverable controls, inspectors, preset browser, and exports.
+- Stable action, camera, palette, and presentation abstractions for later variants.
+
+## Exit gate
+
+- A user can launch, choose a preset, reset with a seed, run/pause/step, edit parameters, and inspect every base pipeline channel.
+- Headless and interactive CPU runs produce identical model states for equal commands.
+- Resize and fullscreen never reset simulation.
+- No inspection mode destroys or advances state.
+- The application works outside the repository and reports failures visibly.