webeditor3d/prompts.txt

These prompts assume the repo docs are already updated.
Use one fresh Codex chat per prompt.
Each prompt is written to be copy-paste ready.

---

## Prompt 0 — Repo foundation / bootstrap

```text
You are working in a new repo for a browser-based brush editor + built-in runner for lightweight interactive 3D scenes.

Read and follow these files first:
- AGENTS.md
- architecture.md
- roadmap.md
- testing.md

Before coding:
- Inspect the current repo and extend what is there.
- Do not re-architect unless the current code clearly violates the docs.
- Keep the repo as a single Vite app with domain folders under src/.
- Do not use the React tree as the canonical state container.

Your task is to implement the foundation slice only.

Goals:
- Bootstrap the project with React + Vite + TypeScript.
- Set up a minimal app shell with a visible three.js viewport region and placeholder side panels.
- Add strict TypeScript config, lint/format scaffolding if missing, and a small folder structure under src/ that matches the architecture docs.
- Add a minimal versioned canonical SceneDocument model.
- Add a migration entry point, even if it only handles the current version.
- Add a minimal Command interface and CommandHistory with undo/redo support.
- Add a thin external editor store/service that owns the document, selection, tool mode, and command history.
- Add local draft save/load scaffolding for the empty document.
- Add explicit JSON import/export scaffolding for the document.
- Add test setup for Vitest and Playwright.
- Add one smoke test that proves the app boots and the viewport shell is visible.
- Do not implement real geometry tools yet.
- Do not overbuild infrastructure.
- Do not add React Three Fiber.
- Do not split into a monorepo.

Expected output:
- A working app that starts locally.
- A visible layout with a center viewport and side panels.
- A minimal empty document factory.
- A command stack that can handle at least a dummy command.
- Basic scripts in package.json for dev, build, test, test:e2e, and typecheck.
- Initial test files.
- Small, coherent file structure.

Constraints:
- Keep the canonical document independent from three.js objects.
- Keep the viewport imperative and plain three.js.
- Keep the implementation as small as possible while preserving architecture seams.
- Avoid speculative plugin systems or ECS.
- If you introduce persisted schema, version it from day one.

Please:
1. Inspect the repo.
2. Implement the slice fully.
3. Update any missing config/scripts.
4. Run the relevant build/tests locally if possible.
5. At the end, report:
   - what changed
   - why it changed
   - which files were added/updated
   - how to run it
   - what was verified
   - known limitations
```

---

## Prompt 1 — Box brush authoring

```text
You are implementing the first real vertical slice of a browser-based brush editor.

Read and follow:
- AGENTS.md
- architecture.md
- roadmap.md
- testing.md

Before coding:
- Inspect the current repo and extend the existing implementation.
- Do not re-architect unless the current code clearly violates the docs.
- If you change the persisted SceneDocument schema, update versioning, migrations, and at least one migration/compatibility test.

Current goal:
Implement Slice 1.1 — Box brush authoring.

Requirements:
- Add canonical BoxBrush support to the SceneDocument.
- Keep early box brushes axis-aligned only.
- Do not implement arbitrary brush rotation in this slice.
- Unless the repo already has a compatible equivalent, represent a box brush canonically as:
  - `kind: "box"`
  - `center`
  - positive `size`
  - stable face records keyed by `posX | negX | posY | negY | posZ | negZ`
- Implement create/select/move/resize for box brushes.
- Add grid snapping.
- Render box brushes in the three.js editor viewport.
- Add outliner presence for brushes.
- Ensure save/load JSON works for box brushes.
- Add undo/redo support through commands for all authoring actions in this slice.
- Keep the box brush stored canonically as structured brush data, not raw triangle soup.
- Keep editor mesh generation derived from canonical brush data.
- Keep the UI simple and real. Button-driven creation is acceptable if it is usable.
- Do not implement face UV editing yet.
- Do not implement fancy primitives yet.

Testing expectations:
- Unit/domain tests for create box brush command and undo/redo
- Serialization round-trip test for a document with at least one box brush
- Browser/e2e smoke proving a user can create a box brush and it persists after reload through the current persistence path
- Geometry sanity tests if you introduce a mesh builder

Important architecture rules:
- Document is source of truth
- Commands own mutations
- three.js scene is derived
- No raw three.js objects in the document
- No R3F

Deliverables:
- End-to-end usable box brush slice
- Any small UI needed to exercise it
- Tests
- Brief manual QA notes in your response

Please implement this slice completely, run the relevant checks if possible, and then report:
- changed files
- commands added
- how box brush canonical data is represented
- how to test/use it
- what remains intentionally out of scope
```

---

## Prompt 2 — Face materials and UV basics

```text
You are implementing Slice 1.2 — Face materials and UV basics.

Read and follow:
- AGENTS.md
- architecture.md
- roadmap.md
- testing.md

Before coding:
- Inspect the current repo and extend the existing implementation.
- Do not re-architect unless the current code clearly violates the docs.
- If you change persisted schema, update versioning, migrations, and at least one compatibility test.

Current goal:
Make it possible to assign materials to individual box brush faces and edit basic UV parameters.

Requirements:
- Introduce a canonical material registry in the document.
- Add a tiny starter material library stored locally in the repo.
- Add face selection for box brushes using the stable box face IDs.
- Allow applying a material to a single face.
- Persist explicit UV state canonically per face using concrete values.
- Unless the repo already has a compatible equivalent, store these per-face UV fields:
  - `offset`
  - `scale`
  - `rotationQuarterTurns`
  - `flipU`
  - `flipV`
- Support these operations:
  - offset
  - scale
  - rotate 90
  - flip U
  - flip V
  - fit to face
- Treat “fit to face” as a command that rewrites explicit UV values.
- Do not persist a separate procedural fit flag yet.
- Persist all face material and UV data through save/load.
- Reflect material and UV changes in viewport rendering.
- Add a minimal material browser panel and/or inspector controls.
- Keep UV state canonical in the document, not only in generated mesh UV buffers.
- Do not overcomplicate the material system yet.
- Do not build a huge texture pipeline yet.

Important:
- A major goal is to preserve Hammer/TrenchBroom-style speed.
- The UX can be simple at first, but it must be real and usable.
- Commands must cover material application and UV edits so undo/redo works.

Testing expectations:
- Round-trip save/load test with per-face material + UV state
- Domain tests for apply-material and UV edit commands
- Geometry/render tests if useful for derived UV output
- Browser/e2e test for assigning a face material through the UI if feasible

Implementation guidance:
- Keep the starter material library small and local to the project
- Prefer simple thumbnails / labels over overdesigned UI
- Keep face identification stable in the canonical box brush representation

Please implement the slice fully and report:
- how face IDs are represented
- how UV state is stored
- what UI affordances were added
- what tests were added
- how to verify manually
```

---

## Prompt 3 — Runner v1

```text
You are implementing Slice 1.3 — Runner v1.

Read and follow:
- AGENTS.md
- architecture.md
- roadmap.md
- testing.md

Before coding:
- Inspect the current repo and extend the existing implementation.
- Do not re-architect unless the current code clearly violates the docs.
- If you change persisted schema, update versioning, migrations, and at least one compatibility test.

Current goal:
Make the authored scene playable inside the browser.

Requirements:
- Add a runtime build step from SceneDocument to a runtime scene representation.
- Add a built-in runner/play mode reachable from the editor.
- Support:
  - first-person navigation
  - orbit visitor mode
- First-person can be simple, but should feel real:
  - `WASD` movement
  - mouse-look when active
  - graceful pointer-lock failure handling
- Orbit visitor should provide a clear fallback for non-FPS navigation.
- Add minimal typed PlayerStart support in a way that is compatible with the later full entity system.
- Add basic collision against axis-aligned box-brush-generated geometry, enough for a small room test.
- Allow entering and leaving run mode safely.
- Preserve editor state when leaving run mode.
- Keep the runner as a sibling system, not a hack inside editor-only viewport code.
- Do not add triggers or audio yet.
- Do not add future nav modes yet.

Implementation guidance:
- Reuse three.js where appropriate, but keep runtime-specific logic separate from editor helpers.
- Keep collision deterministic and explicit about limitations.
- PlayerStart should become part of the canonical document, not an editor-only setting.

Testing expectations:
- Domain/build tests for runtime scene construction from a simple document
- E2E/smoke test that enters run mode successfully
- If possible, a minimal interaction test that the player spawns at PlayerStart

Please implement the slice fully and report:
- what runtime modules/classes were added
- how edit mode and run mode are separated
- how PlayerStart is represented
- known limitations of collision/movement
- how to run and verify manually
```

---

## Prompt 4 — End-to-end first-room polish

```text
You are implementing Slice 1.4 — polish for the first complete room workflow.

Read and follow:
- AGENTS.md
- architecture.md
- roadmap.md
- testing.md

Before coding:
- Inspect the current repo and extend the existing implementation.
- Do not redesign the product or rewrite earlier slices.
- If you change persisted schema, update versioning, migrations, and at least one compatibility test.

Current goal:
Strengthen the first real user loop:
create box brush -> texture faces -> save/load -> run scene.

Requirements:
- Add basic document validation and visible validation/build errors.
- Improve snapping feedback and active-tool feedback.
- Add a minimal toolbar or command surface for key authoring actions.
- Improve save/load UX enough that the first-room workflow feels coherent.
- Add or refine scene/world settings only if needed for the first-room slice.
- Tighten rough edges in the editor/runner transition.
- Add smoke/regression coverage for the first-room loop.

Minimum validation scope:
- duplicate IDs
- invalid box sizes
- missing material refs
- invalid entity refs introduced so far
- missing PlayerStart when entering first-person mode, if that matters in the current implementation

Important:
- This is not a redesign pass.
- This is not a “make it pretty” pass.
- It is a coherence and trust pass.
- Prioritize usability, error visibility, and slice completeness.

Testing expectations:
- E2E flow for create -> texture -> save/load -> run
- Validation tests for obvious bad states
- Missing regression tests for the first-room loop

Please implement only what materially improves the first-room workflow and report:
- UX improvements made
- validation/build diagnostics added
- tests added
- manual QA flow you used
```

---

## Prompt 5 — Entity system foundation

```text
You are implementing Slice 2.1 — Entity system foundation.

Read and follow:
- AGENTS.md
- architecture.md
- roadmap.md
- testing.md

Before coding:
- Inspect the current repo and extend the existing implementation.
- Reuse and extend the existing PlayerStart path rather than rebuilding it in parallel.
- Do not merge model instances into entities.
- If you change persisted schema, update versioning, migrations, and at least one compatibility test.

Current goal:
Add a typed entity system to the editor and runtime foundation.

Initial entity types to support:
- PlayerStart
- SoundEmitter
- TriggerVolume
- TeleportTarget
- Interactable

Requirements:
- Add explicit typed entity schemas to the canonical document model.
- Add an entity registry/defaults layer.
- Add an entity placement workflow.
- Add viewport helpers/icons/gizmos for entities.
- Add entity selection and inspector editing.
- Persist entities through save/load.
- Make runtime build consume entities, even if only some are active yet.
- Keep entities typed; do not implement a generic script blob system.
- Keep editor visuals for entities separate from runtime behavior.
- Keep model instances, if any exist already, in their own collection.

Implementation guidance:
- Keep the first version small and explicit.
- Use clear defaults and property validation.
- Ensure entity IDs and references are stable.

Testing expectations:
- Domain tests for entity creation/editing
- Serialization round-trip tests
- Browser/e2e test for placing and selecting an entity if feasible

Please implement fully and report:
- entity types added
- how the registry/defaults work
- how placement works
- how entities appear in viewport/outliner/inspector
- what runtime integration exists so far
```

---

## Prompt 6 — Trigger -> Action -> Target foundation

```text
You are implementing Slice 2.2 — Trigger -> Action -> Target foundation.

Read and follow:
- AGENTS.md
- architecture.md
- roadmap.md
- testing.md

Before coding:
- Inspect the current repo and extend the existing implementation.
- Do not build a generic scripting system or node graph.
- If you change persisted schema, update versioning, migrations, and at least one compatibility test.

Current goal:
Enable the first simple data-driven interactions without scripting.

Requirements:
- Add canonical schemas for trigger/action/target links.
- Unless the repo already has a compatible equivalent, represent links as explicit records with:
  - stable link ID
  - source entity ID
  - trigger kind
  - typed action payload
- Support authoring and persistence of these links.
- Add runtime evaluation of trigger -> action -> target.
- Add minimal UI for configuring links in the inspector.
- Keep the system typed and explicit.

Initial supported trigger sources:
- TriggerVolume enter
- TriggerVolume exit

Initial supported actions:
- teleport player
- toggle visibility

Important:
- Keep it data-driven, not script-driven.
- Do not activate sound or animation actions yet.
- Do not build a generic node graph.
- Do not overdesign event buses.
- Focus on the smallest real interaction system that works end-to-end.

Testing expectations:
- Domain tests for link validation
- Runtime tests for dispatch behavior with fixtures or mocks
- E2E/manual verification for at least one actual trigger flow

Please implement the slice fully and report:
- how links are stored canonically
- which trigger types and actions are active now
- how runtime dispatch works
- how to test an example interaction
- known limitations
```

---

## Prompt 7 — Click interactions and runner prompts

```text
You are implementing Slice 2.3 — Click interactions and runner prompts.

Read and follow:
- AGENTS.md
- architecture.md
- roadmap.md
- testing.md

Before coding:
- Inspect the current repo and extend the existing implementation.
- Preserve compatibility with the current Trigger -> Action -> Target system.
- If you change persisted schema, update versioning, migrations, and at least one compatibility test.

Current goal:
Allow the user to click interactive entities in run mode and receive clear prompts/feedback.

Requirements:
- Add click-target support in the runner.
- Add a minimal prompt / interaction UI.
- Support action-on-click behavior for Interactable entities.
- Add interaction distance and basic targeting rules.
- Keep behavior deterministic and understandable.
- Preserve compatibility with the existing Trigger -> Action -> Target system.
- Separate runtime input handling from editor picking.

Implementation guidance:
- Keep the UI minimal and legible.
- Prefer explicit interaction affordances over hidden magic.
- Interaction range should be a clear authored/configured value or a simple documented default.

Testing expectations:
- Runtime/browser tests for click targeting
- E2E or manual verification for click-to-trigger flow
- Regression coverage for prompt visibility logic if practical

Please implement fully and report:
- how click targeting works
- what prompt UX was added
- how interaction range is defined
- how to verify manually
```

---

## Prompt 8 — GLB/GLTF import

```text
You are implementing Slice 3.1 — GLB/GLTF import.

Read and follow:
- AGENTS.md
- architecture.md
- roadmap.md
- testing.md

Before coding:
- Inspect the current repo and extend the existing implementation.
- Keep placed imported models separate from entities.
- If you change persisted schema, update versioning, migrations, and at least one compatibility test.

Current goal:
Import GLB/GLTF assets, register them, and place them in the scene.

Requirements:
- Add an asset registry to the canonical document or asset domain.
- Implement a GLB/GLTF import workflow.
- Add the smallest reliable project-storage addition needed so imported assets survive reload.
- Prefer IndexedDB-backed project asset storage for binary payloads if browser storage is needed.
- Keep stable asset records in the canonical document.
- Never rely on ephemeral Blob URLs as the only persisted reference.
- Extract and store useful metadata:
  - asset id
  - name
  - stable persistence reference
  - contained materials/textures if useful
  - animations list if present
  - bounding box / dimensions if feasible
- Add preview/thumbnail support if practical, but do not let thumbnail generation block import.
- Allow placing an imported model instance in the scene.
- Allow selecting and transforming a model instance.
- Persist asset references and placed model instances through save/load.
- Render imported assets in editor and runner.

Important:
- Imported assets should be first-class but must not replace brushes.
- Distinguish clearly between asset records and scene model instances.
- Keep the implementation small and reliable.
- Do not build a giant asset-management subsystem yet.

Testing expectations:
- Round-trip tests for asset refs / placed model instances
- At least one fixture GLB/GLTF test asset
- E2E or browser verification for import and placement if possible

Please implement fully and report:
- asset registry design
- model instance representation
- what metadata is extracted
- what limitations exist on import
- how to test with the included fixture(s)
```

---

## Prompt 9 — Animation playback

```text
You are implementing Slice 3.2 — Animation playback.

Read and follow:
- AGENTS.md
- architecture.md
- roadmap.md
- testing.md

Before coding:
- Inspect the current repo and extend the existing implementation.
- Reuse the existing Trigger -> Action -> Target system rather than inventing a second dispatch path.
- If you change persisted schema, update versioning, migrations, and at least one compatibility test.

Current goal:
Enable playback of animations from imported GLB/GLTF assets.

Requirements:
- Detect and surface imported animations in asset metadata and/or model instance config.
- Add a way to configure an animation target or animated model instance.
- Integrate animation playback into the runner.
- Add `play animation` and `stop animation` action wiring through the existing interaction system.
- Add minimal inspector UI needed to choose or inspect animation clips.
- Persist animation-related settings through save/load.
- Keep it small and explicit.
- Do not build a full timeline editor.

Testing expectations:
- Tests for imported animation metadata availability
- Runtime tests for play/stop dispatch if feasible
- Manual or e2e verification using a small animated fixture

Please implement fully and report:
- how animations are exposed to the author
- how runtime playback is managed
- what actions are supported
- how to test it
```

---

## Prompt 10 — Spatial audio

```text
You are implementing Slice 3.3 — Spatial audio.

Read and follow:
- AGENTS.md
- architecture.md
- roadmap.md
- testing.md

Before coding:
- Inspect the current repo and extend the existing implementation.
- Reuse the existing Trigger -> Action -> Target system rather than inventing a second dispatch path.
- If you change persisted schema, update versioning, migrations, and at least one compatibility test.

Current goal:
Make positional/spatial audio a first-class runner feature.

Requirements:
- Support audio asset references for SoundEmitter entities.
- Add the smallest reliable project-storage addition needed so imported audio survives reload if that does not already exist.
- Prefer reusing any existing project asset storage introduced for GLB/GLTF import.
- Implement positional audio in the runner.
- Support at least:
  - loop
  - one-shot or triggered playback
  - volume
  - ref distance
  - max distance if applicable
- Handle browser audio unlock / user gesture requirements gracefully.
- Integrate with existing trigger/action flows.
- Add `play sound` and `stop sound` actions to the existing interaction system.
- Add minimal inspector controls for sound settings.
- Persist all relevant settings through save/load.

Important:
- Spatial audio is a core product feature.
- Keep the authoring flow understandable.
- Don’t attempt advanced occlusion or buses yet.

Testing expectations:
- Domain tests for sound entity config
- Runtime tests for action dispatch into the audio system where practical
- Manual QA notes for real spatial verification
- Browser behavior notes for audio unlock

Please implement fully and report:
- audio system structure
- entity fields added/used
- how browser unlock is handled
- what was tested automatically vs manually
```

---

## Prompt 11 — Wedge/ramp and cylinder prism

```text
You are implementing the first additional brush-primitive slice.

Read and follow:
- AGENTS.md
- architecture.md
- roadmap.md
- testing.md

Before coding:
- Inspect the current repo and extend the existing implementation.
- Keep generated mesh derived from canonical primitive data.
- If you change persisted schema, update versioning, migrations, and at least one compatibility test.

Current goal:
Add two more canonical brush primitives:
- wedge / ramp
- cylinder prism

Requirements:
- Add canonical representation for each primitive.
- Add creation workflows.
- Add viewport rendering.
- Ensure save/load support.
- Ensure runner/runtime build support.
- Reuse existing material/face systems where possible.
- Keep primitive authoring simple and explicit.
- Do not introduce arbitrary mesh editing.

Important:
- Geometry robustness matters more than flashy UI.
- It is acceptable to ship these two primitives now and leave stairs/arch for later prompts.

Testing expectations:
- Strong geometry tests for each primitive
- Serialization round-trip tests
- Manual verification in viewport and runner

Please implement fully and report:
- canonical schema for each primitive
- creation UX
- any limitations in face/material support
- what tests protect geometry correctness
```

---

## Prompt 12 — Stairs primitive

```text
You are implementing the stairs brush primitive as its own vertical slice.

Read and follow:
- AGENTS.md
- architecture.md
- roadmap.md
- testing.md

Before coding:
- Inspect the current repo and extend the existing implementation.
- Keep generated mesh derived from canonical primitive data.
- If you change persisted schema, update versioning, migrations, and at least one compatibility test.

Current goal:
Add a canonical stairs primitive.

Requirements:
- Add canonical representation for stairs.
- Add creation workflow.
- Add viewport rendering.
- Ensure save/load support.
- Ensure runner/runtime build support.
- Reuse existing material/face systems where possible.
- Keep authoring explicit and understandable.
- Define step-count and size constraints clearly.

Important:
- Geometry robustness matters more than flashy UI.
- Do not introduce arbitrary mesh editing.

Testing expectations:
- Dense geometry tests for stairs
- Serialization round-trip tests
- Manual verification in viewport and runner

Please implement fully and report:
- canonical schema
- creation UX
- any limitations in face/material support
- what tests protect geometry correctness
```

---

## Prompt 13 — Arch primitive

```text
You are implementing the arch brush primitive as its own vertical slice.

Read and follow:
- AGENTS.md
- architecture.md
- roadmap.md
- testing.md

Before coding:
- Inspect the current repo and extend the existing implementation.
- Keep generated mesh derived from canonical primitive data.
- If you change persisted schema, update versioning, migrations, and at least one compatibility test.

Current goal:
Add a canonical arch primitive.

Requirements:
- Add canonical representation for an arch primitive.
- Add creation workflow.
- Add viewport rendering.
- Ensure save/load support.
- Ensure runner/runtime build support.
- Reuse existing material/face systems where possible.
- Keep authoring explicit and deterministic.
- Define any segment-count or thickness constraints clearly.

Important:
- Geometry robustness matters more than flashy UI.
- Do not introduce arbitrary mesh editing.

Testing expectations:
- Dense geometry tests for the arch
- Serialization round-trip tests
- Manual verification in viewport and runner

Please implement fully and report:
- canonical schema
- creation UX
- any limitations in face/material support
- what tests protect geometry correctness
```

---

## Prompt 14 — Constrained brush clipping

```text
You are implementing a constrained v1 brush clipping slice.

Read and follow:
- AGENTS.md
- architecture.md
- roadmap.md
- testing.md

Before coding:
- Inspect the current repo and extend the existing implementation.
- Do not introduce a full convex-brush system in this slice.
- If you change persisted schema, update versioning, migrations, and at least one compatibility test.

Current goal:
Add a clip tool with predictable, undoable results under explicit constraints.

Requirements:
- Add a clip tool workflow.
- Support at least:
  - preview of the clip plane/line
  - split brush or keep one side
- Store results as valid canonical brushes using currently supported brush kinds only.
- Preserve material/face information as sensibly as possible for v1.
- Ensure undo/redo is robust.
- Ensure clipped brushes save/load and run correctly.

Scope constraint:
- Prefer a first version that clips only axis-aligned box brushes with principal-axis clip planes if that keeps the implementation reliable.
- Unsupported cases must fail clearly in the UI.

Important:
- This is a high-risk geometry feature.
- Prefer a smaller but reliable implementation over an ambitious one.
- Be explicit about unsupported cases.

Testing expectations:
- Geometry tests for clip results
- Command tests for undo/redo
- Manual QA for common clip flows

Please implement fully and report:
- how clipping works internally
- what user workflow exists
- what constraints/unsupported cases remain
- what tests were added
```

---

## Prompt 15 — Better viewport layouts

```text
You are implementing the viewport-layout ergonomics slice.

Read and follow:
- AGENTS.md
- architecture.md
- roadmap.md
- testing.md

Before coding:
- Inspect the current repo and extend the existing implementation.
- Avoid rewriting the whole viewport architecture unnecessarily.

Current goal:
Improve level-authoring ergonomics with classic editor-style view support.

Requirements:
- Add orthographic top/front/side views.
- If feasible, add a split multi-view layout.
- Improve camera/control ergonomics.
- Improve snapping feedback if needed to support these views.
- Preserve existing selection and tool behavior across views as much as possible.

Important:
- This slice is about workflow speed.
- Keep the implementation understandable.
- Avoid rewriting the whole viewport architecture unnecessarily.

Testing expectations:
- Browser/manual verification for view switching and basic authoring
- Any integration tests that are stable and worth adding

Please implement fully and report:
- which view modes/layouts were added
- how camera handling is structured
- what manual QA scenarios were used
- any remaining rough edges
```

---

## Prompt 16 — Better material library

```text
You are implementing Slice 5.1 — Better material library.

Read and follow:
- AGENTS.md
- architecture.md
- roadmap.md
- testing.md

Before coding:
- Inspect the current repo and extend the existing implementation.
- Preserve compatibility with the existing face-assignment workflow.
- If you change persisted schema, update versioning, migrations, and at least one compatibility test.

Current goal:
Make the material workflow fast and pleasant enough for repeated real use.

Requirements:
- Expand the material browser with:
  - categories
  - tags
  - search
  - favorites
  - recent materials
- Preserve compatibility with existing face assignment workflow.
- Keep the implementation performant for a modestly larger material set.
- Add small UI refinements necessary to make assignment fast.

Important:
- This is a workflow slice, not a rendering-tech slice.
- Prefer fast browsing and assignment over over-designed visuals.
- Do not introduce a complicated backend or remote library system yet.

Testing expectations:
- Domain tests for favorites/recent logic if introduced
- Browser tests for search/filter behavior if practical
- Manual QA for speed of assignment flow

Please implement fully and report:
- material browser improvements
- data model changes
- performance considerations
- how to verify the workflow manually
```

---

## Prompt 17 — Prefab foundation

```text
You are implementing a constrained prefab foundation slice.

Read and follow:
- AGENTS.md
- architecture.md
- roadmap.md
- testing.md

Before coding:
- Inspect the current repo and extend the existing implementation.
- Do not build a dependency-graph editor.
- If you change persisted schema, update versioning, migrations, and at least one compatibility test.

Current goal:
Make repeated reusable scene elements possible with explicit, simple semantics.

Requirements:
- Add a prefab definition concept.
- Allow creating or registering reusable placeable prefab content.
- Allow placing prefab instances in the scene.
- Persist prefab definitions and instances through save/load.
- Add a prefab browser or equivalent UI affordance.

Use these v1 semantics unless the repo already has a clearly compatible equivalent:
- prefab instances reference a prefab definition by ID
- instance transform is allowed
- no per-instance internal structural overrides yet
- definition changes do not silently live-update all instances; provide an explicit refresh/apply path if updates are supported

Important:
- Keep prefab semantics simple and explicit.
- Do not build a full dependency graph editor.
- Be clear about what is supported vs deferred.

Testing expectations:
- Serialization tests
- Domain tests for prefab instance behavior
- Manual/e2e verification for placing multiple instances

Please implement fully and report:
- prefab data model
- instance/update behavior
- UI workflow
- limitations and deferred features
```

---

## Prompt 18 — GLB export improvements

```text
You are implementing the first dedicated export slice.

Read and follow:
- AGENTS.md
- architecture.md
- roadmap.md
- testing.md

Before coding:
- Inspect the current repo and extend the existing implementation.
- Keep canonical JSON as the authoring format.
- If you change persisted schema, update versioning, migrations, and at least one compatibility test.

Current goal:
Improve GLB/GLTF export from the authored scene without distorting the editor data model.

Requirements:
- Improve or add GLB/GLTF export from the authored scene.
- Build export data downstream from the canonical document and/or runtime build.
- Preserve material, asset, animation, and scene structure as sensibly as possible.
- Add minimal export-oriented validation or diagnostics if needed.
- Do not conflate export with the canonical save format.
- Do not build a standalone packaged runner in this slice.

Important:
- Export is downstream from the authoring document/runtime build.
- Do not distort the editor data model to match export constraints.

Testing expectations:
- Export tests with small fixtures
- Manual verification that exported output loads in the runner or a standard viewer if applicable

Please implement fully and report:
- export flow
- what is included vs omitted in export
- what limitations remain
- how to verify the exported result
```

---

## Prompt 19 — Scene packaging and embeddable runner

```text
You are implementing the packaging/deployment slice.

Read and follow:
- AGENTS.md
- architecture.md
- roadmap.md
- testing.md

Before coding:
- Inspect the current repo and extend the existing implementation.
- Keep this separate from canonical save/load and separate from plain GLB export.

Current goal:
Make scenes more shareable and deployable through packaged runner output.

Requirements:
- Clarify and implement a scene packaging path.
- Add or improve a standalone/embeddable runner route if appropriate for the current architecture.
- Package the runtime scene and required assets/materials so the result can be opened without the editor.
- Keep the implementation small and explicit.
- Add any minimal production-oriented optimization hooks that are easy and justified.
- Do not redesign the editor just to support packaging.

Important:
- Canonical JSON remains the authoring format.
- Packaging is downstream from authoring and runtime build.
- This slice is about deployment/shareability, not about changing authoring semantics.

Testing expectations:
- Packaging tests with small fixtures if practical
- Manual verification that a packaged scene loads in the standalone/embedded runner

Please implement fully and report:
- packaging flow
- output options
- what is included vs omitted
- how to verify the packaged result
```

---

## Meta prompt — Audit the slice before merging

```text
Please audit the current branch/work for architecture compliance and slice completeness.

Read and use:
- AGENTS.md
- architecture.md
- roadmap.md
- testing.md

Then inspect the implementation and answer these questions by making concrete improvements where needed:

1. Does the slice work end-to-end?
2. Is the canonical document still clearly separated from three.js runtime/editor objects?
3. Are editor mutations routed through commands?
4. Are save/load and undo/redo covered where they should be?
5. If persisted schema changed, were versioning, migrations, and compatibility tests updated?
6. Are there obvious missing tests for the slice?
7. Are there speculative abstractions or dead scaffolds that should be removed?
8. Are failure modes surfaced clearly enough?
9. Does the implementation still match the intended vertical slice, without scope creep?

Please:
- inspect the current repo first
- make targeted improvements
- remove unnecessary scaffolding if present
- add missing tests if obvious
- run the narrowest relevant checks if possible
- report remaining risks honestly
```