# AGENTS.md — Build guide for Excalidraw+

## Project scope
Embed the maintained Excalidraw component, save complete scene/file snapshots and organize boards locally. Add reusable symbols, frames and editable scene export before considering collaboration.

Catalogue verdict: yes. Excalidraw+'s solo core is compact: build a browser-based collaborative whiteboard editor with drag, resize, connect, keyboard shortcuts, autosave, and SVG or PNG export. A competent builder can reach a useful personal version in one sitting, while the paid product mainly wins on interaction polish, collaboration.
Use the implementation prompt below to define the deliverable. Complete each phase's acceptance checks before extending the scope.

## Working agreement
- Inspect the repository and its existing instructions before choosing paths, dependencies or commands. Keep one coherent stack and explain changes to the proposed architecture.
- Plan a vertical slice that accepts a real input and produces the useful output described below. Persist only the state the prompt calls for; respect memory-only and upstream-managed workflows. Use fixtures only when they are clearly labelled.
- After scaffolding, document the actual install, development, check and build commands in README and keep them synchronized with the package or project manifest. Do not report commands as successful unless they ran.
- Work in small steps. At handoff, list implemented flows, checks actually performed, remaining blockers, and any credentials or provider setup the owner must supply.
- Do not publish, spend money, contact customers, delete source data or run irreversible migrations without the project owner's authorization.

## Prerequisites
- A supported Node release for development and a modern browser. Ship a static bundle that can work locally without an account.
- Implementation components: Vite, React and the maintained @excalidraw/excalidraw component with its upstream scene/file format. IndexedDB autosave snapshots and a portable scene-plus-assets export; no multiplayer server in this scope.
- Scope boundary: Multiplayer sync, access sharing and end-to-end encryption require separate protocols and security review.

## Stack and architecture
- Vite, React and the maintained @excalidraw/excalidraw component with its upstream scene/file format.
- IndexedDB autosave snapshots and a portable scene-plus-assets export; no multiplayer server in this scope.
- Domain model: Excalidraw scenes, element IDs, files, board revisions, reusable libraries and presentation frames

## Security and data integrity
- Sanitize imported SVG, reject external scripts and oversized assets, and require user selection before reading local files. Keep document contents out of telemetry.
- Correctness boundary: Use the upstream scene format and licensing requirements; appending Yjs to the UI alone does not create correct collaborative editing or encryption.
- Represent edits as reversible commands, debounce autosave, and persist a complete project snapshot before destructive structural changes.
- Export editable JSON with assets and an SVG or PNG rendering. Reopen the editable export to retain layers, relationships and IDs; image exports alone are not backups.

## Agent implementation rules
- Project rule — data model: Excalidraw scenes, element IDs, files, board revisions, reusable libraries and presentation frames
- Project rule — preserve this invariant: Use the upstream scene format and licensing requirements; appending Yjs to the UI alone does not create correct collaborative editing or encryption.
- Project rule — acceptance evidence: Export a scene with an embedded image, reopen it offline and retain editable elements; autosave failure keeps the previous complete scene.

## Optional agent skills and references
- Optional external skill: [vercel-composition-patterns](https://github.com/vercel-labs/agent-skills/blob/main/skills/composition-patterns/SKILL.md) — Design reusable React components with composition, context and explicit component variants. Review its instructions and compatibility before use; it does not grant deployment, data-access or publication permission.
- Optional external skill: [web-design-guidelines](https://github.com/vercel-labs/agent-skills/blob/main/skills/web-design-guidelines/SKILL.md) — Review web interfaces for accessibility, keyboard focus, forms, navigation and interaction quality. Review its instructions and compatibility before use; it does not grant deployment, data-access or publication permission.

Read the linked SKILL.md and its dependencies before adding a skill. Select only the skills matching this project's runtime and task; their documentation does not supply API access, credentials or approval to perform external actions. Pin the reviewed revision where the tool supports it. Follow the chosen agent's documented project-level installation mechanism.

## Distribution ideas
These are optional planning notes. Obtain the owner's approval before publishing or contacting anyone.
- Demonstrate the actual Excalidraw+-inspired workflow with owned or clearly labeled sample data: Embed the maintained Excalidraw component, save complete scene/file snapshots and organize boards locally. Add reusable symbols, frames and editable scene export before considering collaboration.
- Publish a reproducible walkthrough with this observable result: Export a scene with an embedded image, reopen it offline and retain editable elements; autosave failure keeps the previous complete scene.
- Explain who can operate this scoped tool, its setup and ongoing costs, and these remaining product gaps: Multiplayer sync, access sharing and end-to-end encryption require separate protocols and security review. Avoid guaranteed savings, performance scores or implied endorsement.

## Engineering roadmap
1. Phase 1 — Scope and fixtures. Implement this bounded workflow: Embed the maintained Excalidraw component, save complete scene/file snapshots and organize boards locally. Add reusable symbols, frames and editable scene export before considering collaboration. Record prerequisites, select representative user-owned fixtures and document the unsupported features: Multiplayer sync, access sharing and end-to-end encryption require separate protocols and security review.
2. Phase 2 — Durable model. Model Excalidraw scenes, element IDs, files, board revisions, reusable libraries and presentation frames Add migrations or a versioned document format, explicit validation, stable IDs and a visible import-error report. Preserve this rule: Use the upstream scene format and licensing requirements; appending Yjs to the UI alone does not create correct collaborative editing or encryption.
3. Phase 3 — Complete the first useful path. Implement the workflow's input, review and output interface, with clear controls and explicit empty/error states. Represent edits as reversible commands, debounce autosave, and persist a complete project snapshot before destructive structural changes.
4. Phase 4 — Permissions and integration failure. Sanitize imported SVG, reject external scripts and oversized assets, and require user selection before reading local files. Keep document contents out of telemetry. Request integration credentials and permissions only for the enabled feature; show a disconnected state instead of mock results.
5. Phase 5 — Portable handoff. Export editable JSON with assets and an SVG or PNG rendering. Reopen the editable export to retain layers, relationships and IDs; image exports alone are not backups. Include setup, operating limits, fixture walkthrough and shutdown/restart instructions in the README.
6. Phase 6 — Acceptance scenarios. Export a scene with an embedded image, reopen it offline and retain editable elements; autosave failure keeps the previous complete scene. Repeat the workflow after restart and with a denied permission or unavailable dependency; show recoverable failure rather than a success placeholder.

## Paid-product capabilities outside this build
- large template libraries
- high-fidelity import and export
- presentation and enterprise controls
- multiplayer cursors and comments

## Implementation prompt
WORKING SLICE
Embed the maintained Excalidraw component, save complete scene/file snapshots and organize boards locally. Add reusable symbols, frames and editable scene export before considering collaboration.

Build this scoped Excalidraw+-inspired workflow with a documented data model and visible failure states.

Architecture
- Vite, React and the maintained @excalidraw/excalidraw component with its upstream scene/file format.
- IndexedDB autosave snapshots and a portable scene-plus-assets export; no multiplayer server in this scope.

Prerequisites and limits
A supported Node release for development and a modern browser. Ship a static bundle that can work locally without an account.
Outside this release: Multiplayer sync, access sharing and end-to-end encryption require separate protocols and security review.

Data model and correctness
Excalidraw scenes, element IDs, files, board revisions, reusable libraries and presentation frames
Invariant: Use the upstream scene format and licensing requirements; appending Yjs to the UI alone does not create correct collaborative editing or encryption.
Represent edits as reversible commands, debounce autosave, and persist a complete project snapshot before destructive structural changes.

Security and privacy
Sanitize imported SVG, reject external scripts and oversized assets, and require user selection before reading local files. Keep document contents out of telemetry.

Recovery and export
Export editable JSON with assets and an SVG or PNG rendering. Reopen the editable export to retain layers, relationships and IDs; image exports alone are not backups.

Implementation order
1. Phase 1 — Scope and fixtures. Implement this bounded workflow: Embed the maintained Excalidraw component, save complete scene/file snapshots and organize boards locally. Add reusable symbols, frames and editable scene export before considering collaboration. Record prerequisites, select representative user-owned fixtures and document the unsupported features: Multiplayer sync, access sharing and end-to-end encryption require separate protocols and security review.
2. Phase 2 — Durable model. Model Excalidraw scenes, element IDs, files, board revisions, reusable libraries and presentation frames Add migrations or a versioned document format, explicit validation, stable IDs and a visible import-error report. Preserve this rule: Use the upstream scene format and licensing requirements; appending Yjs to the UI alone does not create correct collaborative editing or encryption.
3. Phase 3 — Complete the first useful path. Implement the workflow's input, review and output interface, with clear controls and explicit empty/error states. Represent edits as reversible commands, debounce autosave, and persist a complete project snapshot before destructive structural changes.
4. Phase 4 — Permissions and integration failure. Sanitize imported SVG, reject external scripts and oversized assets, and require user selection before reading local files. Keep document contents out of telemetry. Request integration credentials and permissions only for the enabled feature; show a disconnected state instead of mock results.
5. Phase 5 — Portable handoff. Export editable JSON with assets and an SVG or PNG rendering. Reopen the editable export to retain layers, relationships and IDs; image exports alone are not backups. Include setup, operating limits, fixture walkthrough and shutdown/restart instructions in the README.
6. Phase 6 — Acceptance scenarios. Export a scene with an embedded image, reopen it offline and retain editable elements; autosave failure keeps the previous complete scene. Repeat the workflow after restart and with a denied permission or unavailable dependency; show recoverable failure rather than a success placeholder.

Acceptance
Export a scene with an embedded image, reopen it offline and retain editable elements; autosave failure keeps the previous complete scene.
Use real source data or clearly labeled fixtures. Explain unsupported input and provider failures; do not fabricate analytics, delivery receipts, accuracy claims or security guarantees.

Optional agent guidance
Optional external skill: [vercel-composition-patterns](https://github.com/vercel-labs/agent-skills/blob/main/skills/composition-patterns/SKILL.md) — Design reusable React components with composition, context and explicit component variants. Review its instructions and compatibility before use; it does not grant deployment, data-access or publication permission.
Optional external skill: [web-design-guidelines](https://github.com/vercel-labs/agent-skills/blob/main/skills/web-design-guidelines/SKILL.md) — Review web interfaces for accessibility, keyboard focus, forms, navigation and interaction quality. Review its instructions and compatibility before use; it does not grant deployment, data-access or publication permission.
Project rule — data model: Excalidraw scenes, element IDs, files, board revisions, reusable libraries and presentation frames
Project rule — preserve this invariant: Use the upstream scene format and licensing requirements; appending Yjs to the UI alone does not create correct collaborative editing or encryption.
Project rule — acceptance evidence: Export a scene with an embedded image, reopen it offline and retain editable elements; autosave failure keeps the previous complete scene.

## Completion evidence
Demonstrate the prompt's acceptance scenarios against the scoped workflow. Include setup from a clean checkout and failure recovery. Check persistence across restart and export/restore only for the state the prompt says to store; for memory-only tools, confirm that temporary content is discarded as specified. Record actual results and remaining limitations. A detailed plan alone does not establish a working replacement.