# AGENTS.md — Build guide for Tella ## Project scope Record a selected screen and optional webcam in the browser, trim the result, review an MP4 render and deliberately publish a share page. Catalogue verdict: yes. For solo async clips, a recorder plus lightweight trimming and hosted share page can be vibecoded; the paid app wins on design polish and templates. 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 - Do not publish, spend money, contact customers, delete source data or run irreversible migrations without the project owner's authorization.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 - Runtime and tools: Node, Express, browser MediaRecorder/getDisplayMedia/getUserMedia, FFmpeg and SQLite share metadata. - Before starting: A supported browser on localhost/HTTPS, microphone/screen permissions, FFmpeg and an optional authenticated upload target. ## Stack and architecture - Node, Express, browser MediaRecorder/getDisplayMedia/getUserMedia, FFmpeg and SQLite share metadata - Data design: Store Recording, ScreenTrack, WebcamTrack, TrimRange and UploadReceipt; track synchronization is explicit and publishing references an approved completed render. - Setup: A supported browser on localhost/HTTPS, microphone/screen permissions, FFmpeg and an optional authenticated upload target ## Security and data integrity - Keep source files immutable and store edit decisions separately. Run media tools with argument arrays, bounded file size/runtime and unique job directories; only rename a completed export into its final location. - Browser capture requires user permission and supported audio sources. Keep local originals, authenticate uploads and clarify public/unlisted sharing; 'unlisted' is not private access control. - Keep secrets outside client bundles and exported projects; document what leaves the device and make retention/deletion controls visible. ## Agent implementation rules - Project rule — domain: Store Recording, ScreenTrack, WebcamTrack, TrimRange and UploadReceipt; track synchronization is explicit and publishing references an approved completed render. - Project rule — scope and recovery: Browser capture requires user permission and supported audio sources. Keep local originals, authenticate uploads and clarify public/unlisted sharing; 'unlisted' is not private access control. - Project rule — acceptance: Deny webcam access but allow the screen, stop sharing from browser chrome and render; offer screen-only recording and finalize a recoverable file instead of losing the session. - Project rule — delivery: document real setup commands and permissions; do not claim a build, accuracy level, performance result or security certification that has not been demonstrated. ## Optional agent skills and references - Recommended skill: [web-design-guidelines](https://github.com/vercel-labs/agent-skills/blob/main/skills/web-design-guidelines/SKILL.md) — review keyboard access, focus, validation, error recovery and the readable work/review interface or HTML report. Follow the maintainer's installation instructions and match its requirements to the chosen runtime. - Recommended skill: [sharp-edges](https://github.com/trailofbits/skills/blob/main/plugins/sharp-edges/skills/sharp-edges/SKILL.md) — review configuration and API defaults against the app-specific invariants and recovery boundaries above; this is not a security certification. Follow the maintainer's installation instructions and match its requirements to the chosen runtime. 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 this working slice using synthetic or explicitly authorized non-sensitive examples: Record a selected screen and optional webcam in the browser, trim the result, review an MP4 render and deliberately publish a share page. - Share a synthetic example export and the acceptance walkthrough; keep real customer, health, financial and source data private: Deny webcam access but allow the screen, stop sharing from browser chrome and render; offer screen-only recording and finalize a recoverable file instead of losing the session. - State the limits before asking someone to replace their existing tool: Browser capture requires user permission and supported audio sources. Keep local originals, authenticate uploads and clarify public/unlisted sharing; 'unlisted' is not private access control. ## Engineering roadmap 1. Phase 1 — Pin the working slice and create its example input: Record a selected screen and optional webcam in the browser, trim the result, review an MP4 render and deliberately publish a share page. Confirm setup: A supported browser on localhost/HTTPS, microphone/screen permissions, FFmpeg and an optional authenticated upload target. 2. Phase 2 — Implement persistence and write-time invariants before decorating the UI: Store Recording, ScreenTrack, WebcamTrack, TrimRange and UploadReceipt; track synchronization is explicit and publishing references an approved completed render. 3. Phase 3 — Connect the working view to real saved state. Keep source files immutable and store edit decisions separately. Run media tools with argument arrays, bounded file size/runtime and unique job directories; only rename a completed export into its final location. 4. Phase 4 — Expose the app-specific limits and recovery path in context: Browser capture requires user permission and supported audio sources. Keep local originals, authenticate uploads and clarify public/unlisted sharing; 'unlisted' is not private access control. 5. Phase 5 — Walk through this concrete acceptance case and preserve its exported evidence: Deny webcam access but allow the screen, stop sharing from browser chrome and render; offer screen-only recording and finalize a recoverable file instead of losing the session. Finish the README and backup/restore instructions; report unfinished capabilities explicitly. ## Paid-product capabilities outside this build - beautiful layouts - browser extension/native polish - templates - team sharing - reliable video hosting ## Implementation prompt Build the following focused alternative to Tella. Implement the focused workflow below first; the verdict is not evidence of a completed or production-certified build. WORKING SLICE Record a selected screen and optional webcam in the browser, trim the result, review an MP4 render and deliberately publish a share page. SETUP AND ARCHITECTURE Use Node, Express, browser MediaRecorder/getDisplayMedia/getUserMedia, FFmpeg and SQLite share metadata. Prerequisites: A supported browser on localhost/HTTPS, microphone/screen permissions, FFmpeg and an optional authenticated upload target. Before integrating anything, record actual versions and permissions, plus model files or provider limits only where used, in the README; make unavailable dependencies visible rather than simulating success. DOMAIN MODEL AND INVARIANTS Store Recording, ScreenTrack, WebcamTrack, TrimRange and UploadReceipt; track synchronization is explicit and publishing references an approved completed render. IMPLEMENTATION CONTRACT Keep source files immutable and store edit decisions separately. Run media tools with argument arrays, bounded file size/runtime and unique job directories; only rename a completed export into its final location. Provide an input/setup view, the main work view, and a review/export view appropriate to this workflow. Preserve the last saved state if a job or save fails. Include empty, loading, permission-denied, partial and retryable-error states. Log identifiers and error categories without secret values or unnecessary private content. APP-SPECIFIC BOUNDARY AND RECOVERY Browser capture requires user permission and supported audio sources. Keep local originals, authenticate uploads and clarify public/unlisted sharing; 'unlisted' is not private access control. ACCEPTANCE SCENARIO Deny webcam access but allow the screen, stop sharing from browser chrome and render; offer screen-only recording and finalize a recoverable file instead of losing the session. Also reopen the app after an interrupted operation, confirm the saved record/export remains inspectable, and document the recovery action. These are implementation acceptance requirements, not a claim that this guide has been tested. DELIVERY Deliver a runnable repository with migrations or project-format versioning, a non-sensitive example, environment/permission setup, the exact manual acceptance steps, and a backup/export-and-restore walkthrough. Implement the working slice before optional integrations; list any deferred paid-product capabilities honestly. Do not add capabilities outside the working slice just to resemble the original product. PROJECT RULES FOR AGENTS.md Keep the domain invariants above executable at the write boundary. Propose scope changes before adding providers or permissions. Never fabricate source evidence, publish results, identity matches or successful delivery. Preserve user originals and require an explicit confirmation for destructive changes or external publication. ## 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.