# AGENTS.md — Build guide for Vimeo ## Project scope Transcode a user-owned video to a small HLS ladder, upload completed assets and serve a player/embed page with explicit public, unlisted or protected visibility. Catalogue verdict: kinda. Hosting your own video stopped being exotic: ffmpeg builds the HLS ladder, object storage holds it, a CDN serves it, and hls.js plays it. For a portfolio or a client reel that is a weekend, and the result has no ads, no upsells, and no platform that can change its mind about your account. What you are actually buying from Vimeo is the delivery layer holding up when 4,000 people open the link at once, plus live streaming, captions, analytics, and a player that has been QA'd against every browser, smart TV, and embed context you will never test. Small library, predictable traffic · build it. Anything with a spike in it · the bandwidth bill is the whole argument. 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 - Do not publish, spend money, contact customers, delete source data or run irreversible migrations without the project owner's authorization.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, better-sqlite3, FFmpeg, hls.js and a configured private object-storage/CDN delivery path. - Before starting: A licensed source video, FFmpeg, a storage account and delivery policy that protects manifests and every referenced media segment. ## Stack and architecture - Node, Express, better-sqlite3, FFmpeg, hls.js and a configured private object-storage/CDN delivery path - Data design: Store Video, Rendition, UploadManifest, Visibility and AccessGrant; publish only a complete ladder and enforce protected access on playlists, segments and poster files. - Setup: A licensed source video, FFmpeg, a storage account and delivery policy that protects manifests and every referenced media segment ## 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. - Unlisted is not private. Do not gate only the HTML page while leaving media public; retention, CDN cache behavior and bandwidth charges belong in setup. Live streaming and monetization are deferred. - 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 Video, Rendition, UploadManifest, Visibility and AccessGrant; publish only a complete ladder and enforce protected access on playlists, segments and poster files. - Project rule — scope and recovery: Unlisted is not private. Do not gate only the HTML page while leaving media public; retention, CDN cache behavior and bandwidth charges belong in setup. Live streaming and monetization are deferred. - Project rule — acceptance: Upload fails halfway and a protected playlist URL is copied; keep the old publication intact and prevent direct unauthorized segment retrieval. - 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: Transcode a user-owned video to a small HLS ladder, upload completed assets and serve a player/embed page with explicit public, unlisted or protected visibility. - Share a synthetic example export and the acceptance walkthrough; keep real customer, health, financial and source data private: Upload fails halfway and a protected playlist URL is copied; keep the old publication intact and prevent direct unauthorized segment retrieval. - State the limits before asking someone to replace their existing tool: Unlisted is not private. Do not gate only the HTML page while leaving media public; retention, CDN cache behavior and bandwidth charges belong in setup. Live streaming and monetization are deferred. ## Engineering roadmap 1. Phase 1 — Pin the working slice and create its example input: Transcode a user-owned video to a small HLS ladder, upload completed assets and serve a player/embed page with explicit public, unlisted or protected visibility. Confirm setup: A licensed source video, FFmpeg, a storage account and delivery policy that protects manifests and every referenced media segment. 2. Phase 2 — Implement persistence and write-time invariants before decorating the UI: Store Video, Rendition, UploadManifest, Visibility and AccessGrant; publish only a complete ladder and enforce protected access on playlists, segments and poster files. 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: Unlisted is not private. Do not gate only the HTML page while leaving media public; retention, CDN cache behavior and bandwidth charges belong in setup. Live streaming and monetization are deferred. 5. Phase 5 — Walk through this concrete acceptance case and preserve its exported evidence: Upload fails halfway and a protected playlist URL is copied; keep the old publication intact and prevent direct unauthorized segment retrieval. Finish the README and backup/restore instructions; report unfinished capabilities explicitly. ## Paid-product capabilities outside this build - live streaming, webinars, and events - auto captions, chapters, and the accessibility tooling around them - viewer analytics and engagement graphs - OTT, pay-per-view, and the monetization stack - a player QA'd against every browser, smart TV, and embed surface - traffic spikes absorbed by someone else's bandwidth bill ## Implementation prompt Build the following focused alternative to Vimeo. This is a deliberately limited personal or small-team substitute, not parity with the paid service. WORKING SLICE Transcode a user-owned video to a small HLS ladder, upload completed assets and serve a player/embed page with explicit public, unlisted or protected visibility. SETUP AND ARCHITECTURE Use Node, Express, better-sqlite3, FFmpeg, hls.js and a configured private object-storage/CDN delivery path. Prerequisites: A licensed source video, FFmpeg, a storage account and delivery policy that protects manifests and every referenced media segment. 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 Video, Rendition, UploadManifest, Visibility and AccessGrant; publish only a complete ladder and enforce protected access on playlists, segments and poster files. 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 Unlisted is not private. Do not gate only the HTML page while leaving media public; retention, CDN cache behavior and bandwidth charges belong in setup. Live streaming and monetization are deferred. ACCEPTANCE SCENARIO Upload fails halfway and a protected playlist URL is copied; keep the old publication intact and prevent direct unauthorized segment retrieval. 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.